Salicylic and jasmonic acid attenuate the salt stress effects in lettuce

Abstract

Abstract Salt stress reduces growth and change physiological and biochemical responses of plants. Salicylic acid (SA) and jasmonic acid (JA) are plant hormones involved in plant defense metabolism against abiotic stress. Therefore, the objective was to evaluate whether the foliar application of SA and JA, isolated or combined, attenuate the salt stress effects, as well as its possible effects on the physiological, biochemical and growth responses of lettuce plants. The plants were arranged in a completely randomized design, factorial scheme, with three salinity levels (1.65; 3.65 and 7.65 dS m− 1) and foliar application of SA (0 and 500 µM) and JA (0 and 100 µM). Photosynthesis, transpiration, stomatal conductance, internal carbon concentration, chlorophyll content, malondialdehyde (MDA) content, proline, relative membrane conductivity, soluble proteins, total and reducing sugars and phenols of lettuce leaves and roots were determined. Under the highest salinity level, shoot and root fresh weight reduced by 21.84% and 13.80%. Gas exchange also reduced by salinity, except for net photosynthesis. The combined application (SA + JA) increased the total soluble sugar content in leaves by 74.23%. Under moderate salinity, application of these growth regulators isolated induced the highest total sugar content in leaves. Proline content in leaves was higher under the highest salinity level and without application of growth regulators. However, with SA application, leaf proline content was reduced by 37.92%, while root proline increased with SA application under the highest salinity level. Exogenous application of salicylic acid and jasmonic acid improve salt stress tolerance in lettuce plants, although jasmonic acid is more effective than salicylic acid.