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Contents
ENETIC EVALUATION AND UTILIZATION
erall progress
3 Heritability estimates of rice crosses
3 Improved rice variety released in the Philippines
3 Three new rice varieties for Nepal
4 Evaluation of IRTP nurseries
isease resistance
5 Resistance of rice cultivars to Xanthamonas campestris pv. oryzae at
6 Bacterial blight resistance under natural conditions
6 Varietal reaction to natural infection of rice tungro virus in Bihar
7 Identification of stable sources of resistance to blast in Nepal
8 Tainunga 68, the first BPH-resistant japonica cultivar developed in Taiwan
8 Correlations between silvershoots and panicle and tiller numbers
9 Resistance of modern rice varieties to the brown planthopper in Thailand
10 Reaction of rice cultivars to gall midge attack in Orissa
9 Reaction of selected rice varieties to whorl maggot Hyderllia spp.
10 Effect of nitrogen fertilizer levels and spacing on rice gall midge and
11 Influence of planting time on gall midge incidence at Aduthurai
11 Pests of hill rice in West Bengal, India
seedling and adult stages
sect resistance
leaffolder damage
her pests
11 Hirschmanniela oryzae and other nematodes found in rice paddies of the
Mekong Delta, Vietnam
rought resistance
12 Using check varieties to adjust visual scores for nonuniform soil drying in
drought resistance field screening
Adverse soils tolerance
12 Varietal tolerance for acid sulfate soils in North Vietnam
PEST MANAGEMENT AND CONTROL
Diseases
14 Relative humidity and nematode number and survival in rice seeds
14 Fungicidal control of rice grain discoloration
14 Epidemiology of brown spot disease of rice in Karnataka, India
15 Root-knot disease of rice in the Mekong Delta, Vietnam
15 Field soil as a source of rice stem nematodes
Insects
15 Parasite of the rice slug caterpillar
15 Sepedon sphegeus (Fabr.) (Sciomyzidae) and Notiphila spp. (Ep
dae ): alternate hosts of Trichogramma japonicum Ashmead, a ric
borer egg parasite
16 Populations of gall midge, whitebacked planthopper, and thrips on Pr
gati paddy17 Effects of silica level on whitebacked planthopper
17 Disruption of striped rice borer males orientation to pheromone t
SOIL AND CROP MANAGEMENT
18 Nitrogen management in flooded rice
18 Effect of seedling age an susceptibility to aluminum toxicity
18 Algae in rice fields of Chingleput District, Tamil Nadu, India
19 Comparison of zinc sulfate and Zn-EDTA as foliar spray
ANNOUNCEMENT
20 New rice publication
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Heritability estimates of rice crosses
B. K. Mandal, Rice Research Station, Chin-
surah, West Bengal, India
Heritability estimates of nine quantita-
tive characters were made using a half-
diallel cross involving seven parents: Sel.
ADT 27, Kataktara, ADT27. Padma,
IR8, TN1, and NC1626. The formula
used was: (D + H1 - H2 - F);
(D + H1 - H2 - F+ E).
The estimates show that the major
part of the total phenotypic variation for
plant height, grain-weight, length, and
breadth is due to additive genetic effects
(see table). Low estimates for effective
tillers, ear length, duration. grain yield,
and grain number indicate the influence
of nonadditive gene action in the expres-
sion of these characters.
Significant epistatic effects were
detected when genetic components were
analyzed for duration in crosses involv-
ing Sel. ADT27 or ADT27 as one par-
ent. By eliminating the arrays of crosses
of these two parents, the narrow sense
heritability was 78.4%, against 28.4% in
the presence of epistasis. This shows that
nonadditive gene action with epistasis
distorts the heritability estimate.
Selection for characters such as plant
height and grain weight may be done in
the early generation. Selection for char-
acters with low heritability, such as
effective tillers, ear length, duration,
grain yield, and grain number, should be
deferred till plants reach
homozygosity.
Improved rice variety released in the
Philippines
International Rice Research Institute
The Philippine Seed Board approved the
release of IR56 on 10 June 1982. IR56
was the selection IR13429-105-2-2-1
from the cross IR4432-53-3-3/Ptb 331//
IR36 made in 1976.
IR56 had superior performance in
lowland cooperative trials during 1980and 1981. Its yield potential is compara-
ble to that of IR36; it matures in 105
days. 2-3 days earlier than IR36; it has
long, slender, translucent grains with
high amylose and low gelatinization
temperature, and high milling recovery.
IR56 is resistant to all major diseases
and insects: blast, bacterial blight,
tungro, grassy stunt, green leafhopper,
and three biotypes of brown planthop-
per. Its resistance to tungro is higher
than that of IR36. In field trials in Min-
danao, IR56 showed tolerance for
ragged stunt virus. Its gene for resistance
to brown planthopper and green leaf-
hopper are different from those of IR36,
thus diversifying the genetic base of
improved materials being grown in
Asia.
Three new rice varieties for Nepal
K. P. Shrestha, agronomist, B. R. Akhikary,
assistant rice breeder, B. B. Shahi, and
S. Samoto, rice coordinators, National Rice
lmprovement Program, P.O. Box 4, Birganj,
Nepal
Through collaborative testing by the
International Rice Testing Program and
the national rice improvement program,
^ ^
^
^
^
^
Guidelines and Style
^
forIRRN Contributors
To improve communication and to speed theeditorial process. the editors of the International
Rice Research Newsletther (IRRN) request thatcontributors use the following guidelines and style:
Style
national units of measure (such as cavans, rai. etc. ).
Use the metric system in all papers Avoid
with small-scale studies, in grams per pot (g/pot) or
Express all yields in tons per hectare (t/ha) or,
grams per row (g/row).
or symbols used in a figure or table.
chemicals near the unit of measure. For example:
60 kg N/ha; not 60 kg/ha N.
the IRRN. Data in other currencies should beconverted to US$.
Abbreviate names of standard units of measurewhen they follow a number. For example 20 kg ha.
When using abbreviations other than for units ofmeasure. spell out the full name the first time ofreference, with abbreviations in parenthesis, then use
example: The efficiency of nitrogen (N) use wasthe abbreviation throughout the remaining text. For
tested. Three Ievels of N were .... or Biotypes of the
studied the biotypes of BPH in ....
brown planthopper (BPH) differ within Asia. We
number, even when the amount is less than 10. For
Express time, money, and measurement in
example: 8 years; 3 kg ha at 2-week intervals; 7%;
4 hours.
Write out numbers below 10 except in a series
containing some numbers 10 or higher and some
seven tractors: four varieties. But There were 4 plotsnumbers lower than 10. For example: six parts:
in India, 8 plots in Thailand, and 12 plots inIndonesia.
Write out all numbers that start sentences. Forexample: Sixty insects were added to each cage:Seventy-five percent of the yield increase is attributedto fertilizer use.
Guidelines
Define in footnotes or legends any abbreviations
Place the name or denotation of compounds or
The US dollar is the standard monetary unit for
Contributions to the IRRN should generally be
patterns involving rice. based on results of research on rice or on cropping
Appropriate statistical analyses are required formost data.
Contributions should not exceed two pages ofdouble-spaced, typewritten text. Two figures (graphs,
supplement the text. The editor will return articlestables, or photos) per contribution are permitted to
that exceed space limitations.
discouraged. Exceptions will be made only if Results of routine screening of rice cultivars are
screening reveals previously unreported information(for example, a new source of genetic resistance torice pests).
varieties are encouraged.
commercial chemicals and, when feasible, equipment.
contributions.
infection, degree of severity, etc.).
Announcements of the release of new rice
Use common not trade names for
Do not include references in IRRN
Pest surveys should be quantified with data (%
Genetic evaluation and utilizationOVERALL PROGRESS
Estimates of narrow-sense heritability of 9
characters in rice crosses at Chinsurah RiceResearch Station, West Bengal, India.
Narrow-sense
(%)
Character heritability
Plant heightEffective tillers
Far lengthDuration
51.425.624.628.4
Grain yield 38.4Grain number 19.8Grain weight 76.4
Grain length 86.6
Grain breadth 61.0
IRRN 7:4 (August 1982) 3
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Agronomic characteristics of newly released varieties in Nepal.
VarietiesAgronomic characteristic
Kanchan(IR3941) (IR2298)
Himali Taichung 176 Malika CH-45 Laxmi
(check) (Mala/J 15) (check) (check)
Days to headingDays to maturityPlant height (cm)
Panicle length (cm)Panicle no./m2
No. of filled grains/panicleFertility (%)1,000-grain wt (g)Straw wt (t/ha)Blast reactionUnhusked length (mm)Unhusked width (mm)Shape% of husking% of milling
Appearance of polished rice
Av yieldTesting station
103143
68
21400
818222.1
5.81R9.63.4
Slender/long78.3772.50
High/trans.
7.60Khumaltar
Kathmandu
110145
61
22275
919126.9
5.38R
10.33.4
Slender75.2272.00
High/trans.
7.18Khumaltar
Kathmandu
10314884
21265
907824.5
6.07S7.83.5
Medium/short80.2276.00
Medium/low
with white belly6.40
KhumaltarKathmandu
90120119
3051088521.3
S
22.3
8.52.8
Slender/med.78.172.4
High/trans.
4.9Parwanipur
8511512426.0
340738825.0
R
8.92.9
Slender/long77.571.5
Coarse withwhite belly
Parwanipur4.3
951259521 .0
405738924.9
R
9.22.9
Slender/long78.673.0
Medium witwhite belly
4.58Parwanipur
Nepal, three rice varieties were released
for general cultivation by the national
seed recommendation committee of
Nepal in 1982 (see table). IR3941-4-
which was named Kanchan, and
which was named Himali, are recom-
mended for temperate regions up to
PLP2B (CR126-42-5/IR2061-213),
1R2298-PLPB-3-2-1-1 B (CICA 4/ Kulu),
1,500 m altitude. Mala/J15 (CP-
SL02/ Sigadis), which was named Mal-
ika, is suitable as an early crop in irri-
gated areas and a monsoon season crop
in rainfed tropical areas.
and blast resistant. They have early
maturity and good eating quality and
are easily threshable. They are as non-
Kanchan and Himali are high yielding
lodging as the Taiwanese varieties grow
in the Kathmandu valley and in areas o
similar climates in temperate Nepal.
