international rice research notes vol.18 no.3

International Rice Research Notes

The International Rice Research Notes (IRRN) expedites communication among scientists concerned with the development of improved technology for rice and rice- based systems.

to help scientists keep each other informed of current rice research findings. The concise scientific notes are meant to encourage rice scientists to communicate with one another to obtain details on the research reported.

The IRRN is published quarterly in March, June, September, and December by the International Rice Research Institute; annual subject and variety indexes are also produced.

The IRRN is divided into three sections: notes, news about research collaboration, and announcements.

The IRRN is a mechanism

ISSN 0115-0944

Contents September 1993

Germplasm improvement

Genetics 4 Improved lines with wide compatibility (WC)

gene of Moroberekan

Breeding methods 4 A self-sustaining system for hybrid rice seed

5 Two-line hybrid rice in China 5 Heterosis and combining ability evaluation of

cytoplasmic male sterile (A) lines and restorer (R) lines

6 Isolation-free system for producing experimental hybrid rice seed for preliminary evaluation

7 Identifying maintainer and restorer lines for hybrid rice in Himachal Pradesh (HP), India

8 Maintainers and restorers for four cytoplasmic male sterile (CMS) lines

8 Identifying maintainers and restorers of cytoplasmic genetic male sterile (CMS) lines for hybrid rice breeding

9 Genotypic differences in embryogenic callus formation and plant regeneration in indica rice

10 Effect of interaction between genotype and culture medium on callus induction and plant regeneration of anther culture of Vietnamese indica rice ( Oryza sativa L.)

production

Yield potential 11 Different grades of grain occur during grain

filling in short- and medium-duration rice

Pest resistance—diseases 12 Using pedigree analysis to identify sources of

resistance to rice hoja blanca virus (RHBV) 3 Detection of rice tungro bacilliform virus

(RTBV) in asymptomatic leaves of tungro- infected rice plants by polymerase chain reaction (PCR)

rot disease

production technology

resistant varieties developed at Maruteru, Andhra Pradesh (AP), India

14 Evaluation of resistance to bakanae and foot

15 Pathological constraints on hybrid rice

15 High-yielding, brown planthopper (BPH)-

Pest resistance—other pests 16 Susceptibility of wild rice species to nematode

Meloidogyne graminicola

Stress tolerance—adverse soils 17 Comparative studies of germination and

seedling growth of some salt-tolerant selections at different salinity levels

lntegrated germplasm improvement—irrigated 18 ADT41 (JJ92), a short-duration Basmati rice for

18 Mahsuri derivatives developed: Kushal,

19 On-farm evaluation of rice cultivars for spring

20 IR36-derived lines are stable high yielders in

20 Wei You 647: a new high-yielding hybrid rice 21 KSB54, a new variety with moderate resist-

ance to Mekong Delta population of brown planthopper (BPH) ( Nilaparvata lugens Stål)

high yield, blast (BI) resistance, and good quality

Tamil Nadu, India

Maniram, Bahadur, and Ranjit

season in the lower hills of Chitwan, Nepal

Kerala, India

21 Zhenong 8010: a new indica rice variety with

lntegrated germplasm improvement— rainfed lowland 22 Bogabordhan: a stable, high-yielding, low-input

traditional variety of Assam, India

lntegrated germplasm improvement—upland 22 Upland rice varieties Sita and Rimke released

23 Vandana (RR167-982), a new upland variety in to farmers in Cambodia

the plateau region of Bihar, India

lntegrated germplasm improvement—deepwater 24 Performance of some promising deepwater

rice (DWR) cultivars in northwestern Nigeria

lntegrated germplasm improvement—tidal wetlands 25 Netravathi (KKP-6): a promising rice variety for

coastal lowlands of Karnataka, India

Crop and resource management

Physiology and plant nutrition 26 Nitrate reductase (NRase) activity as an index

for early maturity

Fertilizer management 27 Comparative efficiency of Sesbania, Gliricidia,

and urea as N sources in wetland rice

Fertilizer management—inorganic sources 27 Effect of lignite fly ash (LFA) on rice

Fertilizer management—organic sources 28 Using desiccation to preserve blue-green algae

28 Effects of Sesbania aculeata (dhaincha) on rice (BGA)

yield

Crop management 29 Comparative yields and N uptake in six

transplanted and direct seeded lowland rices

lntegrated pest management—diseases 30 Occurrence of rice grain rot disease in Vietnam 30 Treating rice seeds with fungicides and

31 Effect of foliar spraying of Aspergillus terreus antagonists to control seedborne diseases

Thom on sheath blight (ShB) and rice plant characteristics

(ShR) of rice

(Xoo) among strains representing major rice- growing areas of India and Nepal

lntegrated pest management-insects 34 Effects of neem and nochi on rice bug

Leptocorisa acuta 34 Developmental biology and host plant range of

rice-feeding tiger moth Creatonotus gangis (L.) 35 Shifts in population characteristics of brown

planthopper (BPH) immigrants to Japan 37 Detoxifying enzymes of the brown planthopper

(BPH)

33 Efficacy of botanicals in managing sheath rot

33 New races of Xanthomonas oryzae pv. oryzae

lntegrated pest management—other pests 37 Efficacy of benomyl in controlling the ufra

nematode in Vietnam

Water management 38 Water management in transplanted wetland

rice

farming systems 39 Establishing rainfed no-till winter crops under

39 Varietal diffusion in a rice farming system 40 Rice -fish - azolla farming system for low-lying

NPK fertilization after transplanted wet rice

ricefields

Research methodology 41 Combined effects of pests in farmers' fields:

methodological outlines of a yield-loss data base in rice

42 A simple methodology for analyzing rice sheath blight (ShB) epidemiologic processes under semicontrolled conditions

43 Maximum diseased leaf area (DLA): a new parameter for leaf blast (BI) severity

News about research collaboration

44 IRRI-CIMMYT on Rice-Wheat

44 Vietnamese rice farmers quickly adopt

44 German Government and Asian Development

Collaboration

"water seeding"

Bank help IRRI launch Asian Rice Biotechnology Network

Announcements

45 Rice dateline 45 Postdoctoral research fellowship positions at

IRRI 46 Climate Change and Rice Symposium 46 Who are the outstanding young women

46 IRRI 1993 group training courses 46 Rice literature update reprint service 47 UNE 1994 short courses 47 Wet seeded rice workshop 47 Temperate rice conference 47 Revised Journal of production

in rice science?

agriculture Introduced by ASA, CSSA, and SSSA

47 Call for news 48 Rice conference for Latin America

48 New publicatlon 48 IRRI address

Instructions for contributors

Inside back cover

and the Caribbean

cpsadmin

Text Box

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Germplasm improvement

Improved lines with wide compatibility (WC) gene of Moroberekan D. Senadhira, R. M. Herrera, and J. P. Roxas, IRRI

We previously reported that the WC gene of Moroberekan is very effective but that this upland variety might not be the best WC source for use in lowland rice breeding programs. Moroberekan

and plant type characteristics. Pedigree selection was used thereafter. In the F 7 generation, agronomically uniform lines from two crosses were tested for the presence of the WC gene. The lines were hybridized with an indica (IR36) and a japonica (Akihikari); F 1 fertility was examined.

All lines of the cross IR61 315 (Moroberekan/IR66) showed normal fertility (>85%) with IR36 but were partially fertile (<40%) with Akihikari. Five lines derived from the cross

IR61614 (IR32429-47-3-2-2*2/ Moroberekan) showed normal fertility with both japonica and indica testers. They were tested again in 1993 dry season (DS) and the presence of the WC gene in IR61614 lines was confirmed (see table).

are adapted to anaerobic soil conditions and possess high-yielding plant type characteristics. They mature in 125 d and are highly resistant to blast. Seeds of these lines are available from IRRI.

Unlike Moroberekan, the new lines

performs poorly in anaerobic soil. Uneven tillering and flowering and abnormal tillers are common. Desirable recombinants are rare when Moroberekan is used as a bridge variety in indica × many rice-growing areas. We propose japonica crosses. hybrid rice seed production a system in which hybrid rice growers

Moroberekan to develop improved lines

isolated from adjoining ricefields

A self-sustaining system for condition is difficult to achieve in flowering at the same time. This

We made a series of crosses with S. S. Virmani, J. Manalo, and R. Toledo, IRRI

adapted to flooded soil conditions and possessing Moroberekan’s WC gene. Crosses were advanced under irrigated conditions at IRRI. We used modified bulk method for five generations; selection was based on normal growth

Spikelet fertility of new WC lines, their parents, and F 1 with japonica (Akihikari) and indica (IR36) testers. IRRI, 1993 DS.

Spikelet Variety/cross fertility

(%)

IR61614-3B-3-1-1 lR61614-3B-6-2-3 94.4 lR61614-3B-7-3-3 96.6 lR61614-3B-12-3-3 93.9 lR61614-3B-19-3-2 92.2

92.3

I R36 95.2

Akihikari 95.4 Moroberekan 95.9 Akihikari/IR61614-3B-3-1-1 (F 1 ) 87.2 Akihikari/lR61614-3B-6-2-3 (F 1 ) 81.1 Akihikari/lR61614-3B-7-3-3 (F 1 ) 85.4 Akihikari/lR61614-3B-12-3-3 (F 1 ) 87.7 Akihikari/lR61614-3B-19-3-2 (F 1 ) 84.1

lR32429-47-3-2-2 94.9

IR36/IR61614-3B-3-1-1 (F 1 ) 89.5 IR36/IR61614-3B-6-2-3 (F 1 ) 84.6 IR36/IR61614-3B-7-3-3 (F 1 ) 91.5 IR36/IR61614-3B-12-3-3 (F 1 ) 94.7 IR36/IR61614-3B-19-3-2 (F 1 ) 90.8

4 IRRN 18:3 (September 1993)

One of the disadvantages of hybrid rice technology is that cultivators must secure new seeds every season. To produce pure hybrid rice seed, fields must be

Proposed field layout of a self-sustaining system for hybrid rice seed production.

Breeding methods

Genetics

can produce their own hybrid seed using 8-10 d time isolation and no distance isolation.

system, about 5% of the area of a rice farm is used for producing the next season's hybrid rice seed; the rest is used for growing grain. The seed production plot is planted so that it flowers 8-10 d after the main crop flowers to reduce contamination from pollen of commercial hybrids or inbred varieties. Locating the plot in the corner of the farm lessens the chance of contamination from the neighboring farm.

The R (restorer) line is planted in a 3-m-wide strip around the seed production plot, covering about half of it. The actual F 1 seed production plot is

In the self-sustaining seed production

planted with A (maintainer):R lines in a 10-3 row ratio (see figure). The R line strip provides sufficient pollen load to minimize contamination from other pollen sources. Recommended seed production practices, including flag leaf clipping, GA 3 application, and supplementary pollination, are followed to achieve high outcrossing of the A line and thus a high seed yield of A x R hybrid.

Seeds produced at IRRI using this system gave uniform hybrid crops during 1992 dry and wet seasons comparable with ones raised from seeds produced in isolated seed production plots. Seed yield in the A x R area was 50-70 g/m 2 for the hybrid and 100-150 g/m 2 for the R line. Yield from the R line border rows was about 5 t/ha.

Half of a 500-m 2 hybrid rice seed production plot is allocated to plant A and R lines and half to pure R line. This plot will yield 12.5-17.5 kg hybrid seed (enough to plant 1 ha), and about 125 kg R line seed, which can be used as grain. As management improves, hybrid seed yields can be increased to 100-125 g/m 2 ; thus the 500-m 2 hybrid seed production plot can be reduced to 350-400 m 2 . Farmers need to buy only 400 g of A line seed in this system. Although they can use their own R line seed, we advise them to buy 1 kg fresh R line seed every season to ensure seed purity. Public or private sector seed companies can produce foundation seed for A and R lines.

Table 1. PGMS and TGMS lines developed in China.

Mao Chang-Xiang and Deng Xian-Lin, Line Type Province in which developed Hunan Hybrid Rice Research Center, 410125 Changsha, Hunan, China

Chinese scientists have been working to develop two-line hybrid rice to increase K14 S yield and simplify the seed production

7001 S 5088 S 5047 S K9 S

Table 2. Promising two-line hybrid rice being tested.

Province Hybrid Type in which

developed

K9 S/03 Indica Guang Xi Pei Ai 64 S/ Indica Hunan

Pei Ai 64 S/ Indica Hunan

W6154 S/ Indica Hunan

W6154 S/312 Indica Hunan

An Nong S-1/312 Indica Hunan Heng Nong S-1/ Indica Hunan

N8 S/Xiang 26 Indica Hunan 545 S/402 Indica Hunan W6111 S/ Indica Hubei

Xiang Zao Xian 1

Te Qing 2

Te Qing 2

Ming Hui 63

Te Quing 2

5088 S/1514 Japonica Hubei 5088 S/R9-1 Japonica Hubei 5460 S/R9-1 Indica Fujian W6154 S/ Indica Fujian

7001 S/ Japonica An Hui Vary Lava 1312

Lun Hui 422

5460 S 8902 S W6111 S

Pei Ai 64 S

Japonica PGMS Japonica PGMS Japonica PGMS Indica TGMS Indica TGMS

Indica TGMS Indica TGMS Indica TGMS Indica TGMS Indica TGMS

An Nong S-1 Indica TGMS 545 S Indica TGMS N8 S Indica TGMS Heng Nong S-1 Indica TGMS

process. Some photoperiod-sensitive genic male sterile (PGMS) lines, thermo- sensitive genic male sterile (TGMS) lines, and two-line hybrids have been successfully developed (Tables 1 and 2). Japonica mutant Nong Ken 58 S and indica mutants An Nong S- 1 and Heng Nong S-1 are the major sources of these PGMS and TGMS lines.

Some of the promising two-line hybrids have been tested in on-farm and demonstration trials. They were cultivated on 100,000 ha in China during 1991-93. About 2 million ha are expected to be planted to the two-line hybrids by 1995.

An Hui Hubei Hubei Guang Xi Guang Xi

Fujian Hubei Hubei Hubei Hunan

Hunan Hunan Hunan Hunan

Heterosis and combining ability evaluation of cytoplasmic male sterile (A) lines and restorer (R) lines O. Watanesk, Chainat Rice Experiment Station, Chainat, Thailand

The general combining ability (GCA) of four A lines and five R lines and the specific combining ability (SCA), heterosis, heterobeltiosis, and standard heterosis of 20 F 1 hybrids were studied in a line x tester mating design. The 31 treatments of 20 F 1 s, 4 lines, 5 testers, and 2 traditional varieties (RD23 and

IRRN 18:3 (September 1993) 5

Two-line hybrid rice in China

Table 1. General combining ability effects a of parents for grain yield and other characters. Chainat, Thailand, 1992 WS.

Grain Days to 50% Plant Tillers/ 100-grain Spikelets/ % unfilled Panicle Parent yield flowering height hill wt panicle grain length

A lines CNTA-1 14.43 2.40** 1.26* 0.34 –0.02* CNTA-7

4.60 3.82

2.52* 0.50*

0.02 0.99 –0.19 –0.03** 10.71**

CNTA-10 16.28 1.85** 9.65** 0.66 0.22 1.44

3.51** –0.03

–0.16 –0.01 CNTA-34

SE –34.53* –4.82** –5.76** 0.01 0.06** –24.95** –4.62** –0.2

13.89 0.25 0.72 0.31 0.01 2.54 1.00 0.14 R lines CNTLR80140-14-1-1-1 28.03 1.32** –8.74** 1.04** 0.02** –10.60** RD7 –127.49**

–1.02 –1.47** 1.74** 1.95* –1.35** 0.05** –5.15 7.65** 0.45**

C4-63 –37.93* –1.76** –4.97** –0.08 –0.10** 7.65** 5.61** –0.85** SPRLR77034-PSL-17-1-1-1 52.53** –0.43 3.13** –0.45 0.03** 4.65 –7.44** 0.78** SPRLR75055-352-2-1 89.84** –0.87** 8.63** 0.85* 0.01 3.46 –4.79** 1.09**

SE 15.53 0.28 0.81 0.34 0.01 2.84 1.12 0.15 a *, ** = significant at the 5 and 1% levels, respectively.

Table 2. Heterosis (Ht), heterobeltiosis (Hb), and standard heterosis (Sh) in yield of the top 5 F 1 hybrids at Chainat, Thailand, 1991 WS.

F 1 hybrid Grain yield (%)

Grain yield a

(g/1.19 m 2 ) Ht Hb Sh

over RD23 over SPR60

CNTA-10/CNTLR80140-14-1-1-1 570.5 abcde 44.5 23.7 32.4 28.4 CNTA-10/SPRLR77034-PSL-17-1-1-1 654.0 a 43.9 41.8 51.7 47.2 CNTA-1/CNTLR80140-14-1-1-1 577.3 abcd 43.8 21.0 33.9 29.9 CNTA-7/SPRLR75055-352-2-1 641.8 ab 42.5 34.6 48.9 44.4 CNTA-34/CNTLR80140-14-1-1-1 517.3 cdefg 41.6 28.6 20.0 16.4

CNTA-1 CNTA-7 CNTA-10 CNTA-34

477 defghi 476.8 defghi 461.3 fghijk 402.3 hijkl

CNTLR80140-14-1-1-1 328.3 I RD7 371.8 jkl C4-63 366.5 jkl SPRLR77034-PSL-17-1-1-1 447.8 fghijk SPRLR75055-352-2-1 423.8 ghijkl

RD23 SPR60

CV = 12.4 %

431.0 ghijk 444.3 fghijk

a ln a column, means followed by a common letter are not significantly different at the 5% level by DMRT.

SPR60) were laid out in a randomized for yield, plant height, and panicle length complete block design with four (Table 1). CNTA-1 had the best GCA replications in 1992 wet season (WS). Each treatment (plot) was one row of

effect for tillers/hill, CNTA-7 for

good general combiners for yield, plant 1.19 m 2 for yield analysis. and SPRLR77034-PSL-17-1-1-1 were component analysis and 19 plants from

For the R lines, SPRLR75055-352-2-1 plot were randomly measured for yield and low % unfilled grain. 25-cm spacing. Five plants from each days to 50% flowering, 100-grain weight, 21 plants, one plant per hill, with 25- × spikelets/panicle, and CNTA-34 for early

CNTA-1 were good general combiners length (Table 1). For the A lines, CNTA- 10 and height, low % unfilled grain, and panicle

C4-63 had the best GCA effect for early days to 50% flowering and spikelets/panicle, RD7 for 100-grain weight, and CNTLR80140-14-1-1-1 for tillers/hill.

CNTLR80140-14-1-1-1 had the highest heterosis in yield at 44.5% (Table 2).

had the highest heterobeltiosis at 41.8% and standard heterosis at 5 1.7% more than RD23 and 47.2% more than

The F 1 cross of CNTA- 10/

CNTA-10/SPRLR77034-PSL-l7-1-1-1

SPR60.

Isolation-free system for producing experimental hybrid rice seed for preliminary evaluation S. S. Virmani and C. Casal, IRRI

Artificial hybridization is impractical when hundreds of hybrid combinations requiring thousands of seeds must be produced for yield testing each season. We developed an isolation-free system for producing experimental hybrid rice seed for evaluation in preliminary yield trials.

In the system, various restorer (R) lines are grown side-by-side in 5- × 3-m plots (see figure). On the four sides of each plot, four rows of R plants are planted at 20- × 20-cm spacing to form a border to provide some isolation from adjoining plots. In the center of each plot are four 40-cm-wide vacant spaces, interspersed by single rows of R plants. The spaces can accommodate


up to 68 cytoplasmic male sterile (CMS) (A) plants at flowering (see figure).

A lines of experimental hybrids are planted five times at an 8-10 d interval.

Layout for isolation- free system for producing experimental rice hybrid seed.

This staggered planting ensures a continuous supply of flowering A plants to synchronize with the flowering of R movement to the adjoining plots is lines in different seed production plots. minimized by disturbing only R plants A lines are planted upwind from R lines immediately surrounding the A plants. and near the seed production plots to Supplementary pollination is done for facilitate the transport of plants. 5-7 d or until pollen of a R line is

When primary tillers of A and R lines exhausted. R line plants from seed are at booting, their flag leaves are production plots are harvested first, clipped. The two outermost border rows followed by A plants bearing the (A × R) in the R plots are not clipped to demar- F 1 seeds. cate the plots and to act as a barrier to Two CMS lines yielded 4-5 g hybrid pollen from adjoining plots. Three to five seed/plant during wet season and d after clipping, A plants are uprooted 7-10 g seed/plant during dry season using and relocated to the vacant spaces. this system. Five to ten plants of a CMS Uprooting is done between 0630 h and line can produce 40 g of experimental 0800 h to reduce shock. A line plants are hybrid seed for evaluation in an observa- not used if more than 20% of their tion yield trial for two seasons. Twenty to spikelets have already bloomed. 40 plants can produce 150 g experimen-

anthesis (1030 h to 1 100 h) by shaking R replicated preliminary yield trial for two line panicles with a bamboo stick. Pollen seasons.

Pollen dispersal is increased at peak tal hybrid seed for evaluation in a

We have been using the isolation-free seed production system at IRRI for the past three seasons. During 1992, we produced seeds of 103 experimental hybrids for evaluation in preliminary yield trials. Seed contamination was 0-8%, with a mean of 1.7%.

We strongly recommend that hybrid rice breeders in national programs use this system for producing experimental hybrid rice seed for evaluation in preliminary yield trials.

Identifying maintainer and restorer lines for hybrid rice in Himachal Pradesh (HP), India G. S. Oinam and R. P. Kaushik, Plant Breeding and Genetics Department, Himachal Pradesh Krishi Vishvavidalaya (HPKV), Palampur 176062, HP, India

Identifying maintainer and restorer lines in traditional varieties (TVs) and modern varieties (MVs) adapted to the agroclimatic conditions of HP is a prerequisite to initiating a hybrid rice program in the state. Cytoplasmic male sterile (CMS) line V20 A, which pos- sesses wild abortive (WA) cytoplasm, seems ideally suited for this purpose.

Identified maintainer and restorer lines a of V20 A at HPKV, Palampur, HP, India, 1991 wet season.

Based on Cultivar

Pollen Spikelet fertility fertility

Himdhan M M R575 M M Kaladhan M M CH1039 M M

HPU2202 M M Debal M M HPU5101 M M CH988 M M K39 PR PR Himalaya 741 – PR HPU799 – PR HPU2216 – PR

IR18482-Plp3-2-5-2 M M

lR9129-263-3-3-3-2-3-2 – PR HPU5039-PIp13-4-4-6-3B PR PR

a M = effective maintainer (0% fertility), PR = partial restorer (10-69% pollen fertility and 10–79% spikelet fertility).


A set of 16 locally used TVs and MVs

restorers have spikelet fertility of 80% from bagged hybrid plants. used to identify restorers. Effective Estimates were based on five panicles fertility. Therefore, spikelet fertility was were screened for sterile/fertile pollen. correlation ( r = 0.24) with spikelet squashed in 1% iodine solution. Slides

Pollen fertility did not show any placed together on a glass slide and or three anthers from each spikelet were maintainers for V20 A. anthesis and fixed in 70% alcohol. Two sterility and were identified as effective were selected from each plant before HPU5101, and CH988 had 100% pollen

IR18482-Plp3-2-5-2, HPU2202, Debal, used as the female parent. Five spikelets Himdhan, R575, Kaladhan, CH1039, were crossed with V20 A, which was were more frequent than restorers.

were identified based on pollen and K39, Himalaya 741, HPU799, spikelet fertility (see table). Maintainers HPU2216, IR9129-263-3-3-3-2-3-2, and

Maintainers and restorers for V20 A and above.

HPU5039-Plp13-4-4-6-3B were classified as partial restorers, which means spikelet fertility is less than 80% but 10% or more.

These findings indicate that effective maintainers are common among rice cultivars adapted to HP's conditions. New CMS lines possessing WA cytoplasm and from different genetic backgrounds can be developed by recurrent backcrossing procedure. Effective restorers for WA cytoplasm still need to be identified among locally adapted rice cultivars to develop heterotic rice hybrids.

Maintainers and restorers for four cytoplasmic male sterile (CMS) lines J. S. Bijral, K. S. Kanwal, and T. R. Sharma, Sher-e-Kashmir University of Agricultural Sciences and Technology, Regional Agriculture Research Station (RARS), R. S. Pura 181102, India

Screening elite breeding lines for effective and genetically diverse maintainers and restorers for different CMS lines is important in developing new CMS lines and productive hybrids.

Short-, medium-, and long-duration rice cultivars were used as pollen parents for crossing with WA-type CMS lines PMS-3 A, PMS-10 A, IR62829 A, and V20 A. The F1 hybrids were evaluated for spikelet fertility during the 1992 wet season (WS).

Rice cultivars with 80% or more spikelet fertility were classified as effective restorers, those with 1-79% as partial restorers, and those with less than 1% as effective maintainers.

IET10485, IET11831, IETl2395, and RR8585 were identified as effective maintainers (see table). IET11831 proved to be an effective restorer for PMS-3 A and PMS-10 A, and a partial restorer for IR62829 A. IET10749 restored the fertility of PMS-10 A but maintained the sterility of PMS-3 A and IR62829 A. IET10485 and IET12395, however, partially restored the fertility of IR62829 A and PMS-3 A, respectively. Only RR8585 restored the fertility of all four CMS lines.

