Vigor and Persistence of Birdsfoot Trefoil Populations Selected with or without an Orchardgrass Companion Evaluated in Grass Sod

Abstract

ABSTRACTForage legumes are often grown in mixtures with grass for grazing or harvested for hay or silage. Forage legume breeders often debate the necessity of incorporating grass competition into the breeding process, particularly when bred varieties will be used in mixture with grass. To address this debate, a two by two by two factorial of eight birdsfoot trefoil (Lotus corniculatus L.) populations were developed from selections of plants made at two nursery sites (Boone, IA, and Prairie du Sac, WI), out of two base cultivars (Norcen and WITT), and under two nursery treatments [orchardgrass (Dactylis glomerata L.) overseeded and no‐grass overseeded]. Space‐plants of the eight birdsfoot trefoil populations were transplanted directly into grass sod and evaluated for 4 yr for visual vigor (a proxy for biomass yield) and plant persistence. Persistence over time was measured using a linear model describing the decline in stand percentage per month. Overall, the four birdsfoot trefoil populations bred with a grass companion persisted better when transplanted into grass sod (slope −1.12% persistence mo−1) compared with the four birdsfoot trefoil population bred without a grass companion (slope −1.43% persistence mo−1). On average, only the WITT‐derived populations selected with a grass companion had superior visual vigor ratings when transplanted into sod compared with the WITT‐derived populations selected without a grass companion. This study provides evidence that selecting birdsfoot trefoil with an orchardgrass companion leads to more persistent birdsfoot trefoil varieties for use in grass mixtures compared with birdsfoot trefoil bred without a grass companion.