SEASONAL FORAGE PRODUCTION AND REGROWTH OF HARD AND SOFT RED WINTER-WHEAT

The dual use of winter wheat (Triticum aestivum L.) for forage and grain throughout the southern Great Plains of the USA demands that breeding programs consider forage characteristics during cultivar development. This study was conducted to determine if the present pool of adapted cultivars provides enough variability in seasonal forage production and regrowth to allow future genetic improvement. Eighteen cultivars from two market classes, soft (SRW) and hard red winter (HRW), were evaluated in three environments. Long-term (seasonal) and short-term forage harvests (weekly regrowth following the long-term harvest) were scheduled in the fall and late winter to correspond to maximum forage growth. Soft and hard wheat classes did not differ in average long-term or short-term production in the fall. The SRW cultivars produced 30% more winter forage, but the HRW cultivars produced 26% more late winter regrowth than the SRW cultivars. Within-class differences were detected in both seasons, except for fall regrowth. Long-term winter production was not correlated with long-term fall production. Short-term forage regrowth was a linear function of accumulated growing degree-days. No significant relationship was found between long-term production and regrowth rate in the fall. In contrast, an inverse rank-order relationship (r = -0.53, df = 16, P less-than-or-equal-to 0.05) was found in the winter, where differences in regrowth rate were likely influenced by ontogeny. Soft and hard red winter cultivars appear equally suited as germplasm sources for genetic improvement of wheat forage capacity.