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Rice Genomics and Genetics 2013, Vol.4, No.3, 9
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variety adaptable to rainfed upland with high yielding
potential coupled with good quality attributes. Such
variety must be superior to traditional land race
under farmer management skill (Verulkar et al., 2010).
Evidently, there is enough variability in the cultivated
rice gene pool and it wild relative (Lafitte et al.,
2006; Jongdee et al., 2006; Liu et al., 2004) to work
with in any breeding programme. Plant breeder has
a duty of selection for drought tolerant breeding
materials for crop improvement programme. The
focus of this study was to identify superior and
promising drought tolerant rice genotypes for rice
farmers in rainfed ecosystem that can be easily
spread through farmer-to-farmer seed exchange.
2 Material and Methods
The investigation was carried out at Agricultural
Research Station of University of Agricultural
Sciences Dharwad. The Research Station is located
at Mugad latitude of 15
o
15'North and longitude of
70
o
40' East and altitude of 695 meters above Mean
Sea Level (MSL) belonging to Agro-climatic zone
No.8 of Karnataka. The average rainfall of the Res-
earch Station is 101 6.20 mm in 75 rainy days distr-
ibuted mainly during kharif (June to October) season.
Breeding material for this study was a backcross
population (BC
1
F
6
) developed in India by Barwale
Foundation in Hyderabad using WAB-450, an
inter-specific derivative as donor and Swarna, a
mega rice variety in India, as recurrent parent. 188
BILs along with 10 checks transplanted in 12' pots
were screened inside rain out shelter (poly house)
for physiological traits during summer 2011 while
evaluation for productivity related traits was carried
out during kharif 2012 in the field. Three weeks old
seedlings were transplanted one seedling per pot in
randomized block design in two replications each
for two treatments (non-stress and water-stress). In
the water-stressed experiment (water-stressed treat-
ment), moisture stress was imposed by withholding
irrigation until severe leaf rolling was observed
from the onset of the reproductive growth phase till
grain filling stage; in control (non-stressed treatment)
experiment was daily irrigation until crop maturity.
Recommended agronomic practices were duly
followed for raising a good and healthy crop using
Package of practices for Paddy developed by UAS
Dharwad. Data was taken and analysed using
simple ANOVA to determine the mean performance
of the BILs and parents for physiological and
productivity traits.
3 Results and Discussion
The ANOVA in respect of all the characters studied
in BILs showed highly significant MSS for
genotypes indicating wide genetic differences for all
physiological and productivity traits (Table 1).
Heritability of most of the traits studied range from
moderate to high in the stressed and non-stressed
treatment. Heritability of traits like leaf temperature
and number of tiller showed a clear difference
between water-stress and non-stress treatment
(Table 2); this may be due to effect of environment
on the BILs.
Table 1 ANOVA for physiological and productivity related traits under stressed and unstressed condition in pot experiment
Trait
GMSS
EMSS
Stressed
Non-stressed
Stressed
Non-stressed
Relative water content (%)
106.01**
108.741**
4.21057
5.41804
Chlorophyll content (SPAD reading)
18.0051**
11.8463**
1.43503
1.14573
Leaf temperature (
℃
)
3.51058**
1.45025**
0.307205
0.208316
Leaf area (cm
2
)
9.5047**
8.3272**
0.486857
0.480438
Plant height (cm)
66.2819**
66.5549**
4.92112
4.43087
Number of tillers
20.7932**
33.5801**
4.27638
2.06733
Number of productive tillers
13.2216**
14.821**
2.51808
3.06421
Gain number per plant
131310**
156003**
13347.6
32884.5
Grain weight per plant (g)
9.0756**
13.0255**
1.52833
2.67133
Spikelet fertility (%)
15.3037**
7.28451**
2.28714
0.911155
Harvest index (%)
2.84665**
3.43925**
0.749992
0.792583
Note: ** - Significant at 0.01 probability