Alleviation of salt stress in fine aromatic rice by seed priming

Abstract

This study investigated the potential of seed priming for induction of salt tolerance in rice. The seeds of two fine aromatic rice cv. Shaheen Basmati (salt tolerant) and Basmati-2000 (salt sensitive) were soaked in aerated solutions of CaCl2 (Ψs=-1.25 MPa), KCl (Ψs=-1.25 MPa), and H2O2 (50 mM) each for 36 h. Seeds soaked in distilled water and non-primed seeds were taken as control for comparison. Two experiments were conducted in vitro and primed seeds were exposed to 0, 40 and 80 mM NaCl in petri dishes and sand culture during germination and emergence respectively. Priming with CaCl2 followed by KCl were more effective in inducing salt tolerance of both rice cultivars owing to enhanced germination capacity, speed of germination, seedling length and dry weight in saline medium. Incremental salinity reduced total chlorophyll percentage (TCP) by two fold in both cultivars but higher TCP was found at all salinity levels from CaCl2 primed raised seedlings in salt tolerant cultivar. Decreased leaf Na + accumulation and increased K+ uptake were found in CaCl2 primed seedlings at moderate salinity in both cultivars but effect was more pronounced in Shaheen Basmati. Delayed germination and seedling growth with H2O2 pre-treatment indicates sensitivity of H2O2 primed seeds to salts and might be the result of higher Na+ uptake and less chlorophyll contents in rice seedlings. Nonetheless, enhanced germination and seedling growth, high Na+/K+ exclusion indicates Shaheen Basmati tolerance to salinity than Basmati-2000 and seed priming with CaCl2 seems more promising in induction of salinity tolerance in fine aromatic rice.