Sprout damage and preharvest sprout resistance in hard white winter wheat

Increased production of hard white winter (HWW) wheat, Triticum aestivum L. , in the Great Plains introduces the possibility of preharvest sprouting (P HS) that is often not expressed among widely grown hard red winter (HRW) cu ltivars. Field experiments were conducted to learn the severity of sproutin g Likely to occur in contemporary HWW wheat. Specific objectives were to (i ) determine the level of sprout damage in Great Plains environments for HWW and HRW genotypes, (ii) assess the level of PHS resistance among the two c lasses, and (iii) determine the relative merits of germination tests and sp ike-wetting treatments. Twenty-four HWW experimental lines, three HWW culti vars, and five HRW cultivars were evaluated at Stillwater and Lahoma, OK, i n 1995 and 1996. Differences in sprout damage measured at two harvest dates were clearly evident between HRW and HWW entries. Pre-harvest sprout resis tance measured at physiological maturity varied widely among HWW lines. No line was as resistant as Plainsman V, a HRW cultivar previously not known t o possess high PHS resistance. Two lines were equivalent to the most resist ant HWW cultivar, Rio Blanco. Major genes for red kernel color did confer s ome protection from pre-harvest sprouting, but their absence did not preclu de useful levels of resistance. Chaff tissue played a minor role in influen cing genetic differences in resistance. Germination percent at physiologica l maturity was strongly correlated with field measurements of sprout damage and showed high repeatability. Future improvement of PHS resistance is nee ded in HWW wheat and should emphasize this component.