international rice research newsletter vol.7 no.4

8/4/2019 International Rice Research Newsletter Vol.7 No.4

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Contents

ENETIC EVALUATION AND UTILIZATION

erall progress

3 Heritability estimates of rice crosses

3 Improved rice variety released in the Philippines

3 Three new rice varieties for Nepal

4 Evaluation of IRTP nurseries

isease resistance

5 Resistance of rice cultivars to Xanthamonas campestris pv. oryzae at

6 Bacterial blight resistance under natural conditions

6 Varietal reaction to natural infection of rice tungro virus in Bihar

7 Identification of stable sources of resistance to blast in Nepal

8 Tainunga 68, the first BPH-resistant japonica cultivar developed in Taiwan

8 Correlations between silvershoots and panicle and tiller numbers

9 Resistance of modern rice varieties to the brown planthopper in Thailand

10 Reaction of rice cultivars to gall midge attack in Orissa

9 Reaction of selected rice varieties to whorl maggot Hyderllia spp.

10 Effect of nitrogen fertilizer levels and spacing on rice gall midge and

11 Influence of planting time on gall midge incidence at Aduthurai

11 Pests of hill rice in West Bengal, India

seedling and adult stages

sect resistance

leaffolder damage

her pests

11 Hirschmanniela oryzae and other nematodes found in rice paddies of the

Mekong Delta, Vietnam

rought resistance

12 Using check varieties to adjust visual scores for nonuniform soil drying in

drought resistance field screening

Adverse soils tolerance

12 Varietal tolerance for acid sulfate soils in North Vietnam

PEST MANAGEMENT AND CONTROL

Diseases

14 Relative humidity and nematode number and survival in rice seeds

14 Fungicidal control of rice grain discoloration

14 Epidemiology of brown spot disease of rice in Karnataka, India

15 Root-knot disease of rice in the Mekong Delta, Vietnam

15 Field soil as a source of rice stem nematodes

Insects

15 Parasite of the rice slug caterpillar

15 Sepedon sphegeus (Fabr.) (Sciomyzidae) and Notiphila spp. (Ep

dae ): alternate hosts of Trichogramma japonicum Ashmead, a ric

borer egg parasite

16 Populations of gall midge, whitebacked planthopper, and thrips on Pr

gati paddy17 Effects of silica level on whitebacked planthopper

17 Disruption of striped rice borer males orientation to pheromone t

SOIL AND CROP MANAGEMENT

18 Nitrogen management in flooded rice

18 Effect of seedling age an susceptibility to aluminum toxicity

18 Algae in rice fields of Chingleput District, Tamil Nadu, India

19 Comparison of zinc sulfate and Zn-EDTA as foliar spray

ANNOUNCEMENT

20 New rice publication


3/20

Heritability estimates of rice crosses

B. K. Mandal, Rice Research Station, Chin-

surah, West Bengal, India

Heritability estimates of nine quantita-

tive characters were made using a half-

diallel cross involving seven parents: Sel.

ADT 27, Kataktara, ADT27. Padma,

IR8, TN1, and NC1626. The formula

used was: (D + H1 - H2 - F);

(D + H1 - H2 - F+ E).

The estimates show that the major

part of the total phenotypic variation for

plant height, grain-weight, length, and

breadth is due to additive genetic effects

(see table). Low estimates for effective

tillers, ear length, duration. grain yield,

and grain number indicate the influence

of nonadditive gene action in the expres-

sion of these characters.

Significant epistatic effects were

detected when genetic components were

analyzed for duration in crosses involv-

ing Sel. ADT27 or ADT27 as one par-

ent. By eliminating the arrays of crosses

of these two parents, the narrow sense

heritability was 78.4%, against 28.4% in

the presence of epistasis. This shows that

nonadditive gene action with epistasis

distorts the heritability estimate.

Selection for characters such as plant

height and grain weight may be done in

the early generation. Selection for char-

acters with low heritability, such as

effective tillers, ear length, duration,

grain yield, and grain number, should be

deferred till plants reach

homozygosity.

Improved rice variety released in the

Philippines

International Rice Research Institute

The Philippine Seed Board approved the

release of IR56 on 10 June 1982. IR56

was the selection IR13429-105-2-2-1

from the cross IR4432-53-3-3/Ptb 331//

IR36 made in 1976.

IR56 had superior performance in

lowland cooperative trials during 1980and 1981. Its yield potential is compara-

ble to that of IR36; it matures in 105

days. 2-3 days earlier than IR36; it has

long, slender, translucent grains with

high amylose and low gelatinization

temperature, and high milling recovery.

IR56 is resistant to all major diseases

and insects: blast, bacterial blight,

tungro, grassy stunt, green leafhopper,

and three biotypes of brown planthop-

per. Its resistance to tungro is higher

than that of IR36. In field trials in Min-

danao, IR56 showed tolerance for

ragged stunt virus. Its gene for resistance

to brown planthopper and green leaf-

hopper are different from those of IR36,

thus diversifying the genetic base of

improved materials being grown in

Asia.

Three new rice varieties for Nepal

K. P. Shrestha, agronomist, B. R. Akhikary,

assistant rice breeder, B. B. Shahi, and

S. Samoto, rice coordinators, National Rice

lmprovement Program, P.O. Box 4, Birganj,

Nepal

Through collaborative testing by the

International Rice Testing Program and

the national rice improvement program,

^ ^

^

^

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^

Guidelines and Style

^

forIRRN Contributors

To improve communication and to speed theeditorial process. the editors of the International

Rice Research Newsletther (IRRN) request thatcontributors use the following guidelines and style:

Style

national units of measure (such as cavans, rai. etc. ).

Use the metric system in all papers Avoid

with small-scale studies, in grams per pot (g/pot) or

Express all yields in tons per hectare (t/ha) or,

grams per row (g/row).

or symbols used in a figure or table.

chemicals near the unit of measure. For example:

60 kg N/ha; not 60 kg/ha N.

the IRRN. Data in other currencies should beconverted to US$.

Abbreviate names of standard units of measurewhen they follow a number. For example 20 kg ha.

When using abbreviations other than for units ofmeasure. spell out the full name the first time ofreference, with abbreviations in parenthesis, then use

example: The efficiency of nitrogen (N) use wasthe abbreviation throughout the remaining text. For

tested. Three Ievels of N were .... or Biotypes of the

studied the biotypes of BPH in ....

brown planthopper (BPH) differ within Asia. We

number, even when the amount is less than 10. For

Express time, money, and measurement in

example: 8 years; 3 kg ha at 2-week intervals; 7%;

4 hours.

Write out numbers below 10 except in a series

containing some numbers 10 or higher and some

seven tractors: four varieties. But There were 4 plotsnumbers lower than 10. For example: six parts:

in India, 8 plots in Thailand, and 12 plots inIndonesia.

Write out all numbers that start sentences. Forexample: Sixty insects were added to each cage:Seventy-five percent of the yield increase is attributedto fertilizer use.

Guidelines

Define in footnotes or legends any abbreviations

Place the name or denotation of compounds or

The US dollar is the standard monetary unit for

Contributions to the IRRN should generally be

patterns involving rice. based on results of research on rice or on cropping

Appropriate statistical analyses are required formost data.

Contributions should not exceed two pages ofdouble-spaced, typewritten text. Two figures (graphs,

supplement the text. The editor will return articlestables, or photos) per contribution are permitted to

that exceed space limitations.

discouraged. Exceptions will be made only if Results of routine screening of rice cultivars are

screening reveals previously unreported information(for example, a new source of genetic resistance torice pests).

varieties are encouraged.

commercial chemicals and, when feasible, equipment.

contributions.

infection, degree of severity, etc.).

Announcements of the release of new rice

Use common not trade names for

Do not include references in IRRN

Pest surveys should be quantified with data (%

Genetic evaluation and utilizationOVERALL PROGRESS

Estimates of narrow-sense heritability of 9

characters in rice crosses at Chinsurah RiceResearch Station, West Bengal, India.

Narrow-sense

(%)

Character heritability

Plant heightEffective tillers

Far lengthDuration

51.425.624.628.4

Grain yield 38.4Grain number 19.8Grain weight 76.4

Grain length 86.6

Grain breadth 61.0

IRRN 7:4 (August 1982) 3

^^


4/20

Agronomic characteristics of newly released varieties in Nepal.

VarietiesAgronomic characteristic

Kanchan(IR3941) (IR2298)

Himali Taichung 176 Malika CH-45 Laxmi

(check) (Mala/J 15) (check) (check)

Days to headingDays to maturityPlant height (cm)

Panicle length (cm)Panicle no./m2

No. of filled grains/panicleFertility (%)1,000-grain wt (g)Straw wt (t/ha)Blast reactionUnhusked length (mm)Unhusked width (mm)Shape% of husking% of milling

Appearance of polished rice

Av yieldTesting station

103143

68

21400

818222.1

5.81R9.63.4

Slender/long78.3772.50

High/trans.

7.60Khumaltar

Kathmandu

110145

61

22275

919126.9

5.38R

10.33.4

Slender75.2272.00

High/trans.

7.18Khumaltar

Kathmandu

10314884

21265

907824.5

6.07S7.83.5

Medium/short80.2276.00

Medium/low

with white belly6.40

KhumaltarKathmandu

90120119

3051088521.3

S

22.3

8.52.8

Slender/med.78.172.4

High/trans.

4.9Parwanipur

8511512426.0

340738825.0

R

8.92.9


Coarse withwhite belly

Parwanipur4.3

951259521 .0

405738924.9

R

9.22.9


Medium witwhite belly

4.58Parwanipur

Nepal, three rice varieties were released

for general cultivation by the national

seed recommendation committee of

Nepal in 1982 (see table). IR3941-4-

which was named Kanchan, and

which was named Himali, are recom-

mended for temperate regions up to

PLP2B (CR126-42-5/IR2061-213),

1R2298-PLPB-3-2-1-1 B (CICA 4/ Kulu),

1,500 m altitude. Mala/J15 (CP-

SL02/ Sigadis), which was named Mal-

ika, is suitable as an early crop in irri-

gated areas and a monsoon season crop

in rainfed tropical areas.

and blast resistant. They have early

maturity and good eating quality and

are easily threshable. They are as non-

Kanchan and Himali are high yielding

lodging as the Taiwanese varieties grow

in the Kathmandu valley and in areas o

similar climates in temperate Nepal.

