Alleviation of adverse effects of salt stress on lettuce (Lactuca sativa var. crispa) by application of vermicompost

In arid and semiarid regions, soil salinity causes the salt stress in plants and negatively affects the crop production. In this respect, organic farming practices are becoming the foreground as applications that are sensitive to the environment and support sustainability in agriculture. This study aimed to explain the role of vermicompost (VC) for reducing the effect of salt stress on lettuce (Lactuca sativa var. crispa) plant. The experiments were performed with different concentrations of VC (0, 2.5 and 5% VC on a weight per weight basis of soil-w/w) and salt stress treatments (4 and 8 dS m–1 NaCl levels). Under salt stress, shoot height, relative water content (RWC), stomatal conductance (gs), chlorophyll a (Chla) content decreased, while electrolyte leakage (EL), malondialdehyde (MDA) contents and superoxide dismutase (SOD) and catalase (CAT) activities significantly increased in parallel with the severity of the stress. In this study, VC under the salinity stress significantly increased the RWC, gs and Chla, Chlt and carotenoid contents in the leaf tissues; however, MDA and EL contents decreased and SOD and CAT activities increased compared to the controls. In all levels of NaCl, the 5% ratio of VC significantly reduced the negative effects of salinity.