International Rice Research Newsletter Vol.8 No.2

Guidelines and Style for

IRRN Contributors To improve communication and to speed the edi- tonal process the editors of the Internatinal Rice Research Newsletter (IRRN) request that contributors use the following style and guidelines:

Style • Use the metric system in all papers. Aviod

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

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

• Define in footnotes or legends any abbreviations or symbols used in a figure or table

• Place the name or denotation of compounds or chemicals near the unit of measure. For example 60 kg N ha; not 60 kg ha N.

• The US dollar is the standard monetary unit for the IRRN. Data in other currencies should be converted to US$.

• Abbreviate names of standard units of measure when they follow a number for example: 20 kg ha.

of measure spell out in full the first time of refer- ence, with abbreviations in parenthesis, then use the abbreviation throughout the remaining text. For example: The efficiency of nitrogen (N) use was tested. Three levels of N were . . . or Biotypes of the brown planthopper (BPH) differ within Asia. We studied the biotypes of BPH in . . .

• Express time, money, and measurement in numbers, even when the amount is less than 10.

7%; 4 hours. For example: 8 years; 3 kg ha at 2-week intervals;

• Write out numbers below 10 except in a series containing 10 or some numbers higher and some numbers lower than 10. For example six parts; seven tractors; four varieties. But There were 4 plots in India, 8 plots in Thailand, and 12 plots in Indonesia

• Write out all numbers that start sentences For example: Sixty insects were added to each cage; Seventy-five percent of the yield increase is attributed to fertilizer use.

Guidelines • Contributions to the IRRN should generally

be based on results of research on rice or on crop- ping patterns involving rice.

• Appropriate statistical analyses are required for most data.

• Contributions should not exceed two pages of double-spaced, typewritten text. Two figures (graphs, tables. photos) per contribution are per- mitted to supplement the text. The editor will return articles that exceed space limitations

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

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

ieties are encouraged.

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

• When using abbreviations other than for units

• Announcements of the release of new rice var-

• Use common — not trade — names for com- mercial chemicals and, when feasible equipment

contributions. • Pest surveys should have quantified data

• Do not include references in IRRN

(%infection, degree of seventy, etc.).

Genetic evaluation and utilization OVERALL PROGRESS

Fertility restorers for cytosterile stocks

P. L. Mohanty and N. P. Sarma, Central Rice Research Institute, Cuttack 753 006, Cuttack, India

The discovery of an effective cytoplasmic genetic male sterility system led to successful hybrid rice development in China. Identification of restorer genotypes to ensure fertility restoration in F 1 hybrids produced with cytogenetic male sterile (cms) stocks is important.

Standard varieties, cultures in advanced evaluation stages, and elite breed-

ing lines entered in the International Rice Observational Nursery, International Rice Yield Nurseries, and National Eval- uation Trials were screened to identify fertility restorers that could be used in F 1 hybrid production. Growth duration of genotypes used as pollinators was less than 135 days. The common female parent for pollinators was cms V.20A. Hybrids were produced by hand pollina- ting cms stock. F 1 hybrids were grown in a test cross nursery and evaluated for pollen fertility and percent seed set. Pol- len fertility was determined by cytologic-

Restorers and maintainers for WA cytosterile stocks identified at CRRI, Cuttack, India.

Effective restorers Partial or weak restorers Maintainers (nonrestorers)

Varieties PR106 Jaya PR107

Madhu Prakash

Mahsuri Karikalan

Akash MW 10 Archana Amarnath Kaveri Jamuna Parijatha N22

Gaur-I Kumar C-22 Kalinga II Ratna Rasi Triveni Kranthi

IET2815 IET6314 IET6983 IET6721

CRl29-118 BR40-178-2-1 BR171-213-8 BIET360 BKN7033-13-1-1-3-2 UPRl03-80-1-2-1-2 IR8455-78-1-3-3 IR8608-125-3-3 IR9129-457-2-2-1-2 IR9224-73-2-2-2-3 IR9698-16-3-3-2 IR9761-19-1 IR9784-142-1-3-3 IR13204-3-3-3-2 IR13429-109-2-2-1 IR13525-43-2-3-1-3-2 IR15529-256-1

Advanced cultures IET4141 IET6148

Elite breeding lines BR109-74-2-2-1 BR319-1 AD7486 RP825-28-7-1 RP975-26-4-7-1 RP1017-169-1-4 RP8205-45-1-3 R35-2750 B733C-167-3-2 MR136-1 KAU1924 TNAU17005 IR129-209-2-2-2-3 IR2071-586-5-6 IR3475-G2CO-CNT-84-1-1 IR9209-26-2-2-2-3 IR9710-98-2 IR13427-45-3-1-2 IR13540-56-3-2-1 IR15314-43-2-3-3 IR15496-219-2-3

Rasht 545 BW-242-5-5 ES3-17-164 KAU-1675 WGL-26420 IR129-209-2-2-2-3 IR9761-40-3-2 IR13240-39-3 IR13525-43-2-3-1-3-2 IR19743-46-2-3 IR19764-15-1-1 IR19819-31-2-3 IR21931-67

IRRN 8:2 (April 1983) 3

J. S. Nanda, S. C. Mani, Harpal Singh, J. P. Singh, and C. V. Singh, Plant Breed- ing Department, College of Agriculture, G. B. Pant University of Agriculture and Technology, Pantnagar 263145, U. P., India

Govind, an early-maturing variety developed from the cross IR20/IR24, was recently released in Uttar Pradesh for general cultivation. Govind is a semidwarf (90 cm) variety that can be direct-seeded in rainfed fields or transplanted. It has 95- to 109-day maturity when direct- seeded in rainfed fields and 105-110 days when transplanted. Grains are long, slender, and translucent with good cook- ing quality and intermediate amylose content (23%).

Govind has been tested throughout Uttar Pradesh and in All India Coordina- ted Rice Improvement Project (AICRIP) trials for 5 years. Its performance in the AICRIP uniform variety trials is given in Table 1. Performance in the upland direct- seeded standard varietal trials and station trials (transplanting) is given in Tables 2 and 3.

Govind resists bacterial leaf blight, leaf blast, and brown leaf spot diseases and is moderately resistant to planthop-

Very early-maturing rice varieties were evaluated for direct seeding as part of the All India Coordinated Rice Improvement

Project Uniform Variety Trial I. Seed was soaked for 12 h and broadcast in puddled, leveled soil at 110 kg/ha. Water was care- fully controlled for 1 week and then the crop was regularly irrigated. Trials were conducted in both kharif and rabi.

Cauvery and Tellahamsa, a popular short-duration high yielding variety, were checks. IET6148, 6149, 5860, 6155, 5858,4106,4107, and 6233 have been

evaluated since 1979 kharif. IET6148, a progeny of Bala/Co 13,

developed at Tamil Nadu Agricultural University, gave consistently high (5.8 t/ha) yields. During 1979 kharif IET6148 was superior to all entries and yielded 6.2 t/ha. In 1980 kharif and 1981 rabi it yielded 5.9 and 6.1 t/ha, equal with Tellahamsa. ET6148 flowers in 75 days and has short bold grain.

D. Jayaraj, Agricultural Research Insti- tute, Rajendranagar, Andhra Pradesh, India

al examination of pollen grains stained ration was above 80%: weak restorers or to produce F l hybrids for evaluating he- with I-KI solution. Percent seed set under integrades where fertility restoration was terosis and combining ability. A recurrent self-pollination was evaluated by bagging 20-80%; and maintainers (nonrestorers) backcross that uses maintainers to trans the main panicles of the hybrid plants. where fertility restoration was less than fer the genome into wild aborted (WA)

The pollinators were classified as: 10% (see table). cytoplasm for developing additional cms effective restorers, where fertility resto- The effective restorers are being used stocks is in progress.

GENETIC EVALUATION AND UTILIZATION

Agronomic characteristics IET6148, a variety for direct seeding

Govind, an early-maturing rice variety Table 1. Performance of Govind in AICRlP trials when direct-seeded in upland rainfed fields.

Grain yield (t/ha) Days to

(mean of (mean of (mean of Average (1980) Variety 1979 1980 1981 50% flowering

23 locations) 31 locations) 17 locations)

Govind 3.3 3.4 3.1 3.3 75 Bala 3.2 – Cauvery 2.9 2.8 2.3 2.7 74 Akashi 2.8 – 2.8 69 Local check 3.4 3.3 2.5 3.1 75

– 3.2 –

–

Table 2. Performance of Govind in standard varietal trials in U.P. when direct-seeded in upland rainfed field.

Variety Grain yield (t/ha)

1980 Days to

1981 Average maturity (1981) (mean of 7 locations) (mean of 6 locations)

Govind 2.1 2.5 2.3 96 Cauvery 2.1 a 2.0 2.1 98 N22 1.4 1.8 1.6 87

a 5 locations only.

Table 3. Performance of Govind in U.P. when transplanted in station trials.

Grain yield (t/ha)

1979 1980 (mean of 6 locations) (mean of 9 locations)

Days to Variety 50% flowering

Average (1980)

Govind 5.1 3.9 4.5 81 Saket 4 5.1 4.4 4.7 87

4 IRRN 8:2 (April 1983)

Sheath rot incidence in cultivars grown at different nitrogen levels

A. K. Misra and S. C. Mathur, Plant Pathology Division, Central Rice Research Institute (CRRI), Cuttack 753 006, Orisso, India

Incidence of sheath rot caused by Acro- cylindrium oryzae was recorded for 26 rice cultivars that received 50, 100, 150, and 200 kg N/ha at CRRI farm during 1981 kharif. Only Pankaj showed resistance at all nitrogen levels. Six cultivars were moderately resistant, 8 were moderately susceptible, and 11 were susceptible (see table).

In general, sheath rot susceptibility

pers and leaffolders. Tests conducted by the AICRIP plant physiology section show Govind can sustain drought for 9 days during the vegetative stage. It is a low tillering variety and should use closer spacing (20 cm × 10 cm) with 2-3 seedlings/hill when transplanted.

The International Rice Research Newsletter (IRRN) invites all scientists to contribute concise summaries of significant rice research for publication. Contributions should be limited to one or two pages and no more

meet space limitations. Authors will be identified by name, title, and research organization. than two short tables, figures, or photographs. Contributions are subject to editing and abridgement to

Ratoon rice can yield well Grain yield and days to maturity of rice grown as a main crop in wet and dry seasons and as a ratoon crop after the dry season crop. West Bengal, India, 1980-82.

R. L. Nayak, M. Das, and S. S. Mandal, Agronomy Department, Faculty of Agri- culture, Bidhan Chandra Krishi Viswavid- yalaya, Kalyani 741235, Nadia, West Bengal, India

Nine medium-duration rice cultivars were tested for ratoon growth and yield in a randomized block design with three replications during 1980-81 dry season in West Bengal, India. Four of the cultivars were also grown as a main crop during 1980 wet season.

The dry season crop was harvested in summer and allowed to grow as a ratoon crop during 1981-82 wet season. Nitrogen at 20 kg/ha was topdressed during early vegetative phase and pesticide was sprayed prior to flowering. No irrigation was used because 1,000 mm rainfall fell during crop growth.

