Objective:
The objectives of this cooperative research project are: 1) confirm identified seed longevity traits for accessions of rye, wheat, and triticale and Secale landraces; 2) Correlate phenological and morphological traits, seed composition, and biophysical parameters with measured longevity; 3) Measure compositional changes in seeds as they deteriorate; 4) Correlate viability loss of stored seeds with field emergence; 5) Estimate the temperature sensitivity of different phases of seed deterioration time course among accessions.

Approach:
This research is intended to identify differential responses of genetic lines of rye, wheat, and triticale to dry and humid storage conditions and to determine whether genetic control of seed aging is expressed during the early stages of aging when deterioration is asymptomatic or the latter stages when seed viability declines rapidly. Traits hypothesized to influence shelf life will be measured to support a ¿candidate gene¿ approach to seed quality factors. Potential future studies of seed quality factors using a QTL approach will be enhanced by identification of parental lines with consistent responses to dry and humid conditions. Average seed longevity and variation among accessions and storage humidity was measured in a previous cooperative project, and the study here will build from those data by confirming accession tendencies for long and short shelf life and whether the pattern in which deterioration is expressed varies among cultivar (i.e., do cultivars have a long asymptomatic phase followed by an abrupt loss of viability or do they demonstrate a steady loss in viability during storage?). The basic experimental design will involve storage experiments under warm conditions (~35C) and varied relative humidity. Subsets of seeds will be removed at appropriate intervals and placed in the freezer to determine if the progress of deterioration can be slowed or stopped and whether this trait is under genetic control. We will use accessions identified from the previous project that were recently harvested as a confirmatory test of the stability of longevity characteristics among genetic lines. Biochemical and physical attributes that have been suggested in the literature to influence seed longevity will be measured in these freshly harvested seeds. The assays will include lipid and fatty acid content, storage protein, heat soluble protein, sugar and antioxidant levels, respiratory activity, water permeability, and water content-RH-temperature relationships. Biochemical and physical attributes will also be monitored during storage to determine the extent of peroxidation, protein carbonylation, and alteration of mechanical properties. The relationship between laboratory and field performance will be assessed with yearly field plantings of stored seeds.