Combining Ability of Binary Mixtures of Native, Warm‐Season Grasses and Legumes

Abstract

Growing complementary plant species is an alternative approach to enhancing pasture production. Our objective was to estimate combining ability for native, warm‐season grasses and legumes grown in binary mixtures in the field using a combining ability analysis of variance. Six monocultures and 15 binary mixtures of the following species were studied: big bluestem, Andropogon gerardii Vit.; Illinois bundleflower, Desmanthus illinoensis (Michx.) MacM.; roundhead lespedeza, Lespedeza capitata Michx.; slender lespedeza, L. virginica (L.) Britt.; switchgrass, Panicum virgatum L.; and indiangrass, Sorghastrum nutans (L.) Nash. General combining ability (GCA) effects were found for forage dry matter yields (DMY, P ≤ 0.05) of Illinois bundleflower (−1240 kg ha −1 ), roundhead lespedeza (−3460 kg ha −1 ), slender lespedeza (−3300 kg ha −1 ), and switchgrass (8370 kg ha −1 ). Specific combining ability (SCA) effects were found for DMY ( P ≤ 0.1) of switchgrass‐legume mixtures (1360 kg ha −1 ) and indiangrass‐Illinois bundleflower mixtures (1230 kg ha −1 ). General combining ability and SCA effects were found for crude protein concentration (CPC) of all species and mixtures ( P ≤ 0.1), respectively. General combining ability effects were found for in vitro dry matter digestibility (IVDMD) for switchgrass and the three legume species ( P ≤ 0.05). The compatibility of these species could not be predicted solely by DMYs. Compatible mixtures, however, were identified with greater confidence when other variables, such as CPC, IVDMD, and visual observations, were taken into account. On the basis of total forage protein (DMY times CPC), the only compatible grass‐legume mixture was indiangrass‐Illinois bundleflower (SCA effect = 100 kg ha −1 , P ≤ 0.05).