Induction of mutations affecting floral traits in rice (Oryza sativa L.)

Four improved indica varieties adapted to high altitude regions namely K 39-2, IET 11988, Himdhan and IET 11990 were treated with ethyl methane sulfonate, sodium azide and gamma rays with the objective of determining the most efficient mutagen and most responsive genotype for induction of mutations affecting predominantly reproductive parts and their functioning in rice. Frequency and spectrum of mutations affecting floral traits computed on M₁ plant progeny and M₂ population basis revealed the combination of the efficient sodium azide and the most responsive variety IET 11990 to be ideal for recovering highest number of selectively male sterile mutations. Among three kinds of male steriles viz., typical abortive, sporogenous and deformed male sex types recovered, critical study of abortive type helped identify several temperature sensitive genic male steriles, two of which are being improved for commercial exploitation in two-line hybrid breeding.