Some cultivars showed good ratooning ability and matured about 14 days earlier

Main crop Ratoon crop

Grain yield Days to (t/ha) maturity

Cultivar Grain yield (t/ha) Days to maturity

Wet season Dry season Wet season Dry season

IET3273 3.4 3.9 115 130 1.8 101 IET3305 4.2 130 1.2 101 IET3306 3.4 130 0.5 101 IET3629 2.4 4.8 110 140 2.7 95 IET3630 3.1 3.9 114 130 1.5 101 IET4555 4.7 140 2.1 95 IET5857 3.3 3.1 118 130 0.4 101 Ratna 4.5 130 0.6 101 Local 3.8 130 0.7 101

CD (0.05) 0.46 0.27

than the main wet season crop and a less than main crop yield in dry season. month earlier than the main dry season It matured 15 days (wet season) and 45 crop. days (dry season) earlier than the main

the shortest time (95 days) (see table). Other cultivars with good ratooning Its ratoon yield was 12% higher than ability were IET4555 (2.1 t/ha) and main crop yield in wet season and 44% IET3273 (1.8 t/ha).

IET3629 yielded highest (2.7 t/ha) in crops.

GENETIC EVALUATION AND UTlLlZATION

Disease resistance Reaction to sheath rot of 26 rice cultivars grown at different nitrogen levels, CRRI, Cuttack, India, kharif 1981.

Disease score a at different nitrogen levels

50 kg/ha 100 kg/ha 150 kg/ha 200 kg/ha Cultivars

Resistant Pankaj 0 0 0 0

CR294-548-1, RTM68 Jagannath, IR28, IR36 IR8

CR318-549, PR106 CR316-639-1, IR4432-664-2

CR318-461

0 Moderately resistant

1 3 3 1 3 3 3 0 3 3 3

Moderately susceptible 1 3 3 5 1 3 5 5 1 5 5 5

IR2071-178-3, CR.316-639-2, IR4432-664-1 3 3 5 5

Susceptible CR318-548-7 1 3 3 7

CONTINUED ON NEXT PAGE

IRRN 8:2 (April 1983) 5

plot experiment with five replications under irrigation in February 1980. The cultivars were randomly allocated to the main plots. There was no artificial inoculation; the disease developed from natural inoculum. Fungicide treatment (spraying vs no spraying) was randomly allocated to the subplots to generate different disease levels. The fungicide benomyl (Benlate 50 WP) at 1 kg ai/ha was sprayed 6 times at 2-week intervals starting 46 days after planting. Control plots were sprayed with water. Disease severity was assessed four times and scored using the Standard Evaluation System for Rice.

Disease differences were highly significant between the resistant and susceptible cultivars, and between the sprayed and unsprayed plots of the susceptible Faya Theresa (see figure).

The rice was harvested in July 1980 then sun-dried, threshed, winnowed, and weighed (adjusted to 14% moisture content). Paddy yields per hectare and 1,000- paddy grain weight in the sprayed and unsprayed plants of the two cultivars are in the table. There was an 18% reduction in yield and an 11% reduction in 1,000- grain weight in Faya Theresa. Both reduc- tions were highly significant. Disease by

Rice blast incited by Pyricularia oryzae is the most prevalent rice disease in Tanzania, but no empirical data on the extent of losses from it are available.

An experiment was conducted at Morogoro, central-eastern Tanzania, to determine the extent of loss caused by blast. Two rice cultivars — Kihogo Red (resistant to blast) and Faya Theresa (susceptible) — were planted in a split-

Others first showed ragged leaf symptoms and later leaf twisting. Still others first had vein-swelling symptoms. In

severely affected plants panicles did not exsert. The plants became shorter and shorter and finally died.

increased with increased nitrogen from 50 to 200 kg/ ha.

October 1981, when most of the cultivars were in the boot or flowering stage, was unusually dry (total rainfall 22.7 mm), with a minimum temperature of 23.1°C, maximum temperature 41° C, 77% relative humidity, and 8.9 hours sunshine. The dry weather appears to have favored sheath rot.

Screening of rice varieties for resistance to ragged stunt disease

L. G. Zhou, K. Y. Tu, L. Tsao, and S. Y. Li, Plant Protection Institute, Guangdong Academy of Agricultural Sciences (GAAS), Guangdong, China

Seeds of 47 rice varieties collected from southern and central China (Guangdong, Guang Xi, Hu Nan, Hu Bei, Jiang Xi, and Fu Jian Provinces) were sown in seedboxes. At the 3- to 4-leaf stage, 34 viruliferous brown planthopper adults were released on each plant and allowed to feed for 3 days. Seedlings were transplanted to the paddy field.

All test varieties were susceptible, except IR36 with an infection rate of 12.5% (see table). Highly susceptible Guang Lu Ai 4, Bai Zhen Long, Zhen Long 13, and Hong 410 were severely stunted. Tall varieties had no significant stunting at the early stage, but were severely stunted at later stages.

Some varieties first showed leaf twisting and later ragged leaf symptoms.

A note on rice blast in Tanzania

J. M. Teri and F. H. Ali, Crop Science Department, University of Dar es Salaam, P. O. Box 643, Morogoro, Tanzania

6 IRRN 8:2 (April 1983)

TABLE CONTINUED

Disease score a at different nitrogen levels 50 kg/ha 100 kg/ha 150 kg/ha 200 kg/ha

1 3 7 7 1 5 7 3

7 5 5 7

5 5 7 7 5 7 7 0

7 7 7 7

1 3 5 7

Cultivars

CR294-28-1, CR294-548-2 CR294-548-3, CR315-621 ET4141 Jaya, Ramkrishna PR107 BG90-2 CR188-10 a 1 = resistant, 3 = moderately resistant, 5 = moderately susceptible, 7 = susceptible.

Varietal resistance to ragged stunt, Guangdong, China, 1980.

Variety Inoc- In- In-

ulated fected fection Inoc- In-

(no.) (no.) (%) (no.) (no.) (%) Variety ulated fected fection

In-

IR36 32 4 12.5 Gui Chao Ai 39 38 97.4 lR29 20 6 30.0 Bai Yi Wan 1 30 30 100 Yu Chi 231-8 30 15 Guang Yu 73

50.0 Guang Lu Ai4 25 28

25 100 21

76-116 75.0 Hong 408 35 35

29 22 100

75.9 PII 299

Guang Er 104 18 18 100 30 24

PII 292 80.0

27 23 Bai Zhen Long 34 34 100

85.2 IR206 1 12 12 100 78-804 18 16 88.9 IR26 75-89

34 29 26 89.7 Qiang Hong 35-2 22 22 100

34 100

Shan You 2 23 21 Quan Ye Bai 30 75013

91.3 24 22

30 100 91.7 22-3

PII 293 29

21 29 100

25 92.6 150 91228 29

25 25 100 27

7055 29 93.1 Hong 410 25 25 100

27 93.1 Zhan Long 13 29 29 100 Wu Dong 51 15 14 93.3 Yuan Feng Zao 28 28 100 Nong Ken 58 25 24 96.0 Zhu Bian Xuan 26 26 100 Si You 2 27 26 96.3 Cong Siu Qing 23 23 100 E-Wan 3 27 26 96.3 5450 30 30 100

PI1 298 29 20 20 100

28 96.6 Gan Nan Wan 30 30 100 Er Jiu Qing 30 29 96.7 15-5 30 30 100 Shan You 3 30 29 96.7 PII 291 29 29 100 PII 300 30 29 96.7 TN1 28 28 100 Xiang Ai Zao 31 30 96.8

73-151 28 27 96.4 5180

variety interaction was also highly significant for yield, but not for 1,000-grain weight.

The weather during the experiment was drier than usual. Moreover, much of Tanzania's rice is dryland on which blast is severe.


Insect resistance Varietal resistance to white leafhopper

P. Sekar and S. Chelliah, Tamil Nadu Agricultural University, Coimbatore 641003, India

White leafhopper (WLH) Cofana spectra (Distant) is a major rice pest in India. Nymphs and adults suck plant sap and cause stunting followed by drying.

Glasshouse-cultured insects were used to study varietal resistance to WLH. Cages 45 × 45 × 60 cm, with wooden frames, glass tops and doors, and wire mesh side walls were used. From 50 to 70 field- collected WLH adults of both sexes were released in each cage and confined for 2 to 3 days for oviposition on 45- to 50- day-old potted TN1 rice plants. Plants with eggs were then moved to separate cages. Nymphs were transferred to fresh TN1 plants when necessary. A continuous adult population was mantained.

Seeds of test accessions were soaked in water for 24 h. Seeds sprouted in dark- ness. Three days after soaking sprouted seed were sown in 50- × 40- × 10-cm wooden flats filled with 5-7 cm of soil. Each flat held nine test accessions and the susceptible check TN1. One week after

With this scale, 16 of 39 rice accessions screened were resistant to moderately resistant (see table).

Detailed studies of the resistant acces-

sions CO 2, CO 29, and ASD5 have shown that nonpreference for orientation and oviposition, and antibiosis are principal resistance components.

IRRN 8:2 (April 1983) 7

sowing seedlings were thinned to 20/row and wooden flats were placed in galvanized 62- × 47- × 1.5-cm iron trays filled with 10 cm water. Fifteen days after sowing, 3 WLH adults/seedling were released on the flat and covered with a 55- × 45- × 50-cm nylon mesh cage. Dead insects were re- placed with live ones.

Damage was rated by row when 90% of the TN1 plants were killed. The following rating scale was developed.

Progress of rice blast in Kihogo Red and Faya Theresa with and without fungicide spray in Tanzania.

Effect of blast on rice yields in Tanzania.

Paddy yield 1,000-paddy grain wt

(t/ha) (t/ha) (%) (g) (g) (%)

Kihogo Red 2.70 2.59 4.1 31.41 30.29 1.1 Faya Theresa 3.04 2.49 18.1** 27.37 24.28 11.3**

** = highly significant difference ( P = 0.01).

Cultivar Sprayed Unsprayed Reduction Sprayed Unsprayed Reduction

Resistance rating of rice accessions to C. spectra, Coimbatore, India.

Accession Damage rating

2.35 2.40 2.90 3.00

ASD12 3.00 3.20 3.30

IET5741 3.40 3.40

ASD10 3.47 3.50

ASD14 3.50 CO 25 3.66

3.66 IET6315 3.80 CO 22 3.85

ASD2

Grade Criterion Rating

0 No visible damage Immune/tolerant 1 First leaf tip yellowing Highly resistant 3 First leaf drying and second Resistant

leaf tip yellowing, followed by drying

pronounced stunting or both

more than 50% of the plants

5

7

9

Yellowing of all leaves or Moderately resistant

Wilting, followed by drying of Susceptible

All plants dead Highly susceptible

Vazhaipoo Samba

ADT14 ASD3

ASD13 CH2 ASD5 CO 29 CO 2

Varietal resistance to whitebacked planthopper

M. N. Lal, S. K. Verma, G. C. Sachan, P. K. Pathuk, and J. S. Nanda, Entomology Department, G. B, Pant University of Agriculture and Technology, Pantnagar, U. P., India

Whitebacked planthopper (WBPH) Soga- tella furcifera (Horvath) regularly damages rice in Uttar Pradesh. The standard evaluation system was used to screen 531 rice varieties for WBPH resistance in the greenhouse. Thirty-six varieties were resistant (see table). Screening data showed that N22 with Wbph 1 gene for resistance to WBPH was not resistant. However, breeding lines IR13458-7-2-1-1-3-3 and IR17307-11-2-3-2 from N22 crosses showed resistant reaction. IRI5797-74- 1-3-2, derived from an IR2035-117-3 cross, was also resistant. The susceptibility

Rice resistance to yellow stem borer

M. Chandramohan and S. Chelliah, Tamil Nadu Agricultural University, Coimbatore, 641003, India

Rice varieties are being screened for resistance to yellow stem borer Scirpophaga incertulas (Walker) at the Paddy Breeding Station, Coimbatore, India. This species is a serious pest in double-cropped areas and causes deadhearts and whiteheads at crop vegetative and reproductive stages.

