Effects of Vermicompost on Some Morphological, Physiological and Biochemical Parameters of Lettuce (Lactuca sativa var. crispa) under Drought Stress

Abstract

Vermicompost can play an effective and important role in plant growth and development and also in reducing harmful effects of various environmental stresses on plants. The vermicompost fertilizer application was evaluated for the growth, physiological and biochemical parameters of lettuce (Lactuca sativa var. crispa) plants under drought stress conditions. Tests were carried out at different levels of vermicompost (0, 2.5 and 5%) and drought stress [no stress, moderate drought, and severe drought at 100, 50 and 25% of field capacity]. In comparison to control (vermicompost at 0%), lettuce plants treated with vermicompost at 2.5 or 5% had higher shoot height, shoot fresh weight, relative water content, stomatal conductance, chlorophyll a, chlorophyll b , total chlorophyll and carotenoid contents under moderate and severe drought stress conditions. Malondialdehyde (MDA) content and superoxide dismutase (SOD) and catalase (CAT) activities increased while plants under drought stress conditions. Application of vermicompost caused higher SOD and CAT enzyme activities and lower MDA content under drought stress. Enhancement in antioxidant enzyme activities as a result of vermicompost destroyed reactive oxygen species. Therefore, application of vermicompost under moderate and severe drought stress decreased MDA content in lettuce plant cells. Data indicated a positive effect of the vermicompost on the growth of lettuce under drought stress conditions.