Seed development and acquisition of desiccation tolerance during maturation of okra seed

摘要

Studies on seed development and maturation were conducted during kharif 2008. Okra seeds of Pusa A-4 cultivar were harvested 10, 17, 24, 28, 32, 36 and 40 days after anthesis (DAA). Seeds were immediately shelled by hand and a part of freshly harvested seeds were analyzed for moisture content, leachate conductivity, seed dry weight and seed germination. Other part of the freshly harvested seeds at each sampling date was subjected to rapid desiccation to identify the stage at which desiccation tolerance occurred. With the advancement of seed development, seed coat colour changed from white to grey. Maximum hard seeds were found when seed coat colour changed to grey at 40 days after anthesis. No seeds germinated until 17 DAA. As soon as seeds began togerminate at 28 DAA, the percentage of hard seeds increased as seed moisture content decreased. There were no hard seed in fresh seeds and rapidly dried seeds with the higher moisture content till 24 DAA. With the advancement of seed development there was a drastic reduction in moisture content and the occurrence of hard seeds were observed. Maximum hard seeds were found when seed moisture content was minimum at 40 days after anthesis in fresh developing and rapidly dried seeds. Maximum seed germination in fresh developing seeds was attained at 36 DAA, when physiological maturity and maximum seed dry weight were attained. With seed maturation, there were rapid decline in leachate conductivity and seed moisture content. Total soluble sugars increased from 10 to 36 DAA and non-reducing sugars increased drastically at 28 DAA, which was concomitant to the stage at which desiccation tolerance occurred.