HETEROSIS, COMBINING ABILITY AND GENE ACTION STUDIES IN TGMS BASED RICE HYBRIDS UNDER NORMAL AND SALT AFFECTED ENVIRONMENTS

Five TGMS lines, eight salt tolerant testers and 40 hybrids obtained by crossing in line x tester
design were evaluated for their genetic worth and salinity tolerance in normal and salt affected
environments for 12 characters viz., days to 50 per cent flowering, plant height, productive tillers per
plant, panicle exsertion, panicle length, panicle weight, filled grains per panicle, spikelet fertility, 100
grain weight, Na+ : K+ ratio, harvest index and grain yield per plant. The parents GD 98028, GD 98029,
GD 98168 and Vytilla 3 produced good combiners for salt tolerance and grain yield per plant. The
tester CO 43 showed good mean and gca effects in all environments for the trait grain yield per plant,
while CSR 10 and Vytilla 3 recorded good mean and gca effects for Na+ : K+ ratio in salt affected
environments. Hybrids GD 98028/Nona Bokra, GD 98028/Vytilla 3, GD 98021/CSR 10 and GD
98021/CO 43 recorded high sca effects in all the environments for most of the traits under study. The
hybrid GD 98179/CSSRI 60 recorded the highest standard heterosis per cent for the trait grain yield
per plant in all the environments followed by GD 98168/Vytilla 3, GD 98029/CSSRI 60, GD 98029/
CSR 23 and GD 98028/ Nona Bokra. In salt affected environments the hybrids GD 98028/CSR 23 and
GD 98021/CO 43 recorded high heterosis for both Na+ : K+ ratio and grain yield per plant. Hybrids GD
98028/CSR 23, GD 98028/CO 43 and GD 98021/CO 43 can be exploited for improving salt tolerance
and yield by heterosis breeding. All the characters were found to be controlled by dominance gene
action except for plant height under pooled condition alone.