Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 2, 2000
Publication Date: October 1, 2001
Interpretive Summary: Producers need information on the ability of cool- and warm- season species to coexist and thrive together. These combining abilities are important for species presently grown or those having the potential of being grown for forage. We investigated the combining ability effect of growing native, warm-season grasses with native, warm-season legumes in binary (1:1) mixtures using a diallel analysis of variance. The species studied were big bluestem, Illinois bundleflower, roundhead lespedeza, slender lespedeza, switchgrass, and indiangrass. Dry matter yield alone was not enough to predict the compatibility of these species groups. Other factors, such as crude protein concentration, in vitro digestibility, and visual observation, can help identify compatible species. Under the conditions of this experiment, a mixture of indiangrass-Illinois bundleflower was superior to other grass-legume mixtures, while big bluestem-Illinois bundleflower was inferior to other mixtures.
Technical Abstract: Growing complementary plant species is an alternate approach to enhancing pasture production. Our objective was to estimate combining ability for various native warm-season grasses and legumes grown in binary mixtures in the field using a diallel analysis of variance. Species studied were big bluestem, Illinois bundleflower, roundhead lespedeza, slender lespedeza, switchgrass, and indiangrass. Significant (P<0.05) general combining ability (GCA) effects were found for forage dry matter yield for Illinois bundleflower (-1,232 kg/ha), roundhead lespedeza (-3,453 kg/ha), slender lespedeza (-3,298 kg/ha) and for switchgrass (8,369 kg/ha). Significant specific combining ability (SCA) effects were found for switchgrass-legume mixtures (1,358 kg/ha) and for indiangrass-Illinois bundleflower mixtures (1,225 kg/ha). Significant GCA and SCA effects were found for crude protein concentration (CPC) and in vitro dry matter digestibility (IVDMD). GCA effects for CPC were shown for all species and averaged from -29.6 g/kg for switchgrass to 37.5 g/kg for Illinois bundleflower. SCA effects for CPC were significant for all species combinations. Among grass-legume mixtures, SCA effects for CPC were all negative and averaged -12.8 g/kg. GCA effects for IVDMD averaged from -41.3 g/kg for switchgrass to 18.1 g/kg for slender lespedeza. We found that DM yield alone was not enough to predict compatibility. Other variables, such as CPC and IVDMD helped identify compatible species. Under these experimental conditions, a mixture of indiangrass-Illinois bundleflower was superior to other mixtures.