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.
