OVERALL PROGRESS

Genetic evaluation and utilization Rice germ plasm survey in Sambalpur, Orissa, India

J. K. Roy, Central Rice Research Institute, Cuttack, India

A program of the Central Rice Research Institute, Cuttack, to collect rice germ plasm gives priority to upland and tribal areas of India where the gene erosion is relatively rapid. In Orissa, early types were surveyed and collected from Sambalpur and parts of two adjoining districts during kharif 1976.

and Bargarh, with assured irrigation from Hirakud reservoir, grow only a few improved and high yielding varieties. T. 141 and Akulu, two improved local indicas, occupied about 70% of the rice area. Among the high yielding varieties, the gall midge-resistant Shakti (CR.93-4-2) in the medium lands and Jagannath in low lands were more popular. In the irrigated Dungeripalli block of the adjoining

Farmers in irrigated blocks of Attabira

Bolangir district, improved varieties also occupied a major rice area. T.141 and T.192 (locally called 192) were most popular. Farmers of the irrigated zones prefer to grow only a few improved varieties in kharif; in rabi, they grow mostly high yielding varieties.

In nonirrigated tracts, the genetic diversity was considerable. In Jharsuguda and Rairakhol subdivisions of Sambalpur district and in the adjoining parts of Dhenkanal, most farmers grow a number of local varieties, mostly early maturing. Fifteen to 20 varieties could be collected from any single village. The early varieties Guda Saria, Hari Sankar, Jhilli, and Kalakartika in the Jharsuguda tract, and Punei in the Rairakhol tract, were most common in uplands. During kharif 1976, 70 varieties from Sambalpur and about 800 varieties from all parts of lndia were added to the genetic stocks of the Institute.

GENETIC EVALUATION & UTILIZATION

Disease resistance Two possible new sources of resistance to resistances from a single source, TKM 6. bacterial leaf blight of rice In light of the reported variability in the

J. S. Nanda, R. C. Chaudhary, H. Singh, virulence of X. oryzae, the use of diverse

B. N. Singh, and J. P. Singh, Department sources of resistance becomes obligatory.

of Plant Breeding, G. B. Pant University of Agriculture and Technology, Pantnagar 263145, India

At Pantnagar, India, in 1973, 93 distinct types were established from a boro rice collection (made in 1972) from

All the released rice varieties that are previously unexplored areas of eastern resistant to bacterial leaf blight caused by Uttar Pradesh. They were screened for Xanthomonas oryzae derive their resistance to bacterial leaf blight. During

Reactions of boro varieties to bacterial leaf blight, Pantnagar, India, 1973–76.

Varieties (no.)

Year Resistant Moderately resistant Susceptible Total (0-3) (5) (7-9)

1973 1 7 84 92 1974 2 7 84 93 1975 3 11 79 93 1976 2 0 91 93

2 IRRN 2:1 (February 1977)

the last 4 years the screening was repeated under field conditions with high disease pressure. Two cultivars have given resistant reactions consistently. They have been named UPRB 30 and UPRB 31. During kharif 1976 their reactions were confirmed by pinprick and clip inoculation methods. Both cultivars are tall (130 cm); high tillering (15 tillers); with pigmented basal leaf sheaths and apiculi; long, narrow leaves; and medium-bold grains. Both mature in 130 days. UPRB 30 is awned; UPRB 31 is awnless. UPRB 31 is also resistant to blast disease. Studies of the allelic relationship of these new sources with the reported ones are in progress. UPRB 30 and UPRB 31 are being utilized in our breeding program.

Reaction of certain rice varieties to stem rot diseases

S. Srinivasan, S. Kannaiyan, P. Chinnasamy, and R. Venkataraman, Plant Pathology Laboratory, Paddy Experiment Station, Aduthurai-612101, Tamilnadu, lndia

A field trial was conducted in 1975 kuruvai (June–October) to investigate the reaction of certain varieties to stem rot of rice incited by Sclerotium oryzae Catt. The natural occurrence of the disease was assessed during the grain maturity stage of the crop. The grain yield for the varieties was recorded. Of the 32 cultivars tested, 13 were relatively resistant compared with Jayanthi, which is representative of the susceptible group (see table).

Varietal reaction of certain rices to stem rot disease. India, 1975.

Disease Cultivar incidence Yield

(t/ha) (%)

IR71 0.5 3.3 CR-137-41-15 2.3 5.7 CR-137-41-2 2.4 5.6 CR-HP.3 3.1 4.7 IR272 3.9 5.2 Shiranui 4.9 4.5 RP-260-288-1-1 5.0 4.3 DCA-31 5.1 7.1 RP-1B-31 6.4 5.9 CR-137-36-30 6.8 8.1 CR-141-4004-1-191 7.9 2.0 Cult. 8946 8.2 4.7 Malagkit sungsong 8.4 1.3 Jayanthi 56.6 2.9

Parentage of 400 rice lines identified as resistant or tolerant to the brown planthopper and grown in an observational trial at Pattambi, India, 1976.

Parentage Lines (no.)