Field-collected moths were put in cages with potted rice plants to oviposit.

Emerging first-instar larvae were used to test varieties for resistance. Because varietal susceptibility varies with age, screening was done at seedling, tillering,


Other pests Rodent damage on some rice varieties at Aduthurai, India

G. Chakkaruvarthy, S. Uthamasamy, and K. M. Balasubramanian, Tamil Nadu Rice Research Institute, Adurhurai, India

The Indian mole rat Bunadicota ben- gulensis (Gray) and the grass rat Millur-

8 IRRN 8:2 (April 1983)

of N22 at Pantnagar may indicate the pre- TABLE CONTINUED sence of an inhibitory gene. Further in- vestigation is needed.

Average Resis- damage a tance b Variety

Whitebacked planthopper-resistant rice varieties, Pantnagar, India.

Variety Average Resis- damage a tance b

ARC5780 5.0 MR ARC5838 4.6 MR ARC6564 5.0 MR ARC6579 4.2 MR ARC6624 4.2 MR ARC10464 4.6 MR ARC11128 3.8 MR ARC11220 3.9 MR ARC11321 5.0 MR ARC11324 3.0 R Babawee 2.3 R Balmawee 1.0 R IET6288 2.2 R IR2415-90-4-3 3.0 R IR13384-79-2 4.7 MR IR13458-7-2-1-1-3-3 3.0 R IR13458-50-2-3-3-3-2 4.6 MR

IR15529-175-2-3-2 IR15795-199-3-3 IRl5797-74-1-3-2 IRI7307-11-2-3-2 IR17494-32-2-4 IR17496-2-25-1 IR1 339 KAU1717 KAU25100

Ptb 19 Ptb 21 P'tb 33 Rathu Heenati

RNR1576

Sinna Sivappu Suduru Samba

M22-33-3-1

RAU4000-105

RP1045-714-3-3

3.8 5.0 2.1 1.5 4.8 2.6 3.0 3.0 1.7 4.5 0.5 2.1 2.7 1.0 3.2 4.0 4.7 2.0 1.7

MR MR R R MR R R R R MR R R R R MR MR MR R R

a By the 1980 Standard Evaluation System for Rice scale. b R = resistant, MR = moderately resistant.

CONTINUED ON NEXT COLUMN

and reproductive stages.

rows in 50- × 40- × 10-cm seedling screening trays filled with soil. Twenty days after sowing one freshly emerged larva/ seedling was released. Trays were covered with a glass cage for 2 days to prevent the dispersal of the larvae, and to avoid predators.

Twenty-five days after germination 1 seedling/l0-cm pot was planted. When the plants were 40 days old, one freshly hatched larva/tiller was placed on the top- most auricle. Plants were covered with polyester cages and tests were replicated three times. Jaya was the susceptible check. Deadhearts were counted 7 and 10 days after release at seedling and vegeta-

Pregerminated seeds were sown in tive stages.

sowing, one larva was released/tiller and plants were covered with a cylindrical polyester cage. Ten days after release whiteheads were counted. Percent deadhearts and whiteheads was calculated by:

At reproductive stage, 70 days after

% deadhearts (whiteheads) in entry

% deadhearts (whiteheads) in susceptible check

Among the 170 varieties tested, W1263 and IR136-41-4 were moderately resistant at the seedling stage, and resistant at vegetative and reproductive stages. CO18, IR136-39-39, and Sornavazhai were moderately resistant at all stages.

× 100

Rodent damage to some rice varieties at Tamil Nadu, India a

Variety Damage (%)

Variety Damage (%)

Variety Damage (%)

IET5 74 2 0.0

AD3488 2.6 IET5852 1.4 IET5046 0.5 White Ponni 2.2 Co 25 0.9 Co 40 0.4 NLR9672 1.5 CR1009 0.7 TNAU15868 0.2 Co 38 1.5 Ponni 0.6

CONTINUED ON NEXT PAGE

dia meltada meltada (Gray) cause severe damage to the rice crop in Aduthurai. Rodents' preference for rice varieties was observed during 1981 kharif. Recorn- mended management practices were followed in 5- × 4-m test plots replicated 3 times.

Rodent damage was assessed 65 days after transplanting. Total tillers and rat cut tillers were counted on 20 hills selected at random along a transect through the middle of each plot.

Of the 57 varieties observed, IET5742 had no rat damage and 21 varieties had less than 5% damage (see table). Jaya, which is susceptible to many insect pests, also had the highest rodent damage (35.4%).


Deep water Screening for quick establishment and submergence tolerance at seedling stage

R. Thalkur, senior rice breeder, and R. K. Singh, assistant research officer, Plant Breeding and Genetics Department, Rajendra Agricultural University, Bihar College, Sabour, Bhagalpur, India

Ill-drained wetlands make up most of the riceland in Bihar. Although their natural soil fertility is high, they are affected by many stress conditions such as a sudden rise in water level in the transplanted fields because of the July-August rains. Crops are washed out and the percentage of stand is reduced. Transplanting must sometimes be delayed until mid- September, when yield recovery is margi- nal. Varieties with good seedling submergence tolerance and quick stand establishment are needed for these areas.

On 2 September 1980, 40-day-old seedlings of 48 F 5 cultures from the cross Borogar (deepwater)/IR8//BR14 (deepwater); 7 F 5 culture from Borogar/IR8; and 46 mixed cultures comprising local deepwater, wetland, and introduced materials were transplanted in a typical wetland field. Each culture had 6 rows of 22 plants/row and 1 seedling/hill transplanted at a 20- × 15-cm spacing. Two days later, water began to rise, reaching 40- to

TABLE CONTINUED

Variety

IET6441 IET5914 PY 1 IET6264 IET7046 IET6686 IET6987 Bhavani IET6290 AS781/1 IET6263 IET5882 ADT35 IET6261

Damage (%)

3.4 3.5 3.6 3.8 3.9 4.1 4.5 4.8 4.8 4.8 5.2 5.6 6.2 6.6

a Av of 3 replications.

Variety

IR20 TNAU20216 IET5975 IET6658 IET6272 IET6657 IET6666 IET5890

IET6265 Pankaj

IET6074 IET6212 IET7041 IET5883 Jagannath

Damage (%)

6.6 6.7 6.7 7.0 7.1 7.2 7.9 8.0 8.5 8.6 8.8 8.8 9.1 9.7 9.8

Variety

IET6276 IET6314 IET6271 IET6282 IET6466

IET6669 IET6279 IET6269 IET6144 IET3231 TM3802 IET6262 IET6010 Jaya IET5709

IET20-H 27-97

Damage (%)

10.0 10.4 10.8 11.4 12.3 12.7 12.8 13.5 14.5 15.2 15.5 15.8 16.0 21.4 35.4 44.4

50-cm depth. Only the leaf tips of a few cultures remained visible during this period; almost all plants were submerged.

When the water receded 10 days later, the surviving plants were counted. Many cultivars that looked dead were, in fact, alive and later gave shoots. Some also showed adventitious roots. Varietal differences in surviving stands varied from 0 to 66%. Twelve of the 48 cultures of Borogar/IR8//BR14 were wiped out; 10

had more than 20% survival. Six of the seven cultures of Borogar/IR8 had 27-47% survival. Among the deepwater types, only three — C183 (Akalbir), C180-6 (Singhra), and Parwapankh — had more than 20% survival. Locally adopted deepwater types such as Kabra, Bajra, Janeria, Borogar, Jagnathia, Pichar, and the introduced lines CN539, CN540, CN63, CN643, and CR1105 performed poorly. Five cultures were superior (see table).

Characteristic features of superior submergence-tolerant rice cultures. Bhagalpur, India.

Tillers/ Grain

(av no.) type Cultivar Cross Survival Feature plant Kernel

color (%)

1-246 Borogar/IR8//BR14 40 Dwarf 7.5 Short Red bold

56-19-22 Borogar/IR8//BR14 66 Medium 8.2 Short White dwarf bold or red

6-13-35 Borogar/IR8 45 Tall 8.0 Medium White bold

7-15-34 Borogar/lR8 47 Tall 9.7 Short White bold

C183 Pureline selections 42 Tall 5.8 Medium White from Akalbir bold

The International Rice Research Newsletter (IRRN) invites all scientists to contribute concise summaries of significant rice research for puhlication. Contributions should be limited to one or two pages and no more than two 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.

IRRN 8:2 (April 1983) 9

Relative elongation of deepwater rices

U. S. Singh and R. A. Pandey, Agricultu- ral Research Station (ARS), Chagharaghat, Bahraich 271901, Uttar Pradesh, India

Relative elongation of 14 deepwater rices at 1 and 2 months of submergence was studied in 3 replications at ARS, Chagha- raghat, during 1981 kharif. Five seeds were sown in clay pots filled with 4 kg of a 3:1 mixture of airdried soil and farmyard manure. After 1 month seedlings were thinned to 1 /pot. Three grams of urea were applied preplanting and 3 g diammonium phosphate were applied at 50 days when pots were transferred to deep water.

Height of the main culm to the highest auricle was recorded at 50 days. Plants were submerged in 50 cm water. Water level was raised 37 mm/day during the first month and 6 mm/day during the second month.

Nang Dumto, RP31-49-2/LMN920356, Boon Nakh, Saran Kraham/RP31-49-2/

Before submergence Jalmagna check,

LMN920349, and RP31-49-2/LMN920388

Relative elongation ability of deepwater rices, Ghagharaghat, India

Variety

Elongation

Height before (cm)

1-mo 2-mo submergence submergence

(cm) (cm)

Jalmagna (check) RP31-49-2/LMN920312 RP31-49-2/LMN920312-1 RP31-49-2fLMN920316-1 RP31-49-2/LMN920316-2 RP31-49-2/LMN920349 RP31-49-2/LMN920350 RP31-49-2/LMN920351 RP31-49-2/LMN920354 RP31-49-2/LMN920356 RP31-49-2/LMN920388 Nang Dumto Saran Kraham Boon Nahk

31 23 23 26 26 28 23 25 25 31 28 34 29 30

97 99

101 96 96

103 104 102 93 95 97

111 108 117

139 130 136 132 138 135 137 138 130 145 131 154 149 160

C. D. at 5% 4.2 6.9 7.3

were of similar, superior height (see table). After one month Boon Nahk, Nang Dumto, Saran Kraham, and RP31-49-2/ LMN920350 had elongation superior to that of Jalmagna. After 2 months Boon Nahk, Nang Dumto, and Saran Kraham remained superior.

All rices had adequate, but widely

varying, elongation ability. Strains with superior growth under normal conditions were not necessarily superior under submergence. Some varieties grew faster early in submergence, but growth rate slowed later, resulting in relatively poor total performance. Further studies of this type should be conducted.


