Tiller emergence in rice and mutation frequency in the different ear categories

Abstract

Rice 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.