A High-Throughput Characterization of Freezing Tolerance in Vicia Villosa for Northern Adaptation.

Vicia villosa, commonly referred to as hairy vetch, is a winter-annual legume that is increasingly gaining popularity as a cover-crop given the potential N contribution and accompanying ecosystem services. Although it is often cited as one of the most winter-hardy annual legume species available, successful overwintering is not guaranteed in northern temperate growing regions. Winter-hardiness is a complex trait that can require several years to accurately phenotype, given the uncontrollable nature of winter pressure and field variability. Muddling the scenario further, is a lack of defined varieties commercially available for the species. With the exception of some released varieties with southern adaptation, most available germplasm is designated as variety-not-stated. To efficiently characterize unstudied populations of V. villosa, we developed a method of controlled freezing in artificial conditions by testing a subset of accessions with known winter-hardiness from a multi-year evaluation across Minnesota locations. We found duration of cold acclimation and growth stage at the time of freezing to both significantly affect plant survival following freezing treatments. A single treatment, which was most reflective of field evaluations, was then applied to a larger germplasm set. Our results suggest that freezing tolerance in a controlled environment correlates highly with winter-hardiness from field evaluations and could therefore be utilized for phenotypic selection. The derived methodology offers an intuitive, low-cost, time-efficient, and controlled method for assessing the winter-hardiness potential of populations of V. villosa.