The potential role of seed priming with ascorbic acid and nicotinamide and their interactions to enhance salt tolerance in broad bean (Vicia faba L.)

Seed priming with vitamins is an efficient method for increasing seedlings growth and productivity under stressful conditions. This study aimed to investigate the priming of broad bean (Vicia faba L.) seeds using 100 mg L ascorbic acid and nicotinamide and to study their interactions on growth and some physiological parameters of plant under salt stress (150 mM NaCl) for 4 weeks. Salinity treatment significantly reduced growth parameters, water status, photosynthetic pigments, soluble proteins, K, and Mg ions contents. On the other hand, soluble carbohydrates, free amino acids, proline, ion leakage, Na and Cl ions were significantly increased compared to control. However, application of the two vitamins individually or in interaction increased the photosynthetic pigments, soluble carbohydrates and proteins, proline and free amino acids content, while transpiration and ion leakage were decreased. In addition, K/Na ratio was increased, whereas Na, Cl and Na/K ratio were decreased. The SDS-PAGE analysis showed that salinity induced the synthesis of protein bands with molecular weights of 161, 101, 43 and 37 KDa and disappearance of 40, 28 and 17 KDa, compared to control. Application of vitamins induced the synthesis of additional protein bands with molecular weights of 28 and 17 KDa such as those appeared after treatment with vitamins C; and 56, 40 and 28 KDa under vitamin PP treatment. Moreover, three protein bands which disappeared under salinity stress were reappeared in response to vitamin treatments. The stimulatory effects of vitamin PP on the growth and other related metabolic activities were greater than that of vitamin C. However, these stimulatory effects were higher when they were applied in combination. The above results pave the way to gain the insight into the potential role of these vitamins to improve the salt tolerance of broad bean plant