Physiological responses of peanut (Arachis hypogaea L.) cultivars to water deficit stress: status of oxidative stress and antioxidant enzyme activities

Abstract

From a field experiment, the changes in oxidative stress and antioxidant enzyme activities was studied in six Spanish peanut cultivars subjected to water deficit stress at two different stages viz. pegging and pod development stages. Imposition of water deficit stress significantly reduced relative water content, membrane stability and total carotenoid content in all the cultivars, whereas total chlorophyll content increased at initially and decreased at later stage. Chlorophyll a/b ratio increased under water deficit stress in most of the cultivars signifying greater damage to chlorophyll b rather than increase in chlorophyll a content. Oxidative stress measured in terms of H₂O₂ and superoxide radical content, and lipid peroxidation increased under water deficit stress, especially in susceptible cultivars viz. DRG 1, AK 159 and ICGV 86031. Relationship among different physiological parameters showed level of oxidative stress build-up was negatively correlated with activities of different antioxidant enzymes like superoxide dismutase, catalase, peroxidase, ascorbate peroxidase and glurathione reductase. The study concluded that in peanut water deficit stress at later stages of growth was more detrimental and an efficient antioxidant defense system manifested by higher activities of antioxidant enzymes was responsible for better stress tolerance in cultivars like ICGS 44 and TAG 24.