All the test cultivars except


Maintainers and restorers for PMS-3 A, PMS-10 A, lR62829 A, and V20 A. a RARS, R. S. Pura, India, 1992 WS.

CMS lines Variety

PMS-3 A PMS-10 A lR62829 A V20 A

RR8585 R R R IET10485 M – PR IET10749 M R M IET11074 M M M IET11831 R R PR IET12395 PR – M IET12403 M – R IET13152 – M – M Kasturi M M – M R. Basmati M M M M Giza 14 (japonica) M M M –

R – – – – –

–

a R = restorer, PR = partial restorer, M = maintainer.

Identifying maintainers

genetic male sterile (CMS) maintainers and restorers. Panicles were

sterility. The pollen parents and F 1 s were and restorers of cytoplasmic transplanted together to determine

lines for hybrid rice breeding bagged before emergence to avoid outcrossing.

Genetics and Plant Breeding Department,

ogy, Masodha, P. O. Dabhasemar, Faizabad Research Station (CRS), Masodha,

D. M. Maurya, S. P. Giri, and A. K. Singh, Spikelet fertility of F 1 s and parents

N. D. University of Agriculture and Technol- (l0 plants each) was recorded at the Crop

224133, Uttar Pradesh (UP), India Faizabad, during 1987-90 wet seasons

We used 25 varieties as male parents to Table 1. CMS lines used in the study. make 132 crosses with CMS lines V20 A, IR46830 A, IR54752 A, ES18 A, CMS line Origin Source of cytoplasm Madhu A, Pragathi A, Pushpa A, and Mangla A (Table 1) to identify V20A China Wild abortive

maintainers and restorers with varying lR46830 A IRRI Wild abortive

tolerance for agroclimatic stress and lR54752 A IRRI Wild abortive ES18 A India MS 577

resistance to biotic stress.

Pushpa A India MS 577 with 1% iodine solution before crossing PragathiA India MS 577 Pollen from each CMS line was tested Madhu A India MS 577

and found to have a high degree of Mangla A India MS 577

Table 2. Height, duration, and fertility of F1s test crops involving 8 CMS lines. a CRS, Masodha, Faizabad, UP, India, 1987-90 WS.

1987-88 1988-89 1989-90 Variety Height Duration

V20 A lR46830 A lR54752 A ES18 A Madhu A Pragathi A Pushpa A Mangla A

Narendra 1 Narendra 2 Narendra 80 Narendra 118 IR8 IR24 Saket 1 Saket 3 Saket 4 Sarjoo 52 Sattari Manhar Sita Madhuri Jaya Satha 34-36 China 4 Boro Gazipur Boro Mirzapur Jhona 349 Cauvery Govind Mahsuri T100 N22

Dwarf Dwarf Tall Dwarf Dwarf Dwarf Tall Dwarf Dwarf Dwarf Dwarf Dwarf Dwarf Dwarf Dwarf Tall Tall Tall Tall Tall Dwarf Dwarf Tall Tall Tall

Early Early Early Early Medium Medium Early Early Early Medium Early Medium Medium Early Medium Early Early Early Early Early Early Early Late Late Early

PM PR PR R PM R PR

R PR PM PM

PM

R PR

–

–

–

– – – PM – – PR PM

PR PR PM PR

R PR PM PR PR

PM PM PM PM

PR PM PM

PR PR PR

–

–

–

–

– PR

PM PR PR R PR PR R R R R – – – PR

R PM

PM PM PR PR PM PR PM

–

–

PM – – PR PM PM – – PM PM PM PM PM PM PM PM PM PM PM

PM PM

–

– – PM

PM PR PM PR PM PM PM PR PM PM

PM PR

–

– – – – PM PM PM PM PR PR PR PM

PM PM – – – – – PM – – – PM

PM PM PM

–

– – – – PM PM – – PM

PM

PM PM PM PM PM PM PM PM

–

– – – PM PM PM – – – – PM PM PM – PM

PM PM PM PM – – PM PM PM

PM PM

–

– PM – – – – PM

PM PM PM

PM

–

–

a R = restorer, PR = partial restorer, PM = partial maintainer.

(WS). Based on spikelet fertility of F1s, the rice varieties were categorized as effective restorers (80- 100% spikelet fertility), partial restorers (21-79% spikelet fertility), partial maintainers (2-20% spikelet fertility), and maintainers (0-1% spikelet fertility).

Narendra 118, Saket 4, and Satha 34-36 were identified as restorers for V20 A and IR54752 A, and IR24 for IR46830 A (Table 2). No varieties were identified as restorers for ES18 A, Madhu A, Pragathi A, Pushpa A, and Mangla A, and no varieties were identi-

fied as effective maintainers for any CMS lines in this study. Results indicate that CMS source wild abortive was genetically diverse from MS577.

Genotypic differences embryogenic callus

in

formation and plant regeneration in indica rice G. S. Oinam and S. L. Kothari, Botany Department, University of Rajasthan, Jaipur 302004, India

Fifteen indica varieties were used for determining response to embryogenic callus induction and plant regeneration (see table). Embryos were separated from mature, dehusked seeds that had been soaked in sterile distilled water for 24 h at 28 °C. Embryos were cultured on Murashige and Skoog (MS) medium with 3% sucrose and 0.8% agar adjusted

to pH 5.8 and supplemented with 2.5 mg 2,4-D/liter.

responses among genotypes. Calli formed at the scutellar surface after 1 wk of culture. Himalaya 1 did not form any calli. Genotypes formed either embryogenic or nonembryogenic calli or both types. Embryogenic calli were compact, nodular, loosely globular, shiny, dry in appearance, and yellow to cream in color. Nonembryogenic calli were friable in appearance, white to brown in color, and occasionally developed roots.

On the basis of embryogenic callus formation, Chambal, CH1039, HPU5039-Plp13-4-4-6-3B, Himdhan,

We observed variations in culture

HPU5101, HPU2202, and IR18482- Plp3-2-5-2 were selected for regeneration (see table). Four-week-old calli of these genotypes were maintained on MS medium supplemented with 2.5 mg 2,4-D/liter. For plant regeneration, calli (about 1.15 g from each callus) from the second subculture were plated onto MS medium supplemented with three levels of BAP (0.5, 1.0, and 2.0 mg/liter) and NAA (0.05,0.1, and 0.5 mg/liter) in various combinations.

We observed that calli did not regenerate at 0.5 mg BAP/liter and 0.05 mg NAA/liter. At the higher level BAP and NAA combination, a high frequency of regeneration was observed in Chambal, CH1039, and Himdhan


Embryogenic and nonembryogenic callus induction and plant regeneration from indica rice genotypes.

Genotype Callus Callus Calli plated Plants type a growth b for regeneration regenerated c

(no.) (no.)

Chambal CH1039 CH988

HPU2216 HPU5101 HPU2202 Himalaya 1 Himalaya 741 Himdhan

IR36 K39 Kaladhan R575

HPU5039-Plp13-4-4-6-3B

IR18482-Plp3-2-5-2

E +++ (50) E +++ (50) NE ++ (25) E + (12) NE ++ (37) E ++ (17) E +++ (58) NR – NE E +++ (42) E ++ (8) NE + (25) NE + (37) NE +++ (75) NE ++ (8)

– + (25)

40 48

48

52 32

–

–

– –

44 32 – – – –

Green Albino

219 181 588 –

– – 72 – – –

130 72

– –

– – – –

297 – – – – – – – – – – –

a Callus Induction medium = MS + 2.5 mg 2,4-D/liter. E = embryogenic callus, NE = nonembryogenic callus, NR = no response. b + = poor, ++ = moderate, +++ =good to excellent, – = not attempted. Values in parentheses indicate the percentage of response among replicates. c Plant regeneration medium = MS + 1.0 mg BAP/liter and 0.1 mg NAA/liter.

(see table). HPU5039-Plp13-4-4-6-3B, HPU2202, and HPU5101 regenerated into green plantlets but at a lower frequency. IR18482-Plp3-2-52 did not regenerate. Chambal, CH 1039, and Himdhan were considered more responsive than the others to callus formation and plant regeneration. Chambal had a high frequency of albino plants.

callus formation and plant regeneration ability vary among indica rice genotypes.

The results indicate that embryogenic

Effect of interaction between genotype and culture medium on callus induction and plant regeneration of anther culture of Vietnamese indica rice ( Oryza sativa L. ) M. Don Nguyen, Food Crops Research Institute, Hal Hung, Vietnam, and F. J. Zapata, IRRI

We evaluated the response of 12 Viet- namese indica rice genotypes (including F 1 , promising lines, and varieties) to anther culture using several callus induction media (CIM) and plant regeneration media (PRM). Anther culture can complement the rice breeding program in Vietnam by offering the advantage of rapid achievement of homozygosity.

uninucleate to early binucleate stage of development were plated on CIM G1, Fj, and L8 (Table 1) at a density of 1.5 anthers/ml of medium. The plated anthers were incubated in the dark at 25±1°C. Callus induction percentage was recorded 2 mo after culture and calculated as number of callus-producing anthers relative to total anthers plated. We transferred calli of 1-2 mm diameter to

Anthers with microspores at the mid-

Table 1. Constituents of callus induction media.

Constituent Medium (mg/liter)

G1 Fj

KNO 3 2830 3150 (NH 4 ) 2 SO 4 463 220 KH 2 PO 4

CaCI 2 • 2H 2 O MnSO 4 • 4H 2 O ZnSO 4 • 7H 2 O

KI

MgSO 2 • 7H 2 O

H 3 BO 3

CuSO 4 • 5H 2 O CoCI 2 .•6H 2 O NaMoO 4 • 2H 2 O Na 2 EDTA FeSO 4 • 7H 2 O Glycine Thiamine-HCI Pyridoxine-HCI Nicotinic acid Lactalbumin Casein hydrolysate Inositol

Naphthalene acetic acid Sucrose Agar

2,4-D

PH

170 185 440

4.4 1.5 6.2 0.83 0.025 0.025 0.025

37.25 27.85

2.0 2.5 2.5 2.5 –

500.00 100.0

2.0 2.5

40000 8000

5.8

540 185 150

22.3 10.0

6.0 1.0 0.025 0.025 0.025

37.25 27.85

2.0 2.0 2.0 2.0

500.0 100.0

0.5 2.5

–

40000 8000

5.8

L8

3000 –

540 185 150

22.3 10.0

6.0 1.0 0.025 0.025 0.025

37.25 27.85

2.5 5.0 3.0

500.0

100.0 0.5 2.0

–

40000 8000

5.8


In Pusa 169, unfilled grains coupled with poor and average grain accounted for 90% of total grains at 15 DAPE, but dropped to 71% at maturity.

Good plus HDG grains made up 46% of total grains/panicle at 15 DAPE in Jaya and 65% at 30 DAPE. The appearance of this high percentage of good plus HDG at 15 DAPE indicates that this is a genotypic character distinct from large grain size and high total grains/panicle.

Many HDG appeared as early as 15 DAPE in short-duration cultivars such as Rasi and Pusa 2-21. HDG was barely evident up to 30 DAPE in medium- duration cultivars, such as Pusa 169 and Pusa 743. These results suggest that grain filling may be a predetermined phenom- enon or a genotypic character.

Good and high density grains (HDG) constituted 67% of total grains in Rasi at 15 DAPE (see table). This percentage increased towards maturity, although at 25 DAPE it nearly stabilized at 77% of the total grains/panicle. Unfilled grains constituted 16% of the total as early as 15 DAPE and declined gradually towards maturity.

In Pusa 2-21, HDG made up about 55% of the total grains at 15 DAPE; this percentage remained almost stable until maturity.

Pusa 743 has good grain type. The occurrence of good grains/panicle was almost stable around 20 DAPE, although at 15 DAPE, good grade grains were only 8.8% of the total. HDG/panicle was 9.2% at 20 DAPE, dropped, and then climbed to 10% at 35 DAPE.

11 PRM for plant regeneration, which was calculated as number of calli producing green plants relative to total calli plated.

Genotype and medium interaction showed significant effect on callus induction (Table 2). All genotypes responded with callus induction being genotype- and medium-dependent. Callus induction ranged from 1.8% in IR64DR2588-1-3-2 on G1 medium to 27.9% in Nep Hoa Vang on L8 medium. Among the three CIM tested, L8 gave the highest average callus induction of 19.5%, followed by G1 and Fj.

Green plant production ranged from 13.3% in IR64DR2588-1-3-2 to 25.4% in IR8/828//Nep Ga Gay (Table 2). Significant effects of the interactions among genotypes, CIM, and PRM were observed. Among the PRM used, however, M6 medium (Murashige and

regeneration b

Yield potential

Table 2. Interaction between genotype and medium on callus induction and plant regeneration of indica rices.

Genotype Callus induction a (%) Green plant

Fj G1 L8 (%)

C15/Nep Hoa Vang (F 1 ) 4.8 efghijk C15/Nep Ga Gay (F 1 ) 5.5 defghi IR1529-680-3-2/Pelita (line) 7.0 cde IR8/DU//IR529 (line) 4.9 efghijk IR8/828//Nep Ga Gay (line) 3.8 hijklmn IR8/DU//C4-63///IR1569 (line) 5.2 defghi 184/IR8 (line) 3.7 hijklmn lR64/IR2588-1-3-2 (line) 2.7 mno C10 (variety) 5.7 cdefgh Xuan So 4 (variety) 13.2 a Nep Hoa Vang (variety) 7.8 bc Nep Ga Gay (variety) 4.6 fghijkl

13.0 cd 15.6 c 17.7 cd 15.2 bc 15.4 c 15.1 de 19.4 ab 25.4 ab 13.3 f 16.8 abc 22.5 b 17.9 cd

5.6 f 17.1 c 25.4 a 18.9 ab 22.1 b 18.0 c

6.8 ef 11.4 d 21.7 b 1.8 g 16.4 c 13.3 f

16.7 abc 11.2 d 16.3 cd 19.5 a 24.1 ab 23.0 ab 18.7 ab 27.9 a 14.9 ef 13.3 cd 24.6 ab 17.5 cd

a Means in a column with the same letter are not significantly different at the 5% level by DMRT. Means among CIM in a row are separated using LSD0.05 = 2.59. b The response for each variety is the mean of 11 PRM.

Skoog basal supplemented with 1.0 plants. A total of 3211 green plants were mg naphthalene acetic acid/liter and 8 regenerated from these materials; 40% of mg kinetin/liter) produced the most green the regenerants produced seeds.

Different grades of grain occur during grain filling in short- and medium-duration rice N. M. Chau and S. C. Bhargava, Plant Physiology Division, Indian Agricultural Research Institute (IARI), New Delhi 11001 2, lndia

We graded grain during grain filling in five rice cultivars in 199 1 kharif (monsoon) season at IARI. Panicles emerging synchronously from the main tillers were labeled. Five panicles per cultivar were collected at a 5-d interval from 15 to 35 d after panicle emergence (DAPE). Panicles were threshed and graded by specific gravity method.

~

Number and percentage of different grades of grain/panicle at successive growth stages during grain filling. IARI, New Delhi, India, 1991 kharif.

High density grains/ panicle

Cultivar no. % b

Rasi 15 80 (58.4) 20 96 (62.3) 25 91 (64.5) 30 59 (48.8) 35 104 (61.9)

Good grains/ Av grains/ panicle panicle

no. % no. %

12 (8.8) 8 (5.8)

18 (12.8) 7 (5.0)

31 (18.5) 7 (4.2)

12 (7.8) 8 (5.2)

43 (35.5) 4 (3.3)

Poor grains/ panicle

no. %

16 (11.4) 16 (10.4)

8 (5.7) 4 (3.3)

11 (6.5)

Unfilled grains/ panicle

no. %

21 (15.6) 22 (14.3) 17 (12.0) 11 (9.1) 15 (8.9)

Total grains/

DAPE a panicle

(no.)

137 154 141 121 168

continued on next page


From page 11

Cultivar DAPE a

Pusa 2-21 15 20 25 30 35

High density grains/ Good grains/ panicle panicle

no. % b no. %

83 (55.2) 2 (1.3) 105 (59.3) 4 (2.3) 94 (59.9) 16 (10.2) 73 (50.0) 13 (8.9) 81 (51.3) 30 (19.0)

Av grains/ panicle

no. %

4 (2.7) 4 (2.7)

12 (7.6) 11 (7.5) 15 (9.5)

Poor grains/ panicle

no. %

10 (6.9) 32 (18.2) 26 (16.6) 35 (24.0) 25 (15.8)

Unfilled grains/ panicle

no. %

51 (33.9) 32 (18.1)

14 (9.6) 9 (5.8)

7 (4.4)

Total grains/ panicle

(no.)

150 177 157 146 158

Pusa 743 15 0.3 (0.2) 15 (8.8) 35 (20.6) 48 (28.2) 72 (42.3) 170

25 2 (1.3) 74 (47.1) 38 (24.2) 18 (11.5) 25 (15.9) 157 152

30 2 (1.4) 72 (50.7) 3 (19.1) 9 (6.3) 32 (22.5) 142

20 14 (9.2) 78 (51.3) 7 (4.6) 24 (15.8) 29 (19.1)

35 13 (10.0) 59 (45.7) 17 (13.2) 15 (11.6) 25 (19.4) 129

Pusa 169 15 0.3 (0.2) 19 (10.3) 32 (17.4) 40 (21.7) 93 (50.5) 184

25 1 (0.5) 27 (14.4) 46 (24.5) 27 (14.4) 87 (46.3) 188 30 1 (0.7) 25 (17.6) 45 (31.7) 25 (17.6) 46 (32.4) 142

20 2 (1.2) 50 (30.7) 12 (7.4) 15 (9.2) 84 (51.5) 163

35 7 (3.6) 50 (25.4) 30 (15.2) 46 (23.4) 64 (32.5) 197

Jaya 15 12 (7.2) 65 (39.2) 22 (13.3) 18 (10.8) 49 (29.5) 166

25 34 (17.7) 85 (44.3) 16 (8.3) 27 (14.0) 30 (15.6) 192 30 33 (18.6) 82 (46.3) 17 (9.6) 33 (18.6) 12 (6.8) 177

20 16 (8.7) 73 (39.4) 27 (14.8) 21 (11.5) 46 (25.1) 183

35 41 (22.0) 76 (40.9) 16 (8.6) 33 (17.7) 20 (10.8) 186

a DAPE = d after panicle emergence. b Numbers in parentheses indicate percentage of total grains/panicle.

Colombia 1 carries the resistance genes

Using pedigree analysis to identify sources of resistance to rice hoja blanca virus (RHBV) F. Cuevas-Perez, Apartado Aereo 67-13, Cali, Colombia; C. Ventura-Flores, Universidad Nacional Pedro Ruiz Gallo, Chiclayo, Peru; and F. Correa-Victoria, International Center for Tropical Agriculture (CIAT) Rice Program, Cali, Colombia

RHBV is the only virus disease of rice in the western hemisphere. It is restricted to Latin America. The insect Tagosodes orizicolus (Muir) transmits RHBV. To identify the original sources of resistance, we searched the literature for varieties and lines reported as resistant or moderately resistant to RHBV and conducted pedigree analyses.

Cultivars reported to have some degree of resistance, their parents with unknown reaction, and some landraces contributing to the pedigrees were evaluated in the greenhouse for their

reaction to RHBV. Cages (2 × 1 × 1 m) with capacity for 180 pots, each containing 10 plants, were used. Ten pots with 15-d-old plants of each genotype were randomly distributed within the cage and exposed for 5 d to a colony of the insect vector with at least 70% of the individuals carrying the virus. Each plant was assessed for disease symptoms 15 d after exposure.

Eight of the nine varieties or lines previously reported as resistant to RHBV showed infections of less than 30%, which is the accepted resistance level (see table). The susceptible reaction of line IR1721-146-4-3 was reconfirmed by the performance of its parents, Oryza nivara and IR24, and its other ancestors, B5580A1-15 and Sigadis (parents of IR127, used to develop IR24), suggesting the lack of genetic sources of resistance.

One accession of Agostano and Balilla and both of Blue Rose and Takao Iku 18 showed a reaction similar to that of the resistant check. It can be inferred that

of Takao Iku 18 because its other parent, Napal, was reported as susceptible when released. Genes of Agostano (and possibly Balilla and Blue Rose) could be responsible for the resistance of Dia- mante, and ICA10 could be a source of the resistance genes coming from PI215936. Lacrosse’s pedigree analysis showed that its ancestors were Colusa, Blue Rose, Shoemed, and Fortuna; the observed resistance could come from the first two varieties. Doing the same exercise with the Oryzica varieties, Takao Iku 18 appears to be the most probable source of resistance. For Llanos 4, Taichung 6.5 and Makalioka might have contributed resistance genes through IRAT122 (Chianan 8/Makalioka).

Pedigree analysis can be used to identify major sources of resistance and to help select parents that enable diverse genes to be incorporated into a breeding program. Pedigree analysis reduces the crosses needed to determine the relationship among the resistance sources identified.


Pest resistance — diseases

Description of rice varieties and lines previously reported to be at least moderately resistant to RHBV, their ancestors, and Percentage of Plants with RHBV symptoms.

Name Origin Designation Cross Reaction to RHBV

(% of affected plants)

Colombia 1 Diamante ICA10 INIAP415

Lacrosse Oryzica 1 Oryzica Llanos 4 Oryzica Llanos 5

–

Agostano Agostano Balilla Balilla Blue Rose Blue Rose IR24 Oryza nivara PI215936 PI215936/CI9214 Takao Iku 18 Takao Iku 18

Colombia Chile Colombia Ecuador IRRI USA Colombia Colombia Colombia

Italy Hungary Italy Italy USA USA Philippines India China USA China China

Varieties and lines T319E-2M-2M-lM-lM Napal/Takao Iku 18 P1-2-2-2-1 Agostano/Blue Rose//Balilla T112D-7P-5T British Guyana 79/(PI215936 × CI9124) P1042-2-3-1B P738-137-4/P723-40-3-1 lR1721-146-4-3 lR24*3/ O.nivara Sel. no. 250-121 2913A5-1-3/ALll-l P1429-8-9M-16 P1223/P1225 P5413-8-3-5-11 CR 1113/1RAT 122//Colombia1/P1274-6-8M CT5747-24-5-4-2 Colombia l/P1274-6-8M*2//P2060F4-25-2

Parents Acc. 3135 Acc. 9334 Ace. 3098 Ace. 3107 Ace. 1731 Ace. 1732

Acc. 101508 Acc. 146 Ace. 11394 Ace. 3037 Ace. 6923

– – – – –

lR661-1-140-3 –

IR8/IR127-2-2 – – – – –

Other ancestors B5580AL-1-15 (CP-SLO) USA Acc. 6993 Century Patna/SLO 17 Chianan 8 China Acc. 90 Taichung 65//Mitsui/Oloanchu Colusa USA Acc. 1714 Fortuna USA Acc. 1708 Makalioka Madagascar – Sigadis Indonesia Acc. 5324 Bluebonnet/Benong Taichung 65 China Acc. 79 Shinriki/Kameji

– – –

Colombia 1 (resistant) Colombia Bluebonnet 50 (susceptible) USA

Checks T319E-2M-2M-lM-lM Napal/Takao Iku 18 – Rexoro/Fortuna

3.9 3.8 2.2

28.0 72.9

7.4 23.6

4.4 0.8

0.7 61.7 88.3

6.4 8.3 0.9

78.5 97.9

3.7 6.1 5.7 6.6

83.3 19.8

3.3 62.5 13.0 75.6

2.0

5.0 83.6

Detection of rice bacilliform virus asymptomatic

tungro (RTBV) in

leaves of tungro-infected rice plants by polymerase chain reaction (PCR) S. R. Venkitesh, R. W. Briddon, and P. G. Markham, Virus Research Department, John lnnes Institute, John lnnes Centre for Plant Science Research, Colney Lane, Norwich NR4 7UH, United Kingdom

We have detected the presence of RTBV and rice tungro spherical virus (RTSV) in infected TN1 rice plants by antibody fragment F(ab’) 2 enzyme-linked immunosorbent assay (ELISA) 1 wk after

inoculation. Green leafhoppers Nephotettix virescens (Distant) were given an acquisition access period of 72 h on plants infected with both rice tungro disease (RTD) viruses and a transmission access period of 24 h on 2-wk-old rice seedlings (2 d-leaf stage). Infected plants were grouped, following F(ab’) 2 ELISA tests, for the presence of RTSV (S) or RTBV (B) alone or RTD (B+S) in the newly emerged leaf. RTD- infected rice seedlings were dissected 1 wk after inoculation (3 d-leaf stage) into individual leaves, stem apex, and roots. Each part was then tested for the presence of RTSV or RTBV by F(ab’) 2 ELISA and for the presence of RTBV DNA by PCR.

The presence of viral coat proteins varied in different plant parts (Fig. 1). One wk after inoculation, detectable amounts of RTSV and RTBV viral coat proteins were found in the newly emerged leaf (leaf 3), stem apex, and roots.

Among the symptomless leaves (those which emerged before the insect inoculation), very few (3 out of 20) contained detectable amounts of RTSV coat proteins. Neither virus was detectable by F(ab’) 2 ELISA in most of them. Two plants showing a typical pattern of virus distribution by F(ab’) 2 ELISA (Fig. 1c) were dissected and tested by PCR (Fig. 1d). PCR showed the presence of RTBV DNA in symptomless leaves of these plants.


