High temperature-induced oxidative stress in Lens culinaris, role of antioxidants and amelioration of stress by chemical pre-treatments

Abstract

Six varieties of lentil (Lens culinaris Medik.) – Asha, Subrata, IPL 406, IPL 81, Lv and Sehore – were exposed to temperatures ranging from 30–50°C which resulted in retarded germination and seedling growth at higher temperatures. Tolerance index and membrane stability tests revealed Sehore and Lv to be susceptible to elevated temperatures while IPL 406, IPL 81, Asha and Subrata were tolerant. Catalase, ascorbate peroxidase and superoxide dismutase showed an initial increase before declining at 50°C, while peroxidase and glutathione reductase activities declined at all temperatures. Lipid peroxidation significantly increased in all varieties. In the tolerant varieties, there was an initial decrease in accumulation of H2O2 followed by an increase from 40°C onwards; however, in the susceptible varieties, accumulation was enhanced at all high temperatures. Ascorbate and glutathione also showed initial increase followed by a decline. Total antioxidant activity was at a maximum at 35–40°C in the tolerant varieties and at 30°C in the susceptible ones. Oxidative stress induced by high temperature was ameliorated by treatment with salicylic acid, abscisic acid or CaCl2, of which salicylic acid was the most effective.