Rice is susceptible to salt stress at seedling and reproductive stages. In order to identify the specific region in the genome conferring salt tolerance trait, F2 population of the Thai landrace salt tolerant variety, "eJao Khao"e and the salt susceptible line, IR29, was generated. Based on the phenotype of "eJao Khao"e under salt stress condition, it is clustered with "ePokkali"e, which is the salt tolerant standard cultivar. The phenotyping of 600 F2 individuals was performed in the hydroponic system. Two-week old seedlings were treated with stepwise salt stress using NaCl solution to reach 12 dS.m-1 for 12 days. The F2 members showed a high level of distribution in salt injury score determined according to the standard salt injury evaluation system (SES), cell membrane stability (CMS), relative water content (RWC), whole plant fresh weight, plant height and root length. SES distribution tended to show the random distribution, while CMS and RWC had bimodal distribution. The whole plant fresh weight after 12 days of salt stress displayed right skewed distribution. For the plant height and root length, both values displayed normal distribution. All of the parameters show correlation to one another. SES shows the strong negative correlation with CMS (-0.9), RWC (-0.9), and whole plant fresh weight (-0.8), but it shows less negative correlation with plant height (-0.6) and root length (-0.5). This F2 population can be used to identify the salt tolerance regions from "eJao Khao"e via bulk-segregant analysis in the future.
Keywords
cell membrane stability; relative water content; rice; salt tolerance