Developing Early-Flowering or Photoperiod-Insensitive Mutants from Rice var. Ayarmin (Machando) by Using Gamma Radiation from 60Co Source

Ayarmin is photoperiod-sensitive rice variety which can be grown once a year. It is cultivated in the Ayeyarwady, Sagaing and Mandalay regions in Myanmar and preferred by local customers. In this article, Ayarmin was used to develop photoperiod-insensitive or early-flowering mutants using gamma radiation. Dry seeds of rice, Ayarmin were irradiated with the dose of 200Gy, 250Gy, 300Gy and 350Gy of gamma rays from 60Co source. The main panicles in M1 generation were bulk-harvested and sown as M2 generation in summer for the selection of photoperiod-insensitive mutants. In M3 generation, potential mutant lines were sown in the field along with the control plants and early-flowering mutant lines were selected in the monsoon 2016. Eleven mutant lines were obtained in M3 generation, AYM-200B, AYM-200C, AYM-200D, AYM-200E, AYM-200F, AYM-200I and AYM-200J of 200Gy, AYM-250A of 250Gy, AYM-300C of 300Gy, and AYM-350A and AYM-350D of 350Gy. Some of these mutant lines had good quantitative and qualitative characters.