Abstract:
Investigation for alternative source of cytoplasmic male sterility suitable
for warm humid tropical climatic conditions was conducted at Agricultural
Research Station, Mannuthy and College of Horticulture, Vellanikkara (1998••
2001). The study included the evolution of alternative source of cytoplasmic male
sterility, potential CMS lines, screening of genotypes for fertility restoration and its
genetic analysis. From the backcross experiments conducted, sterile cytoplasmic
source was confirmed to be that of Bhadra and saline tolerant rice variety Vytila-3.
The cytoplasmic nuclear interaction exhibited by various crosses studied, resulted
in the manifestation of male sterility. The four cross combinations with Vytila-3
and Bhadra as cytoplasmic maternal sources exhibited increase in male sterility
with each step of backcross. In the case of Vytila-3 x IR 36, 100 percentage male
sterility was obtained in the F2BC3 generation. This points out the relevance of
backcrossing to evolve fully male sterile line in other crosses also. With respect to
grain yield and components, the highest positive gca effect was observed in Bhadra
followed by Mattatriveni. Since the dominance variance of this character was
greater than the additive genetic variance, there is scope for hybrid vigour
exploitation. The estimation of heterosis in the case of hybrids produced was
significant enough to explore the prospects of hybrid rice suited to warm humid
tropics. Generation mean analysis revealed that the characters tillers at harvest,
panicle length, spikelets per panicle, grain LIB ratio and pollen sterility percentage
were controlled by both allelic contribution and its interactive effects and hence for
improving the characters, hybridization followed by selection can be resorted to.
