Role of sorption properties and water status in control of seed longevity patterns

The longevity behaviour of two oil-rich seeds, soybean (Glycine max (L.) Merrill) and safflower (Carthamus tinctorius) were compared using their water absorption properties. The nuclear magnetic resonance characterization of water in different moisture equilibrated seeds was studied in relation to the viability of both the crops. The component analysis of the transverse relaxation showed the presence of different components in soybean and safflower at corresponding relative humidity. Even though a more deleterious third component (structurally bound water) was observed at higher relative humidity in both the crops, the difference in its relative population clearly shows the linkage between molecular mobility of water and longevity. The dehydration and rehydration isotherms studied under the ambient relative humidity pointed towards the possible development of extra polar sites in soybean along with the varied behaviour of these two seeds under fluctuating relative humidity conditions, which is a common phenomenon in ambient storage conditions. Thus, the present study emphasizes that the sorption properties along with the structural partitioning of the seed water, which are influenced by the chemical composition of seed, play an important role in the longevity behaviour of seeds besides other factors like lipid peroxidation.