Genetically-Enhanced Winter-Hardy Faba Bean (Vicia faba L.) Germplasm for Cover Crop Cultivar Development.

Cover crop utilization in North American farming systems is expanding. In response to a recent surge in demand for diverse sources of cover crops, we are working on enhancing the winter-hardiness of faba bean (Vicia faba L.) for use as a winter leguminous cover crop. Faba bean is grown world-wide as a pulse (grain legume) crop and several studies have demonstrated a net N benefit (up to 100–200 kg N ha⁻¹) for the following crop in rotation. The USDA faba bean germplasm collection of ~800 accessions from 60 countries is maintained at the Western Regional Plant Introduction Station in Pullman, WA. This germplasm collection has captured a sufficient amount of genetic variation and contributed to our effort in enhancing winter-hardiness by using natural selection for over-wintering in southeastern Washington. We have recently released four winter-hardy faba bean germplasm lines after selection over five consecutive winter seasons for pulse and cover crop development in the U.S. Pacific Northwest and other regions up to USDA Plant Hardiness Zone 6b. Progress is being made in selecting for higher biomass yield and smaller seed size, important traits for economical use of faba bean as a cover crop. A new line with high yield potential (over 2,300 kg ha⁻¹) in two consecutive years and small seed size (0.4 grams seed⁻¹) is in the process of germplasm release for cover crop development.