XVI International Botanical Congess

A greenhouse evaluation method was developed to screen birdsfoot trefoil germplasm for resistance to Fusarium root rot. Twelve weeks after seeding, roots were cut and inoculated with a composite of fungal isolates. Ten weeks later, plants were scored for percentage of internal rot (IR) and length of vertical discoloration (VD) from the inoculation site. One cycle of bi-directional selection for reaction to F. oxysporum was conducted within cv. San Gabriel. The source and cycle-1 populations, and 2 Uruguayan and 3 North American germplasms varied for root rot reaction (IR range: 5.7-18.7%, VD range: 1.2-3.8 cm). The resistant cycle-1 population had significantly lower IR and VD scores than San Gabriel, indicating that breeding for resistance has the potential to limit Fusarium root rot.