Himali is an aromatic variety with good
market value.
Malika is early and resistant to lodg-
ing. It has high seed dormancy during
rainy season harvesting, bacterial blight
resistance, and good grain quality.
Evaluation of IRTP nurseries
L. S. Mani, W. Wilfred Manuel, K. Gane-
san, and L. Anavaradham, Paddy Experi-
ment Station, Ambasamudram 627401,
Tamil Nadu, India
Two trials International Rice Obser-
vational Nursery (IRON) and the Inter-
national Rainfed Lowland Rice Obser-
vational Nursery (IRLRON) were
conducted during 1981 kar (Jun-Nov).
The nonreplicated observational plots
were not protected from pests and dis-
eases. For IRON, 242 genetically diverse
entries and 5 checks were screened. For
IRLRON, 128 entries (38 early and 90
late duration) and 7 checks were evalu-
ated. Cultivars were sown on 18 June
1981 and transplanted on 17 July. Plot
sizes were 3.25 m 0.75 m with 25-
25-cm spacing, 1 seedling/ hill. The fertil-
izer schedule was 100-50-50 kg
N-P2O5-K2O/ha.
For IRON, IR13540-56-3-2-1 (R.
Table 1. Performance of promising entries from the 8th IRON, Tamil Nadu, India.
Designation
EntryIR9763-11-2-2-3IR9830-26-3-3IR13525-43-2-3-1-3-2
IR15529-256-1IR17525-278-1-1-2IR19588-162-1
343 DTBKNBR 1031-7-5-4BR161-2B-54B2791-B-MR-145-1B3063-B-TK-72-2
Chianung Si-Pi. 661020IR5657-33-2-2-3IR9217-6-2-2-2-3IRl3149-71-3-2IR19661-293-1-3-2IR19670-57-1-1-3Kaohsiung Sen Yu 104
MTU 7029OR47-2 (Jajati)OR131-3-1RP 1057-184-5-3-3
R 35-2874
Suakoko 8(2526)X 2-D T
Grain yield
(t/ha)
5.57.05.75.5
5.76.2
6.25.7
6.65.56.0
5.56.46.15.95.57.05.96.67.4
6.65.5
6.46.05.9
% overADT36
(local check)
100.0127.3103.6100.0103.6112.7112.7
103.6120.0100.0109.1
100.0116.4110.9107.3100.0127.3107.3120.0134.5
120.0100.0
116.4109.1
107.3
Floweringduration
(days)
Plant ht
(cm)
1051039695
104105
95105
99
105103
9898
95105
989795
10595
100125
95100
95
94838984
8692
100
14687
131110
93108110108
96103104105122
88
11695
13492
CONTINUED ON OPPOSITE PAGE
4 IRRN 7:4 (August 1982)
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Table 1 continued
Grain yield% over Flowering
Designation ADT36 durationPlant ht
(cm)(t/ha) (local check) (days)
Chianung Sen Yu 13IR13540-56-3-2-1
RP825-45-1-3
CheckIR36
IR42IR1552ADT36 (local)
BR10(BR51-46-5)
5.97.8
6.2
3.03.93.3
1.45.5
Mean (m) 4.2Std. deviation 1.2m 5.4
107.3141.811 2.7
54.570.960.0
25.5100.0
76.421.898.2
9691
100
951041069896
94
7584
82105
8283
101
Table 2. Performance of promising entries from the 4th IRLRON, Tamil Nadu, India.
DesignationGrain yield
% of Flowering
Pelita I-1(t/ha) (local check)
duration(days)
Plant ht
(cm)
EntryBR10(BR51-46-5) 4.8 123.1 99 113
IR13146-45-2 5.5 141.0 96 121
IR13505-30-B-3 4.8 123.1 89 86
IR4744-295-2-3 4.7 120.5 92 87
IR5873-9-1 5.0 128.2 89 106
IR9763-11-2-2-3 4.7 120.5 99 106
BIET927 (RAU 38-12-3-1) 4.5 115.4 123 146
BKN6990-63 5.0 128.2 119 157
BR111-140-1-1 4.5 115.4 114 148
CR1030 6.4 164.1 116 151
C424-2 4.5 115.4 106 124
IR13365-253-3-2 4.5 115.4 117 111
IR13564-109-1 4.7 120.5 116 100
IR14632-65-2 4.5 115.4 116 112
IR14875-98-5 4.5 115.4 113 104
IR19083-22
-2-2 4.5 115.4 118 104
IR19431-72-2 5.4 138.5 103 94
IR3646-9-1-1 4.8 123.1 99 132
IR4819-77-3-2 5.4 138.5 106 133
IR4829-89-2 4.8 123.1 112 115
IR5857-64-IE-1-6 4.7 120.5 110 108
IR7545-27-3-2 4.7 120.5 106 100
IR9217-6-2-2-2-3 5.7 146.2 105 116
IR9763-11-2-2-3 4.5 115.4 106 109
KAU 2039 4.7 120.5 104 128
MR24 4.5 115.4 98 108
CheckIR36 3.6 92.3 87 76
Cisadane 3.6 92.3 105 108
Mashuri 2.9 74.4 107 139
IR46 2.7 69.2 115 93
IR1552 1.6 41.0 105 75
IR20 2.9 74.4 98 127Pelita I-1 (local) 3.9 100.0 103 114
Mean (m) 3.4 87.2
Std. deviation 1.1 28.2
m + 4.5 115.4
The International Rice Research Newsletter (IRRN) invites all scientists to contribute concise summaries ofsignificant rice research for publication. Contributions should be limited to one or two pages and no more thantwo short tables, figures, or photographs. Contributions are subject to editing and abridgement to meet space
limitations. Authors will be identified by name, title, and research organization.
Heenati/IR30(BPHS)//IR2823-399-5)
had the highest yield (7.8 t/ha in 121
days), 41.8% more than the local check
(Table 1). Yields of 30 other entries and
ADT36 ranged from 5.4 to 7.0 t/ha.
For IRLRON, CR1030 (Waikoku/
CR 1014-211) had the highest yield
(6.4 t/ha in 146 days), 64.1% more thanthe best check (Table 2). Yields of 24
other entries ranged from 4.5 to
5.5 t/ha.
season was whorl maggot, within a
threshold level of 20%. There was no
disease incidence. Based on grain yield
and ancillary characters, 28 entries from
IRON and 3 entries from IRLRON, all
of medium duration, have been selected
for further testing.
The only insect observed during the
GENETIC EVALUATION AND UTILIZATIO
Disease
resistance
Resistance of rice cultivars toXan-
thomonas campestris pv. oryzae at
seedling and adult stages
S. C. Sharma, R. G. Saini, and A. K. Gupta,
Genetics Department, Punjab AgriculturalUniversity, Ludhiana, India
The clipping method was used to inocu-
late 20-day-old seedlings of 428 cultivars
with a highly virulent isolate ofXan-
thomonas campestris pv. oryzae. Aver-
age lesion lengths of the seedling leaves
were recorded 15 days after inoculation.
Adult stage damage was rated on the
standard evaluation scale for rice (0-4
resistant and 4.1-9 susceptible).
Thirteen cultivars showed resistance
at both seedling and adult stages (seetable). Cultivars carrying Xa 1, Xa 2, X
3, and xa 5 were resistant at seedling as
well as the adult stage. IR20 carrying the
gene Xa 4 was susceptible at both
stages.
the seedling stage only ARC 6172,
ARC 6181, ARC 6615, ARC 7251, B-
Some cultivars showed resistance at
76, IR15529-26-1-1-2, IR15529-253-2-2-
2, NCS-2003, NCS 2014, NCS 2039,
IRRN 7:4 (August 1982) 5
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NCS 2041, NCS 2043, NCS 2044, NCS
2046, NCS 2048, NCS 2049, NCS 2055,
NCS 2057, NCS 2072, NCS 2107, and
Palman 579. Lesion lengths ranged from
2.2 cm to 3.6 cm. Some cultivars were
susceptible as seedlings but resistant at
adult stage ARC 5913, ARC 5938,
ARC 5951, ARC 6248, ARC 10602,ARC 11281, Denga Faram, IR2035-117-
3, IR15705-199-3-3, Jhinwa, Jikkoku/
Serpheke chil 52-102, Mudgo, NCS 320,
NCS 332, NCS 338, NCS 335, NCS
2015, NCS 201 8, Sinna Sivappu,
T 1426, Vallathil Cheera, and Vellai
Langayan. Disease scores ranged from
2.2 to 3.8.
Disease reaction of some rice stocks at seedling and at adult plant stage at Punjab, India.
Lesion length (cm) Scores at
Mean Range (0-9 scale
Stock or cultivar Source at seedling stage adult stag
MTUl5/Waiseakokku-127 CRRI 3.65 2.0-7.0 2.7ARC6044 CRRI 3.75 2.5-5.0 4.0ARC11321 CRRI 3.68 2.0-6.0 3.4ARC11367 CRRI 2.75 2.0-4.5 2.2IET6123 CRRI 3.40 2.5-4.5 3.4
NCS2001 CRRI 3.50 1.5-5.0 3.0 NCS2009 CRRI 1.43 0.5-2.5 3.2 NCS2039 CRRI 2.48 2.0-3.5 3.7 NCS1604 CRRI 3.98 2.0-8.0 3.4Kogyoku (Xa 1) IRRI 1.50 1.0-2.0 0.8Tetep ( Xa 1 + Xa 2) IRRI 1.20 0.5-2.5 1.4
Wau Qikoku-3 ( Xa 3) IRRI 2.23 1.0-4.5 1.7
IR1545-339 ( xa 5) IRRI 2.95 2.0-4.5 1.3IR20 ( Xa 4) IRRI 4.78 3.0-7.0 5.6TN1 (susceptible check) 16.68 8.5-26.5 6.5
Bacterial blight resistance under During the 1980 and 1981 wet seasons,
natural conditions bacterial blight appeared in epidemic
form in several pockets of the Chhatis-
R. K. Sahu, junior breeder, M. N. Shrivas- garh region. During the high natural
tava, rice breeder, V. N. Sahu and B. P. infection in 1981, germplasm accessions
Chaudhary, junior breeders, and P. S. Shri- of early and medium duration were
vastava, professor of plant breeding, Zonal screened for resistance, using the Stand-
Agricultural Research Station, J. N. Agricul- ard Evaluation System for Rice scale.
tural University, Raipur, 492006, M. P., Of 6,129 cultivars screened, only 1India scored 1, 24 scored 3, and the others 5-9
Table 1. Resistance of germplasm accessions of rice of different maturities for natural bacterial
blight epidemic in Raipur, M.P. India.