Temperature tolerance Genetics of cold tolerance at rice reproductive stage

S. Acharya, senior research fellow, and K. D. Sharma, professor and head, Plant Breeding Department, H. P. Agricultural University, Palampur 176062, H. P., India

The genetics of cold tolerance in rice has not been adequately defined because of the complex nature of plant response to cold environments and lack of reliable methods for scoring such response.

Two sets of 21 treatments of a 6- parent diallel using IR3941-45-Plp 2B,

IR579, Himdhan, IR2637-44-2, Zenith, and IR30, and their 15 F1s, excluding reciprocals, were grown in a randomized block design with S replications. Fifteen- day-old seedlings, raised on sand in petri dishes, were transplanted in earthen pots filled with 2 parts soil, 1 part farmyard

Estimated general combining ability effects for cold tolerance, as measured through different character indices. a

Effective tillers/ Parent

Days to Panicle Panicle Spikelet Panicle Pollen Crude flower

Gelatinization weight length fertility exsertion fertility protein

Amylose temperature hill

IR3941-45-Plp 2B -0.74** -0.61 -0.83** IR579 1.82** -0.93** 2.79** Himdhan -0.77** -0.73** -2.21**

Zenith 2.08** 0.38 5.30** IR30 -0.98** -0.97** -1.75**

SE (gi)± 0.07 0.32 0.20

IR2637-44-2 -1.41** 2.86** -3.30**

SE (gi-gj)± 0.11 0.49 0.27

a *Significant at P = 0.05, **significant at P = 0.01.

-5.85** 11.07** -1.85** -7.56** 9.08* *

-4.98**

0.70

1.09

0.47** - 11.50** 0.99** 14.86**

-1.63** -4.15** -0.51** -7.22** 0.73** 13.50**

-0.05 -5.49**

0.12 0.59

0.19 0.91

-11.46** 12.46** -5.66**

-28.74** 38.31** -4.91**

1.23

1.90

-2.47** 4.31**

-1.16** -2.07** 3.48**

- 2.09**

0.13

0.20

-2.26**

- 1.02* 3.58**

2.65** 1.20**

-4.15**

0.45

0.69

-0.1 1

-3.70** 0.54*

1.16** 3.86**

-1.75**

0.26

0.40

-0.24 -0.10 -3.34** 0.33 2.69** 0.66**

0.1 7

0.25

10 IRRN 8:2 (April 1983)

Yield/ hill

manure, and 1 part sand. About 10 days before heading, one set of materials was transferred to a glasshouse chamber where temperature was maintained at 18°C. The other set was grown under normal temperature (30°C). Days to flower; effective tillers per hill; yield per hill; panicle weight, length, and exsertion; spikelet fertility; pollen fertility; crude protein and amylose, and gelatinization temperature in cold stress and normal conditions were recorded. Cold injury was calculated as the difference between normal and stress conditions, expressed as a percentage of the norm.

Analysis of combining ability showed the importance of additive and dominance gene action to cold tolerance inheritance for all indices studied. Dominance effects were stronger for all characters except panicle weight and spikelet fertility. Var-

iance component analysis yielded similar results.

Proportional values among genetic components suggested there are more dominant than recessive genes. Panicle exsertion and pollen fertility had asym- metrical dominant and recessive gene dis- tributions in the parents. Symmetrical distribution was observed for the remaining indices. Positive and negative alleles at loci showing dominance were asymmetrically distributed in the parents for all cold tolerance characters studied. Combining ability analysis and genetic component analysis showed overdomi- nance for all indices except panicle weight and spikelet fertility and pollen fertility.

IR3941-45-Plp 2B, Himdhan, IR2637- 44-2, and IR30 were the best general com- biners for cold tolerance (see table). Cros-

ses of IR3941-45-Plp 2B with Zenith and lR30; IR579 with Himdhan; and IR2637- 44-2 with Zenith were the most promising for incorporating cold tolerance. They re- presented all possible combinations between parents of high, average, and low general combining ability (gca). Of these crosses, IR3941-45-Plp 2B/IR30 involved both parents with high gca and can be exploited through recurrent selection.

ERRATUM

S. S. Malik. Gamma ray-induced semidwarf mutants in Basmati 370. IRRN 7 (6) (Dec 1982), page 4: In the column Scent in the table, No should be changed to Yes.

Pest management and control DISEASES

Purification and properties of grassy stunt-associated filamentous particles

H. Hibino, IRRI; T. Usugi and T. Tsuchizaki, Institute for Plant Virus Research, Tsukuba, Japan; M. Iwasaki, Kyushu National Agricultural Experi- mental Station, Japan; and S. Izumi, Kagoshima Prefectural Agricultural Experimental Station, Japan

Filamentous (6-8 nm diameter) and isometric (18-20 nm diameter) virus-like particles were found in a partially purified fraction of rice grassy stunt (GSV) infected rice plants. Filamentous particles were numerous in the fraction and isometric particles were scarce.

Filamentous particles were purified by clarification with Mg-bentonite and CCl4, PEG treatment, and sucrose density-gradient centrifugation. Electron microscopy of the purified fraction revealed numerous filamentous particles and a few contaminants (see figure). Some filaments were circular and 200- 2,400 nm long. Length distribution peaked at 1,000-1,300 nm. The UV absorption spectrum of the purified fraction was typical of a nucleoprotein

— maximum absorbance 260 nm, minimum absorbance 247 nm, and 260/280 ratio was 1.28 ± 0.3. Filamentous particles had RNA and single coat protein of 31,000 daltons.

Antiserum was obtained by injecting rabbits with the purified filamentous particles. In the precipitin ring interface test, titer against purified filaments was 1:1280. A filamentous antigen was detec- ted in RGS-infected leaf and RGS- exposed brown planthopper extracts diluted 1/4096 and 1/1024, respectively, by a latex agglutination test using the antiserum. The antiserum did not react

with planthopper and virus-free leaf extracts.

Purified filamentous particles were injected into the abdomen of second- instar nymphs of the brown planthopper to test infectivity of the particles. None of the injected brown planthoppers became infective.

Specific reaction between the antiserum and extracts of GSV-infected leaves and exposed insect vectors sug- gests that the nucleoprotein may cause GSV. Relations between the nucleoprotein and isometric particles remain to be clarified.

IRRN 8:2 (April 1983) 11

Electron micrograph of puri fied filamentous particles- X 150,000

Rice plants with rice tungro virus-like (RTV) symptoms were observed at IRRI experimental farm (Laguna) and in Koronadal (South Cotabato). Infected plants showed stunting, leaf yellowing,

and spreading growth. Symptoms varied according to variety and age of plant when infected. Leaves of some varieties were mottled or striped and had irregular rusty blotches. Plants infected at seedling stage showed profuse tillering similar to that caused by rice grassy stunt (GSV) and usually died prematurely. Plants infected at later stages developed symptoms indistinguishable from those caused by

Unknown disease of rice transmitted by the brown planthopper in the Philippines

A new disease symptom was observed on BR9 and other varieties in fields at BRRI farm in Joydebpur in July 1982. Outer leaf sheaths near the lower part of the stem showed brownish blotching or banding. The 5-cm band usually circled the entire sheath wrapping the culm. Outer leaves died. As plants matured black pycnidia with protruding ostioles and setae emerged from the sheath tissues. Similar symptoms were described as “sheath blotch” caused by Pyrenochaeta oryzae by Miyake (1910).

The fungus was isolated from diseased tissue and produced pycnidia and pyc- nidiospores in 15- to 20-day-old cultures. The fungus was Pyrenochaeta sp. To complete Koch’s postulates, BR9 plants were inoculated at booting stage with the

fungus. Blocks were attached to slightly wounded sheaths with scotch tape, and the whole plant was covered with a poly- ethylene bag for 3 days. Water-soaked lesions and brownish discoloration and banding similar to those found in the field were produced 7-10 days after inoculation (see figure). Pyrenochaeta sp. was also reisolated from the artificially inoculated plants, confirming the cause of the disease.

A survey was conducted on the BRRI farm to determine level of sheath blotch occurrence on different varieties. Of 178 entries examined, 152 were infected. The most susceptible were: BR9, BK194-1-2- 1-3-2, BR593-647-25-2, BR1045-188-2-1, BKNFR76001-3-4-1-4-1, IR5, IR9288-B- B-B240-2, IR4744-295-2-3, IR9852-22-3, IR11297-158-1-1, IR13539-100-2-2-2-3, IR19661-131-1-3-1-3, IR5889-8-1-4-1-0, IR7732-1-198-RGA-BR(B)-B. IR9288-1- 48-RGA-BR(B)-B, IR7732-1-87-RGA- BR(B)-B, DWCB-464-B, and DWCT134-3- 1-5.

Sheath blotch of rice in Bangladesh

A. K. M. Shahjahan, H. U. Ahmed, and S. A. Miah, Bangladesh Rice Research institute (BRRI), Joydebpur, Dacca

Serological relations between rice grassy stunt and the unknown disease of rice transmitted by Nilaparvata lugens (Stål) in the Philippines

H. Hibino and P. Q. Cabauatan, IRRI

Serological tests were conducted to determine the relationship between the causal viruses of rice grassy stunt (GSV) and the unknown disease of rice transmitted by brown planthopper N. lugens. A latex agglutination test was made using an antiserum to GSV-associated filamentous particles prepared in Japan (1982).

Latex suspension (Difco Bacto Latex 0.81) was mixed with tris-HCl buffer containing antiserum at a 1/1,000 dilution and allowed to stand for 30 minutes. The coated latex suspension was washed and stored for use in the agglutination test. Sap of TN1 plants artificially infected with either the unknown disease or GSV was diluted 2 times. Diluted sap was mixed with the coated latex suspension and shaken for 30 minutes. Reaction was judged visually or under a light micro- scope based on clumping of latex particles. Positive reactions were obtained from sap of plants infected with the un-

12 IRRN 8:2 (April 1983)

Typical symptoms of sheath blotch of rice produced by artificial inoculation of BR9 with Pyrenochaeta sp.

Reaction of rice grassy stunt virus (GSV) and the unknown virus from the Philippines to GSV antiserum from Japan using the latex agglutination technique.

Source of

infection 1:10 1:20 1:40 1:80 1:160 1:320 1:640 1:1280 1:2560 1:5120

Reaction at given sap dilution

GSV + + + + + + + + + + Unknown

Virus-free - - - virus + + + + + + + + - -

- - - - - - -

known disease up to 1 : 1280 dilution. The sap from GSV-infected plants gave positive reaction up to 1 : 5 120 (see table). Positive results were also obtained from the sap of 19 of 24 naturally infected plants showing tungro-like symptoms. Results indicate that the unknown virus and GSV in Japan and the Philippines is

serologically related. The unknown virus is therefore identified as a strain of GSV because of their serological relationship and similarity in their symptomatology and virus-vector interactions. We pro- pose that the new strain be designated as strain 2 (GSV-2) and the former type be designated strain 1 (GSV-1).

P. Q. Cabauatan and H. Hibino, IRRI

RTV infection. Such symptoms were Table 1. Reaction of Oryza nivara to grassy stunt (GSV) and to the unknown disease, IRRI. most common.

The disease is transmitted by brown planthopper Nilaparvata lugens. The incu- bation period of the causal agent in the insect was 5-21 days, usually 6-8 days. Five to 30% of the insects were active transmitters. The disease was not transmitted by sap, seeds, or soil or by 368 green leafhoppers Nephotettix virescens used to inoculate about 3,000 seedlings.