Himali is an aromatic variety with good

market value.

Malika is early and resistant to lodg-

ing. It has high seed dormancy during

rainy season harvesting, bacterial blight

resistance, and good grain quality.

Evaluation of IRTP nurseries

L. S. Mani, W. Wilfred Manuel, K. Gane-

san, and L. Anavaradham, Paddy Experi-

ment Station, Ambasamudram 627401,

Tamil Nadu, India

Two trials International Rice Obser-

vational Nursery (IRON) and the Inter-

national Rainfed Lowland Rice Obser-

vational Nursery (IRLRON) were

conducted during 1981 kar (Jun-Nov).

The nonreplicated observational plots

were not protected from pests and dis-

eases. For IRON, 242 genetically diverse

entries and 5 checks were screened. For

IRLRON, 128 entries (38 early and 90

late duration) and 7 checks were evalu-

ated. Cultivars were sown on 18 June

1981 and transplanted on 17 July. Plot

sizes were 3.25 m 0.75 m with 25-

25-cm spacing, 1 seedling/ hill. The fertil-

izer schedule was 100-50-50 kg

N-P2O5-K2O/ha.

For IRON, IR13540-56-3-2-1 (R.

Table 1. Performance of promising entries from the 8th IRON, Tamil Nadu, India.

Designation

EntryIR9763-11-2-2-3IR9830-26-3-3IR13525-43-2-3-1-3-2

IR15529-256-1IR17525-278-1-1-2IR19588-162-1

343 DTBKNBR 1031-7-5-4BR161-2B-54B2791-B-MR-145-1B3063-B-TK-72-2

Chianung Si-Pi. 661020IR5657-33-2-2-3IR9217-6-2-2-2-3IRl3149-71-3-2IR19661-293-1-3-2IR19670-57-1-1-3Kaohsiung Sen Yu 104

MTU 7029OR47-2 (Jajati)OR131-3-1RP 1057-184-5-3-3

R 35-2874

Suakoko 8(2526)X 2-D T

Grain yield

(t/ha)

5.57.05.75.5

5.76.2

6.25.7

6.65.56.0

5.56.46.15.95.57.05.96.67.4

6.65.5

6.46.05.9

% overADT36

(local check)

100.0127.3103.6100.0103.6112.7112.7

103.6120.0100.0109.1

100.0116.4110.9107.3100.0127.3107.3120.0134.5

120.0100.0

116.4109.1

107.3

Floweringduration

(days)

Plant ht

(cm)

1051039695

104105

95105

99

105103

9898

95105

989795

10595

100125

95100

95

94838984

8692

100

14687

131110

93108110108

96103104105122

88

11695

13492

CONTINUED ON OPPOSITE PAGE

4 IRRN 7:4 (August 1982)


5/20

Table 1 continued

Grain yield% over Flowering

Designation ADT36 durationPlant ht

(cm)(t/ha) (local check) (days)

Chianung Sen Yu 13IR13540-56-3-2-1

RP825-45-1-3

CheckIR36

IR42IR1552ADT36 (local)

BR10(BR51-46-5)

5.97.8

6.2

3.03.93.3

1.45.5

Mean (m) 4.2Std. deviation 1.2m 5.4

107.3141.811 2.7

54.570.960.0

25.5100.0

76.421.898.2

9691

100

951041069896

94

7584

82105

8283

101

Table 2. Performance of promising entries from the 4th IRLRON, Tamil Nadu, India.

DesignationGrain yield

% of Flowering

Pelita I-1(t/ha) (local check)

duration(days)

Plant ht

(cm)

EntryBR10(BR51-46-5) 4.8 123.1 99 113

IR13146-45-2 5.5 141.0 96 121

IR13505-30-B-3 4.8 123.1 89 86

IR4744-295-2-3 4.7 120.5 92 87

IR5873-9-1 5.0 128.2 89 106

IR9763-11-2-2-3 4.7 120.5 99 106

BIET927 (RAU 38-12-3-1) 4.5 115.4 123 146

BKN6990-63 5.0 128.2 119 157

BR111-140-1-1 4.5 115.4 114 148

CR1030 6.4 164.1 116 151

C424-2 4.5 115.4 106 124

IR13365-253-3-2 4.5 115.4 117 111

IR13564-109-1 4.7 120.5 116 100

IR14632-65-2 4.5 115.4 116 112

IR14875-98-5 4.5 115.4 113 104

IR19083-22

-2-2 4.5 115.4 118 104

IR19431-72-2 5.4 138.5 103 94

IR3646-9-1-1 4.8 123.1 99 132

IR4819-77-3-2 5.4 138.5 106 133

IR4829-89-2 4.8 123.1 112 115

IR5857-64-IE-1-6 4.7 120.5 110 108

IR7545-27-3-2 4.7 120.5 106 100

IR9217-6-2-2-2-3 5.7 146.2 105 116

IR9763-11-2-2-3 4.5 115.4 106 109

KAU 2039 4.7 120.5 104 128

MR24 4.5 115.4 98 108

CheckIR36 3.6 92.3 87 76

Cisadane 3.6 92.3 105 108

Mashuri 2.9 74.4 107 139

IR46 2.7 69.2 115 93

IR1552 1.6 41.0 105 75

IR20 2.9 74.4 98 127Pelita I-1 (local) 3.9 100.0 103 114

Mean (m) 3.4 87.2

Std. deviation 1.1 28.2

m + 4.5 115.4

The International Rice Research Newsletter (IRRN) invites all scientists to contribute concise summaries ofsignificant rice research for publication. Contributions should be limited to one or two pages and no more thantwo short tables, figures, or photographs. Contributions are subject to editing and abridgement to meet space

limitations. Authors will be identified by name, title, and research organization.

Heenati/IR30(BPHS)//IR2823-399-5)

had the highest yield (7.8 t/ha in 121

days), 41.8% more than the local check

(Table 1). Yields of 30 other entries and

ADT36 ranged from 5.4 to 7.0 t/ha.

For IRLRON, CR1030 (Waikoku/

CR 1014-211) had the highest yield

(6.4 t/ha in 146 days), 64.1% more thanthe best check (Table 2). Yields of 24

other entries ranged from 4.5 to

5.5 t/ha.

season was whorl maggot, within a

threshold level of 20%. There was no

disease incidence. Based on grain yield

and ancillary characters, 28 entries from

IRON and 3 entries from IRLRON, all

of medium duration, have been selected

for further testing.

The only insect observed during the

GENETIC EVALUATION AND UTILIZATIO

Disease

resistance

Resistance of rice cultivars toXan-

thomonas campestris pv. oryzae at

seedling and adult stages

S. C. Sharma, R. G. Saini, and A. K. Gupta,

Genetics Department, Punjab AgriculturalUniversity, Ludhiana, India

The clipping method was used to inocu-

late 20-day-old seedlings of 428 cultivars

with a highly virulent isolate ofXan-

thomonas campestris pv. oryzae. Aver-

age lesion lengths of the seedling leaves

were recorded 15 days after inoculation.

Adult stage damage was rated on the

standard evaluation scale for rice (0-4

resistant and 4.1-9 susceptible).

Thirteen cultivars showed resistance

at both seedling and adult stages (seetable). Cultivars carrying Xa 1, Xa 2, X

3, and xa 5 were resistant at seedling as

well as the adult stage. IR20 carrying the

gene Xa 4 was susceptible at both

stages.

the seedling stage only ARC 6172,

ARC 6181, ARC 6615, ARC 7251, B-

Some cultivars showed resistance at

76, IR15529-26-1-1-2, IR15529-253-2-2-

2, NCS-2003, NCS 2014, NCS 2039,



6/20

NCS 2041, NCS 2043, NCS 2044, NCS

2046, NCS 2048, NCS 2049, NCS 2055,

NCS 2057, NCS 2072, NCS 2107, and

Palman 579. Lesion lengths ranged from

2.2 cm to 3.6 cm. Some cultivars were

susceptible as seedlings but resistant at

adult stage ARC 5913, ARC 5938,

ARC 5951, ARC 6248, ARC 10602,ARC 11281, Denga Faram, IR2035-117-

3, IR15705-199-3-3, Jhinwa, Jikkoku/

Serpheke chil 52-102, Mudgo, NCS 320,

NCS 332, NCS 338, NCS 335, NCS

2015, NCS 201 8, Sinna Sivappu,

T 1426, Vallathil Cheera, and Vellai

Langayan. Disease scores ranged from

2.2 to 3.8.

Disease reaction of some rice stocks at seedling and at adult plant stage at Punjab, India.

Lesion length (cm) Scores at

Mean Range (0-9 scale

Stock or cultivar Source at seedling stage adult stag

MTUl5/Waiseakokku-127 CRRI 3.65 2.0-7.0 2.7ARC6044 CRRI 3.75 2.5-5.0 4.0ARC11321 CRRI 3.68 2.0-6.0 3.4ARC11367 CRRI 2.75 2.0-4.5 2.2IET6123 CRRI 3.40 2.5-4.5 3.4

NCS2001 CRRI 3.50 1.5-5.0 3.0 NCS2009 CRRI 1.43 0.5-2.5 3.2 NCS2039 CRRI 2.48 2.0-3.5 3.7 NCS1604 CRRI 3.98 2.0-8.0 3.4Kogyoku (Xa 1) IRRI 1.50 1.0-2.0 0.8Tetep ( Xa 1 + Xa 2) IRRI 1.20 0.5-2.5 1.4

Wau Qikoku-3 ( Xa 3) IRRI 2.23 1.0-4.5 1.7

IR1545-339 ( xa 5) IRRI 2.95 2.0-4.5 1.3IR20 ( Xa 4) IRRI 4.78 3.0-7.0 5.6TN1 (susceptible check) 16.68 8.5-26.5 6.5

Bacterial blight resistance under During the 1980 and 1981 wet seasons,

natural conditions bacterial blight appeared in epidemic

form in several pockets of the Chhatis-

R. K. Sahu, junior breeder, M. N. Shrivas- garh region. During the high natural

tava, rice breeder, V. N. Sahu and B. P. infection in 1981, germplasm accessions

Chaudhary, junior breeders, and P. S. Shri- of early and medium duration were

vastava, professor of plant breeding, Zonal screened for resistance, using the Stand-

Agricultural Research Station, J. N. Agricul- ard Evaluation System for Rice scale.

tural University, Raipur, 492006, M. P., Of 6,129 cultivars screened, only 1India scored 1, 24 scored 3, and the others 5-9

Table 1. Resistance of germplasm accessions of rice of different maturities for natural bacterial

blight epidemic in Raipur, M.P. India.

