Impact of exogenous application of salicylic acid on the drought-stress tolerance in pepper (Capsicum annuum L.)

To investigate the effect of drought stress on the physiological and chemical properties of the sweet pepper and the impact of the foliar application of salicylic acid (SA) on alleviating the negative effects of this stress, a factorial experiment was carried out using a completely randomized design in the greenhouse conditions. Drought stress levels were 100% field capacity (as control), moderate stress (60% field capacity), and severe stress (30% field capacity). Foliar SA was also applied at three concentrations of 0 (as control), 0.5, and 1 mM when the plants were at the four-leaf stage. The results showed that drought reduced shoot and root fresh weight and dry weight, relative leaf water content, fruit length and diameter, chlorophyll index, and leaf area, and increased electrical conductivity, antioxidant capacity, total phenolic content, ascorbate, polyphenol oxidase, and ascorbate peroxidase. After foliar of application SA, electrical conductivity decreased and other above-mentioned characteristics increased, however, the increase in shoot dry weight, root fresh weight, and chlorophyll index was not significant. From the results of this experiment, it can be concluded that SA alleviates the negative effects of drought stress in pepper.