Alternative sources of cytoplasmic male sterility and genetic analysis of fertility restoration in Rice (oryza Sativa L.)

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.