Maturity group

Accessions (no.) with given bacterial blight

screened resistancea score

(no.) 1 3 5 7 9

Extra early (up to 90 days) 558 0 0 14 122 422

Very early (91 to 110 days) 496 0 3 57 138 298

Early (1 11 to 125 days) 2313 1 11 205 833 1263

Medium (126 to 140 days) 2762 0 10 744 1058 950

Total 6129 1 24 1020 2151 2933

aStandard Evaluation System for Rice, % hills affected: 1 = less than 1%, 3 = 1 -5%, 5 = 6-25%, 7 =

26-50%, 9 = 51-100%.

(Table 1). No seed could be harvested

from several highly susceptible lines. No

very early variety was resistant.

The 25 cultivars with scores of 1 and

3 (Table 2) have been selected for

further tests under artificial inoculation

They have also been crossed with varie-

ties carrying known resistance genes to

study their allelic relationship.

Table 2. Bacterial blight-resistant varieties atRaipur, M.P., India.

Karhani KechanaBenikath KhurabanBhatapyagi Liktimati

Badshahbhog RuingiBhatagunda RotadChingerchopa Rageem 14Chinee Kapoor Safed jeeraDilbaksa SatakaGotaka SLOJalkesar Tikurdhan

Kesariya VishnubhogKosma X 11Kariyakora

Varietal reaction to natural infection Table 1. Varietal reaction to rice tungro virus at Bihar, India.

of rice tungro virus in Bihar Resistancescorea

Released varieties Promising varieties

B. N. Singh, senior rice breeder, Y. Prasad,

assistant rice pathologist, and S. P. Sahu,

assistant research officer (rice breeding), BR9, Katarni, IR20 Rajendra Agricultural University, Bihar,

Pusa 848125, India

3 Pusa 2-21, CR44-35 (Saket 4) Pusa 33, TCA4, TCA177Ratna, BR34, Janaki (64-117),

5 Rajendra Dhan 201 TCA80-4, IET6263, RP1045-403-1

7 Rasi (IET1444), BR14, BR8, BIET927, BIET1107, IET5656, ET5882,

Rice tungro virus infection under natu-

ral conditions was very high during

1980-81 kharif. The disease appeared the

first week of August in transplanted

Taichung Native 1 in a dryland field and


Type 3, Pankaj, Sita, PR106 FH132

Prasad, Bala, Cauvery, TCA62-68, TCA62-10, BIET1048,

NC1626, Improved SOna BIET821, IET2707, CRMS37, IET5883,

9 Jaya, IR8, Mahsuri, BR46, UPR82-1-7, IET6155, BIET724, BG90-2,

IET5890, IET6314, IET5897, IET6212

a1980 Standard Evaluation System for Rice scale of 0-9: 3 = 6-10% incidence, 9 = 81-100%.

Accessions


7/20

Table 2. PVT3 and PVT4 entries with resistanc

to rice tungro virus at Bihar, India.

Scorea Cultivars

1 RP1125-1526-2-1-1, RP1125-1526-2-2-3, RP1125-1526-3-2-4, RP1125-

1528-1-4-3

3 CR161-42-16, CR186-1, CR236-63,

CR276-5, RP1064-14-2-4, IR42,R8-2535, P837, P858, SKL6,Pusa 2-21

5 CR98-7216-CRP 34, CR149-9177-CRRP-19, CR188-10, RP974-29-3-2, RP1045-211-7-3-4, RP1064-

14-2-3, RP1091-24, UPR243-63-1,

AD9408, AD77496, P835, PY-1,

Sonalee, RSB40

a1980 Standard Evaluation System for Ricescale of 0-9: 1 = less than 1% incidence, 5 = 21-

30%.

in transplanted Bhutahi in a deepwater

field. Vector green leafhopperNephotet-

tix virescens populations had been in-

creasing during July. The disease later

spread to varietal demonstration plots

and other yield evaluation trials. The

disease diagnosis was confirmed by the

virologist, Central Rice Research Insti-

tute, Cuttack.

No control measures were taken. Dis-

ease incidence was so severe that yields

from some varieties were very low.

Released and promising varieties were

scored for resistance to tungro according

to the Standard Evaluation System for

Rice (Table 1).

In the All India Coordinated Rice

Improvement Program, severe infection

occurred in 2 trials, PVT3 and PVT4

with 128 entries grown in 2 replicationsin each trial. Four entries from the

RP1125 cross (RPW6-13/Ptb 2) showed

resistance, another 11 showed moderate

resistance, and 15 were intermediate

(Table 2). All others were susceptible to

highly susceptible.

Tungro reappeared at Pusa and Patna

during 1981-82 kharif.

Varietal recommendations for North

and South Bihar, where tungro occur-

rence is becoming a problem, have been

changed. Depending upon land situa-

tions, the newly recommended varieties

are Pusa 2-21 and CR44-35 for dryland

transplanting, Ratna and Rajendra

Dhan 201 for midland transplanting,

BR34 for wetland rainfed, and Janaki

for semideep water.

Few resistant lines are available for

wetland irrigated fields. Two lines.

IET6263 (CR262-19) and RP1045-403,

have been found promising. ResistantBR9 and Katarni fragrant, short-

slender, photoperiod-sensitive rices

Identification of stable sources of

resistance to blast in Nepalthe Kathmandu valley and in other hilly

regions of Nepal, have resulted in blast

may be recommended. Type 3, the onlyvariety recommended for export, has

been found susceptible to tungro.

and in lines derived from crosses with

them. Blast reactions were scored

B. P. Upadhyay, assistant plant pathologist, becoming a major source of yield losses. according to the Standard Evaluation

It has been possible to identify blast- System for Rice.and B. B. Shahi, national rice coordinator,

National Rice Improvement Program, Bir- resistant sources by using IRRI mass-

ganj, Nepal screening techniques (see table). These

lines are used extensively in Nepalese

Use of modern Taiwanese ponlai varie- rice breeding programs. During 1977-81,

ties and high doses of nitrogen fertilizer, high levels of blast resistance were found particularly in the temperate region of in cultivars Tetep, Dawn, and Carreon

Individuals, organizations, and media

who wish additional details of

information presented in IRRN should

write directly to the authors.

Highly resistant entries observed in blast nurseries at 2 sites in Nepal.

Blast scorea

Cultivar or lineSource

Khumaltar (1,327 m alt)of resistance

Parwanipur (100 m alt)

1977 1978 1979 1980 1981 1977 1978 1979 1980 1981

CIAT-ICA 5 TetepIR1544-238-2-3 Tetep

IR1416-128-5-8 TetepIR1416-1-42-2-3-3 TetepIR1905-PP11-29-4-61 TetepIR1905-81-3-1 TetepIR3259-5-160-3 Tetep

74-5461 TetepIR5533-56-1-12 Tetep, CarreonIR5533-PP850-1 Tetep, CarreonIR5533-PP854-1 Tetep, Carreon

IR9660-00948-1 DawnTetep (check)

Carreon (check)

Dawn (check)

Sankharika (susceptible check)Pokhareli Masino (local resistant)Chainan 2 (commercial)Chainung 242 (commercial)Taichung 176 (commercial)

111112

1

21112

b1

4

92888

111112

2

1111

14

1

192

779

000b

0

0

b0bb

b

0

0092555

32

1132

2

b13

12

11b

9164

7

0000

000

0000

00

02

93688

1111114

132

3

14

bc

91344

11

111

11

111

1

11

1192113

12

b1

2

5b

b

b3

bb

154

92331

c

1

111

b

1

511

1

1

b3

9

0444

c

00cc

00

0

30000

0

1491556

a Standard Evaluation System for Rice: 0 = no lesions, 9 = all leaves dead. bEntry not used. cMissing.


b


8/20

GENETIC EVALUATION AND UTILIZATION

Insect resistance

Tainung 68, the first BPH-resistant Table 1. Resistancea to disease and insect pest of Tainung 68 in Taiwan, China.

Japonica cultivar developed inTaiwan Cultivar Blast

Neck Bacterial Brown planthopperb

blast blight15 DS 45 DS

W. L. Chang, Chiayi Agricultural Experi- Tainung 68 MR-S MR-S MR-S S R

ment Station, TARI, Chiayi, Taiwan, ChinaTainung 67 (check) S-HS S-HS MS S S

aR = resistant, MR = moderately resistant, S = susceptible, HS = highly susceptible. bDS = days afte

Japonica cultivars, which occupy more seeding.

than 90% of the planted area in Taiwan,

are susceptible to brown planthopper

(BPH). Efforts to transfer BPH resist-

ance from indica to japonica rices have

resulted in the release of BPH-resistant

selection Chianung 250, the first BPH-

resistant japonica cultivar developed inTaiwan. The Subcommittee on Varietal

Registration of the Taiwan Rice

Improvement Council unanimously

recommended its release 1 June 1982.

The new cultivar, officially named

Tainung 68, was selected in 1976 from

the cross Nankai-yu 114/// Nankai-yu

77//Tainan 52/ASD 7, made in 1973 at

Chiayi Agricultural Experiment Station.