Bharathi/lR2071-625-2-1 103 Triveni/lR2061-461 75 Triveni/Mudgo 96 Triveni/lR1539 126

GENETIC EVALUATION & UTILIZATION

Insect resistance Mixing rice varieties to combat brown planthopper

P. Weerapat, W. Purivirojkul, and T. Chaturonrangsri, Rice Division, Department of Agriculture, Bangkok, Thailand

progenies in F 4 were tested under field conditions at Pattambi, Moncombu, and Mannuthy. These progenies were also tested at the seedling stage under greenhouse conditions at the All India Coordinated Rice Improvement Program, Hyderabad, and 400 selections were identified as tolerant or resistant to brown planthopper on the basis of both field and greenhouse observations. Those 400 lines (see table) were grown in an

Various mixtures of two rice varieties – observational trial during the first crop one resistant to brown planthopper season of 1976. (BPH) damage and one susceptible – were grown to study the relationship between the mixtures and damage by insects. RD7, a susceptible variety, and RD9, which carries the Bph 1 resistance gene, were used. Both are high yielding, semidwarf types; RD9 matures slightly earlier.

Mixed seeds were germinated in petri dishes and planted in wooden flats; at the two-leaf stage, heavy populations of first-instar BPH were released to infest the seedlings for 10 days. The RD7 population was 100% damaged; the RD9 population was undamaged. In a mixture of 50% RD7 and 50% RD9, 82% of the plants were undamaged; in a mixture containing 66.7% RD9 plants, 72% were undamaged. Random combinations of environmental variables may have affected results, but the data suggest that introducing at least a 50% portion of resistant plants into a susceptible population may reduce damage to levels lower than that expected on the basis of the ratios of the varieties.

Breeding for resistance to brown planthopper and grassy stunt in Kerala, India

K. I. James, rice breeder, and P. A. Varkey, junior rice breeder, All India Coordinated Rice Improvement Program, Rice Research Station, Pattambi, India

Breeding for resistance to the brown planthopper and the associated grassy stunt virus has been under way at the Rice Research Station, Pattambi, Kerala, India, since 1974. During 1975, bulked

A crossing program has been undertaken with donors for brown planthopper resistance that are thought to be most appropriate for the Kerala region. Fifty-five crosses involving the varieties PTB 33, PTB 18, PTB 21, and others as sources of resistance were accomplished during 1975.

GENETIC EVALUATION & UTILIZATION

Deep water Screening for kneeing ability

B. S. Vergara, R. Visperas, and J. Peralta, International Rice Research Institute; E. Shuwisitkul, S. Karin, and S. Sophonsakulkaew, Rice Division, Department of Agriculture and Cooperatives, G.P.O. Box 2453, Bangkok, Thailand

Rice plants usually lodge after the internodes have elongated and floodwaters have receded. Deep-water varieties must have kneeing ability to keep the first three leaves above the water level, preventing leaf decay and providing better leaf arrangement. Kneeing also bears the panicle above the reach of fishes.

A system for scoring the kneeing ability of deep-water rice cultivars.

To test for kneeing ability, use a puddled and leveled field, and rice plants at least 60 days old. Dig carefully around the base of each rice plant and pull out the plant gently. Use four plants for each variety. Lay each plant horizontally on the puddled field. Label. Randomize the varieties to be tested. Maintain water depth at 2 cm. The plants tend to move around or roll if the water is too deep. On the eighth day, score for kneeing ability (see figure).

IRRN 2:1 (February 1977) 3

GENETIC EVALUATION & UTILIZATION

Temperature tolerance Rice response to extreme temperatures in Saudi Arabia from Australia, but not that of japonicas

W. L. Chang, H. P. Su, and F. H. Lin, Chinese Rice Mission, Hofuf Agricultural Research Centre, Saudi Arabia

Winter and summer 1976 crops of 36 rices, including cultivars from Africa, Australia, India, IRRI, Japan, Korea, Saudi Arabia, and Taiwan, were observed for their reactions to extremely low and high temperatures (Table 1) at Al-Hassa Oasis, the main rice-growing area in Saudi Arabia.

Low spring temperatures affected the early growth of winter rice, particularly that of indicas, although most recovered eventually. Decreasing fall temperatures appeared not to harm the ripening summer crop. High temperatures during later growing stages of the winter crop damaged only the grain filling of traditional tropical rices and YR lines

from Japan and Taiwan. Vegetative growth of the summer crop, especially of japonicas, was severely stunted by intense heat and strong sunlight during early growth. Heat stress was also reflected in the low fertility of japonica rices; indicas ripened normally (Table 2). Grain yields (expressed in panicle weight per plant) of the summer crop, except of the tropical rices, were considerably lower than those of the winter crop. The findings suggest that high yielding semidwarf indica and japonica rices can be grown successfully as winter crops in Al-Hassa. For the hot summer crop, the modern rices are apparently not as well adapted as the traditional rices. Marked differences in varietal responses, however, suggest that improved varieties better suited to local conditions could be selected.

Table 1. Average temperature during several growth stages of winter and summer crops, AI-Hassa, Saudi Arabia, 1976.

Temperature (°C)

Growth stage Winter crops Summer crops

Min. Max. Min. Max.

Transplanting 11.5 31.4 17.8 46.8

Heading-ripening 16.5–16.4 42.8–46.3 15.9–14.7 45.0–43.2 Average (10 a.m.) 31.4 34.6 38.5 42.3

Table 2. Performance of winter (W) and summer (S) rice crops, AI-Hassa, Saudi Arabia, 1976.