Maturity group
Accessions (no.) with given bacterial blight
screened resistancea score
(no.) 1 3 5 7 9
Extra early (up to 90 days) 558 0 0 14 122 422
Very early (91 to 110 days) 496 0 3 57 138 298
Early (1 11 to 125 days) 2313 1 11 205 833 1263
Medium (126 to 140 days) 2762 0 10 744 1058 950
Total 6129 1 24 1020 2151 2933
aStandard Evaluation System for Rice, % hills affected: 1 = less than 1%, 3 = 1 -5%, 5 = 6-25%, 7 =
26-50%, 9 = 51-100%.
(Table 1). No seed could be harvested
from several highly susceptible lines. No
very early variety was resistant.
The 25 cultivars with scores of 1 and
3 (Table 2) have been selected for
further tests under artificial inoculation
They have also been crossed with varie-
ties carrying known resistance genes to
study their allelic relationship.
Table 2. Bacterial blight-resistant varieties atRaipur, M.P., India.
Karhani KechanaBenikath KhurabanBhatapyagi Liktimati
Badshahbhog RuingiBhatagunda RotadChingerchopa Rageem 14Chinee Kapoor Safed jeeraDilbaksa SatakaGotaka SLOJalkesar Tikurdhan
Kesariya VishnubhogKosma X 11Kariyakora
Varietal reaction to natural infection Table 1. Varietal reaction to rice tungro virus at Bihar, India.
of rice tungro virus in Bihar Resistancescorea
Released varieties Promising varieties
B. N. Singh, senior rice breeder, Y. Prasad,
assistant rice pathologist, and S. P. Sahu,
assistant research officer (rice breeding), BR9, Katarni, IR20 Rajendra Agricultural University, Bihar,
Pusa 848125, India
3 Pusa 2-21, CR44-35 (Saket 4) Pusa 33, TCA4, TCA177Ratna, BR34, Janaki (64-117),
5 Rajendra Dhan 201 TCA80-4, IET6263, RP1045-403-1
7 Rasi (IET1444), BR14, BR8, BIET927, BIET1107, IET5656, ET5882,
Rice tungro virus infection under natu-
ral conditions was very high during
1980-81 kharif. The disease appeared the
first week of August in transplanted
Taichung Native 1 in a dryland field and
6 IRRN 7:4 (August 1982)
Type 3, Pankaj, Sita, PR106 FH132
Prasad, Bala, Cauvery, TCA62-68, TCA62-10, BIET1048,
NC1626, Improved SOna BIET821, IET2707, CRMS37, IET5883,
9 Jaya, IR8, Mahsuri, BR46, UPR82-1-7, IET6155, BIET724, BG90-2,
IET5890, IET6314, IET5897, IET6212
a1980 Standard Evaluation System for Rice scale of 0-9: 3 = 6-10% incidence, 9 = 81-100%.
Accessions
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Table 2. PVT3 and PVT4 entries with resistanc
to rice tungro virus at Bihar, India.
Scorea Cultivars
1 RP1125-1526-2-1-1, RP1125-1526-2-2-3, RP1125-1526-3-2-4, RP1125-
1528-1-4-3
3 CR161-42-16, CR186-1, CR236-63,
CR276-5, RP1064-14-2-4, IR42,R8-2535, P837, P858, SKL6,Pusa 2-21
5 CR98-7216-CRP 34, CR149-9177-CRRP-19, CR188-10, RP974-29-3-2, RP1045-211-7-3-4, RP1064-
14-2-3, RP1091-24, UPR243-63-1,
AD9408, AD77496, P835, PY-1,
Sonalee, RSB40
a1980 Standard Evaluation System for Ricescale of 0-9: 1 = less than 1% incidence, 5 = 21-
30%.
in transplanted Bhutahi in a deepwater
field. Vector green leafhopperNephotet-
tix virescens populations had been in-
creasing during July. The disease later
spread to varietal demonstration plots
and other yield evaluation trials. The
disease diagnosis was confirmed by the
virologist, Central Rice Research Insti-
tute, Cuttack.
No control measures were taken. Dis-
ease incidence was so severe that yields
from some varieties were very low.
Released and promising varieties were
scored for resistance to tungro according
to the Standard Evaluation System for
Rice (Table 1).
In the All India Coordinated Rice
Improvement Program, severe infection
occurred in 2 trials, PVT3 and PVT4
with 128 entries grown in 2 replicationsin each trial. Four entries from the
RP1125 cross (RPW6-13/Ptb 2) showed
resistance, another 11 showed moderate
resistance, and 15 were intermediate
(Table 2). All others were susceptible to
highly susceptible.
Tungro reappeared at Pusa and Patna
during 1981-82 kharif.
Varietal recommendations for North
and South Bihar, where tungro occur-
rence is becoming a problem, have been
changed. Depending upon land situa-
tions, the newly recommended varieties
are Pusa 2-21 and CR44-35 for dryland
transplanting, Ratna and Rajendra
Dhan 201 for midland transplanting,
BR34 for wetland rainfed, and Janaki
for semideep water.
Few resistant lines are available for
wetland irrigated fields. Two lines.
IET6263 (CR262-19) and RP1045-403,
have been found promising. ResistantBR9 and Katarni fragrant, short-
slender, photoperiod-sensitive rices
Identification of stable sources of
resistance to blast in Nepalthe Kathmandu valley and in other hilly
regions of Nepal, have resulted in blast
may be recommended. Type 3, the onlyvariety recommended for export, has
been found susceptible to tungro.
and in lines derived from crosses with
them. Blast reactions were scored
B. P. Upadhyay, assistant plant pathologist, becoming a major source of yield losses. according to the Standard Evaluation
It has been possible to identify blast- System for Rice.and B. B. Shahi, national rice coordinator,
National Rice Improvement Program, Bir- resistant sources by using IRRI mass-
ganj, Nepal screening techniques (see table). These
lines are used extensively in Nepalese
Use of modern Taiwanese ponlai varie- rice breeding programs. During 1977-81,
ties and high doses of nitrogen fertilizer, high levels of blast resistance were found particularly in the temperate region of in cultivars Tetep, Dawn, and Carreon
Individuals, organizations, and media
who wish additional details of
information presented in IRRN should
write directly to the authors.
Highly resistant entries observed in blast nurseries at 2 sites in Nepal.
Blast scorea
Cultivar or lineSource
Khumaltar (1,327 m alt)of resistance
Parwanipur (100 m alt)
1977 1978 1979 1980 1981 1977 1978 1979 1980 1981
CIAT-ICA 5 TetepIR1544-238-2-3 Tetep
IR1416-128-5-8 TetepIR1416-1-42-2-3-3 TetepIR1905-PP11-29-4-61 TetepIR1905-81-3-1 TetepIR3259-5-160-3 Tetep
74-5461 TetepIR5533-56-1-12 Tetep, CarreonIR5533-PP850-1 Tetep, CarreonIR5533-PP854-1 Tetep, Carreon
IR9660-00948-1 DawnTetep (check)
Carreon (check)
Dawn (check)
Sankharika (susceptible check)Pokhareli Masino (local resistant)Chainan 2 (commercial)Chainung 242 (commercial)Taichung 176 (commercial)
111112
1
21112
b1
4
92888
111112
2
1111
14
1
192
779
000b
0
0
b0bb
b
0
0092555
32
1132
2
b13
12
11b
9164
7
0000
000
0000
00
02
93688
1111114
132
3
14
bc
91344
11
111
11
111
1
11
1192113
12
b1
2
5b
b
b3
bb
154
92331
c
1
111
b
1
511
1
1
b3
9
0444
c
00cc
00
0
30000
0
1491556
a Standard Evaluation System for Rice: 0 = no lesions, 9 = all leaves dead. bEntry not used. cMissing.
IRRN 7:4 (August 1982) 7
b
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GENETIC EVALUATION AND UTILIZATION
Insect resistance
Tainung 68, the first BPH-resistant Table 1. Resistancea to disease and insect pest of Tainung 68 in Taiwan, China.
Japonica cultivar developed inTaiwan Cultivar Blast
Neck Bacterial Brown planthopperb
blast blight15 DS 45 DS
W. L. Chang, Chiayi Agricultural Experi- Tainung 68 MR-S MR-S MR-S S R
ment Station, TARI, Chiayi, Taiwan, ChinaTainung 67 (check) S-HS S-HS MS S S
aR = resistant, MR = moderately resistant, S = susceptible, HS = highly susceptible. bDS = days afte
Japonica cultivars, which occupy more seeding.
than 90% of the planted area in Taiwan,
are susceptible to brown planthopper
(BPH). Efforts to transfer BPH resist-
ance from indica to japonica rices have
resulted in the release of BPH-resistant
selection Chianung 250, the first BPH-
resistant japonica cultivar developed inTaiwan. The Subcommittee on Varietal
Registration of the Taiwan Rice
Improvement Council unanimously
recommended its release 1 June 1982.
The new cultivar, officially named
Tainung 68, was selected in 1976 from
the cross Nankai-yu 114/// Nankai-yu
77//Tainan 52/ASD 7, made in 1973 at
Chiayi Agricultural Experiment Station.
The resistance to BPH inherited from
Correlations between silvershootsand panicle and tiller numbers
Prem Chand and R. C. Acharya, Ranchi
Agricultural College, Kanke, Bihar, India
834006
Gall midge infestation is thought to
stimulate profuse tillering. Therefore the
association among silvershoots and
tiller and panicle numbers was assessed.