The resistance to BPH inherited from

Correlations between silvershootsand panicle and tiller numbers

Prem Chand and R. C. Acharya, Ranchi

Agricultural College, Kanke, Bihar, India

834006

Gall midge infestation is thought to

stimulate profuse tillering. Therefore the

association among silvershoots and

tiller and panicle numbers was assessed.

Data on the three attributes were taken

on variety Sita on 27 randomly selected

hills from each of 11 plots, 10 treated

with insecticides and 1 untreated. Datawere collected after the emergence of

panicles, about 1 month after insecti-

cides were applied.

Total correlation coefficients between

silvershoots and tillers, silvershoots and

panicles, and tillers and panicles and

partial correlation between silvershoots

and panicles were determined. Estimates

of total and partial correlation coeffi-

cients for the 11 treatments were pooled


Table 2. Agronomic performance of Tainung 68 in Taiwan, China (av of 1979-81).

Maturity (days) Height (cm) Yielda (t/ha)

1st 2d 1st 2d 1st 2dcrop crop crop crop crop cro

Cultivar

Tainung 68 115 97 94 99 6.3 4.Tainung 67 (check) 116 98 96 103 6.8 4.

aRecorded at Pintung, southern Taiwan.

ASD7 is expressed at late growing Currently grown cultivar Tainung 67

stages. Tainung 68 also has some resist- is susceptible to BPH, which occurs

ance to blast and bacterial leaf blight severely in southern Taiwan during the

diseases (Table 1). Most agronomic hot, wet second crop season. Tainung 6

characters are desirable, with good is a promising alternative and an impor

yields in the second crop, particularly in tant source of BPH resistance in breed-

the southern part of the island (Table 2). ing programs.

using a multiple covariance model.Tillering correlated positively with sil-

vershoots (see table). Estimates of corre-

lation coefficients varied from 0.1326 to

0.8402, significant in 9 cases. The pooled

correlation coefficient was 0.4718, signif-

icant at the 0.01 level.

Tillers correlated positively with pani-

cles. Estimates of coefficients variedfrom 0.1731 to 0.6898, significant in 9

cases. Estimate of the pooled correlatio

coefficient (0.5518) was significant at th

0.01 level.

Of 11 estimates of the correlation

coefficient between silvershoots and pan

icles, only one was significant. This sug

Estimates of total and partial correlation coefficientsa between silvershoots, tillers, and panicle

numbers at Bihar. India.

Treatment r12 r23 r13 r13 2

Foratox 0.8402** 0.6056** 0.0880ns 0.9751**

BPMC 0.1326ns 0.5227** 0.0096ns 0.0936nsEkalux 0.4002* 0.6898** 0.1438

ns 0.3536*

Carbofuran 0.5604** 0.3551ns

0.2573 ns 0.5608**

Carbaryl 0.7960** 0.1731ns 0.0828 ns 0.6428**

Lindane 0.4099* 0.5548** 0.2604ns 0.6428**

Diazinon 0.6723** 0.5035** 0.4743* 0.2125ns

Tamaron 0.3408ns 0.6370** 0.2242ns 0.6089**

CFVP 0.5467** 0.5563** 0.2653ns 0.2444ns

Monocil 0.5467** 0.5563** 0.2095ns 0.7381**

Control 0.5581** 0.4650* 0.0937ns 0.2257ns

Pooled 0.4718** 0.5518** 0.0029 0.3156*

a l = silvershoots, 2 = tillers, 3 = panicles. * = significant at 5% level. ** = significant at 1% level. ns

not significant.


9/20

gests no association between the two

characters. The pooled estimate was also

nonsignificant.

The absence of correlation between

silvershoots and panicles and the signifi-

cant correlation between silvershoots

and tillering support the popular belief

that silvershoots increase tillering, com-

pensating for panicle loss. But it also

may be argued that a hill containing a

greater number of tillers is more sus-

ceptible to gall midge attack, because it

provides more points. As such, more

tillers would be the cause of silvershoots.

Estimates of partial correlation coeffi-

cients between silvershoots and panicles

after eliminating the effect of tiller dif-

ferences were made. All estimates except

one were negative, varying from 0.9751

to -0.0936 and significant in 5 cases. The

only positive estimate was also small

and nonsignificant. The pooled estimate

of the partial correlation coefficient was

0.3156, significant at the 0.05 level.

A partial regression analysis using the

covariance model y = f(Tr,; X1 X2 X3 )

wherey stands for panicle, X1 for silver-

shoot, and X2 for tiller estimated the

loss due to silvershoots for the pooled

data. The result wasy = 1.84 0.3975

X1 + 0.4584 X2 . The estimate ofR, the

multiple correlation coefficient, was

0.7791, significant at the 0.01 level. Both

partial regression coefficients were also

significant at 0.01. The partial regression

equation suggests that the expected net

effect of a unit increase in the number of

silvershoots is a drop of 0.4 in the

number of panicles.

Resistance of modern rice varieties

to the brown planthopper in

Thailand

Nipha Chansrisommai, Rice Insect Pest

Branch, Entomology and Zoology Division,Department of Agriculture, Bangkhen,

Bangkok, Thailand; and Weerawooth Katan-

yukul, Entomology Department, Interna-

tional Rice Research Institute

Outbreaks of the brown planthopper

(BPH) Nilaparvata lugens have caused a

rapid spread of ragged stunt disease in

the central Thailand plain since 1973.

But RD9, the first BPH-resistant variety

released in 1975, has not been widely

accepted because of its susceptibility to

many diseases and its poor grain quality.A greenhouse experiment was

designed to determine the resistance

mechanism in three varieties released in

1981 RD21 (DML 105/Nang-Mol

S-4//IR26), RD23 (RD7/IR32//RD1),

and RD25 (DML 105/IR2061-214-2-3-3

// DML l05/IR26) and in an RD7

mutant developed by gamma-irradiation

which had shown BPH resistance.

Experimental procedures were those

used in the International Brown Plant-

hopper Biotype Collaborative Project.

A free-choice feeding experimentshowed no significant difference in the

number of insects feeding on resistant

and susceptible varieties. Antibiosis was

indicated: BPH survival after 12 days

was 6% on RD21, 7.5% on RD7

mutant, 14% on RD9, 20% on RD23,

20% on RD25, and 36% on RD1 (Fig.

1). The population buildup study also

confirmed antibiosis reaction in RD21,

RD23, RD25, and RD7 mutant. RD25

1. Survival of brown planthopper on modern rice

varieties in Thailand.

2. Population buildup of brown planthopper(BPH) on different rice varieties 4 weeks afterrelease of 3 pairs of adults, Thailand.

showed the highest resistance (no popu-

lation increase) to BPH; RD1 produced

247 insects 4 weeks after release of 3

mated BPH pairs (Fig. 2).

Reaction of selected rice varieties to

whorl maggot Hydrellia spp.

S. Uthamasamy and P. Karuppuchamy,

Tamil Nadu Rice Research Institute,

Aduthurai, India

During 1981 kharif, 22 varieties were

grown in 20-hill rows. Two plantings

were done, one at the usual time and the

second 15 days later. Recommended

management practices were followed.

The number of whorl maggot-

damaged leaves was recorded on

10 hills/ variety at 30 and 45 days after

transplanting (see table). Ptb 12 and Ptb

21 had the least damage, Ptb 19 the

most damage.

Incidence of whorl maggot damage on rice

varieties at Aduthurai, India.

Whorl

Variety maggotincidence

(%)

ARC6632 10.1Banglei 8.5Chemban 9.3Chempan 11.6Chitteri 10.7Cheriya Chitteri 11.4Kula Peruvela 11.4

Leaung 152 11.7NagrasalPtb 12

12.9

Ptb 193.4

Ptb 2116.5

Ptb 335.5

13.0Parakulam 10.5SulaiT 10

12.98.8

Vellai Langayan 11.4Valsara Champara 14.3Vellathil cheera 11.7Lal Basumati 10.3TN1 (susceptible check) 11.1

L x H/2-281 12.4



10/20

Reaction of rice cultivars to gall

midge attack in Orissa

B. C. Jena, research scholar, and N. C. Pat-

naik, entomologist, Orissa University of

Agriculture and Technology, Bhubaneswar;

and N. Panda, senior research fellow, Ento-

mology Department, International RiceResearch Institute

Rice gall midge Orseolia oryzae is a

serious pest in the wet season, but activ-

ity is also observed in the dry season in

areas receiving perennial flow irrigation.

Varieties in the coastal tract appear to

differ in level of susceptibility from var-

ieties in the inland districts.

A trial in the 1980 and 1981 wet sea-

sons at three representative sites

Bhubaneswar (Pun district), Rampur

(Bolangir district), and Chakuli (Sam-

balpur district) studied cultivar reac-

tions to variable insect population pres-

sure. The trial had 6 donor cultivars, 5

resistant varieties, 8 promising cultivars,

and 3 susceptible checks grown in a

completely randomized block design

replicated 3 times with 100 hills/replica-

tion. Silvershoot infestation was meas-

ured at 55 days after transplanting.

Siam 29 and Eswarkora exhibited

higher levels of silvershoot incidence at

all three sites in both years (see table).

Infestation level in Leuang 152, Ptb 18,

and Ptb 21 was less than 1%. Resistant

Effect of nitrogen fertilizer levels and

spacing on rice gall midge and leaf-

folder damage

R. Saroja and N. Raju, Paddy Experiment

Station, Tirur 602025, Chingleput District,

Tamil Nadu, South India

The effect of four nitrogen levels andthree plant spacings on rice pest damage

was studied in a field trial at Tirur dur-

ing the samba season, July-August to

November-December 1979-80. The two-

factor experiment was laid out in a ran-

domized complete block design with

three replications.

planted in 9-m2 plots with 50 kg

P2O5/ha and 50 kg K2O/ha. The crop

Thirty-day-old seedlings of IR8 were


Reaction of rice cultivars to gall midge infestation at 3 locations in Orissa, India, 1980 and1981.

