Crimson Clover Accessions Trial.

Cash crop cultivar improvement has been instrumental in long-term economic and agronomic performance for growers. Corn and soybean breeding efforts have created high performing, regionally adapted cultivars. In comparison, there has been far less effort expended to select and develop cover crop cultivars. Crimson clover is the most widely used legume cover crop in the United States (U.S.), yet growers have few options to select crimson clover cultivars suited to their climate, soil, and cropping system goals. We conducted a survey where farmers identified legume cover crop biological nitrogen fixation, biomass, winter hardiness, and maturity timing as key traits of interest. Efforts to improve cover crop genetics will not only increase the productivity of farms which already utilize them, but could encourage the adoption of cover crops by other growers. In this study, we assessed trait differences among 30 crimson clover accessions at two East Coast U.S. sites (cold and moderate climates). There were significant differences in biomass, winter hardiness, biological nitrogen fixation, and flowering time among the 30 accessions. Moreover, individual accessions showed differences in the nodule symbiotic bacterial community as determined by metagenomic sequencing. Contributing to the improvement of cover crop germplasm, this research provides foundational knowledge for future cover crop breeding programs.