Identification and multi-environment validation of resistance to Ascochyta fabae in faba bean (Vicia faba)

Ascochyta blight incited by Ascochyta fabae is a widespread disease severely damaging faba bean (Vicia faba) production. Insufficient resistance is available in faba bean cultivars. In an attempt to identify new sources of resistance a germplasm collection of 484 V. faba accessions was screened for resistance to A. fabae under field conditions; stability of resistance of the 19 most resistant accessions was tested in a multi-location experiment in Czech Republic, Estonia, Germany and Spain over two field seasons. Although complete resistance was not found, six accessions showed interesting levels of incomplete resistance. Genotype × environment (G × E) interaction accounted for 42% of the sum of squares of the multi-environment evaluation, revealing instability of the phenotypic expression across environments. Accessions L-831818, V-26 and V-958 stand out for their consistent resistance, being the most resistant and stable across environments. Accessions V-255, V-1020, V-1085 and V-1117 displayed good resistance, but lower stability, with V-1020, V-1085 and V-1117 being more suitable for Córdoba (Mediterranean mega-environment), and V-255 more suitable for Hohenlieth, Jõgeva and Sumperk (Continental mega-environment).

► Additional sources of resistance against Ascochyta fabae have been identified under field conditions in a germplasm collection of Vicia faba accessions. ► Genotype × environment (G × E) interaction accounted for 42% of the sum of squares of the multi-environment evaluation, revealing instability of the phenotypic expression across environments. ► Accessions L-831818, V-26 and V-958 stand out for their consistent resistance, being the most resistant and stable across environments.