Data on the three attributes were taken
on variety Sita on 27 randomly selected
hills from each of 11 plots, 10 treated
with insecticides and 1 untreated. Datawere collected after the emergence of
panicles, about 1 month after insecti-
cides were applied.
Total correlation coefficients between
silvershoots and tillers, silvershoots and
panicles, and tillers and panicles and
partial correlation between silvershoots
and panicles were determined. Estimates
of total and partial correlation coeffi-
cients for the 11 treatments were pooled
8 IRRN 7:4 (August 1982)
Table 2. Agronomic performance of Tainung 68 in Taiwan, China (av of 1979-81).
Maturity (days) Height (cm) Yielda (t/ha)
1st 2d 1st 2d 1st 2dcrop crop crop crop crop cro
Cultivar
Tainung 68 115 97 94 99 6.3 4.Tainung 67 (check) 116 98 96 103 6.8 4.
aRecorded at Pintung, southern Taiwan.
ASD7 is expressed at late growing Currently grown cultivar Tainung 67
stages. Tainung 68 also has some resist- is susceptible to BPH, which occurs
ance to blast and bacterial leaf blight severely in southern Taiwan during the
diseases (Table 1). Most agronomic hot, wet second crop season. Tainung 6
characters are desirable, with good is a promising alternative and an impor
yields in the second crop, particularly in tant source of BPH resistance in breed-
the southern part of the island (Table 2). ing programs.
using a multiple covariance model.Tillering correlated positively with sil-
vershoots (see table). Estimates of corre-
lation coefficients varied from 0.1326 to
0.8402, significant in 9 cases. The pooled
correlation coefficient was 0.4718, signif-
icant at the 0.01 level.
Tillers correlated positively with pani-
cles. Estimates of coefficients variedfrom 0.1731 to 0.6898, significant in 9
cases. Estimate of the pooled correlatio
coefficient (0.5518) was significant at th
0.01 level.
Of 11 estimates of the correlation
coefficient between silvershoots and pan
icles, only one was significant. This sug
Estimates of total and partial correlation coefficientsa between silvershoots, tillers, and panicle
numbers at Bihar. India.
Treatment r12 r23 r13 r13 2
Foratox 0.8402** 0.6056** 0.0880ns 0.9751**
BPMC 0.1326ns 0.5227** 0.0096ns 0.0936nsEkalux 0.4002* 0.6898** 0.1438
ns 0.3536*
Carbofuran 0.5604** 0.3551ns
0.2573 ns 0.5608**
Carbaryl 0.7960** 0.1731ns 0.0828 ns 0.6428**
Lindane 0.4099* 0.5548** 0.2604ns 0.6428**
Diazinon 0.6723** 0.5035** 0.4743* 0.2125ns
Tamaron 0.3408ns 0.6370** 0.2242ns 0.6089**
CFVP 0.5467** 0.5563** 0.2653ns 0.2444ns
Monocil 0.5467** 0.5563** 0.2095ns 0.7381**
Control 0.5581** 0.4650* 0.0937ns 0.2257ns
Pooled 0.4718** 0.5518** 0.0029 0.3156*
a l = silvershoots, 2 = tillers, 3 = panicles. * = significant at 5% level. ** = significant at 1% level. ns
not significant.
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9/20
gests no association between the two
characters. The pooled estimate was also
nonsignificant.
The absence of correlation between
silvershoots and panicles and the signifi-
cant correlation between silvershoots
and tillering support the popular belief
that silvershoots increase tillering, com-
pensating for panicle loss. But it also
may be argued that a hill containing a
greater number of tillers is more sus-
ceptible to gall midge attack, because it
provides more points. As such, more
tillers would be the cause of silvershoots.
Estimates of partial correlation coeffi-
cients between silvershoots and panicles
after eliminating the effect of tiller dif-
ferences were made. All estimates except
one were negative, varying from 0.9751
to -0.0936 and significant in 5 cases. The
only positive estimate was also small
and nonsignificant. The pooled estimate
of the partial correlation coefficient was
0.3156, significant at the 0.05 level.
A partial regression analysis using the
covariance model y = f(Tr,; X1 X2 X3 )
wherey stands for panicle, X1 for silver-
shoot, and X2 for tiller estimated the
loss due to silvershoots for the pooled
data. The result wasy = 1.84 0.3975
X1 + 0.4584 X2 . The estimate ofR, the
multiple correlation coefficient, was
0.7791, significant at the 0.01 level. Both
partial regression coefficients were also
significant at 0.01. The partial regression
equation suggests that the expected net
effect of a unit increase in the number of
silvershoots is a drop of 0.4 in the
number of panicles.
Resistance of modern rice varieties
to the brown planthopper in
Thailand
Nipha Chansrisommai, Rice Insect Pest
Branch, Entomology and Zoology Division,Department of Agriculture, Bangkhen,
Bangkok, Thailand; and Weerawooth Katan-
yukul, Entomology Department, Interna-
tional Rice Research Institute
Outbreaks of the brown planthopper
(BPH) Nilaparvata lugens have caused a
rapid spread of ragged stunt disease in
the central Thailand plain since 1973.
But RD9, the first BPH-resistant variety
released in 1975, has not been widely
accepted because of its susceptibility to
many diseases and its poor grain quality.A greenhouse experiment was
designed to determine the resistance
mechanism in three varieties released in
1981 RD21 (DML 105/Nang-Mol
S-4//IR26), RD23 (RD7/IR32//RD1),
and RD25 (DML 105/IR2061-214-2-3-3
// DML l05/IR26) and in an RD7
mutant developed by gamma-irradiation
which had shown BPH resistance.
Experimental procedures were those
used in the International Brown Plant-
hopper Biotype Collaborative Project.
A free-choice feeding experimentshowed no significant difference in the
number of insects feeding on resistant
and susceptible varieties. Antibiosis was
indicated: BPH survival after 12 days
was 6% on RD21, 7.5% on RD7
mutant, 14% on RD9, 20% on RD23,
20% on RD25, and 36% on RD1 (Fig.
1). The population buildup study also
confirmed antibiosis reaction in RD21,
RD23, RD25, and RD7 mutant. RD25
1. Survival of brown planthopper on modern rice
varieties in Thailand.
2. Population buildup of brown planthopper(BPH) on different rice varieties 4 weeks afterrelease of 3 pairs of adults, Thailand.
showed the highest resistance (no popu-
lation increase) to BPH; RD1 produced
247 insects 4 weeks after release of 3
mated BPH pairs (Fig. 2).
Reaction of selected rice varieties to
whorl maggot Hydrellia spp.
S. Uthamasamy and P. Karuppuchamy,
Tamil Nadu Rice Research Institute,
Aduthurai, India
During 1981 kharif, 22 varieties were
grown in 20-hill rows. Two plantings
were done, one at the usual time and the
second 15 days later. Recommended
management practices were followed.
The number of whorl maggot-
damaged leaves was recorded on
10 hills/ variety at 30 and 45 days after
transplanting (see table). Ptb 12 and Ptb
21 had the least damage, Ptb 19 the
most damage.
Incidence of whorl maggot damage on rice
varieties at Aduthurai, India.
Whorl
Variety maggotincidence
(%)
ARC6632 10.1Banglei 8.5Chemban 9.3Chempan 11.6Chitteri 10.7Cheriya Chitteri 11.4Kula Peruvela 11.4
Leaung 152 11.7NagrasalPtb 12
12.9
Ptb 193.4
Ptb 2116.5
Ptb 335.5
13.0Parakulam 10.5SulaiT 10
12.98.8
Vellai Langayan 11.4Valsara Champara 14.3Vellathil cheera 11.7Lal Basumati 10.3TN1 (susceptible check) 11.1
L x H/2-281 12.4
IRRN 7:4 (August 1982) 9
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Reaction of rice cultivars to gall
midge attack in Orissa
B. C. Jena, research scholar, and N. C. Pat-
naik, entomologist, Orissa University of
Agriculture and Technology, Bhubaneswar;
and N. Panda, senior research fellow, Ento-
mology Department, International RiceResearch Institute
Rice gall midge Orseolia oryzae is a
serious pest in the wet season, but activ-
ity is also observed in the dry season in
areas receiving perennial flow irrigation.
Varieties in the coastal tract appear to
differ in level of susceptibility from var-
ieties in the inland districts.
A trial in the 1980 and 1981 wet sea-
sons at three representative sites
Bhubaneswar (Pun district), Rampur
(Bolangir district), and Chakuli (Sam-
balpur district) studied cultivar reac-
tions to variable insect population pres-
sure. The trial had 6 donor cultivars, 5
resistant varieties, 8 promising cultivars,
and 3 susceptible checks grown in a
completely randomized block design
replicated 3 times with 100 hills/replica-
tion. Silvershoot infestation was meas-
ured at 55 days after transplanting.
Siam 29 and Eswarkora exhibited
higher levels of silvershoot incidence at
all three sites in both years (see table).
Infestation level in Leuang 152, Ptb 18,
and Ptb 21 was less than 1%. Resistant
Effect of nitrogen fertilizer levels and
spacing on rice gall midge and leaf-
folder damage
R. Saroja and N. Raju, Paddy Experiment
Station, Tirur 602025, Chingleput District,
Tamil Nadu, South India
The effect of four nitrogen levels andthree plant spacings on rice pest damage
was studied in a field trial at Tirur dur-
ing the samba season, July-August to
November-December 1979-80. The two-
factor experiment was laid out in a ran-
domized complete block design with
three replications.
planted in 9-m2 plots with 50 kg
P2O5/ha and 50 kg K2O/ha. The crop
Thirty-day-old seedlings of IR8 were
10 IRRN 7:4 (August 1982)
Reaction of rice cultivars to gall midge infestation at 3 locations in Orissa, India, 1980 and1981.