1. Viral coat proteins in different plant parts as detected by ELSA and PCR.

~~ ~

In RTD-infected plants, RTBV DNA detecting the presence of RTBV in symp- was detected in all parts of the infected tomatic and symptomless plant tissue. plant by PCR. The PCR technique is much Oligonucleotide primers were designed more sensitive than F(ab')2 ELISA for to the published sequence of RTBV. The

2. PCR products resolved in 1% agarose gel stained with ethidium bromide. Markers: lane 1 = uninfected extract; lane 2 = no DNA; lanes 3, 4, 5, 6, and 7 = extracts from stem apex, dissected leaves no. 3, 2, 1, and roots.

a 1 and 2 = leaves emerged before Insect Inoculation; 3 = newly emerged leaf after Insect Inoculation. NV = no virus (es) detected; B = RTBV; S = RTSV,

b 20 RTD-infected plants were dissected into five parts (leaves 1, 2, and 3, stem apex, and roots). c Out of 20 RTD-infected plants, dissected parts of two plants were tested by PCR

B+ S= RTBV+ RTSV

plus strand primer (5'GAG-

and minus strand primer (5'-GGA-

were complementary to regions of the P12 and P194 open reading frames, respectively, and amplified an 827-bp fragment of RTBV DNA. PCR reaction conditions were standard with a typical input of 100 ng of total nucleic acid extract of rice plant tissue and 50 nM primers. PCR reaction products were resolved on 1% agarose gels stained with ethidium bromide (Fig. 2).

CGCTGATTACCCAACTTTCAAGG-3')

GTAGAATACTCCACAACCGGCG-3')

Evaluation of resistance to bakanae and foot rot disease M. A. Gill, S. I. Yasin, T. Z. Khan, O. Ahsanullah, and M. A. Butt, Rice Research Institute, Kala Shah Kaku, Lahore, Pakistan

Bakanae and foot rot disease, caused by Fusariwn moniliforme Sheld., appeared in patches on Basmati 385 in farmers’ fields during 1989. The disease developed further because no control measures were adopted. None of the Basmati 385 fields surveyed during 1991 were disease-free in Sheikhupura, Gujranwala, and Sialkot districts, which make up the traditional rice-growing area in the Punjab. Disease incidence ranged from 5 to 90%.

To overcome the disease problem through resistant varieties, 10 fine-grain and 10 medium-grain varieties/lines were screened in the greenhouse during 1990-92. Soil was infected with the diseased plant debris and F. moniliforme culture grown on wheat grains. During 1990 and 1992, the inoculum potential

Reaction of rice varieties/lines to bakanae and foot rot disease under greenhouse condition.

Variety

Fine grain Basmati 370 Basmati 6129 Basmati 198 Basmati 385 4048 1053-32 4439 1053-1-2 33608 Basmati C-622

Medium grain Shadab Iran

DR83 Jhona 349 IR8 IR6 IR9 KS282

PK3303-15-1

PK1399-12-1-1-0-6

Disease incidence (%)

1990 1991 1992

16.7 92.4 8.3 77.0 0.0 38.5

58.3 84.7 50.0 100.0

– 92.4 – 15.4 – 84.7 – 100.0

16.7 100.0

15.40 69.20 54.6 46.2 61.5

0.0 0.0 7.7 7.7

46.2

0.0 0.0 0.0 – 92.4 30.8

0.0 0.0 0.0 30.8 0.0 – 100.0 38.5

0.0 0.0 0.0 7.7 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7.7 0.0


was kept low, while it was doubled in 1991 to test the resistance in the materials. Seedlings were transplanted at 40 d. Elongation/mortality of the seedlings started 2 wk later. Data were recorded 1 1/2 mo after transplanting (see table).

Among the fine-grain varieties/lines,

Pathological constraints on hybrid rice production technology R. C. Sharma, G. S. Sidhu, T. S. Bharaj, and H. L. Sharma, Department of Seed Science and Technology (DSST), Punjab Agricultural University, Ludhiana 141004, India

Preliminary observations during 1989 kharif (monsoon) season revealed a higher incidence of Fusarium sheath rot (FShR), caused by Fusarium moniliforme Sheld., and kernel smut Tilletia barclayana (Bref.) Sacc. & Syd. on cytoplasmic male sterile (CMS) lines than on their corresponding maintainers. We have since been observing these diseases under natural field conditions at

Percent incidence of kernel smut on CMS lines and hybrid rice and their corresponding maintainers, restorers, and inbred rice varieties. a Kapurthala, India, 1991.

Incidence Entry Incidence on corre-

(%) sponding maintainer

line (%)

CMS line PMS1 A PMS2 A PMS3 A PMS4 A PMS5 A PMS6 A PMS7 A PMS8 A PMS9 A PMS10 A

Hybrid rice PAU2 A/1126-1-1 PMS8 A/1106-6-2 PMS8 A/31432 PMS8 A/1126-15-3

9.5 10.7 15.0 2.9 4.8 0.9 4.6

13.9 0.5 7.5

5.8 10.2 5.1

10.0

0.7 0.5 0.5 0.6 1.2 0.8 1.0 0.5 1.0 0.3

a Kernel smut incidence was 0.05-1.7% on restorer lines and 0.08-0.68% on inbred rice varieties (grown next to CMS lines) PR106, PR108, PR109, Jaya, Basmati 370, and Basmati 385. Incidence in Pusa Basmati No. 1 was 1.3%.

Basmati 370,4439, 1053-1-2, 1053-32, and 33608 showed resistance under low inoculum potential and high incidence under high inoculum potential. These varieties can be grown in fields with low soil infestation. Basmati 385, Basmati 6129, and 4048 are susceptible under all

Regional Rice Research Station, Kapurthala, and at DSST research farms.

To assess FShR severity, we randomly selected 100 tillers at five nearly equally spaced spots in a seed production plot. Disease intensity was scored on a 0-4 scale where 0 = no infection and 4 = maximum infection where no panicle emerged.

5,000 seeds of each sample in sodium hydroxide (0.2%) solution for 20 h at 25°C. Seeds were then washed thoroughly and spread out on blotting paper for examination.

more severe on CMS lines and hybrid rice compared with their corresponding maintainers, restorers, and inbred rice varieties (see table). Kernel smut incidence was as high as 9.5-15.0% in CMS

We detected kernel smut by soaking

Kernel smut and FShR were generally

High-yielding, brown planthopper (BPH)-resistant varieties developed at Maruteru, Andhra Pradesh (AP), India

Y. Suryanarayana, P. S. Rao, N. S. R. Reddy, K. R. K. Murthy, P. S. N. Murthy, I. N. Rao, and V. R. Rao, Agricultural Research Station (ARS), Maruteru 5341 22, AP, India

Severe BPH damage that led to hopperbum was noticed in AP in 1976. Since then, BPH has been a recurring problem in both wet (WS) and dry (DS) seasons in rice areas of East and West Godavari, Krishna, and Guntur districts. Yield losses due to BPH have ranged from 10 to 100%.

Developing BPH-resistant varieties is environment friendly and offers economic savings for farmers. Resistant donors ARC6650 and ARC5984 and popular high-yielding local variety

conditions and should be avoided. Medium-grain varieties/lines — IR6, IR8, IR9, Shadab, KS282, PK3303-15-1, and PK 1399-12-1-1-0-6—were highly resistant and can be grown successfully in severely infested fields.

lines. FShR intensity was 33.1-42.4% in CMS lines and 15.4-19.3% in maintainers, restorers, and inbred rice varieties. Panicles of CMS lines are enclosed in sheaths longer than panicles of other types of rice plants, thus provid- ing favorable conditions for disease development. Nonexsertion of CMS panicles was 11.2-16.8% compared with 2.4-5.8% in the other groups.

The high degree of susceptibility of CMS lines to FShR and kernel smut might become a limiting factor in hybrid seed production and perhaps commercial hybrid yields. Transferring genes imparting resistance or partial resistance to kernel smut to CMS lines might be useful. We are exploring the use of chemical seed treatment and foliar sprays to check the disease.

Sowbhagya were used in a breeding program for BPH resistance that began in the late 1970s at ARS. Selection was exercised in segregating populations of crosses Sowbhagya/ARC6650 and Sowbhagya/ARC5984, resulting in the release of six promising BPH-resistant varieties during 1986-91 (see table).

Farmers of Krishna and Godavari deltas are growing these varieties during WS on 1 million ha. They were proven superior in several yield evaluation trials at state and national levels, including the All India Coordinated Trials.


Characters and BPH resistance score for varieties a bred at ARS, Maruteru, AP, India.

Yield Crop Plant Panicles Test Seed Grain Reaction Year of Variety Parentage (t/ha) duration height (no./m 2 ) weight dormancy type b to BPH release

(d) (cm) (g) (wk) in field c

MTU5249 (Vajram) ARC6650

MTU5293 Sowbhagya/ 6.0 165 115 364 21.1 2 MS 2.0 1986 (Prathiba) ARC6650

MTU2067 Sowbhagya/ 6.5 155 110 390 21.5 4 MS 2.0 1988 (Chaitanya) ARC5984

MTU2077 Sowbhagya/ 6.5 155 110 405 19.7 4 MS 3.0 1989 (Krishnaveni) ARC5984

MTU5182 Sowbhagya/ 6.0 150 110 350 20.7 3 MS 2.0 1991 (Nandi) ARC6650

MTU4870 Sowbhagya/ 6.0 150 110 384 22.2 5 MS 2.0 –

Sowbhagya/ 6.0 150 100 343 21.0 4 MS 3.0 1986

ARC6650

Swarna (susceptible check) 150 105 360 20.0 3 MS 8.0 –

a All varieties have white kernels. b MS = medium slender. c Scored using Standard evaluation system for rice scale of 0-9.

O. australiensis and O. brachyantha allowed greater reproduction of the

Susceptibility of wild rice species to nematode Meloidogyne graminicola E. B. Gergon and J.-C. Prot, IRRI

We tested 15 accessions of 10 wild rice species to locate sources of resistance to the rice root knot nematode, M. graminicola. Eight-day-old seedlings of Oryza australiensis from Australia; O. barthii and O. brachyantha from Africa; O. latifolia from South and Central America; and O. minuta, O. nivara, O. officinalis, O. rhizomatis, O. ridleyi, and O. rufipogon from Asia were infested with 1,000 2d-stage juveniles of M. graminicola from a culture maintained on cultivar IR72 in a greenhouse.

The experiment was laid out in a randomized complete block design, with six replications, in a greenhouse using 60-cm long, 10-cm diameter PVC tubes filled with 6 kg of sterilized soil. Six plants of each accession were grown under upland conditions and watered daily. Roots were collected 48 d after infestation. Second-stage juveniles were extracted by placing the roots in a misting chamber for 7 d. Results were analyzed

using ANOVA and DMRT. parasite than did the other accessions. We M. graminicola reproduced on all of the will need to test other wild rice species

wild rice species tested, indicating that and accessions of species previously none were resistant to the parasite (see tested to determine whether absolute table). Different degrees of susceptibility, resistance to rice root knot nematode however, were observed. exists in the genus Oryza.

Average number of M. graminicola 2d-stage juveniles recovered from 1 g of root.

M. graminicola Wild rice species juveniles tested (accession no.) recovered from

1 g of root a

(av no.)

O. australiensis (100882) O. barthii (101827) O. brachyantha (101232) O. latifolia (100914) O. latifolia (105141) O. latifolia (105142) O. minuta (101141) O. nivara (103422) O. nivara (103839) O. officinalis (100896) O. rhizomatis (105432) O. ridleyi (100821) O. rufipogon (100692) O. rufipogon (103817) O. rufipogon (104453)

10236 c 1672 a 5855 b

761 a 505 a 469 a

1362 a 1024 a 3209 ab

238 a 650 a 452 a 872 a 965 a 396 a

a Av of six replications. Averages followed by the same letter are not significantly different at the 5% level by DMRT.


Pest resistance—other pests

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Comparative studies of germination and seedling growth of some salt-tolerant selections at different salinity levels S. Gupta, Field Crop Research Station, Burdwan, West Bengal, lndia

Ten salt-tolerant selections, identified and developed in the IRRI-India Collaborative Program at Kakdwip, were tested for their tolerance for high salinity during germination and seedling stages.

These included eight accessions, two traditional improved selections (Hamil- ton, from local variety Nona Bokra, and Matla, from local variety Getu) widely grown under tidal wetland situation, a resistant check (SR26-B), and a susceptible check (Jaya).

We arranged 50 seeds of each line on glass plates and conducted a germination test following the method of Dasgupta et al (1976). In separate procedures, the bottoms of the glass plates were immersed in one of the

following treatments: distilled water (Tl), saline water from a local estuary diluted with distilled water to have an electrical conductivity (EC) of 7.8 dS/m (T2), and saline water from the estuary without dilution that had an EC of 14.6 dS/m (T3). The experiment was replicated three times.

characters were analyzed statistically (see table).

Germination was significantly reduced in only two entries-IR52712- B-B-33-B-B-CN-3 and IR49737-B-B- 29-B-B-CN-1-when salinity was increased from 0 to 7.8 dS/m. Germina- tion was significantly reduced in selections IR527 12-B-B-33-B-B-CN-3,

B-B-29-B-B-CN-1, and SR26-B at higher salinity (EC 14.6 dS/m). Germi- nation percentage in other entries remained almost constant across salinity levels.

Significant increase in root length at 7.8 dS/m was observed in IR4630-22-5-

and IR52713-B-B-19-B-B-CN-4, but at

Effects of salt concentrations on plant

IR52713-B-B-19-B-B-CN-4, IR49737-

1-CN-940, IR5 1194-CN-930-44-16-B,

14.6 dS/m, root growth was significantly reduced in IR52713-B-B-19-B-B- ZN-4. Root growth was almost unaf- Fected-even at the high salinity level- in Hamilton, Matla, and IR52712-B-B- 33-B-B-CN-3. Root growth decreased steadily in IR31376-1-2-2-2-2-4-1 with the increase in salinity level.

Shoot length generally decreased with increasing salinity; this tendency was most conspicuous in Jaya and IR31376-1-2-2-2-2-4-1. Shoot growth remained almost unaffected across salinity levels in other entries.

Dry matter accumulation in general was not affected by salinity, except in

B-B-19-B-B-CN-4, and Hamilton. In LR49737-B-B-29-B-B-CN-1 and SR26-B, it increased constantly with the increase in salinity.

IR4630-22-5-1-CN-940 was com- paratively more tolerant of high levels of salinity during germination and seedling growth stages than the other entries.

LR52712-B-B-33-B-B-CN-3, IR52713-

Comparative performance of entries under different salinity levels a during germination and seedling stages.

Comparative performance with respect to character

Entry Germination Mean root length Mean shoot length Dry wt per plant Normal seedlings

(%) (cm) (cm) (mg) germinated (%)

T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3 T1 T2 T3

IR13198-66-2-CN 939-2-1 lR4630-22-5-1-CN-940 lR51194-CN-930-44-16-8 IR41213-6-6-3-B-6-CN-107 lR31376-1-2-2-2-2-4-1 IR52712-B-B-33-6-6-CN-3 IR52713-6-B-19-6-B-CN-4 lR49737-6-6-29-6-B-CN-l Hamilton Matla Jaya (susceptible check) SR26-B (resistant check)

CV (%) for treatments CV (%) for selections LSD (treatments) at P (0.01) LSD (selections) at P (0.01)

84.4 88.1 84.1 93.5 90.4 81.8 91.0 94.3 92.2 95.2 89.1 93.1

82.2 89.3 87.2 92.7 87.7 74.0 91.0 72.8 89.5 91.6 90.5 88.4

2.2 3.0 7.1 5.4

81.2 86.0 82.2 92.7 86.0 65.0 82.5 69.9 87.3 90.2 82.2 83.9

12.1 10.2 8.9

16.8 19.1 6.9 6.8 8.6

15.3 15.2 12.1 16.3

14.7 16.3 14.4 13.7 15.7 8.3

11.2 9.8

14.2 18.7 13.4 17.3 9.3

16.6 4.4 4.4

11.2 14.3 15.7 13.7 12.4

9.9 6.4 7.4

15.8 14.9

9.1 13.4

6.5 6.8 6.2

11.3 12.6

7.0 6.3 5.7

11.6 9.0 7.5 9.4

6.8 8.1 8.7 9.6

10.5 6.8 6.5 5.6

11.2 12.0

5.1 9.8

10.4 13.6

3.1 2.4

5.4 8.2 7.8 9.5 8.2 5.1 4.9 4.8 9.7 8.1 3.6 7.3

12.83 14.10 12.60 32.60 27.07 21.09 20.23 28.23 19.80 30.77 38.23 44.63

14.87 16.03 14.40 39.43 25.87 21.70 20.17 31.33 12.33 32.93 36.70 46.97

8.7 10.5

8.1 5.5

11.67 13.70 12.33 32.20 22.70 12.03

9.50 32.46 10.27 32.80 29.77 49.37

80.3 85.7 84.3 89.6 81.6 71.8 92.0 83.4 76.6 80.5 79.9 78.1

75.3 83.5 84.6 78.0 84.5 62.7 84.7 65.6 77.2 83.1 74.3 74.6

3.7 2.9

10.3 4.5

41.6 71.0 55.4 69.2 77.4 54.0 56.4 68.1 58.4 67.7 60.9 62.2

a T1 = distilled water, T2 and T3 = saline water collected from local estuary with EC value of 7.8 and 14.6 dS/m, respectively.


Stress tolerance—advance soils

ADT41 (JJ92), a short- duration Basmati rice for Tamil Nadu, India S. Vairavan, S. Arumugachamy, P. Vivekanandan, A. P. M. Kirubhakaran Soundararaj. S. Giridharan, S. Palanisamy, A. Abdul Kareem, and S. Chelliah, Tamil Nadu Agricultural University, Coimbatore, India

Basmati rices are reputed for their aroma and quality. Traditional Basmati rices are tall, low-yielding, photoperiod- sensitive, and susceptible to insect pests, diseases, and lodging. High-yielding Basmati varieties are cultivated in northwestern India.

ADT41, popularly known as JJ92, is a semidwarf Basmati developed at Tamil Nadu Rice Research Institute (TNRRI), Aduthurai. It is a selection from a dwarf mutant of Basmati 370. It matures early (110 d), has acceptable Basmati rice quality, and is nonlodging and photoperiod-insensitive. It is moderately resistant to blast but susceptible to brown planthopper, leaffolder, bacterial blight, and bacterial leaf streak.

ADT41 yielded a mean of 4.2 t/ha in 44 trials at research stations and on farms (Table 1). The highest grain yield obtained was 10.6 t/ha in the Adaptive Research Trial, Kodumudi.

Most of the grain quality characteristics of ADT41 are comparable with those of Pusa Basmati 1, a high-yielding variety grown in northern India. ADT41 conforms to the minimum acceptable standards for Basmati quality (Table 2),

Table 2. Morphological and grain quality characters of ADT41 (JJ92).

Character ADT41 Pusa Basmati 1 acceptable Basmati minimum

standard

Plant height (cm) 95 Days to maturity (d) 110 1,000-grain wt (g) 24.2 Head rice recovery (%) 55.7 Grain length (mm) 8.3 Grain length -breadth ratio 4.3 Grain length after cooking (mm) 11.4 Grain elongation ratio 1.4 Volume expansion (g/g) 4.6 Gelatinization temperature a 6

Aroma Mild (alkali score)

90 130

18.8 44.8

7.4 4.2

12.0 1.7 4.5 2

Mild

>40.0 6.5 3.5

10.0 >1.5

3.7 5-6

Fine, appealing smell

a Scored using the Standard evaluation system for rice.

with grain length and L-B ratio much higher than the minimum standards. Cooked rice length averaged 11.4 mm. The mildly scented rice is soft and not sticky, making it well-suited for specialty rice products.

The Tamil Nadu State Variety Release Committee has released ADT41 (5592) for general cultivation during kharif (monsoon) season in Tamil Nadu.

Mahsuri derivatives Assam. They were developed by

Bahadur, and Ranjit varieties are free of some of the undesir- developed: Kushal, Maniram, crossing Pankaj and Mahsuri. The

able traits of Mahsuri. They are ferti- T. Ahmed, D. K. Baruah, K. K. Sarmah, P. K. Pathak, H. C. Bhattacharyya, S. Ali,

lizer-responsive and moderately

and A. K. Pathak, Regional Agricultural resistant to shattering. Kushal, Maniram,

Research Station, (RARS) Assam Agricul- and Bahadur are resistant to blast. tural University, Titabar 785630, India Important characteristics and yield data

are presented in Tables 1 and 2. Kushal, Maniram, Bahadur, and Ranjit have been recommended for flood-free rainfed lowlands during winter season in

Table 1. ADT4l (JJ92) yields in Tamil Nadu, India. Table 1. Main characteristics of varieties.

Type of trial and year

TNRRI, Aduthurai, 1990-92 Multilocation trial, 1991 Demonstration, at research

stations, 1992 On-farm trial, 1992 Adaptive research trial, 1992

Total/mean

Av Trials grain (no.) yield

(t/ha)

4 3.9 4 3.0 8 3.7

8 4.6 20 5.8 44 4.2

Character

Height (cm) Duration (d) Panicle length (cm) 1,000-grain wt (g) Hulling (%) Milling (%) Head rice (%) Amylose content (%) Grain length (mm) L-B ratio

Kushal

116 150

25.8 23.1 78.0 72.0 63.0 22.67

5.8 3.4

Maniram

105 150

26.5 21.6 79.5 73.0 62.0 20.12

5.6 3.3

Bahadur

114 155

27.7 20.2 79.0 71.0 64.0 22.71

5.5 3.6

Ranjit

99 155

27.5 17.4 79.5 68.0 57.0 22.99

5.4 3.5


Integrated germplasm improvement—irrigated

– – –

Table 2. Yield data of the Mahsuri-derived varieties under multilocational testing. Assam, India, 1989-91.

Yield (t/ha) Variety

Titabar a North Lakhimpur a Pambari b Tinsukia b Kalachand b Mahakal b North Lakhimpur b Nowgaon b

Kushal 5.8 4.3 5.8 3.6 6.1 4.5 2.5 5.5 6.3 Maniram 4.2 4.4 5.4 3.6 5.5 4.9 3.1 4.7 6.0 Bahadur 4.2 4.5 3.3 6.1 4.5 3.3 6.5 5.3 Ranjit 4.2 5.3 3.2 4.2 4.4 3.9 5.8 6.1 Mahsuri 3.2 4.2 4.0 2.5 2.3 4.0 4.0

–

(check)

a RARS. b Field trial station. All tests were conducted in 1991 except those in Titabar, which were in 1989 and 1990.

On-farm evaluation of rice Table 1. Mean grain yield and other agronomic characters a of 6 early rice cultivars grown in 7 farmers' fields. Chitwan, Nepal, Mar-Jul 1992. cultivars for spring season in

the lower hills of Chitwan, Nepal

Productive Nonproductive Grains/ Days to Days to Grain Cultivar tillers/m 2 tillers/m 2 panicle heading maturity yield

(no.) (no.) (no.) (no.) (no.) (t/ha)

J. Timsina, F. P. Neupane, G. K. Shrestha, B. B. S. Dongol, R. C. Sharma, N. P. Joshi,

Chaite-2

and N. K. Mishra, Institute of Agriculture Chaite-4 Ghaiya-2

and Animal Sciences, Rampur, Chitwan, Radha-2 Nepal Radha-32

Most farmers in the village of Kholaghari CV (%) Farmers' variety b

75 ab 7 ab 115 a 66 a 97 a 4.8 ab 73 ab 11 a 95 b 58 c 88 c 4.2 bc 74 ab 8 ab 106 ab 62 b 93 b 5.2 a 58 b 6 b 95 b 53 d 84 d 4.2 bc 75 ab 7 ab 106 ab 63 b 97 a 4.1 bc 84 a 8 ab 112 a 56 ab 98 a 3.9 c 21.2 48.2 13.1 3.6 2.9 15.7

and a few in the village of Daletar in Chitwan, Nepal, have farmer-managed irrigation systems and can grow irrigated transplanted rice in the spring before the main season rice crop. Many farmers, however, keep their lands fallow or grow maize in the spring because suitable rice cultivars are not available and they are unsure whether an early rice could be grown successfully.

We evaluated six promising rice cultivars in irrigated bunded terraces of seven farmers' fields (six in Kholaghari and one in Daletar) from Mar to Jul 1992. Soil was sandy loam or loam, with 5.1-7.6 N, 0.03-0.06 kg available P/ha, and 10-58 kg available k/ha. Each farmer's field served as one replication; plots were 60 m 2 . Two to three seedlings/ hill were transplanted at the spacing used by the farmers. Fertilizers were applied at 60:8.8:16.6 kg NPK/ha. Half of the N and all of the P and K were applied as basal; the remaining N was topdressed at the grain-filling stage. The participant farmers completely managed the trials.

We found significant differences among rice cultivars for most characters. Chaite-2 and Ghaiya-2 yielded the most among cultivars (Table 1).

to evaluate the trials after harvest. A matrix ranking was done on cultivar

We requested the farmers to assemble

a ln a column, means followed by the same letter are not significantly different at the 5% level by DMRT. b Differed among farmers. Two used Laxmi, while the others used CH45.