Plant type Fertility (%) Panicle weight (g/plant)

W S W S

Indica Semidwarf 86.8 87.5 Tropical 30.4 87.3 YR Line 22.7 35.8 Mean 46.6 70.2

55.8 36.2 26.8 46.8 18.6 12.1 33.7 31.7

Japonica Japanese 80.8 10.4 44.3 Ponlai

3.0

Mean 85.9 24.1 52.9 6.6 90.9 37.7 61.5 10.1

4 IRRN 2:1 (February 1977)

GENETIC EVALUATlON & UTILIZATION

Adverse soils Varietal tolerance of rice to iron toxicity in Liberia

S. S. Virmani, rice breeder, International Institute of Tropical Agriculture; Central Agricultural Experiment Station, Ministry of Agriculture, Suakoko, Monrovia, Liberia

Iron toxicity and associated nutrient disorders of rice occur widely in swamp valleys newly developed for rice in Liberia and in similar regions in other West African countries. Yield reductions of 10 to 90% have been recorded in the affected areas. Symptoms vary, depending on the variety and the type of imbalance. Bronzing of the leaves starting at the tips is characteristic, but oranging or yellowing of leaves may occur; stunting may occur, with scanty root production and spikelet sterility.

In 3 years, 1,400 lines have been screened at the Central Agricultural Experiment Station, Suakoko, in an iron-toxic swamp (pH less than 5, organic matter 5%) that is irrigated by seepage water containing a high level of soluble iron. Most lines have been eliminated from further consideration. Gissi 27, a photoperiod-sensitive local variety, has been found to be consistently tolerant. At maximum tillering its leaves contain 560 ppm iron, compared with 1,650 and 1,720 ppm contained in leaves of the susceptible lines IR269-26-3-3-3 and IR589-54-2. Several lines derived from IR2031, IR2053, IR2070, IR2071, lR2153, and IR2688 have been observed to be tolerant. They involve iron-toxicity- tolerant lines (IR20, IR1416-131-5, and CR94-13) in their parentage. Tolerance appears to be heritable. Some lines from Sri Lanka (Dewarederri, BW191, BW196, BG35-2), Indonesia (B 1896-29-4-3-1, B 4596-Pn-132-3-5, B 459-Pn-132-8-1, B 462-CPn-1-3), and Malaysia (2526, Improved Mahsuri) are also tolerant. Screening and crossing of more germ plasm from those entries should help to develop improved iron-toxicity-tolerant varieties. Several dry-land varieties –

LAC 23 (Liberia), Azmil 26 (Philippines), Line 2526, introduced from Malaysia and long slender grains; it is insensitive to TOS 4020, TOS 3814 (IITA), and derived from the cross Siam 25 x day length and moderately susceptible to IR1476-F5B-13, IR2989-13, and Malinja 3 , is the most promising of the blast, leaf scald, and brown spot diseases IR2992-27 (IRRI) — also have shown tolerant cultivars. It is of intermediate in Liberia. It is being tested in minikit tolerance to iron toxicity. height (120 cm), tillers well, and has trials in farmers’ fields in Liberia.

Pest management and control DISEASES

“Empty-head” — a serious rice problem in Taiwan

Chao-yen Hsieh, Plant Industry Division, Joint Commission on Rural Reconstruction, Taiwan

“Empty-head’’ was severe in the second rice crop of 1976 in southern Taiwan, and occurred sporadically in central and northern areas. About 17,000 ha were affected in some major rice-growing areas. The characteristic symptom is abnormally erect panicles with partially filled or completely empty grains in mature plants. Brown or dark-brown spots appear on panicles and grains and, in severe cases, cover most or all of the surface of some grains. The uppermost leaf sheaths of affected plants turn partially or completely brown; upper internodes of stems enclosed by the uppermost leaf sheath are distorted and have a zigzag appearance. Brown stripes or blotches usually appear on the upper portion of the stem.

The sporadic occurrence of “empty- head” has been noticed since 1968 in the Tainan area. Evidence seems to associate it with the rice tarsonemid mite Steneotarsonemus madecassus Gutierrez and the sheath-rot fungus Acrocylindrium oryzae Sawada, although the frequent use of organoarsenic compounds, leading to a high arsenic content in the paddy soil, is not excluded as a possible cause. S. P. Y. Hsieh, National Chung Hsing University, recently isolated a large number of conidia of A. oryzae from the “empty- head” rice plants, and about 97% of the tarsonemid mites carried conidia.

Biological relationships between the mite and the sheath-rot fungus have not been investigated. At present, the mites

are regarded as a primary factor because large numbers were invariably detected inside spikelets, grains, and leaf sheaths. A research team of entomologists, plant pathologists, and pesticide specialists coordinated and supported by the Plant Industry Division, Joint Commission on Rural Reconstruction, currently has work under way at several research institutions and locations on the “empty-head” problem.

Seed transmission of bacterial leaf blight of rice and its treatment

R. A. Singh and M. H. S. Rao, Department of Plant Pathology, G.B. Pant University of Agriculture and Technology, Pantnagar-263145, India

Several treatments were tested to determine their relative efficacy in eradicating Xanthomonas oryzae (Uyeda and Ishiyama) Dowson from infected rice seed.

Seeds collected from a crop severely infected with bacterial leaf blight were treated with hot water, Brestanol, Streptocycline + Ceresan, Agrimycin + Ceresan, and both dry and slurried Streptocycline, HPMTS, RH 893, Vitavax, and Agricultural Terramycin 17. Hot water, HPMTS, and Brestanol seed treatments completely eradicated the pathogen from the infected seed. Brestanol seed treatment, besides being highly effective in eradicating the pathogen, also gave a higher percentage of germination. In general, slurry seed treatments were more effective than dry seed treatments using the same chemicals. The systemicity of Brestanol and HPMTS was tested after seed treatment, and it was found that those chemicals are absorbed and translocated in the seedlings of treated seeds.