Av silvershoots (%) at 55 DT a

Cultivar Parents Bhubaneswar Rampur Chakuli(Puri) (Bolangir) (Sambalpu

DonorsEswarkora 1.10 3.34 2.89

Leuang 152 0.00 0.07 0.24Ptb 18 0.03 1.10 0.55Ptb 21 0.00 0.19 0.19

Siam 29 5.69 7.28 10.18W1263 1.10 1.08 0.60

Resistant varietiesKakatiya IR8/W1263 4.95 2.30 4.29Shakti Ptb 18/Ptb 21//IR8 1.21 3.24 1.99

Phalguna IR8/Siam 29 0.41 1.40 0.46Surekha IR8/Siam 29 0.38 1.40 1.04Samlei IR8/Leuang 152 0.16 0.26 0.07

Promising cultivarsORSJR-214 IRI/Leuang 152 0.36 0.96 0.71

OR127-3 RPW 6-13/Hema 0.00 0.06 0.00

ORl40-9-3 RPW 6-13/CR94-MR 1550 0.00 0.15 0.55

ORl32-3-1 Rajeswari/CR57 0.13 0.33 0.89

CR199-1 RPW 6

-1 3/Supriya 0.07 0.00 0.13

CR401-6 Vijaya/CR94-15 12-6 0.95 1.29 1.47

CR404-24 CR94-1512-6/Pusa 2-21 0.10 0.00 0.06

RP8-9 IR8/W1257 10.19 13.08 4.46

Susceptible checks

Jaya TN1/T141 13.40 23.26 22.32IET5656 RPW 6-13/Sona 16.76 12.78 16.42RP356-112-1-1 IR8/Siam 29//Ptb 18/Ptb 21 17.10 18.07 8.19

aMean of 3 replications. DT = days after transplanting.

variety Kakatiya had high infestation at tion among donors, resistant varieties,

all three sites. Shakti had high level of promising cultivars, and susceptible

infestation only at Rampur. RP8-9 had checks with respect to test sites was v

high infestation at all three sites. low. Fluctuations in silvershoot inci-

Infestation in susceptible varieties was dence were mostly ascribable to envir-

very high. Variability in level of infesta- onmental influences.

Effect of nitrogen fertilizer and spacing on gall midge and leaffolder damage at Tirur, India, 1979-8

samba.

Nitrogen

(kg/ha) 10 x 10cm

0 11.2

75 14.0150 15.2225 14.8

Av 13.8

CD for N levelCD for spacing

CD for interaction

20 x 20

cm

8.8

11.010.312.2

10.5

30 x 30 Avcm

7.9 9.310.8 11.910.5 12.010.7 12.0

10.0

2.372.05

4.12

10 x 10 20 x 20 30 x 30 Avcm cm cm

24.4 20.2 18.7 2148.3 29.1 23.3

48.0 30.8 24.847.4 37.6 31.9 39

42.0 29.4 24.7

11

received no insect protection. 75 DT.

Gall midge damage was measured as Damage by gall midges and leaf-

the number of silvershoots to total tillers folders was rather high and increased

on 50 hills/ plot at 60 days after trans- significantly when nitrogen was added

planting (DT). Leaffolder damage was the plot (see table). Damage also

measured as the number of leaves dam- increased significantly at closer

aged to total leaves on 25 hills/plot at spacings.

5.

33

34

6.

Gall midge silvershoots (%) Leaffolder-damaged leaves (%)


11/20

Seven species of nematodes have been

found in rice plants and soil in the

Mekong Delta: Dirylenchus angustus.

Aphelenchoides besseyi, Meloidogyne

graminicola, Hirschmanniella oryzae

spp, Criconemella sp., Tybenchorhyno-hus sp., Helicotylenchus sp.

Populations of H. oryzae were studie

from about 1,000 soil samples and rice

roots from 100 paddy fields. Sampling

was done from tillering in the 1981 rainy

season main crop to tillering in the 1982

second crop. Main crop varieties were

Tau-bun, Tauchen, Nang-quot, Chum-

ran, Gay-xe, Chet-cut, Lem-lun, Bang-

senx. Second crop varieties were IR36,

Rice is grown in the hilly areas of

Darjeeling district on bench terraces up

to 1,335 m altitude. Annual precipita-

tion ranges from 2,800 to 3,900 mm.

The annual maximum temperatures

range from 15 to 24 C and minimum

temperatures from 75 to 19 C

depending on the altitude. Only one

medium to late duration rice crop is

grown during the monsoon season.

Economically important insect pests of

hill rice are in the table.

P. K. Banerjee and P. B. Chatterjee, Rice

Research Station, Chinsurah 712 102, West

Bengal, India

Pests of hill rice in West Bengal,

India

Influence of planting time on gall

midge incidence at Aduthurai

P. Karuppuchamy, S. Uthamasamy, and G.

Chakkaravarthy, Tamil Nadu Rice Research

Institute, Aduthurai 612 101, Tamil Nadu,

India

Rice gall midge Orseolia oryzae inci-

dence was measured on CO 40 in the

samba season and on IR20 in the tha-

ladi season. Plot size was 50 m2 with 4

replications. The number of silvershoots

in total tillers was counted.

During the samba season, maximum

gall midge incidence was on the crop

planted 1 September 1981 followed by

crops planted on 16 September and 16

August (see figure). Incidence was less

on crops planted on 2 and 17 October.

During the thaladi season, maximum

incidence was on the crop planted 16

September.

The 50- to 70-day-old crop in the

samba season and the 30- to 60-day-old

crop in the thaladi season were more

prone to gall midge infestation.

Gall midge incidence during samba and thaladi

seasons in Tamil Nadu, India.

Insect pests of hill rice in West Bengal, India.

Insect Seasonal incidence

Stem borersWhite stem borer Jul-Oct, peak seasonScirpophaga innotata in September

Gold-fringed borerChilo auricilia (Dudgeon)

(Walker)

Rice bug

Leptocorisa acuta

(Thunberg)

Aug-Oct

Green leafhopper Nephotettix virescens

Nephotettix nigropictus Jul-Oct

(Distant)

(Stl.)

Big white leafhopperTettigella spectra Distant Oct-Nov

Leaffolder

Cnaphalocrocis medinalis Sep-Nov(Guenee)

Gall midge

Orseolia oryzae(Wood-Mason)

Swarming caterpillarSpodoptera mauritia

(Boisduval)

Aug-Oct

Jul-Aug

Economic importance

Damage varies from 30% to 80% oftillers.

Loss estimated at 25-35% of

panicles.

Minor.

Minor.

At altitudes from 650-1000 m

about 25-40% leaves damaged. Late

crop most damaged.

At altitudes below 1000 m, 25-30%silvershoots.

Humid areas near perennial springsat lower altitudes are more infestedseedling damage.


Other pests

Hirschmanniella oryzae and other

nematodes found in rice paddies of

the Mekong Delta, Vietnam

Dang-ngoc Kinh and Bui-yan Ngoc, Plant

Protection Department, University of Hau-

Giang, Vietnam



12/20

IR42, IR2823-399-5-6, IR9129-163-3-2-

2, IR9129-192-2-3-5, and IR2307-247-2-

2-3. Nematodes were found in all

samples.

Populations in 50-gram root samples

of local varieties ranged from 12 to 380 ing, 860 to 11,200.

at tillering, increasing to 50 to 7,000 at Populations in 100-ml soil samples

flowering, and to 300 to 7,500 at ripen- averaged 71 throughout the sampling

ing. In the second crop, populations at period, with a range of 5 to 450

transplanting were 204 to 9,000; at tiller- nematodes.


Drought resistance

Using check varieties to adjust visual

scores for nonuniform soil drying in

drought resistance field screening

Nopporn Supapoj, Chaluay Boonwite,

J. C. OToole, S. K. De Datta, and

B. R. Jackson, joint contribution of the Rice

Division, Dept. of Agriculture, Bangkok-9,

Thailand; The International Rice Research

Institute, Los Baos. Philippines; and Rocke-

feller Foundation/IRRI Cooperative Pro-

jects with the Ministry of Agriculture and

Cooperatives, G. P.O. Box 24.53, Bangkok,

Thailand.

In many areas of monsoon Asia, the dry

season allows use of irrigation (surface

or sprinkler) to control timing (growth

stage) and duration of water stress in

drought resistance screening of germ-

plasm in the field. But variability in soil

drying results in problems in interpreting

visual scores among entries. Using soilmoisture measurements (tensiometers,

gypsum blocks, or gravimetric sampling)

to indicate relative soil water deficits

within a field has inherent technical

problems and is not generally

satisfactory.

A method using frequently spaced

check varieties to adjust or normalize

field screening results for heterogeneity

of soil drying has been developed.

Field screening for drought resistance

was conducted in the 1980 dry season at

the Klong Luang Rice Experiment Sta-tion, Thailand. Localized deviations of

IR20 (susceptible check) and BKN6986-

108-3 (local resistant check) from their

overall means were used to adjust scores

of entries in nearby plots. The figure

illustrates the heterogeneity of soil dry-

ing across the field that was identified by

the response of check varieties and devia-

tions from their respective overall

means.


Variation in soil drying

across field is illustrated

by changes in responses

of IR20 (susceptible

check) and BKN6986-

108-3 (resistant check).

IRRI.

Statistical analysis of original (A) and adjusted (B) visual drought resistance scores of 77 entries in

1980 dry season field screening for drought resistance at Klong Luang Rice Experiment Station,

Thailand.

CV (%) F-valueDMRT (5%)

discrimination

range (no.)

