Effects of gamma irradiation on submergence tolerance of two selected varieties of lowland rice (Oryza sativa L.)

The study was carried out to assess the effect of different doses of gamma irradiation on agro-morphological traits under simulated flooding of two rice varieties (FARO 44 and FARO 60) in order to identify the most effective radiation dose in creation of genetic variability for submergence tolerance. Seeds of FARO 44 and FARO 60 cultivars were collected from National Cereal Research Institute (NCRI) Badeggi, Nigeria and exposed to different doses of gamma irradiation (0, 50,100, 150 and 200 Gy) at Center for Energy and Research Training, Zaria, Nigeria. The treated and the controls seeds were evaluated for submergence in a Randomized Complete Block Design with four replicate each. Each experimental bucket was flooded for a period of 10 days and was allowed to grow till harvest after submergence period. From the results, gamma irradiation had significant (P≤0.05) positive effect on survival percentage of FARO 44 after submergence with 150 Gy having the highest (93.75%) compared to the control (56.25%). The irradiation doses (150 and 200 Gy) had significant positive effects (p≤0.05) on the plant height and yield of FARO 44. In Faro 60, low doses of gamma irradiation (100 Gy) had significant (p≤0.05) effects on the days to 50% flowering and weight of 100 grains (g). It was observed that gamma radiation doses of 150 Gy and 200 Gy had positive effects on submergence tolerance indices of FARO 44 used in this research. Further research therefore should be carried out on submergence tolerance of the promising mutants.