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analysis.

environment (irrigated, rainfed lowland, upland, deepwater, tidal wetlands).

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Specify the rice production

Specify the type of rice culture (transplanted, wet seeded, dry seeded). Specify seasons by characteristic weather (wet season, dry season, monsoon) and by months. Do not use local terms for seasons or, if used, define them. Use standard, internationally recognized terms to describe rice plant parts, growth stages, environments, management practices, etc. Do not use local names. Provide genetic background for new varieties or breeding lines. For soil nutrient studies, be sure to include a standard soil profile description, classification, and relevant soil properties.

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Categories of research published

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

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

integrated germplasm improvement

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 COMMUNICATION

RESEARCH METHODOLOGY

CONTENTS GERMPLASM IMPROVEMENT

Genetics 5 Inheritance of hybrid weakness in indica/japonica rice crosses

Breeding methods 5 Inheritance of a low-tillering plant type in rice

Grain qualify 6 Test of three rice grain quality characteristics 7 Grain quality of F 1 hybrids between wide-compatible japonica rice

8 Phenological and quality aspects of grains of rice O. sativa L.

Pest resistance—diseases 8 Reexamination of linkage relationships between blast (B1) resistance

02428 and indica varieties

genes Pi-i and Pi-z using near-isogenic lines (NILS) of rice

Pest resistance—insects 9 Identification of a new Asian rice gall midge (GM) population in

10 Brown planthopper (BPH)-resistant varieties developed at Moncompu, Bhandara District, Maharashtra, India, and highly resistant genotypes

Kerala

Pest resistance—other pests 10 Upland rice cultivars resistant to parasitic weed

Striga hermonthica

Stress tolerance—drought 11 Performance of shallow water rice for drought tolerance

Stress tolerance—excess water 11 Screening of rice germplasm against natural flooding in Cambodia

Stress tolerance—adverse temperature 12 Evaluation of indica/japonica crosses during boro season in West Bengal

Integrated germplasm improvement—irrigated 13 KAU170, a promising short-duration rice variety resistant to brown

13 Performance of Mukthi (CTH1) in coastal Karnataka, India 13 Rernya—a new brown planthopper (BPH)-resistant, medium-duration

14 RCPL 1-1C, a cold-tolerant rice for high-altitude areas of Meghalaya,

planthopper (BPH)

variety from Kerala

India

CROP AND RESOURCE MANAGEMENT

Fertilizer management—inorganic 15 Phosphorus effects on rice yield under different moisture regimes during

wet season in West Bengal, India

Fertilizer management—organic 15 Intercropping green manure (GM) crops with dry season irrigated rice 16 Effect of continuous application of organic manure on the physical

properties of soil in a rice - wheat cropping system

Crop management 17 Farmer-participatory rainfed lowland rice varietal testing in Cambodia 18 Effects of submergence timing and application of azospirillum and K on

18 Planting rainfed winter crops in rice fallows under different N and tillage direct seeded rice

treatments

Inregrated pest management—diseases 19 A trap plant method to predict the Occurrence of rice blast (B1) 20 Tungro viruses in volunteer rice plants

Integrated pest management—insects 20 Sweep net efficiency as affected by insect stage and sex, pipunculid

parasitism, and rice stage

Integrated pest management—oher pests 21 Rat damage in ricefields under dry field conditions in Madhya Pradesh

(MP), India

ANNOUNCEMENTS

21 Call for news 21 New publication 21 Rice dateline 22 IRRI group training courses for remainder of 1992

NEWS ABOUT RESEARCH COLLABORATION

22 IRRI foresees 21st century rice shortage without more rice research 22 A BPH-resistant glutinous rice for Lao PDR 22 Seven countries adopted 15 IRRI varieties in 1991 22 IRRI, Iranian university sign technical cooperation pact 23 Turkey-IRRI collaboration 23 Calcutta University uses INGER-developed biochemical screening

method

ERRATA

Aikawa 1. This spontaneous mutant was discovered by a Japanese farmer in 1980. Restricted tillering, long and thick culms, and dense panicles are the mutant-type characters that distinguish the variety’s plant type.

We investigated the inheritance mode

GERMPLASM IMPROVEMENT Genetics Inheritance of hybrid weakness in indica/japonica rice crosses

K. Ise, National Agriculture Research Center (NARC), Tsukuba, Ibaraki; K. Sekizawa, National Institute of Agrobiological Resources (MAR), Tsukuba, Ibaraki; and H. Sato, Plant Laboratory, Kirin Brewery Co., Ltd., Kitsuregawa, Tochigi, Japan

We investigated the inheritance of hybrid weakness occurring in F 2 , F 3 , and subsequent generations in remote crosses of rice.

The F 1 plants of indica (IR24, CR44, Milyang 23, and Suweon 258) and japonica varieties from Japan showed vigorous growth and partial sterility.

The weak segregants in F 2 were slightly yellow at the seedling stage. Fresh weight of their aboveground phytomass 60 d after transplanting averaged about one-tenth as much as that of normal plants. Some of them died before heading. Mature plants were stunted and had only a few short panicles. Numbers of normal and weak plants observed in six F 2 populations are given in Table 1. The relative frequency of weak segregants was 2.2 to 7.5%, which fit the expected frequency of 6.3% under a duplicate recessive gene system.

In the F 3 lines derived from randomly sampled F 2 plants of Toyonishiki/ Milyang 23, 27 lines produced all normal plants, 11 lines segregated 15 normal to 1 weak, 14 lines segregated 3 normal to 1 weak, and 2 lines produced all weak plants. This segregation pattern gave a good fit to the expected 7:4:41 (c2 = 1.5238, 0.60 < P < 0.70).

The BC 1 F 1 plants were all normal. The segregation of BC 1 F 2 lines gave a good fit to the expected 2 (all normal):1 (segregating 15:l) : 1 (segregating 3:l) ratio in all crosses (Table 2).

A duplicate recessive gene system in which double recessive homozygotes express weakness can be adapted to these segregation patterns. This is a new

Table 1. Segregation for hybrid weakness in F 2 populations.

Plants (no.) Weak P Cross combination plants (15:l) (df=l)

Normal Weak Total (%)

Reimei/IR24 128 4 132 3.03 2.3354 0.10-0.20 CR44/Reimei 319 26 345 7.54 0.9741 0.30-0.40 Akihikari/Milyang 23 131 3 134 2.22 3.6796 0.05-0.10 Toyonishiki/Milyang 23 132 8 140 5.71 0.0686 0.75-0.80 Milyang 23/IG-15 a 631 35 666 5.26 1.1247 0.25-0.30 Reimei/Suweon 258 129 3 132 2.27 3.5636 0.05-0.10

a IG-15 = Ishiokamochi 15.

Table 2. Segregation for hybrid weakness in BC 1 F 1 populations and BC 1 F 2 lines.

Plants in BC 1 F 1 BC 1 F 2 lines (no.) with populations (no.) the ratio (normal:weak) P

Cross combination a (2:l:l) (df=2) Normal Weak 1:0 15:l 3:l

Reimei/M23/M23 Reimei/M23/Reimei M23/Akihikari/M23 M23/Toyonishiki/M23 S258/Reimei/S258 Reirnei/S258/Reimei Reimei/IR24/IR24 Reimei/IR24/Reimei CR44/Reimei/CR44

28 92 18 48 34 40 20 34 46

0 0 0 0 0 0 0 0 0

16 7 5 53 19 20

8 6 4 25 10 13 21 6 7 22 9 9 13 4 3 17 10 7 22 15 9

0.8571 2.1522 0.6667 0.4583 1.9412 0.4000 1.9000 0.5294 1.6522

0.60-0.70 0.30-0.40 0.70-0.75 0.75-0.80 0.30-0.40 0.80-0.90 0.30-0.40 0.75-0.80 0.40-0.50

a M23 = Milyang 23, S258 = Suweon 258.

genic system for hybrid weakness in would eliminate desirable recombinants remote crosses of rice. Hybrid breakdown and distort segregations of genes in in F 2 and later inbred generations due to breeding programs using indica-japonica hybrid weakness and partial sterility hybridization.

Breeding methods Inheritance of a low-tillering plant type in rice

K. Ise, National Agriculture Research Center (NARC), Tsukuba, Ibaraki 305, Japan

A major gene controlling the low tillering of the plant type using a cross between trait was found in Japanese variety Aikawa 1 and Chiyonishiki, which is

Table 1. Characteristics of plant type components of Aikawa 1, Chiyonishiki, and their F 1 . a

Days to Culm Panicles Diameter Panicle characters Weight Variety heading length pe plant of main of a

(no.) (cm) (no.) culm b Panicle Spike- Seed Primary Secondary brown (mm) length lets fertility branches branches rice

(cm) (no.) (%) (no.) (no.) grain (mg)

Aikawa 1 98.0 93.6 4.9 10.00 21.7 221.4 87.4 16.3 45.4 23.3 Chiyonishiki 103.0 76.5 11.8 5.37 18.3 97.1 96.9 9.5 16.3 22.4

96.0 91.4 8.4 7.92 20.7 182.6 91.0 14.0 36.8 23.1 (96) (108) (101) (103) (104) (115) (99) (109) (119) (101)

F 1

a Figures in parentheses are percentages of F 1 compared with the midparent. b Measured at the central part of the fifth internode.

IRRN 17:4 (August 1992) 5

Table 2. Phenotypic correlations among plant type characters of the Aikawa 1/Chiyonishiki F 3 lines (n = 69).

Culm Panicle Panicles Total Panicle Harvest Single Spikelets Panicle Days to Character a length length per plant weight weight index panicle per panicle density heading

(CL) (PL) (NP) (TW) (PW) (HI) (SPW) (NS) (PD) (NHD) weight

PL NP TW PW HI SPW NS PD NHD PTI

0.442 –0.891 –0.378 –0.348

0.089 0.903 0.869 0.884 0.624 0.858

–0.446 0.118 0.256 0.500 0.614 0.624 0.507 0.177 0.467

0.636 0.567 0.960

–0.209 –0.081 0.194 –0.914 –0.335 –0.248 0.308 –0.875 –0.341 –0.244 0.348 0.952 –0.887 –0.398 –0.316 0.291 0.939 0.990 –0.452 –0.010 –0.046 –0.093 0.513 0.467 0.488 –0.910 –0.503 –0.442 0.218 0.949 0.908 0.913 0.434

a PTI (plant type index) = SPW/NP × 100. PD = NS/PL. Pr[lrl > 0.237] = 0.05, Pr[lrl > 0.3081 = 0.01, df = 67.

high-tillering and short-statured. F 1 , F 2 , the F 2 and F 3 plants. Thus F 2 segregated and F 3 plants were transplanted. F 1 plants into 358:112 (mutant:normal), and gave a had intermediate plant type (Table 1). good fit to 3:1 ratio ( c 2 = 0.3433,0.50 < Mutant-type characters showed P < 0.60). incomplete dominance in the F 1 . Each The F 3 lines derived from randomly character had a segregation ratio of 3 sampled F 2 plants segregated into mutant:1 normal in the F 2 . These mutant 23:31:15 (mutant:segregating:normal), characters were completely associated in and gave a good fit to a 1:2: 1 ratio ( c 2 =

2.913,0.20 < P < 0.30). Several plant type characters, such as panicles per plant, spikelets per panicle, and culm length, showed either highly positive or negative correlations in the F 3 lines (Table 2). A single semidominant gene controls the low tillering trait, and this gene has pleiotropic effects on culm length and thickness, and panicle density.

Aikawa 1 and the true breeding F 3 lines of the mutant type had long culms that were very thick and sturdy and therefore resistant to lodging. These plants showed high seed fertility, erect leaf habit, and normal plant and grain development. The presence of these traits distinguishes this source of a major genic low tillering habit from others previously reported.

We are conducting yield trials under direct seeded conditions using several pairs of lines that are near isogenic except for the low tillering trait.

Grain quality Correlation coefficients among three quality characteristics by group. a

Test of three rice grain quality characteristics

Zhang Xian-guang and Huang Yong-kai, Food Crops Research Institute, Hubei Academy of Agricultural Sciences, Wuhan 430064, China

We randomly chose 86 rice varieties of different origins from the International Rice Germplasm Center of IRRI and Hubei Province and used standard tests to determine amylose content (AC), gelatinization temperature (GT), and gel consistency (GC).

