DUS characterization and genetic variability studies of rice mutants

Forty five mutant lines developed using gamma rays and electron beam irradiation in the background of ADT 37 and ADT R) 45 were characterized for twenty four DUS characters. Out of the twelve visually assessed qualitative traits, shape of ligule, colour of ligule, stigma colour, sterile lemma colour, panicle secondary branching and panicle attitude were monomorphic, culm attitude, panicle exertion, flag leaf attitude, presence of awns and distribution of awns were dimorphic and the grain shape was polymorphic. The analysis of variance revealed the existence of significant differences among genotypes for six characters viz., days to 50% flowering, plant height, number of productive tillers, number of filled grains per panicle, single plant yield and panicle length. The traits viz., number of productive tillers, number of filled grains per panicle, 1000 grain weight, leaf blade width, LB ratio and single plant yield had high heritability along with genetic advance as percent of mean. These characters are governed by additive gene action and improvement in these characters would be possible through direct selection. The diversity analysis of both qualitative and quantitative characters grouped the mutant lines into seven clusters. Among the seven clusters, the maximum number of genotypes (27) present in cluster IV. The intra cluster distance was maximum in cluster I and the highest inter-cluster distance was recorded between cluster I and cluster VI. Five mutant lines viz., M6, M66, M79, M85 and M88 of ADT (R) 45 were identified as desirable lines based on nonlodging habit and increase in 1000 grain weight and six mutant lines viz., M69, M71, M78, M79, M85 and M88 of ADT 37 with medium slender grain type were selected as novel mutants. These selected lines will be promoted to yield trials. Two unique mutant lines M 37 and M 39 of ADT (R) 45 with distinct culm and flag leaf attitude were selected as desirable mutants and these will be registered under PPV&FR Act for obtaining plant breeder's rights.