Table 2. Matrix ranking of early rice cultivars grown by participant farmers, Chitwan, Nepal, Mar-Jul 1992.

Varieties

Chaite-2 Chaite-4 Ghaiya-2 Radha-2 Radha-32 Laxmi Attribute

Yield Grain 7 3 5 3 4 8 Straw 6 3 3 8 4 6

Tillering 7 4 5 3 4 7 Disease resistance 7 4 5 3 4 8 Insect resistance 7 3 5 3 4 8 Early maturity 4 6 5 7 4 4 Shattering 6 4 5 4 5 6 Threshing ease 4 6 5 7 4 4 Dormancy 7 3 5 4 4 7 Milling recovery 5 4 5 5 6 5

6 Grain weight 4 4 6 3 7 Cooking quality 6 5 5 4 4 6 Best variety: Two farmers - Laxmi

Rest of the farmers - Chaite-2

attributes. Farmers were given 30 maize cultivars they would plant next year, all of kernels and asked to allot them to show them chose Chaite-2 and Laxmi. The the relative differences among the participant farmers reported that many cultivars for a particular attribute. After other farmers visited their trials and asked discussion, farmers agreed on how the for seeds of Laxmi and Chaite-2. We maize kernels should be allotted. The concluded that local farmers preferred same procedure was used for all attributes. these two cultivars.

When asked which cultivar they would Farmers considered Chaite-2 and Laxmi choose if they could only use one, two superior to the other cultivars, although we farmers chose Laxmi, while the rest chose thought Chaite-2 and Ghaiya-2 were the Chaite-2 (Table 2). When asked which outstanding cultivars.


– – –

IR36-derived lines are stable Table 2. Parentage and agronomic attributes of promising rice genotypes from Pattambi, India. high yielders in Kerala, India Mean Productive C. A. Rosamma, C. R. Elsy, and P. V. Genotype Parentage Duration plant height tillers

Prabhakaran, Regional Agricultural Research (d) (cm) (no.) Station, Pattambi, Kerala 679306, India KAU8753 IR36/Jyothi 115 85 5.8

IR36 was used in a rice breeding program at Pattambi to develop varieties with multiple resistance to pests and high adaptability. Six short-duration, semidwarf lines evolving from this program were evaluated with IR36 and popular high-yielding variety Jyothi for grain yield and other agronomic attributes.

Experiments were laid out in a randomized block design with three replications. Tests were conducted in different seasons including 1987, 1988, and 1989 kharif (monsoon): 1989 and 199 I summer; and 1990 rabi (wet). Plots were 10 m 2 and spacing was 15 × 10 cm. Recommended agronomic and plant protection measures were followed. Grain yields were recorded at 14% moisture level. Stability of the genotypes over six environments was analyzed.

Regression of genotypes for average yield on the environmental index resulted in regression coefficients (bi) from 0.88 to 1.34. Deviation from regression mean squares (s 2 d) ranged from -0.05 to 0.21 (Table 1). These stability parameters were not significant, indicating that all lines tested were stable yielders across the environments.

Rice cultures KAU8754 and KAU8755 had bi very close to unity (1.04), which indicates their highly stable performance across environments tested. These two cultures and KAU8753 and KAU87.56 had grain yields higher than

Table 1. Mean grain yield (t/ha) and estimates of stability parameters for 8 rice genotypes over 6 environments.

~

KAU8754 IR36/Jyothi KAU8755 IR36/Pavizham KAU8756 IR36/Pavizham KAU8757 IR36/Cul 23332-2 KAU8759 IR36/Annapoorna IR36 (check) Jyothi (check)

the pooled mean. KAU8756 yielded the most at 4.4 t/ha and had the highest bi (1.34), indicating this genotype’s superior performance under favorable environments. (See Table 2 for parentage and agronomic attributes of genotypes.)

with IR36 were stable yielders in kharif, All six genotypes derived from crosses

Wei You 647: a new high- yielding hybrid rice Mao Chang-Xiang and Deng Xiao-Lin, Hunan Hybrid Rice Research Center, 41 01 25 Changsha, China

Indica/japonica hybrid rice could have stronger heterosis than indica/indica hybrids, but poor seed set is a major problem. By hybridizing an indica restorer line with a japonica variety and backcrossing, an indica-type restorer line (647 R) with japonica characteristics has been developed. Hybrids of 647 R and

115 115 110 115 100 115 115

90 88 90 87 80 90 90

5.5 3.9 6.5 5.0 5.1 5.5 3.9

rabi, and summer seasons. KAU8753,

recommended for use in breeding programs aiming to develop cultivars with high yield potential and adaptability. KAU8754 was released recently in Kerala as Kairali (Ptb 49). and KAU8756 as Kanchana (Ptb 50).

KAU8754, KAU8755, and KAU8756 are

indica cytoplasmic male sterile lines V20 A and Zhen Shan 97 A have shown very strong heterosis and high yield ability.

Hybrid Wei You 647 is the F 1 progeny of V20 A/647 R. It was ranked first five times and second twice in various yield trials and recorded a 4.3-13.7% increase in yield over commercial hybrid checks. (See table for yield results in the 1991 China National Hybrid Rice Yield Trial.)

Yield potential of Wei You 647 is high and stable in on-farm cultivation. Wei You 647 has been released for commercial production.

Yield performance of top 4 new hybrid rices in the China National Hybrid Rice Yield Trial over 21 locations. China, 1991.

Hybrid Growth Yield Yield over duration (t/ha) that of check Rank

(d) (%)

Wei You 647 133 7.6 13.7 1 (V20 A/647 R)

Genotype x bi s 2 d Shan You 20964 (97 A/20964 R)

MU8753 4.1 0.93 –0.05 KAU8754 4.1 1.04 KAU8755 4.1 1.04 0.04

KAU8757 3.7 0.89 MU8756 4.4 1.34 0.21

(V20 A/77 R)

0.03 Shan You 3-9

KAU8759 3.9 1.13 0.04 (97 A/3-9 R)

0.15 Wei You 77

130

127

131

IR36 3.7 0.91 Jyothi 3.5 0.88 Wei You 64 127

AV 3.9 (V20 A/IR9761-19-1 R) (check)

7.4 10.3

7.1

7.1

6.7

7.0

7.0

–

2

3

4

5


0.05 0.07

KSB54, derived from cross IR18189-2-3/ IR36, was released in Mar 1992 for use in the Mekong Delta area.

It is 85-95 cm tall and has a 105-110 d growth duration. It has long slender grain, good cooking quality, and a 1,000- grain weight of 26 g. It is drought- and sulfate acid soil-tolerant.

KSB54 is moderately resistant to the Mekong Delta BPH population, although neither of its parents are resistant (Table 1). In a BPH field survey, KSB54 scored and performed about the same as moderately resistant IR64 and as good as popular varieties IR66 and IR13240-108- 2-3 or better (Table 2).

Mean grain yield was 5.6 t/ha across five successive trials at IAS in 1989-91 and 4.9 t/ha in IAS multisite trials in 1990, compared with 4.8 and 5.0 t/ha, respectively, for check IR13240-108-2-3.

KSB.54 is planted on about 15,000 ha in the Mekong Delta.

Duong Thanh Tai and Pham Van Bien, lnstitute of Agricultural Science (IAS), Ho Chi Minh City, Vietnam

KSB54, a new variety with moderate resistance to Mekong Delta population of brown planthopper (BPH) (Nilaparvata lugens Stål)

Table 1. Reaction of KSB54 and its parents to BPH.

Variety Reaction to BPH a

Biotype 2 Biotype 3 Mekong Delta population

KSB54 R R MR lR18189-2-3 IR36

R R

S R

S S

a R = resistant, MR = moderately resistant, and S = susceptible.

Table 2. Performance of KSB54 and other varieties in BPH field nursery in Tien Giang, Vietnam, 1991 wet season.

Days after transplanting

Zhenong 8010: a new indica rice variety with high yield, blast (BI) resistance, and good quality Shi Chunhai, DU Ruwej, Lin Dawej, Zhang Wanggen, Xu Yunbi, He Zhuhua, and Shen Zongtan, Agronomy Department, Zhejtang Agricultural University, Hangzhou 31 0029, China

Table 1. Yield potential of Zhenong 8010 in China, 1992.

Yield Increase Site (t/ha) over check a

(%)

Hangzhou, Zhejiang 7.6 4.4 Ningbo, Zhejiang 7.7 0.1 Yuhuan, Zhejiang 8.5 11.4 Yiyang, Hunan 7.1 22.1 Changting, Fujian 7.7 22.5 Ganzhou, Jiangxi 6.4 21.6

a Guangluai 4.

Variety 65 70 75

BPH/hill Score a BPH/hill Score BPH/hill Score (no.) (no.) (no.)

KSB54 554 5.0 179 5.6 21 5.6 IR66 380 5.0 112 8.3 10 8.3 MTL 61 276 7.6 24 8.3 1 9.0

IR64 567 3.0 237 4.3 33 5.0 TN1 (susceptible check) 419 9.0 33 9.0 1 9.0

lR13240-108-2-3 482 5.0 157 7.0 20 7.6

lR50404-57-2-2-3 342 4.3 147 4.3 18 4.3

a Scored using Standard evaluation system for rice scale of 0-9.

Zhenong 8010 is a new semidwarf indica compared with check Guangluai 4, which rice variety derived from the indica × scored 5.7 and 6.8, respectively. japonica cross of Keqing 3/IR29/8004. Morphoagronomic characters are in Zhenong 8010 is suitable for both Table 2. Appearance, hulling recovery, seasons in the double-cropped area of milling recovery, gel consistency, protein southern China. It was released in Jan content, and cooking and eating quality 1993 as an early rice variety. About meet China's national index for good- 7,000 ha in southern China are planted to quality rice. Grain length is 6.8 mm with Zhenong 8010, which has a growth a 3.0 length-breadth ratio. Grain is duration of about 116 d. semitranslucent with 14.4% protein

Zhenong 8010 has high, stable yield content, 8.4% amylose, low gel consist- potential under normal fertilization. It ency (97 mm), and high gelatinization yielded 6.4-8.5 t/ha in regional trials in temperature (alkali spreading value of 3). 1992 (Table 1), which was 0.1-22.5% Hulling recovery is 80.8%: milling more than the check. Its leaf B1 and neck recovery, 72.7%; and head rice recovery, B1 resistance scores were 1.7 and 0.8, 45.5%.

Table 2. Morphoagronomic characters of Zhenong 8010 at different sites in China, 1992.

Character Hangzhou, Zhejiang

Site

Taojiang, Changting, Fenyi , Hunan Fujian Jiangxi

Plant height (cm) 79.5 79.8 83.0 89.0 Panicle length (cm) 17.9 20.9 18.5 19.0 Grains (no./panicle) 78.8 112.3 88.5 93.7 Fertility (%) 87.5 63.8 90.3 70.5 1,000-grain wt (g) 23.2 22.5 24.5 23.0


Bogabordhan: a stable, high- yielding, low-input traditional variety of Assam, India U. C. Kalita, Plant Breeding and Genetics Department (PBGD), Assam Agricultural University (AAU), Jorhat; D. K. Baruah, Regional Agricultural Research Station (RARS), Titabar; and L. P. Upadhaya, PBGD, AAU, Jorhat, Assam, India

Northeastern India is endowed with many landraces of rice that are adapted specifically to the harsh, varying rainfed environments of the region. These varieties are the results of selections made by farmers. Farmers prefer varieties that have reason- ably high levels of relative productivity and stability under management situations with little or no inputs.

We evaluated the performance of 20 local varieties selected from sali (wet season [WS]) germplasm stock maintained at the RARS, based on their phenotypic acceptability for three con- secutive wet seasons from 1988 to 1990. Their performance was compared with two widely grown checks, Manoharsali and Jaya.

The crop was transplanted under rainfed lowland conditions at 20- × 20-cm spacing. The experiment was laid out in a randomized block design with 7.2-m 2

plots and three replications. No fertilizers or pesticides were applied. The experimental site had 587.4 kg available N/ha, 19.5 kg available P/ha, and 86.3 kg available K/ha.

Bogabordhan and Manoharsali were

varieties. Bogabordhan yielded 45.2% photoperiod-insensitive (see table). and lower yield (3.4 t/ha) than other photoperiod-sensitive and Jaya was low percentage of filled spikelets (71%)

grain yield, filled spikelet percentage, and The lack of significance of the 1,000-grain weight. regression of yield across years indicates

The variety had adequate field that Bogabordhan has the stability resistance to sheath rot and moderate needed by resource-poor farmers. resistance to bacterial blight, sheath Bogabordhan’s high yield of 4.5 t/ha blight, and false smut. Higher disease coupled with it stability make it popular incidence in Jaya could be a reason for its among farmers in Assam.

Bogabordhan outyielded both checks in more than Jaya (see table).

Performance of Bogabordhan and checks at Titabar, Assam, India, 1988-90 WS.

Checks Character Bogabordhan

Manoharsali (local)

Jaya

Photoperiod sensitivity Sensitive Plant height (cm) 141

Sensitive Insensitive 139 99

Days to maturity (d) 145 149 131 Panicles/m 2 (no.) 224 231 236 Lodging incidence a 1 9 3 Culm strength b 3 9

27 1

Panicle length (cm) 25 23 Spikelets/panicle (no.) 114 123 146 Filled spikelets (%) 96 91 71 1,000-grain wt (g) 29.9 25.6 24.3 Brown rice length (mm) 5.73 6.06 Brown rice width (mm) Disease reaction c

Bacterial blight 3 5 Sheath rot

7 1

Sheath blight 3 5

3 0 5 False smut 3 3 7

Grain yield (t/ha) 4.9 4.8 3.4 Regression coefficient

Mean square deviations (s 2 d) 0.25 ns 0.14 ns 0.20 ns

Increase in yield (%) in Bogabordhan over 1.2 45.2

5.93 2.93 2.53 2.19

(b) of yield on years d 0.022 ns 3.467* –1.355*

a 1 = less than 20% area lodged, 3 = 20.40%. 9 = more than 80%. b 1 = strong, 3 = moderately strong, 9 = very weak. c 0 = highly resistant, 1 = resistant, 3 = moderately resistant, 5 = moderately susceptible, 7 = susceptible. d ns = not significant, * = significant at the 5% level.

Upland rice varieties Sita and Upland rice is grown on only 2.5% Rimke released to farmers in (about 36,000 ha) of the area under rice

in Cambodia. Most of these upland areas are in the provinces of Kampong Cham, Cambodia

R. C. Chaudhary, Cambodia-IRRI Rice Siem Reap, Kampong Thom, Mondul Project. P. O. Box 1, Phnom Penh, Cambo- Kiri, Ratana Kiri, Kandal, Kampong dia; O. Makara,P. K. Hel, and S. Sophol, Agronomy Department, Phnom Penh, Cambodia

Speu, and Stung Treng. Because there are no recognized

varieties for these rainfed uplands, we conducted a speedy varietal identifica- tion project using some research stations

and many farmers’ fields. The trial was conducted during 1989 at four locations in Kandal, Kampong Speu, and Phnom Penh. During 1990 and 1991, we distributed many trial sets for on-farm testing. (See Table 1 for performance of the varieties.)

ITA150 is derived from the cross 63-83/(RO1, SE363G, Dourado Precoce) where the male parent was a mixture of pollen from three varieties. The breeding line was advanced with the pedigree TOX502-41-1-1. ITA257 is


Integrated germplasm improvement—rainfed lowland

Integrated germplasm improvement—upland

–

Table 1. Yield (t/ha) of Sita and Rimke in some provinces of Cambodia, 1989 and 1990.

Province (Location) Sita Rimke Check

Phnom Penh (Chumcar Daung) 2.7 3.7 4.3 Kampong Speu (Chhbar Morn) 1.1 0.9 1.0 Kampong Speu (Phking) 1.0 0.8 0.8 Kandal (Udong) 1.1 1.3 1.6

Table 2. Morphoagronomic characteristics of Sita and Rimke compared with check variety C22.

Characteristic Sita Rimke C22

Plant height (cm) 91 93 113 Duration (d) 91 103 135 Culm diameter (mm) 4.4 4.2 4.5 Root diameter (mm) 1.37 1.35 1.29 Panicle length (cm) 23.0 22.8 22.9 Tillers/plant (no.) 8 8 11 Leaf length (cm) 40.3 39.9 29.2 Leaf width (cm) 1.2 1.2 0.9 Flag leaf area (cm 2 ) 32.8 32.2 16.9 Panicle weight (g) 2.89 3.29 2.30 100-grain wt (g) 3.25 3.96 2.42 Grain length (mm) 7.0 7.0 6.00 Grain width (mm) 2.3 2.3 2.5 Grain type a LS LS LB Harvest index 0.51 0.49 0.43

a S = long slender; LB = long bold.

derived from cross IRAT 13/Dourado Precoce//TOX490-1. ITA150 and ITA257 have been released as varieties in Africa and were introduced to Cambodia from the International Institute of Tropical Agriculture, Nigeria. Morphological characteristics of these varieties are in Table 2.

More than 100 Cambodians partici- pating in a cooking quality test rated the grain quality characteristics of Sita and Rimke to be superior to that of IR64, IR72, Kru, and IR66.

ITA 150 and ITA257 were released for cultivation by Cambodian farmers as Rimke and Sita, respectively. Both varieties are early maturing, have drought tolerance and blast resistance, and possess excellent grain quality. The varieties are spreading among farmers although no organized seed multiplica- tion and extension systems exist.

Vandana (RR167-982), a new Table 1. Characteristic features of Vandana and popular local variety Brown gora.

upland variety in the plateau region of Bihar, India

Character Vandana Brown gora

P. K. Sinha, C. V. Singh, M. Variar. V. S. Chauhan, and K. Prasad. Central Rainfed Upland Rice Research Station (CRURRS), P. O. Box 48, Hazaribag 825301, Bihar, India

Plant height (cm) Duration (d) Vigor

Early Late

About 5.1 million of India’s 6.5 million ha of upland rice is concentrated in eastern India. Many upland farmers grow gora rice varieties, which have average yields of less than 1 t/ha.

RR167-982, derived from the cross C22/Kalakeri, was released as Vandana in 1992 by the Bihar State Variety Release Committee. It is for cultivation in the uplands of Chhotanagpur Plateau, which make up 33% of Bihar’s upland area.

Vandana is semitall (115-130 cm) and has very good early and late vigor that allows proper stand establishment and competition with weeds (Table 1). It has a growth duration of 90-95 d and long roots (100 cm). Vandana’s panicles are compact and exsert fully; 1,000-grain weight is 24.2 g. Vandana has white kernels that are long and bold and of

Tillering (no.) Panicle length (cm) Panicle weight (g) Lodging

Spikelets/panicle (no.) 1,000-grain wt (g) Grain yield (t/ha) Grain color Kernel color Kernel length (mm) Kernel breadth (mm) L-B ratio Grain type Abdominal white Water uptake (ml) Cooked kernel length (mm) Amylose content (%) Isozyme group a

Drought reaction

a Using Glaszmann's 1-6 scale.

115-130 90-95

Very good Excellent

3.03 20.12

2.50 Moderate Moderately resistant 76 24.2

Straw White

6.0 2.3 2.53

Long, bold Present occasionally 285

2.5-3.5

9.8 19.1

0

110.9 85-90

Excellent Excellent

3.77 18.87

1.49 High Resistant

41 28.5

Brown Red

5.6 2.7 2.07

Short bold Present 320

9.6 22.0

1

1.0-2.0


Table 2. Yield data from multilocation evaluation of RR167-982 (Vandana) compared with local and improved checks. Bihar and Orissa, India, 1988-91.

Site Vandana Kalinga Ill Birsadhan 101 Brown gora (local check)

Hazaribag district, Bihar Vigyan Kendra, Pondicherty 4.2 1.5 0.7 1.6 CRURRS 2.4 1.5 1.1 1.8 Barkatta 3.4 1.8 Handio 2.3 1.5 1.2

Mean 3.2 1.6 0.9 1.5 Giridih district, Bihar

Location 1 2.6 2.6 2.1 Location 2 1.9 1.9 1.2 1.1 Location 3 3.2 3.0 2.8 Location 4 4.7 3.6 4.2 Location 5 4.3 3.0 3.0

Mean 4.2 3.5 3.3 1.1

Kalahandi district, Orissa Location 1 2.9 2.6 2.7 2.5 Location 2 3.4 3.3 3.2 1.6

Mean 3.2 3.0 3.0 2.1

acceptable cooking and eating quality. It is moderately resistant to blast (Bl) in uniform B1 nurseries and to brown spot under field conditions. It is also resistant to sheath rot.

Vandana was evaluated under direct- seeded conditions in a station trial, multilocational testing, and in farmers' fields (Table 2) during 1988-91. It outyielded Brown gora, Birsadhan 101, and Kalinga III in grain and straw production. It averages 2.5-3.5 t/ha under normal conditions, although up to 4.7 t/ha have been recorded in farmers' fields. Vandana has also performed equally well in the highly drought-prone Kalahandi district of Orissa.

Performance of some promising deepwater rice (DWR) cultivars in northwestern Nigeria W. N. Umeh, National Cereals Research lnstitute (NCRI), Badeggi, PMB 8, Bida, Niger State, Nigeria

Seven lines of Oryza sativa and three lines of O. glaberrima were tested for flood tolerance and yield performance under rainfed deepwater condition at NCRI, Birnin Kebbi. Lines were evaluated against check FARO 14, which is a long-duration (170-198 d), photoperiod- sensitive variety.

The experiment was laid out in a randomized complete block design with four replications. The gross plot was 4 × 3 m, and the net plot, 3.2 × 2.2 m. Two seeds per hill were sown on 17 Jun 1991 at a spacing of 20 × 20 cm.

A basal application of 30 kg NPK/ha was made at planting. Three weeks after seedling emergence, another 30 kg N/ha as urea was placed deeply among four hills before the floodwaters started in mid-July. Flood depth was recorded weekly from 16 Jul to 19 Nov. The maximum depth measured was 1.4 m on

Growth attributes and grain yield of deepwater rice cultivars. a NCRI, Birnin Kebbi, Nigeria, 1989-91.

Floodwater

Cultivar 50% height Panicles/m 2 Grain yield (t/ha) weekly basis

1989 1990 1991 Date cm

Days to Plant depth on

flowering (cm) (no.)

(1991)

O. glaberrima b

Jan-iri 99 161 3 89 2.2 3.0 2.4 16 Jul 7 Farin-iri 107 186 385 4.1 3.5 3.6 23 Jul 13 Yar-kaushe 101 181 388 3.0 3.3 3.3 30 Jul 18 O. sativa 6 Aug 25 DM17 120 213 338 5.3 5.0 5.4 13 Aug 30 DA29 109 198 371 5.6 5.0 3.7 20 Aug 47 Maiada 109 201 361 5.4 5.5 5.4 27 Aug 53 BKN6986-17 113 190 316 4.3 5.6 2.7 3 Sep 68 FARO 4 (KAV-12) 119 200 416 2.4 3.2 3.4 10 Sep 83

17 Sep 100 FARO 6 (ICB) 115 220 358 3.6 2.4 4.9 24 Sep 121 FARO 7 (Maliong) 129 209 379 3.5 4.7 5.1 30 Sep 133

10 Oct 140 FARO 14 (FRRS-43-111-2) 141 233 351 3.0 4.1 6.0 17 Oct 125

CV (%) 4.7 10.9 20.1 22 Oct 89 LSD (0.01) 18.1 ns c 1.63 29 Oct 75

5 Nov 60 12 Nov 54 19 Nov 43

a Results reported are 1991 data unless otherwise noted. b lndigenous types of rice. c ns = not significant.


Inetgrated germplasm improvement—deepwater

– –

–

–

– – –

3-7 Oct. Harvesting began on 23 Oct and ended on 25 Nov.

All entries had submergence tolerance and elongation ability. Plant height, which reflects elongation ability in relation to water depth, was significantly different among entries (see table).

Tillers and panicles/m 2 were quite numerous, but entries did not significantly differ. Glaberrima cultivars had a high incidence of grain shattering,

which might be a major factor in their low grain yield.

Yields did not significantly differ among entries. None of the test entries outyielded FARO 14. This contrasts the previous year's results when DM17, DA29, and Maiada outyielded FARO 14 by producing more than 5 t/ha.

O. glaberrima mature 3-5 wk earlier than FARO 14. The earliness of DA29 and

Cultivars DA29, Maiada, and

Maiada makes them suitable for deepwater areas where flood duration is short and the harmattan cold and wind makes cultivating long-duration varieties risky.

Their acceptability, based on pheno- type and grain quality as determined with the Standard evaluation system for rice, is excellent.

Netravathi (KKP-6): a promising rice variety for coastal lowlands of Karnataka, India N. A. Janardhana Gowda, N. S. Parameswar, 6. Vidyachandra, and

Table 1. Performance of Netravathi (KKP-6) in yield trials, a Karnataka, India, 1983-87.

Replications Plot size Grain yield (t/ha) Trial Year Location (no.) (m 2 )

KKP-6 Phalguna

GM-resistant 1983 Agricultural Research 3 1.5 × 3.0 4.9 3.2 varietal trial Station, Mangalore

C. Malleshappa, University of Agricultural Sciences, Agricultural Research Station, Kankanady, Mangalore, Karnataka, India.