Av silvershoots (%) at 55 DT a
Cultivar Parents Bhubaneswar Rampur Chakuli(Puri) (Bolangir) (Sambalpu
DonorsEswarkora 1.10 3.34 2.89
Leuang 152 0.00 0.07 0.24Ptb 18 0.03 1.10 0.55Ptb 21 0.00 0.19 0.19
Siam 29 5.69 7.28 10.18W1263 1.10 1.08 0.60
Resistant varietiesKakatiya IR8/W1263 4.95 2.30 4.29Shakti Ptb 18/Ptb 21//IR8 1.21 3.24 1.99
Phalguna IR8/Siam 29 0.41 1.40 0.46Surekha IR8/Siam 29 0.38 1.40 1.04Samlei IR8/Leuang 152 0.16 0.26 0.07
Promising cultivarsORSJR-214 IRI/Leuang 152 0.36 0.96 0.71
OR127-3 RPW 6-13/Hema 0.00 0.06 0.00
ORl40-9-3 RPW 6-13/CR94-MR 1550 0.00 0.15 0.55
ORl32-3-1 Rajeswari/CR57 0.13 0.33 0.89
CR199-1 RPW 6
-1 3/Supriya 0.07 0.00 0.13
CR401-6 Vijaya/CR94-15 12-6 0.95 1.29 1.47
CR404-24 CR94-1512-6/Pusa 2-21 0.10 0.00 0.06
RP8-9 IR8/W1257 10.19 13.08 4.46
Susceptible checks
Jaya TN1/T141 13.40 23.26 22.32IET5656 RPW 6-13/Sona 16.76 12.78 16.42RP356-112-1-1 IR8/Siam 29//Ptb 18/Ptb 21 17.10 18.07 8.19
aMean of 3 replications. DT = days after transplanting.
variety Kakatiya had high infestation at tion among donors, resistant varieties,
all three sites. Shakti had high level of promising cultivars, and susceptible
infestation only at Rampur. RP8-9 had checks with respect to test sites was v
high infestation at all three sites. low. Fluctuations in silvershoot inci-
Infestation in susceptible varieties was dence were mostly ascribable to envir-
very high. Variability in level of infesta- onmental influences.
Effect of nitrogen fertilizer and spacing on gall midge and leaffolder damage at Tirur, India, 1979-8
samba.
Nitrogen
(kg/ha) 10 x 10cm
0 11.2
75 14.0150 15.2225 14.8
Av 13.8
CD for N levelCD for spacing
CD for interaction
20 x 20
cm
8.8
11.010.312.2
10.5
30 x 30 Avcm
7.9 9.310.8 11.910.5 12.010.7 12.0
10.0
2.372.05
4.12
10 x 10 20 x 20 30 x 30 Avcm cm cm
24.4 20.2 18.7 2148.3 29.1 23.3
48.0 30.8 24.847.4 37.6 31.9 39
42.0 29.4 24.7
11
received no insect protection. 75 DT.
Gall midge damage was measured as Damage by gall midges and leaf-
the number of silvershoots to total tillers folders was rather high and increased
on 50 hills/ plot at 60 days after trans- significantly when nitrogen was added
planting (DT). Leaffolder damage was the plot (see table). Damage also
measured as the number of leaves dam- increased significantly at closer
aged to total leaves on 25 hills/plot at spacings.
5.
33
34
6.
Gall midge silvershoots (%) Leaffolder-damaged leaves (%)
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Seven species of nematodes have been
found in rice plants and soil in the
Mekong Delta: Dirylenchus angustus.
Aphelenchoides besseyi, Meloidogyne
graminicola, Hirschmanniella oryzae
spp, Criconemella sp., Tybenchorhyno-hus sp., Helicotylenchus sp.
Populations of H. oryzae were studie
from about 1,000 soil samples and rice
roots from 100 paddy fields. Sampling
was done from tillering in the 1981 rainy
season main crop to tillering in the 1982
second crop. Main crop varieties were
Tau-bun, Tauchen, Nang-quot, Chum-
ran, Gay-xe, Chet-cut, Lem-lun, Bang-
senx. Second crop varieties were IR36,
Rice is grown in the hilly areas of
Darjeeling district on bench terraces up
to 1,335 m altitude. Annual precipita-
tion ranges from 2,800 to 3,900 mm.
The annual maximum temperatures
range from 15 to 24 C and minimum
temperatures from 75 to 19 C
depending on the altitude. Only one
medium to late duration rice crop is
grown during the monsoon season.
Economically important insect pests of
hill rice are in the table.
P. K. Banerjee and P. B. Chatterjee, Rice
Research Station, Chinsurah 712 102, West
Bengal, India
Pests of hill rice in West Bengal,
India
Influence of planting time on gall
midge incidence at Aduthurai
P. Karuppuchamy, S. Uthamasamy, and G.
Chakkaravarthy, Tamil Nadu Rice Research
Institute, Aduthurai 612 101, Tamil Nadu,
India
Rice gall midge Orseolia oryzae inci-
dence was measured on CO 40 in the
samba season and on IR20 in the tha-
ladi season. Plot size was 50 m2 with 4
replications. The number of silvershoots
in total tillers was counted.
During the samba season, maximum
gall midge incidence was on the crop
planted 1 September 1981 followed by
crops planted on 16 September and 16
August (see figure). Incidence was less
on crops planted on 2 and 17 October.
During the thaladi season, maximum
incidence was on the crop planted 16
September.
The 50- to 70-day-old crop in the
samba season and the 30- to 60-day-old
crop in the thaladi season were more
prone to gall midge infestation.
Gall midge incidence during samba and thaladi
seasons in Tamil Nadu, India.
Insect pests of hill rice in West Bengal, India.
Insect Seasonal incidence
Stem borersWhite stem borer Jul-Oct, peak seasonScirpophaga innotata in September
Gold-fringed borerChilo auricilia (Dudgeon)
(Walker)
Rice bug
Leptocorisa acuta
(Thunberg)
Aug-Oct
Green leafhopper Nephotettix virescens
Nephotettix nigropictus Jul-Oct
(Distant)
(Stl.)
Big white leafhopperTettigella spectra Distant Oct-Nov
Leaffolder
Cnaphalocrocis medinalis Sep-Nov(Guenee)
Gall midge
Orseolia oryzae(Wood-Mason)
Swarming caterpillarSpodoptera mauritia
(Boisduval)
Aug-Oct
Jul-Aug
Economic importance
Damage varies from 30% to 80% oftillers.
Loss estimated at 25-35% of
panicles.
Minor.
Minor.
At altitudes from 650-1000 m
about 25-40% leaves damaged. Late
crop most damaged.
At altitudes below 1000 m, 25-30%silvershoots.
Humid areas near perennial springsat lower altitudes are more infestedseedling damage.
GENETIC EVALUATION AND UTILIZATION
Other pests
Hirschmanniella oryzae and other
nematodes found in rice paddies of
the Mekong Delta, Vietnam
Dang-ngoc Kinh and Bui-yan Ngoc, Plant
Protection Department, University of Hau-
Giang, Vietnam
IRRN 7:4 (August 1982) 1
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IR42, IR2823-399-5-6, IR9129-163-3-2-
2, IR9129-192-2-3-5, and IR2307-247-2-
2-3. Nematodes were found in all
samples.
Populations in 50-gram root samples
of local varieties ranged from 12 to 380 ing, 860 to 11,200.
at tillering, increasing to 50 to 7,000 at Populations in 100-ml soil samples
flowering, and to 300 to 7,500 at ripen- averaged 71 throughout the sampling
ing. In the second crop, populations at period, with a range of 5 to 450
transplanting were 204 to 9,000; at tiller- nematodes.
GENETIC EVALUATION AND UTILIZATION
Drought resistance
Using check varieties to adjust visual
scores for nonuniform soil drying in
drought resistance field screening
Nopporn Supapoj, Chaluay Boonwite,
J. C. OToole, S. K. De Datta, and
B. R. Jackson, joint contribution of the Rice
Division, Dept. of Agriculture, Bangkok-9,
Thailand; The International Rice Research
Institute, Los Baos. Philippines; and Rocke-
feller Foundation/IRRI Cooperative Pro-
jects with the Ministry of Agriculture and
Cooperatives, G. P.O. Box 24.53, Bangkok,
Thailand.
In many areas of monsoon Asia, the dry
season allows use of irrigation (surface
or sprinkler) to control timing (growth
stage) and duration of water stress in
drought resistance screening of germ-
plasm in the field. But variability in soil
drying results in problems in interpreting
visual scores among entries. Using soilmoisture measurements (tensiometers,
gypsum blocks, or gravimetric sampling)
to indicate relative soil water deficits
within a field has inherent technical
problems and is not generally
satisfactory.
A method using frequently spaced
check varieties to adjust or normalize
field screening results for heterogeneity
of soil drying has been developed.
Field screening for drought resistance
was conducted in the 1980 dry season at
the Klong Luang Rice Experiment Sta-tion, Thailand. Localized deviations of
IR20 (susceptible check) and BKN6986-
108-3 (local resistant check) from their
overall means were used to adjust scores
of entries in nearby plots. The figure
illustrates the heterogeneity of soil dry-
ing across the field that was identified by
the response of check varieties and devia-
tions from their respective overall
means.
12 IRRN 7:4 (August 1982)
Variation in soil drying
across field is illustrated
by changes in responses
of IR20 (susceptible
check) and BKN6986-
108-3 (resistant check).
IRRI.
Statistical analysis of original (A) and adjusted (B) visual drought resistance scores of 77 entries in
1980 dry season field screening for drought resistance at Klong Luang Rice Experiment Station,
Thailand.
CV (%) F-valueDMRT (5%)
discrimination
range (no.)