A 0.5603 29.9 2.12** A-G (7)B 1.0377 24.0 3.08** A-M (1 3)

At any place in the field, the average uniform soil physical properties or by

of the check varieties deviations from inequity of irrigation water

their respective means was applied to the distribution.

scores of adjacent entries, normalizing-

varietal response for soil moisture hete-

rogeneity. The ratio of varietal variance

) to expenmental variance was

used in evaluating the capabilif he Adverse soilsadjusted data to better differentiate

entries. Adjusting the original visual tolerancedrought resistance scores for field soil

GENETIC EVALUATION AND UTI LlZATION

moisture conditions increased the

ratio, decreased the CV, and

increased the capability of Duncans

Varietal tolerance for acid sulfate

soils in North Vietnam

Multiple Range Test (5% level) to differ- Dao The Tuan, plant physiologist, andentiate between entries (see table).

which are usually well known by the Vietnam

individual scorer to systematically cope

with the problem of inherent variability Varieties were screened for acid sulfate

in drought screening caused by non- soil tolerance during the 1977, 1978, and

This method uses check varietiesNguyen Huu Nghia, geneticist, Vietnam

Agricultural Science Institute, Hanoi,

s V2

sE2

(s V2 (sE2)

sV2/sE2


13/20

1979 dry seasons at Haiphong, 100 km

east of Hanoi. Soils had pH 3.1-3.4 with

4.45-6.20 meq exchangeable aluminum

The 245 varieties and lines screened

were selected from among local germ-

plasm and 1RRl lines tolerant of salin-

ity, drought, iron (Fe) toxicity, and

phosphorus (P) deficiency. Iron toxicity

was evaluated on the Standard Evalua-

tion System for Rice scale 4 and 8 weeks

after transplanting.

Most tolerant of acid sulfate soils

were local varieties Bu, Pokkali, Cut,

Cuom, and Chim da. (Table 1). Most

tolerant lines were IR2151-96-1-5-3,

IR2 153-26-3-5-6, IR1529-680-3-2, and

(Al)/ 100 g.

B9C-Md-3-3.

Tolerance for Al and Fe toxicity and

P deficiency was tested among 15 varie-

ties and lines at Thanh t experiment

station. Al toxicity was determined by

soaking germinated seeds in 3 and

30 mg Al/ liter soil solution. Fe toxicity

and P deficiency tests were done in pots.

Local variety Ba was tolerant of all

three factors (Table 2). IR2151-96-1-5-2,

which was less tolerant in the field at 8

weeks, also was less tolerant of iron.

A close relationship was found

between Al toxicity and P deficiency

(correlation coefficient 0.747). Toleran-

ces for Al and Fe toxicity were notrelated (correlation coefficient 0.299).

One month after transplanting, with

soil pH 4.0 and Al in the soil solution at

7.8 mg/ liter, field evaluation scores

correlated with AI toxicity tolerance (r=

0.917). But 2 months after transplanting,

with soil pH 4.9. field evaluation scores

did not correlate with Fe toxicity toler-

ance (r = 0.376), probably because both

factors had some influence.

IR lines with IR1416-131-5, CR94-13,

and Indonesian variety Sigadis in their

parentage are tolerant of Fe toxicity. In

these studies, tolerance of Al toxicity

and P deficiency seemed to be related to

the presence of Sigadis genes. It appears

that acid soil tolerance is related to tol-

erance for Al toxicity, Fe toxicity, and

P deficiency.

Three varieties IR2 I5 1-96 1-5-3,

IR2153-26-3-56. and B9C-Md-3-3

were selected for yield trials in North

Vietnam. IR2 153 also can be cultivated

Table 1. Field scoresa of representative varieties and lines in varietal screening on acid sulfate soilsb

in North Vietnam.

Variety or line Score Variety or line Score

CSSR-1IR2058-78-1-3-2-3 (IR46)IR2061-464-24-46

IET5 2 3 3

BG94-1

IR1529-430-2IR2053-160-1-2-2IR2070-719-3-5IR2153-26-3-5-2IR2053-436-1-2KI49PokkaliM1-48IR28

IR2153-43-2-5-3

IR2071-586-5-6-34IR2153-26-3-5-6

IR2823-399-56IR4573-4-3-7-14IR4595-4-1-13IR4630-22-2-17

IR4763-73-1-11

IR1514A-E666IR2031-2384-1-3-2IR26IR2061-214-2-24-1IR1529-680-3-2IR994-102-2-3-2-2-2IR2151-190-3-5-5lR2151-96-1-5-3

5

558

67

563

74-52

894

52

6

668

75-63-46

62-3552

IR40 4IR42 5

312151-598-3-5-5 4IR2863-38-1 3-4

IR4227-

164-

1-

1 6lR4613-54-5 9B9C-Md-3-3 2-3IR1529-430-3 3IR1750-F5B-5 4-5IR2035-117-3 5IR2035-242-1 5

IR2061-522-6-9 7IR3839-1 4-5

IR3880-13 8

IR3880-17 4

IR9575 3IRATl3 3

C22 3C46-151IR242 4lR36 5-6A4 3

IR8 7386 (NN75-7) 7Bu 1cut 2Cuom 2424 (NN75-2) 5

Sai duong 4-5Chiem da 2B541-bkn-19-34 3

a 1980 Standard Evaluation System for Rice scale of 1-9: 1 = growth and tillering nearly normal, 9 =

almost all plants dead or dying. bMean of 3 dry seasons.

Table 2. Tolerancea for acid sulfate soils and other stresses of different varieties and lines in green-house tests in North Vietnam.

Variety or lineAcid sulfate soils tolerane a Al toxicity P deficiency Fe toxici

1 mo 2 mo tolerance tolerance tolerance

Bu 1 1 1 1 1-2

IR2151-96-1-5-2 1 2 1 1 3-4

IR2153-26-3-5-6 2 3 3 3 4A4 2 3 3 3 2-4B9C-Md-3-3 3 3 3 3 4

424 (NN75-2) 1 5 1 1 5

B541-bkn52-3-3 5 3 5 3 4-5

IR42 5 6 3 3 53-5

IR46 5 7 3 3 5

IR9575 7 5 5 3 3

IR1529-680-3-2 5 4 5 5

386 (NN75-7) 5 7 5 1 3

IR4683-54

-3-3-2 5 3 7

IR2797-105-2-2-3 5 3 7IR8 7 5 7 5 5

a 1980 Standard Evaluation System for Rice scale of 1-9: 1 = growth and tillering nearly normal; 5 =growth and tillering retarded, many leaves discolored; 9 = almost all plants dead or dying.

in saline soils. IR2 I5 I, with tolerance for

P deficiency and resistance to brown

planthopper biotype 1, also is accepted

in regions where IR8 cannot be

cultivated.

Individuals organiozations and media

who wish additional details of.

information presented in IRRN should

write directly to the authors.



14/20

Pest management and control DISEASES

Relative humidity and nematode

number and survival in rice seeds

Nguyen-ti Thu Cuc and Le-Thanh Giang,

Plant Protection Department, University of

Cantho, Hau Giang, Vietnam

Seeds of rice varieties infested with

nematode D. angustus were collected in

Dong Thanp and Hau-Giang Province

(the Mekong Delta) and soaked in dis-

tilled water for 2 hours. Then, the husk

was separated from the albumen andseeds were resoaked for 1 hour.

Nematodes were found inside filled

and unfilled grains, between the tegmen

and albumen. They also can cling out-

side the tegmen.

Nematode populations in the seeds

varied with variety of rice. Two-day-old

seeds of local varieties Nep mua and

Lua Tieu with 16.5-17% relative humid-

ity were examined. In Lua Tieu, nema-

tode counts were 7 nematodes/ 100unfilled grains and 25/ 100 filled grains.

In Nep mua, nematode count was highe

63 nematodes/ 100 unfilled grains and

167/100 filled grains.

When infested seeds were dried in th

sun (44-45 C) for 4 days (6 hours/ day)

seed humidity decreased to below 12%

and nematodes were killed.

Fungicidal control of rice grain tine were tested for control of grain Fungicidal control of grain discoloration at

discoloration discoloration. Kannagi was the test Mettupalayam, India.variety. Application Discolor

Panicles at the milk stage were Fungicide rate graina

V. S. Duraisamy, agricultural officer, Train-

ing and Visit Programme, Mattupalayam sprayed with spore suspensions ofH.(%) (%)

641 301, India oryzae, T. padwickii, and C. lunata. Carbendazim 0.2 4.10.2 3.2

Yellow or brown discoloration of grain the fungicides. Percentage discolorationMancozeb 0.2 0.3

34% mancozeb 0.2 0.2

After 24 hours, they were sprayed with Baycar

is caused by fungi Helminthosporium was calculated at panicle maturity. IBP 0.2 0.3

oryzae, Trichoconis padwickii, and Cur- Application of 0.2% quazatine, IBP,Edifenphos 0.2 2.8

vularia lunata. Seven fungicides car- and mancozeb prevented discolorationQuazatine 0.2 0.2

Control 8.7

bendazim, Baycar, mancozeb, 34% in the field (see table). Baycar and car- CD (0.05) = 0.097

mancozeb, IBP, edifenphos, and quaza- bendazim were not effective. aMean of 3 replications.

Epidemiology of brown spot disease

of rice in Karnataka, India

S. Sannegowda and K. T. Pandurange-

gowda, Plant Pathology Department, Uni-

versity of Agricultural Sciences, Regional

Research Station, V. C. Farm, Mandya,

Karnataka, India

The development and spread of brown

spot disease were studied in the field and

the relationship between disease inci-

dence and weather factors wasexamined.

Binnybhog was sown monthly, from 1

January to 31 December 1980 at Man-

dya. Periodic observations of disease

development were made and daily max-

imum and minimum temperatures, rela-

tive humidity at 0730 hours and 1430

hours, rainfall, and sunshine were aver-

aged for each month.

Highly susceptible rice variety


Incidence of brown spot was 2.5% factors. October to December had max

from January to September, then sud- imum temperatures of 27-29 C and mi

denly increased to 45% during October, imum temperatures of 15-20 C, relativ

peaked at 50% in November, and humidity of 86-90 at 0730 hours and 58

dropped gradually to 40% in December 62 at 1430 hours, 0.2-2.6 mm rainfall,

(see table). The variability in disease and average daily sunshine of 7-9

incidence might be attributed to weather hours.

Weather factors and brown spot disease incidence at Mandya, Karnataka, India.