GM-resistant 1984 Agricultural Research 4 4.6 × 2.0 4.4 3.5 varietal trial Station, Mangalore

Rice is grown on more than 150,000 ha in coastal Karnataka during kharif (monsoon) season. Phalguna, the variety commonly grown in lowlands that are partially submerged during heavy rains, has problems with spikelet sterility and is susceptible to neck blast (BI).

IET2886 was crossed with Red Annapurna, and KKP-6 was identified and released as Netravathi in 1990. Netravathi outyielded Phalguna (Table I) in multilocation trials conducted at Mangalore and Brahmavar. Leaf and neck B1 incidence was less in Netravathi than in Phalguna. Netravathi also resists gall midge (GM) (Table 2). It has a

GM-resistant 1985 Regional Research 4 6.2 × 1.8 4.3 4.4 varietal trial Station, Brahmavar

Rice varietal 1987 Regional Research 3 4.5 × 2.0 4.7 3.6 trial Station, Brahmavar a Fertilized at the rate of 75-75-90 kg NPK/ha.

growth duration of about 135- 140 d and Table 2. Reaction of Netravathi (KKP-6) to BI is 104 cm tall. It can withstand submer- and GM in coastal Karnataka, India. a

gence for 5-7 d.

grain than does Phalguna. Netravathi has (% affected) (% affected) less spikelet sterility than Phalguna, and it is suitable for parboiling. The variety is Netravathi 1.3 5.1 0.00

recommended for lowland areas during Phalguna 3.4 24.5 0.75

kharif. a Mean of four trials.

Netravathi yields about 11 % more Variety BI BI (% affected) Leaf Neck GM


Integrated germplasm improvement-tidal wetlands

Crop and resource management Table 1. NRase activity (µ moles NO 2 /gfresh weight per h) at different growth stages of varieties and hybrids with different growth durations. Coimbatore, India, 1990 WS.

Variety or hybrid Duration (d) 15 DAS 30 DAS 50 DAS 70 DAS 90 DAS

IR50 105 1.58 3.12 6.85 8.97 8.43 Co 37 120 1.26 2.77 6.52 8.63 ADT36

9.14 114 1.39 2.93 6.66 8.75 8.76 110 1.43 2.96 6.69 8.81 8.72

co 39 95 1.80 3.34 7.06 9.18 ASD8

5.23 87 1.94 3.45 7.21 9.33 5.94

Nitrate reductase (NRase) activity as an index for early maturity

ASD16

S. Manonmani, T. B. Ranganathan, S. R. Sree Rangasamy, P. Narasimman, and M. Suresh, Centre for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore 641003, India

Studying parents and hybrids increases understanding of the nature of the gene action involved in the expression of NRase activity and earliness. NRase is the enzyme involved in converting nitrite to nitrate. We estimated NRase at five stages in four early (IR50, Co 37, ADT37, and ASD 16) and five very early rice varieties (ASD8, ASD17, Co 39, Heera, and Kalyani 11) and their 20 (5 × 4) hybrids (Table 1).

leaf samples following the method of Nicholas et al (1976) at 15, 30, 50, 70,

NRase analysis was carried out using

ASD17 95 Heera 87 Kalyani II 86

Mean of parents 99.89 CV (%)

IR50/Co 39 94 IR50/ASD8 105 IR50/ASD17 97 IR50/Heera 102 IR50/Kalyani II 95

Co 37/Co 39 112 Co 37/ASD8 111 Co 37/ASD17 103 Co 37/Heera 105 Co 37/Kalyani II 94

ADT36/Co 39 95 ADT36/ASD8 105 ADT36/ASD17 101 ADT36/Heera 102 ADT36/Kalyani II 95

ASD16/Co 39 95 ASD16/ASDS 95

1.79 1.96 1.99 1.68

16.30

1.82 1.57 1.75 1.65 1.80

1.41 1.49 1.63 1.59 1.79

1.77 1.79 1.67 1.66 1.80

1.80 1.77

3.32 3.48 3.52 3.21 8.52

3.36 3.11 3.28 3.18 3.33

2.94 3.02 3.02 3.13 3.33

3.30 3.32 3.20 3.19 3.33

3.32 3.30

7.06 7.23 7.26 6.95 3.98

7.08 6.81 7.01 6.51 7.07

6.67 6.75 6.89 6.86 7.06

7.05 7.05 6.53 6.93 7.06

7.07 7.03

9.18 5.81 9.34 5.93 9.38 5.52 9.05 7.05 3.11 23.33

9.26 5.97 8.94 8.65 9.13 7.47 9.03 8.25 9.18 5.77

8.79 8.76 8.87 8.73 8.99 8.27 8.98 8.35 9.18 5.75

9.16 7.22 9.15 8.33 8.56 8.22 9.04 8.26 9.18 5.78

9.18 5.77 9.16 7.44

and 90 d after sowing (DAS). The

ASD16/Kalyani Il 94 experiment was laid out in randomized

ASD16/ASD17 100 1.69 3.22 6.95 9.06 7.49

block design, with three replications, and

ASD16/Heera 106 1.51 3.06 6.76 8.91 8.63 1.82 3.35 7.08 9.56 8.65

Mean of F 1 s 100.30 1.69 3.21 6.91 9.08 7.44 conducted at Coimbatore in 1990 wet CV (%) 7.10 4.04 2.66 2.47 16.06 season (WS) under irrigated condition.

Growth duration of early parents was

105-120 d and 86-95 d for the very early Table 2. Correlation coefficient between total growth duration and NRase activity at different growth stages. Coimbatore, India, 1990 WS. a

parents. NRase activity increased from seedling to flowering stage (up to 70 DAS) and declined thereafter. NRase increased in late-maturing parent Co 37, but at a rate less than that of early- maturing parents (Table 1). Among the hybrids, ASD16/Kalyani II and IR50/ Co 39 recorded very high NRase activity from seedling to flowering stage. Both had durations of 94 d.

All the hybrids were significantly early compared with mean duration of the parents. Most of the hybrids with very early parents Co 39 and Kalyani II matured early. Kalyani II hybrids were the earliest of the F 1 s.

15 DAS 30 DAS 50 DAS 70 DAS 90 DAS

Total growth 15 DAS 30 DAS 50 DAS 70 DAS

duration –0.97** –0.96** –0.85** –0.84** 0.87** 0.99** 0.87** 0.86** –0.84**

0.86** 0.85** –0.85** 0.89** –0.81**

–0.81** 90 DAS a * * = significant at the 1% level.

Growth duration of the parents and hybrids and NRase activity at 15 DAS showed a significant negative correlation (–0.97** to –0.84**), except for NRase and 90 DAS, which showed a significant positive value (0.87**) (Table 2).

The intercorrelation of NRase activity at different DAS showed significant positive values. Estimating NRase activity seems to be a useful measure for selecting the early-maturing types at an earlier stage of crop growth.


Physiology and plant nutrition

–

–

Urea was the most efficient of the N sources. Efficiency of Gliricidia N and Sesbania N was about 67% and 45%,

Comparative efficiency of Sesbania, Gliricidia, and urea as N sources in wetland rice D. K. Kundu, K. V. Rao, and K. G. Pillai, Directorate of Rice Research (DRR), Ralendranagar, Hyderabad 500030, Andhra Pradesh, India

Seshania cannabina is a well-recognized green manure (GM) for rice. Farmers have not widely adopted it because they are reluctant to use their land, water, and other inputs for raising a crop exclu- sively for GM. Gliricidia sepium, a perennial leguminous tree, is grown extensively in roadsides, hedges, and field boundaries in the tropics. High foliage yields, vigorous coppicing ability, and tolerance for regular lopping make Gliricidia a good GM. Using loppings for GM is popular in many parts of southern India.

We compared efficiency of Sesbania. Gliricidia, and urea as N sources for rice variety Rasi in a Vertisol with 0.92% organic C, 0.10% total N, and pH 7.9 during 1988 dry season (DS).

The equivalent of 100 kg N/ha from each source was supplied to rice crops. A no-N control was also used. Eight-wk-

respectively, that of urea N. Crop N old Seshania plants (from a different

higher than from Sesbania at both PI and field) and 1-m-long tender Gliricidia uptake from Gliricidia was significantly

Gliricidia seems to be more promising transplanting (WAT). Rice grain yield than that from Sesbania (see table). monitored through the first 8 wk after stage (4 WAT) was significiantly higher soil under the different N treatments was crop from Gliricidia at early tillering stage. The 2 M KC1 extractable NH4-N in Sesbania. Availability of N to the rice ing and 57 d later at panicle initiation (PI) was 16.6 kg/ha and 13.9 kg/ha with applied in two equal splits at transplant- 15 cm plow layer) treated with Gliricidia Gliricidia, 0.64% total N. Urea was mean available N content in the soil (0- samples contained 0.50% total N, and the

While the rice crop was growing, ing. On a fresh weight basis, the Sesbania the soil than Sesbania through 8 WAT. single basal dose at 2 d before transplant- Gliricidia released relatively more N to incorporation into the puddled field as a 0.6 t/ha more than with Sesbania. chopped into 10-15 cm pieces for maturity. Rice yield using Gliricidia was loppings (collected from hedges) were

and total N uptake at PI and at maturity than Sesbania as a GM source of N for were evaluated. wetland rice.

Efficiency of 3 N sources in rice variety Rasi in a submerged Vertisol. Rajendranagar, Hyderabad, India, 1988 DS.

Available N a content in soil (kg/ha) N uptake by rice Rice

Days after transplanting yield N source (kg/ha) grain

2 7 14 28 42 56 PI Maturity (t/ha)

None 10.9 13.4 13.4 7.5 7.4 1.3 49.4 69.0 3.9 Urea b 46.8 42.2 39.1 17.0 3.8 2.7 91.6 146.0 6.6 Sesbania 20.1 20.5 20.7 15.2 4.7 2.1 70.9 102.1 5.1 Gliricidia 18.6 22.2 22.2 29.2 4.8 2.7 87.0 114.2 5.7

LSD (0.05) 4.3 2.9 3.8 2.6 1.0 0.9 9.0 8.2 0.8

a 2 M KC1 extractable NH,-N in 015 cm plow layer. b Applied in two equal splits at transplanting and 57 d later.

Table 1. DMP and P and SiO2 content of rice when LFA was applied in lateritic sandy clay

Effect of lignite fly ash (LFA) on rice B. Raghupathy, Soil Science and Agricultural Chemistry Department, Faculty of Agricul- ture, Annamalai University, Tamil Nadu (TN),lndia

We evaluated the effect of LFA on dry matter production (DMP) of rice cultivar IR20 grown in a lateritic sandy clay loam soil in Kadampuliyur village, South Arcot District, TN, during Jun-Sep 1987 and Dec 1987-Apr 1988. Analysis of LFA (obtained from Thermal Power Plant, Neyveli, TN, India) indicated pH of 10, EC 1.0 dS/m, 49% SiO2, 12% CaO, 6.3% MgO, 8.3% K 2 O, 300 ppm

available SiO 2 , and no N and P.

0.1 dS/m, 0.17% organic C, 70 ppm available SiO 2 (low), 70 ppm available N (low), 2.8 ppm Olsen’s P (low), and 83 ppm available K (low). Soil was air- dried, sieved, and put into clay pots at 10 kg/pot. In the first season, LFA was applied at 5 g/pot (1 t/ha). Nutrient treatments were N, NP, NK, and NPK, with and without LFA (Table I). The experiment was laid out in a completely randomized design with four replications.

which were then submerged for 10 d. We applied N as urea at 40 ppm, P as

The experimental soil had pH 5.5, EC

Rainwater was added to the pots,

loam soil. a 1987.

Nutrient content Treatment DMP

(g/pot) P SiO 2 (ppm) (%)

N 11.07 c 295 e 3.09 N + LFA 11.36 c 350 c 3.95 N+P 13.39 bc 323 d 2.90 N + P+ LFA 14.83 b 362 c 3.11 N+K 9.56 d 309 de 2.95 N + K + LFA 10.74 b 421 b 2.40 N + P + K 15.99 cd 328 d 3.16 N+P + K 22.70 a 569 a 2.86

LSD (P=0.05) 3.09 19 ns b + LFA

a Values followed by the same letter are not significantly different at the 5% level by DMRT. b ns = not significant.


Fertilizer management

Fertilizer management-inorganic sources

Table 2. Effect of LFA and added P soil. 1988.

on grain and straw yields of lR20 in lateritic sandy clay loam

Yield Treatment LFA (g/pot) Grain % increase Straw % increase

(g/pot) (g/pot)

p (0 ppm) No added LFA 16.29 20.47

2.5 17.48 7.3 22.68 10.8 5.0 23.07 41.6 27.72 35.4 7.5 16.81 3.2 17.64 –13.8 Mean 18.81 22.12

P (13 ppm) No added LFA 17.25 25.08

2.5 19.31 11.9 24.23 5.0

–3.4 23.62 36.9 33.40 33.2

7.5 16.07 –6.8 17.18 –31.5 Mean 19.06 24.97 LSD (P = 0.05)

diammonium phosphate at 13 ppm, and flooded condition. K as sulfate potash at 11 ppm. pot, and allowed to grow for 50 d under

Twenty-day-old rice seedlings raised LFA combined with NPK resulted in in the experimental soil were transplanted the highest DMP (22.7 g/pot), which was at two seedlings per hill, three hills per about 42% more than that of NPK alone

(Table I). P content was consistently higher when LFA was added. LFA with N, P, K, and their combinations did not influence SiO2 content in rice plants.

Apr 1988 incorporated 0,2.5, 5.0, and 7.5 g LFA/pot (0,0.5, 1.0, and 1.5 t/ha) with 13 ppm P and no P. The experiment was conducted using a completely randomized design with three replications. N at 40 ppm and K at 1 1 ppm were

Another pot culture trial in Dec 1987-

applied to all pots. Regardless of P treatment, LFA at 5 g/

pot gave the highest grain yield, followed by LFA at 2.5 g/pot (Table 2). Applying P with LFA at 2.5 g/pot increased grain yield, but at 7.5 g LFA/pot, yields were reduced by 6.8% compared with no LFA.

Straw yield was markedly increased with 5 g LFA/pot with or without P. LFA at 7.5 g/pot adversely affected straw yield.

Silicicolous plants, such as rice, can benefit from up to 1 t LFA/ha, particularly in lateritic acid soils.

Fifteen of the 136 strains dried on paper strips lost viability after at least 5

Using desiccation to preserve

bench. Paper strips were stored in plastic were viable after 4 yr. The paper strip after another 6 mo, and none of the strains and dried in a convection flow clean mo of storage. The number increased to 30 of Whatman chromatography paper no. 3

S. S. Ardales, IRRI; and P. A. Roger, lnstitut bags at room temperature. method should only be used for short-term Français de Recherche Scientifique pour le Mass cultures were produced in 12 preservation. Developpernent en Cooperation, Laboratoire liters of medium exposed to continuous de Microbiologie. Universite de Provence, Case 87, 3 Place Victor Hugo, F-13331 illumination, stirring, and bubbling of an viable after 9 yr of storage. As with the Marseille Cedex 3, France air-CO2 mixture. Cultures were decanted soil-based cultures, the populations

and centrifuged after 4-6 wk of growth. decreased tremendously over time; higher We wanted to find a suitable method to They were dried slowly under fluorescent aliquot parts and longer incubation periods preserve BGA in the dry state as an lamps and later ground and stored in were required to obtain growth. The best alternative to frequent subculturing of plastic bottles. method for preserving BGA in the dry fresh cultures. We produced soil-based Viabilities of the dried cultures were state is the powdered mass culture, which cultures, cultures deposited on paper strips, tested by incubating aliquot parts of the has the advantages of unialgality and and mass cultures and tested their soil-based and mass cultures in 25-ml retention of viability for up to 9 yr. viabilities after long storage. erlenmeyer flasks containing 5 ml of

Soil-based cultures were produced in medium. For cultures on paper strips, 250-ml erlenmeyer flasks or on petri plates 0.5-cm portions were cut and incubated Effects Of Sesbania aculeata (14 cm diam). A loopful of culture was like the other cultures. (dhaincha) on rice yield inoculated into a previously autoclaved Of the 65 soil-based cultures, 58 mixture of 100 ml BG-11 0 medium and 20 g soil. Cultures were incubated under disadvantage of using soil as a base is the Hisar 125004, lndia continuous illumination for 4 wk and then presence of contaminants. About 40% of dried slowly. Cultures were ground and the cultures were contaminated with either We studied how rice yields were affected kept in plastic bottles at room temperature. diatoms, BGA (notably Nostoc sp.), or by green manuring with dhaincha and by

To preserve strains on paper, 6- to 12- both. Soil must be sterilized completely to incorporating green manure (GM) with wk-old liquid cultures were deposited remove indigenous flora when using this graded doses of N, P, K, and Zn (see aseptically on to sterile strips (2 × 7.8 cm) preservation method. table).

blue-green algae (BGA)

Powdered mass cultures remained

J. C. Sharma and M. S. Kuhad, Soil Science remained viab1e after 6 yr of storage. A Department, Haryana Agricultural University,


Fertilizer management—organic sources

Effect of graded doses of NPK with and without dhaincha on rice yield, yield attributes, and profit. a Hisar, India.

12.5 t dhaincha/ha + 180 N + 13.2 P + 125 N + 27.28 P + 120 N + 13.2 P + 24.9 K + 5.75 Zn 51.46 K + 5.75 Zn LSD 24.9 K + 5.75 Zn b kg/ha kg/ha 0.05 Comparative yields and N

uptake in six transplanted kg/ha

8.7 8.2 7.4 0.4 and direct seeded lowland Rice yield (t/ha)

Increase in yield 1.3 0.8 rices

(t/ha) over 125 kg N/ha treatment

Increase in yield (t/ha) over 180 kg N/ha treatment

Expenditure on fertilizer, including dhaincha (US$/ha)

Yield price (US$/ha)

0.4

65.30 51.70 50.85

880.57 836.79 753.32

D. K. Kundu, K. V. Rao, and K. G. Pillai, Directorate of Rice Research (DRR), Rajendranagar, Hyderabad 500030, Andhra Pradesh (AP), lndia

We compared yields and N uptake of six rice varieties in a submerged Entisol under transplanted and direct seeded cultures. The field experiment was conducted on Manmool clay soil (deep aquic Ustorthent) with pH 6.6 and 0.13%

Increase in profit 112.80 82.62 (US$/ha) over 125 kg N/ha treatment

Increase in profit 30.18 (US$/ha) over 180 kg N/ha treatment

Benefit-cost ratio over 125 kg N/ha treatment 8.8:1 180 kg N/ha treatment 3.2:1

Yield attributes Plant height (cm) 85.6 1,000-grain wt (g) 26.0 Tillers (no.) 18.0

total N at the Ramachandrapuram farm of DRR during the 1990 wet season (WS).

The experiment was laid out in a split- plot design, with direct seeded rice and transplanted rice in the main plots. Subplot treatments were the six varieties. Rice was direct seeded at 100 kg seed/ha. Pregerminated seeds were broadcast in half of the main field and in nursery beds on 10 Jul. No standing water was allowed

88.5 85.7 25.9 25.0 ns c

17.6 16.9 ns kept at 5-7 cm during the growing

in the direct seeded plots for 2 wk during 0.79 seedling establishment. Water level was

Soil data (postharvest) pH (1:2) 8.2 8.4 8.3 ns EC (1:2) 0.12 0.14 0.16

Available P (kg/ha) 7.20 8.00 8.80 Available K (kg/ha) 250 253 268

OC (%) 0.24 0.23 0.22

a Price (US$/kg): N = 0.19, P = 0.22, K = 0.08, Zn = 0.34, rice = 0.10. Expenditure on all agricultural operations = US$292.95/ha. b Zn = zinc sulfate. c ns = not significant.

Soil of the experimental field was

significantly more than 125 kg N/ha and (DTPA extractable). GM and 120 kg N/ha yielded extract). Available Zn was 0.58 ppm

was 0.3 ha. available K/ha (ammonium acetate three replications. The experimental plot P/ha (NaHCO 3 extract), and 260 kg laid out in randomized block design with permanganate method), 9.0 kg available after transplanting. The experiment was 100 g soil, 150 kg available N/ha (alkaline applied in two equal splits at 3 and 6 wk C, EC (1:2) 0.15 dS/m, CEC 10.5 meq/ transplanting. The remaining N was Ustochrept) with pH 8.3,0.30% organic doses of P, K, and Zn were applied at classified as sandy loam (Typic

One-third of the N as urea and full

Dhaincha sown in another field was about the same as 180 kg N/ha. This cut at 45 d, transported, and incorporated resulted in a net profit of US$30/ha (see into the soil at 12.5 t/ha. N was 1.1% of table). fresh biomass. Rice variety HKR-120 (145 d) was planted in the field.

season. Three-week-old seedlings were

transplanted at 20- × 1 5-cm spacing in the remaining half of the main field on 3 Aug. Eighty kg N, 17 kg P, and 33 kg K/ha were uniformly applied. All of the P and K were applied to the field 1 d before seeding or transplanting. N was applied in three splits for the direct seeded crop: 25% at seeding, 25% at 3 wk after seeding, and 50% at panicle initiation (PI). N was applied in two equal splits at planting and at PI in the transplanted crops. Grain and straw were sampled at maturity to determine total N uptake.

Grain and straw yields did not vary significantly with crop establishment method. Sasyashree produced significantly higher straw and lower grain yields than did the other varieties. Culture type and variety had significant interaction effect on straw yields but not grain yields. Rasi and IET9219 produced more straw under direct seeding than


Crop management

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Net profit (US$/ha) 522.32 492.14 409.52

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under transplanted culture. Straw yield of Sasyashree was higher than that of

Yields and N uptake of six rice varieties under two cultures in a submerged Ustorthent.

Total N uptake (kg/ha) Variety performed equally well when they were

Grain yield (t/ha) Straw yield (t/ha) Vikash in direct seeded culture, but they

Ramachandrapuram, AP, India, 1990 WS.

DS a TP b Mean DS TP Mean DS TP Mean transplanted. Neither culture type nor variety

significantly influenced total N uptake in rice, although their interaction effect was significant. N uptake in Vikash was significantly more under transplanted condition than that of IET7959, but in direct seeded culture, the opposite was true. Vikash and IET9978 can be used for direct seeding. The two varieties also removed significantly less N when direct seeded than when they were transplanted (see table).

Rasi 4.6 Sasyashree 4.0 Vikash 4.4 IET7959 4.6 IET9219 4.9 IET9978 4.4 Mean 4.5

LSD (0.05) Culture (C) Variety (V) C × V C at same V V at same C

4.1 3.5 4.4 4.2 4.3 4.4 4.2

ns c

0.34 ns

4.4 4.2 3.3 3.7 89.8 3.7 4.8 4.5 4.7 86.2 4.4 3.9 4.4 4.1 78.4 4.4 3.7 3.4 3.6 88.8 4.6 4.2 3.4 3.8 85.6 4.4 3.8 3.8 3.8 79.4

4.1 3.8 84.7

ns 0.44

0.72 0.62

a DS = direct seeded. b TP =transplanted. c ns = not significant.

85.6 87.7 82.4 84.3 89.9 84.1 81.5 85.1 81.7 83.7 92.3 85.8 85.6

ns ns

10.0 8.0

We used the method of Matsuida et al

Occurrence of rice grain rot grown in the Red River Delta was disease in Vietnam

Variety CR203, which is widely

Ha Minh Trung, Nguyen Van Van, Ngo Vinh Vien, Do Thanh Lam, and Mai Lien, Plant Protection Research Institute (PPRI), Chem, Tu Liem. Hanoi. Vietnam

Rice grain rot disease has caused damage in Japan, Taiwan, Philippines, and Latin America. The disease causal organism is bacterium Pseudomonas glumae. Symptoms are discolored grain, husk, and endosperm. Grain is unfilled in severely infected plants.

The disease was first recorded in Vietnam in 1991 early summer rice season in the central provinces and in the summer rice season in the Red River Delta provinces. PPRI studied the disease etiology and its distribution. About 100,000 ha were infected in 1992 early summer and summer seasons. Five provinces (Ha Tay, Thai Binh, Nam Ha, Thanh Hoa, and Khanh Hoa) are reported to be disease hot spots, with crop losses

To confirm the causal agent of the disease, infected grains were collected. Two botanic parasitic bacteria were isolated and identified in the laboratory. One had a yellow colony and the other, a creamy white colony. Seedborne fungi Cercospora, Helminthosporium, and Curvularia were also isolated.

of up to 75%.

artificially inoculated at the heading stage. Only the bacterium with the creamy white colony at 10 8 cfu/ml concentration produced symptoms similar to the disease observed in the field; it was designated as isolate no. 18.

Treating rice seeds with fungicides and antagonists to control seedborne diseases D. Geetha and K. Sivaprakasam, Plant Pathology Department, Agricultural College and Research Institute, Madurai, Tamil Nadu 625104, India

Rice blast (Bl), caused by Pyricularia oryzae Cav., and brown leaf spot, caused by Helminthosporium oryzae Breda de Haan, are seedborne diseases that cause appreciable yield loss. We treated rice seeds with some fungicides and antagonists to assess effects on seed viability, seedling vigor, and inhibition of seedborne pathogens.