Distribution and performance of rice grain quality characteristics were country or region specific to some extent (see figure). In general, Japanese rice had low AC, low GT, and soft GC; most Korean rice had low AC and low to intermediate GT; IRRI (Philippine) varieties usually had high AC, low GT, and varying GC; Chinese varieties had varied characteristics across the four subgroups.

Samples from Japan, Korea, and central China had the most acceptable characteristics for japonica varieties: low to medium AC, low to intermediate GT,

Group or subgroup Samples b

(no.)

IRRI n 1 = 22 n 2 = 23

Japan n 1 = 10 n 2 = 11

Korea n 1 = 9 n 2 = 10

China n 1 = 39 n 2 = 42

Northern China n 1 = 10

Southern China n 1 = 9 n 2 = 10

Central China n 1 = 11 n 2 = 13

Taiwan n = 9

Total n 1 = 80 n 2 = 86

Correlation

AC—GT AC—GC GT—GC Examples

IR8, IR20, –0.26 –0.45* –0.15 IR36, IR54 –0.27 –0.39 –0.1

Norin 9, 0 –0.61 * 0 Akage, Kuromochi 0 –0.59* 0

Suk Na, Banto 0.53 –0.69* –0.24 Kanon 0.25 –0.80** –0.02

–0.68** –0.85** 0.59** –0.24 –0.85** 0.32*

Ta Ma Gu Chuan Nien –0.97** –0.92** 0.82**

Fu Lu Tsan, –0.02 –0.10 –0.87** Chiu Erh Ai, Chen Ma Ai 0.79** –0.83** –0.95**

Keng 73, 0.24 –0.68* –0.69* E Yi 105, Yu Dao 0.78** –0.87** –0.78**

Chianan 2, Liu Chow –0.73* –0.78* 0.64

–0.12 –0.53** 0.26* –0.11 –0.59** 0.2 1

a *,** = significant difference at 5% and 1% levels. b n 2 = n 1 + waxy varieties if present.

and soft to medium GC, the result of Some associations existed among the selecting to meet the preferences of three characteristics though they differed consumers. with rice group and if waxy varieties

6 IRRN 17:4 (August 1992)

were included (see table). Waxy and very low AC varieties always had soft GC, clearly indicated by the significantly negative correlation. The relationships between AC and GT, and GT and GC were not as perfect as that between AC and GC.

Grain quality of F 1 hybrids between wide-compatible japonica rice 02428 and indica varieties

Y. Shen, Q. Cai, and M. Gao, Institute of Nuclear-Agricultural Sciences (INAS), Zhejiang Agricultural University, Hangzhou 310029, China

We evaluated the grain quality of intersubspecies rice hybrids from the cross between six maternal indica varieties and wide-compatible paternal japonica rice 02428. Physicochemical characteristics were analyzed using standard methods.

The 1,000-grain weight of the six hybrids was 23.4-26.0 g, all within the range of their parents, except for Milyang

Physicochemical characters of indica-japonica rice hybrids at INAS, Hangzhou, China.

1000- Chalkiness Amylose Gel Alkali Variety or grain Hulling Length L/W % Score content consistency a digestion a

combination weight (g) (%) (mm) ratio (0-9) a (%) (score 1-9) (1-7)

Shanyou 10 (check) 26.7 80.2 55 2.3 23.0 9 28.2 5 5 02428 24.2 79.7 44 1.6 50.0 9 18.5 5 3 IR1361 21.8 78.7 58 2.6 0.0 0 22.9 5 7 IR1361/02428 25.2 81.7 52 2.1 8.5 1 22.0 5 4 IR1362 22.3 80.6 51 2.1 0.5 0 21.9 9 7 IR1362/02428 23.4 81.6 51 2.0 5.5 1 17.2 1 4 IR1371 20.8 79.7 50 2.2 3.0 1 20.7 1 6 IR1371/02428 24.3 81.7 49 1.9 28.0 9 22.1 5 4 Milyang 46 25.6 80.4 54 2.3 2.0 1 21.3 9 6 Milyang 46/02428 26.0 82.4 51 2.0 11.5 5 16.9 9 5 Minghui 63 26.2 79.0 67 3.1 0.0 0 6.1 9 6 Minghui 63/02428 25.3 79.7 59 2.5 23.5 9 21.5 3 4 T64-7 22.5 78.5 67 3.5 12.5 5 28.4 9 3 T64-7/02428 23.5 81.1 57 2.3 5.0 1 28.3 1 3

a Standard evaluation system for rice scale.

IRRN 17:4 (August 1992) 7

46/102428 (see table). None, however, exceeded the check Shanyou 10 (Zhenshan 97 A/Milyang 46). The hulling (brown rice) rate of most of the hybrids was higher than that of their parents and of the check combination, averaging 8 1.4%.

Grain length was between that of their corresponding parents, and usually more

similar to that of the longer grained parent. All hybrids showed some chalkiness, but were far less chalky than 02428.

Amylose content (AC) was 16.9- 28.3%. AC of Minghui 63/102428 and IRI371/02428 exceeded that of their high parent whereas that of IRI361/02428 and Milyang 46/02428 was below that of

their low parents. None of the six hybrids displayed an obvious gel consistency pattern. Alkali digestion values averaged around 4.

The results indicate that the grain quality of the six intersubspecies hybrids was superior to that of the leading intrasubspecies combination Shanyou 10.

Phenological and quality aspects of grains of rice O. sativa L.

A. A. Vidal and M. D. Asborno, Estacion Experimental Ing. Agr. Julio Hirschhorn, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de la Plata, Buenos Aires, Argentina

Environmental conditions influence the phenological and quality characteristics of rice grain. Lower ambient temperatures during rice growth shorten the germination and vegetative phase.

Lower temperatures during grain development tend to produce higher amylose content (AC) levels and lower values for gelatinization temperature (GT) of starch than at average temperatures.

Alkali spreading value and amylose content of commercial grain types under 2 ambient temperatures. a

Alkali spreading value b

Grain type Varieties (GT index) Amylose content b (% db) (no.)

Temp A (21.9 °C) Temp B (18.6 °C) Temp A (21.9 °C) Temp B (18.6 °C)

Medium 3 5.63 a 5.71 b 12.5 a 17.4 b Long-wide 3 5.28 a 5.76 b 18.1 a 19.5 b Short 2 6.42 a 6.51 b 16.2 a 17.5 b Long-slender 17 5.20 a 5.62 b 22.7 a 23.1 b

GT LSD (0.05) = 0.13 AC LSD (0.05) = 0.91 CV (%) = 3.06 CV (%) = 6.87

a A =normal temperature condition (21.9 °C), B = 30 d after October (18.6 °C). In the row, values with the same letter are not significantly different at the 5% level.

We studied the effect of ambient (see table). AC ranged from 14% in temperature on 25 rice varieties for 3 yr Norin 20 to 27% in IRGA409. We under two temperature conditions. divided the varieties into four sample

The experiment was laid out in a groups based on their commercial grain random block design with four types: medium, long-wide, short, long- replications in factorial 2 × 4 × 4. Alkali slender. Under the two temperatures, the spreading value ranged from 2.5 in groups differed significantly in AC and Century Patna 231 to 7 in IRGA409 GT (see table).

Pest resistance—diseases research are in Table 1. Pi-z t is a multiple

Reexamination of linkage relationships between blast (BI) resistance genes Pi-i and Pi-z using near-isogenic lines (NILs) of rice

K. Ise, National Agricultural Research Center (NARC), Tsukuba, Ibaraki, Japan

Pi-i and Pi-z are in the sixth linkage group on current linkage maps. Pi-z was reported to have linkage relations to marker genes C, alk, and Lm (Se-1), all belonging to the sixth linkage group. The Pi-i locus was reported to be linked to the

allele of the Pi-z locus, which was We have been developing NILs by introduced to a japonica line from an

repeatedly backcrossing the Japanese indica variety. cultivar Nipponbare to different sources Seedlings of parental lines and F 2 of resistance to the B1 fungus Pyricularia plants were grown in a greenhouse. They oryzae Cavara. The recurrent parent is a were inoculated at the four- to five-leaf japonica cultivar susceptible to most of stage by spraying with an aqueous spore the B1 isolates collected in Japan. The suspension of about 3 × 10 5 conidia/ml. NILs are similar to Nipponbare in height, Isolates IBOS 1-1-1 and Ken 54-20 were maturity, and appearance. The pedigrees used as the inoculum. They belong to the and resistance genes of NILs used in this most common race in Japan, race 3.

Table 1. Pedigrees of NILs with BI resistance.

Source of resistance Line Resistance Pedigree a

gene Cultivar Origin Pi-z locus, with a recombination value of about 30% in the repulsion phase. I found Kanto-IL 7 Pi-i the loci independent of the other, based on F 2 segregation data using NILs, except for the B1 resistance genes.

a Ou 287 = Fukunishiki/Kiyonishiki Fukunishiki: 597/Zenith//597/3/Hatsunishiki. 73-B205 = Morak Sepilai/5 * Fujisaka 5.

Kanto-IL 5 Pi-z Nipponbare *3//Ou 287/2* Nipponbare Zenith USA Nipponbare *3//Todorokiwase/2* Nipponbare Todorokiwase Japan

Kanto-IL 8 Pi-z' Nipponbare *3//73-B205/2* Nipponbare Morak Sepilai Malaysia

8 IRRN 17:4 (August 1992)

Identification of a new Asian rice gall midge (GM) population in Bhandara District, Maharashtra, India, and highly resistant genotypes

P. S. P. Rao, Central Rice Research Institute (CRRI), Cuttack, Orissa; and H. G. Kandal- kar, National Agricultural Research Program (NARP) Substation, Sakoli, Bhandara District, Maharashtra, India

Four biotypes (I to IV) of the Asian rice GM Orseolia oryzae (Wood-Mason) (Diptera: Cecidomyiidae) from different rice areas of India have been identified and characterized. Earlier trials with limited differentials showed that the Sakoli GM was similar to that from north

coastal Andhra Pradesh (NCAP) (biotype IV). Many GM-resistant rice donors and cultures, however, were susceptible at Sakoli, an area where GM is endemic. We studied 36 donors and cultures with known reactions to the biotypes during 1990 and 1991 kharif (monsoons).

The seed originated from CRRI's insect-resistant donor garden. It was selected over several years for GM resistance under high GM pressure in the field.

The entries were transplanted in early August in Cuttack and in late August in Sakoli to allow for peak GM infestation by the 50-60 d after planting. We adopted

Table 2. Segregation for reaction to 2 isolates (race 003) of Pyricularia oryzae in the F 2 populations between NILS. a

Seedlings (no.) Goodness of fit

Resistant Susceptible Total (3:l) (15:l) Probability Cultivar, line, or cross

Isolate IBOS 1-1-1 Nipponbare (±) 0 9 9

NipponbareKanto-IL 7 146 53 199 0.2831 0.50 - 0.60 Kanto-IL 7 ( Pi-i ) 10 0 10

Nipponbare (±) 0 8 8 Kanto-IL 8 ( Pi-z t ) 9 0 9 NipponbareKanto-IL 8 148 42 190 0.8491

Nipponbare (±) 0 10 10 Kanto-IL 5 ( Pi-z ) 10 0 10 NipponbareKanto-IL 5 143 51 194 0.1718

0.30 - 0.40

0.60 - 0.70

Isolate IBOS 1-1-1 Nipponbare (±) 0 39 39 Kanto-IL 7 ( Pi-i ) 10 0 10 Kato-IL 8 ( Pi-z t ) 9 0 9 Kanto-IL 7Kanto-IL 8 350 26 376

Nipponbare (±) 0 41 41 Kanto-IL 5 ( Pi-z ) 10 0 10 Kanto-IL 7 ( Pi-i ) 10 0 10 Kanto-IL 5/Kanto-IL 7 462 35 497

Isolate Ken 54-20 Nipponbare (±) 0 10 10 Kanto-IL 7 ( Pi-i ) 10 0 10 Kanto-IL 8 ( Pi-z t ) 10 0 10 Kanto-IL 7/Kanto-IL 8 184 13 197

Nipponbare (±) 0 10 10 Kanto-IL 5 ( Pi-z ) 10 0 10 Kanto-IL 7 ( Pi-i ) 10 0 10 Kanto-IL 5/Kanto-IL 7 19 1 13 204

0.2837 0.50 - 0.60

0.5324 0.40 - 0.50

0.0409 0.80 - 0.90

0.0052 0.90 - 0.95

a Blast resistance gene for each line is in parentheses.

