Effects of desiccation on the lipid peroxidation and activities of peroxidase and polyphenoloxidase in seeds of Telfairia occidentalis

Abstract

Seeds of Telfairia occidentalis Hoof (fam. Cucurbitaceae) were examined for their desiccation tolerance at different temperatures (5°C, 30°C) and drying rates. Seeds were intolerant of desiccation and required fairly high moisture contents (about 40% or more) to remain viable. Limited desiccation stimulated germination of the seeds, adding support to the local practice of sun drying seeds before sowing. Activities of peroxidase and polyphenoloxidase were suppressed when seeds were dried to moisture contents less than 40%, identified as the eritical moisture content for survival. Significant negative correlations were found between hydroperoxide levels and germination (r = -0.98) and between hydroperoxide levels and moisture content (r = -0.82) in seeds dried over CaCl 2 at 5°C. Results suggest that an increase in hydroperoxide levels may be associatec with declining seed viability and that peroxidation may occur with desiccation in seeds of Telfairia occiden talis. Peroxidation was affected by the temperature and rate of desiccation.