Development of a varietial screening procedure for salt tolerance of rice (Oryza sativa L.) varieties at germination stage

Germination rates were studied using four salt tolerant varieties (At 95-26-4, At 401, Pokkali, Bw 400), one with unknown reaction to salinity (Bg352) and two salt susceptible varieties (Bg 94-1, Bg 350). In the experiment hundred seeds from each of the above varieties were placed in each Petri dish of different salt concentrations (pre test; 0 ds/m, 10 ds/m, 20 ds/m, 30 ds/m and in the experiment; 0 ds/m, 18 ds/m, 21 ds/m, 24 ds/m, 27 ds/m). The pre test was conducted to find out the effective range of salt concentration for the test. There were no significant differences in germination rate among the varieties until 20ds/m salt concentration. Germination rates of all the varieties at 30ds/m salt level were significantly suppressed compared to lower salt level. Salinity tolerant varieties maintained high germination rate up to the level of salt at 21ds/m, whereas salinity susceptible varieties maintained only up to 20ds/m. The results of this study indicated that the rate of seed germination of salinity susceptible varieties were significantly different from salinity tolerant varieties at 21 ds/m salt level. Results emphasized that the salt concentration of 21ds/m can be used as a tool to distinguish between susceptible and resistance rice varieties at the seedling stage by comparing germination rate.