Biochemical changes during ageing in medicinal pumpkin: lipid peroxidation and membrane damage

Abstract

Seeds gradually lose their viability during storage. The damage that occurs at the biochemical level can alter the seed physiological status and is affected by the storage conditions of the seed. The lipid peroxidation through the production of free radical plays an important role in the loss of seed viability during seed storage. In the present study, we examined the relationship between the activity of free radical detoxifying enzymes, lipid peroxidation and seed deterioration in medicinal pumpkin (Cucurbita pepo subsp. Pepo. Convar. Pepo var. styriaca Greb) during storage. The seeds were incubated at different storage temperatures (35 and 5oC) and seed moisture content (5, 8 and 14%) for 2 and 4 days. Malondialdehyde content in seed was increased during storage with increasing moisture content and temperature, suggesting that seed deterioration was associated with lipid peroxidation. The increase in lipid peroxidation was related with increased electrical conductivity, which suggested membrane damage during deterioration. The decrease in germination was also associated with a decrease in catalase and peroxidase activity and as a result, the antioxidant system was not sufficient to protect seeds against free radical damage. Thus, medicinal pumpkin seed deterioration was closely related to decrease in the activities of free radical detoxifying enzymes and increased lipid peroxidation.

Keywords

• Antioxidant
• Ageing
• Germination
• electrical conductivity