Bacterial blight of rice in Pakistan

T. W. Mew, The International Rice Research Institute; and Abdul Majiid, Rice Research Institute, Kala Shah Kaku, Pakistan

Bacterial blight of rice, caused by Xanthomonas oryzae (Uyeda and Ishiyama) Dowson, is one of the major diseases of the crop in Asia. However, it has not been reported from Pakistan. During a survey trip in October 1976, we observed the disease on some Basmati varieties grown at the Rice Research Institute, Kala Shah Kaku, Pakistan. Lesions appeared typically water soaked, with wavy margins and grayish white color on infected leaf blades. Lesion length as well as type suggested that the varieties were quite susceptible. Disease incidence in the field was relatively high. When infected leaves were examined microscopically, bacterial ooze streamed from cut edges of the lesions, although inoculations have not yet been made to confirm the pathogenicity.

In vitro effect of certain fungicides and antibiotics against the bacterial leaf blight pathogen

M. Deiveegasundaram, S. Kannaiyan, and N. N: Prasad, Microbiology Laboratory, Agriculture College, Annamalai University, Annamalainagar 608101, Tamilnadu

Thirteen fungicides and six antibiotics were tested for effectiveness against Xanthomonas oryzae (Uyeda and Ishiyama) Dowson, the pathogen of bacterial blight of rice. They were tested at 250, 500, and 1,000 ppm.

At all concentrations tried, the fungicides thiram, captan, Vitavax, and Difolatan inhibited the growth of X. oryzae. Among the antibiotics, Streptocycline and Chloroamphenicol at all concentrations arrested the growth of the pathogen.

IRRN 2:1 (February 1977) 5

Field efficacy of certain chemicals in the control of bacterial blight of rice in the Punjab

Nirmaljit Singh, Harnam Singh, and J. S. Chohan, Department of Plant Pathology, Punjab Agricultural University, Ludhiana, Punjab, India

Bacterial blight of rice caused by Xanthomonas oryzae (Uyeda and Ishiyama) Dowson is a major disease in the tropics. In a field trial during kharif 1976, seedlings of Jaya were inoculated with a virulent isolate of X. oryzae 3 wk after transplant. Chemicals were

sprayed four times at fortnightly intervals starting 72 hours after inoculation at the rate of 2 liters/plot. Observations for bacterial blight were recorded 10 days after the last spray (see table).

Less disease was recorded in plots sprayed with copper oxychloride and with Agrimycin-100 + copper sulfate than in the unsprayed check. Agrimycin- 100 alone and streptocycline showed little effect. There were no significant differences in yields with the various treatments. The yield of the inoculated control was 25.9% less than that of the uninoculated check.

(Shirai) Matsumoto. They were sprayed twice during the maximum tillering stage of the susceptible variety ADT-31. Compared with the untreated control, all the test fungicides minimized disease incidence. Benlate, Demosan, Hinosan, Kitazin, and Daconil were found to be highly effective. The treated plots also had significantly higher grain yield than the untreated control.

Root-lesion nematode damage in upland rice

Y. S. Rao and J. S. Prasad, Central Rice Research Institute, Cuttack – 753006,

Relative efficacy of various chemicals in controlling bacterial leaf blight of rice. Orissa, India

Treatment Concentration Disease

incidence a

(%) b

Yield (t/ha)

Agrimycin-100 200 ppm a.i. c 33.85 (31.0) 4.80 Streptocycline 200 ppm a.i. c 33.95 (31.2) Agrimycin-100 200 ppm a.i. c

+ 31.23 (26.9) Copper sulfate 100 ppm a.i. c

Copper oxychloride 0.2% (Commercial) 29.70 (24.6) Inoculated control

(water spray) 36.02 (34.6) Uninoculated control

a Average of six replications. b C.D. at 5% level = 4.21; C.D. at 1% level = 5.74. Figures in parentheses indicate percent disease

4.85

4.95

5.05

4.85 – – 6.55

index. Others are transformed values and C.D. applies to these only. c a.i. = active ingredients.

Antibiotics for control of sheath blight of Tetracycline, Kasumin, or rice oxytetracycline. All of the treatments S. Kannaiyan and N. N. Prasad, reduced the disease incidence; the Microbiology Laboratory, Agriculture antifungal antibiotic Aureofungin was College, Annamalai University, Annamalainagar-6089101, Tamilnadu, India recorded from the plots treated with it.

highly effective. Increased yield was also

Sheath blight of rice caused by Corticium sasakii (Shirai) Matsumoto is increasing in severity in certain parts of Tamilnadu because of the introduction of rice strains that are high yielding and responsive to heavy fertilization.

conducted during the kuruvai (June- September 1975) and the thaladi (October 1975 – January 1976). During its maximum tillering stage the susceptible rice variety ADT-31 was sprayed twice with a 1,000-ppm concentration of Agrimycin-500, Streptocycline, Blasticidin, Polyoxin, Aureofungin,

A field trial of eight antibiotics was

Observations indicate the potential of the polyphagous nematode Pratylenchus indicus as a pest of rice in uplands and in soils where crop rotations with susceptible cereal and fodder grass crops are adopted. In recent surveys on the Central Rice Research Institute farm, the prevalence of the nematode was observed. Direct-seeded rice showed patches of yellowing plants within 15 days of germination. In the following week, leaves wilted and dried up. Mortality was complete at 40 to 50 days after germination (see photograph).

