Effect of saline treatment on seed germination of adzuki beans

Salinity is one of the major causes of abiotic stress for plant development and growth worldwide, and affects crop yield significantly. To analyse the level of salinity tolerance among ‘Ji Hong 20’ (JH20), ‘Jin Xiao Dou 5’ (JXD5) and ‘Jin Xiao Dou 6’ (JXD6) adzuki bean cultivars, nine saline levels (0.0, 32.5, 65.0, 97.5, 130.0, 162.5, 195.0, 227.5 and 260.0 mmol L-1 NaCl) were applied during seed germination. Germination potentials and final germination percentages of all cultivars were significantly reduced by NaCl with the level at which germination was affected being dependent on cultivar. The JXD5 seeds had the highest germination index and vigour index at the same NaCl concentrations, followed by the JH20 and then JXD6 seeds. The shoot and root lengths of JH20 and JXD5 were significantly shorter at NaCl concentrations > 65.0 mmol L-1, while those of JXD6 were reduced at salinity > 32.5 mmol L-1. Quadratic regression models could well predict the germination percentage of JH20, JXD5 and JXD6 seeds under saline stress.