An efficient callus induction and plant regeneration system has been developed using salt and heat as pre-treatment factors for three barley genotypes viz. BB-3, BB-6 and BHL-18. Different concentrations of NaCl (1.5, 2.5, 3.5, 4.5, 5.5 and 6.5 g/L) were used and its effects were determined on the basis of the viability of callus (CV), plant regeneration (PR), relative growth rate (RGR) and tolerance index (TI). The BB-6 showed highest performance on tolerance based on CV (14.72%), PR (7.69%), RGR (0.91%) and TI (0.42%) at 6.5 g/L NaCl. Various NaCl concentrations displayed significantly differences at P < 0.01 level as compared with the control. Plant regeneration capability was recorded after heat pre-treatment using calli at 30, 35 and 40 °C. In this study, BHL-18 produced highest callus induction (59.71%) after desiccated at 40 °C for BB-6. Highest regeneration was recorded around 41.66% when 4 weeks old calli were pre-treated at 35 °C. Furthermore, heat pre-treatment factors were very effective for enhancing plant regeneration (25-41.66%) which was 1.8-2.14 fold higher compared to the control (13.88-19.44%). Hence, heat treated calli displayed higher tolerance level to survive in NaCl-induced treatment for determining abiotic stress and increased regeneration rate at 35 °C temperature in BB-6 barley genotype.
Keywords: Barley; NaCl; Regeneration; Relative growth rate; Tolerance index.