New faba bean genotypes resistant to chocolate spot caused by «Botrytis fabae»

Abstract

The response of sixty-seven genotypes of faba bean (Vicia faba) to the virulent isolate IBf24 of Botrytis fabae was studied under field conditions. Five of these genotypes (LPF39, LPF113, LPF44, LPF237 and LPF05) were moderately resistant to chocolate spot according to their MDI (mass disease index). Ten lines (LPF38, LPF41, LPF64, LPF95, LPF106, LPF132, LPF225, LPF228, LPF23, LPF233) were moderately susceptible, and fifteen lines (LPF54, LPF61, LPF66, LPF89, LPF124, LPF129, LPF131, LPF134, LPF138, LPF152, LPF173, LPF174, LPF190, LPF274, BPL710) susceptible as shown by their MDI values but with low AUDPC (area under disease progress curve) values and were believed to have an overall tolerance to the disease. Fourteen of the genotypes tested in the field, as well as the resistant BPL710 and the susceptible Rebaya 40 controls, were further screened under greenhouse conditions in order to confirm the field evaluation. In both the field and the greenhouse trials, the four lines LPF44, LPF237, LPF05 and LPF113 showed the highest level of resistance to the disease. These trials also revealed that genotypes with only overall tolerance may yet constitute interesting sources of resistance. Genotype BPL710, with known resistance to B. fabae races in the Mediterranean region, was found to be susceptible in the field but moderately susceptible in the greenhouse, suggesting the appearance of new races of this pathogen.