Disease symptoms were observed 7-14 days after inoculation of 7-day-old Tai- chung Native l (TNl) seedlings. Infected plants were yellow or pale yellow, even when fertilized adequately. TN1 plants infected at 2 months had RTV-like symptoms similar to those of naturally infected plants.

Although the unknown disease is similar to GSV, the two diseases differ: 1) the RTV-like symptom has never been described for GSV; 2) the disease is often lethal, particularly when plants are infected at early growth stages; and 3) Oryza nivara, the source of the resistance gene against GSV, is susceptible to the unknown disease (Table 1). Consequently, IR varieties with O. nivara genes for resistance to GSV are also susceptible (Table 2). These differences indicate the unknown disease may be a new virus disease or a strain of GSV.

GSV Unknown disease

Trial Plants (no.) Infection (%)

Plants (no.) Infection

Inoculated Infected Inoculated Infected (70)

I a 10 0 0 14 14 100 II a 11 0 0 11 9 82 III b 84 2 2.4 31 29 93.5

a Inoculated at 3 weeks old using 15-20 insects/seedling. b Inoculated using the mass screening method for GSV.

Table 2. Reaction of IR varieties to grassy stunt (GSV) and to the unknown disease, IRRI.

GSV a Unknown disease b

Variety Plants (no.) Infection Plants (no.) Infection

Inoculated Infected (%) Inoculated Infected (%)

IR28 IR29 IR30 IR32 IR34 IR36 IR38 IR40 IR42 IR43 IR44 IR45 IR46 IR48 IR50 IR52 IR54

3 80 183 309 548 489

4467 367 308

4225 203 388 175 587 342 560 264 41

127 48 81

156 101

1546 73 57

1363 37 72 16

114 35 91 27

3

33.4 26.2 26.2 28.5 20.7 34.6 19.9 18.5 32.3 18.2 18.6

9.1 19.4 10.2 16.3 10.2

7.3

83 73 77 87 65 97 75 58

191 64 94 85 87 77 92 75 72

72 66 64 78 59 87 65 49

183 53 81 82 78 67 81 69 69

86.8 90.4 83.1 89.7 90.8 89.7 86.7 84.5 95.8 82.8 86.2 96.5 89.7 87.0 88.0 92.0 95.8

a Combined data for GSV screening for 1980 and 1981. b Total of 2 trials (2 replications/trial).

Pest management and control INSECTS

Leaffolder outbreak in tarai belt of Nepal

S. B. Pradhan, assistant entomologist, and B. B. Shahi, rice coordinator, National Rice Improvement Program (NRIP), Parwanipur Agricultural Station, Birgunj, Nepal

The rice leaffolder Cnaphalocrocis medinalis Guenée has recently become a serious rice pest in Nepal. In 1977, it became epidemic in some tarai districts and in hilly areas. In 1978, leaffolder incidence was high at Janakpur, Bara, and Parsa, and in some hilly areas around Kathmandu Valley. In 1979-80, infestation was high in the first crop at the Par- wanipur Station and in adjacent areas.

The insect first appears in May and folded. stays until November. Its life cycle is Attack at early tillering stage was generally completed within 25-30 days; serious and the extent of the yield reduc- cycles can be observed by the appearance tion it caused should be studied. of large moth populations at 1 -month intervals. In a rice season, 4-5 generations are comp1eted. A June 1980 field survey Brown planthopper resurgence on IR36 showed pest incidence in most of the tarai; “hot pockets” were Janakpur,

in Mindanao, Philippines

Kankai, Bara, and Parsa. Leaffolder incidence was heavy at Hardinath Agricultural Farm and in surrounding areas in Janakpur where about two-thirds of the leaves in infested fields were folded. Most of the fields were totally white and papery because the chlorophyll of the rice plants was completely eaten off. In some fields about 90% of the leaves were

Cornelio A. Peralta, Wilfredo S. Fontanilla, and Lorenza S. Ferrer, Regional Crop Protection Center, Tacurong Sultan Kudarat, Philippines

During a baseline field trial for insect control recommendations in Sultan Kudarat Province, up to 5% brown planthopper (BPH) hopperburned hills

IRRN 8:2 (April 1983) 13

BPH data from Mindanao, Phil- ippines, show BPH resurgence on IR36.

Cytological variations among brown planthopper biotypes 1, 2, and 3

R. C. Saxena, associate entomologist, IRRI, and principal research scientist, International Centre of Insect Physiology and Ecology, P. O. Box 30772, Nairobi, Kenya, and A. A. Barrion, research scholar, IRRI

Cytological studies of the meiotic chromosomes of brown planthopper (BPH) biotypes 1 and 2 maintained as stock cultures at IRRI for several years revealed that meioses I and II were reductional and equational for all components of the species’ genome. Similar phenomena were observed for biotype 3. Investigations used primary spermatocytes of newly emerged brachypterous males to charac-

terize the nuclei and chromosomes and determine their morphometrics and be- havior during the sequential stages of the first meiosis.

Salient variations in nuclear and chromosomal measurements of biotypes 1, 2, and 3 during substages of prophase I are shown in the table.

During metaphase I chromosomal be- havior showed clumping or clustering of highly condensed and shortened autosomes at the equatorial portion of the reproductive cell and separation of the highly heterochromatic synapsed sex chromosomes from the autosomal grouping. The following variations in the three biotypes were noteworthy:

1. Biotype 1 had the highest number of metaphase I cells; biotype 2 had the least cells.

14 IRRN 8:2 (April 1983)

were observed in some nearly mature plots of IR36. IR36 is BPH resistant. The following data were collected from light traps, weekly field counts, and insecticide use records (see figure).

peaked 7 to 9 weeks after transplanting Final field counts showed that all plots sprayed with the recommended mixture of chlorpyrifos and BPMC during this peak (treatments A, B, D, G) had higher BPH population densities than those not sprayed. Plots sprayed before and during the peak (A, D, G) had higher densities than those sprayed either before or during the peak (B, C, E, F). Mean population density exceeded 95 BPH/hill in one field. Other studies showed that neighboring farm fields contained 15 predators and parasite species known to feed on BPH.

We concluded that destruction of natural enemies allowed BPH to flourish in sprayed plots. Populations in unsprayed plots never exceeded the 20/hill economic action threshold.

This is the first report of BPH resurgence and subsequent hopperburn on certified IR36 after 6 years of widespread planting in the Philippines, indicating the evolution of a host plant resistance- breaking phenotype. The heavier the insecticide use the higher the multiplica- tion of BPH able to feed on IR36. This may contribute to biotype emergence.

Light trap data showed BPH numbers

2. Biotypes 1 and 3 had two kinds of metaphase I cells – cells with sex chromosomes isolated from autosomes and cells with both chromosome types grouped together; biotype 2 had only the first type of cells.

chromosomes from autosomal grouping was greatest for biotype 2, almost twice that of biotype 1, while biotype 3 ranked next.

4. More cells with combined autosomes and sex chromosomes were observed in biotype 1 than in biotype 3. Intra- and interchiasmatic connections were higher in biotype 1 than in biotype 3 homologues.

5. Sex chromosomes of the three biotypes varied in length and width.

3. The average distance of the sex

Rice thrips Baliothrips biformis (Bagnall) is a minor rice pest in the Punjab. It usually attacks the late transplanted crop. BHC 10% dust applied at 10 kg/ha (2.5 kg ai/ha) is the only recommended control.

Foliar insecticides for thrips control were field-tested at the Regional Research Station at Gurdaspur. Thirty-day-old PR103 seedlings were transplanted in 20-m 2 plots in a randomized block design with 3 replications. They were sprayed with 10 insecticides 15 days after transplanting. BHC was included as a check.

Thrips/5 hills were recorded before treatment and 3 and 7 days after treatment (DAT). Population reduction was calculated as:

Biotype 2 had the longest chromosomes and biotype 1 had the shortest. Biotype 2 had the widest X and Y chromosomes, while biotype 1 and 3 measurements were almost equal.

During anaphase I measurements of the chromosome clumps at the two poles of the cells showed the lengths and widths of chromosome groupings in biotype 2 differed significantly from those of biotype 1 but not from biotype 3.

At telophase I the groupings of chromosomes at two opposite poles of the cells were almost equal for all three biotypes.

Chromosomal aberrations, such as loose pairings of paired homologous biva- lents as well as fragmentations of chromosomal deletions occurred more frequently among biotype 1 individuals, followed by biotype 3.

Rice thrips control by foliar insecticides

D. P. Singh, G. S. Dhaliwal, and Juswant Singh, Punjab Agricultural University, Rice Research Station, Kapurthala 144601, Punjab, India

Variations a in nuclear and chromosome measurements of brown planthopper biotypes 1, 2, and 3 during prophase. IRRI, 1981-82.

Prophase I substages Biotype 1 Biotype 2 Biotype 3

Leptonema Nuclei: aml and amw ) ns 31.75µ and 26.50µ, 29.90µ and 24.00µ, 30.50µ and 24.75µ

highest lowest intermediate

Zygonema Autosomes Sex chromosome )

Pachynema Autosomes rml ) 11.11 mm, lowest 12.43 mm, inter- 13.17 mm, highest

Sex chromosome rml ) 6.50 mm, lowest 9.00 mm, highest 7.00 mm, inter-

) no difference no difference no difference

) ns mediate

mediate

Diplonema Autosomes aml b 5.92µ, lowest 8.08,µ highest 7.08µ, intermediate Sex chromosome aml 7.50µ 5.00µ 5.00µ

Diakinesis Chromosomes aml c 4.35µ, highest 3.77µ, intermediate 3.39µ, lowest

a aml = absolute mean length, amw = absolute mean width, rml = relative mean length, ns = not significant at 5% level by analysis of variance and Duncan’s multiple range test. b Biotype 1 significantly different from biotypes 2 and 3; biotypes 2 and 3 not significantly different from each other at 5% level by analysis of variance and Duncan’s multiple range test. c Biotype 1 significantly different from biotype 3 but not from biotype 2; biotype 2 not significantly different from biotype 3 at 5% level by analysis of variance and Duncan’s multiple range test.

Efficacy of foliar insecticides for control of rice thrips, Gurdaspur, Punjab, India, 1982.

Population Percent reduction after Treatment a before treatment 3 days

(no./5 hills) b 7 days c

BHC 110 88 b 99 Chlorpyrifos 63 77 c 99 Demetono-methyl 70 96 a 97 Endosulfan 93 92 ab 98 Fenthion 52 93 ab 99 Fenitrothion 79 93 ab 99 Methyl parathion 59 87 b 97 Monocrotophos 84 92 ab 98 Phosaione 60 80 c 100 Phosphamidon 64 90 ab 99 Quinalphos 57 93 ab 95 Untreated check a BHC was applied at 2.5 kg ai/ha; all other insecticides were used at 0.5 kg ai/ha. b Figures followed

68 – –

by the same letter in a column are not significantly different at 5% level. c All treatments were significantly different from the untreated check but did not differ from each other.

Insects counted per sample × Insects counted in the

Insects counted per sample × Insects counted in the unit after treatment control before treatment

Percent reduction = × 100

unit before treatment control after treatment

Demeton-o-methyl, quinalphos, fen- (see table). Phosalone and chlorpyrifos thion, fenitrothion, monocrotophos, en- were least effective. However, all in- dosulfan, and phosphamidon controlled secticides reduced thrips population by thrips better than BHC dust at 3 DAT more than 95%.