Brown spot Weather factors (av)

Month incidence Temperature (C) Relative humidity Rainfall Sunshine/d

(%)Max Min 0730 h 1430 h (mm) (h)

Jan 2 30 14 81 47 0 10Feb 3 31 19 85 41 0 12Mar 3 32 20 82 44 0 12

Apr 3 34 22 82 43 0 10

May 1 32 22 81 51 2.5 10

June 3 31 21 89 60 2.9 10Jul 5 29 20 86 62 2.7 8

Aug 5 28 20 89 66 4.4 6

Sep 5 28 20 91 65 11.0 8

Oct 45 29 20 90 60 2.6 7

Nov 50 2820 87 62 1.2 9Dec 40 27 15 86 58 0.2 8


15/20

Root-knot disease of rice in the

Mekong Delta, Vietnam

Dang-ngoc Kinh, N. M. Huong, and N. V.Ut, Plant Protection Department, Universityof Cantho, Hau-Giang, Vietnam

Local and improved rice varieties have been found infested with root-knot

nematodes in the Mekong Delta. The

summer and winter crops using

improved varieties were more seriously

attacked than the main crop. Despite

galls in the root systems, the main crop

was seldom damaged, because it had

standing water in the field. Floating rice

varieties such as Nang-Tay also were

infested. The nematode on Nang-Tay

was identified by C. Germani as

Meloidogyne graminicola.

yield of rice variety TN 73-2 and

methods of control were done in thefield in Kien-Giang Province. At 30 days

after sowing, gall numbers averaged 13-

15/plant. The nematode decreased plant

height by about 3 148% and rice yield

by about 65%.

tion of carbofuran and diazinon in irri-

Two studies of damage to height and

Either continuous flooding or applica-

gation water was highly effective con-

trol, increasing yield 100-160% over that

in the untreated plots and 70-90% over

that in the nondiseased plots. Both

chemicals gave good control at 10 and

20 kg commercial product/ha to 20 days

after treatment. Then, gall numbers

began to increase but did not causedamage. Continuous flooding gave

slower results, but the longer the flood-

ing, the fewer the number of galls.

Flooding the field with tidewater was

not effective. Neither control method

had much effect at booting.

Field soil as a source of rice stem

nematodes

Nguyen-thi Thu Cuc, Plant ProtectionDepartment, University of Cantho, Hau-Giang, Vietnam

The Baermann-funnel extraction

method was used to determine the pres-

ence of rice stem nematode Ditylenchus

angustus in submerged field soil in the

infested rice-producing region of An-

Giang and Hau-Giang Provinces.Infested soil contained 8-12 living nema-

todes in 90 ml of soil at the 0-20 cm

depth and 3-7 nematodes at 204 cm

depth.

D. angustus was not observed in soil

samples dried for 1.5 months. Dried

infested soil was used to grow rice plants

in the greenhouse. Disease symptoms

were recorded 2 months after transplant-ing. Infected seedlings were 14.2% to

18.1% in dry soil from the 0-20 cm

depth and 12.1% to 14.4% in dry soil

from the 20-40 cm depth.

Pest management and control INSECTS

Parasites of the rice slug caterpillar

P. B. Chatterjee, entomologist, All IndiaCoordinated Rice Improvement Project,

Chinsurah R. S. 712102, West Bengal, India

A slug caterpillar, Latoia (Parasa) bico-

lor Walker (Lepidoptera: Limacodidae),

regularly appears on rice in Coochbehar,

Jalpaiguri, and in the plains of Darjeel-

ing near the foothills of the sub-

Himalayan ranges. The spined caterpil-

lars cause extensive foliar damage from

July to October, often necessitating

retransplanting. Grubs cause severedermal itching and urticaria on touch.

The arthropod enemies of L. bicolor

are two hymenopterous parasitoids:

Brachymeria euploeae Westwood (Chal-

cidoidea: Chalcididae) and Goryphus

busilaris Holmgren [Ichneumonoidea:

Ichneumonidae]. They parasitize 24%

of the pest's pupae in the field. In gen-

eral, third and fourth generations ofL.

bicolor are more parasitized.

Sepedon sphegeus (Fabr.)

(Sciomyzidae) and Notiphila spp.

(Ephydridae ): alternate hosts of

Trichogramma japonicum Ashmead,

a rice stem borer egg parasite

Alberto T. Barrion, research assistant, and

James A. Litsinger, entomologist, Entomol-

ogy Department, International Rice

Research Institute

In the Philippines, Trichogramma

japonicum Ashmead is a common egg

parasite of rice stem borers Scirpophaga

incertulas, Chilo suppressalis, and C.

polychrysus. Eggs of two genera of

flies that inhabit rice fields Sepedon

sphegeus (Fabr.) (Sciomyzidae) and

Notiphila latigenis Hendel, N. similis

Meijere and N. spinosa Cresson (Ephy-

dridae) were collected in the field in

Incidence of parasitization by Trichogramma japonicum on eggs of Sepedon sphegeus andNotiphilaspp. collected from 6 fields in the Philippines, 1981-82.

Sepedon sphegeus Notiphila spp.a

held zation held zationProvince Municipality Sampling date Eggs Parasiti- Eggs Parasiti

(no.) (%) (no.) (%)

CagayanLaguna

Agusan del SurBukidnon

North CotabatoZamboanga del Sur

SolanaLos Baos

Del MonteKalilanganKabacanPagadian

23 Sep 1981

7-17 Dec 198118-29 Jan 19828-24 Feb 1982

26 Jul 198129 Jul l9814-6 Jan 19823-4 Aug 1981

23-27 Nov 19816

11

518240

006

036.4

20.0

5.58.3

0

1452

181162234

24

362218

14.3

8.02.07.4

10.306.05.0

a Notiphila latigenisHendel, N. similis Meijere, and N. spinosa Cresson.



16/20

1981-82 in six provinces. T. japonicum encounter both. Even though fly eggs two fly genera would maintain Tricho-occurred in at least one fly species (see are much larger than stem borer eggs, gramma in the field at times of low stemtable). they are acceptable to the wasps. borer populations, enhancing its effec-

Sepedon and Notiphila lay egg masses Low rates of parasitization in fly eggs tiveness as a natural enemy of stem

on rice leaves in a similar manner as the indicate that stem borer eggs are pre- borers.

rice stem borer. Trichogramma wasps ferred. But such alternate hosts as these

Populations of gall midge, white-

backed planthopper, and thrips on

Pragati paddy

S. K. Shrivastava, C. L. Patidar, B. C.

Shukla, D. J. Pophaly, U. K. Kaushik, P. D.

Deshmukh, and G. A. Gangrade, Zonal

Agricultural Research Station (ZARS),

Agriculture College, Raipur, Madhya Pra-

desh, India

Pragati paddy was transplanted on 25

August 1979 at the ZARS Labhandi

Farm, Raipur. Three sets of 50 hillseach were monitored at intervals of 1, 4,

and 7 days beginning 1 day after trans-

planting (DT), for gall midge, white-

backed planthopper, and thrips infesta-

tion. Another 100 hills were treated with

malathion 50 EC 0.05% on 9 and 24

September, 16 October, and 3

November 1979, and monitored.

In untreated hills, gall midge infesta-

tion started on 10 September (16 DT).

Beginning 17 September, there was a

sudden increase in silvershoot develop-

ment, peaking 25 September (30 DT). In

treated hills, silvershoot development

also peaked 25 September, then declined

(see figure).

Whitebacked planthopper popula-

tions on untreated hills began to in-

crease on 11 September (17 DT), peaked

on 10 October (45 DT), then declined

sharply. In treated hills, the increase was

the same as in untreated plants, but

populations declined temporarily after

each spraying, then increased again but

did not attain the level of untreated hills.

By 14 November, populations were very

low.

Thrip populations were heavy up to

10 September (16 DT) on untreated

plants, then declined to near zero on 10

October (45 DT). After 31 October (62

DT), populations again increased

rapidly, peaking on 7 November (69

DT). In treated plants, populations were

negligible.


Populations of silvershoots,whitebacked planthoppers (WBPH),and thrips on transplanted Pragati

paddy, with or without malathion50 EC 0.05%. Madhya Pradesh,India.


17/20

Table 2. Population buildup of whitebacked planthopper on N22 rice variety grown with differentlevels of SiO2 at IRRI.

a

SiO2 (ppm) Leaves Mortality25 DAI

in culturesolution 5 DAI (no.) (no.) (no.)

(no.)(%) Nymphs Males Females

Total

0 1.2 a50 4.2 b

100 4.4 b150 4.4 b

16.0 a36.0 a

24.0 a28.0 a

188.2 a100.6 ab

91.8 b

61.4 b

35.6 c42.4 bc

52.6 ab

53.8 a

25.4 a21.8 b

17.4 c

18.2 c

249.2 a

164.8 ab

167.8 abc133.4 bc

aAv of 5 replications. Separation of means in a column under each level by Duncans multiple range

test at the 5% level. DAI = days after infestation.

Survival of whitebacked planthopper

(WBPH) nymphs on rice seedlings

growing in culture solution with three

silica (SiO2) levels was examined.

from 5.5 to 6.0. Each silica level was

replicated five times.

When plants were 15 and 30 days old,

10 first-instar nymphs were introduced

in each cage.

On plants treated with silica, very few

nymphs developed into adults (Table 1).At 15 days after infestation, the highest

number of adults was recorded on

plants with no silica.

For population buildup counts, 5

pairs of 3- to 5-day-old WBPH adults

were introduced in each cage. Surviving

adults were counted 5 days after caging.

Progeny were counted when plants were

35 days old.

The number of nymphs was highest at

0 ppm SiO2 and lowest at 150 ppm

(Table 2). The number of malesincreased as silica concentration

increased.

Apparently SiO2 induces development

of males but inhibits feeding of

WBPH.

Effects of silica level on whitebacked

planthopper

Hong-Sun Kim, research scholar, and

E, A. Heinrichs, entomologist and depart-

ment head, Entomology Department, Inter-

national Rice Research Institute

Table 1. Effect of silica on survival of whitebacked planthoppersa at IRRI.

SiO2 (ppm)in culture

Av no.

leaves/plantsolution

Surviving whitebacked planthoppers b (no.)

