Performance of Orchardgrass, Smooth Bromegrass, and Ryegrass in Binary Mixtures with Alfalfa

Abstract Forage grass cultivars used in grass‐alfalfa (Medicago sativa L.) mixtures are generally the same as those used in pure stands. Little is known about the relative performance of grass cultivars in grass‐alfalfa mixtures in temperate North America. The objective of this study was to evaluate 78 cultivars and experimental populations of three species—orchardgrass (O), Dactylis glomerata L.; smooth bromegrass (SB), Bromus inermis Leyss.; and ryegrass (R), Lolium perenne L. and L. hybridum Hausskn.—for persistence and competitive ability in binary mixtures with alfalfa. Entries were seeded in 3‐m single‐row plots, spaced 0.9 m apart, in six randomized complete blocks at Arlington, WI, and overseeded with ‘Saranac’ alfalfa in April 1983. Plots were managed for 3 yr following the seeding year by taking three cuttings at late bud to early flower of alfalfa before 1 September. Species rankings for vigor and ground cover were O > SB > R; rankings for regrowth after cutting were O > R > SB. Orchardgrass increased in ground cover in each year, SB decreased in the first year and increased in subsequent years, while R decreased in the first year and remained nearly constant for the duration of the study. True ground cover ratings (TGC, expressed as a percentage of initial established stands) ranged from 46 to 508% for O, 31 to 233% for SB, and 21 to 81% for R. Cultivar variation for TGC was related to maturity in O, prior selection history in SB, and ploidy and species in R. Variation among entries was generally not related to performance in pure stands. The study provided an efficient procedure for developing preliminary evaluations of cultivars and experimental populations in mixture with alfalfa.