We conducted standard blotter assays using seeds of rice cultivar ADT36. P. oryzae infected 27.0% of the seeds and H. oryzae, 35.4%. Seeds were treated with fungicides and antagonists (see table), shade-dried, and stored for 5 mo. Seed viability and seedling vigor were

to detect P. glumae using a CaC 2 O 4 crystal. We cultured isolate no. 18 in a potato-peptone-glucose-agar (PPGA) mixed medium and with 0.1% CaCl 2 at 38 °C. The color of the PPGA turned a pale greenish yellow, and the CaC 2 O 4 crystal on the colony was observed under the microscope. P. glumae was identified as the causal organism.

assessed monthly for 6 mo by roll towel method. Inhibition zone assay was used to determine inhibition of pathogens.

In the roll towel method, 10-d-old normal seedlings were selected randomly and root length, shoot length, and dry weights were measured.

Vigor index (VI) was calculated as

VI = Germination % × root length (mean of 10 seedlings, in cm)

= Germination % × shoot length (mean of 10 seedlings, in cm)

= Germination % × dry weight (mean of 10 seedlings, in mg).

In the inhibition zone assay, the spore suspension (10 6 spores/ml) of the test pathogen ( P. oryzae or H. oryzae ) was mixed with molten potato dextrose agar medium and poured in petri plates. A treated seed was placed at the center of the medium. The diameter of the


Integrated pest management-diseases

Effect of treating seed with chemicals and antagonists on inhibiting seedborne pathogens and on gemination, root length, shoot length, dry weight, and vigor indices. a

Treatment

Fungicide Pyroquilon Pyroquilon Pyroquilon Tricyclazole Tricyclazole Tricyclazole Carbendazim Carbendazim Carbendazim Carboxin Carboxin Carboxin Mancozeb Mancozeb Mancozeb Thiram Thiram Thiram

Concentration (%)

0.1 0.2 0.3 0.1 0.2 0.3 0.1 0.2 0.3 0.1 0.2 0.3 0.2 0.3 0.4 0.2 0.3 0.4

Diameter of inhibition

zone for P. oryzae

(mm)

22.90 c 30.11 ab 30.77 a

27.44 b 27.50 b 15.22 ghi 21.56 cd 22.11 cd 14.83 hi 18.22 efg 19.06 def 14.11 i 19.67 def 19.72 def 12.28 i 15.06 hi 17.50 fgh

20.45 c-f

Diameter of inhibition

zone for H. oryzae

(mm)

15.47 b 18.39 g 19.33 fg 21.94 def 25.06 cd 26.39 bc 22.22 def 24.11 cde 25.00 cd 21.67 ef 22.94 de 24.00 cde 29.50 b 33.28 a 33.00 a 18.50 g 23.33 cde 24.84 cde

Germi- nation

(%)

95.11 ab 94.89 ab 93.78 b 94.67 ab 96.00 ab 95.56 ab 95.34 ab 97.11 ab 97.33 a 96.00 ab 95.78 ab 96.00 ab 94.67 ab 95.56 ab 95.34 ab 96.22 ab 97.11 ab 96.45 ab

Root Shoot length length (cm) (cm)

16.12 fg 6.22 a 16.50 efg 6.49 a 16.37 fg 6.05 a 16.99 dg 6.61 a 18.81 a-f 7.18 a 18.60 a-f 6.85 a 21.05 ab 7.77 a 21.77 a 7.90 a 20.53 abc 7.23 a 17.50 c-g 7.01 a 20.31 abc 7.59 a 19.77 a-e 7.59 a 16.53 efg 6.82 a 17.82 bg 7.31 a 18.73 a-f 7.67 a 19.76 a-e 6.84 a 20.39 abc 7.67 a 20.03 ad 7.61 a

Vigor index Vigor index Vigor index Dry based on based on based on

weight root length shoot length dry matter (mg) and percent and percent and percent

germination germination germination

151.70 jk 1536.16 q 592.55 p 14441.78 q 152.44 j 1565.90 p 616.67 o 14471.78 p 150.17 jkl 1536.22 q 568.25 q 14088.17 r 158.22 i 1610.47 o 625.92 n 14989.56 o 164.61 gh 1808.12 j 689.65 i 15011.33 n 161.56 h 1782.84 I 655.10 I 15446.89 m 175.56 ab 2054.78 b 755.73 b 17091.55 b 176.22 a 2119.58 a 769.75 a 17156.67 a 174.67 ab 1972.14 d 727.91 f 16771.33 e 165.61 fg 1674.35 n 669.17 j 15830.67 k 174.61 ab 1909.41 f 735.02 d 16884.22 c 172.94 bc 1892.87 h 694.81 h 16535.33 g 165.61 fg 1562.86 p 646.74 m 15642.67 I 169.61 de 1703.46 m 699.04 g 16209.78 i 171.44 cd 1786.86 k 731.94 e 16347.11 h 173.72 abc 1901.47 g 658.44 k 16719.77 f 175.03 ab 1980.98 c 745.37 c 17093.94 b 174.61 ab 1941.22 e 735.00 de 16859.55 d

Antagonists Bacillus subtilis 60 × 10 9

cfu/ml 15.06 hi 18.50 g 93.78 b 16.15 fg 5.99 a 149.33 kl 1515.89 r 562.49 r 13930.22 s Pseudomonas 60 × 10 9

fluorescens cfu/ml 14.83 hi 19.83 fg 93.78 b 16.11 fg 6.04 a 147.78 Im 1512.69 s 553.41 s 13857.28 t Carbendazim 60 × 10 9 21.22 cde 23.17 cde 94.67 ab 19.67 a-e 6.54 a 167.94 ef 1858.51 i 619.47 o 15939.78 j

(0.2%) + cfu/ml Bacillus subtilis

Control 0.00 j 0.00 i 88.45 c 15.15 g 5.73 a 144.94 m 1341.63 t 507.18 t 12889.00 u LSD (P = 0.05) 0.66 0.68 3.40 0.07 0.02 0.90 46.30 11.80 282.69

a Av of 3 replications of 6 mo of observations. Values followed by different letters in each column are significantly different (P = 0.05) by DMRT.

inhibition zone that developed around the seed was measured.

Seeds treated with pyroquilon (0.3%) had the largest inhibition zone for P. oryzae, followed by tricyclazole (0.3%), mancozeb (0.4%), and carboxin (0.3%). Seeds treated with mancozeb (0.4%) had the largest inhibition zone for H. oryzae, followed by tricyclazole (0.3%). Carbendazim and carboxin (both at 0.2 and 0.3%) also inhibited the pathogens (see table).

vigor than untreated seeds. Seedlings raised from seeds treated with carbendazim (0.2%) and mancozeb (0.4%) had the best seedling vigor.

It is advisable to treat seeds with either pyroquilon or tricyclazole (0.2%) in areas

Treated seeds showed higher seedling

where B1 and brown leaf spot disease are severe. These fungicides effectively inhibit the pathogens while maintaining vigorous seedlings. Significantly higher seedling vigor, germination percentage,

Effect of foliar spraying of Aspergillus terreus Thom on sheath blight (ShB) and rice plant characteristics R. Gogoi and A. K. Roy, Plant Pathology

Jorhat 785013, Assam, India

aqueous spore suspension spray in

solani Kuhn).

Department, Assam Agricultural University,

We tested the efficacy of A. terreus as an

reducing incidence of ShB (Rhizoctonia

and inhibition of seedborne pathogens can also be obtained by treating seeds with carbendazim (0.2%) and mancozeb (0.3%).

The experiment was conducted during 1988 and 1992 ahu seasons (Apr-Aug). Twenty-six-day-old seedlings of rice cultivar IR50 were transplanted into 25-cm-dim clay pots containing 5 kg ricefield soil. A. terreus conidial suspension (47 × 10 6 spores/ml in 1988 and 49 × 10 6 spores/ml in 1992) was sprayed on foliage 38 d after transplanting in three ways: 3 d after, 3 d before, and simultaneously with inoculation of R. Solani. R. solani


ShB lesion size (mm2) after treatment with foliar spray of A. terreus spore suspension. Assam, India, 1988 and 1992 ahu seasons.

Days after 1988 1992 spraying A. terreus R. solani R. solani R. solani R. solani Mean a R. solani R. solani R. solani R. solani Mean (no.) alone + A. terreus + A. terreus + A. terreus alone + A. terreus + A. terreus + A. terreus

spray 3 d on same spray 3 d spray 3 d on same spray 3 d later day before later day before

3 10.67 8.85 9 11.25 10.50

15 11.68 11.70 21 12.70 12.08 27 14.05 15.68 33 16.80 16.04 39 17.85 16.51 45 18.14 17.07 75 20.70 18.15

Mean 15.86 a 14.06 b LSD (0.05): Inoculation (I)

days (D) I × D

4.50 8.52

12.24 12.34 14.15 14.64 14.79 15.22 15.78 12.46 c

0.81 1.40 ns b

0.71 4.52 8.70 9.54

11.01 11.45 12.41 13.06 13.16 9.36 d

6.18 a 8.41 8.69 b 11.55

11.08 a 12.42 11.66 c 15.19 13.72 d 16.01 14.73 d 18.14 15.39 d 20.16 15.87 de 20.23 16.97 e 21.53 15.96 a 15.96 a

1.82 3.16 ns

8.78 10.25 11.87 13.11 14.91 16.36 16.94 17.24 17.80 14.03 b

4.76 8.05 9.96

11.14 12.59 13.40 14.24 14.52 14.79 11.49 c

0.71 4.35 6.41 9.33

11.53 12.68 13.40 13.91 14.00

9.59 d

5.41 a 8.55 ab

10.17 bc 12.19 cd 13.76 de 15.14 def 16.18 ef 16.48 ef 17.03 f

a Means followed by different letters are significantly different at the 5% level by DMRT. b ns = not significant.

inoculation without A. terreus served as control. Plants were inoculated with R. solani by inserting 12-d-old sclerotium (grown on potato dextrose agar) between individual sheath and culm. ShB incidence was recorded up to 75 d after spraying with A. terreus (see table).

Foliar spraying of A. terreus reduced ShB infection in all treatments in both years (see table). Maximum reduction, was obtained when A. terreus was sprayed before R. solani. Spraying after R. solani inoculation was the least

effective treatment. Significant differences existed among days of observation, with disease incidence progressively increasing with time.

days after inoculation on disease incidence were significant. Differences among treatments were shown at many points along the disease progress curve.

Plant height and yield in 1988 and 1992, and dry weight of plant in 1992 were significantly greater in plants receiving A. terreus treatments than in the

Effect of sequence of inoculation and

Effect of foliar sprays of A. terreus spore suspension on growth characters of rice plants inoculated with R. solani. a 1988, 1992. a Means in a column with a common letter are not significantly different at the 5% level by DMRT.

control (see figure). Greater increases for all characters were obtained when A. terreus was sprayed either before or simultaneously with R. solani inoculation than when it was sprayed after R. solani inoculation.


Efficacy of botanicals in managing sheath rot (ShR) of rice V. Narasimhan, V. V. Sridhar, and A. Abdul Kareem, Tamil Nadu Rice Research Institute, Aduthurai 612101, lndia

The efficacy of neem derivatives and leaf extracts of Prosophis juliflora L. (10%) and Ipomoea cornea L. (10%) on ShR caused by Sarocladium oryzae (Sawada) W. Gams & D. Hawksw., was evaluated using susceptible cultivar Co 43 in the field in 1990-91 and 1991-92 wet seasons (WS). Neem derivatives were neem seed kernel extract 5% (NSKE), neem oil 3% (NO), and neem formulation 3% (NF) from Tamil Nadu Agricultural University. Leaf extracts and standard fungicide carbendazim (0.1%) were applied as foliar sprays at booting and 10 d later. Neem cake (NC) at 150 kg/ha and neem cake-coated urea (NCU) at 150 kg NC/ha + 75 kg N/ha were applied to the soil at planting. Each treatment was replicated three times. Plots were 5 × 4 m 2 .

percentage of tillers affected in 25 ShR incidence was measured as the

Effect of botanicals on ShR incidence and grain yield of rice. a Aduthurai, India. 1990-92 WS.

Treatment Mean ShR (%) Mean grain yield (t/ha)

Dose 1990-91 1991-92 1990-91 1991-92

Neem cake, basal Neem cake, basal +

neem seed kernel extract 5% FS b

Neem seed kernel extract - FS

Neem cake-coated urea, basal

Neem oil - FS Prosophis leaf extract FS lpomoea leaf extract FS Neem formulation Carbendazim Untreated check

150 kg/ha 20.9 ab Neem cake at 18.2 a 6.2 a

c 5.6 bc

150 kg/ha + FS 5%

5% 17.6 a 27.7 a 6.2 a 5.0 a

Neem cake at 25.4 ab 6.0 ab 150 kg/ha + urea at 75 kg N/ha

3% 23.7 ab 29.4 a 5.6 bc 4.1 d 10% 26.3 b 28.3 a 5.3 bc 4.7 abc 10% 23.9 ab 30.9 a 5.9 ab 4.5 bcd 3% 29.0 a – 4.5 cd 0.1% 17.6 a 27.0 a 6.1 a 5.1 a

40.0 c 41.9 b 5.2 c 3.7 e

a Values after angular transformation. Values having a common letter in a column are not significantly different at the 5% level by DMRT. b FS =foliar spray. c Not tested.

randomly selected hills per plot at 20 d after the last spray.

year, the carbendazim treatment recorded

ShR in both years, (see table). NSKE Prosophis leaf extract. alone, NC + NSKE, and carbendazim NSKE applied as foliar spray is controlled ShR significantly better in the first year trial than in the second, which increasing grain yield.

promising for reducing ShR and

the highest grain yield, but did not All treatments significantly reduced significantly differ from NSKE and

was reflected in grain yield. In the second

New races of Xanthomonas oryzae pv. oryzae (Xoo) among strains representing major rice-growing areas of India and Nepal Faiz-Ur Rehman, Plant Pathology Department (PPD), University of Hawaii (UH), 3190 Maile Way, Honolulu, Hawaii 96822, USA; S. S. Gnanamanickam, Center for Advanced Studies in Botany, University of Madras, Madras 600025, India; T. B. Adhikari, Plant Pathology Department, lnstitute of Agricul- ture and Animal Science, Central Campus, Rampur, Chitwan, Nepal; and A. M. Alvarez, PPD, UH

We have studied the pathogenic variation of 122 Xoo strains (86 from India, 36 from Nepal) using IRRI’s standard differential rice cultivars IR8 ( Xa-11 ), IR20 ( Xa-4 ), IR1545-339 ( xa-5 ), CAS209 ( Xa-10 ), and DV85 ( xa-5, Xa-7 ). Strains were collected during the past 5 yr from various rice-growing areas in the Indian states of Andhra Pradesh, Bihar, Punjab, Tamil Nadu, Uttar Pradesh, and West Bengal,

and in the areas of Banke, Bara, Bardia, Bhairahawa, Butwal. Dang, Jhapa, Lamjung, Palpa, Parsa, Ratuahat, Syanja, and Tanahua of Nepal.

Plants of the differential cultivars were grown in a greenhouse at UH for 40-50 d. Suspensions of 24-48 h bacterial cultures were adjusted to 2 × 10 8 colony forming units/ml. Plants were inoculated in replicated experiments using the scissor clip inoculation technique. Inoculated plants were kept under controlled conditions (28 °C temperature and 75% relative humidity) that favored both plant and disease development. Data on lesion lengths were recorded 14 d after inoculation, averaged, and rated as resistant or susceptible (see table).

groups based on average lesion length. Nepalese strains NXO200 and NXO216 did not fit any of the above pathogenicity patterns and were not assigned a group designation. None of the Nepalese strains tested corresponded to the previously reported race groups of N1 and N2 from

One hundred twenty strains formed six

Nepal because they were not based on the rice differentials that we used in our study. Groups la, lb, and 2 from the present study, however, corresponded to the previously reported Indian races Ia, Ib, and II, respectively. The reaction patterns of groups 3,4, and 5 are new and have not been previously reported from these areas. Based on these findings, we are proposing to designate group 3, which included two Indian and eight Nepalese strains, as Indian race III, and the relatively small group 4, which included three Indian and one Nepalese strain, as Indian race IV. We have not assigned a race designation to the 11 Indian and 11 Nepalese low-virulence strains that formed group 5. If tested on some indigenous rice cultivars, this group of strains might be found virulent and have some significance. Notably, none of the 36 Nepalese strains tested belonged to Indian race Ib.

The discovery of two new races and a low virulence group may be useful in breeding for resistance against Xoo in India and Nepal.


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– –

– –

Differential rice cultivar reactions to Xoo strains.

Range of av lesion length and disease reaction a

Group Strain (no.) IR8 (Xa-11) IR20 (Xa-4) lR1545-339 (xa-5) CAS209 (Xa-10) DV85 (xa-5, Xa-7) designation

Indian strains 86 Group 1a 5 13.0–28.0 (S) 3.0– 7.0 (R) 13.0–20.0 (S) 33.0–40.0 (S) Group 1b 27 16.0–24.0 (S) 10.0–15.0 (S) 11.0–17.0 (S) 31.0–40.0 (S) Group 2 38 19.0–23.0 (S) 11.0–17.0 (S) 17.0–21.0 (S) 20.0=39.0 (S) Group 3 2 10.0–18.0 (S) 3.0– 7.5 (R) 14.0–25.0 (S) 19.0–43.0 (S) Group 4 3 11.0–23.0 (S) 3.0– 3.5 (R) 3.0– 9.0 (R) 23.0–46.0 (S) Group 5 11

Race

7.0– 9.0 (R) la 7.0– 8.5 (R) Ib

31.0–36.0 (S) II 23.0–40.0 (S) III 6.0– 8.0 (R) IV

1.0– 3.5 (R) 1.0– 4.0 (R) 3.0– 5.0 (R) 1.0– 4.0 (R) 1.0– 5.0 (R)

Nepalese strains 36 Group 1a 7 Group 1b 0 Group 2 7 Group 3 8 Group 4 1 Group 5 11 NX0200 1 NX0216 1

10.4–16.0 (S) (S)

10.2–23.0 (S) 10.9–21.3 (S) 10.5 (S)

6.8 (R) 10.5 (S)

1.3– 8.4 (R)

2.1– 7.7 (R) (S)

10.6–21.0 (S) 1.8–6.3 (R) 2.2 (R)

2.1 (R) 5.5 (R)

1.0– 2.7 (R)

10.3–21.7 (S) (S)

10.9–20.4 (S) 13.0–19.6 (S)

5.1 (R)

3.6 (R) 7.5 (R)

1.4– 6.1 (R)

10.5–24.6 (S) (S)

11.6–24.1 (S) 14.8–19.3 (S) 10.3 (S)

12.4 (S) 10.8 (S)

2.2– 9.6 (R)

3.0– 7.6 (R) la (R) Ib

13.9–25.9 (S) II 14.8–22.1 (S) III 7.6 (R) IV 1.4– 9.4 (R)

10.6 (S) 13.6 (S)

a R = resistant (<10-cm lesion length), S = susceptible (>10-cm lesion length).

number of bugs/five sweeps of a net. Only four rice bugs were recorded in the

Effects of neem and nochi on botanical pest control products on rice malathion-sprayed plot, which had a rice bug Leptocorisa acuta bug during the second season (Sep 1991- population reduction of 86.2% compared

Feb 1992). The insecticide malathion with the control. The next best treatment

neem seed kernel extract, and nochi were C. Durairaj, National Pulses Research

table). The experiment was laid out in a Centre, Vamban Pudukkottai 622303 and 50 EC was included for comparison (see was Neemark, with S bugs. Neem oil,

M. S. Venugopal, Agricultural Entomology Department, Agricultural College and Research Institute, Madurai 625104, India plots and three replications. Neemark.

We conducted a field experiment using bug populations were assessed as the IR20 to study the effects of Azadirachta

randomized block design with 20-m 2 much less effective than malathion and

Twenty-four hours after spraying, rice

indica (neem) and Vitex negundo (nochi)

Effect of botanical pest control products feeding tiger moth on rice bug populations. Madurai, India, host plant range of rice- Developmental biology and non-airconditioned headhouse.

Temperature averaged 26.9 ± 1.06 °C. Relative humidity averaged 73.2 ± 4.0%. 1991-92.

Creatonotus gangis (L.) Host suitability was determined as

Treatment

Malathion 0.05% Neemark 0.5% Neem oil 2.0% Nochi leaf

extract 2.5% Nochi leaf

extract 5.0% Neem seed

kernel extract 5.0%

Control CD (P = 0.05)

a Mean of three replications.

Rice bug Decrease (no./ over 5 net control

sweeps) a (%)

4.0 86.2 5.0 82.8 9.0 69.0

14.3 50.7

18.0 38.0

17.7 39.0 29.0

2.54

J. L. A. Catindig, A. T. Barrion, and J. A. Litsinger, IRRI

We studied the development of C. gangis on 20 common plant species from families Poaceae (14), Cyperaceae (5), and Commelinaceae (1). Unfed neonate larvae were placed on 25- to 30-d-old individual host plants in 20-cm-diam clay pots enclosed in 10- × 72-cm cylindrical mylar cages with top and side vents of nylon mesh (1 mm 2 ). Ten larvae were released per cage. Each cage served as a treatment, replicated 10 times, in a randomized complete block design in a

percentage of larval survival, larval developmental period, larval growth index, and eggs laid by emerging females.

Fecundity was determined on an individual basis for newly emerged moths, which were held in a 65- × 65- × 110-cm rectangular wooden cage frame with sides of nylon mesh (1 mm2). Honey solution (10%) was provided for food. A male was introduced for each caged female.

20 plant species, confirming the poly- phagous nature of this insect.

C. gangis survived to pupation on all


Integrated pest management-insects

–

–

–

– –

Table 1. Host plant range of C. gangis. IRRI headhouse, Feb-Mar 1990. a

Parameter Overall

Larval survival Larval developmental Larval growth Eggs laid ranking f

(%) bc period (d) d index (rating) e (no./female)

Poaceae TN1 rice Leptochloa chinensis (L.) Nees Maize Echinochloa colona (L.) Link E. glabrescens Munro ex Hook f. Eleusine indica (L.) Gaertn. lsachne globosa L. Paspalum scrobiculatum L. P. conjugatum Berg. Leersia hexandra Sw. Brachiaria mutica (Forsk.) Stapf. B. distachya (L.) Stapf. Chloris barbata Sw. lmperata cylindrica (L.) Beauv

79.0 ± 9.5 a 22.1 ± 0.8 a 73.0 ± 20.0 ab 23.7 ± 1.4 b 69.9 ± 12.0 abc 29.4 ± 0.9 c 63.0 ± 26.3 abc 30.2 ± 1.6 d 67.0 ± 18.3 abc 30.6 ± 0.9 e 72.0 ± 18.7 ab 31.5 ± 1.8 ef 53.0 ± 46.4 c 31.5 ± 1.0 ef 57.0 ± 22.1 bc 36.1 ± 1.2 fg 31.3 ± 16.0 d 29.1 ± 1.2 c 24.1 ± 23.2 de 31.5 ± 1.2 ef 15.0 ± 7.1 def 37.7 ± 0.9 gh 12.1 ± 11.4 ef 38.1 ± 1.4 gh 10.0 ± 0.0 ef 38.1 ± 1.2 gh 8.0 ± 4.2 ef 42.1 ± 1.6 i

3.5 ± 0.4 a 3.1 ± 0.9 ab 2.8 ± 0.5 bc 2.4 ± 1.0 cd 2.5 ± 0.7 bcd 2.8 ± 0.7 bc 2.0 ± 1.8 de 1.7 ± 0.7 ef 1.2 ± 0.6 h 0.9 ± 0.9 ghi 0.4 ± 0.2 ij 0.4 ± 0.3 ij 0.2 ± 0.0 j 0.2 ± 0.0 j

46.7 ± 40.7 a 45.8 ± 12.5 a

34.1 ± 9.3 a-e 36.2 ± 7.3 a-d

49.5 ± 38.9 a

36.7 ± 13.7 a-d 44.7 ± 6.7 ab 17.7 ± 7.1 e-h 16.2 ± 12.5 fgh 17.8 ± 1.7 e-h 6.1 ± 6.0 h

25.5 ± 18.9 c-g

21.5 ± 5.6 d-h

29.2 ± 15.8 b-f

1 2 3 4 5 6 7 8 9

12 13 14 15 18

Cyperaceae Cyperus kyllingia Endl. C. brevifolius (Rottb.) Hassk. Fimbristylis miliacea (L.) Cyperus iria L. C. rotundus L.

