Study on the Irradiated Rice Manaw Thukha (Mashuri-M) for the Salinity Tolerance at Vegetative and Reproductive Stages
Nowadays, the whole world is facing climate changes such as flood, salinity and drought. Crops cultivated in central Myanmar are also badly affected by such climate changes. This fact necessitates to develop crop varieties that can tolerate environmental changes. In this study, Manawthukha var. irradiated by Gamma irradiation, which can tolerate salinity, is chosen. Screening under field conditions is difficult due to stress heterogeneity, presence of other soil-related stresses, and the significant influence of environmental factors such as temperature, relative humidity, and solar radiation. Saline soils are usually under waterlogged condition; other crops could not grow in these areas except rice. Dry seeds of Manawthukha were exposed to gamma radiation ranging from 0Gy to 400Gy to determine their responses to radiation and the effective doses for mutation breeding. The M1 seeds of this variety were sown in the field along with the control (non-irradiated seeds) and then, they were harvested. The main panicles from M1 were sown in the laboratory screening for M2 generation. In M3 generation, it was observed that plant height, panicle length and 1000 grains weight of some selected mutant lines were higher than that of the control plants. Reducing yield per hill affected by the late flowering can be seen in MK-C mutant lines. The experiment of hydroponic screening with the dose of 400 Gy was tolerant than other gray at seedling stage in M2 generation. However, filled grains per panicle and yield per hill of M1 were generally decreased with the increasing doses of gamma ray. In M4 generation, it was observed that MK-A, MK-A1, MK-B1, MK-C1, MK-D2, MK-F, MK-F2, and MK-F4 mutant lines and control seeds became sterile under saline condition though the heading was appeared.
Keywords - Manawthukha, Gamma Irradiation, Mutation, Salinity Tolerance, Vegetative stage, Reproductive srtage.