Outcrossing in Twelve Hard Red Winter Wheat Cultivars
Relative outcrossing (OC) rates with a mixture of awnless pollinators were determined for 12 hard red winter wheat (Triticum aestivum L.) cultivars during the crop years 1982 through 1984 at Hays, KS. Significant differences among cultivars were measured within years and averaged over years. The OC rate ranged from 0.1 to 5.6% for individual cultivars in a given year. The semidwarf experimental line, KS75210, and its sister selection, ‘Newton’, had the highest 3-yr average OC rate, 3.1 and 2.1%, respectively, whereas a standardheight cultivar, Centurk 78, had the lowest average OC rate, 0.3%. Semidwarf cultivars Vona and Wings were not significantly different from Centurk 78 in any year. The OC correlated positively with length of flowering period only in 1983; there was no significant correlation with either flowering data or plant height. Therefore, increased OC rate was not associated with semidwarf stature. Significant cultivar ✕ year interactions occurred. When the bulk samples were separated into seed-size fractions, several cultivars showed significant differences in OC rate within their fractions in one or more years. ‘Triumph 64’ was the only cultivar that had greater OC rate in the small-seed fraction than in the large-seed fraction when analyzed over years. When bulk samples were separated into highand low-density fractions on a gravity table, no significant OC-rate differences were found between fractions of the same cultivar within years or averaged over cultivars. Thus, mechanical separation of seed lots based on seed size or density did not consistently provide a means to reduce outcrossed seed in the seed source.
Copyright © 1990.