57.2 ± 24.5 bc 32.0 ± 1.6 f 1.7 ± 0.8 ef 38.3 ± 11.7 abc 10 52.1 ± 24.4 c 38.1 ± 1.2 gh 1.5 ± 0.7 efg 15.9 ± 4.6 fgh 11 19.0 ± 8.8 def 35.6 ± 0.7 fg 0.6 ± 0.3 h-j 11.7 ± 4.4 gh 13 22.0 ± 9.2 def 43.0 ± 0.7 i 0.6 ± 0.2 h-j 33.2 ± 11.9 a-e 16 4.0 ± 5.2 f 39.6 ± 1.1 h 0.1 ± 0.0 j 22.8 ± 6.3 c-g 17

Commelinaceae Commelina diffusa Burm. f. 4.0 ± 5.2 f 30.8 ± 0.7 e 0.1 ± 0.0 i 25.3 ± 7.0 c-g 19

a Av of 10 replications. In a column, means followed by a common letter are not significantly different (P < 0.01) by LSD statistical test.

b Suvival (%) = Larvae becoming pupae x 100. c n = 100. d n = 10. e Growth index = Larval survival (%) . f 1 = best, 19 = worst,

Total larvae Larval growth period (d)

Table 2. Life history of C. gangis. IRRI the most suitable host (Table 1). headhouse, Mar-Dec 1989. a

ovipositional hosts and supported x ± SD All the plant species served as

Egg incubation period (d) 4.6 ± 0.8 Larval stadium (d)

complete development of C. gangis. Greatest fecundity (no. eggs/female)

I

III IV V

4.5 ± 0.5

4.0 ± 0.7 globosa (49.5), rice (46.7), L. chinensis 4.7 ± 0.8 4.0 ± 0.5 (45.8), Leersia hexandra (44.7), Cyperus

Prepupa (d) Pupa (d)

2.0 ± 0 kyllingia (38.3), Paspalum conjugatum

Total developmental period (d) 37.2 ± 1.4 8.5 ± 0.5

Moth longevity (d) 12.0 ± 1.5 Eggs laid (no./female) a n = 100.

characteristics of brown

Highest larval survival to pupation immigrants to Japan

II 4.9 ± 1.3 occurred from moths reared on Isachne

46.7 ± 40.7 Shifts in population

planthopper (BPH)

(n = 100) occurred on rice (79%), Leptochloa chinensis (73%), and K. Sogawa, Laboratory of Pest Manage-

Eleusine indica (72%). The quickest ment Systems, Kyushu National Agricul- tural Experiment Station, Suya 2421,

larval developmental period was on rice Nishigoshi, Kumamoto 861-11, Japan (22.1 d), although on all other plant hosts development was significantly Hopperburn was observed for the first delayed. These two developmental time on a BPH-resistant breeding line parameters resulted in a high growth with Bph 1 gene in Japan in 1990, index for rice (3.5) and L. chinensis indicating that BPH immigrating to (3.1), which were significantly higher Japan may have changed significantly. than for the other plants. Rice (TN1) was This population shift was evaluated

(36.7), E. glabrescens (36.21, and E. colona (34.1) (Table 1).

Life history data for C. gangis developing on rice appear in Table 2.

Even though C. gangis is highly adapted to rice, it occurs rarely and has never been reported to be economically important.

quantitatively using 96 immigrants in 1992.

Honeydew excretion of adult females was measured individually. Insects were confined to leaf sheaths of rice at the early tillering stage with clip-on Parafilm sachets (about 1.5 × 1.5 cm) at 25°C for 1 d. The same insects were transferred daily from resistant IR26 (Bph 1 gene) to susceptible japonica Reihou to resistant IR42 ( bph 2 gene) to clarify the biotypic properties of individual females.

Individuals excreting at least 10 mg honeydew were tentatively classified as able to feed normally. Of the 92% that


Honeydew excreted by 96 adult female immigrants on Reihou, IR26, and IR42. Individuals were arranged in descending order based on amounts of honeydew excreted on Reihou. Japan, 1992.


fed normally on Reihou, 47% could feed

biotype 1. respectively. Only one female excreted biotype 2, and the rest were still Reihou and 33±18 mg on IR26, recent BPH immigrants to Japan were excreted daily was about 46±23 mg on

We conclude that about half of the IR42, and Reihou. Average honeydew 10 mg on Reihou and IR42 (see figure). on IR26, and 1% could feed on IR26, more than 10 mg on IR26, but less than

49 mg on IR42. Five females excreted

Detoxifying enzymes of the insects. brown planthopper (BPH) for glutathione transferase in other

Chien-Jung Gu, Wen-Lin Chen, and Chih- Ning Sun, National Chung-Hsing University, Taichung, Taiwan, Republic of China

Activity of microsomal P450- dependent monooxygenases toward several model substrates in BPH is very low-only about 1/50 to 1/100 of that in

Among the major detoxifying enzymes, hydrolases are the most studied group because of their involvement in the resistance of Nilaparvata lugens Stål to both organophosphorus and pyrethroid insecticides. Activity of carboxylesterase toward 1-naphthyl acetate in BPH is at least 20-fold higher than in some lepidoptera. More than a dozen carboxylesterase isozymes have been resolved using isoelectric-focusing electrophoresis, and substrate specificity has been observed in some isozymes.

Considerable conjugation of 1 -chloro- 2,4-dinitrobenzene mediated by glutathione transferase has been observed in BPH. This enzyme in the pest, however, does not show any detectable activity toward another model substrate, 1,2-dichloro-4-nitrobenzene, or insecticides (parathion, paraoxon, and methyl parathion) known to be substrates

some lepidopterous insects. It has been hypothesized that this low mono- oxygenase activity may be due to its contact with only water-soluble materials in plant saps (see table).

insecticide resistance observed in BPH may reflect the fundamental makeup of detoxifying enzymes. A lack of cross- resistance in BPH from existing organophosphorus/pyrethroid resistance (conferred by enhanced carboxylesterase hydrolysis) to buprofezin might be because the carboxylesterases do not hydrolyze this chitin synthesis inhibitor. Further, there may not be active microsomal monooxygenases with which to hydroxylate buprofezin, a known detoxifying reaction observed in soils. If resistance to buprofezin should occur in BPH, it might be the result of target site alterations.

The metabolic mechanisms of

Activities of detoxifying enzymes of Nilaparvata lugens Stal.

Enzyme and substrate Specific activity

Carboxylesterase 1-naphthyl acetate 2-naphthyl acetate

Glutathione transferase 1-chloro-2,4-dinitrobenzene 1,2-dichloro-4-nitrobenzene Parathion Paraoxon Methyl parathion

Aldrin Methoxyresorufin Ethoxyresorufin Ethoxycoumarin

Microsomal P450-monooxygenases

40.2 µmol/min per mg protein 36.9 µmol/min per mg protein

192 µmol/min per mg protein NDa

ND ND ND

3.75 pmol/min per mg protein 2.90 pmol/min per mg protein

ND ND

a ND = not detected.

Efficacy of benomyl in controlling the ufra nematode in Vietnam

Nguyen Thi Thu Cuc and Tran Vu Phen, Plant Protection Department, Can Tho University, Can Tho, Vietnam; and J.-C. Prot, IRRI

We conducted two experiments to test the effect of benomyl on the ufra nematode, Ditylenchus angustus, in deepwater rice in farmers' fields.

The first experiment was conducted in the village of Long Thanh My, Thu Duc district, Ho Chi Minh City. The farmer transplanted 45-d-old seedlings of variety Tieu doi in an ufra-prone area. Eight benomyl treatments were evaluated.

The second experiment was conducted, in Dong Phu, Chau Thanh district, Can Tho Province, in a field dry seeded with variety 1960. Rice showed ufra symptoms 40 d after sowing. Two benomyl and water solutions were tested: 0.1 and 0.2% ai sprayed at a rate of 500 liters/ha. An untreated control was the third treatment.

Fields were cultivated following farmers' practices. Experiments were laid out in a randomized complete block design with four replications using 7- × 7-m plots for the first experiment and 10- × 10-m plots for the second experiment. In the first experiment, 10 hills/plot were collected at rice crop maturity for nematode analysis. In the second experiment, five crop cuts of 20- × 20-cm were collected at random from each plot 1 d before, and 10 and 20 d after benomyl treatments. In both experiments, nematodes were extracted from all of the stems collected. Results were analyzed using ANOVA. Means were separated using DMRT.

D. angustus infestation was low in the first experiment, most probably because of late flooding and low water level during the flood. Results indicate,


Integrated pest management— other pests

however, that none of the benomyl

high. lower in benomyl-treated plots than in nematode counts per stem remained D. angustus numbers were significantly control the nematode effectively and (Table 1). In the second experiment, (Table 2). Benomyl, however, failed to treatments controlled the nematode untreated plots at both sampling times

Water management in transplanted wetland rice

Table 1. Number of D. angustus /hill observed at rice crop maturity after benomyl treatments. Department, Andhra Pradesh (AP), Long Thanh My, Thu Duc district, Ho Chi Minh City, Vietnam.

Treatment

S. C. Mastan and B. Vijaykumar, Agronomy

Agricultural University, Hyderabad 500030,

D. angustus /hill a India

(no.) We studied how water management

T1 Untreated 7.6 a b

T2 Seed treatment by soaking for 24 h in a solution of benomyl 8.4 a

practices affect grain yield and water use efficiency of transplanted rabi (winter)

at 0.1% ai rice. We studied the response of rice T3 T2 + spraying at 30 DT c with a solution of benomyl at 0.1 ai 26.6 a

T4 Seedling treatment by spraying with a solution of benomyl at 10.7 a

T5 T 4 + spraying at 30 DT with a solution of benomyl at 2.6 a

T6 Spraying at 30 DT with a solution of benomyl at 17 a

T7 T6 + spraying at flowering with a solution of benomyl at 4.2 a

T8 Spraying at 21 d after flooding with a solution of benomyl at 29.7 a

T9 Spraying at flowering with a solution of benomyl at 11.5 a

at a rate of 400 dm 3 /ha

0.1 ai 2 d before transplanting at a rate of 240 dm 3 /ha

0.1 ai at a rate of 400 dm 3 /ha





a Mean of 4 replications. b Means followed by a common letter are not significantly different at the 5% level by DMRT. c Days after transplanting.

Table 2. Number of D. angustus observed/stem before and after spraying benomyl at two concentrations 40 d after sowing. Dong Phu, Chau Thanh district, Can Tho Province, Vietnam.

D. angustus /stem a (no.) Treatment

1 d before 10 d after 20 d after treatment treatment treatment

Control (no benomyl spray) 33 a Benomyl 0.1% ai 30 a Benomyl 0.2% ai 32 a

83 a 64 a 45 b 44 b 42 b 43 b

a Mean of 4 replications. In a column, means followed by a common letter are not significantly different at the 5% level by DMRT.

crops subjected to various irrigation schedules and determined the most productive schedule when water is a limiting factor.

The experiment was laid out in a completely randomized design during 1989-9 1. No rain fell during the experiment. Thirty-day-old seedlings of Tellahamsa (1 20 d) were transplanted into 30-m 2 plots at Agricultural College Farm, Rajendranagar, Hyderabad. Soil was a clay loam. We applied 100:17.6:24.9 kg NPK/ha in three splits: 1/3 at transplanting, 1/3 at maximum tillering, and 1/3 at panicle initiation. Granulated butachlor (at 1.5 kg ai/ha) mixed with fine sand was applied at 4 d after transplanting (DT) and followed by handweeding at 30-35 DT.

Maintaining 5 cm of water yielded the most rice (5.5 t/ha) in the experiment but required 1,530 mm of the water. Applying 5 cm of water at 2 d after disappearance of ponded water (DADPW) did not reduce yield significantly, but it saved considerable water. 2 DADPW had the highest water use efficiency (5.41 kg grain/ha-mm) among treatments. Other treatments consumed less water than continuous submergence but yielded significantly less (see table). Severe cracks developed in these treatments and water stress occurred during and after panicle initiation.


Water management

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@IRRI.CGNET.COM"

Effect of water regime on grain yield of winter rice a . Rajendranagar, Hyderabad, India, 1989-91. Varietal diffusion in a rice Grain Water Water use farming system

Water regime

Continuous submergence (5 cm water) 5 cm water 2 DADPW b

5 cm water 3 DADPW 5 cm water 4 DADPW 5 cm water 5 DADPW

LSD (0.05)

yield (t/ha)

5.5 5.2 4.6 4.1 3.4 0.7

a Mean of 2 yr. b DADPW = d after disappearance of ponded water.

requirement (mm)

1530 935 850 765 680

efficiency (kg grain/ha-mm)

3.60 5.41 5.37 5.36 4.95

Seeds of mustard (cultivar B g ) at 8 kg/ha, grasspea (cultivar Nirmal) at 50 kg/ha,

Establishing rainfed no-till winter crops under NPK fertilization after transplanted wet rice N. R. Das and N. Bhanja, Agronomy Depart- ment, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia, West Bengal, India

We studied the feasibility of establishing crops after transplanted wet rice during winter without tilling and using only residual moisture.

factorial randomized block design, replicated four times, and conducted during winter seasons (1990-91 and 1991- 92) at the University Farm, Kalyani, West Bengal, India. Experimental soil was a low-lying alluvial with 0.62% organic C, 0.06% total N, 7.9 kg available P/ha, 151.1 kg available K/ha, and pH 6.8.

The field experiment was laid out in a

lentil (cultivar B77) at 30 kg/ha, and linseed (cultivar Neelam) at 10 kg/ha were broadcast 1 d before the harvest of the standing crop of transplanted wet rice (IR36). Three levels of NPK fertilizers (none, recommended dose, and 1.5 times the recommended dose) were broadcast immediately after removal of rice on 28 Oct.

Sources of NPK were urea, single superphosphaste, and muriate of potash. Mustard was harvested 7 Feb; linseed, 20 Feb; and grasspea and lentil, 15 Mar. Lentil gave the maximum seed yield, followed by grasspea. Linseed had the poorest seed yield. All four crops can be established as winter crops after rainfed transplanted rice. The seed and stover yields of the oil seed crops, (mustard and linseed) increased with increased doses of NPK fertilizers. The pulses (grasspea and lentil) did not respond to NPK fertilizers when planted as winter crops (see table).

Effect of different NPK fertilizer levels on seed and stover yields (t/ha) of rainfed winter crops of mustard, grasspea, lentil, and linseed after transplanted wet rice (IR36). West Bengal, India, 1990-92.

NPK fertilizer Rainfed winter crop None dose mended dose Mean

Recommended 1.5 × recom-

Seed Stover Seed Stover Seed Stover Seed Stover

Mustard 0.5 2.0 0.7 3.0 1.5 4.2 0.9 3.2 Grasspea 1.0 4.0 1.1 4.9 0.8 4.4 1.0 4.4 Lentil 1.2 4.7 1.3 4.0 1.2 3.7 1.2 4.1 Linseed 0.4 1.3 0.7 1.6 0.8 1.8 0.6 1.5

Mean 0.8 3.0 1.0 3.4 1.1 3.5 0.9 3.3

Fertilizer (F) Crops (C) F × C

Seed Stover Seed Stover Seed Stover

LSD (0.05) 0.3 ns a 0.4 0.7 0.5 1.2

a ns = not significant.

M. Wijeratne and P. A. N. Chandrasiri, Agricultural Economics Department, Faculty of Agriculture, University of Ruhuna, Kamburupitiya, Sri Lanka

We studied the diffusion pattern of rice varieties developed through a farming systems research and extension (FSR/E) program. Farmers in the southern Sri Lankan district of Matara are confronted with strong soil acidification (pH 3.5-4.0) during the dry season (DS) and excess water during the wet season (WS).

During the technology generation stage of the FSR/E program, rice varieties were screened for tolerance for soil acidification and submergence. Varieties BW272-3 and At85-1 were selected. Both have growth duration of 3 1/2 mo. Based on experimental and on-farm trial results, BW272-3 was introduced in the district in 1988 DS and At85-1 in 1990 DS. See figure for diffusion trends.

BW272-3 had medium tolerance for acidic soils and submerged condition. It exhibited medium resistance to thrips ( Thrips oryzae ) and sheath blight (ShB) ( Corticium sasakii ) and is 95-100 cm tall. The field's microenvironment did not favor the spread of common insect pests and diseases. Unfavorable characteristics included low resistance to brown planthopper ( Nilaparvata lugens Stål), high grain shattering, lower grain weight (21-22 g/l,000 seeds), and white pericarp.

BW272-3 was considered to be a moderately appropriate variety for the target area. Farmers adopted this variety at first, but later responded to the low grain weight and higher farmgate price of red- pericarped varieties. The diffusion curve of BW272-3 shows a declining adoption trend two seasons after it was introduced (see figure).

Red-pericarped At85-1 had medium tolerance for acidic soils, low shattering, and higher grain weight (25-26 g/1000 seeds). It had little tolerance for submerged condition and was susceptible to BPH, thrips, and ShB. Its short height (81-87 cm) made the microenvironment suitable for pests and diseases.

After eight seasons, farmers are again adopting BW272-3, which is moderately


–

Farming systems

–

Diffusion trends of rice varieties in Matara district, southern Sri Lanka. 1988-92 DS and WS. a Many farmers abandoned ricefields due to unusually excessive amounts of water at plant establishment.

appropriate to the local production conditions, although its farmgate price is low. Similarly, At85-1 is gaining popularity, especially in the upper areas of the district where soil acidification is high.

Rice - fish - azolla farming system for low-lying ricefields V. S. Shanmugasundaram and M. Balusamy, Agricultural Research Station (ARS), Bhavanisagar, Tamil Nadu 638451, India

Fish culture in ricefields is a good way for farmers to gain additional protein and income. We studied the economics of the rice - fish - azolla system during 1992 in a low-lying ricefield at ARS.

The soil was sandy loam with pH 7.2, EC 0.1 dS/m, 229 kg available N/ha, 14 kg available P/ha, and 151 kg available K/ha. The experiment was laid out in a randomized block design with

three replications. Calotropis (12.5 t/ha) was incorporated as green leaf manure 10 d before transplanting rice variety ADT 36, which was fertilized with 120-38-38 kg NPK/ha. Azolla microphylla was applied at 2.0 t/ha as fish feed/N fixer. 5 d after transplanting (DT). Different systems were studied (see table).

Field trenches (1 m deep × 1 m wide) were dug for fish shelter. These trenches occupied 10% of the riceland. Catla. rohu, and mrigal were stocked 10 DT at an equal ratio of 3,000 fingerlings/ha. A mixture of banana pseudostem and cow dung (1:1) and rice bran were fed as supplementary feed at the rate of 5% of

average fish body weight. Rice - azolla produced the most grain,

which was at par with rice - fish - azolla - calotropis system (see table). Rice - fish - azolla - calotropis system was more profitable than rice alone, recording an additional income of US$40.70/ha and the highest benefit-cost ratio (1.30) of the systems studied. Rice yield was slightly less under rice -fish system because of the trenches; the fish harvest, however more than compensated for the reduced rice yield.

This study indicates that rice - fish - azolla farming is possible in low-lying ricefields of Tamil Nadu.

Yield, yield attributes, and economics of different rice, azolla, and fish systems. ARS, Bhavanisagar, Tamil Nadu, India, 1992.

Productive Panicle Grains/ Filled 1,000- Grain Fish Net Benefit- System tillers length panicle grains/ grain wt yield yield income cost

(no./m2) (cm) (no.) panicle (no.) (g) (t/ha) (kg/ha) (US$/ha) ratio

Rice Rice - fish Rice - azolla Rice - azolla - fish Rice - azolla - calotropis - fish Rice - azolla (no N) Rice - azolla - calotropis (no N)

LSD (0.05)

417 431 475 482 502 284 364

69.4

20.9 101 21.1 102 21.1 108 21.7 114 21.7 114 18.1 95 19.7 95 ns 8.6

88 92 94 98 99 81 85

8.9

19.7 5.0 81.95 1.21 19.4 4.8 71 84.95 1.21 19.7 5.3 103.90 1.27 19.4 5.0 75 104.70 1.26 20.1 5.2 78 122.65 1.30 18.8 3.9 36.35 1.17 19.0 4.2 50.65 1.15 ns .3


-

-

- - - -

artificially infesting or inoculating plots. To establish DH, rice plants were

Combined effects of pests in farmers' fields:

yield-loss data base in rice field in both experiments was divided maximum tillering stage were inoculated

infested with 4-5 egg masses/m 2 at 3 1992 DS in a farmer’s field in Laguna WAT. Plots were sprayed with 600 ml of Province, Philippines. The farmer’s BB inoculum (10 9 colony-forming units/

methodological outlines of a management practices were used. The ml) at 1, 2, and 3 WAT. Rice plants at

N. P. Castilla, M. O. Mabbayad, A. T. into three blocks that were superimposed with ShB by inserting 5 g of a rice hull-

Barrion, F. A. Elazegui, and S. Savary, lRRI after transplanting (WAT) rice: into the center of each hill. Plots were with the following weed treatments 1 wk grain mixture seeded with the pathogen

Farmers’ management practices can influence the occurrence of insect pests, diseases, and weeds-and the resulting yield losses. Analyzing the combined effects of pests on rice yield is difficult because several pests have to be manipulated and highly variable production situations must be considered. IRRI established a crop-loss data base in 1991 that covers key pests and input factors in irrigated and rainfed lowland rice.

Rice variety PSBRc-4 was planted in 1991 dry season (DS) and C4-137 in

infestation with Echinochloa glabrescens (5 plants/m 2 ), infestation with Monochoria vaginalis (10 plants/m 2 ), and handweeding until rice panicle initiation stage.

Each block had eight microplots consisting of 12 × 12 hills, representing eight randomly assigned pest combinations: bacterial blight (BB), sheath blight (ShB), and yellow stem borer (as deadhearts [DH]); BB and DH; BB and ShB; ShB and DH; ShB only; DH only; BB only; and no pests. High or low pest levels were attained by

Table 1. Lists of pests and explanatory variables.

Pest Injury Acronym Injury component Variable

sprayed daily with water for 1 wk to enhance ShB development.

Pest injuries were assessed at maximum tillering, booting, flowering, and hard dough stages. Prior to statistical analyses, raw data were converted into injury components that best represented the harmful effects of pests (Table 1). Areas under the pest progress curve (AUPPC) for BB, weed infestation above the crop canopy (WA), and weed infestation below the crop canopy (WB) were computed for the period 4-13 WAT.

Multiple regression analyses were performed to describe yield variation using square root transformed pest variables and attainable yield (Ya) as

Scirpophaga incertulas Deadhearts DH Maximum percentage of regressors. Ya, which refers to the yield (yellow stem borer) tillers with DH throughout of the control or protected plot in a

the cropping season- block, was used as an explanatory variable to account for the varying

Xanthomonas campestris Bacterial blight BB Area under BB

Bb production situations within and across experiments: varieties, weeds, fertilizer pv. oryzae severity progress curve

Rhizoctonia solani Sheath blight ShB Maximum ShB severity Sb application, and other factors associated throughout the cropping with farming practices. season In Table 2, equation 1 indicates that

Echinochloa glabrescens Weed infestation WA Area under weeds above Wa (above the crop the crop canopy rating canopy) progress curve

Monochoria vaginalis Weed infestation WB Area under weeds below Wb (below the crop the crop canopy rating canopy) progress curve

all the injuries manipulated in these experiments, except DH, directly reduced yield, and the equation accounted for 65% of the yield variation. Eighty percent of the yield variation was accounted for when Ya was introduced into the analysis, with 73% attributable

Table 2. Multiple regression equations for the experimental data set.

Equation no. Variables Equations a,b R 2b

1 Y = f (Dh, Bb, Sb, Wa, Wb) Y = 7.16 – 0.036 Bb – 0.277 Sb – 0.096 Wa – 0.177 Wb 0.65***

2 Y = f (Ya c , Dh, Bb, Sb, Wa, Wb) Y = 1.00 – 0.911 Ya – 0.200 Dh – 0.219 Sb 0.80***

3 Y = f (Ya, Ya × Dh, Ya × Bb, Ya × Sb, Y = –0.31 + 1.166 Ya – 0.038 Ya × Dh – 0.044 Ya × Sb 0.79***

(0.040*) (0.080**) (0.160***) (0.372***)

(0.728***) (0.026*) (0.041**)

Ya × Wa, Ya × Wb) (0.728***) (0.027*) (0.034*)

a Values in parentheses refer to the partial R 2 of each variable. b *, **, *** = significant at the 5, 1, and .01% levels, respectively. c Ya = atttainable yield.


Research methodology

different N input levels to vary their N content; and different varieties can also be compared.

Data are analyzed using repeated- measures ANOVA. The table shows the format of an ANOVA where the log- transformed number of ShB infection points is analyzed in an experiment with three replications, eight treatments, and three batches. The treatments represent different combinations of inoculum amount and positioning (see figure).

The results indicate that the positioning of inoculum has a significant effect on the number of infection points. Estimates of treatment means are T1: 122 a; T2: 64 b; T3: 82 a; T4: 111 a; T5: 37 b; T6: 147 a; T7: 150 a; and T8: 20 c, where values followed by the same letter are not significantly different according to DMRT

(p<0.05). Further comparison of means shows significantly less infection points when inoculum was placed at the stem level only. A two- to fourfold increase in infection points occurred when the inoculum was placed at the leaf level. Increasing the amount of inoculum from 2.5 to 5.0 g did not significantly increase the number of infection points. The number is significantly lower in the third batch than in the first two batches, suggesting a decline in infection efficiency over time. Spontaneous infections are measured on the control trap plants (T8), which provide a measure of the 'background noise' specific to each experiment.

