MORPHO-PHYSIOLOGICAL, YIELD AND OXIDATIVE STRESS RESPONSES OF SESAME UNDER WATERLOGGING STRESS

Abstract

Waterlogging is one of the most devastating abiotic stresses which often results in oxidative stress to plants. Sesame (Sesamum indicum L. cv. BARI Til-4) is extremely susceptible to anaerobic environment induced by waterlogging and the hypoxic/anoxic condition which results in the reduced growth and yield along with the overproduction of various reactive oxygen species (ROS; O 1 O 2 iii

2 • − , OH ). The present study was designed to investigate the duration-dependent changes in the morpho-physiological, anatomical and biochemical attributes of sesame to waterlogging stress. The sesame plants were subjected to waterlogging for 2, 4 and 6 days at vegetative, reproductive and maturity stage of plant growth and the data were measured after completion of the each treatment duration. A treatment with 8 days waterlogging duration was added for the biochemical study. Present study proves that waterlogging exerts severe damage effect on different physiological parameters and yield attributes of sesame plant. The plants showed an increasing trend in the lipid peroxidation, H 2 O and methylglyoxal (MG) content with the increasing duration of stress. Proline (Pro) content was slightly decreased along with the leaf relative water content (RWC) with increasing duration of waterlogging. Photosynthetic pigments like chlorophyll a, b, and total chlorophyll and carotenoid contents also decreased with time in stressed plants. The content of glutathione (GSH) and oxidized glutathione (GSSG) increased, while the ratio of GSH/GSSG and Ascorbate (AsA) content decreased which indicates the the disruption of redox balance in the cell. Activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR) and glutathione peroxidase (GPX) increased, while the dehydroascorbate 2 reductase (DHAR), glutathione reductase (GR) and catalase (CAT) activities mostly decreased. Waterlogging modulated the glyoxalase system mostly by enhancing glyoxalse II (Gly II) activities with a slight increase in glyoxalse I (Gly I). So, the present study also proves the induction of oxidative stress under waterlogging stress in sesame plants and the enhancement of the stress level with increasing duration.