4.3.4 Gene action on F
2
population in normal condition
Evidence of bacterial leaf blight in the plant caused problem in grain filling so that many grains were unfilled. Number of filled grain in F2 population was
ranged 13-165 with an average of 49. Skewness test was not significantly different with zero indicating the filled grain number was controlled by additive-dominant
gene. Kurtosis test showed that several genes control the number of filled grain. In contrast, the number of unfilled grain increased due to the bacterial leaf blight
infection. Number of unfilled grain was ranged 32-159 with an average of 89. The t test value of skewness and kurtosis for number of filled grain were not
significantly different from zero indicates that the trait controlled polygenic with additive gene action.
Figure 4.5 Distribution of filled grains number in F2 rice population from IR 42 x IRRI 119 crossing under normal condition
Figure 4.6 Distribution of unfilled grains number in F2 rice population from IR 42 x IRRI 119 crossing under normal condition
Number of filled grain F
re q
u e
n cy
150 120
90 60
30 70
60 50
40 30
20 10
Number of unfilled grain F
re q
u e
n cy
162 144
126 108
90 72
54 36
40 30
20 10
IR 42
IRRI 119
Mean : 48.70
SE : 1.16
StDev : 20.0
Variance : 400.0
CV : 41.08
Min : 13
Max : 165
Skewness : 1.11
ns
Kurtosis : 3.35
P1 IR 42 : 39
P2 IRRI 119 : 37
IRRI 119
IR 42
Mean : 89.12
SE : 1.30
StDev : 22.22
Variance : 493.62
CV : 24.93
Min : 32
Max : 159
Skewness : 0.60
ns
Kurtosis : 0.33
tn
P1 IR 42 : 65.50
P2 IRRI 119 : 72.75
4.3.5 Stress Tolerance Index among Generation
The plant height of all generation was increased from normal condition to stagnant flooding stress. It was indicating that all generation response to water
increasing by stem elongation. Number of productive tiller and grain yield also were decreased from normal to stagnant flooding condition in all generations. Response
of panicle length and weight of 100 grain were varied among the generations.
The STI of F1 was higher than superior parent indicating the presence of over dominant gene action in plant height, panicle length, and grain weight per
plant. Meanwhile, the STI of F1 was higher than mid-parent indicating heterotic in number of productive tiller and weight of 100 grain.
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