Effect of foliar application of 24-epibrassinolide and salicylic acid on common bean plants grown under drought stress

The aim of this study was to evaluate the potential use of two bioregulators, 24-epibrassinolide (BR) and salicylic acid (SA), as attenuators of drought stress on common bean plants (Phaseolus vulgaris L.). This was done by subjecting the plants to three different soil moisture levels, and then analyzing: gas exchange by the leaves, enzymes of antioxidant metabolism (superoxide dismutase, catalase and ascorbate peroxidase), total soluble protein content, photosynthetic pigments, relative leaf water content, and biometric parameters. Neither SA nor BR had significant effects on the parameters of gas exchange and photosynthetic pigments, but they helped to regulate the levels of hydrogen peroxide in the plants, by adjusting both ascorbate peroxidase activity and catalase activity. Therefore, SA and BR are considered to be useful treatments for increasing tolerance to water stress in common bean plants, because their use caused improvements in the plants' protective mechanisms against drought stress, without any detrimental side effects.