lesions with necrotic cells in the cortex. All the stages of P. indicus were observed inside roots. The nematode population increased with plant age and peaked in October 1975 when the crops were heading. The symptoms at that stage were yellowing of leaves in patches, and

Roots of infested plants showed surface

partial earhead exsertion. Fungicidal control of sheath blight of rice

S. Kannaiyan and N. N. Prasad, Microbiology Laboratory, Agriculture College, Annamalai University, Annamalainagar-608101, Tamilnadu, India

The fungicides Benlate, Dexon Wet, Ceresan, Daconil, Dithane Z-78, Dithane D-14, Kitazin, Hinosan, N.F. 48, Brassicol, Brestan, El-273, thiram, and Demosan in 2% solutions were tested for the control of sheath blight of rice caused by Corticium sasakii

Mortality of nematode-infested upland rice at Cuttack, India, 4 to 50 days after germination.

6 IRRN 2:1 (February 1977)

India is beginning to associate surveillances of rice pests with control measures and research. Among several surveillance programs is a pilot program of the Directorate of Plant Protection, Quarantine, and Storage (DPPQS) to monitor rice, potatoes, sugarcane, and wheat from Central Surveillance Stations in 12 districts in 9 states. Each

station has a surveillance officer and six field reporters. Each field reporter collects data weekly from 20 fixed fields of the selected block in which he works with sampling equipment, meteorological equipment, and light traps. He also makes a weekly roving survey of a portion of the block. State governments use the surveillance information, along with economic threshold values supplied by the All India Coordinated Rice Improvement Project, to determine need for pest control measures and type of control needed. Sampling methods and

S. N. Banerjee and K. C. Mathur, Directorate of Plant Protection, Quarantine, and Storage, Faridabad - 121 001, India

Colony diameter (mm) of mycelial growth of H. oryzae 7 days after inoculation replicates).

Treatment

Monocrotophos 5 G MIPC 4 G Quinalphos 5 G A.C. 92, 100 Check

Colony diameter (mm) at insecticide doses of

1000 ppm 500 ppm 250 ppm 100 ppm 50 ppm

– – – – – – – – – – – – – 15.0 15.6 24.0 30.0

65.0 65.0 65.0 65.0 65.0

– 18.3 20.0

a

a (mean of three

8 mm.

Surveys of other rotation crops in rice soils under upland conditions showed the infestation of ragi, wheat, and sorghum in that order. Some grasses in and around

rice fields (Echinochloa colona, Cyperus sp., Alternanthera sessilis, Eragrostis pilosa, Eleusine aegyptica, and Cynodon dactylon) were found to be suitable

Some granular insecticides tested against rice brown spot disease

G. G. Mukherjee, Mycology Section, and S. C. Sen, Entomology Section, Rice Research Station, Chinsurah, Hooghly, West Bengal, India

To explore their potential for controlling brown spot disease of rice, monocrotophos 5 G, MIPC 4 G, quinalphos 5 G, and AC 92100 5 G, mixed with 20 ml potato-dextrose-agar, were bioassayed against the disease pathogen Helminthosporium oryzae Breda de Haan in vitro.

hosts for this nematode. In rice followed by the fodder grass crop Pennisetum pedicillatum, nematode infestation resulted in 12 to 17% yield loss. A preliminary survey of areas in Kerala, Gujarat, Orissa, West Bengal, and Assam confirmed the prevalence of P. indicus in association with rice culture.

The growth of H. oryzae was inhibited by all the granular formulations (see table) even at the lowest test dose. It was completely inhibited by monocrotophos and MIPC at the dose of 50 ppm, by quinalphos at 250 ppm, but by AC 92100 5 G only at 1,000 ppm. Granular formulations of the above insecticides may be useful in the control of rice brown spot disease. However, more detailed investigations are needed to prove their potential against H. oryzae in the field.

Pest management and control INSECTS

Rice surveillance in India

the type of information sought are being modified with experience. The process of station-establishment needs improvement, and states and farmers need to become better prepared to undertake control measures in large areas on short notice.

DPPOS also organizes roving surveys during kharif in Punjab, Uttar Pradesh, Bihar, Assam, Orissa, Madhya Pradesh, and West Bengal, chiefly to monitor populations of the tungro vector Nephotettix virescens. DPPQS processes the data and issues weekly bulletins. When N. virescens counts reach two or three insects per rice hill, state govern- ments are advised to begin control measures. Control alerts are also provided for other pests and diseases. It is planned to extend these roving surveys together areas and other rice seasons.

Following an epidemic in Kerala, DPPQS and the State have also organized a special surveillance program for the brown planthopper. In many cases it now is possible to provide timely warning of upcoming pest problems, although not always possible to institute timely control measures.

Proposed integrated studies of pest control problems

Renuka Sengupta and J. J. Ghosh, Department of Biochemistry, University College of Science, Calcutta - 19, India

A study is planned to evolve an integrated picture of the interactions among the pests, pesticides, and nontarget organisms involved in rice culture.

The first part of the study will investigate the action of different organochlorine, organophosphorous, and carbamate pesticides on such nontarget organisms as goats, sheep, rats, frogs, fish, and invertebrates (e.g. mollusks and earthworms). The second part will emphasize the mode of action of the pesticides in important rice pests (e.g. Tryporyza sp. and Chilo sp.) and the pests' relative sensitivity to different pesticides. Changes in soil chemistry also will be studied.

