Change in Fatty Acid Content of Polar Lipids during Ageing of Seeds of Peanut (Arachis hypogea L.)

Abstract

Seeds of two cultivars of peanuts (Arachis hypogea L.) were harvested in different seasons and stored in 5 °C for different periods (2 and 38 months). The seeds stored for the longer period had a lower germination, leached more electrically conducting material when soaked in distilled water for 24 h, and had lower contents of fatty acids in polar lipid fractions. The fatty acid compositions of neutral lipid, glycolipid, and phospholipid fractions were similar in the differently aged seeds. Hydroperoxides could not be detected. Seeds of one cultivar were rapidly aged in an environment of 38 °C and 90% relative humidity. During 28 d, germination fell from 95% to 15%, leaching of electrically conducting material increased about 5-fold, and the content of fatty acids in polar lipid fractions fell to almost 10% of the original. The negative relationship between leaching and germination approximated closely to a straight line. Most of the decline in content of fatty acids from polar lipids preceded most of the change in germination and leaching. The fatty acid compositions of the different lipid fractions were almost unchanged. This, together with the actual fatty acid compositions, proved that some factor other than peroxidation was involved in the lipid deterioration, and peroxidation was probably unimportant. Loss of control over subcellular compartmentation or intracellular concentrations of metabolites, resulting from loss of membrane lipids, may have been the cause of the loss of viability.