This methodology can be used to address several driving variables in the rice-ShB pathosystem.

to Ya alone (Equation 2). Equation 3 further shows that increasing pest injuries, specifically ShB and DH, are associated with more than a proportional reduction in yield. Equation 3 demonstrates more generally that the

attainable yield, which represents the

with pest injuries in damage functions injuries in the descriptive damage and environmental factors—interact production levels, interacts with pest farmers' management practices, inputs,

function generated by the two and must be considered in pest experiments. Our data to date show that management. production levels—yield outcome of

A simple methodology for analyzing rice sheath blight (ShB) epidemiologic processes under semicontrolled conditions R. M. Leafio and N. P. Castilla, IRRI; D. B. Lapis, Plant Pathology Department, Univer- sity of the Philippines at Los Baños; and S. Savary, IRRI

We developed a simple and reproducible methodology to study ShB epidemics under semicontrolled environmental conditions. It involves two basic components: 1) an analogue of a standing crop that can be manipulated according to the environmental variables being investigated, and 2) a probe that allows monitoring and quantification of ShB conduciveness in this manipulated environment.

The crop analogue is a quadrat of 3 × 3 hills (see figure). At maximum tillering stage, all hills in the quadrats except the center hill—are inoculated with a rice hull/grain mixture colonized by Rhizoctonia solani Kuhn to serve as source plants. The center hill is removed after inoculation and replaced with a healthy trap plant that was grown in an adjacent, disease-free area. The trap plant serves as a probe. After 3 d of exposure, the trap plant is transferred into a pot. ShB severity is measured, and emerging infection points are counted. The procedure can be used in a series of replications and for several treatments. It can be repeated over time with successive batches of trap plants.

manipulated by covering the quadrat with plastic cages for different amounts of time. Crop density can be varied by planting hills at different spacings. The number and position of ShB lesions in the canopy can be manipulated by varying the amount and positioning of the inoculum. Trap plants can be grown in plots with

Leaf wetness duration can be


Format of a repeated-measures ANOVA for the log-transformed number of infection points per trap plant. The experiment involves 5 replications, 8 treatments, and 3 batches.

Example Source of variation df

df F obs F 0.05 Conservative F 0.05

a

Replication r-1 4 6.23 2.71 2.71 Treatments (T) b t-1 7 12.4 2.36 2.36

Control vs other treatments (U) u-1 1 54.5 4.20 4.20 Among other treatments (V) v- 1 6 5.43 2.44 2.44

T7 vs T1 to T6 (W) w-1 1 7.79 4.20 4.20 Among T1 to T6 (X) x- 1 5 4.96 2.56 2.56

Inoculum positioning (P) P-1 2 11.6 3.34 3.34 Inoculum amount (A) a-1 1 0.00 4.20 4.20 P x A (p-1) (a-1) 2 12.4 3.34 3.34

Error (a) (r-1) (t-1) 28 Batch (B) b-1 2 4.31 3.14 3.99 T x B (t-1) (b-1) 14 1.68 1.85 2.15

(Control vs other treatments) × B (u-1) (b-1) 2 4.90 3.14 3.99 (Among other treatments) × B (v-1) (b-1) 12 1.14 1.90 2.24

(T7 vs T1 to T6) × B (w-1) (b-1) 2 0.01 3.14 3.99 (Among T1 to T6) × B (x-1) (b-1) 10 1.36 1.98 2.36

P × B (p-1) (b-1) 4 2.88 2.51 3.14 A x B (a-1) (b-1) 2 0.74 3.14 3.99 P x A x B (p-1) (a-1) (b-1) 4 3.1 2.51 3.14

Error (b) t(r-1) (b-1) 64

a Based on batch df = 1. The conservative F values are usually considered. b The treatments represent different combinations of amount and positioning of inoculum: T1: 2.5 g at leaf level, T2: 2.5 g at stem level, T3: 2.5 gat stem level and 2.5 gat leaf level, T4: 5.0 g at leaf level. T5: 5.0 gat stem level, T6: 5.0 gat stem level and 5.0 g at leaf level, T7: 5.0 g at stem level and 2.5 g at leaf level, and T8: control.

Design for analyzing rice ShB epidemiologic processes under secontrolled environmental conditions.

Maximum diseased leaf area (DLA): a new parameter for leaf blast (Bl) severity E. Kürschner, Tropeninstitut, Justus Liebig University, Giessen, Germany; and J. M. Bonman and B. A. Estrada, IRRI

B1 disease, caused by Pyricularia grisea Sacc., is evaluated in many experiments. Leaf B1 is often assessed three or more times on the same plot within a season. Epidemiological studies require exact disease assessment, which is labor- intensive. The percentage DLA, a parameter commonly used, can be assessed visually with sufficient precision by a well-trained person using standard diagrams.

We analyzed data sets of two experiments in upland rice with the aim to reduce the labor required for disease assessment. Leaf B1 was assessed visually on five fully developed leaves of 20 tillers/plot for 72 plots.

Leaf Bl progress followed a typical pattern (Fig. 1). Depending on meteorological conditions, initial disease symptoms appeared 15-25 d after seeding (DAS) (on Zadoks’ scale of growth, stage 15, 20/18, 22), followed by a progressive increase in disease severity. The peak in the progress curve occurred at 40-50 DAS. A steep decrease in severity was

1. Typical pattern of leaf BI progress.

2. Relation of AUDPC and values of maximum DLA for leaf BI.

observed thereafter and an initial low was reached about 70-80 DAS. This pattern was confirmed during several years of field experiments in the Philippines.

Fertilizer application and various upland cultivars (UPLRi-5, C22, Kinandang Patong, and IR47686-6-2-2-1) showed a synchronous disease progress (Fig. 1). A close linear relationship ( r 2 = 0.99, n = 72. based on data range of 0-60% DLA) between the maximum DLA and area under the disease progress curve (AUDPC) was observed (Fig. 2). Comparing treatment means for AUDPC and for maximum DLA yielded the same result.

Using the maximum DLA as a parameter for leaf B1 severity proved to be a reliable and practical method in

several field experiments. The sensitive response of the disease progress to meteorological conditions—especially at the early vegetative stage when rice plants are extremely susceptible to B1— requires continuous monitoring of actual disease intensity in control plots. This procedure enables the researcher to predict the time of maximum disease severity.

Weather conditions and cultivar resistance can alter leaf B1 progress. Comparing data from various sites and rice cultures using maximum DLA needs further investigation. Researchers are encouraged to test the parameter under their specific site conditions.


News about research collaboration IRRI-CIMMYT on Rice-Wheat Collaboration Researchers in Asia's four-country Rice- Wheat Collaboration are ready to share new technologies with farmers. Advanced lines of rice and wheat are available for farmers in India and Bangladesh. New cultivars have also been identified in Bangladesh for planting in the productive jute - transplanted rice - minimum tillage wheat sequence.

Researchers in Pakistan and Nepal are passing on technology for direct seeding of wheat, while scientists in India are recommending gypsum amendment to brackish irrigation water. A new wheat- seed treatment and surface seeding technique have been adapted to conditions in Nepal and Bangladesh.

IRRI and CIMMYT are working in the Rice-Wheat Collaboration with the four national agricultural research systems. IRRI's coordinating scientist for rice-wheat, T. Woodhead, says that in future research, the group will develop technologies for rainfed as well as irrigated rice-wheat farming systems.

Vietnamese rice farmers quickly adopt "water seeding" Farmers in the flood-prone Mekong Delta of Vietnam are turning to water seeding of rice. The practice reduces problems of weeds and uneven field levels. Just 4 yr after the practice was introduced, farmers are using water seeding on about 300,000 ha of rice.

With water seeding, farmers place pregerminated rice seeds into 50 cm of standing water, wait 5 d, then lower the water level to 10 cm. The technique

German Government and Asian Development Bank help IRRI launch Asian Rice Biotechnology Network The Asian Rice Biotechnology Network is a major new initiative of IRRI to transfer advances in cellular and molecular genetics of rice to national agricultural research systems (NARS). The German Government and the Asian Development Bank are jointly funding the first three years of network operation, according to K. Lampe, IRRI director general. The German funding is provided by the Federal Ministry for Economic Cooperation (BMZ) through the German Agency for Technical Cooperation (GTZ) .

IRRI biotechnology programs, a biotechnology training laboratory at IRRI, and equipment and supplies for NARS laboratories, leading to biotechnology products to be shared with NARS in Asia.

This will provide for joint NARS-

should not be confused with wet seeding, which involves broadcasting pregerminated seed on puddled, water- drained soil.

The disadvantage with water seeding is the need to control fish and crustaceans that like to feed on the germinating seeds and young seedlings.

Scientists of the Cuu Long Rice Research Institute and the University of Agriculture and Forestry, Vietnam, and IRRI are studying water seeding to learn the best ways to monitor water levels, temperatures, and other conditions.

Initial members of the network are China, India, Indonesia, Philippines, and Thailand. J. Bennett, senior molecular biologist at IRRI, is network coordinator, and R. Nelson, associate plant pathologist, is deputy coordinator.

from the network in its first years: 1) a core of scientists from different disciplines will be trained in molecular marker-aided selection of DNA finger printing for eventual production of plant lines with more durable resistance to rice blast, tungro virus, and bacterial blight; 2) refined rice transformation procedures will be developed for direct introduction of novel genes for resistance to biotic stresses, such as insects, fungi, and viruses; and 3) data bases will be compiled on molecular markers and tagged genes, and combined with computer software, will be used to locate the numerous genes that condition quantitative traits such as blast resistance and drought tolerance.

Bennett expects three major results


Announcements Rice Dateline

1-3 Sep IRRI-EPA Methane Project Annual Work Plan Meeting, IRRI .................................................................. H.U. Neue, IRRI

6-22 Sep Interregional Research Program on Methane Emission from Ricefields Training Course, IRRI .................................................................. H.U. Neue, IRRI

8-10 Sep Outposted Staff Meeting, IRRI ...................................................................... F.A. Bernardo/

G.L. Denning, IRRI

27 Sep-1 Oct International Workshop on Crop-Animal Interactions, Khon Kaen, Thailand ...................................... V.R. Carangal, IRRI

27 Sep-15 Oct Effective Irrigation Management, Southampton, United Kingdom ..................... Course Administrator

Effective Irrigation Management Short Courses

Institute of Irrigation Studies The University, Southampton

S09 5NH, UK

28 Sep-15 Oct Lowland Development Short Course, Delft, The Netherlands .............................................. The Registrar

International Institute for Infrastructure, Hydraulic and

Environmental Engineering Delft, The Netherlands

11-15 Oct Sheath Blight Disease Management Workshop, Beijing, China .................................... T. W. Mew, IRRI

1-4 NOV International Conference on the Current Status and Future Directions of Rice- Related Training Programs in Asia, Bangkok, Thailand ........................................... E.L. Matheny, IRRI

8-11 NOV International Workshop on Rice Tungro Disease Management, Malaysia ............................................................ K.L. Heong, IRRI

7-10 Dec IRRI-ICRISAT Planning Meeting Asian Institute of Technology, Bangkok, Thailand .............................................. R. Zeigler, IRRI

Postdoctoral research fellowship positions at IRRI

The International Rice Research institute invites applicants for postdoctoral research fellow position in the following fields: Molecular biology. Improvement of rice breeding efficiency through the characterization of genes resistant to rice bacterial leaf blight and blast. The work involves tagging genes with molecular markers, physical mapping through construction of contigs and the eventual cloning and characterizing of the genes, and elucidating the defense mechanism of the rice plant to bacterial and fungal infections.

A candidate should have a Ph D degree in molecular genetics or relevant fields with expertise in recombinant DNA technology, molecular analysis of complex genomes, and experience in handling cosmid, P1, or YAC clones. Knowledge of plant system is preferred but not required. The three-year position is available immediately and will remain open until a qualified candidate is selected.

Send curriculum vitae, university transcripts, and three letters of recommendation to N. Huang, Plant Breeding, Genetics, and Biochemistry Division, IRRI.

Plant pathology. Investigation of gene deployment strategies to attain durable resistance to rice diseases. The goal of the work will be to determine the population-level mechanisms that influence the response of plant pathogen populations to deployment of host plant resistance. Research will entail field and greenhouse studies, as well as conceptual and mathematical modeling. A candidate should have a strong background in plant pathology with training in population genetics, ecological genetics, quantitative epidemiology, or a related subdiscipline. English fluency is highly desirable. The position is funded by the World Bank/


United Nations Development Programme biological control of rice insect pests. Who are the outstanding (UNDP). A candidate must have a Ph D in young women in rice science?

Send curriculum vitae, university entomology or ecology and three years transcripts, and three letters of experience in ecological research. recommendation to T. W. Mew, Plant preferably community ecology. The Pathology Division, IRRI. project is funded by UNDP.

Send curriculum vitae, university Entomology. Carrying out field transcripts, and three letters of ecological studies to determine the role of recommendation to K. L. Heong. habitats associated with rice in natural Entomology Division, IRRI.

Women often do most of the work in growing and harvesting rice, but they are insufficiently represented as scientists in rice research.

IRRI is leading the way in improving this situation by offering the Outstanding Young Women in Rice Science awards. Established in 1990, these recognitions

Climate Change and Rice Papers on production and emission of encourage greater participation by Symposium trace gases by rice soils and the effects of women in rice research and promote their

UV-B, CO 2 , and temperature on rice will professional improvement. An international symposium on climate change and rice will be held at IRRI on 14-18 Mar 1994. The meeting will review the broad issues of global climate change and its effect on agriculture. The symposium will also provide a forum to sum- marize research on the specific impact of climate change on rice and rice ecosystems.

be presented by 27 invited speakers. Other participants are encouraged to present posters on these topics.

For details, contact

K. T. Ingram, Climate Change and Rice Symposium, IRRI.

E-mail: lN%“k.ingram@ CGNET.COM”.

The awards are made every two years during the International Rice Research Conference (IRRC). Each winner receives a recognition plaque and a travel grant to attend IRRC, where she presents a paper on her research. DANIDA, the Danish International Development Agency, is funding the 1994 program.

The awards are for women who are 40 years of age or younger (born on 1 Jan 1954 or later) and actively conducting

IRRI 1993 courses

- group training research in any endeavor of rice science

in a public or private institution located in the five regions of the developing world's

The IRRI Training Center offers a variety unless otherwise noted. For information rice-producing areas. Recipients are of courses on rice-related subjects. about a course, contact the Head. selected by regions: Africa, South Asia, Courses are held at IRRI headquarters Training Center, IRRI. West Asia, Southeast Asia, and Latin

America and the Caribbean. Awards are made without regard to race, color,

Date Course Trainees religion, national origin, or political (no.) persuasion of the nominees.

Each nomination must be submitted 4 Oct-5 Nov Rice Seed Health 8 by the head of the employing research 4 Oct-26 Nov Integrated Pest Management 25 institution or agency. It must be in 11 Oct-3 Dec Rice Production Research, Thailand a 25 English and include a description of the

15-26 Nov Research Management a 15 accomplishments (not to exceed 15-26 Nov Gender Analysis a 25 individual's research work and previous

a Speclal project-fundcd courses.

Rice literature update reprint US$O.20 for each page or part of a page copied, plus postage. Checks or money orders should be payable to Library and service

Photocopies of items listed in the Rice

(not to exceed 40 pages) are supplied free E-mail: IN%“postmaster@ Service. Reprints of original documents IRRI.

Library and Documentation Service, lRRI Library and Documentation Address requests to literuture updute are available from the

Documentation Service, IRRI.

Rice scientists elsewhere are charged to rice scientists of developing countries. 1RRI.CGNET.COM”

1,000 words).

accompanied by Each nomination must be

two of the individual's published papers or technical reports issued between 1989 and 1992, a curriculum vitae or biodata statement and a certification of birthdate (with English translation if needed), five copies of a current photograph, black-and-white or color, suitable for publication (minimum size: 2 × 2 inches or 5 × 5 cm), and


recommendations from three references to support the nomination.

The selection committee appointed by the IRRI director general will evaluate the nominations and choose the 1994 awardees. Their selections will be based on the originality and relevance of the nominee’s rice research and the scientifically rigorous manner in which it has been conducted. The decisions of the committee are final, and no award will be made for any region in which the nominees fail to demonstrate excellence in rice research.

All nominations and supporting materials must be received by IRRI by

UNE 1994 short courses The University of New England in Armidale, New South Wales, Australia, is accepting applications for its 1994 International Short Course Program for agricultural and resource economics. Courses offered include Management of Agricultural Research, Economics of Resource and Environmental Management, Computers in Development Planning, and Planning for Sustainable Rural Development.

For further information, contact

J. Brian Hardaker Department of Agricultural Economics

and Business Management University of New England Armidale NSW 2351, Australia Tel: (6167) 73 2232/73 2205 Fax: (6167) 71 1531 Telex: AA 166050 E-mail: Brian.Hardaker@

UNE.Edu.au

Call for news

Individuals, institutions, and organizations are invited to tell readers about upcoming events in rice research or related fields in the Rice Dateline. Send announcements to

The Editor International Rice Research Notes IRRI

5:00 p.m., 1 Feb 1994. Incomplete submissions are not acceptable. Nominations should be sent to

Chairperson Outstanding Young Women in Rice

c/o Information Center IRRI

Science Award

All nominations will be acknowledged when received, will become the property of IRRI, and will not be returned.

For further information about the program and procedures, send a letter to the address above or fax (63-2) 818-2087

Temperate rice conference

A rice technical conference, Temperate Rice-Achievements and Potential, will be held 21-24 Feb 1994, at Yanco Agricultural Institute, Yanco, New South Wales, Australia. The McCaughey Memorial Institute is sponsoring the conference. Themes are breeding and genetics, quality, storage and processing, rice agronomy and management, crop protection, economics and marketing, environment and sustainability, and extension and education.

For more information, contact

Conference Convenor Temperate Rice—Achievements and

Wet seeded rice workshop NSW Agriculture, P.O. Box 1490 IRRI will host a workshop on Constraints, Griffith NSW 2680, Australia

Potential

Opportunities, and Innovations for Wet

Bangkok, Thailand. Discussion topics will Revised Journal of production include environmental characterization, agriculture introduced by germplasm evaluation, input use efficiency (water, nutrients, labor), pest management (weeds, diseases, insects, snails), and social and environmental

The Journal of production agriculture

concerning agricultural research for implications. now offers the most current information

Workshop goals are to exchange practicing efficient agriculture. The information, assess technology for journal’s new format makes it easier for different environments, determine the professional to read and apply today’s research priorities, and develop a work research. Each summary poses a research plan. question and gives literature summary,

Scientists actively involved in wet study description, any recommendations, seeded rice research are encouraged to and most importantly, answers one to attend the workshop and to present papers. three applied questions. Paper topics should deal with ongoing The Journal of production agriculture research and must contain primary data is published quarterly by the American and results that are relevant to a diverse Society of Agronomy (ASA), the Crop audience of rice scientists. Review papers Science Society of America (CSSA), and on country-level assessment of the extent the Soil Science Society of America of wet seeding, problems, and policies will (SSSA) in cooperation with other also be considered. Abstracts must be professional societies. received by 15 Nov 1993. Scientists For more information, contact D.G. whose abstracts are accepted must submit Westfall, editor, ASA, CSSA, SSSA, their full length papers by 3 Jan 1994. Headquarters Office, 677 South Segoe

workshop details to K. Moody, APPA

Seeded Rice on 24-27 May 1994 in

ASA, CSSA, and SSSA

Send abstracts and requests for Road, Madison, WI 53711-1086, USA.

Division, IRRI.


Rice conference for Latin America and the Caribbean The 9th International Rice Conference for Latin America and the Caribbean and the 5th National Rice Research Meeting of Brazil will be held in Goiania, Goias, on 21-25 Mar 1994. They are jointly sponsored by the International Network for Genetic Evaluation of Rice (INGER) for Latin America and the National Research Center for Rice and Beans (EMBRAPA/CNPAF) of Brazil.

The meetings are to analyze alterna- tives for increasing productivity of rice in the region. Topics to be discussed will include the genetic improvement and commercial achievement of the biological yield potential, cropping systems for the efficient use of available resources, diversification of uses and markets to increase consumption, and organization of research to integrate public and private resources.

For more details, contact

Beatriz de Silveira Pinheiro EMBRAPA/CNPAF Caixa Postal 179 7400 Goiania, GO, Brazil Tel: (5562) 261-3022 Fax: (5562) 261-3880.

Federico Cuevas-Pérez c/o CIAT Apartado Aéreo 67 13 Cali, Colombia Tel: (5723) 6750.50 x396 Fax: (5723) 647243

New publication IRRI address

Biotechnology: enhancing research on tropical crops in Africa. ed. by G. Thottappilly, L. M. Monti, D. R. Mohan Raj, and A. W. Moore.

To order, contact the Technical Centre for Agricultural and Rural Cooperation, Postbus 380,61700 AJ Wageningen. The Netherlands.

Tel: (31) 8380 60400 Telex: (44) 30169 CTA NL Fax: (3 1) 8380 24262.

International Rice Research Institute P.O. Box 933 Manila 1099 Philippines Tel: (63-2) 818-1926 Fax: (63-2) 818-2087 Telex: (ITT) 40890 RICE PM E-mail: IN%"postmaster@

1RRI.CGNET.COM"

Erratum Sensitivity to gibberellic acid (GA,) of seedlings and endosperms of rice lines with different genes for height, by He Zuhua et al, 18(2) (Jun 1993), 7.

In the figure, the label Mutant D for the lower photo should be Mutant T.


Instructions for contributors

NOTES

General criteria. Scientific notes submitted to the IRRN for possible publication must • be original work, • have international or pan- national relevance, • be conducted during the immediate past three years or be work in progress, • have rice environment relevance, • advance rice knowledge, • use appropriate research design and data collection methodology, • report pertinent, adequate data, • apply appropriate statistical analysis, and • reach supportable conclu- sions.

Routine research. Reports of screening trials of varieties, fertilizer, cropping methods, and other routine observations using standard methodologies to establish local recommendations are not accepted. Examples are single-season, single-trial field experiments. All field trials should be repeated across more than one season, in multiple seasons, or in more than one location as appropriate. All experiments should include replications and an internationally known check or control treatment.

Multiple submissions. Normally, only one report for a single experiment will be accepted. Two or more items about the same work submitted at the same time wiII be returned for merging. Submit- ting at different times multiple notes from the same experiment is highly inappropriate. Detection will result in the rejection of all submissions on that research.

IRRN categories. Specify the category in which the note being submitted should appear. Write the category in the upper right-hand corner of the first page of the note.

GERMPLASM IMPROVEMENT genetic resources genetics breeding methods yield potential grain quality pest resistance

diseases insects other pests

stress tolerance drought excess water adverse temperature adverse soils other stresses

integrated germplasm improvement

irrigated rainfed lowland upland deepwater tidal wetlands

seed technology

CROP AND RESOURCE MANAGEMENT

soils soil microbiology physiology and plant nutrition fertilizer management

inorganic sources organic sources

crop management integrated pest management

diseases insects weeds other pests

water management farming systems farm machinery postharvest technology economic analysis

ENVIRONMENT SOCIOECONOMIC IMPACT EDUCATION AND COMMUNI-

CATION RESEARCH METHODOLOGY

Manuscript preparation. Arrange the note as a brief statement of research objectives, a short description of project design, and a succinct discussion of results. Relate results to the objectives. Do not include abstracts. Do not cite references or include a bibliog- raphy. Restrain acknowledg- ments.

Manuscripts must be in English. Limit each note to no more than two pages of double- spaced typewritten text. Submit the original manuscript and a duplicate, each with a clear copy of all tables and figures. Authors should retain a copy of the note and of all tables and figures.

Apply these rules, as appropriate, in the note: • Specify the rice production ecosystems as irrigated, rainfed lowland, upland, deepwater, and tidal wetlands. • lndicate the type of rice culture (transplanted, wet seeded. dry seeded). • If local terms for seasons are used, define them by characteristic weather (wet season, dry season, monsoon) and by months. • Use standard, internationally recognized terms to describe rice plant parts, growth stages, and management practices. Do not use local names. • Provide genetic background for new varieties or breeding Iines. • For soil nutrient studies, include a standard soil profile description, classification, and relevant soil properties. • Provide scientific names for diseases, insects, weeds, and crop plants. Do not use common names or local names alone. • Quantify survey data, such as infection percentage, degree of severity, and sampling base. • When evaluating susceptibility, resistance, and tolerance, report the actual quantification

of damage due to stress, which was used to assess level or incidence. Specify the mea- surements used. • Use generic names, not trade names, for all chemicals. • Use international measure- ments. Do not use local units of measure. Express yield data in metric tons per hectare (t/ha) for field studies and in grams per pot (g/pot) for small-scale studies. • Express all economic data in terms of the US$. Do not use local monetary units. Economic information should be presented at the exchange rate US$:local currency at the time data were collected. • When using acronyms or abbreviations, write the name in full on first mention, followed by the acronym or abbreviation in parentheses. Use the abbreviation thereafter. • Define any nonstandard abbreviations or symbols used in tables or figures in a footnote, caption, or legend.

Tables and figures. Each note can have no more than two tables and/or figures (graphs, illustrations, or photos). All tables and figures must be referred to in the text; they should be grouped at the end of the note, each on a separate page. Tables and figures must have clear titles that adequately explain the contents.

Review of notes. The IRRN editor will send an acknowledg- ment card when a note is received. An IRRI scientist, selected by the editor, reviews each note. Reviewer names are not disclosed. Depending on the reviewer’s report, a note will be accepted for publication, rejected, or returned to the author(s) for revision.

(continued on back cover)

international rice research notes vol.18 no.3

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