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Forage yield and quality of corn cultivars developed in different eras

Lauer, J.G., Coors, J.G., Flannery, P.J.
Crop science 2001 v.41 no.5 pp. 1449-1455
Zea mays, cultivars, temporal variation, corn stover, forage, yields, nutritive value, crop quality, early development, crude protein, fiber content, in vitro digestibility, Wisconsin
Gains in corn (Zea mays L.) grain yield over time are well documented, but corresponding changes in forage and stover yield and quality have received less attention. Our objective was to describe yield and quality changes of representative cultivars used by farmers in the northern Corn Belt. Six open-pollinated cultivars used prior to 1930, 24 cultivars representing four 15-yr eras between 1931 and 1990, and six modern cultivars, for a total of 36 cultivars, were divided into early- and late-maturity trials. Each trial was grown at three locations in Wisconsin during 1997 and 1998. Since 1930, corn forage dry matter yield has increased at the rate of 0.128 to 0.164 Mg ha(-1) yr(-1) with stover dry matter yields increasing at the rate of 0.043 to 0.054 Mg ha(-1) yr(-1). Forage crude protein has not changed significantly with time. Forage neutral detergent fiber concentration has decreased 0.825 to 0.948 g kg(-1) yr(-1), while forage in vitro digestibility increased 0.538 to 0.612 g kg(-1) yr(-1). Stover neutral detergent fiber concentration and in vitro digestibility have not changed over time. Since 1930 forage, stover, and ear yield have increased 1.4, 0.7, and 2.4% yr(-1), respectively. This trend will no doubt continue, but greater progress might be made if corn forage breeding improvement concentrates on yield and quality changes in stover.