The International Rice Research Newsletter (IRRN) invites all scientist to contribute concise summaries of significant rice reseach for publication. Contributions should be limited to one or two pages and no more than two short tables, figures, or photographs. Contributions are subject to ending and abridgement to meet space limitations. Authors will be identified by name title, and research organization.

IRRN 8:2 (April 1983) 15

Pest management and control WEEDS

Effect of rice planting date and density on weed growth

R. C. Gautam and K. C. Sharma, Agronomy Department. G. B. Pant University of Agriculture and Technology, Pantnagar 263145, Uttar Pradesh, India

Weed growth was observed in an experiment during kharif (wet season) 1975, 1976, and 1977 at the Crop Research Centre (29º N, 79.3º E, 243.84 m alti- tude). Treatment 1 had shortduration varieties Ratna, Rasi, and Cauvery planted 10 June. Treatment 2 had Ratna planted 20 June, Rasi planted 5 July, and Cauvery planted 10 July so all varieties would mature at the same time. Medium-duration variety Jaya was planted 10 June to mature with treatment 2. Treatments were tested at plant density of 25, 100, and 400 hills/m 2 .

Increasing plant density from 25 to 100 hills/ m2 decreased weed dry weight and intensity significantly (see table). Planting dates did not influence weed weight. The interaction of planting date and plant density significantly affected weed growth.

Weed growth (av of 3 seasons) in rice planted at different dates and plant densities, Uttar Pra- desh, India.

Weed growth

weight (no. of (g/m 2 ) weeds/m 2 )

Treatment Dry Intensity

Planting scheme Jaya, 10 June 15.6 8.9 Ratna, 10 June 15.5 9.1 Rasi, 10 June 14.9 10.7 Cauvery, 10 June 15.3 10.1 Ratna, 20 June 14.7 9.7 Rasi, 5 July 14.8 10.1 Cauvery, 10 July 14.4 9.7

S.Em ± 0.8 0.2 C.D. (P = 0.05) ns 0.7

Plant density (hills/m 2 ) 400 100

25

2.6 1.9 10.1 10.7 32.4 16.6

S.Em ± 0.6 0.3 C.D. (P = 0.05) 1.8 0.9

Effect of nitrogen fertilizer and weed management on performance of four domized complete block design with

rice varieties in Sudan Gezira four replications. Medium-maturing varieties IR2035-

242-1 and IR2053-206-1-3 outyielded George I. Ghobrial, director, Kenana Re- search Station, Agricultural Research early-maturing IR2061-552 and IR1561- Corporation, Abu Naama, Sudan 228-3-3. Under good weed management,

however, grain yields were similar. Grain Low soil nitrogen content and severe upland weed infestation are major con- straints to high dry-seeded rice yields in Sudan Gezira. A field study at Gezira Re- search Station in 1980 evaluated grain yield of 4 rice varieties (see table) with different plant height and maturity, and grown at 2 levels of nitrogen (70 and 140 kg N/ha) under poor, medium, and good weed management levels. Twenty- four treatments were arranged in a ran-

yield of early-maturing rices was substantially reduced by poor weed manage. ment.

Nitrogen level significantly affected grain yield. Application of 140 kg N/ha increased grain yields 19-30% over those obtained with 70 kg N/ha, depending on the variety. Grain yield was consistently and progressively increased with better weed management. Unrestricted weed growth significantly decreased number

Effect of nitrogen levels and weed management on grain yields and yield components of four rice varieties at Sudan Gezira, 1980.

Weed Plant ht Grain Panicles Grains 1,000-

(g) N (kg/ha) management yield (cm)

(t/ha) (no./m 2 ) (no./panicle) grain wt

IR1561-228-3-3 (early maturity, short stature) 70 Poor 66 0.6 282 53 70

20.4 Medium 63 2.7 342 62 20.1

70 Good7 70 3.4 369 60 140

19.7 Poor 66 0.9 267 61 20.0

140 Medium 70 2.6 329 58 19.9 140 Good 72 4.9 396 76 19.8

IR2061-552 (early maturity, medium stature) 70 Poor 72 0.7 254 43 20.9 70 Medium 75 2.2 342 58 70

21.2 Good 82 3.2 367 62

140 21.5

Poor 78 0.5 255 52 22.7 140 Medium 78 2.1 329 65 140

21.2 Good 88 4.0 374 61 21.9

IR2035-242-1 (medium maturity, short stature) 70 Poor 65 1.5 284 56 22.1 70 Medium 68 2.7 342 67 21.8 70 Good 69 3.9 355 65 22.7

140 Poor 77 2.1 304 66 140

22.4 Medium 74 4.1 382 69 23.1

140 Good 79 4.9 392 73 22.5

IR2053-206-1-3 (medium maturity, medium stature)

70 Poor 84 1.6 294 75 23.3 70 Medium 86 2.8 332 80 23.3 70 Good 84 3.5 319 83 23.2

140 Poor 85 1.7 291 73 23.6 140 Medium 95 4.0 366 83 23.9 140 Good 99 4.8 472 92 23.5

16 IRRN 8:2 (April 1983)

Age of dhaincha, green matter, and nitrogen economy in rice

C. S. Khind, O. P. Meelu, and Viraj Beri, Soils Department, Punjab Agricultural Uni- versity (PAU), Ludhiana, India

In recent work at the PAU farm, bury- ing 2-month-old dhaincha (Sesbania aculeata) 1 day before transplanting saved up to 120 kg N/ ha. But the period for raising a dhaincha crop varies with time of rice transplanting, generally spread over almost a month in Ludhiana.

The effect of age of dhaincha on amount of green matter added and N economy was tested in kharif 1981. Soil of the experimental plot was loamy sand (Typic Ustochrept) with a percolation rate of 6 mm/ hour. It had pH 8.4, EC 0.15 mmho/cm, 0.34% organic carbon, 0.06% N, 8 µg/gram KCl-extractable NH 4

+ -N, and 8 µ/gram NO 3 -N. Dhaincha was sown at 15-day inter-

vals from 3 May to 3 June to attain 60, 45, and 30-day-old crops at rice transplanting. Phosphorus at 60 kg P 2 O 5 / ha was applied at sowing. Check plots

November (northeast monsoon season). Almost no rain falls from January to April. Rice, in wetland and dryland culture, is the major crop. Groundnut and millets also are grown. Weed problems are more severe in drylands than in wetlands. Dry weather from January to April favors the spread of dryland weed seeds that germinate when rains begin in July- August. Rainfed rice grown during July- August face serious weed competition. Weeds that grow during the fallow season cause weeds to spread in wetlands.

Soil and crop management

A sound knowledge of weed flora and their possible effects on a crop is essential

when planning weed control measures. Published reports on flora are available, but weed flora on agricultural lands changes. We have compiled a list of all wetland and dryland weeds that grow at PES Tirur (see table).

Tirur receives 1,200 mm average -an- nual rainfall, most of it during September-

J. Venkatakrishnan, P. Vivekanandan, and M. Ramachandran, Paddy Experiment Station (PES), Tirur – 602025, Tamil Nadu, India

of tillers and panicles per unit area, and reduced number of filled spikelets per panicle. Regardless of the rice variety used,

good weed control is essential to obtain high grain yield. It is particularly important to weed early-maturing varieties early to minimize yield reduction. The

study also indicated that application of nitrogen fertilizer can increase yields of dry-seeded rice in weed-free conditions,

Weeds of Chingleput district, Tamil Nadu

Agricultural weeds of Tirur, India.

Dryland weeds

Trianthema portulacastrum Linn.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Aizoaceae Amaranthus viridis Linn.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Amaranthaceae Digera arvensis Forsk. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Amaranthaceae Gomphrenn celosioides Mart. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Amaranthaceae Acanthospermum hispidum Dc. (Linn.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae Eclipta alba (Linn.) Hassk.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae

Flaveria australasica Hook. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae Lactuca runcinata Dc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae Tridax procumbens Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae Vernonia cinerea (Linn.) Less.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae Vicoa indica Dc.. Asteraceae

Erigeron asteroides Roxb. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Heliotropium indicum Linn.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boraginaceae Trichodesmo indicum R. Br.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Boraginaceae Eleome viscosa Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Capparidaceae Gynandropsis pentaphylla (Linn.) Dc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Capparidaceae Evolvulus alsinoides (Linn.) Linn.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Convolvulaceae Cyperus rotundus Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cyperaceae Fimbristylis littoralis Gaudich. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cyperaceae Euphorbia hirta Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Euphorbiaceae Phyllanthus niruri Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Euphorbiaceae Glinus oppositifolius Linn. A. Dc. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Molluginaceae Boerhavia diffusa Linn.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Nyctaginaceae Dactyloctenium aegyptium (Linn.) Beauv.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Poaceae Echinochloa colona (Linn.) Link.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Poaceae Eragrostis interrupta (Lam.) Doell. var. Koenigii. Stapf . . . . . . . . . . . . . . . . . . . . . . Poaceae Panicumrepens Linn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Poaceae Sporobolus coromandelianus (Retz.) Kunth. . . . . . . . . . . . . . . . . . . . . . . . . . . . .Poaceae Portulaca oleracea Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Portulacaceae Hedyotis umbellata Linn. Lam. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rubiaceae Rysanthes veronicaefolia Urban. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scrophulariaceae Physalis minima Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solanaceae Corchorus olitorius Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tiliaceae

Wetland weeds

Eclipta alba (Linn.) Hassk.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Asteraceae Cyperus bulbosus Vahl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Cyperaceae Cyperus rotundus Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cyperaceae Fimbristylis miliaceae (Linn.) Vahl. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cyperaceae Bergia capensis Linn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Elatinaceae Spirodela polyrhiza (Linn.) Schleid. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lemnaceae Ammannia baccifera Linn.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lythraceae Rotala densiflora (Roth.) Koehne. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lythraceae Cynodon dactylon (L. Rich.) Pers. Poaceae Echinochloa colona (Linn.) Link.. Poaceae Panicum repens Linn.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Poaceae Sphenoclea zeylanica Gaertn. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sphenocleaceae

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

IRRN 8:2 (April 1983) 17

Effect of age of dhaincha on green and dry matter production and nitrogen added, Ludhi- ana, India. Age of Green dhaincha matter matter (days) (t/ha) (t/ha)

Dry N added (kg/ha)

30 1.6 0.23 8.3 45 15.6 2.03 57.9 60 28.9 5.58 132.0

without dhaincha received basal P applied to rice. The dhaincha crops were buried one day before transplanting on 4 July.

Amount of green matter, dry matter, and N added increased with increasing dhaincha age (see table). In effect on yield, 60-day-old dhaincha alone was equal to 120 kg N/ ha applied as urea; 45-day-old dhaincha was equal to 60 kg N/ ha; 30-day-old dhaincha did not increase yield substantially (see figure).

Improvement of crop stand in flooded rice fields

B. B. Reddy, B. C. Ghosh, and M. M. Panda, Central Rice Research Institute, Cuttack 753006 Orissa, India

Direct-seeded rice fields inundated soon after seeding — not infrequent in rainfed lowlands — show suboptimal stands. In controlled greenhouse investigations on improving the germination and crop stand for such situations, seeds soaked in a 1% solution of oxidizing chemicals such as hydrogen peroxide, potassium permanganate, or potassium dichromate for 24 hours were sown in moist soil and immediately flooded with 10, 20, and 40 cm water.