A 0.5603 29.9 2.12** A-G (7)B 1.0377 24.0 3.08** A-M (1 3)
At any place in the field, the average uniform soil physical properties or by
of the check varieties deviations from inequity of irrigation water
their respective means was applied to the distribution.
scores of adjacent entries, normalizing-
varietal response for soil moisture hete-
rogeneity. The ratio of varietal variance
) to expenmental variance was
used in evaluating the capabilif he Adverse soilsadjusted data to better differentiate
entries. Adjusting the original visual tolerancedrought resistance scores for field soil
GENETIC EVALUATION AND UTI LlZATION
moisture conditions increased the
ratio, decreased the CV, and
increased the capability of Duncans
Varietal tolerance for acid sulfate
soils in North Vietnam
Multiple Range Test (5% level) to differ- Dao The Tuan, plant physiologist, andentiate between entries (see table).
which are usually well known by the Vietnam
individual scorer to systematically cope
with the problem of inherent variability Varieties were screened for acid sulfate
in drought screening caused by non- soil tolerance during the 1977, 1978, and
This method uses check varietiesNguyen Huu Nghia, geneticist, Vietnam
Agricultural Science Institute, Hanoi,
s V2
sE2
(s V2 (sE2)
sV2/sE2
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1979 dry seasons at Haiphong, 100 km
east of Hanoi. Soils had pH 3.1-3.4 with
4.45-6.20 meq exchangeable aluminum
The 245 varieties and lines screened
were selected from among local germ-
plasm and 1RRl lines tolerant of salin-
ity, drought, iron (Fe) toxicity, and
phosphorus (P) deficiency. Iron toxicity
was evaluated on the Standard Evalua-
tion System for Rice scale 4 and 8 weeks
after transplanting.
Most tolerant of acid sulfate soils
were local varieties Bu, Pokkali, Cut,
Cuom, and Chim da. (Table 1). Most
tolerant lines were IR2151-96-1-5-3,
IR2 153-26-3-5-6, IR1529-680-3-2, and
(Al)/ 100 g.
B9C-Md-3-3.
Tolerance for Al and Fe toxicity and
P deficiency was tested among 15 varie-
ties and lines at Thanh t experiment
station. Al toxicity was determined by
soaking germinated seeds in 3 and
30 mg Al/ liter soil solution. Fe toxicity
and P deficiency tests were done in pots.
Local variety Ba was tolerant of all
three factors (Table 2). IR2151-96-1-5-2,
which was less tolerant in the field at 8
weeks, also was less tolerant of iron.
A close relationship was found
between Al toxicity and P deficiency
(correlation coefficient 0.747). Toleran-
ces for Al and Fe toxicity were notrelated (correlation coefficient 0.299).
One month after transplanting, with
soil pH 4.0 and Al in the soil solution at
7.8 mg/ liter, field evaluation scores
correlated with AI toxicity tolerance (r=
0.917). But 2 months after transplanting,
with soil pH 4.9. field evaluation scores
did not correlate with Fe toxicity toler-
ance (r = 0.376), probably because both
factors had some influence.
IR lines with IR1416-131-5, CR94-13,
and Indonesian variety Sigadis in their
parentage are tolerant of Fe toxicity. In
these studies, tolerance of Al toxicity
and P deficiency seemed to be related to
the presence of Sigadis genes. It appears
that acid soil tolerance is related to tol-
erance for Al toxicity, Fe toxicity, and
P deficiency.
Three varieties IR2 I5 1-96 1-5-3,
IR2153-26-3-56. and B9C-Md-3-3
were selected for yield trials in North
Vietnam. IR2 153 also can be cultivated
Table 1. Field scoresa of representative varieties and lines in varietal screening on acid sulfate soilsb
in North Vietnam.
Variety or line Score Variety or line Score
CSSR-1IR2058-78-1-3-2-3 (IR46)IR2061-464-24-46
IET5 2 3 3
BG94-1
IR1529-430-2IR2053-160-1-2-2IR2070-719-3-5IR2153-26-3-5-2IR2053-436-1-2KI49PokkaliM1-48IR28
IR2153-43-2-5-3
IR2071-586-5-6-34IR2153-26-3-5-6
IR2823-399-56IR4573-4-3-7-14IR4595-4-1-13IR4630-22-2-17
IR4763-73-1-11
IR1514A-E666IR2031-2384-1-3-2IR26IR2061-214-2-24-1IR1529-680-3-2IR994-102-2-3-2-2-2IR2151-190-3-5-5lR2151-96-1-5-3
5
558
67
563
74-52
894
52
6
668
75-63-46
62-3552
IR40 4IR42 5
312151-598-3-5-5 4IR2863-38-1 3-4
IR4227-
164-
1-
1 6lR4613-54-5 9B9C-Md-3-3 2-3IR1529-430-3 3IR1750-F5B-5 4-5IR2035-117-3 5IR2035-242-1 5
IR2061-522-6-9 7IR3839-1 4-5
IR3880-13 8
IR3880-17 4
IR9575 3IRATl3 3
C22 3C46-151IR242 4lR36 5-6A4 3
IR8 7386 (NN75-7) 7Bu 1cut 2Cuom 2424 (NN75-2) 5
Sai duong 4-5Chiem da 2B541-bkn-19-34 3
a 1980 Standard Evaluation System for Rice scale of 1-9: 1 = growth and tillering nearly normal, 9 =
almost all plants dead or dying. bMean of 3 dry seasons.
Table 2. Tolerancea for acid sulfate soils and other stresses of different varieties and lines in green-house tests in North Vietnam.
Variety or lineAcid sulfate soils tolerane a Al toxicity P deficiency Fe toxici
1 mo 2 mo tolerance tolerance tolerance
Bu 1 1 1 1 1-2
IR2151-96-1-5-2 1 2 1 1 3-4
IR2153-26-3-5-6 2 3 3 3 4A4 2 3 3 3 2-4B9C-Md-3-3 3 3 3 3 4
424 (NN75-2) 1 5 1 1 5
B541-bkn52-3-3 5 3 5 3 4-5
IR42 5 6 3 3 53-5
IR46 5 7 3 3 5
IR9575 7 5 5 3 3
IR1529-680-3-2 5 4 5 5
386 (NN75-7) 5 7 5 1 3
IR4683-54
-3-3-2 5 3 7
IR2797-105-2-2-3 5 3 7IR8 7 5 7 5 5
a 1980 Standard Evaluation System for Rice scale of 1-9: 1 = growth and tillering nearly normal; 5 =growth and tillering retarded, many leaves discolored; 9 = almost all plants dead or dying.
in saline soils. IR2 I5 I, with tolerance for
P deficiency and resistance to brown
planthopper biotype 1, also is accepted
in regions where IR8 cannot be
cultivated.
Individuals organiozations and media
who wish additional details of.
information presented in IRRN should
write directly to the authors.
IRRN 7:4 (August 1982) 1
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Pest management and control DISEASES
Relative humidity and nematode
number and survival in rice seeds
Nguyen-ti Thu Cuc and Le-Thanh Giang,
Plant Protection Department, University of
Cantho, Hau Giang, Vietnam
Seeds of rice varieties infested with
nematode D. angustus were collected in
Dong Thanp and Hau-Giang Province
(the Mekong Delta) and soaked in dis-
tilled water for 2 hours. Then, the husk
was separated from the albumen andseeds were resoaked for 1 hour.
Nematodes were found inside filled
and unfilled grains, between the tegmen
and albumen. They also can cling out-
side the tegmen.
Nematode populations in the seeds
varied with variety of rice. Two-day-old
seeds of local varieties Nep mua and
Lua Tieu with 16.5-17% relative humid-
ity were examined. In Lua Tieu, nema-
tode counts were 7 nematodes/ 100unfilled grains and 25/ 100 filled grains.
In Nep mua, nematode count was highe
63 nematodes/ 100 unfilled grains and
167/100 filled grains.
When infested seeds were dried in th
sun (44-45 C) for 4 days (6 hours/ day)
seed humidity decreased to below 12%
and nematodes were killed.
Fungicidal control of rice grain tine were tested for control of grain Fungicidal control of grain discoloration at
discoloration discoloration. Kannagi was the test Mettupalayam, India.variety. Application Discolor
Panicles at the milk stage were Fungicide rate graina
V. S. Duraisamy, agricultural officer, Train-
ing and Visit Programme, Mattupalayam sprayed with spore suspensions ofH.(%) (%)
641 301, India oryzae, T. padwickii, and C. lunata. Carbendazim 0.2 4.10.2 3.2
Yellow or brown discoloration of grain the fungicides. Percentage discolorationMancozeb 0.2 0.3
34% mancozeb 0.2 0.2
After 24 hours, they were sprayed with Baycar
is caused by fungi Helminthosporium was calculated at panicle maturity. IBP 0.2 0.3
oryzae, Trichoconis padwickii, and Cur- Application of 0.2% quazatine, IBP,Edifenphos 0.2 2.8
vularia lunata. Seven fungicides car- and mancozeb prevented discolorationQuazatine 0.2 0.2
Control 8.7
bendazim, Baycar, mancozeb, 34% in the field (see table). Baycar and car- CD (0.05) = 0.097
mancozeb, IBP, edifenphos, and quaza- bendazim were not effective. aMean of 3 replications.
Epidemiology of brown spot disease
of rice in Karnataka, India
S. Sannegowda and K. T. Pandurange-
gowda, Plant Pathology Department, Uni-
versity of Agricultural Sciences, Regional
Research Station, V. C. Farm, Mandya,
Karnataka, India
The development and spread of brown
spot disease were studied in the field and
the relationship between disease inci-
dence and weather factors wasexamined.
Binnybhog was sown monthly, from 1
January to 31 December 1980 at Man-
dya. Periodic observations of disease
development were made and daily max-
imum and minimum temperatures, rela-
tive humidity at 0730 hours and 1430
hours, rainfall, and sunshine were aver-
aged for each month.
Highly susceptible rice variety
14 IRRN 7:4 (August 1982)
Incidence of brown spot was 2.5% factors. October to December had max
from January to September, then sud- imum temperatures of 27-29 C and mi
denly increased to 45% during October, imum temperatures of 15-20 C, relativ
peaked at 50% in November, and humidity of 86-90 at 0730 hours and 58
dropped gradually to 40% in December 62 at 1430 hours, 0.2-2.6 mm rainfall,
(see table). The variability in disease and average daily sunshine of 7-9
incidence might be attributed to weather hours.
Weather factors and brown spot disease incidence at Mandya, Karnataka, India.