Several biochemical parameters of target and nontarget organisms, such as

IRRN 2:1 (February 1977) 7

acetylcholinesterase, cholinesterase, and adenosine triphosphatases (both Mg ++ and Na + -K + ATPases) in brain, blood, and other tissues are study targets. The effect

Seed mats used in screening for gall midge resistance

G. van Vreden, entomologist, Central Research Institute for Agriculture, Bogor, Indonesia

In Indonesia we have developed and applied three methods for screening rice varieties for gall midge resistance: (a) open field screening, (b) continuous screening using colonized midges in the greenhouse, (c) testing inside easy-to- assemble screenhouses in the field. For (c), we started sowing 2 or 3 weeks before an expected peak in insect emergence. Midges were collected with mouth aspirators and released on miniplots in the screenhouses. The method was satisfactory but laborious because the seeds had to be individually sown 2–3 cm apart, 20 seeds/row for each variety. We developed a method for preparing seed mats in advance.

of pesticides on rice plants, particularly on vegetative growth and on the incidence and varieties of insect infestation, will be investigated.

Sowing distances are marked with ink on a sheet of paper, which is then covered by a transparent sheet of plastic, followed by paper tissue. The tissue is brushed with a thin starch solution to make it sticky and transparent. A cardboard strip on which varieties are identified by number is glued to the left side. Seeds are placed one by one on the marked spots. A second tissue is placed on top and gently pressed down with a brush. The sheets are picked up with the plastic underneath them and placed in the sun or in an airconditioned room to dry. The mats are sown on wet soil. Labels are placed beside the numbers on the sheets.

The method provides quick and accurate sowing, reduces the chance of sowing errors in sequence of varieties, prevents moving and loss of seeds when wetted carefully, and makes it easy to sow at distant sites with little instruction.

A new mite pest of rice in India

Y. S. Rao and P. K. Das, Central Rice Research Institute, Cuttack-753006, Orissa, India

Spider mites of the genera Oligonychus and Paratetronychus have previously been reported causing foliage damage to rice in India. During November 1975 plants were observed to have poorly exserted earheads and necrotic leaf sheaths, which were associated with feeding by mites. All mite stages were present between the stem and leaf sheath. Affected glumes had brownish to black lemmata and paleae and shriveled ovaries. The mite has been identified as Steneotorsonemus spinki Smiley: Tarsonemidal by R. L. Smiley, USDA, Beltsville, Maryland, USA, who says it has been previously collected from rice in Kenya and Taiwan. Panicle deformation has previously been attributed to S. nodecossas in Madagascar by V. H. Hai in 1968.

determine the nature of damage due to S. spinki.

We are continuing research to

Integrated control of Chilo suppressalis in Iran

P. Mostowfi, Plant Pests and Diseases Research Laboratory, Shasawar, Iran

Since 1972, when C. suppressalis was first collected in rice fields in Northern Iran, we have used cultural controls (plowing and flooding fields, removing stubble and host plant weeds, growing short-duration varieties) and selective insecticides against the pest. Results have been good.

In studying biological control of the pest, we have found three parasites and a disease of the insect:

1. Trichogramma evanenscens (egg

2. Apanteles sp. (larval parasite) 3. Andralus spinidems (larval parasite) 4. Beauveria bassiana (larval disease)

parasite)

The research is incomplete.

Seed mats are prepared in advance of a test in Indonesia for varietal resistance to gall midge.

8 IRRN 2:1 (February 1977)

Insecticidal sprays in alternate strips protect spider predators in paddy

U. S. Misra, senior entomologist, Operational Research Project on Integrated Control of Insect Pests of Paddy, Jawaharlal Nehru Krishni Vishwa Vidyalaya, Campus Agriculture College, Raipur, Madhya Pradesh, India

Significantly more spider webs were found on rice varieties RP 9-4 (gall midge-resistant) and Jaya (susceptible)

Treatment Spider webs (no./plot)

RP 9-4 Jaya Mean

Maximum protection c 6.25 8.0 7.13 Supervised control 10.0 10.75 10.38 Supervised control with strip spray e 22.75 18.75 20.75 Control (no treatment) 17.75 20.75 19.25

d

when insecticides were applied in alternate strips than when two other insecticide treatments were used (see table). Yield also was slightly higher than with no treatment, or with “supervised control” using blanket spray on Jaya. The unsprayed strips probably provided protected areas from which the spiders migrated to the rest of the plot after the toxic effects of the insecticides had disappeared.

Insecticide treatments and number of spider webs/plot a,b

Using carbofuran against the rice tungro virus vector in India

a C.D. at 5% for treatments: 4.96 webs/plot. b 75 days after transplanting (DT) c Seedling root dip in 0.02% carbofuran for 12-14 h before planting; cytrolane granules at 1.0 kg

d Cytrolane granules at 1.0 kg a.i./ha if on the average there was 1 silver shoot/sq m (true only in

a.i./ha per application 20 and 40 DT; and methyl parathion spray (0.05%) 30 and 60 DT.

Jaya at 30 DT); and 0.05% methyl parathion spray when hopper population was 10 to 25 insects/hill.

e Like d, but treated strips alternated with untreated strips. Each plot had 4 strips containing 12 rows per strip.

