Basic HTML Version
Rice Genomics and Genetics 2013, Vol.4, No.3, 9
-
13
http://rgg.sophiapublisher.com
11
Table 2 Genetic parameters for physiological and productivity related traits under stressed and unstressed condition in pot experiment
Trait
PCV
GCV
MEAN
h²
GA
A
B
A
B
A
B
A
B
A
B
Relative water
content (%)
13.544 12.23696 13.01661 11.64171 54.81 61.74 92.35974 90.50791
25.76953 22.81536
Chlorophyll content
(SPAD reading)
7.0719 7.5819598 6.418059
6.999936 36.04 41.12 85.23642 82.36257
11.99875 13.31294
Leaf T(
℃
)
5.0983 3.90167 4.670029
3.376241 27.1
23.34 83.90664 74.87999
8.812213 6.018434
Leaf area (cm
2
)
14.411 11.619755 13.69066 10.96762 15.51 18.06 90.25463 89.09042
26.79332 21.3253
Plant height (cm)
7.9376 7.2635827 7.368615 6.795087 75.17 82.02 86.17722 87.51617
14.09124 13.09503
Number of tillers
21.814 23.731389 17.70638 22.31271 16.23 17.79 65.88391 88.40124
29.60647 43.21642
Number of
productive tillers
27.831 22.184116 22.95027 17.9862 10.08 13.48 68.00342 65.7347
38.98705 30.04029
Gain number per
plant
37.927 24.565709 34.24911 19.83304 709.1 1251 81.54594 65.18086
63.71148 32.98501
Grain weight per
plant (g)
27.533 20.448922 23.22832 16.60818 8.363 13.7
71.17427 65.96345
40.36887 27.78696
Spikelet fertility (%) 3.4309 2.1891536 2.951334 1.930493 86.44 92.47 73.99624 77.76495
5.229864 3.506932
Harvest index (%)
3.5599 3.4186111 2.718023
2.703554 37.67 42.55 58.29488 62.54186
4.274995 4.40441
Note: A:
Stressed; B: Non-stressed
Performance of BILs was generally lower under
water stressed treatment than non-stressed treatment
for all the traits studied except leaf temperature
which was higher under water stressed condition.
Reaction of plant to water stress is complex, it
involves physiological, morphological and bioche-
mical changes within the plant tissue. The initial
responses to drought stress occur at the leaf level in
response to stimuli generated in the leaf itself or
elsewhere in the plant and they have a negative
influence on carbon assimilation and growth (Chaves
et al., 2002). The combine effect of various reactions
within the plant tissues culminate in the actual
behaviour of plant to drought stress (Pereira and
Chaves, 1993).
Physiological and productivity performance of
donor parent (WAB-450) under water stress are
better than that of recurrent parent (Swarna) as
indicated by the percentage reduction (Table 3).
Except for traits like leaf area and plant height,
percentage reduction in performance of BILs for
physiological and productivity component traits when
subjected to water stress treatment were generally
lower than the recurrent parent Swarna. This can be
interpreted to imply that drought tolerant traits from
WAB-450 have been introgressed into Swarna
background. WAB-450 is known to be superior in
earliness, weed competetiveness, drought tolerance,
pest or disease resistance and other grain quality
attributes with yield advantage over
O. glaberrima
and
O. sativa
its parents (Africa Rice, 2011). The
introgression of
WAB-450
genome in mega variety
like Swarna background could impart earliness,
stress tolerance and productivity related traits.
Top 20 superior BILs (Table 4) that showed lowest
percentage reduction in important component traits
like relative water content, chlorophyll content, leaf
temperature and leaf area under water stress will be
suitable as breeding material for drought tolerance.
It has been reported that under conditions of water
stress, plants are often subjected to a high
temperature, which increases their vulnerability to
light stress and consequently the photo inhibition
(Shahenshah et al., 2010). When carbon dioxide
fixation is limited, the rate of active oxygen
formation increases in chloroplasts as excess
excitation energy, which would either become
manifest as oxidative damages to the plant or would
result in activation of defence and repair
mechanisms which could prevent such damage from
occurring (Shahenshah et.al., 2010). The decrease in
chlorophyll content under drought stress has been