Structural mechanics of seed deterioration: Standing the test of time

Seeds die inevitably but unexpectedly during storage and current understanding of seed quality and storage conditions do not allow reliable means to predict or prevent this critical problem. Chemical degradation of seed components likely occurs through oxidative damage, but the rate of these reactions is dominated by properties of seed that are affected by temperature and moisture. These visco-elastic properties contribute to the structure of seeds as amorphous solids. This paper presents the perspective of seed maturation and post-harvest treatment as an exercise in engineering design for a structure that must persist through time and fluctuating conditions. Structural analyses are engineering tools used to select proper composition of materials and predict their behavior under a range of circumstances and are applicable to measurement within seeds. Thermal mechanical analysis (TMA) and dynamic mechanical analysis (DMA) measure structural deformation and stress–strain relationships, providing sensitive and universal parameters that detect differences in structural stability in materials with subtle compositional differences or processing methods. When applied to seeds, TMA and DMA techniques provide information consistent with existing information on glass and first order transitions. The depth of additional information obtainable about the behavior of the glass and interactions with lipid structure suggests that these techniques will be able to quantify differences among seed structures that contribute to their tendency to age.