Evaluation of Methods Used in Testing Winter Wheat Susceptibility to Preharvest Sprouting1

Rains after wheat (Triticum aestivum L.) is physiologically ripe can cause preharvest sprouting which can lower the baking quality of flour due to de novo synthesis of alpha‐amylase. A fast, repeatable method is needed by plant breeders to screen wheat lines for their susceptibility to preharvest sprouting. In this study, three winter wheat cultivars varying in susceptibility to preharvest sprouting were grown in six different environments within the Pacific Northwest and were used to evaluate four germination and three enzymatic tests that measure sprouting susceptibility. Germination tests were performed with intact spikes and threshed seeds at four temperatures (15, 20, 25, and 30°C). Enzymatic tests were performed using flour milled from seeds that had been germinated at 15°C. The evaluation was based on 15 parameters of sprouting measured in the various tests. For a sprouting parameter to be considered a useful indicator of sprouting susceptibility it had to show significant (P < 0.05) differences in both cultivar and environmental effects at a given germination temperature, and its coefficient of variation had to be low. A germination test using intact spikes rolled in paper towels and one using threshed seeds in petri dishes at 20°C were the only tests that yielded parameters meeting the required criteria. Although disadvantages and advantages are associated with each of the parameters examined, germination tests were better in predicting sprouting susceptibility whereas enzymatic tests were better in quantifying actual sprout damage.