Disease reactions were scored about 7 d after inoculation.

Inoculated seedlings clearly segregated into resistant and susceptible classes. Each segregation of F 2 populations derived from crosses between three NILs and the recurrent parent gave a good fit to a 3 resistant: 1 susceptible ratio. This shows that each NIL has a single dominant gene for resistance to the isolate IBOS 1-1-1 (Table 2).

derived from crosses between the NIL with Pi-i and the NILs with Pi-z or Pi-z t gave a good fit to a 15 resistant: 1 susceptible ratio. This indicates that two independent dominant genes conferred resistance to the isolates belonging to race 3 (Table 2). These segregation patterns indicate no linkage relationships between Pi-i and Pi-z loci.

Some workers previously used breeding lines with Pi-z derived from distantly related crosses and a Japanese cultivar with Pi-i genetic analyses. These different genetic backgrounds or modifier gene(s) may cause an excess of resistant segregants in the F 2 populations, suggesting linkage in the repulsion phase. The NILs provide excellent material for characterizing each gene and for further genetic and pathologic studies.

Each segregation of four F 2 populations

Pest resistance—insects

Reaction of differentials to Indian GM biotypes from different locations, 1990-91 kharif. a

Biotype Location Eswara- Orumun- CR308- CR309- PTB10 R296- CR157- Vellu- CRS7-Kaka- korra dakan 408 268 120 212 tha- MR tiya

Reaction of differentials

cheera 1523

I Warangal, Andhra R R R R R R R R R R Pradesh (AP)

III Ranchi, Bihar II Cuttack, Orissa S R R R R R R R R S

IV Srikakulam, North S R R R R R R S R S R - - R R R R R S R

Coastal AP V Sakoli, Maharashtra R S S S R R R R R S

a S = susceptible, R = resistant.

IRRN 17:4 (August 1992) 9

c 2 c 2

resistant donors such as PTB20, Kochuvithu, Karivennel, IRl539. PTB33, ARC6650, and IR1561, and

Triveni, and Jaya were used. Promising selections were obtained

from crosses IR8/PTB20, IRl1/ Kochuvithu, IR8/Karivennel, Trivenil IR1539, Jaya/PTB33, ARC6650/Jaya, and IR1561/PTB33. Eight varieties were released from them during 1978- 90.

We studied the reaction of seedlings to the local BPH biotype using the bulk seedling test. Varieties were also screened in the field under heavy natural incidence. Resistance was scored using the Standard evaluation system for rice. Results are presented in the table.

cultural practices to favor high GM buildup, including close spacing (15 × 15 cm), continuous standing water of 2-5 cm, and frequent N application. Susceptible checks Jaya in Cuttack and TN1 in Sakoli were interspersed in the plots at the beginning, end, and after every 10 test entries to serve as indicators for GM buildup. Only plants completely free from infestation were rated resistant (R), while those showing any infestation rated susceptible (S).

TN1 had 100% GM-infested hills and 75-89% infested tillers (silvershoots). Jaya had 99-100% infested hills and 59- 73% infested tillers.

Damage ratings were consistent in both years at both centers. Entries S in Sakoli but R in Cuttack were

Leaung 152, Shakti, Samalei, OB677, Orumundakan, CR294-548, CR3 17-

ARC5158, ARC6221, RPW6-4 (S.S),

166, CR319-644, CR315-621, CR318- 548-7, CR410-3225, CR410-3225-2, CR308-408, CR309-268, ARC5984, Swimphul, CR394-6056, CR410-6018. and CR392-5085-2.

Entries R in both Sakoli and Cuttack were AC1224, MNP76, PTB10, Banglei, CR57-MR 1523, CR311-134, CR157-212, Aganni, Eswarakorra. Velluthacheera, NHTA 8, and T1477.

Brown planthopper (BPH)- resistant varieties developed at Moncompu, Kerala modern varieties such as IR8, IR11,

N. R. Bai, S. S. Nair, R. Devika, A. Regina, S. Leenakumary, D. S. Radhadevi, and C. A. Joseph, Rice Research Station (RRS), Kerala Agricultural University, Moncompu, India

The BPH Nilaparvata lugens (Stål) has caused extensive damage to Asian rice crops. Although the pest was reported in Kerala during 1958 and 1962, the first severe outbreak occurred in 1973-74, damaging about 50,000 ha of rice. Grain yield loss was 10-70% and at times reached 100%.

approach to BPH control.

varieties began in 1973 at RRS. BPH-

Host plant resistance is the logical

Breeding programs for BPH-resistant

Plant characters and BPH score of selections bred for BPH resistance in Kerala, India.

Reaction to Plant Crop Panicles Grain Grain Protein BPH b Release

Variety Parentage height duration (no./ yield type a content (year) (cm) (d) hill) (t/ha) (%) Lab Field

MO 4 (Bhadra) IR8m/PTB20 81 120 c 20.0 5.5 SB 10.2 2.8 2.5 1978

MO 5 (Asha) IR11/Kochuvithu 85 120 7.5 6.0 LB 9.4 2.6 2.5 1980 MO 6 (Pavizham) IR8/Karivennel 90 120 7.5 6.0 SB 7.5 2.0 2.3 1982 MO 7 (Karthika) Triveni/IR1539 90 110 7.5 6.5 LB 10.6 2.0 2.0 1985 MO 8 (Aruna) Jaya/PTB33 90 110 12.0 6.5 MB 9.6 2.2 1.7 1990 MO 9 (Makam) ARC6650/Jaya 85 110 12.0 6.5 SB 9.4 1.7 2.5 1990 MO 10 (Remya) Jaya/PTB33 110 120 10.0 6.5 LB 10.9 2.3 2.6 1990 MO 11 (Kanakam) IR1561/PTB33 110 125 8.0 7.0 MB 9.5 1.6 2.0 1990 TN1 (susceptible 75 105 12.0 – MB – 9.0 9.0 –

PTB33 (resistant 135 130 6.0 – MB – 2.7 2.3 –

135 d

check)

check)

a Cooking quality of all selections was good. SB = short bold, LB = long bold, MB = medium bold. All test varieties have red kernels. b By the Standard evaluation system for rice. c Dry season. d Wet season.

10 IRRN 17:4 (August 1992)

Orumundakan and its derivatives CR308-408 and CR309-268 were R in NCAP but S in Sakoli, Eswarakorra was R in Sakoli but S in NCAP, and Velluthacheera was S in NCAP but R at Sakoli. Sakoli GM was also different from that in Ranchi (III). CR57-MR 1523 was R in Sakoli and S in Ranchi; Kakatiya was the opposite. Eswarakorra was R at both locations. PTB10 and its derivatives R296-120 and CR157-212 were R at all locations. Sakoli GM populations should be treated as a distinct biotype based on these results.

Pest resistance— other pests Upland rice cultivars resistant to parasitic weed Striga hermonthica

Z. Harahap, J.C. Olela, K. Ampong-Nyarko, and R. C. Saxena, Mbita Point Field Station (MPFS), ICIPE, P.O. Box 30, Mbita, Kenya

Striga spp. are parasitic weeds of maize, sorghum, millet, and upland rice in Africa. No single method exists for controlling striga effectively. The pink- colored S. hermonthica (Del.) Benth. has become a serious problem in upland rice in western Kenya. We studied whether rice cultivars differed in relative resistance to S. hermonthica.

sources were evaluated for reaction to striga during the 1990 short-rains cropping season (Sep-Dec). We conducted the experiment in a farmer’s field that had a history of striga incidenct at Mbita Point under rainfed upland conditions (900 mm rain/yr). The soil is a calcaro-vertic Fluvisol with pH 8.1 and 0.9% organic C; each 100-g sample has CEC 37.5 meq, 0.1 meq K, and 36 meq P. Rice was planted in rows, 30 cm apart in 3- × 5-m plots, with four replications.

Striga plants were uprooted from plots at 95 d after rice emergence, dried, and weighed. Rice entries IR38547-B-B-B-7-

and IR49255-B-B-5-2 were striga-free

Forty upland rice lines from various

2-2, IR47255-B-B-5-4, IR47697-4-3-1,

We collected 1,600 samples of traditional rice germplasm in 1990-91 from 13 of

Cambodia’s 21 provinces with the help of officials in the Ministry of Agriculture’s Agronomy Department. Most of the cultivars were from rainfed lowland fields. Apparent duplicates were removed, leaving 373 new cultivars. These were direct seeded on 13 Aug 1991 at Prey Phdau Research Station, Kampong Speu. Twenty-two of the 373 did not germinate. Floodwater inundated the field 8 d after sowing. Seedlings

Screening of rice germplasm against natural flooding in Cambodia

Drought tolerance of best yielding entries, Tamil Nadu, India, 1990. a

Initial Grain Plant Evaluation Cross or variety yield height Trial no. (t/ha) (cm)

11371 10743

– –

11522 9866

Pankaj/T141 Orumundakam/CRRI Pankaj Salivahana Mahsuri/IR2071-176-1-1 Pankai/Swarnadhan

LSD (P = 0.05)

2.3 101 2.2 114 2.1 99 1.8 105 1.2 90 1.2 105 0.4 7

a No yield was measured for IET10658 (Phalguna/PTB21/ PTB33), IET10717 (Phalguna/Andrewsali), IET10722 (Nagarjuna/ARC5984), IET10738 (IR36/OR127-1), IET10754 (Phalguna/Andrewsali), IET10761 (Nagarjuna/ ARC5084), IET10785 (Phalguna/Andrewsali), IET10797 (CR149-288/T142),IETl1524(IR20/IR25),IETI1525(IR20/ IR15), IET11537 (CR151/CR1014), IET11537 (Nagarjuna/ Magila), IET311374 (CR130-36/Jaganath), IET11395 (IET6858/ARC6172), IET11396 (IET6858/ARC6172), and Nagarjuna.

We evaluated 22 shallow water rice entries for drought tolerance under field conditions. The experiment was laid out

in a randomized block design with three replications. Seeds were sown 25 Jun 1990 and transplanted on 19 Jul 1990 in the main field in 7- × 2-m plots and at spacing of 15 × 10 cm.

The crop was irrigated every 10 d until 55 days after sowing (DAS) after which irrigation was stopped. Rains occurred at 120-125 DAS (110 mm) and 150-165 DAS (200 mm). We scored drought tolerance and drought recovery at 105 DAS and 125 DAS using the Standard evaluation system for rice. All rice entries were grown to maturity.

Drought during late vegetative phase (55-110 DAS) and milk stage (125-140 DAS) severely affected the entries. Only six of the 22 entries yielded grain (see table). All six had tip drying to 1/4 of the length of most leaves. The nonyielding entries were chaffy and had unfilled grains because of the drought at the milk stage.

IET11371, IET10743, and Pankaj recorded yields of > 2.1 t grain/ha, and 70-89% of the plants recovered. In contrast, Salivahana, IET11522, and IET9866 yielded 1.2-1.8t grain/ha, apparently because only 40-60% of plants recovered.

