Study of the effect of salicylic acid foliar application and application of biofertilizers on yield, physiological characteristics and antioxidant defense system of bean under drought stress

This study was performed to investigate the effect of foliar application of salicylic acid and application of biofertilizers on yield and physiological characteristics of white beans under drought stress. The experiment was conducted during two years of 2018 and 2019 in Boroujerd Agricultural and Natural Resources Research Campus located in Lorestan province as a split factorial split in a randomized complete block design with four replications. In the main plots, drought stress treatment was at the two levels of presence and absence of drought stress in the form of defecit-irrigation. Also, in the subplots, two factors of biofertilizer and salicylic acid were factorial. Phosphorus biofertilizer treatment included three levels of control and application of Bacillus and Pseudomonas bacteria. Salicylic acid treatment also included foliar application of salicylic acid at levels of 0, 1 and 2 mM. The results of combined analysis showed the effect of year treatment, drought stress, salicylic acid, biofertilizers and also their interaction on physiological characteristics such as chlorophyll a, b, total, relative leaf water content, soluble protein and catalase and superoxide dismutase enzymes. Drought stress increased the proline content and decreased soluble protein content and relative leaf water content, while the use of salicylic acid and biofertilizers under drought stress conditions improved these traits. The activity of superoxide dismutase was significantly increased by the use of salicylic acid and biofertilizers. Drought stress decreased grain yield and although in both stress and lack of stress application of biofertilizers increased grain yield, but the highest grain yield of 2937 kg / ha was obtained in Pseudomonas application treatment. Overall, the results of this study showed that under drought stress conditions that the physiological characteristics of the plant are not in favorable conditions caused a 55% reduction in grain yield. Application of salicylic acid improved the physiological properties and increased the antioxidant activity of the plant, which eventually increased the grain yield by improving these properties. The application of Bacillus and Pseudomonas biofertilizers also improved the physiological characteristics of the plant and subsequently increased the grain yield of white beans and increased the grain yield by 14% and 24%, respectively.