Study of the Physiological and Biochemical Changes of Common bean in Response to Foliar Application of Salcylic Acid under Drought Stress Conditions

Drought stress is one of the most important factors limiting plant growth. Salicylic acid is a phenolic compound produced by plants that plays an important role in regulating various plant processes. Research has shown that external application of salicylic acid can increase plant tolerance to some abiotic stresses such as osmotic stress, drought, salinity, ozone and ultraviolet rays. The aim of this study was to investigate the interaction of drought stress and foliar application of salicylic acid on some physiological and biochemical parameters in bean genotypes.

To investigate the effect of salicylic acid on the physiological and biochemical trait of bean genotypes under drought stress, a factorial experiment based on randomized complete block design with three replicates was performed at 2020 in the research greenhouse of Agronomy and Plant Breeding, of the College of Agriculture and Natural Resources, University of Tehran in Karaj. The treatments included two genotyps of common bean (167drought tolerant and Naz drought sensitive), two levels of drought stress, 80% of field capacity (as control), and 40% of field capacity (severe drought stress) as well as two concentrations of salicylic acid 0, 1 mM. After applying the treatments, various physiological and biochemical traits were evaluated.

The results showed that drought stress significantly reduced ion leakage and significantly increased ion leakage, hydrogen peroxide and malondialdehyde in both genotypes. These changes under drought stress were far greater in Naz genotype than in genotype 167. Foliar application of salicylic acid reduced the amount of malondialdehyde, ion leakage and hydrogen peroxide and increased the activity of antioxidant enzymes, proline and relative content at all drought levels. The reduction of these changes in leaf foliar application by salicylic acid in Naz genotype was much greater than genotype 167.

The results showed that that foliar application of salicylic acid was able to maintain the leaf water status (relative leaf water content), maintain cell membrane stability (by reducing ion and malondialdehyde leakage), increase the amount of compatible solutions (proline) as well as increasing the Antioxidant enzymes activity (superoxide dismutase, catalase, ascorbate peroxidase and guaiacol peroxidase) in both bean genotypes and thus, reduce the negative effects of drought stress and make the plant more resistant. Therefore, the foliar application of 1 mM salicylic acid can be used to reduce the destructive effects of drought stress on bean genotypes.