Selection of salt tolerant somaclones from indica rice through continuous in vitro and ex vitro sodium chloride stress

This study aimed at the selection of salt tolerant somaclones from four Bangladeshi indica rice genotypes through in vitro and ex vitro NaCl stress applied through step wise and non-step wise methods. Callogenesis was initiated under four different levels of non-step wise NaCl stress (50, 100, 150 and 200 mM) and subsequent plant regeneration was observed under same levels of NaCl stress. Among the four genotypes Binnatoa and IR51491-AC5–4 produced fertile somatic embryos with relatively high NaCl (150 mM) stress. BRRI dhan29 and BRRI dhan40 produced fertile somatic embryos only from 50 and 100 mM NaCl stress conditions. Ex vitro (glass house) step-wise NaCl stress was applied to in vitro selected somaclones at the seedling (50, 100, 150 and 200 mM) and following booting stages with simultaneous acclimatization. Satisfactory seedling survival was observed for all genotypes up to 150 mM NaCl stress. Advanced flowering was observed mostly for all the genotypes when stress was applied at the seedling stage compared with combined stress at both seedling and booting stages. Fertile SC1 generations were observed for genotype IR51491-AC5–4 and Binnatoa up to 200 mM NaCl stress applied at the seedling and both seedling and booting stages. Information on transmission of somaclonal variation to sexual progeny is required for further exploitation of potentially useful variants.