10 DAI 15 DAI 20 DAI 25 DAI

N A N A N A N A

0 6.8 a 8.6 a 1.4 a 5.4 a 4.2 a 0.0 b 9.2 a 0.0 a 9.2 a 53.0 a

50 5.2 b 8.0 a 0.2 b 5.4 a 2.2 b 0.0 b 7.0 b 0.0 a 7.0 b 0.0 b

100 4.2 b 6.6 b 0.0 b 5.0 a 1.8 b 0.4 ab 5.8 c 0.0 a 6.2 b 0.0 b150 4.2 b 6.4 b 0.0 b 4.6 a 1.2 b 0.8 a 5.0 c 0.0 a 5.8 b 0.0 b

a Av of 5 replications. Separation of means in a column and under each level by Duncans multiple range test at the 5% level. bDAI = days after infestation

N = nymphs, A = adults, NG = new generation.

One 10-day-old seedling of variety

N22 (Wbph 1 gene for resistance to

WBPH) was transplanted to each pot

containing a culture solution. Each pot

was put in a cage. A 60-liter culture

solution contained 100 ml N, 100 ml P,

100 ml K, 100 ml Ca, 100 ml Mg, 10 ml

microelements, 60 ml Fe EDTA.

Graded levels of silica as sodium meta-

silicate (Na2SiO35H2) were added to the

culture solution and the pH adjusted

Disruption of striped rice borer

males orientation to pheromone

traps

J. O. Lee, H. G. Goh, Y. H. Kim, and

J. S. Park, entomologists, Institute of Agri-

cultural Sciences, ORD; and J. H. Kim and

C. H. Park, scientists, KAIST, Korea

Disruption of male striped rice borer

(Chilo suppressalis) orientation to moni-

toring traps by a single spray application

of pheromone was investigated in paddy

fields in 1981. Microencapsulated

pheromone formulation as a mixture of

(z)-11-hexadecenal and (z)-13-

octadecenal at 4.5:1 was prepared by

urea (1) formalin (2) copolymerization,

mixed with a spreader, and sprayed at

10 mg and 30 mg on weeds of paddy

Disruption by microencapsulated pheromone of male striped borer moth orientation to monitoringhap. a Korea, 1981.

Time after pheromoneMales trapped (no.)

application 10 mg 30 mgb

(days) Treated Not Treated Nottreated

Treated Not

Before treatment

12

34

5

6

789

10

11121314

Total trapped

50

0

101

0

0

1110000

5

194

1

100

1

0

0110102

12

9 11 23 190 2 0 60 1 0 8

0 2 0 60 1 0 100 1 0 70 1 0 2

0 1 0 3

0 2 0 10 2 0 20 0 1 43 4 1 02 2 0 13 3 3 3

10 25 5 57

2 3 0 4

aTrap baited with 100 g pheromone as the attractant source. b30 mg applications in two differentareas.


treated treated


18/20

bank around a monitoring trap contain- from 10 days before application to 15 30 mg for 7-10 days (see table). Theing 100 g attractant. days after. The ability of male moths to pheromone had lost much of its disrup

Males caught were counted daily locate the trap source was suppressed at

Soil and crop management

Nitrogen management in flooded

rice

B. Mishra and R. D. Sharma, Soil Science

Department, G. B. Pant University of Agri-

culture and Technology, Pantnagar 263145

India

A field experiment on flooded rice in the

1981 monsoon season evaluated urea

briquet placement (5 cm below soil sur-

face), margosa seedcake-coated urea,

shellac-coated urea, sulfur-coated urea,

farmyard manure (FYM) + urea, and

urea split application. Experimental field

soil was silty clay loam (Mollisol). Each

nitrogen source was applied at 60 kg

N/ha.

There was no yield advantage in 3

split applications of urea over 2 splits at

60 kg N/ha (see table). Margosa

seedcake-coated urea and shellac-coated

urea also did not offer any significant

improvement in yield over urea appliedin three split doses. Urea + FYM was

equal to urea alone (3 splits).

Sulfur-coated urea produced signifi-

cantly higher yields than did ordinary

urea applied in three split doses. Urea

briquet placement 1 week after trans-

Algae in rice fields of Chingleput

District, Tamil Nadu, India

J. Venkatakrishnan and K. Narayanan,

Paddy Experiment Station, Tirur - 602 025,

Tamil Nadu, India

Samples of algae were collected during

October and November 1981 (monsoon

season). Rainfall during the period was

370.9 mm, maximum temperature range

was 39.0-25.5 C, and minimum

temperature range was 24.5-16.5 C.

Standing water of 1-2 cm was main-

tained in the fields by lift irrigation from

an open well.


Yield of rough rice at 60 kg N/ha.a

Nitrogen source Method and time of applicationGrain yield

N useefficiency(t/ha)

(kg grain/kg N

NoneUrea Broadcast, 3 splitsUrea Broadcast, 2 splits (transplanting and

Urea

Urea briquet Placement at 5 cm, 1 wk after trans-

Urea briquet Placement at 5 cm, 3 wk after trans-

Margosa seedcake- Broadcast at transplanting

Margosa seedcake- Broadcast 2 splits (transplanting and

Shellac-coated urea Broadcast at transplantingSulfur-coated urea Broadcast at transplantingFYM + urea

(30 + 30)Broadcast and mixed in soil before

FYM + ureatransplanting

FYM mixed with soil before transplanting(30 + 30) and urea broadcast 3 wk after trans-

tiller initiation)

panicle initiation)Broadcast, 2 splits (tiller initiation and

planting

planting

coated urea

coated urea tiller initiation)

planting

S.Em C.D. 5%

aFYM = farmyard manure.

3.323.98 114.21 15

4.24 15

4.85 25

5.37 34

3.98 11

3.81 8

4.24 154.43 183.64 5

3.99 11

0.15 0.45

planting was also significantly superior The highest yield was with urea brique

to ordinary urea (2 or 3 splits), but gave placement 3 weeks after transplanting

lower yields than placement 3 weeks Nitrogen use efficiency with urea bri

after transplanting probably because quet was more than 2 times as high as

of the relatively long growth period (144 2 or 3 split applications of ordinary

days) of the rice variety (Jaya) grown. urea.

Abundance of nitrogen-fixiing algae (Cyanophyta Effect of seedling age on susceptibspecies). Tamil Nadu, India.

Species

ity to aluminum toxicityRelative

abundancea

Gloeocapsa decorticans x Mai Van Quyen and S. Yoshida, Interna-

Anabaena oryzae xx tional Rice Research InstituteCylindrospermum muscicola x

Nostoc sphaericum x Aulosira prolifica x Although aluminum toxicity is rarely a

Calothrix sp. problem in wetland rice, it may impair

ax = rare, xx = moderate. growth even in flooded soils when soil

pH remains low because of strong acid-

Species of algae identified consisted of ity and low microbial activity. Relative

11 Cyanophyta, 6 Chlorophyta, 2 young seedlings may fail to establish on

Euglenophyta, and 5 Bacillariophyta. Of some acid sulfate soils.

the 11 Cyanophyta species, 6 are known Solution culture technique was used

to be nitrogen-fixing algae (see table). to examine the effect of seedling age on

tive effect 10 days after application.


19/20

susceptibility to aluminum toxicity. Two

varieties (IR26 and IR36), 3 plant ages

(10-, 20-, and 30-day-old seedlings), and

3 aluminum concentrations (0, 30, and

60 ppm) were used. At a specified plant

age, seedlings were transferred to a plas-

tic tray containing culture solution and

different levels of aluminum. They were

grown for 14 days in a glasshouse room

maintained at 29/21 C (day/night)

with natural light and 70% relative

humidity.

IR26 and IR36 showed a similar

trend. A larger difference was found in

shoot weight than in root weight (see

table). Stunted growth in 10-day-old

seedlings was noticed at 60 ppm Al.

Comparison of zinc sulfate and

Zn-EDTA as foliar spray

P. C. Srivastava, R. S. Sachan, and

M. S. Gangwar, Soil Science Department,

G. B. Pant University of Agriculture and

TechnoIogy, Pantnagar-263145, India

Chelated formulations of zinc (particu-

larly Zn-EDTA) have been recom-

mended as foliar spray. The absorption

efficiencies of Zn-EDTA and conven-

tional ZnSO4 + lime spray were com-

pared in a pot experiment.

A silty clay loam soil containing

1.30 ppm DTPA extractable Zn was

used at 2 kg/pot. Two 20-day-old Jaya

seedlings in each of 20 pots were

sprayed with one of 5 Zn treatments 15

days after transplanting. Treatments,

replicated 4 times, were: control (no Zn);

100 ppm Zn as 0.044% ZnSO4 + 0.022%

lime spray; 100 ppm Zn as chelated Zn

(manufacturers recommended rate);

1,130 ppm Zn as 0.5 ZnSO4 + 0.25%

lime (recommended spray), and

1,130 ppm Zn as chelated zinc(Sukshmin-Z).

Both ZnSO4 and chelated Zn foliar

spray increased dry matter and Zn

uptake over the control (Fig. 1). Yield

with 100 ppm chelated Zn was 37%

higher than the control. Dry matter

yield and Zn uptake did not differ signifi-

cantly with 100 ppm and 1,130 ppm Zn

as ZnSO4, nor with 100 ppm and 1,130

ppm chelated Zn.

Effect of seedling age and aluminum concentration on average root and shoot weights of 2 rice varie

ties grown in culture solution at IRRI.a

Seedling age Al addedRoot weight Shoot weight

(days) (ppm) mg/plant % of check mg/plant % of chec

10 0 83 100 266 100

30 69 83 171 64

60 62 74 132 49

20 0 298 100 908 10030 272 91 878 96

60 238 79 830 91

30 0 677 100 2143 10030 544 80 2032 94

60 499 73 2159 100

a

Figures are mean values of IR26 and IR36.

These results indicate that, in soils old) seedlings is not advisable. Twenty-

where aluminum toxicity is a potential day-old or even older seedlings would

problem, planting dapog (about 11 days minimize risk of stand failure.

1. Effect of zinc foliarsprays on rice dry matteryield and zinc uptake.

2. Effect of zincfoliar sprays onrice uptake ofcopper, iron, andmanganese.



20/20

international rice research newsletter vol.7 no.4

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