Seeds soaked in hydrogen peroxide and potassium permanganate showed higher germination (90-95%) under different floodwater depths. Seeds soaked in potassium dichromate had drastically reduced germination (40-50%). Seeds soaked in hydrogen peroxide produced vigorous seedlings that emerged rapidly, even from 40-cm-deep floodwater.

The study indicates the possibility of improving crop stands in direct-sown flooded ricefields by soaking the seed in hydrogen peroxide and potassium permanganate.

18 IRRN 8:2 (April 1983)

Effect of azolla manuring with nitrogen fertilization

S. Srinivasan, Paddy Experiment Station, Aduthurai, India

The effect on rice grain yield of incorporating azolla into soil fertilized with nitrogen was studied in a field trial during 1979 rabi. The azolla levels tested were 0, 10, 20, and 30 t/ha; the N fertilizer levels, 0, 25, 50, 75, and 100 kg/ha; and the rice variety, ADT 31. Azolla levels formed the main treatment and nitrogen levels, the subtreatment. The treatments were repli-

Effect of azolla manuring along with nitrogen applications on grain yield of ADT 31, 1979 rabi, Aduthurai, India

Grain yield (t/ha) N level with azolla incorporated at Mean (kg/ha) 0 10 20 30 (N levels)

t/ha t/ha t/ha t/ha

0 3.4 3.8 4.2 4.6 4.0 25 3.8 4.4 4.7 5.0 4.5 50 4.2 4.7 5.3 5.6 4.9 75 4.5 5.3 5.8 6.1 5.4

100 5.0 6.0 6.4 6.8 6.0 Mean

(azolla levels) 4.2 4.8 5.3 5.4

Azolla levels N levels Interaction

C.D. 0.3 0.2 N.S.

Effect of age of dhaincha green manure on N economy in rice. Lud- hiana, India.

cated twice. Azolla was incorporated 1 week before planting; nitrogen as urea was applied in one basal dose. P 2 O 5 and K 2 O at 50 kg/ha were applied just before planting. The addition of azolla at all levels and of nitrogen at all levels gave significantly higher yields (see table).

Performance of rice transplanted under nonpuddled rainfed conditions

Y. S. Veeraraja Urs, junior agronomist, A. P. Vishwanath, research assistant, and M. A. Singlachar, rice agronomist, University of Agricultural Sciences, Regional Research Station, Mandya 571405, India

Ragi Eleusine coracana G., an important millet crop of Karnataka, is transplanted on the sides of ridges, then irrigated. A study was conducted to determine whether like ragi, rice could be transplanted under nonpuddled conditions and whether the subsequent rice crop could be grown under rainfed conditions, and given protective irrigation where necessary. A successful crop under these conditions would mean considerable water savings.

The test field was tilled during the early rains of the season. Ridges 20 cm

wide and furrows 30 cm wide were prepared. The field was irrigated to capacity. Thirty-day-old seedlings of 8 rice cultivars (see table) were transplanted on the sides of the ridges at 30- × 10-cm spacing with 2-3 seedlings/hill, in a randomized block design with 6 replications.

A basal application of 50 kg N/ha, 13 kg P/ha, and 30 kg K/ha was broadcast before ridges and furrows were prepared. Nitrogen at 25 kg/ha was applied in a band 5 cm away from planted rows at 20 and 45 days after transplanting. The crop was hand-weeded twice during

Foliar spraying Eichhornia inoculum and incorporation of Eichhornia and Ipomoea green leaves as supplemental nitrogen sources

Y. Yogeswara Rao, Wajid Ali Mirza, and C. Subbi Reddy, College Farm, Rajendra- nagar, Hyderabad, India

The aquatic weeds Eichhornia crassipes and Ipomoea carnea, unlike conventional green leaf manures, are abundant. An experiment was conducted in a randomized block design, replicated four times, on the College Farm, Rajendranagar, in the 1977 wet season to determine the effect of Eichhornia inoculum spraying and Eichhornia and Ipomoea green leaf incorporation in the nitrogen economy of rice. One hundred milliliters of Eichhornia spray solution with a count of 23.1 × 10 9 /ml was diluted 10 times and sprayed in each 13.5-m 2 plot. In treatments with 2% urea spray, 1,000 ml of 2% urea solution was sprayed in each plot.

Grain yield was highest (4.1 t/ha) in the treatment with 100 kg N/ha (see table). It was on par with the yields in treatments that received 60 kg N/ha + Eichhornia leaves; 60 kg N/ha +Ipomoea leaves, and with 60 kg N/ha + 2% urea

Fertilizer usage and productivity of aus, aman, and boro rice

R. L. Sugar, scientist (Extension), Jute Agri- cultural Research Institute (ICAR), Bar- rackpore, and G. L. Ray, assistant director of Agricultural Extension, Bidhan Chandra Krishi Viswavidyalaya, West Bengal, India

Performance of rice cultivars transplanted under nonpuddled conditions. Mandya, India, 1980 kharif (wet season).

Duration Grain yield (t/ha)

Cultivar (days)

Rasi 125 4.4 IR20 150 3.7 Mangala 110 3.6 IRAT 2 150 3.5 Jaya 160 3.2 IRAT 10 144 3.2 Lagore 144 2.8 IRAT 13 116 2.0

CD (0.05) 0.11 CV (%) 29

the early stages of crop growth. A fair distribution of rains during the season made protective irrigation unnecessary.

Results indicated that, of the eight rices tested, Rasi recorded the significantly highest yield, followed by IR20 and Mangala (see table). These rices had early and good stand establishment, satisfactory canopy cover with high panicle number, and low spikelet sterility. The rice yields obtained were very competitive with those of ragi grown under similar conditions.

Effect of Eichhornia inoculum spray and leaf incorporation of Eichhornia and Ipomoea with nitrogen application on rice yields. Rajendranagar, Hyderabad, India.

Grain Straw

Treatment Increase (%) Increase (%)

Yield over yield Yield over yield (t/ha) with (t/ha) with

60 kg N/ha 60 kg N/ha

100 kg N/ha

60 kg N/ha + Ipomoea leaf incorporation at 10 t/ha

60 kg N/ha + Eichhornia leaf incorporation at 10 t/ha

60 kg N/ha + 2% urea solution spray

60 kg N/ha + Eichhornia inoculum spray

60 kg N/ha + 2% urea spray + Eichhornia inoculum spray

60 kg N/ha

C.D. at 5%

4.1

3.9

3.8

3.8

3.7

3.5

3.3

0.4

24

18

15

15

12

6

–

–

4.7

4.2

4.2

3.8

3.5

3.9

3.6

0.4

30

17

17

6

97

8

–

–

spray. Yield differences between the carnea weeds, when used as green manure treatment with 60 kg N/ha + 2% urea at 10 t/ha, provide supplementary 40 kg solution spray and that with 60 kg N/ha N/ha and increase rice grain yield. They + Eichhornia inoculum spray were insig- do not proliferate in the field during suc- nificant. That indicates a spraying of ceeding seasons, however, if the leaves Eichhornia inoculum is as effective as 3 are properly incorporated before rice is sprayings of 2% urea. E. crassipes and I. planted.

A study of 225 randomly selected 1981. farmers was conducted in Haringhata Multiple regression analysis revealed block, West Bengal, India. to determine that NPK levels used explained 73% of the relationship between levels of fertil- the variation in boro (dry season-winter izer usage and rice yields during differ- rice) yields, 40% variation in aus (Sep- ent seasons. Data for the preceding year tember, pre wet-season) yields, and 7% were collected from January to March variation in aman (wet season) yields.

IRRN 8:2 (April 1983) 19

Treatment results indicate azolla is an efficient substitute for N fertilizer in sandy soil where there is likely to be ver- tical and lateral leaching. This may be because azolla releases N slowly and steadily, thereby limiting N losses.

Effect of phosphorus fertilizer placement on root and shoot growth of wetland rice

A. A. Jakhro, research officer, Institute of Agriculture, Timbang Menggaris, Sabah, East Malaysia

A pot experiment was conducted to determine the effect of phosphorus (P) placement on root and shoot growth of wetland rice. P was applied to varieties IR42 and MR7 at 0 (surface application), 5, 10, and 15 cm soil depth in 6 replications. Pots were 35 cm in diameter and 45 cm deep. Ten kilograms of clay loam (pH 5.8, organic carbon 1.05%, 0.15% total N, 4 ppm available P, 0.26 meq exchangeable K/100 g, and 17.4 meq CEC/100 g) were added to each pot. Soil was puddled

Computed F -ratios were significant at 1% in each case. N, K, and P levels used contributed positively and significantly

Azolla — a supplemental nitrogen source for flooded rice culture

Y. Yogeswara Rao, G. Rama Subba Reddy, and K. Ramaseshaiah, Agricultu- ral Research Institute, Rajendranagar, Hyderabad, India

In an experiment to evaluate the relative advantage of using Azolla pinnata as a supplemental source of nitrogen in combination with fertilizer urea, azolla was added at 5, 10, and 15 t/ha to plots fertilized with urea (see table). The experiment was conducted in a randomized block design with four replications at Rajendranagar during 1979-80 kharif. A uniform basal dose of 26 kg P/ha and 30 kg K/ha was applied to all plots. The variety used was Tellahamsa. The nitrogen content of azolla on wet weight basis was 0.25%.

Differences in grain and straw yields were significant among treatments. The

Azolla as a substitute for nitrogen fertilizer in rice

T. I. Mathewkutty and C. Sreedharan, Kerala Agricultural University, Vellanikkara, S. India

A study to assess the potential value of azolla as a substitute for nitrogen fertilizer in rice in sandy soils was made during 1981 kharif in Kerala.

Fourteen treatment groups in a randomized block design with 3 replications included azolla incorporation at 10 t/ha, azolla inoculation at 1 t/ha, a combination of incorporation and inoculation, and a combination of azolla inoculation and nitrogen fertilizer at 30 kg/ha, applied at basal, active tillering, and panicle initiation stages.

Grain yield (2.9 t/ha) and straw yield (3.0 t/ha) were greatest with basal incorporation of azolla combined with dual culturing and in situ incorporation at active tillering stage and 30 kg N/ha applied at panicle initiation. Several other treatments, including a treatment that

20 IRRN 8:2 (April 1983)

to boro rice yield and were ranked first, Of the plant nutrients, N and P levels second, and third, respectively, in used contributed positively and signifi- importance. cantly to aman yield.

Yield of rice as influenced by azolla and inorganic nitrogen fertilization. Rajendranagar, Hyderabad, India.

Grain Straw

Treatment Yield (t/ha)

Increase (%) over yield in Yield

(t/ha) control control

Increase (%) over yield in

100 kg N/ha 87.5 kg N + 5 t azolla/ha 62.5 kg N + 15 t azolla/ha 75 kg N/ha 37.5 kg N + 15 t azolIa/ha 50 kg N/ha 25.0 kg N + 10 t azolla/ha 12.5 kg N + 5 t azolla/ha 25 kg N/ha

Control C.D. at 5%

3.7 3.6 3.4 3.0 3.0 2.8 2.7 2.2 2.0 1.3 0.6

highest grain yield — 3.7 t/ha — was obtained with 100 kg N/ha supplied through urea. It was significantly higher than that of the other treatments but on par with those obtained with 87.5 kg N + 15 t azolla/ha and 62.5 kg N/ha + 15 t azolla/ha. Similarly the grain yield with 37.5

185 177 162 131 131 115 108 69 54 – –

4.3 4.1 3.9 3.4 3.4 3.2 3.1 2.9 2.8 1.8 0.4

139 128 117

89 89 78 72 61 56 – –

kg N + 15 t azolla/ha was equal to that with 75 kg N/ha applied through urea. Differences among the other treatments were nonsignificant. In general the grain and straw yields were low because of late planting.