Brown spot Weather factors (av)
Month incidence Temperature (C) Relative humidity Rainfall Sunshine/d
(%)Max Min 0730 h 1430 h (mm) (h)
Jan 2 30 14 81 47 0 10Feb 3 31 19 85 41 0 12Mar 3 32 20 82 44 0 12
Apr 3 34 22 82 43 0 10
May 1 32 22 81 51 2.5 10
June 3 31 21 89 60 2.9 10Jul 5 29 20 86 62 2.7 8
Aug 5 28 20 89 66 4.4 6
Sep 5 28 20 91 65 11.0 8
Oct 45 29 20 90 60 2.6 7
Nov 50 2820 87 62 1.2 9Dec 40 27 15 86 58 0.2 8
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Root-knot disease of rice in the
Mekong Delta, Vietnam
Dang-ngoc Kinh, N. M. Huong, and N. V.Ut, Plant Protection Department, Universityof Cantho, Hau-Giang, Vietnam
Local and improved rice varieties have been found infested with root-knot
nematodes in the Mekong Delta. The
summer and winter crops using
improved varieties were more seriously
attacked than the main crop. Despite
galls in the root systems, the main crop
was seldom damaged, because it had
standing water in the field. Floating rice
varieties such as Nang-Tay also were
infested. The nematode on Nang-Tay
was identified by C. Germani as
Meloidogyne graminicola.
yield of rice variety TN 73-2 and
methods of control were done in thefield in Kien-Giang Province. At 30 days
after sowing, gall numbers averaged 13-
15/plant. The nematode decreased plant
height by about 3 148% and rice yield
by about 65%.
tion of carbofuran and diazinon in irri-
Two studies of damage to height and
Either continuous flooding or applica-
gation water was highly effective con-
trol, increasing yield 100-160% over that
in the untreated plots and 70-90% over
that in the nondiseased plots. Both
chemicals gave good control at 10 and
20 kg commercial product/ha to 20 days
after treatment. Then, gall numbers
began to increase but did not causedamage. Continuous flooding gave
slower results, but the longer the flood-
ing, the fewer the number of galls.
Flooding the field with tidewater was
not effective. Neither control method
had much effect at booting.
Field soil as a source of rice stem
nematodes
Nguyen-thi Thu Cuc, Plant ProtectionDepartment, University of Cantho, Hau-Giang, Vietnam
The Baermann-funnel extraction
method was used to determine the pres-
ence of rice stem nematode Ditylenchus
angustus in submerged field soil in the
infested rice-producing region of An-
Giang and Hau-Giang Provinces.Infested soil contained 8-12 living nema-
todes in 90 ml of soil at the 0-20 cm
depth and 3-7 nematodes at 204 cm
depth.
D. angustus was not observed in soil
samples dried for 1.5 months. Dried
infested soil was used to grow rice plants
in the greenhouse. Disease symptoms
were recorded 2 months after transplant-ing. Infected seedlings were 14.2% to
18.1% in dry soil from the 0-20 cm
depth and 12.1% to 14.4% in dry soil
from the 20-40 cm depth.
Pest management and control INSECTS
Parasites of the rice slug caterpillar
P. B. Chatterjee, entomologist, All IndiaCoordinated Rice Improvement Project,
Chinsurah R. S. 712102, West Bengal, India
A slug caterpillar, Latoia (Parasa) bico-
lor Walker (Lepidoptera: Limacodidae),
regularly appears on rice in Coochbehar,
Jalpaiguri, and in the plains of Darjeel-
ing near the foothills of the sub-
Himalayan ranges. The spined caterpil-
lars cause extensive foliar damage from
July to October, often necessitating
retransplanting. Grubs cause severedermal itching and urticaria on touch.
The arthropod enemies of L. bicolor
are two hymenopterous parasitoids:
Brachymeria euploeae Westwood (Chal-
cidoidea: Chalcididae) and Goryphus
busilaris Holmgren [Ichneumonoidea:
Ichneumonidae]. They parasitize 24%
of the pest's pupae in the field. In gen-
eral, third and fourth generations ofL.
bicolor are more parasitized.
Sepedon sphegeus (Fabr.)
(Sciomyzidae) and Notiphila spp.
(Ephydridae ): alternate hosts of
Trichogramma japonicum Ashmead,
a rice stem borer egg parasite
Alberto T. Barrion, research assistant, and
James A. Litsinger, entomologist, Entomol-
ogy Department, International Rice
Research Institute
In the Philippines, Trichogramma
japonicum Ashmead is a common egg
parasite of rice stem borers Scirpophaga
incertulas, Chilo suppressalis, and C.
polychrysus. Eggs of two genera of
flies that inhabit rice fields Sepedon
sphegeus (Fabr.) (Sciomyzidae) and
Notiphila latigenis Hendel, N. similis
Meijere and N. spinosa Cresson (Ephy-
dridae) were collected in the field in
Incidence of parasitization by Trichogramma japonicum on eggs of Sepedon sphegeus andNotiphilaspp. collected from 6 fields in the Philippines, 1981-82.
Sepedon sphegeus Notiphila spp.a
held zation held zationProvince Municipality Sampling date Eggs Parasiti- Eggs Parasiti
(no.) (%) (no.) (%)
CagayanLaguna
Agusan del SurBukidnon
North CotabatoZamboanga del Sur
SolanaLos Baos
Del MonteKalilanganKabacanPagadian
23 Sep 1981
7-17 Dec 198118-29 Jan 19828-24 Feb 1982
26 Jul 198129 Jul l9814-6 Jan 19823-4 Aug 1981
23-27 Nov 19816
11
518240
006
036.4
20.0
5.58.3
0
1452
181162234
24
362218
14.3
8.02.07.4
10.306.05.0
a Notiphila latigenisHendel, N. similis Meijere, and N. spinosa Cresson.
IRRN 7:4 (August 1982) 15
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1981-82 in six provinces. T. japonicum encounter both. Even though fly eggs two fly genera would maintain Tricho-occurred in at least one fly species (see are much larger than stem borer eggs, gramma in the field at times of low stemtable). they are acceptable to the wasps. borer populations, enhancing its effec-
Sepedon and Notiphila lay egg masses Low rates of parasitization in fly eggs tiveness as a natural enemy of stem
on rice leaves in a similar manner as the indicate that stem borer eggs are pre- borers.
rice stem borer. Trichogramma wasps ferred. But such alternate hosts as these
Populations of gall midge, white-
backed planthopper, and thrips on
Pragati paddy
S. K. Shrivastava, C. L. Patidar, B. C.
Shukla, D. J. Pophaly, U. K. Kaushik, P. D.
Deshmukh, and G. A. Gangrade, Zonal
Agricultural Research Station (ZARS),
Agriculture College, Raipur, Madhya Pra-
desh, India
Pragati paddy was transplanted on 25
August 1979 at the ZARS Labhandi
Farm, Raipur. Three sets of 50 hillseach were monitored at intervals of 1, 4,
and 7 days beginning 1 day after trans-
planting (DT), for gall midge, white-
backed planthopper, and thrips infesta-
tion. Another 100 hills were treated with
malathion 50 EC 0.05% on 9 and 24
September, 16 October, and 3
November 1979, and monitored.
In untreated hills, gall midge infesta-
tion started on 10 September (16 DT).
Beginning 17 September, there was a
sudden increase in silvershoot develop-
ment, peaking 25 September (30 DT). In
treated hills, silvershoot development
also peaked 25 September, then declined
(see figure).
Whitebacked planthopper popula-
tions on untreated hills began to in-
crease on 11 September (17 DT), peaked
on 10 October (45 DT), then declined
sharply. In treated hills, the increase was
the same as in untreated plants, but
populations declined temporarily after
each spraying, then increased again but
did not attain the level of untreated hills.
By 14 November, populations were very
low.
Thrip populations were heavy up to
10 September (16 DT) on untreated
plants, then declined to near zero on 10
October (45 DT). After 31 October (62
DT), populations again increased
rapidly, peaking on 7 November (69
DT). In treated plants, populations were
negligible.
16 IRRN 7:4 (August 1982)
Populations of silvershoots,whitebacked planthoppers (WBPH),and thrips on transplanted Pragati
paddy, with or without malathion50 EC 0.05%. Madhya Pradesh,India.
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Table 2. Population buildup of whitebacked planthopper on N22 rice variety grown with differentlevels of SiO2 at IRRI.
a
SiO2 (ppm) Leaves Mortality25 DAI
in culturesolution 5 DAI (no.) (no.) (no.)
(no.)(%) Nymphs Males Females
Total
0 1.2 a50 4.2 b
100 4.4 b150 4.4 b
16.0 a36.0 a
24.0 a28.0 a
188.2 a100.6 ab
91.8 b
61.4 b
35.6 c42.4 bc
52.6 ab
53.8 a
25.4 a21.8 b
17.4 c
18.2 c
249.2 a
164.8 ab
167.8 abc133.4 bc
aAv of 5 replications. Separation of means in a column under each level by Duncans multiple range
test at the 5% level. DAI = days after infestation.
Survival of whitebacked planthopper
(WBPH) nymphs on rice seedlings
growing in culture solution with three
silica (SiO2) levels was examined.
from 5.5 to 6.0. Each silica level was
replicated five times.
When plants were 15 and 30 days old,
10 first-instar nymphs were introduced
in each cage.
On plants treated with silica, very few
nymphs developed into adults (Table 1).At 15 days after infestation, the highest
number of adults was recorded on
plants with no silica.
For population buildup counts, 5
pairs of 3- to 5-day-old WBPH adults
were introduced in each cage. Surviving
adults were counted 5 days after caging.
Progeny were counted when plants were
35 days old.
The number of nymphs was highest at
0 ppm SiO2 and lowest at 150 ppm
(Table 2). The number of malesincreased as silica concentration
increased.
Apparently SiO2 induces development
of males but inhibits feeding of
WBPH.
Effects of silica level on whitebacked
planthopper
Hong-Sun Kim, research scholar, and
E, A. Heinrichs, entomologist and depart-
ment head, Entomology Department, Inter-
national Rice Research Institute
Table 1. Effect of silica on survival of whitebacked planthoppersa at IRRI.
SiO2 (ppm)in culture
Av no.
leaves/plantsolution
Surviving whitebacked planthoppers b (no.)
