Central Rice Research Institute Annual report...2011-12

Breeding for Resistance/Tolerance to Biotic, Abiotic and Environmental Stresses
Kankana, Erasama, a costal saline area along with the
check varieties SR26B and IR29. The scoring against
salinity stress was done at vegetative stage and also at
maturity and observations were recorded on plant
height, panicle length, panicle bearing tillers and spikelet
fertility (%). Panicles from single plants were collected.
The same set were also grown at CRRI under
normal conditions. Out of eight hundred twenty five,
452 lines showed stress scoring of 3-5 and 239 lines
showed > 70 % fertility as well as stress score of 3-5,
thus demonstrating the wide variability for this trait in
the germplasm studied.
Forty two lines along with check varieties were directly
sown in salinity screening tank at CRRI. These
lines were exposed to salt stress from 21 day seedling
stage to flowering. Salinity stress scoring was done at
vegetative stage according to IRRI guidelines and also
15 qualitative character data were taken according to
descriptors for rice (IRRI, 1980). After harvesting total
germplasm, fertility percentage of the surviving lines
was calculated. Twelve out of the 42 lines evaluated
were found to have more than 70 per cent fertility and
stress scoring of 3-5.
Genotyping was done with fifty rice accessions
through PCR analysis using gene specific and also
microsatellite markers such as AP3206, AP3206f, SKC1,
SKC1b, SKC2a, SKC10, RM3412, RM10745, RM10748,
Pect4, RM493, RM10793, Salt1, RM8094, and RM562
for the prospecting of genes that confer tolerance to salt
stress. Polymorphism was observed with some of the
markers like AP3206, AP3206f, Pect4, RM3412, SKC2a,
SKC10, RM10745, RM10748, RM10793, RM493,
RM8094 and Salt1.
Phenotyping for submergence tolerance
Thirteen rice genotypes including highly tolerant
variety FR13A and susceptible variety IR42, FR13B,
FR43B, Sabita, AC38575, Atiranga, Kusuma,
Gangasiuli, Kalaputia, CR780, Khoda and IR64-Sub1
were evaluated for the identification of submergence
tolerance. Molecular analysis of these thirteen genotypes
with allele specific and intragenic marker in Sub1
locus, along with RM219, along with PDC and gene
specific markers for submergence tolerance was carried
out. Out of the all primers, Sub1BC2, Sub1BC3,
SubLCI73 and RM219 showed clear polymorphism.
Phenotyping under drought stress
Two thousand and seven hundred accessions were
direct seeded in the experimental farm of CRRI at
Santhapur during the wet season and were subjected
to severe drought stress starting from 30 day old crop.
The results indicated that 270 accessions were identified
as promising based on drought scoring and morphological
symptoms.
Seventy eight rice accessions were screened at vegetative
stage under field condition along with two
drought tolerant checks Vandana and CR143-2-2 and
one drought susceptible check IR20. The drought scores
recorded as per IRRI SES scoring in 1 to 9 scales. Results
indicated that, from the total lines, 30 lines were
identified as best vegetative stage drought tolerant lines
with early recovery by SES score ‘0’ and ‘1’, out of which
12 entries recorded SES score ‘0’ and 18 entries recorded
SES score ‘1’ compared to the tolerant and susceptible
checks. The same set of genotypes was evaluated under
artificial conditions in the lab. The germination rates
using five day old seedling were tested under Poly Ethylene
Glycol 6000 mediated moisture stress. Higher
degree of correlation was observed between the results
of the field screening and the PEG experiments with
eight genotypes being common to both PEG and field
evaluation.
Phenotyping under heat stress
Seven hundred genotypes were screened under
transplanted field conditions using staggered sowings
(early, normal and delayed sowing) for high temperature
tolerance to identify donor genotype(s). From heat
tolerance screening trials of germplasm during dry season
of 2011, three genotypes found highly tolerant to
heat stress with SES score 1 were AC39843, AC39834
and AC39969 with more than 80% spikelet fertility that
were at par /better than check Annapurna and N 22.
Mapping population of Naveen/Annapurna and
Shatabdi/Annapurna, Shatabdi/N 22 and Lalat/N22
are in F 4
/F 5
generation by SSD method. Few others genotypes
showing moderate degree of tolerance are
AC39975, AC11069, AC10925 and AC39935 showed
moderately resistance with more than 75% spikelet fertility.
The most susceptible genotypes was AC39880
with 56% fertility.
Identification of QTLs for Yield and Major
Biotic and Abiotic Stresses
Identification of QTLs for yield and BPH
resistance
The mapping populations (F 4
and F 5
) from different
crosses were developed for identification of QTLs associated
with yield and BPH resistance (Dhobanambari/
TN1) during wet season, 2011. Parental polymorphism
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