Dry weight of striga plants uprooted from field plots planted to selected rice entries at 2 sites in South Nyanza District, western Kenya. a

Mbita Point, 1990 short rains Ungoye, 1991 long rains

Entry Dry wt Rating b Dry wt Rating b

(g/15m 2 ± SD) (g/15 m 2 ± SD)

IR38547-B-B-B-7-2-2 0.0 ± 0.0 HR 0.0 ± 0.0 HR IR47255-B-B-5-4 0.0 ± 0.0 HR 6.0 ± 7.1 R IR47697-4-3-1 0.0 ± 0.0 HR 0.0 ± 0.0 HR IR49255-B-B-5-2 0.0 ± 0.0 HR 2.5 ± 3.8 R B3913F-16-5-ST-42 4.5 ± 0.6 R Ble Chai 7.5 ± 0.6 R 6.5 ± 7.9 R

6.0 ± 1.6 R

Nam Roo 1520.0 ± 45.8 HS 105.3 ± 156.8 S ITA257 1251.0 ± 95.0 HS 73.0 ± 78.8 S

UPR103-80-1-2

IR47686-B-B-2-2 1460.0 ± 90.0 HS 553.3 ± 811.4 HS

489.0 ± 757.6 HS IR47686-13-2-1 (susceptible check)

CV 10.8 304.9 a Data selected from 40 entries. b R = highly resistant, R = resistant, S = susceptible, HS = highly susceptible. c Not tested.

and rated as highly resistant (see table). like, leaf-wilting symptoms and were Entries B3913F-16-5-ST-42 and Ble rated as susceptible to highly Chai had light infestation and were susceptible. rated as resistant. The remaining striga- Ten entries were reevaluated during infested, stunted entries had drought- 1991 long-rains season (Mar-Jul) at

Ungoye (Eutric Cambisols, pH 6.1, CEC 48.2 meq/100 g soil, 0.2% N, 1.6% organic C, 98 meq P/100 g soil, 1,000 mm rainfall), about 40 km southwest of MPFS.

We planted entries in 3- x 5-m plots, replicated four times, in a randomized block design. Striga plants were removed 90 d after rice emergence from plots, dried, and weighed. Two of the four cultivars rated as highly resistant at Mbita Point were also highly resistant at Ungoye. Nam Roo and ITA257, rated as susceptible at Mbita Point, were moderately resistant to S. hermonthica at Ungoye, indicating a possible genetic variability of the populations. Check IR47686-B-B-2-2 was susceptible at both sites.

Our tests showed that some of these rice cultivars can possibly be used to breed for striga resistance in upland rice.

Stress tolerance—drought

Performance of shallow water rice for drought tolerance

G. Nallathambi and J. G. Robinson, Agricul- tural Research Station, Thirupathisaram 629901, Tamil Nadu, India

Stress tolerance—excess water

V. N. Sahai and R. C. Chaudhary, Cambodia- IRRI Rice Project, International Rice Research Institute, P. O. Box 01, Phnom Penh; and S. Sovith, Agronomy Department, Phnom Penh, Cambodia

IRRN 17:4 (August 1992) 11

- c

remained submerged for 6 d in water up to a maximum depth of 150 cm.

We scored submergence tolerance on a 1-9 scale 5 d after the flood receded. Some degree of submergence tolerance (score 1-5) was recorded in 75% of the cultivars (Table 1). This percentage of submergence tolerance is more than 10 times more than the percentage of varieties showing submergence tolerance from 18,256 entries screened at IRRI. This greater submergence tolerance may be due to the greater frequency of flooding in Cambodia and the natural selection for submergence tolerance occurring in farmers’ fields.

The severity of submergence used here was similar to that in tests of the International Rice Germplasm Center (IRGC) as scored in two common cultivars; Srau Timor (score 5 on both tests) and Srau Thougon (score 7 on our test and score 9 in IRGC tests). A submergence score of 1 was recorded for entries from 5 of 13 provinces (Table 2).

Submergence score of 3, however, was recorded for these entries from nine provinces: Bak Changkes, Damnoeub Krape, Khmao Kdet, Khnang Khmaing, Kho, Kmean Chmous, Kong Keo, Krachak Chhrouk, Krachak Ses, Neang Table 1. Submergence tolerance score of 351 rice germplasm. Cambodia, 1991.

Submergence Entries Entries (n = 18,256) tolerance (n = 351) scored at

score IRRI (%) no. %

1 8 2.3 2 3 34 9.7 1 5 220 62.7 2 7 67 19.0 5 9 22 6.3 91

Table 2. Outstanding submergence-tolerant rice germplasm (submergence score 1) from Cambodia, 1991.

Access- Province from ion no. Cultivar which collected

I364 Angkear Kampong Thom 1441 Damnoeub Sabai Bat Steung Treng I442 Damnoeub Ses Svay Rieng 1446 Damnoeub Tong Sanke Pur Sat 1464 Khgneng Kampong

1467 Khmang Romeang Kampong

1488 Kong Sar Kampong Thom 1489 Kong Say Pur Sat

Chhnang

Chhnang

12 IRRN 17:4 (August 1992)

Noy, Damnoeub Thnot, Kantourt Sa, Ang Kourt, Kaun Chen, Khmao, and Khpor Daung, Neang Noury, Neang Noy, Kaun Trai. Neang Rose, Neang Rovis, Neang San Cultivars scoring 1 and 3 would be Kok, Sneng, Bantey Meas, Kantuy useful for areas where fields are flood- Damrei, Khneng Chnot, Clay, Dang Dav, prone at the early vegetative stage. They Kong Soy, Neang Yi, Kong Bak Roteh, can also be used as donors for breeding Sevith, Ansar Chang Kom, Khpor Daung, submergence-tolerant rices.

Stress tolerance—adverse temperature

Evaluation of indica/ japonica crosses during boro season in West Bengal

S. K. B. Roy and S. Biswas, EIRRP, Rice Research Station, Chinsurah 712102, West Bengal, India

Indica/japonica crosses have reportedly performed well in areas where low temperature inhibits rice crop growth and yield. Boro (dry season) rice grown after lowland or deepwater rice in West Bengal experiences low temperature (10-15 °C) during early growth stages. Low temperature lengthens the crop duration, putting the reproductive phase into summer (Apr-May). High air temperature (35-40 °C) and premonsoon rain during this period occasionally damage boro rice.

Farmers grow short- to medium- duration, semidwarf modern varieties (MV) that average 4-5 t grain/ha. The congenial climate, however, makes it feasible to increase yields above the present level.

Nineteen indica/japonica advanced lines were obtained from IRRI and evaluated for seedling vigor, earliness, and high grain yield. Traditional, tall, boro variety CB1 and the promising, short-duration MV UPR103-80 were also evaluated in on-farm trials at Sonarhati village, Chinsurah, during 1990-91 boro. Minimum temperature between sowing and 45 d after sowing (DAS) was 10.8- 11.1 °C. Cold tolerance, based on the amount of leaf yellowing, was recorded at 15, 30, and 45 DAS in the seedbed.

and IR52418-B-B-B-6-2-1 were promising for cold tolerance and increased grain yield. IR8866-30-3-1-4-2 had the best average cold tolerance score (see table).

CB1 was tallest at 45 DAS followed by IR8866-30-3-1-4-2, which had the highest leaf number at 45 DAS. Indica/ japonica lines yielded 13-15% more grain than UPR103-80. Grain type of indica/ japonica crosses was comparable with that of CB1 and UPR103-80. Indica/ japonica derivatives can possibly be used for varietal development programs in boro rice.

IR8866-30-3-1-4-2, IR39739-7-4-3-1,

Cold tolerance and grain yield in promising indica/japonica crosses. Chinsurah, West Bengal, 1990-91 born season.

Av cold Seedling Leaves Days Grain Entry Type tolerance ht (cm) at (no.) at to 50% yield

(0-9 scale) 45 DAS 45 DAS flowering (t/ha)

IR8866-30-3- 1-4-2 Indica/japonica IR39739-7-4-3-1 Indica/japonica IR52418-B-B-B-6- Indica/japonica

CB1 Tall indica UPR103-80 Semidwarf indica

2-1

Mean F value a

LSD (0.05)

3.6 10.6 4.0 9.0 4.1 9.0

3.8 15.0 5.3 9.0

4.2 10.5 10.4** 41.3** 0.6 0.5

4.2 114 3.2 116 3.0 112

3 .0 114 3.6 116

3.4 114 8.55** 10.5** 1.4 0.6

7.4 8 .0 6.8

4.1 6.0

6.6 40.5**

0.6 a ** = significant at the l% level.

high-yielding, recommended variety for the zone (Table 1). Mukthi also resisted diseases better than Shakti (Table 2).

Mukthi is potentially suitable for the rabi crop of the coastal region of Karnataka.

Integrated germplasm improvement—irrigated KAU170, a promising short- duration rice variety resistant to brown planthopper (BPH)

N. Remahai, A. Regina, R. Devika, S. Leenakumari, D. S. Radhadevi, and C. A. Joseph, Rice Research Station (RRS), Kerala Agricultural University, Moncompu, Kerala, India

BPH was a serious problem in Kuttanad from 1973 to 1974. A hybridization program was started at RRS in 1976 to develop a BPH-resistant, short-duration variety using locally accepted modem varieties and BPH-resistant, tall varieties, such as Ptb 33 and ARC6650.

KAU170 from the cross ARC6650/ Jaya performed well in trials for yield and pest resistance. KAU170 (IET9268) was released in 1990 as Makam (MO 9) for use during the three seasons in Kerala. It is a short- duration (110 d), dwarf (75-80 cm) variety with red kernels, short bold grains, resistance to BPH, and seed dormancy of 2 wk.

KAU170 performed well against locally accepted modem varieties in many field trials at numerous locations (see table). When screened for pests and diseases, it showed moderate resistance to sheath blight, sheath rot, stem borer, gall midge, and leafhopper.

Performance of Makam in yield trials.

Grain yield (t/ha)

Makam Check variety a

Trial and location

RRS field trial, Moncompu, 1983-84 5.6 4.9 Multilocation trial, 1983 3.7 3.4

Multilocation trial, 1984 6.1 5.4

All India Coordinated trials 4.2 3.3

(12 locations)

(10 locations)

Brown Planthopper Resistant Variety Trial (BPHRVT), 1988 (11 locations)

(10 locations) Farm trials. 1987-88 3.6 2.7

a Jyothi at RRS. Moncompu, multilocation and farm trials, and MR1523 for BPHRVT.

Performance of Mukthi (CTH1) in coastal Karnataka, India

N. S. Parameshwar, T. K. Prabhakara Setty, T. A. Sreerama Setty, C. C. Malleshappa, N. A. Janardhana Gowda, and M. Mahade- vappa, University of Agricultural Sciences, GKVK, Bangalore 560065, India

The coastal zone of Karnataka is a narrow strip of land lying between the Arabian Sea on the west and the Western Ghats on the east. Rice is cultivated on about 0.2 million ha during three cropping seasons. Rainfall averages around 4,000 mm, the majority of which falls during kharif (Jun-Sep) when mostly rainfed rice is grown. Rice is an irrigated crop during winter (Oct-Jan).

Mukthi is a red-kerneled, high- yielding variety with cold tolerance and blast resistance recommended for southern Karnataka. It is well-suited to winter. Its performance in the coastal zone has been studied during rabi (dry season) under irrigated conditions in lowland farming situations.

Research Station, Brahmavar, and the Agricultural Research Station, Kankanady, during 1989-90 and 1990- 91, Mukthi consistently yielded 16% more than the local check Shakti, a

In field trials at the Regional

Table 1. Yield of Mukthi (CTH1) in coastal Karnataka, India.

Location Grain yield (t/ha)

Mukthi Check (Shakti) Trial

Regional Research Station, Brahmavar, 1989-90, 1990-91

– Agricultural Research Station, Kankanady RRS, Brahmavar, 1990-91

Red rice varietal trial 4.1 3.2

Blast tolerance varietal trial 3.8 3.6 Mid-duration varietal trial 5.2 4.9 Uniform varietal trial 4.1 3.6 Demonstration plot 3.8 3.2

Mean 4.2 3.7

Table 2. Reaction a of Mukthi (CTH1) to diseases in coastal Karnataka. b

Variety Leaf spot b Leaf blast b Neck blast (%)

Mukthi 3.4 2.3 1.7 Shakti 3.9 2.7 3.2

a Mean of 4 trials. b Scored with the Stantdard evaluation system for rice (SES) on a scale of 0.9.

Remya—a new brown planthopper (BPH)-resistant, medium-duration variety from Kerala

N. Remabai, A. Regina, R. Devika, S. Leenakumary, D. S. Radha Devi, and C. A. Joseph, Rice Research Station (RRS), Moncompu, Kerala, India

BPH is a threat to rice production in Kerala, especially in Kuttanad, which is a unique delta area with 52,000 ha of riceland, 0.5-2.0 m below sea level. Wet

season (Dec-Jan to Mar-Apr) rice harvest coincides with the monsoon. Rice grains often germinate on the panicle before harvest. BPH has become endemic because of the warm, humid conditions. Kuttanad farmers use modem varieties, none of which have seed dormancy and BPH resistance.

