Seed aging and viability are affected by a number of factors during seed production, as well as seed storage. The speed at which the seed aging process takes place depends on the seed’s ability to resist degradative changes as well as on its protection mechanisms, which are species-specific. Duration of aging period, type of storage and characteristics of species affected the degree of seed damage. The characteristics of the chemical composition of oil crops (soybean and sunflower) are related to specific processes occurring in seed during storage. Lipid auto-oxidation and increase of free fatty acid content during storage are the most often mentioned reasons for accelerated damage of seed of oily plant species. Vigour testing becomes more important in seeds stored under unknown or adverse storage conditions. Seed vigour can be viewed as a measure of accumulated damage in seed as viability declines. Regardless of the problems which can be encountered due to the lack of space with favourable conditions, one must always keep in mind that seed is a living organism in which many biological processes, which can damage the seed and reduce its quality, take place, especially when the oily seed is in question.
Fatty acids found in seed have been used as the seed quality indicator for many years. Intensified activities of enzymes that participate in lipid metabolism, caused especially by increased moisture content in seed and higher storage temperature, increased the usage of lipids in the respiration process, leading to significant reduction of oil content in seed. The types of fatty acids present in an oil, and in particular their number of double bounds, determine the type and extent of chemical reactions which occur during the storage time. In the majority of plant species having oil rich seeds the lipids that are at risk of auto-oxidation contain oleic (18:1), linoleic (18:2) and linolenic (18:1) fatty acid chain. Degree of unsaturation has a significant influence on degree of degradation.
Many authors emphasized the connection between length and conditions of storage and changes of fatty acid and oil content in seed.