10 DAI 15 DAI 20 DAI 25 DAI
N A N A N A N A
0 6.8 a 8.6 a 1.4 a 5.4 a 4.2 a 0.0 b 9.2 a 0.0 a 9.2 a 53.0 a
50 5.2 b 8.0 a 0.2 b 5.4 a 2.2 b 0.0 b 7.0 b 0.0 a 7.0 b 0.0 b
100 4.2 b 6.6 b 0.0 b 5.0 a 1.8 b 0.4 ab 5.8 c 0.0 a 6.2 b 0.0 b150 4.2 b 6.4 b 0.0 b 4.6 a 1.2 b 0.8 a 5.0 c 0.0 a 5.8 b 0.0 b
a Av of 5 replications. Separation of means in a column and under each level by Duncans multiple range test at the 5% level. bDAI = days after infestation
N = nymphs, A = adults, NG = new generation.
One 10-day-old seedling of variety
N22 (Wbph 1 gene for resistance to
WBPH) was transplanted to each pot
containing a culture solution. Each pot
was put in a cage. A 60-liter culture
solution contained 100 ml N, 100 ml P,
100 ml K, 100 ml Ca, 100 ml Mg, 10 ml
microelements, 60 ml Fe EDTA.
Graded levels of silica as sodium meta-
silicate (Na2SiO35H2) were added to the
culture solution and the pH adjusted
Disruption of striped rice borer
males orientation to pheromone
traps
J. O. Lee, H. G. Goh, Y. H. Kim, and
J. S. Park, entomologists, Institute of Agri-
cultural Sciences, ORD; and J. H. Kim and
C. H. Park, scientists, KAIST, Korea
Disruption of male striped rice borer
(Chilo suppressalis) orientation to moni-
toring traps by a single spray application
of pheromone was investigated in paddy
fields in 1981. Microencapsulated
pheromone formulation as a mixture of
(z)-11-hexadecenal and (z)-13-
octadecenal at 4.5:1 was prepared by
urea (1) formalin (2) copolymerization,
mixed with a spreader, and sprayed at
10 mg and 30 mg on weeds of paddy
Disruption by microencapsulated pheromone of male striped borer moth orientation to monitoringhap. a Korea, 1981.
Time after pheromoneMales trapped (no.)
application 10 mg 30 mgb
(days) Treated Not Treated Nottreated
Treated Not
Before treatment
12
34
5
6
789
10
11121314
Total trapped
50
0
101
0
0
1110000
5
194
1
100
1
0
0110102
12
9 11 23 190 2 0 60 1 0 8
0 2 0 60 1 0 100 1 0 70 1 0 2
0 1 0 3
0 2 0 10 2 0 20 0 1 43 4 1 02 2 0 13 3 3 3
10 25 5 57
2 3 0 4
aTrap baited with 100 g pheromone as the attractant source. b30 mg applications in two differentareas.
IRRN 7:4 (August 1982) 17
treated treated
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bank around a monitoring trap contain- from 10 days before application to 15 30 mg for 7-10 days (see table). Theing 100 g attractant. days after. The ability of male moths to pheromone had lost much of its disrup
Males caught were counted daily locate the trap source was suppressed at
Soil and crop management
Nitrogen management in flooded
rice
B. Mishra and R. D. Sharma, Soil Science
Department, G. B. Pant University of Agri-
culture and Technology, Pantnagar 263145
India
A field experiment on flooded rice in the
1981 monsoon season evaluated urea
briquet placement (5 cm below soil sur-
face), margosa seedcake-coated urea,
shellac-coated urea, sulfur-coated urea,
farmyard manure (FYM) + urea, and
urea split application. Experimental field
soil was silty clay loam (Mollisol). Each
nitrogen source was applied at 60 kg
N/ha.
There was no yield advantage in 3
split applications of urea over 2 splits at
60 kg N/ha (see table). Margosa
seedcake-coated urea and shellac-coated
urea also did not offer any significant
improvement in yield over urea appliedin three split doses. Urea + FYM was
equal to urea alone (3 splits).
Sulfur-coated urea produced signifi-
cantly higher yields than did ordinary
urea applied in three split doses. Urea
briquet placement 1 week after trans-
Algae in rice fields of Chingleput
District, Tamil Nadu, India
J. Venkatakrishnan and K. Narayanan,
Paddy Experiment Station, Tirur - 602 025,
Tamil Nadu, India
Samples of algae were collected during
October and November 1981 (monsoon
season). Rainfall during the period was
370.9 mm, maximum temperature range
was 39.0-25.5 C, and minimum
temperature range was 24.5-16.5 C.
Standing water of 1-2 cm was main-
tained in the fields by lift irrigation from
an open well.
18 IRRN 7:4 (August 1982)
Yield of rough rice at 60 kg N/ha.a
Nitrogen source Method and time of applicationGrain yield
N useefficiency(t/ha)
(kg grain/kg N
NoneUrea Broadcast, 3 splitsUrea Broadcast, 2 splits (transplanting and
Urea
Urea briquet Placement at 5 cm, 1 wk after trans-
Urea briquet Placement at 5 cm, 3 wk after trans-
Margosa seedcake- Broadcast at transplanting
Margosa seedcake- Broadcast 2 splits (transplanting and
Shellac-coated urea Broadcast at transplantingSulfur-coated urea Broadcast at transplantingFYM + urea
(30 + 30)Broadcast and mixed in soil before
FYM + ureatransplanting
FYM mixed with soil before transplanting(30 + 30) and urea broadcast 3 wk after trans-
tiller initiation)
panicle initiation)Broadcast, 2 splits (tiller initiation and
planting
planting
coated urea
coated urea tiller initiation)
planting
S.Em C.D. 5%
aFYM = farmyard manure.
3.323.98 114.21 15
4.24 15
4.85 25
5.37 34
3.98 11
3.81 8
4.24 154.43 183.64 5
3.99 11
0.15 0.45
planting was also significantly superior The highest yield was with urea brique
to ordinary urea (2 or 3 splits), but gave placement 3 weeks after transplanting
lower yields than placement 3 weeks Nitrogen use efficiency with urea bri
after transplanting probably because quet was more than 2 times as high as
of the relatively long growth period (144 2 or 3 split applications of ordinary
days) of the rice variety (Jaya) grown. urea.
Abundance of nitrogen-fixiing algae (Cyanophyta Effect of seedling age on susceptibspecies). Tamil Nadu, India.
Species
ity to aluminum toxicityRelative
abundancea
Gloeocapsa decorticans x Mai Van Quyen and S. Yoshida, Interna-
Anabaena oryzae xx tional Rice Research InstituteCylindrospermum muscicola x
Nostoc sphaericum x Aulosira prolifica x Although aluminum toxicity is rarely a
Calothrix sp. problem in wetland rice, it may impair
ax = rare, xx = moderate. growth even in flooded soils when soil
pH remains low because of strong acid-
Species of algae identified consisted of ity and low microbial activity. Relative
11 Cyanophyta, 6 Chlorophyta, 2 young seedlings may fail to establish on
Euglenophyta, and 5 Bacillariophyta. Of some acid sulfate soils.
the 11 Cyanophyta species, 6 are known Solution culture technique was used
to be nitrogen-fixing algae (see table). to examine the effect of seedling age on
tive effect 10 days after application.
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susceptibility to aluminum toxicity. Two
varieties (IR26 and IR36), 3 plant ages
(10-, 20-, and 30-day-old seedlings), and
3 aluminum concentrations (0, 30, and
60 ppm) were used. At a specified plant
age, seedlings were transferred to a plas-
tic tray containing culture solution and
different levels of aluminum. They were
grown for 14 days in a glasshouse room
maintained at 29/21 C (day/night)
with natural light and 70% relative
humidity.
IR26 and IR36 showed a similar
trend. A larger difference was found in
shoot weight than in root weight (see
table). Stunted growth in 10-day-old
seedlings was noticed at 60 ppm Al.
Comparison of zinc sulfate and
Zn-EDTA as foliar spray
P. C. Srivastava, R. S. Sachan, and
M. S. Gangwar, Soil Science Department,
G. B. Pant University of Agriculture and
TechnoIogy, Pantnagar-263145, India
Chelated formulations of zinc (particu-
larly Zn-EDTA) have been recom-
mended as foliar spray. The absorption
efficiencies of Zn-EDTA and conven-
tional ZnSO4 + lime spray were com-
pared in a pot experiment.
A silty clay loam soil containing
1.30 ppm DTPA extractable Zn was
used at 2 kg/pot. Two 20-day-old Jaya
seedlings in each of 20 pots were
sprayed with one of 5 Zn treatments 15
days after transplanting. Treatments,
replicated 4 times, were: control (no Zn);
100 ppm Zn as 0.044% ZnSO4 + 0.022%
lime spray; 100 ppm Zn as chelated Zn
(manufacturers recommended rate);
1,130 ppm Zn as 0.5 ZnSO4 + 0.25%
lime (recommended spray), and
1,130 ppm Zn as chelated zinc(Sukshmin-Z).
Both ZnSO4 and chelated Zn foliar
spray increased dry matter and Zn
uptake over the control (Fig. 1). Yield
with 100 ppm chelated Zn was 37%
higher than the control. Dry matter
yield and Zn uptake did not differ signifi-
cantly with 100 ppm and 1,130 ppm Zn
as ZnSO4, nor with 100 ppm and 1,130
ppm chelated Zn.
Effect of seedling age and aluminum concentration on average root and shoot weights of 2 rice varie
ties grown in culture solution at IRRI.a
Seedling age Al addedRoot weight Shoot weight
(days) (ppm) mg/plant % of check mg/plant % of chec
10 0 83 100 266 100
30 69 83 171 64
60 62 74 132 49
20 0 298 100 908 10030 272 91 878 96
60 238 79 830 91
30 0 677 100 2143 10030 544 80 2032 94
60 499 73 2159 100
a
Figures are mean values of IR26 and IR36.
These results indicate that, in soils old) seedlings is not advisable. Twenty-
where aluminum toxicity is a potential day-old or even older seedlings would
problem, planting dapog (about 11 days minimize risk of stand failure.
1. Effect of zinc foliarsprays on rice dry matteryield and zinc uptake.
2. Effect of zincfoliar sprays onrice uptake ofcopper, iron, andmanganese.
IRRN 7:4 (August 1982) 1
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