Remya (MO 10)—culture KAU126 (IET9266), derived from the cross Jaya/ Ptb 33—was released by RRS in 1990. Remya is a medium-duration (120 d), BPH-resistant variety with seed dormancy of up to 1 mo. It has red

IRRN 17:4 (August 1992) 13

Table 1. Remya (Mo 10) yields in Kerala, India.

Grain yield (t/ha)

Remya Check variety b

RRS, Moncompu (field trials) 5.1 4.5 Multilocation trials 1983-84 6.8 5.4

wet season (5 locations)

BPHRVT, 1984 dry season (11 locations)

(8 locations)

1988-89, 2 seasons (7 locations)

All India Coordinated trials 4.9 3.3

BPHRVT, 1985 dry season 4.6 3.2

Farm trials 5.0 4.2

a BPHRVT = Brown Planthopper Resistant Variety Trial. b Jaya for research station and multilocation trials, MR1523 for BPHRVT 1984, IET7575 for BPHRVT 1985, and Pavizham for farm trial.

RCPL 1-1C, a cold-tolerant rice for high-altitude areas of Meghalaya, India

D. K. Pandey, H. S. Gupta, S. Kumar, G. C. Munda, and M. Ram, Indian Council of Agricultural Research (ICAR), Research Complex for North-eastern Hill (NEH) Region, Umroi Road, Barapani 793103, Meghalaya, India

Suboptimal temperature at reproductive phase, neck blast, and sheath rot are the major constraints to increasing rice production in high-altitude areas of NEH in India. Many exotic and indigenous lines from the National Cold Tolerance Nursery and the International Table 1. Yield of RCPL 1-1C in Upper Shillong, India, 1985-90.

Grain yield (t/ha)

1985 1986 a 1987 1988 1989 1990

RCPL 1-1C 2.3 1.6 3.6 4.2 2.8 3.1 Khonorullo 1.9 1.3 2.9 3.3 2.1 2.5 Increase 22 25 24 28 25 16

Cultivar

over check (%)

a Severe rat damage (>50%).

Table 2. Yield of RCPL 1-1C in 2 farmers’ fields in Meghalaya.

Grain yield (t/ha)

Mylliem Sohiong (1700 m) (1650 m)

Variety

RCPL 1-1C 2.9 2.3 Khonorullo 1.7 2.0

14 IRRN 17:4 (August 1992)

Table 2. Remya reaction a to pests and diseases at RRS, Moncompu, India.

Brown spot Variety Sheath Sheath Blast Gall BPH

blight rot Leaf Grain midge

Remya 1.4 3.0 1 .0 1 .0 1.2 3 .0 2.3 TN1 2.8 3.2 5.0 1.2 4.4 5 .0 9.0

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

kernels and long bold grains which are of 50 entries. In farm trials during 1988- qualities preferred by Keralites. It is 89, it outyielded the check variety in semitall (100-110 cm). seven locations. Reactions to different

1983-84, it outyielded the check variety 2. Jaya (Table 1). In All India Coordinated Remya is recommended for all three yield trials it ranked second out of 54 seasons in Kerala. entries in 1984; in 1985, it ranked 7th out

In field and multilocation trials in pests and diseases are presented in Table

Rice Cold Tolerance Nursery were evaluated at various growth stages. Most of them either exhibited poor spikelet fertility or did not set seed at all. Even the well-known cold-tolerant cultivars Stejaree 45, Barkat, Eiko, K39, K332, and CH1039 exhibited high spikelet sterility (>80%). Local cultivars, however, possess cold tolerance and have low spikelet sterility (<30%).

ICAR has developed a new line, RCPL 1-1C, at the experimental farm of Upper Shillong (1,850 mean sea level [msl], 25°32’N, 91°51’E), where average minimum and maximum temperatures are 11 and 19 °C at seedling stage, 15 and 20 °C at tillering and panicle initiation, and 9 and 18 °C at ripening. These temperatures are suboptimum for rice growth. Soil of the experimental area is loam with pH 5-4, 5.5% organic C, 11.8% clay, 46.3 ppm available P, and CEC 24.5 meq.

RCPL 1-1C, derived from Pusa 331 Khonorullo, is a cold-tolerant, high-

yielding indica rice. It matures in 165 d at high altitude (>1,300 msl), has moderate tillering (5-6) and semidwarf stature (90-95 cm), and is tolerant of low temperature (15-20°C) and short daylength (2-2.5 h sunlight/d) at the reproductive phase. It is also moderately tolerant of cold at the vegetative phase.

It has 1,000-grain weight of 22-23 g, and moderate resistance to blast and sheath rot. Yields range from 3 to 3.5 t/ ha. Its spikelet sterility is very low (<20%) at optimum transplanting time (1st week of June) but becomes higher (40-50%) with later transplanting (up to last week of June).

In on-farm trials during 1985-90, mean yield was 2.3-4.2 t grain/ha, showing an advantage of 16-28% over Khonorullo, a local cold-tolerant cultivar (Table 1). It also did well in farmers’ fields in adaptive trials in Meghalaya (Table 2).

Kernels are medium slender and red.

Space limitations prevent IRRN from publishing solely yield and yield component data from fertilizer field trials that are not conducted for at least two cropping seasons or at two differing sites. Publication of work in a single season or at one site is limited to manuscripts that provide either a) data and analysis beyond yield and yield components (e.g., floodwater parameters, microbial populations, soil mineral N dynamics, organic acid concentrations, or mineralization rates for organic N sources), or b) novel ways of interpreting yield and yield component data across seasons and sites.

CROP AND RESOURCE MANAGEMENT Fertilizer management—inorganic

~

Phosphorus effects on rice yield under different moisture regimes during wet season in West Bengal, India

A. Zaman, S. Mallick, P. Bandhopadhaya, and N. Mukhopadhaya, Bidhan Chandra Krishi Viswavidyalaya, Kalyani 741235, West Bengal, India

We conducted a field trial from 1986 to 1988 to study how P affected rice yield during wet season under different moisture regimes at a seed farm in Memari, Burdwan, in the Gangetic alluvial plains of West Bengal.

Soil is silt loam with pH 6.8, 0.9% organic C, CEC 15 meq/100 g soil, 73 kg available P/ha, and 21 6 kg exchangeable K/ha in the top 15 cm of soil.

The experiment was laid out in a random block design, replicated three times. P was applied as single

superphosphate (16% water soluble and 2% citric soluble P 2 O 5 ) at 0, 30, 60, and 90 kg P/ha under three moisture regimes (see table). The crop received the recommended 80 kg N/ha and 41 kg K/ha and 48, 67, and 60 cm of rain during the growth periods in respective years. Irrigation was supplied as per treatment. IR36 raised in wetbed (60 kg seed/ha) was transplanted 30 d after seeding at 25- × 25-cm spacing with 2 plants/hill.

P up to 26 kg/ha significantly increased grain yield regardless of irrigation regime (see table). Grain yield was greater with continuous flooding at all P levels; however, grain yield/unit water input increased by 60% in the I 2 treatment compared with the continuous flooding. These results suggest that P fertilizer and irrigation water are substitutive inputs with regard to their interactive effects on yield. For example, total water input decreased by more than 40% from treatment I 0 to I 2 based on comparison of the pooled means. In

P level effects on IR36 yield under 3 moisture regimes during rainy season in Indo-Gangetic Plains, West Bengal, India.

Year Water use

Moisture Grain yield (t/ha) Total efficiency regime a water use b (kg/ha per cm)

0 kg 26 kg P/ha P/ha

0 kg 13 kg 26 kg 37 kg Mean P/ha P/ha P/ha P/ha

(cm)

1986 I 0 4.1 4.6 5.0 5.1 4.7 88 46.6 56.8 I 1 4.0 4.5 4.8 4.8 4.5 55 72.7 87.3 I 2 3.9 4.4 4.7 4.9 4.5 45 86.7 104.4

I 1 I 2 4.0 4.4 4.7 4.7 4.4 52

Mean 4.0 4.5 4.8 5.0 1987 I 0 4.7 5.2 5.5 5.7 5.3 99 47.5 55.6

4.3 4.6 5.0 5.1 4.7 67 64.2 74.6 76.9 90.4

Mean 4.3 4.7 5.1 5.2

contrast, the I 0 treatment without P inputs and the I 2 treatment with 13 kg P/ha had equivalent grain yields of 4.5 t/ha.

Applying P can help stabilize yields on P-deficient soil when irrigation water is limited.

Fertilizer management— organic

Intercropping green manure (GM) crops with dry season irrigated rice

J. C. Biswas, B. C. Roy, and S. B. Siddique, Agronomy Division, Bangladesh Rice Research Institute, Joydebpur, Gazipur 1701, Bangladesh

Legume crops can restore soil fertility that is depleted because of continuous cropping. But GM crops are rarely used in rainfed wetland rice-based cropping systems. Sesbania aculeata is sometimes intercropped with dry seeded or wet seeded rainfed lowland rice and S. rostrata can grow under flooded conditions. In trials during the 1991 dry season, we evaluated the effect of GM crops on dry season irrigated rice at varied planting dates and the subsequent use of this biomass for succeeding rice production.

Forty-day-old seedlings of BR14 were transplanted 29 Jan 1991 at 20- × 20-cm spacing. S. aculeata and S. rostrata were

Table 1. Yield of rice and GM sown on 4 dates (10, 1988 I 0 4.8 5.3 5.7 5.7 5.3 90 53.3 63.3 20, 40, 60 DT) as affected by intercropping, 1991

I 1 4.5 4.9 5.2 5.3 5.0 65 69.2 80.0 dry season. I 2 4.3 4.7 5.2 5.2 4.9 58 74.1 89.7 Mean 4.5 5.0

4.2 4.7 I 1 5.0 5.1 4.7 62 67.7 80.6 crop I 2 4.0 4.5 4.9 4.9 4.6 52 76.9 94.2 Mean 4.3 4.7 5.1 5.2

5.3 5.4 Pooled I 0 4.5 5.0 5.4 5.5 5.1 92 48.9 58.7 GM

Grain yield GM biomass a

(t/ha) (t/ha)

10 20 40 60 10 20 40

LSD (0.05) 1986 1987 1988 Pooled S. aculeata 2.6 3.4 4.7 4.6 3.9 3.3 0.7 P level 0.2 0.2 0.2 0.1 S. rostrata 3.3 3.3 4.7 4.3 6.9 5.7 0.7 Moisture regime 0.2 0.1 0.1 0.1 Control 4.5 4.4 4.9 4.6 - - -

SE 0.1 0.1 a I 0 = continuous submergence of 5 ± 2 cm irrigation water, I 1 = 5 ± 2 cm irrigation water 5 d after impounded water disappeared, and I 2 = 5 ± 2 cm irrigation water 10 d after impounded water disappeared. Total water use = irrigation water applied (cm) plus a At 60 DT seed germination failed. GM crops were harvested rainfall (cm). on 25 May 1991.

IRRN 17:4 (August 1992) 15

Effect of continuous application of organic manure on the physical properties of soil in a rice - wheat cropping system K. Kumar, O. P. Meelu, Y. Singh, and B. Singh, Soils Department, Punjab Agricultural University, Ludhiana 141004, Punjab, India

Wet season rice followed by dry season (DS) wheat occupies most of the area under irrigation in Punjab. Soils of the region are generally lighter in texture and have high permeability. They are puddled before transplanting rice to maintain submerged conditions. Earlier studies indicated that puddling caused soil structure to deteriorate and to form a

dense layer below the puddled layer. This considerably reduced the yields of the following wheat crop.

We evaluated the physical properties of soil after the 1991 rice crop as influenced by continuous application of organic manure in a rice - wheat cropping system. We started this long-term experiment in 1984-85 DS.

Cumulative infiltration (after rice) as affected by continuous application of different organic manures.

