Persistence of Reed Canarygrass Clones in Binary Mixture with Alfalfa and Birdsfoot Trefoil

Competitive exclusion of one component of a binary perennial grass‐legume mixture by the other component is common, but the persistence of both components is desired. Fourteen reed canarygrass ( Phalaris arundinacea L.) clones, exhibiting a range for drymatter yield (DMY), tiller density, and tiller weight, were grown in alternate‐plant binary mixture with ‘Olympic’ or ‘Baker’ alfalfa ( Medicago sativa L.) or ‘Norcen’ or ‘Dawn’ birdsfoot trefoil ( Lotus corniculatus L.) under a three‐cut‐per‐year management. The objectives were to determine if reed canarygrass clones and legume cultivars interact for DMY and legume concentration, to determine if the ranking of 14 reed canarygrass clones for legume concentration remained consistent across harvests, to compare the importance of tiller density and tiller weight to reed canarygrass DMY in legume mixtures, and to characterize the changing relationship between DMY of reed canarygrass and companion legumes over time. Alfalfa and birdsfoot trefoil concentrations increased from 266 and 159 g kg −1 , respectively, at Harvest 1 (8 June 1983), to 937 and 856 g kg −1 , respectively, at Harvest 7 (7 June 1985). Interaction between reed canarygrass clones and legume cultivars generally did not accompany significance of main effects, and ranks for legume concentration among reed canarygrass clonal mixtures stabilized by Harvest 2 (26 July 1983). Thus, it may be relatively easy to characterize reed canarygrass clones for legume compatibility. In mixtures, differences in tiller density among reed canarygrass clones usually accounted for more variation in reed canarygrass DMY than differences in tiller weight. A negative relationship between reed canarygrass DMY and legume DMY was always present. Though legumes increasingly dominated reed canarygrass over time, the rate of increase of their domination slowed as legume concentration increased.