Grain and straw yield with azolla incorporation, Kerala, India, 1981.

Treatment a Yield (t/ha)

Basal Active Panicle Grain Straw tillering initiation

FN FN FN 2.2 2.6 AI FN FN FN+DC FN+DC FN+DC FN+DC FN+DC AI+DC AI+DC AI+DC AI+DC AI+DC

FN FN AI FN FN AI Aii FN FN Aii – FN

FN

FN – FN

Aii FN FN Aii

– – –

–

– –

2.6 2.9 2.8 2.9 2.4 2.8 2.7 2.8 2.4 2.8 2.5 3.0 2.3 3.0 2.4 3.0 2.7 3.1 2.6 2.9 2.6 2.8 2.9 3.0 2.7 3.1

CD (0.05) 0.38 N.S.

a FN = 30 kg N/ha, AI = azolla incorporation (10 t/ha), Aii = azolla in situ incorporation

@1 t/ha). (dual culture), DC = dual culture (inoculation

received no N fertilizer, had similar yields. The treatment that received 90 kg N/ha in 3 equal splits recorded the lowest grain yield (2.2 t/ha) (see table).

and 22 kg P/ha (triple superphosphate) was applied at 4 depths. Urea (200 kg N/ha) and muriate of potash (25 kg K/ha) were broadcast. Remaining N was topdressed at panicle initiation. Three replications were harvested at panicle initiation to record root and shoot dry weight and N, P, and K uptake. Grain yield was recorded for the remaining three replications.

Root and shoot dry weight and grain yield significantly increased for both varieties at 5-cm placement depth. Placing P at 10 and 15 cm decreased dry weights and grain yield (see table).

The linear relationship of root dry weight and dry yield had a highly significant correlation coefficient of 0.980 for both IR42 and MR7, indicating that placing P at the proper root zone en- hanced root growth and increased grain yield. N, P, and K uptake was greater at 0 and 5 cm placement depths than at 10 and 15 cm, indicating that nutrients are utilized most effectively by plant roots when P is placed in their immediate vici- nity (see figure).

Effect of P placement depths on root and shoot dry weight at panicle initiation and yield of wetland rice, a Sabah, East Malaysia.

IR42 MR7 Placement

depth (cm)

Root Shoot Grain Root Shoot Grain dry wt dry wt yield dry wt dry wt yield (g/pot) (g/pot) (g/pot) (g/pot) (g/pot) (g/pot)

0 3.7 b 22.85 b 155.6 b 3.6 b 27.41 b 154.5 b 5 4.3 a 25.77 a 165.8 a 4.4 a 30.32 a 166.0 a

10 3.5 b 21.30 c 153.1 c 3.5 b 24.3 c 152.8 c 15 3.2 bc 20.70 c 150.2 d 3.1 bc 24.10 c 150.8 d

a Means followed by the same letter are not significantly different at 0.05 level.

Response of prerelease rice cultures to nitrogen in light-textured soil

A. P. Vishwanath, research assistant, Y. S. Veeraraja Urs, junior agronomist, and M. A. Singlachar, rice agronomist, University of Agricultural Sciences, Regional Research Station, V. C. Farm, Mandya, Karnataka 571405, India

A field trial during 1980 kharif (wet season) studied the response to nitrogen levels of four prerelease rices (Table 1) on a red sandy loam with low organic matter and phosphorus, moderate potash, and pH of 6.1. IR20 was the check variety. The treatments were replicated four times in a split-plot design with variety on the main plots and nitrogen levels on the subplots. A basal application of 22 kg P and 42 kg K per hectare was given. Nitrogen was applied 50% at transplanting, 25% at 25 days after transplanting (DT), and 25% at 45 DT.

IET2490 and IET2730 responded significantly up to 120 kg N/ha; KMP39 response leveled off beyond 80 kg N/ha (Table 2). All cultures except Mandya Vani were superior to IR20.

Changes in nutrient uptake by wetland rice at different depths of phosphorus placement at panicle initiation, Sabah, East Malaysia.

Table 1. Characteristics of rices tested in Mandya, India.

Duration 1,000- grain wt

(g) Culture Cross

(days)

Mandya Vani IR8/CR1014 IR20 IR262/TKM6 KMP39 Jaya/W1263 IET2730 IR8/Annapurna IET2490 IR8/NP130

128 131 140 141 143

17 19 20 32 30

Table 2. Response of prerelease rice cultures to nitrogen in Mandya, India.

Nitrogen Grain yield (t/ha)

(kg/ha) Mandya IET2490 ET2730 KMP39 IR20

0 2.4 3.0 3.0 3.2 2.4 40 3.2 4.1 4.0 3.9 3.7 80 3.7 4.8 4.8 4.2 4.1

120 3.8 5.2 5.1 4.4 4.5 160 3.6 4.8 5.0 4.5 4.6

Vani

CD (0.05) Varieties: 0.36 Nitrogen: 0.33 Interaction: NS Cv (%) 11

Methods of zinc application to rice on Zinc (Zn) deficiency is a widespread sodic soil nutritional disorder of rice, particularly

in sodic soils under reclamation. A field U. S. Sudana and P. N. Takkar, Soils experiment to correct the problem was Department, Punjab Agricultural Univer- carried out on Ghabdan loam soil (salic sity, Ludhiana 141004, India Natraqualf) in Sangrur district of Punjab.

IRRN 8:2 (April 1983) 21

The soil at the site had pH 10.3, 0.08% organic carbon, 1.25% calcium carbonate, 80.4% exchangeable sodium, and 0.52 ppm available Zn. The treatments are in the table.

Before the experiment, 50% of the gypsum requirement was mixed in the 15 cm soil layer of all the plots. Thirty- day-old PR106 rice seedlings were transplanted to submerged soils in all plots and fertilized with 120 kg N/ha as urea and 26 kg P/ha as superphosphate.

Rice plants grew poorly in control plots and exhibited typical Zn deficiency symptoms. Zinc application, irrespective of method, caused significant increase in grain yield and increased Zn content of 40-day-old leaves, straw, and grain (see table). Soil application of ZnSO 4 before transplanting produced maximum grain yield (140% over control). Topdressing ZnSO 4 7 or 15 days after transplanting produced similar grain yield. Foliar spray of 1% or 2% ZnSO 4 solution increased

Effect of methods of zinc application on zinc content and rice grain yield. a

Treatment Grain yield b Increase (%) Zinc content (ppm)

(t/ha) Over control Leaf c Straw Grain

Root dip 2% ZnO suspension 4% ZnO suspension

Foliar sprays (3) 1% ZnSO 4 solution 2% ZnSO 4 solution

Root dip + foliar sprays (2) 2% ZnO suspension + 1% ZnSO 4 4% ZnO suspension + 1% ZnSO 4

Soil application of 50 kg ZnSO 4 /ha Before transplanting 7 days after transplanting 15 days after transplanting

Control

CD at 5%

3.2 3.3

2.5 2.8

3.9 4.1

4.3 4.2 4.0

1.8

0.4

74 81

38 55

115 1 26

140 133 123 –

–

15.1 16.3 9.9 15.7 17.1 10.4

16.2 14.2 9.4 16.7 15.1 9.7

18.6 17.6 10.6 19.8 18.4 11.0

17.6 18.8 12.2 17.1 19.3 11.9 16.2 18.5 11.2

10.8 11.7 8.9

0.9 0.9 1.0

a Av of 3 replications. b Oven-dry basis. c Forty-day-old.

yield significantly over the control, but a 4% ZnO suspension supplemented with was inferior to all other methods of zinc foliar sprays of 1% ZnSO 4 solution gave application. Dipping rice seedling roots in yields similar to ZnSO 4 application.

Environment and its influence Low water temperature and sterility in rice

Y. S. Ham, J. H. Lee, B. S. Vergara, R. M. Visperas, and S. Y. Kim

Rice plants are most sensitive to low temperature during meiosis or when the auricle distance between the flag leaf and the leaf immediately below is zero. Low temperature at this stage usually causes high spikelet sterility. In some rice growing areas, fields are flooded above the growing point of plants to protect them from cold air temperature at night. Irrigation water is warmer than ambient air and protects the growing point from cold night air.

In some rice growing areas, however, irrigation water is cooler than the air temperature. Tests in Chuncheon, Korea, showed that 17°C water temperature can cause 100% sterility (see figure). How- ever, water depth and plant height or position of the growing point during

Sterility of rice cultivars treated with low water temperature at different stages of panicle development.

22 IRRN 8:2 (April 1983)

meiosis were important factors. Tall (Cheoulwon 21), a short variety, was Results also showed that plants are plants, like Leng Kwang, escaped cold seriously damaged, even in shallow water. most sensitive to low temperature when water injury because panicle height from In Chuncheon, where the water is colder auricle distance is – 15 or – 10 cm. soil surface was greater. Seulak than air, shallow water is preferable.

Announcements Seed Technology Course seed industries, particularly in developing the organization and development of na-

The University of Edinburgh is offering a It covers all aspects of seed technology For further information write: The 1-year graduate course leading to a including production, processing, storage, Course Director, Seed Technology, the diploma or MSc in seed technology. The marketing, quality control, legislation and Edinburgh School of Agriculture, West course is intended to train personnel for management with emphasis on major Mains Road, Edinburgh, EH 9 3JG, Scot- senior technical and managerial posts in cereal crops. Special attention is given to land, UK.

countries. tional seed programs.

Khan named Fellow

Dr. Amir U. Khan, Agricultural Engineer- ing Department, IRRI, has been named a Fellow of the Pakistan Society of Agri- cultural Engineers in recognition of his contribution to agricultural engineering in Pakistan and of his work with the variety.

New IRRI publications Biology and management of riceland rats

New IRRI publications available for pur- Field problems of tropical rice (rev. ed.) chase from the Information Services Parentage of IRRI crosses IR1-IR30,000 Department, Division C, IRRI, P.O. Box Rice area by type of culture: South, 933, Manila, Philippines are: Southeast Asia and East Asia

Agroclimatic and dry-season maps of postharvest technology

in Southeast Asia

Technical handhook for the paddy rice

South, Southeast, and East Asia

Brown planthopper publications

Two reports discussing brown planthop- es of BPH and the stage of development graphy and geographical index of litera- per (BPH) Nilaparvata lugens are availa- of the rice crop, 22 p., 9.40 – concludes ture on BPH, 163 p., £10.50 – compiled ble from the Centre for Overseas Pest that periods of rice harvest can be used in 1979, identifies country and locality Research, College House, Wrights Lane, to predict the presence of macropterous where research was conducted, the nature London W85SJ, UK. emigrants in areas where no BPH surveys of the work, and the source of BPH used

sible correlation between light trap catch- Miscellaneous Report No. 58 -- Biblio-

Miscellaneous Report No. 57 – A pos- occur. in laboratory experiments.

IRRN 8:2 (April 1983) 23

Documents

International Rice Research Newsletter Vol.8 No.2