Effect of Natural Ageing on Physiological and Biochemical Behaviour of Onion Seeds having Differential Initial Seed Quality

Abstract

Onion seeds are short-lived and the seed quality deteriorates during storage. The understanding of seed deterioration associated with the ROS content along with the antioxidant enzyme activities specifically in relation with initial seed germination potential is not available. A study was carried out in ICAR- Indian Agricultural Research Institute, New Delhi, India to assess the biochemical changes in onion genotypes under natural storage conditions during the year 2022-23. Freshly harvested seeds of four onion genotypes i.e. Sukhsagar, POS 24K, Bhima Super and Bhima Shubhra, having different initial seed germination percentage ranging from 84 to 96 % were stored under ambient conditions for 12 months. The seed germination declined to 49 to 77 % after 12 months with a percent decline in germination ranging from 19% to 46%. An increase in the activity of NADPH oxidase, ROS as well as malondialdehyde content and decline in antioxidant enzyme activity was observed in onion seeds after storage. A significant positive correlation was found among germination percentage, catalase, peroxidase and superoxide dismutase activity, whereas germination percentage was negatively correlated with superoxide radical, hydrogen peroxide, MDA content and NADPH oxidase activity. The study implicated the critical role of antioxidant enzymes in ameliorating the negative impact of ROS that causes seed deterioration with ageing without being affected by initial seed quality.