Table 2. Effect of incorporation of organic materials on some plant parameters, 1991 aus. a

N rate Estimated Panicles 1,000-grain Grain Total Savings d from Net Treatment b (kg/ha) N (kg/ha) (no./m 2 ) weight yield loss c for reduced loss

from GM (g) (t/ha) boro and aus N use ($/ha) ($/ha) ($/ha)

P 1 A 30 64 423 b 20.07 a 5.1 a 321.8 9.1 312.7 P 1 R 30 119 461 a 19.42 bc 4.7 ab 289.5 9.1 280.4 P 2 A 30 56 382 c 19.39 c 5.0 a 204.3 9.1 195.2 P 2 R 30 102 432 b 19.38 c 4.8 a 240.0 9.1 230.9 P 3 A 30 13 383 c 19.67 abc 4.3 b 173.7 9.1 164.6 P 3 R 30 15 386 c 19.99 ab 4.7 ab 112.4 9.1 103.3 Control 60 - 389 c 19.45 bc 5.2 a

CV (%) 3.60 1.71 5.9

a Small letters compare means at P 0.05 level by LSD. b P 1 , P 2 , and P 3 are the biomass of GM crops obtained from 10, 20, and 40 DT sowing. A = S. aculeata, R = S. rostrata. c Rough rice @ $0.17/kg. d Urea @ $0.14/kg.

sown after every two rows of rice at 10, Twenty-nine-day-old seedlings of BRl 20, 40, and 60 d after transplanting were transplanted 4 Jun 1991 at 20- × (DT). A split-plot design was used with 20-cm spacing. The treatments were laid three replications. Sowing time was in out in a randomized complete block the main plots and GM crop in the design with three replications. subplots. Plots were 3 × 2 m. Irrigation Recommended fertilizer practices were water was drained out before sowing. followed in both seasons, except that N GM crop seedlings at the 2- to 3-leaf was cut by 50% when GM was used in stage were thinned to 50 plants/m 2 . aus.

crops was incorporated into the soil for grain yield (adjusted to 14% moisture the succeeding 1991 transplanted aus content), and GM biomass (after oven- rice (wet season first crop) cultivation. dried at 70°C for 48 h) were recorded.

Total biomass obtained from the GM Panicles/m 2 , 1,000-grain weight, rice

Rice grain yield was reduced by 22.3- 41.3% at the first and second sowing of GM crops, perhaps because of shading from GM (Table 1). There was no significant yield reduction in the third sowing, but GM biomass production was less.

Panicles/m 2 and 1,000-grain weight differed significantly because of the added organic materials and reduced N in aus season (Table 2). Although GM seemed to contribute more N, aus rice plants do not use it for increased grain yield but rather for late tiller production. The initial slower decomposition of GM may have hampered growth of BR1, a short-duration variety. Heavier grains were obtained from plots with GM + 50% N. The net loss of $103.00-313.00/ha due to intercropping in boro and reduced N use in aus rice indicates that the technology is unsuitable (Table 2).

We conclude that although N can be cut by 50% when 4-6 t GM/ha is incorporated, it is not a profitable system for improving soil fertility.

Physical properties of soil after rice (1991) as influenced by continuous application of organic manures in a rice - wheat rotation. Punjab, India. a

Properties Fallow FYM Summer mung Sesbania LSD (0.05)

Infiltration rate 0.35 0.40 0.55 1.00 0.16 (cm/h), 4 h after onset

Bulk density (g/cm 3 ) 0-5 cm layer 1.48 1.45 1.37 1.36 0.08 5-10 cm layer 1.60 1.60 1.55 1.54 0.03

10-15 cm layer 1.65 1.62 1.59 1.57 0.06 15-20 cm layer 1.66 1.66 1.60 1.55 0.07 20-25 cm layer 1.62 1.64 1.59 1.59 ns 25-30 cm layer 1.56 1.54 1.56 1.52 ns

Water-stable aggregates (%) > 2 mm 13.39 21.75 13.73 15.45 4.94

1 - 2 mm 6.43 5.24 6.59 4.79 1.98 0.5 - 1 mm 7.96 6.96 5.61 7.75 2.89 0.25 - 0.5 mm 7.52 7.50 8.99 10.70 1.69 0.1 - 0.25 mm 6.27 7.05 7.79 11.13 2.40

Rice 5.3 5.2 5.9 5.7 Wheat 4.8 5.0 4.9 4.9

Av grain yield a (t/ha)

a Av of 6 yr.

16 IRRN 17:4 (August 1992)

Soil is a sandy loam (Typic Ustochrepts), with pH 7.3, low organic matter, 0.29% organic C in the top 0-15 cm layer, and no hardpan for 2 m.

Treatments included green manuring (GM) with Sesbania aculeata, summer mung Vigna radiata, and mixing farmyard manure (FYM) in soil before transplanting rice. Average dry biomass added to soil per yr was 5.2 t sesbania/ha, 3.4 t summer mung/ha, and 4.0 t FYM/ha.

We added 90-13-25 kg NPK/ha to the sesbania, summer mung, and FYM treatments during the rice crop and 120- 13-25 kg NPK/ha to the fallow treatment.

Crop management Farmer-participatory rainfed lowland rice varietal testing in Cambodia

R. C. Chaudhary, Cambodia-IRRI Project; and S. Fujisaku, IRRI

Farmer-participatory varietal testing ideally helps to identify superior varieties grown under farmers’ conditions and management, draws farmer feedback regarding varietal characteristics, provides a mechanism for seed multiplication of farmer- desired varieties, and serves as demonstration for nonparticipating farmers.

the Cambodia-IRRI Project showed rice varieties IR66, IR72, and Kru as promising for the rainfed lowlands of Cambodia. Government and nongovernment organizations then distributed seed from on-farm adaptive trials to farmers throughout the country. Methods and goals of the planned farmer-participatory trials were explained to potential cooperators. Interested farmers tested the rice varieties alongside their own cultivars, using their own inputs and management practices. No guarantees were given to cooperators for any crop losses,

Trials in the 1990 wet season (WS) and the 1991 dry season (DS) were on 100-m 2 plots (5 × 20 m) located where hers in the community could easily observe results. Participating farmers

Replicated yield trials conducted by

In the following wheat crop, 120-26-50 kg NPK/ha was added in all the treatments.

We took undisturbed soil cores every 5 cm, up to a depth of 30 cm, for the bulk density measurements, used double ring infiltrometers to measure infiltration, and used wet sieving to estimate the water- stable aggregates.

bulk density (see table). Green manuring with summer mung, up to 10 cm, and sesbania, up to 20 cm, showed significant decreases in bulk density compared with the fallow; maximum decrease was with

Application of FYM did not affect soil

(75 for WS and 39 for DS) provided data on seeding and transplanting dates, fertilizer use, crop problems, yields, and farmer evaluations of the introduced rice varieties. Field days were conducted prior to harvest.

local checks (most commonly IR36 and IR64, or a few local cultivars) did not significantly differ in yield in both WS and DS. Yields were significantly higher when any amount of fertilizer was applied than when none was applied (Table 1). As expected, DS yields were higher than WS yields. More farmers (49%) applied fertilizer in DS than in WS (31 %). Regression of yields for the varieties showed no difference in responsiveness to fertilizers. This was expected because the introduced and almost all of the varieties were IRRI varieties or lines (Kru).

Varieties were also ranked by yield per farm. IR66 was the highest yielder the most times in both WS and DS and the lowest yielder the fewest times. Kru was the highest yielder the fewest times. Farmers’ varieties were the lowest yielders the most times (Table 2). These results indicate that IR66 and IR72 have greater yield stability over different locations than Kru and farmers’ varieties,

Most farmers did not provide evaluations of the tested varieties. They appeared to be optimizing production of their current varieties. Perhaps as a result of this, they had relatively little to offer in terms of evaluation, either negative or positive. The project offered to buy back

The three introduced varieties and the

sesbania GM, irrespective of depth.

between fallow and FYM treatments (see figure), but it increased significantly over the fallow treatment with summer mung and sesbania GM. Water-stable aggregates larger than 2 mm were significantly more in FYM treatment; those of smaller size (<0.5 mm) were significantly more in the sesbania treatment (see table).

Continuous application of GM improves the physical properties of soils in a rice - wheat system where soil is puddled before rice is transplanted.

The infiltration rate did not differ

seed produced from the three varieties, but none of the farmers were interested in selling. We observed, however, that seed from the new varieties was being disseminated from farmer to farmer. The apparent greater stability of IR66 and IR72 was expected to be attractive to farmers.

In the short run, constraints to farmers’ use of fertilizers need to be further examined. Farmers not currently using any would clearly increase their yields by using fertilizer.

Table 1. Yields of introduced and farmers’ rainfed lowland rice varieties grown with and without fertilizer. Cambodia, 1990 WS and 1991 DS.

Yield a (t/ha)

1990 WS 1991 DS Variety

With Without With Without fertilizer fertilizer fertilizer fertilizer (n = 23) ( n = 52) (n = 19) (n = 20)

IR66 3.5 2.1 5.5 3.9 IR72 KRU 3.0

3.1 2.1 4.9 4.2 2.5 5.0 3.6

Farmers’ 3.0 2.1 4.3 4.1

a Test of means between fertilizer treatments using t -test was significant at 1% for both seasons. Test of means among varieties using DMRT was nonsignificant.

Table 2. Frequency that each introduced and farmer rainfed lowland rice variety ranked first through fourth for yield. Cambodia, 1990 WS and 1991 DS.

1990 WS 1991 DS

1 2 3 4 1 2 3 4

IR66 34 18 17 4 17 10 8 2 IR72 24 21 23 5 13 8 11 3 KRU 6 32 20 15 3 16 10 7 Farmers’ 15 18 21 19 10 7 8 13

Variety

IRRN 17:4 (August 1992) 17

Effects of submergence timing and application of azospirillum and K on direct seeded rice

K. N. Govindasamy, T. Lakshminarayanan, and S. Subramanian, Soil and Water Manage- ment Research Institute (SWRI), Thanjavur-7, India

Farmers who depend on the Cauvery system in Tamil Nadu have been forced to direct seed rice because of frequent delays in receipt of canal water. K has been reported to help plants recover from

moisture stress by maintaining higher leaf expansion rates, higher chlorophyll contents, and stomatal resistance. It also promotes yield stability and increases productivity under moisture stress by synthesizing more proline. Azospirillum increases root proliferation and provides facilities to get through drought conditions by remaining in the root interspace.

We conducted an experiment to find out if K and azospirillum can be used to enhance productivity under restricted water conditions and to what extent submergence can be delayed after seeding.

Table 1. Effect of time of submergence (30, 45, 60 DAS) and application of azospirillum and K on grain yield of direct sown ADT38 rice. Tamil Nadu, India. a

Grain yield (t/ha)

Treat- ment

no.

1 2 3

4 5

Time of K application and azospirillum

inoculation

100% K basal 1 + azospirillum 50% K basal + 25% at tillering + 25% at PI 3 + azospirillum 50% K basal + 50%

Pooled data 1989-90 1990-91 (mean of 2 yr)

30 45 60 Mean 30 45 60 Mean 30 45 60 Mean

5.2 4.8 4.5 4.8 4.6 4.8 4.2 4.6 4.9 4.8 4.4 4.1 6.3 5.2 4.9 5.5 5.5 5.4 4.5 5.1 4.9 5.3 4.7 5.3 4.9 5.2 4.7 4.9 5.0 4.8 3.8 4.6 4.9 5.0 4.2 4.7

6.1 5.7 4.9 5.5 6.1 5.6 4.9 5.5 6.1 5.6 4.9 5.5 5.1 5.0 4.5 4.9 4.8 5.2 4.2 4.7 4.9 5.1 4.3 4.8

at tillering 6 5 + azospirillum 5.6 5.5 4.9 5.3 5.6 5.6 5.1 5.5 5.6 5.6 5.0 5.4 7 50% K basal + 50% 5.2 5.2 4.8 5.1 5.1 4.8 4.9 4.9 5.2 5.0 4.8 5.0

at PI 8 7 + azospirillum 5.9 6.0 5.3 5.7 5.7 5.5 5.4 5.5 5.8 5.7 5.4 5.6

Mean 5.6 5.3 4.8 - 5.3 5.2 4.6 - 5.4 5.3 4.7 -

The soil is sandy loam (Typic Haplustalf), with neutral pH, low available N and K, and medium P. The experiment was laid out in a split-plot design during 1989-90 and 1990-91 monsoon seasons. ADT38 rice was the test variety. The main plot was submerged 30, 45, and 60 d after seeding (DAS) to simulate water receipt from the canal. Subplots were treated with K at different times with and without azospirillum inoculation. Nutrient levels were kept uniform at 150-26-50 kg NPK/ha. Rice received only rain until first submergence, after which it was kept wet.

produced optimum grain yield; further delay in irrigation water reduced yield (Table 1). Azospirillum exhibits an augmentative effect. Applying a split of K-half at seeding, half at panicle initiation (P1)—benefited rice more than when all K was applied as basal or in three splits.