G. Mohana Rao, V. D. Shukla, and A. Anjaneyulu, Central Rice Research Institute, Cuttack-753006, India

Seven granular and six emulsion- concentrate systemic insecticides commonly manufactured in India were initially tested for their persistence against the rice tungro virus vector Nephotettix virescens. Carbofuran, fensulfothion, and phorate were found to be most effective, on the basis of residual activity. Their efficacy in preventing virus infection was tested by artificial inoculation in a net house and in field trials. In artificial inoculation tests, carbofuran at 1 kg a.i./ha prevented the infection to a great extent in TNl, up to 18 days after application; the other two failed to do so. In field trials, carbofuran at 2 kg a.i./ha, broadcast at 15-day intervals, most efficiently restricted the spread of tungro virus infection under severe disease pressure. The virus infection, however, was high at 1 kg a.i./ha. The control and the plots treated with phorate and fensulfothion were 100% infected.

Removal of silver shoots reduces is highly susceptible to gall-midge

gall-midge infestation infestation. In moderately susceptible

U. S. Misra, rice entomologist, Central initial gall-midge infestation was very effective in preventing and restricting Rice Research Station, Raipur, M.P., India

The removal of silver shoots reduced The removal of silver shoots can be conducted on the mechanism of virus gall-midge infestation and brought about integrated with other control methods by infection in plants treated with different significantly higher yield in Jaya, a farmers who grow high yielding varieties insecticides. medium-duration dwarf rice variety that susceptible to gall midge.

Insecticidal screening trials focused on the tungro virus need to be conducted

Anupama, and in Safri-17, in which the to isolate the insecticides that are most

low, the difference in yield was only the spread of virus infection.

numerical (see table). Laboratory studies are being

Silver shoots and grain yield in four rice varieties, India.

Treatment a Anupama Jaya Safri-17 12709 (W)

Silver shoots b (no./12.2-sq m plot)

Removal of silver shoots 16.3 126.0 6.8 Nil Cytrolane (1 kg a.i./ha) 12.3 67.3 6.4 Nil Control 21.0 139.0 9.6 Nil

Grain yield (kg/ha)

Removal of silver shoots 2711.0 2908.0 2391.0 2893.0 Cytrolane (1 kg a.i./ha) 2790.0 2746.0 2611.0 2966.0 Control 2640.0 2485.0 2162.0 2608.0

a Silver shoots removed and Cytrolane applied at 12 and 30 days after transplanting. b 45 days after transplanting.

Rice researchers win Thai society’s Award of Honor

Three rice researchers, Asanee Sarigabutr, Chai Prechachart, and Ben R. Jackson, have received the Award of Honor of the Agricultural Science Society of Thailand. The award was presented 11 February 1977 for the paper “Breeding dwarf varieties of rice for tolerance to deep water,” which appeared in the Thai Journal of Agricultural Science (v. 3, 1970).

IRRN 2:1 (February 1977) 9

Soil and crop management Root distribution of rainfed rices in the Cerrado of Brazil

Charles Allan Jones, rice physiologist, National Rice and Bean Research Center, Feijao, Caixa Postal 179, 74.000 Goiania - Goias - Brazil

Approximately 35% of Brazil’s rice is rainfed in the states of Goias, Minas Gerais, and Mato Grosso. Much of that is on highly weathered, clayey soils that are friable when wet, are porous, and retain little water. Upland yields are often limited by drought. An interdisciplinary program at the National Rice and Bean Research Center seeks to determine the variability of rooting habit of upland rice grown in those soils, and to develop techniques to screen plant materials for deep, well-developed root systems. Forty upland and lowland cultivars were planted in two oxisols: 1) a dark-red oxisol that had previously received heavy corrective lime and phosphate

applications and had approximately 60% aluminum saturation below 30 cm, and 2) an oxisol that had received no heavy lime and phosphate applications and had very low aluminum saturation. Root samples were taken 100 days after planting. Differences in leaf area index and rooting density (see table) were probably due to higher phosphorus levels in the plow layer of the first oxisol, which probably stimulated greater rooting density below 30 cm despite higher aluminum saturation at those levels. Intervarietal variability in rooting behavior was extreme in both soils; it was greater than that in plant height or leaf area index. Rooting density was positively and significantly correlated with plant height, but linear correlation coefficients were too low (0.18 to 0.54) to be used for predictive purposes. In general, Brazilian upland varieties had greater root development below 30 cm than other varieties tested.

Some plant characteristics at 100 days in 40 rice varieties on two oxisols, Brazil.

Aluminum Mean Mean rooting density Site saturation plant ht Mean (cm root/cu cm soil) at

0–30 cm 30–60 cm LAI a

in soil (cm)

National Rice and Bean 60% below 78 1.9 2.3 0.6 Research Center, 30 crn Goiania, Goias

Agricultural Research Very low at 77 2.6 3.4 1.6 Center for the all levels Cerrado, Planaltina, Federal District

Test of significance by analysis of variance ns *** *** ***

a LAI = leaf area index. ns = not significant; *** = significant at P=0.001.

Iron toxicity in Sierra Leone rice

I. Haque, Division of Soils, Njala University College, University of Sierra Leone, Njala, Sierra Leone

Iron toxicity is one of the serious problems reducing rice yields in flooded soils in Sierra Leone.

Bronzing usually occurs at maximum tillering. Roots are short, coarse,

reddish or dark brown, and have a few rootlets. Bronzing usually appears on older leaves. In severe cases the leaf edges turn dark brown and roll toward the midrib. In some cases, yellowing starts at the tips of the lower leaves, moving toward the leaf base. In severe cases the leaves are dark yellow to orange. The high iron levels inhibit the formation of new active roots, and the coating of

existing roots by iron oxides further reduces their nutrient absorption capacity.

