부산대학교 도서관

Mutation breeding offers a simple and effective means of inducing genetic variation followed by trait selection to improve the traditional rice landraces. Gamma ray induced mutagenesis is most commonly used to obtain chlorophyll mutants and economically useful mutants in many crops. In the present study, gamma ray induced (300Gy) mutagenesis was carried out in the three rice landraces viz., Samundchini, Vishnubhog and Jhilli to study the frequency and spectrum of macro and micro mutations. Macro mutations including four categories of chlorophyll mutations along with many viable mutations viz. mutants with reduced height, reduced maturity duration, high tillers, clustered grain type, dark green leaves, strong stem and grassy types were identified in the M2 population. A total of 81, 98 and 51 putative macro mutants were observed in Samundchini, Vishnubhog and Jhilli with mutation frequency (%) 0.591, 0.796 and 0.434, respectively. Furthermore, 45, 56 and 32 chlorophyll mutants with the 0.382, 0.455 and 0.272 mutation frequency percentages were observed in the M2 population of Samundchini, Vishnubhog and Jhilli, respectively. In addition, 36, 42 and 19 viable morphological mutants with the mutation frequency percentages (based on M2 population) 0.263, 0.341 and 0.162 were identified in Samundchini, Vishnubhog and Jhilli, respectively. Also, variations in mean, widening of the range and increase in the coefficient of variation for most of the quantitative traits in mutagen treated populations as compared to control depicts the existence of micro-mutation and release of polygenic variability in all the three mutagenic populations. Many economically important mutants were identified in all three landraces which could be further advanced for varietal development and use in the breeding program.