Straw yield followed a similar trend (Table 2).

Farmers can obtain higher productivity in direct seeded rice that is later converted to wet rice by applying irrigation water at 45 DAS, azospirillum inoculation, and K splits basal and at PI.

Submergence at 30 or 45 DAS

SE LSD SE LSD SE LSD Time of submergence 0.1 0.4 0.2 0.5 0.1 0.3 Planting rainfed winter Time of K application 0.1 0.4 0.2 0.5 0.1 0.3 crops in rice fallows under Interaction 0.3 ns 0.3 ns 0.2 ns different N and tillage and azospirillum

treatments a ns = nonsignificant.

Table 2. Effect of time of submergence (30, 45, 60 DAS) and application of azospirillum and K on straw yield of direct sown ADT38 rice.

Straw yield (t/ha) Treat- ment Time of K application and 1989-90 1990-91 no. azospirillum inoculation

30 45 60 Mean 30 45 60 Mean

1 2 3

4 5 6 7 8

100% K basal 5.61 1 + azospirillium 6.36 50% K basal + 25% at tillering + 5.49

25% at PI 3 + azospirillum 6.48 50% K basal + 50% at tillering 5.50 5 + azospirillum 5.98 50% K basal + 50% at PI 5.64 7 + azospirillum 6.32

Mean 5.92

5.23 5.41 5.44

5.98 5.49 5.73 5.56 6.17 5.63

5.02 5.09 5.04

5.30 5.22 5.12 5.16 5.74 5.21

5.29 5.62 5.32

5.92 5.40 5.61 5.46 6.08

5.59 6.43 5.31

6.34 5.42 5.99 5.55 6.29 5.87

5.16 5.39 5.5 1

5.83 5.36 5.62 5.38 6.18 5.56

4.70 5.18 4.86

4.72 5.13

5.03 4.94 5.63 5.02

5.15 5.67 5.73

5.77 5.17 5.55 5.29 6.03

SE LSD SE LSD Time of submergence 0.11 0.37 0.14 0.47 Time of K application and azospirillum 0.11 0.31 0.13 0.37 Interaction 0.19 ns 0.23 ns

N. R. Das and S. Sen, Agronomy Depart- ment, Faculty of Agriculture, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, Nadia 741235, West Bengal, India

We evaluated the productivity and production economics of five winter crops sown in rice fallows under rainfed conditions before and after the harvest of transplanted irrigated rice under two tillage conditions and two N levels. Soil is clayey loam with a pH of 6.8, 0.6% organic C, 0.06% total N, 20 kg available P/ha, and 170 kg available K/ ha. The experiment had 7.5- × 2.0-m plots laid out in a split-split-plot design with four replications. Tillage was in the main plots, crops in subplots, and N in sub-subplots.

18 IRRN 17:4 (August 1992)

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greenhouse. Conspicuous leaf B1 lesions were counted on each plant about 5 d later. We stuck slides coated with gelatin to the lesions to estimate spore production.

On 31 Jan 1991, we observed 100 infected trap plants, each with an average of 5 lesions and a mean sporulation of 110 spores/lesion (see figure). We advised farmers to spray tricyclazole 75% wettable powder in the neighboring fields.

At the booting stage (19 Feb), 80 infected trap plants had a mean sporulation of 80 spores/lesion. We issued the same recommendation to farmers.

By the panicle growth stage (22 Feb), the lesions/plant, spores/lesion, and diseased trap plants were reduced (see

Establishment of rainfed winter crops under different N fertilizer and tillage treatments after wet rice, West Bengal, India, 1989-90. a

Treatment Seedlings Branches Grains 1,000- Grain Straw Net (no./m 2 ) (no./plant) (no./panicle seed

or pod) yield yield return

wt(g) (t/ha) (t/ha) ($/ha)

Crops Lentil 115 9.5 1.6 17.0 0.73 2.71 361 Grasspea 85 7.4 2.4 62.9 1.40 2.83 518 Mustard 303 3.2 2.8 2.1 0.33 1.04 284 Wheat 115 136.7 24.3 37.9 1.30 2.21 249 Beans 28 4.7 2.6 85.7 0.59 2.30 331

Mean 129 32.3 6.8 41.2 0.84 2.23 320 LSD (0.05) 22 5.2 6.7 9.8 0.95 1.04

N level (kg/ha) 0 131 27.6 5.7 38.6 0.73 2.00 281 50 127 31.0 7.8 43.9 0.95 2.46 360

Mean 129 32.3 6.8 41.2 0.84 2.23 320 LSD (0.05) ns 5.1 1.2 5.1 0.07 0.31

Tillage number 0 128 33.8 7.6 40.8 0.88 4 130

0.63 382 30.8 5.9 41.6 0.79 1.82 259

Mean 129 32.3 6.8 41.2 0.84 2.23 320 LSD (0.05) ns ns ns ns ns 0.37

a Basic IR36 rice yielded 4.1 t/ha with net return of US$507/ha.

IR36 rice was transplanted 20 Jul mustard ( Brassica campestris, cv. 1989,21 d after seeding, at 25- × 25-cm RW351), wheat ( Triticum aestivum, cv. spacing with 4 seedlings/hill. We applied UP262), and beans ( Phaseolus vulgaris, 60-30-30 kg NPK/ha at planting. The cv. PDR14) were broadcast seeded over crop was harvested on 31 Oct. the rice crop 1 d before harvest under

Lentil ( Lens culinaris, cv. L-9-12), zero tillage (ZT) conditions. The same grasspea ( Lathyrus sativas, cv. Nirmal), crops were also broadcast seeded on 30

Integrated pest management—diseases

A trap plant method to predict the occurrence of rice blast (BI)

A. Surin, W. Rodjanahusdin, P. Arunyanart, and S. Disthaporn, Rice Disease Branch, Department of Agriculture, Bangkhen, Bangkok 10900, Thailand

B1 caused by Pyricularia oryzae Cav. is a serious rice production constraint. Rice straw and seeds and weeds are primary sources of infection.

system in which weather conditions and aerial spore densities are monitored. We used trap plants in a ricefield to estimate the spore population during Jan 1990-Mar 1991 in Amphoe Seinoi, Noonthaburi figure). By applying the treatment, Province. Rice variety RD23, which is farmers obtained a high grain yield (6.7 t/ highly susceptible to B1, was planted in ha) with a net return of about US$950. five seedling boxes (5 × 10 cm). We These results suggest that trap plants placed 7-d-old RD23 seedlings in the field can be used to predict the occurrence of €or 2-3 d and then brought them into a B1. Rice trap plants should be placed in

Managing B1 requires a forecasting

Nov after conventional tillage (4 times) with bullocks (CT). Seeding rate in kilograms/hectare was 20 for lentil, 30 for grasspea, 6 for mustard, 100 for wheat, and 50 for beans. We broadcast no N or 50 kg N/ha as per treatment 1 d after harvest in ZT and at plowing in CT. With ZT, lentil was harvested on 3 Feb 1990, grasspea on 1 Feb, mustard on 27 Jan, wheat on 7 Feb, and beans on 2 Feb. With CT they were harvested on 15 Feb, 10 Feb, 27 Jan, 7 Feb, and 11 Feb, respectively.

Rainfed winter crops can be established in rice fallows, although yields differ significantly among crops. Grasspea (grain and stover) yielded more than the other crops (see table).

After transplanting irrigated rice, rainfed winter crops yielded more grain and stover under ZT than under CT (see table) because of higher soil moisture and longer growing period. Winter crop grain and straw yields responded significantly to 50 kg N/ha. Grasspea had the highest net return, followed by lentil and beans. N fertilization gave higher net returns than the control, as did ZT compared with CT (see table).

ricefields 2 wk before sowing and then at 30, 55, 65, and 75 d after sowing to monitor disease progress.

Population of P. oryzae and leaf blast incidence at different rice growth stages. DI = disease incidence.

Surveys of disease or insect incidence/ severity in one environment are useful only if the information is related to other variables (e.g., climatic factors, crop intensification, cultivars, management practices, etc.). By itself, information on incidence in one environment does not increase scientific knowledge.

IRRN 17:4 (August 1992) 19

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Sweeping efficiency (%) for N. virescens large nymphs and adults at various rice stages.

Sweep net efficiency as affected by insect stage and sex, pipunculid parasitism, and rice stage

G. N. Astika, N. S. Astika, and K. R. Widra- wan, Food Crop Protection Center VII, P.O. Box 88 Denpasar, Bali; and Y. Suzuki, Directorate of Crop Protection, P.O. Box 7236/JKSPM, Jakarta 12072, Indonesia

Sweeping with an insect net is a common method of assessing green leafhopper (GLH) Nephotettix virescens populations. The interpretation of population parameters based on raw sweeping data, however, may be misleading if sweeping efficiency varies among samples.

We studied the effect of insect stage and sex, pipunculid parasitism, and rice stage on sweeping efficiency for GLH. We made weekly population counts by sweeping and by the Farmcop sampler in 17 ricefields where Krueng Aceh had been transplanted at 3-5 plants/hill, at 25-cm spacing. Sweeping samples were taken using 125 strokes of a 42-cm-diam insect net at 1-12 wk after transplanting (WT). A Farmcop count was made at twenty 4-hill spots in the same fields prior to sweeping.

Sweeping efficiency was calculated as the ratio of sweeping catches/stroke to Farmcop catches/spot. Mean sweeping efficiencies in all of the fields were 0.090

Tungro viruses in volunteer rice plants

E. R. Tiongco, N. G. Fabellar, P. S. Teng, and H. Koganezawa, IRRI

Rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV) reportedly survive in rice stubble, weeds, and wild rice species, which then act as sources for reinfection of succeeding rice crops. We studied whether volunteer rice plants that germinated from seeds spilled after threshing harbor RTBV, RTSV, and tungro vector insects.

We surveyed 5-16 threshing sites used in the 1990 dry season crop in Magarao and Pili, Camarines Sur; Barotac Nuevo, Iloilo; and Isulan, Sultan Kudarat. Sites covered areas of 2-5 ha in tungro endemic fields. Sweep nets were used to determine the

number of tungro vectors in 3- to 4-wk- old volunteer rice plants. Enzyme-linked immunosorbent assay (ELISA) was used to determine the presence of tungro viruses on 10-20 batches of 10 seedlings/ site.

More leafhopper vectors were collected in Sultan Kudarat than in Camarines Sur and Iloilo, although leafhoppers were present at most sampling sites (see table). Camarines Sur samples had no infection.

Low composite infection of RTBV

and RTSV was obtained even though testing the plants in batches increases the chances of detecting double infection. The results indicate that single infection of RTSV is predominant in the field, even in volunteer plants.

Results show that volunteer rice plants are infected by tungro viruses and harbor tungro vectors. They can serve as direct sources of infection and tungro vectors for the succeeding crop, especially in asynchronously planted fields.

Tungro vector density and percentage RTBV and RTSV infection in volunteer rice plants in 3 Philippine provinces, 1990 DS.

Sampling Av vector Batches Batches (no.) of seedlings infected with Location sites density a tested b

(no.) (no.) (no.) RTBV + RTSV (%) RTBV (%) RTSV (%)

Camarines Sur 5 4.4 77 0 0 0 Iloilo 12 2.5 239 3.7 0.4 17.5 Sultan Kudarat 16 19.0 317 4.4 1.9 21.3

a Leafhopper catches per 10 sweeps. b Batches of 10 seedlings were assayed separately by ELISA.

