The Effect of Salicylic Acid and Proline Foliar Application on Some Physiological Characteristics of Soybeen (Glycin Max L.) Under Irrigation by Saline Water

Salinity is one of the major challenges to increasing crop productivity. Besides these, in order to investigate of  proline and salicylic acid in the modulation of salt stress on soybean (Glycine max L.) , an experiment was conducted as split plot arrangement in a randomized completely design with four replication in 2016 in College of Agriculture, Shahrekord University. Main plot included three level irrigation by saline water with electrical conductivity 2 (control), 5 and 10 dS m-1 NaCl) and sub plot in four level of foliar applied (10 mM proline, in combination with 10 mM proline + 3 mM salicylic acid, 3 mM salicylic acid and sprayed with water (control)). The results showed that the 5 and 10 dS m-1 NaCl lead to increased and decreased of photosynthetic pigments compared with the control, respective. Proline and soluble sugars were increased under salt stress, while membrane stability index and relative water content decreased. Interaction between salt stress and foliar treatments showed that the highest increase in chl. b, carotenoid and proline were recorded in 5 dS m-1 NaCl and proline plus salicylic acid with increase of 93, 53 and 143% as compared to the control, respectively. Membrane stability index and relative water content were decreased 63 and 38% as compared to the control, respectively. So, foliar application of 10 mM proline with 3 mM salicylic acid on physiological parameters of soybean was the best treatment to mitigate the detrimental effects of salt stress. So, proline function as compatible solute in osmotic adjustment and salicylic acid with the protective role through physiological reactions under salt stress.