Preharvest Sprouting Tolerance in Current Soft Red Winter Wheat Cultivars

Preharvest sprouting (PHS) results in unacceptable flour quality for a portion of the mid-Atlantic soft red winter wheat (SRWW) (Triticum aestivum L) crop annually. This research evaluates inherent dormancy in current mid-Atlantic wheat cultivars using grain falling number after delayed harvest and the weighted germination index (WGI) to predict PHS. Individual spikes from 15 wheat cultivars grown in Virginia in 2007 and 2008 were harvested at physiological maturity and seeds germinated under controlled conditions. A WGI was calculated that gave greater weight to cultivars with seeds that germinated more quickly. The WGI effectively identified very high and low dormancy SRWW cultivars; however, the influence of environment during grain fill was important, especially for cultivars with moderate dormancy. To evaluate PHS tolerance by line under natural conditions, plots were left standing up to 6 wk after normal harvest date. Final harvest falling numbers were used to separate cultivars into PHS resistance groups. Strong relationships were found among PHS resistance groups, and WGI was determined at both 10 and 30 degrees C. This indicates that PHS resistance groups were good predictors of dormancy and relative response of cultivars to delayed harvest. The morphological characteristics of head angle, glume tenacity, and awn length had no significant effect on PHS. Artificial wetting resulted in a major loss of quality after just one event, emphasizing the need for timely wheat harvest.