Wisconsin Grazing Composite (WGRCOMP)

Population Development and Selection

The Wisconsin Grazing Composite (WGRCOMP) is an open-pollinated population of corn that has unique potential as a forage because it contains two genes conditioning nutritional quality and regrowth after cutting, brown midrib3 (bm3) and grassy tillers1 (gt1). The bm3 gene is a low-lignin gene that elevates fiber digestibility. The gt1 gene increases the number of tillers produced by each plant, and thereby allows regrowth after cutting. WGRCOMP was developed by first backcrossing bm3 and gt1 into three inbred lines, W64A, W182BN, W117. The converted inbreds were then intermated to form a narrow-based base population for selection. The base population has undergone two cycles of mass selection for regrowth potential. Each selection cycle involved cutting, in mid-June, one thousand or more plants expressing both the bm3 and gt1 genes to approximately 2 inches in height from the ground. Those plants with the most vigorous regrowth were then selected and intermated to create the population for the next cycle of selection.