Understanding the mechanisms and kinetics of seed aging

Abstract

When seeds deteriorate, they lose vigour and become more sensitive to stresses upon germination. Eventually seeds lose the ability to germinate. The factors which determine the rate of this ‘aging’ are the temperature and moisture content at which seeds are stored and an ill-defined parameter, seed quality. While it has been known for many years that manipulation of these factors influences the longevity of seeds, the precise interactions among them are so poorly understood as to preclude the prediction of longevity for a particular seed lot. Concepts from studies of materials and food stability can be applied to seed aging research, and this may help us take a more integrative approach to understanding the kinetics of seed deterioration. These concepts describe the physical environment of the seed matrix in response to changing water contents and temperature. Water activity models describe the state of water in the seed, while the glass models describe the state of the aqueous solution. Both models presume that changes of state affect the nature and kinetics of chemical reactions. Thus, the physical and chemical environment within the seed are inextricably linked.

Single-seed oxygen consumption measurements and population-based threshold models link respiration and germination rates under diverse conditions

“…A particularly attractive application would be to indicate the potential longevity of Population analysis of single-seed oxygen consumption 215 seed lots for germplasm conservation. Seed populations generally exhibit an extended period of high viability in storage, followed by a relatively rapid loss of viability (Walters, 1998). The length of the initial period of high viability varies among seed lots and is largely unpredictable, resulting in frequent testing, using up stored seed samples and resulting in the need for expensive regeneration, even if sample viability still remained high (Walters et al, 2005).…”

Physiological quality of coffee seeds produced under different levels of solar radiation and maturation stages

“…These seeds, however, also presented the worst physiological performance, i.e., highest deterioration; so a higher activity of this antioxidant enzyme would be then the expected. However, after an extensive literature review and in a study on the events causing seed deterioration, Walters (1998) and McDonald (1999) have found many references on the enzymatic activity of superoxide dismutase enzyme either for reduction or increase of its activity with the seed deterioration process.…”

“…According to Walters (1998) andMcDonald (1999) the lowest activity of such enzyme is related to events of seed deterioration. In this study, large differences in the electrophoresis analysis of the esterase isoenzymes among seeds produced under the different levels of solar radiation were not observed.…”

Storage on the vigor and viability of macauba seeds from two provenances of Minas Gerais State

“…Considering that macauba seeds have a high oil content (HIANE et al, 2005), reduction in seed moisture content are the most suitable method to assure a proper storage (VERTUCCI & ROOS, 1990). Failure in this step can increase the degradation rate of storage reserves in seeds and diminish their physiological quality during storage (WALTERS, 1998). The increase in macauba seed germination and GSI values, along with the storage period, may be related to the overcoming of dormancy.…”