Contribution to the improvement of rice (Oryza sativa L.) by mutation induction with gamma radiation

The study involved inducing mutations in the varieties Icta-Virginia and Precozicta to obtain genotypes that mature early, are resistant or tolerant to Pyricularia oryzae and have a high yield potential. To optimize the radiation dose for each variety, seeds were irradiated with doses of 0, 150, 200, 250, 300 and 400 Gy. Six thousand seeds of each variety were irradiated with the above doses to establish the M1 generation, in which the physiological effects and somatic mutations were observed. The M2 generation was sown in progeny groups and as the crop developed, mutants with chlorophyll changes, morphological changes, improved yield, tolerance to Phyricularia oryzae and mutants which matured earlier than the original variety were identified and selected. In the M3 generation, derived from the Icta-Virginia and Precozicta varieties, the genetic stability of mutants with morphological changes, chlorophyll changes, tolerance to Pyricularia oryzae (classified as 0-1 on the 0 to 9 scale of the standard rice evaluation system) and those which matured earlier (15 to 20 days) than the original variety was confirmed. (author). 7 refs, 3 tabs