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Item Tiller emergence in rice and mutation frequency in the different ear categories(Kerala Agricultural University, 1979) Gopinathan Nair, VRice seeds were treated with two doses each of gamma rays and EMS. The tillers on Mj plants were classified according to their node positions. The frequencies of emergence for the various tiller categories were estimated. The M2 generation was raised as M! ear progenies. Chlorophyll mutation frequency and segregation ratio were estimated in the different ear categories. The frequencies of emergence for the various categories of tillers were different. The main shoot developed with the highest frequency followed by the primaries and the secondaries. Tillers in the axils of the coleoptile and the first primary leaf did not normally develop. The frequency of emergence of primary tillers increased upto the fourth and thereafter giadual'y decreased. Early primaries developed more secondaries than later ones. Mutation frequency of the main ear did not differ appreciably from that of primary ears Secondary groups (4) and (5) mutated more frequently than the respective primaries. The segregation ratios for the main ear and primaries were mostly similar. The ratios for the secondaries were higher. This high segregation ratio indicates that secondary ears are derived from smaller number of initial cells.Item Embryonic differentiation in rice seeds as revealed in mutational analysis(Kerala Agricultural University, 1976) Gopinathan Nair, VItem Effect of combined mutagenic treatments on sensitivity and mutation frequency in rice(Kerala Agricultural University, 1977) Gopinathan Nair, VPuce seeds were subjected to two sets of combination treatments of radiations and NMH. The effects of mutagenic treatments in the MI and M2 generations were recorded and discussed. Mutation frequencies estimated as number of mutations per 100 M, ears were not higher than the values expected on the basis of additive effects. When estimated as number of mutants per ]00 M plants, the frequencies revealed more than additive effects. The synergistic effect on mutant frequencies was due to increase in the segregation ratio of mutants. This effect was more pronounced at the higher dose combinations of fast neutrons and NMH.Item Effect of recurrent and alternate mutagenic treatments in rice(Kerala Agricultural University, 1978) Gopinathan Nair, VThe effects of repeated mutagenic treatment in the M2- and M3- gene. ation* in rice are reported. Recurrent irradiation with gamma rays and alternate treatment with gamma rays and NMH, neither increased the sensitivity of seeds r enhanced the frequency of induced chlorophyll mutations. This indicate that e inspite of its secondary polyploid nature behaves like a diploid in its reppo to the action of mutagens.