Genetic Variation of Seed Dormancy in Synthetic Hexaploid Wheat-Derived Populations

Aegilops tauschii, the D genome donor of wheat (Triticum aestivum L.), has strong seed dormancy and genes controlling the trait may be used to improve resistance of cultivars to pre-harvest sprouting (PHS). Thus, this research project was initiated to identify dormancy genes from Ae. tauschii-derived synthetic hexaploid wheat (SHW) Four permanent segregating populations, developed by crossing four SHW lines with a common wheat line, were grown under field conditions to evaluate dormancy with threshed seeds (kernels) and/or intact seeds on the spike from 2006 to 2008. Significant genotypic and year effects on both kernel and on-spike seed dormancy were detected in each population, with heritability estimates of about 0.4 (0.32-0.48) across the years. Seeds on the spikes were much more dormant than kernels, suggesting the presence of germination inhibitors in the covering tissues. Significant correlations between kernel and on-spike seed germination percentages were detected in all populations; the estimated correlation coefficient (r) was greater for genotypic (0 80) than for phenotypic (0.63) or environmental (0.51) components. Thus, available SHW lines could be an alternative source of dormancy genes for enhancing resistance of wheat cultivars to PHS.