GENETIC AND MOLECULAR EVALUATION OF RICE (Oryza sativa L.) GENOTYPES FOR SALINITY TOLERANCE AT SEEDLING STAGE

This study aimed to screen 25 rice genotypes (Oryza saliva L.) for better tolerance against salinity stress at seedling stage and to identify the markers that could be effectively used for discriminating the salt tolerant rice genotypes. Two treatments were used i.e. control (without NaCl) and salinity (12 dSm(-1)). Ten traits were studied i.e. root length, shoot length, root/shoot length ratio, root fresh weight, shoot fresh weight, root dry weight, shoot dry weight, root/shoot dry weight ratio, SPAD value and K+/Na+ ratio. Molecular analysis was carried out to study the Saltol region in the studied genotypes using two SSR markers (RM493 and RM10711) and two STS markers (Wn11466 and Wn13903). The results indicated that FL478, RBL-236, RBL-238 and RBL-252 exhibited the best performance under salt stress regarding the studied traits. Based on principal component analysis, the traits root fresh weight, shoot fresh weight, root dry weight, shoot dry weight, root/shoot length ratio root/shoot dry weight ratio and K+/Na+ ratio were promising indicators of salt tolerance in rice. Concerning molecular analysis, five haplotypes were recognized using FL478 as a reference. Based on haplotype analysis, the 15 RBL lines exhibited similarity with FL478 haplotype and all of them have been determined to be tolerant to salt stress. Thus, some of these salt tolerant genotypes might be potential donors for the introgression salinity tolerant genes/QTLs for salt tolerance in rice breeding programms. Both markers RM493 and. RM10711 were able to differentiate between the salt susceptible and tolerant rice genotypes. Hence, these markers could be effective for marker-assisted selection (MAS) for Saltol QTL in rice.