Advanced Mutant Line Developed from Fatemadhan Shows Salinity Tolerance at both Seedling and Reproductive Stages

The generation of high-yielding rice mutants and their assessment under salt stress offers a great possibility to isolate salt tolerant line(s) with desired trait of interest. Two separate experiments were conducted at the seedling and reproductive stages of rice to assess the level of salinity tolerance of few advanced high-yielding rice mutants. In the first experiment, rice seedlings were grown under hydroponic conditions and 14-day-old seedlings were subjected to salt stress (EC=10 dS/m; 7 days). Salt stress caused significant reduction in root and shoot length and biomass and leaf chlorophyll content; however, a little reduction was found in the mutant Line-1. In contrast, a sharp increase in shoot Na+/K+ ratio was found in all the genotypes except, Binadhan-10, FL-478 and the mutant Line-1, which exhibited little increased ratio. The second experiment involved exposure of plant to salt stress (EC=10 dS/m) for three weeks at the late booting stage in a sizable plastic tub filled with field soil. Salt stress resulted in a significant decrease in yield and yield attributing traits in all the genotypes except Binadhan-10. Grain yield per panicle was found significantly positive correlation with panicle length, the number of filled grains per panicle, and 100-seed weight under both control and salt stress conditions. Based on the studied traits and stress tolerance indices, Binadhan-10 and mutant Line-1 categorized as salt tolerant and rest of the genotypes were categorized as susceptible, which is also evident from the biplot of principal component analysis. Considering the results from both of the experiments, mutant Line-1 was found tolerant genotype at both seedling and reproductive stage. However, further studies are required to determine the genetic issues controlling the salinity tolerance in mutant Line-1 and the high-yield potential of mutant Line-65 under control condition in a way to develop salt tolerant and high-yielding rice varieties, respectively.