METHODS OF EVALUATION FOR PREHARVEST SPROUTING RESISTANCE IN WHEAT BREEDING PROGRAMS

Mature wheat (Triticum spp.) kernels subjected to high moisture often incur preharvest sprouting damage. The experiments described here sought to evaluate two methods of measuring preharvest sprouting susceptibility, and to determine the environmental sensitivity of the methods, for use in selection and testing of sprouting-resistant wheat genotypes. Preharvest sprouting of eight hexaploid wheat (Triticum aestivum L. em Thell) lines was measured by artificial wetting of intact spikes, and by germination tests on threshed seed from each of four location near Ithaca, N. Y., in 3 consecutive years. The relative size of genotypic and nongenetic effects varied over the course of the experiments. At optimal measurement times, genotype accounted for over 40% of phenotypic variation, with another 20% attributed to environment and interactions. Effects of nongenetic factors were minimal when phenotypes were based on germination percent at day 4 or spike sprouting score at day 6. A storage technique previously reported to preserve dormancy was found effective for up to 3 mo, increasing the number of treatments that can be tested at comparable levels of dormancy. These data will be useful in planning basic investigations of preharvest sprouting resistance, and incorporating sprouting resistance testing procedures into wheat breeding programs.Key words: Wheat, preharvest sprouting, resistance, germination, dormancy, white kernel color