Salinity Effect at Seedling and Flowering Stages of Some Rice Lines and Varieties (Oryza sativa L.)

This study used 10 rice lines and varieties, including the salt tolerant variety (Pokkali) and salt susceptible variety (IR29) as control. Experiment for screening rice salinity tolerance at seedling stage was conducted in hydroponic system using five different salinity concentrations (0, 4, 6, 8 and 10 dS/m). Flowering stage was evaluated at the salinity level of 8 dS/m. The experiment was designed in randomized completely block (RCBD) with three replications for each line/variety under non-saline and saline condition. The results showed that the growth of rice lines/varieties was retarded severely with increasing salinity levels, and almost all of leaves were drying and dead completely (score 7 and 9). Plants of IR29 and OM7347 were dead at the electrical conductivity (EC) = 10 dS/m, whereas Pokkali (the tolerant variety) and IR93350 were evaluated at score 5. Salinity stress caused the reduction of overall vigor of rice lines/varieties especially in the pollen germination, fertilization and grain yield. Rice lines/varieties were classified to salinity tolerance levels as following: IR5040, IR93350, IR86385-8D-1-2-B and Pokkali (tolerant); OM8104, IR93340 and IR93343 (moderate susceptible); OM7347, IR87832-303-1-B and IR29 (susceptible).