Iron toxicity can be overcome to a considerable extent by:

1. growing rice cultivars that are resistant to iron toxicity;

2. draining the rice fields at critical growth stages (a method being developed by the Chinese Mission on a large scale in the country);

straw, which consists of silica and calcium; and

4. applying urea, basic slag, and muriate of potash as sources of nitrogen, phosphorus, and potassium.

Extensive work on the mentioned methods is being done by the Agronomy Department of Rice Research Station, Rokupr, under the Food and Agriculture Organization/International Institute of Tropical Agriculture Rice Project.

3. burning and incorporating rice

A test of several sowing methods in Nigeria

C. D. Newell, project agronomist, South Chad Irrigation Pilot Project, Chad Basin Development Authority, P.M.B. 1130, Maiduguri, Nigeria

Examination of different sowing techniques indicates that certain methods can contribute to reasonable rice yields with a minimum of land preparation. At South Chad Irrigation Pilot Project, sited on heavy montmorillonitic clay in northeastern Nigeria, seed that was broadcast directly into wheat stubble yielded 4,910 kg/ha. Broadcasting into a seedbed and incorporating with a light harrow yielded 5,060 kg/ha; rotacasting yielded 4,320 kg/ha. Direct seeding into flooded paddy yielded only 2,000 kg/ha.

Project is investigating cropping systems and cultural techniques for small holdings and for large mechanized production units. Its main irrigation scheme is under development.

The South Chad Irrigation Pilot

10 IRRN 2:1 (February 1977)

Terrazole as a nitrification inhibitor

Fred T. Turner, assistant professor, Soil and Plant Nutrition, Texas A & M University Agricultural and Extension Center, Route 5, Box 784, Beaumont, Texas 77706, USA

Laboratory experiments showed that- 4 00 ppm Terrazole (5-ethoxy-3 [trichloromethyl] -1,2,4- thiadiazole) was as effective as 25 ppm N-Serve in retarding nitrification in rice soils. Hence the potential of Terrazole

to increase nitrogen-use efficiency of urea-nitrogen by rice plants was evaluated under field conditions. Urea containing various proportions of Terrazole was applied to field plots just before the rice variety Labelle was planted on a Beaumont clay soil.

Terrazole had no measurable effect on grain yield, nitrogen-use efficiency (see table), or phosphorus or potassium content of foliage. It affected (5% probability level) the percentage of

Effect of Terrazole-treated urea on Labelle rice, 1975 growing season, Beaumont, Texas, USA.

Terrazole in urea Nitrogen Mean yield a N (%)

(kg N/ha)

N-use efficiency (kg grain/kg N

(t/ha) in leaf b (%) applied)

101 0 0.61 0.93 1.41

134 0 0.61 0.93 1.41

168 0 0.61 0.93 1.41

3.9 2.76 22 3.6 2.54 19 3.5 2.59 10 4.0 2.66 23

4.1 4.2 4.5 4.5

5.3 5.1 5.3 5.3

20 21 21 21

21 20 21 22

a LSD = 0.5.

nitrogen content of the most recently matured leaf at panicle differentiation. The zero-Terrazole treatment showed the highest nitrogen percentage in the leaf tissue. The 0.61% Terrazole slightly reduced nitrogen content. Nevertheless, increasing Terrazole levels tended to increase the nitrogen, suggesting that levels substantially higher than 1.41% may increase the nitrogen content of the foliage.

The nitrogen-efficiency values for preplant-applied urea were lower by about 10 kg grain/kg N than those normally obtained when the urea application was split. The NH 4

+ and NO 3 concentration in the soil after harvest was not affected by Terrazole rate.

The lack of effect of Terrazole on N-use efficiency under field conditions, compared with its effect in laboratory experiments, could be explained by these facts: (1) Terrazole rates were at least 50 times greater in the laboratory; and (2) although the laboratory experiments showed 100 ppm Terrazole to be most effective in inhibiting nitrification during the initial 30 days, the field experiments continued for about 120 days.

b % N in most recently matured leaf at panicle-differentiation growth stage.

Iron chlorosis in paddy nurseries

O. P. Meelu, S. Saggar, and G. S. Sekhon, Department of Soils, Punjab Agricultural University, Ludhiana, India

In the uplands, the raised-bed nursery method is not suitable for producing healthy, sturdy, and uniform seedlings which are a prerequisite for getting high yields. The flat-bed method of nursery raising, in which the field remains submerged, is conducive to reduction of iron and its better availability to emerging seedlings, thus preventing iron chlorosis in the paddy nursery. In a comparison of raised-bed and flat-bed methods at the Punjab Agricultural University Farm, Ludhiana, (1) seedlings

in the flat beds were green and healthy, (2) seedlings in the raised bed were chlorotic, and (3) weeds were more prevalent in the raised bed.

weekly intervals from the beds and analyzed for concentration of iron. Paddy seedlings from raised beds contained less iron than those from flat beds (see fig.). The iron content in the final sample, when the nursery was ready for transplanting, was deficient in the raised-bed nursery and sufficient in the flat-bed nursery according to the limits. fixed by Chapman (1966).

To check iron chlorosis, the nursery should be sown in flat beds and be kept submerged. If iron deficiency appears,

Seedling samples were removed at

Effect of method of nursery raising on iron concentration (ppm) in paddy seedling.

0.5–1.0% neutralized iron sulfate spray should be used regularly according to recommendations.

IRRN 2:1 (February 1977) 11

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 paragraphs and a table, figure, or photograph. They are subject to editing and abridgement to meet space limitations. Authors will be identified by name, title, and research organization.

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