Integrated pest management—insects

Sweeping efficiency for N. virescens adults. a

Efficiency (%) Rice stage Healthy Healthy Healthy Parasitized (WT) mature immature males males and

females females females

1-4 2.48 a 3.84 a 10.93 a 12.74 a 5-8 4.12 b 5.69 b 12.91 b 17.96 ab

9-12 5.87 b 6.94 b 13.74 b 23.11 b

a In a column, means followed by the same letter are not significantly different at the 5% level by Kruskal-Wallis/ Scheffe's multiple range test.

(0.056/0.619) for large nymphs (3d to 5th instar), 0.030 (0.008/0.268) for healthy mature females, 0.055 (0.014/0.253) for healthy immature females, 0.125 (0.044/ 0.353) for healthy males, and 0.182 (0.016/ 0.088) for pipunculid-parasitized males and females. Differences in the mean catches between the two methods were significant (p<0.01 by t-test) for all GLH categories.

Sweeping efficiencies for large nymphs and adults increased as rice grew older (see figure). The difference between these stages was negligible except at 11-12 WT.

Sweeping efficiency differed markedly among categories of adults (see table). Efficiency was highest for GLH parasitized by pipunculids, suggesting that their position in rice plants is, on the average, higher than that of healthy adults.

than males. Among females, sweeping efficiency was consistently lower for those with mature ovaries than for those with immature ovaries; nevertheless, the difference was slight.

These results indicate that sweeping samples give overestimates for population parameters such as pipunculid parasitism, sex ratio (male proportion), percentage of immature females, and population growth rate per generation.

Females were less efficiently collected

20 IRRN 17:4 (August 1992)

Integrated pest management—other pests Rat damage in ricefields under dry field conditions in Madhya Pradesh (MP), India

R. K. Patel, A. K. Awasthi, and O. P. Dubey, All India Co-ordinated Research Project on Rodent Control, Entomology Department, Jawaharlal Nehru Krishi Vishwa Vidyalaya, Jabalpur, MP, India

We surveyed crop losses to rats Bandicota bengalensis (Gray) and Rattus

rattus (Linnaeus) in ricefields under dry farming conditions in Rewa District. Most of the fields had narrow, small bunds and a light soil. Drought conditions prevailed during the wet crop season. IR36 and local varieties Biranjphul, Kabeli, Dhiula, Lohandi, and Dilhansa were broadcast seeded.

We observed 26 fields, each 0.4-1.0 ha, before maturity of the standing crop when soil was completely dry. Two fields per village were selected to record the

number of hills and the healthy/damaged tillers in five randomly selected 1-m 2

samples along a diagonal line/field. Average yield of 100 panicles was

determined at harvest and multiplied by the number of damaged tillers to get the yield loss due to rats.

Rats cut 1.4-7.2 tillers/m2 before the maturity stage of the crop. Yield loss was 1.3-6.7%. Estimated yield loss was 2.33- 12.02 g/m 2 , with a mean of 6.08 g/m2

(60.8 kg/ha).

ANNOUNCEMENTS Call for news

Individuals, institutions, and organizations are requested to inform the editor about upcoming events in rice research or related fields for the Rice Dateline. Send announcements to the Editor, IRRN, International Rice Research Institute, P.O. Box 933, Manila 1099, Philippines.

New publication shortcomings in existing arrangements. Published by World Resources Institute.

Forging international agreement: Order from WRI Publications, P.O. Strengthening inter-governmental Box 4852, Hampden Station, Baltimore, institutions for environment and MD 21211, USA. Telephone: 410-516- development, by Lee A. Kimball. 6963. Highlights the present and future challenges facing the international institutional system and pinpoints the

Rice dateline a

September 5-25

15 Sep- 2 Oct

21-25

28 Sep- 2 Oct

28 Sep- 16 Oct

Main Phase of the 4th External IRRI Review. IRRI. Contact M.F.L. Goon/K.A. Gomez, IRRI.

Development. Delft, The Netherlands. Contact International Institute for Hydraulic and Environmental Engineering, Oude Delft 95, P.O. Box 3015,2601 DA Delft, The Netherlands.

IRRI Board of Trustees Meeting. IRRI. Contact K.J. Lampe, IRRI.

Asian Rice Farming Systems Working Group Meeting. Suweon, Korea. Contact V.R. Carangal/F.A. Bernardo, IRRI.

Senior Advanced Course on Lowland

Effective Irrigation Management Course. University of Southampton, United Kingdom.

Contact Course Administrator, Effective Irrigation Management Short Course, Institute of Irrigation Studies, The University, Southampton SO9 5NH, United Kingdom. Fax: 0703-593017.

October 12-16

15-16

19-23

November 11-13

16-20

25-27

Indo-China Rice Research Meeting. Vientiane, Laos. Contact J.M. Schil1er/V.R. Carangal, IRRI.

Sri Lanka-IRRI Work Plan Meeting. Contact F.A. Bernardo/V.R. Carangal/D. Senadhira, IRRI.

Madagascar Work Plan Meeting. Contact F.A. Bernardo/G.L. Denning, IRRI.

Sri Lanka Work Plan Meeting at IRRI. Contact F.A. Bernardo/D. Senadhira/G.L. Denning, IRRI.

International Workshop on Women in Rice Farming Systems, Chiang Mai, Thailand. Contact V.R. Carangal/T. Paris, IRRI.

Bhutan-IRRI Work Plan Meeting. Contact F.A. Bernardo/G.L. Denning, IRRI.

Address for all IRRI contacts: International Rice Research Institute, P.O. Box 933, Manila 1099, Philippines. Telex: (ITT) 40890 RICE PM. Fax: 63-2-818-2087.

IRRN 17:4 (August 1992) 21

IRRl group training courses for remainder of 1992

The IRRI Training Center offers a variety of courses on rice-related subjects. For information about a course, contact the Head, Training Center, International Rice Research Institute, P.O. Box 933, Manila 1099, Philippines. Fax 63-2-818-2087. Space is available for trainees in these courses:

5 Oct-6 NOV

5 Oct-27 NOV

2-27 NOV

16-27 NOV

16-27 NOV

Rice Seed Health Rice Biotechnology IRRI-UNDP Training Course on Methane Emission from Ricefields:

Gender Analysis and Its Application to Rice-based Farming Systems

IRRI-ISNAR-UPLB Research Management

Principles and Methodologies

Research

NEWS ABOUT RESEARCH COLLABORATION IRRl foresees 21st century rice shortage without more rice research

More than 270 scientists from more than 40 countries attended the 21st International Rice Research Conference held 21-25 April at IRRI in Los Baños, Laguna, Philippines.

“The world continues to need rice research,” said IRRI Director General K. Lampe. “The race to stay ahead of famine in Asia has not yet been won.”

Conference topics included hybrid rice research, pest science and management, and nutrient management. “India, Indonesia, Vietnam, and North Korea were identified as the countries where the availability of labor and the large proportion of irrigated ricelands favor hybrid rice technology,” IRRI Rice Breeder S. Virmani said. He reported the conclusions of scientists who reviewed the current status of hybrid rice production.

“The technology will have moderate impact in Malaysia, Pakistan, Philippines, and Thailand,” said Virmani. Hybrid rices yield 15-20% more than conventional modern varieties.

The group of scientists who discussed pest science and management called for more research on varieties with multiple resistance to insects and diseases.

They also urged that governments adopt a national policy based on integrated pest management concepts,

22 IRRN 17:4 (August 1992)

and review and find alternatives to pesticide support and subsidy schemes.

A third group of scientists looked at rice nutrients and ways to efficiently utilize fertilizers. Nutrient management is

critical to rice production because it takes 1 kg of nitrogen nutrient to produce 15- 20 kg of grain. But a farmer using today’s technologies loses more than half the fertilizer he or she applies.

A BPH-resistant glutinous rice for Lao PDR

Brown planthopper (BPH) infestation is one of the most serious constraints to rice production in Lao PDR. The National Rice Research Program for Lao PDR has been collaborating with the Lao-IRRI Project to counteract this problem. These scientists have been systematically evaluating local and introduced lines to

find suitable glutinous lines for dry season (DS) irrigated production. Modem varieties currently available for DS production are nonglutinous and often are of poor eating quality. IR43069-UBN- 507-3-1-2-2, the result of a cross between an IRRI material and Niaw Sanpahtawng, was singled out for further evaluation and probable release to farmers during the 1992-93 DS.

Seven countries adopted 15 IRRl varieties in 1991

Fifteen’ rice varieties bred by IRRI were released to farmers in seven countries in 1991. This raises to 226 the number of IRRI-bred varieties now planted by farmers worldwide.

Six IRRI-bred varieties were released during the year to Vietnamese farmers. National seed boards recommended two varieties each in Indonesia, Myanmar, and the Philippines, and one each in Brunei, China, and the Dominican Republic.

Breeders in 40 rice-growing countries have developed 1,875 varieties since the

release of IR8 in 1966. Sixty percent of these have an IRRI ancestor in their genealogy.

IRRI, Iranian university sign technical cooperation pact

The University of Guilan (UG) in Rasht, Iran, and IRRI have agreed to collaborate to increase Iran’s rice production.

Dr. A. Varsei, chancellor of UG, and Dr. K. Lampe, IRRI director general, signed a memorandum of agreement for scientific and technical cooperation 2 May at IRRI in Los Baños.

“The 5-year collaboration between IRRI and UG will generally aim to promote rice research, training, and exchange of information and technology,” said Varsei. UG is located in the center of Iran’s largest rice production area.

Under the agreement, selected UG students will conduct thesis research on rice at IRRI. IRRI scientists will work with UG researchers, both in Iran and at IRRI, to develop improved rice varieties and technologies for the irrigated and possibly the upland rice ecosystems of Iran.

“IRRI will also provide technical support in establishing molecular genetics and tissue culture laboratories at UG,” Lampe said.

The UG-IRRI Memorandum of Agreement expands the current scientific collaboration between IRRI and Iran. Under an existing Memorandum of Understanding with the Iranian Ministry of Agriculture and Rural Development, Iranian and IRRI researchers work to increase rice yields and improve rice production technology.

Iran’s rice breeders participate in the International Network for Genetic Evaluation in Rice, to which promising rice lines are submitted for evaluation by

ERRATA

scientists worldwide. Iranian agronomists Network on Soil Fertility and Sustainable share their findings in rice farming Rice Farming. Iranian researchers also systems with rice scientists from other attend nondegree training courses at countries through the International IRRI.

Turkey-IRRI collaboration

Turkey has been a participant in the International Network for Genetic Evaluation of Rice (INGER) since 1979. Seventy-four sets of eight types of INGER nurseries have been tested in Turkey from 1979 to 1991. Three INGER lines—Krosnodarski 424 from USSR, Plovdiv from Bulgaria, and Lieto from Italy—have been released as varieties in Turkey.

INGER’s contact scientists in Turkey are

N. Acikgoz Ege Universitesi Ziraat Fakultesi Tarla Bitkileri Bolumu Bornova, Izmir

Directorate and Coordinator of

Directorate of Agriculture Research

P.O. Box 16 Edirne

B. Kiral

National Rice Project

Institute

Calcutta University uses INGER-developed biochemical screening method

A new biochemical screening method developed at the International Network for Genetic Evaluation of Rice seed science laboratory at IRRI was used at Calcutta University to screen for low temperature tolerance in entries of the preliminary set for the boro nursery, reports D.V. Seshu, global INGER coordinator, after a trip to boro sites in eastern India and Bangladesh last March. The test revealed that entries TTB15-1, TRC246-10, Bir-ze-goo, CR544-1-2, IET10405, and CR544-1-3- 4 have high levels of tolerance for low temperature.

Characteristics of Fe-toxic soils and Assessment of rice resistance and and T.E. Akchurst. 17:3 (Jun 1992), 11-12. affected plants and their correction in susceptibility to stem nematode On p. 11, replace the figure with the acid Haplaquents of Meghalaya, by B.P. Ditylenchus augustus, R.A. Plowright new copy given below. Singh et al. Vol. 17 (2) (April 1992).

delete “India’s.” In line 4 of paragraph 1 on page 18,

Diagrammatic representation of symptoms of D. angustus A: susceptible, with seventy rated 0-16, B = resistant.

IRRN 17:4 (August 1992) 23