Morphological and molecular screening of rice accessions for salt tolerance

The ever-increasing demand for rice raises the need to increase productivity by using salt tolerant varieties on saline soils. In this study, 12 rice accessions were screened for tolerance to salt at seedling stage using morphological and molecular methods. The study was carried out in a hydroponic system using Hoagland solution. Scoring was done using the modified standard evaluation score (SES) system after 14 days of treatment. Salt tolerance indices were estimated from shoot length, root length and total biomass. For molecular studies, ten Simple Sequence Repeats (SSR) primers linked with salt tolerance Quantitative Trait Loci (QTL) were used. Results showed greater reductions in biomass and shoot growth of susceptible accessions compared to the tolerant ones. The effect of salt stress on root length showed variability among accessions as well as concentrations. UPIA 1, UPIA 2, FARO 52, FARO 61, TOG 5681 and FARO 44 had similar banding patterns with POKALLI (check variety) suggesting that they may contain salt tolerance genes. Of these accessions, only POKALLI and UPIA 2 survived all levels of salt concentration tested and thus got the highest SES score of one. Both accessions also had the highest overall mean salt tolerance indices. In conclusion, based on SES scores, salt tolerance indices and SSR data, POKALLI and UPIA 2 were identified as highly tolerant, FARO61, FARO 52, UPIA 1 and TOG 5980A as tolerant while WITA 12, CG12, TOG1670, TOG 5681 and TOG 5485 were highly susceptible. Such information will be useful in the selection of parents as breeding lines for salt tolerance.   Key words: Rice, seedling stage, hydroponics, salt tolerance index, simple sequence repeats (SSR) primers.