Differential Morpho-Agronomic and Physiological Responses of Grass Pea (Lathyrus sativus L.) and Lentil (Lens culinaris Medik.) Genotypes to Arsenic

Abstract

Tolerance of four improved grass pea and lentil genotypes to arsenic (As) was tested in pot experiment using 30 mg As l -1 up to 60 days of growth after commencement of treatment (DAC). As exposure significantly reduced growth and seed yield of lentil variety VLM1 and VLM 4, but no such effect was observed in grass pea variety BioL-202 and PUSA-90-2. Results revealed normal leaf photosynthesis and antioxidant metabolism in both lentil varieties at 20 DAC. However, high superoxide dismutase activity coupled with low ascorbate and glutathione redox and declining ascorbate peroxidase as well as glutathione reductase (GR) level led to abnormal rise in H2O2 content at reproductive stages (40 and 60 DAC), consequently, resulting in significantly enhanced As-induced oxidative damage and physiological impediment in both varieties. By contrast, H2O2 level in both the grass pea varieties were modulated in fine tune at reproductive stage by balanced action of H2O2-metabolizing defense, powered by effective regeneration of glutathione through normal to high GR activity. This favored plant growth and ensured good grain yield in grass pea varieties even after prolonged As-exposure by effectively preventing oxidative damage. Results revealed criticality of foliar H2O2 level in determining As-tolerance of lentil and grass pea genotypes.