Evaluation of Common Bean (Phaseolus vulgaris) Genotypes for Resistance to Root Rot Disease Caused by Pythium aphanidermatum and Pythium splendens under Screen House

Abstract

The most important economic species of the genus Phaseolus is the common beans (Phaseolus vulgaris L.) which is widely cultivated and arguably the most significant leguminous for direct human consumption. It is an important source of dietary protein, calories, dietary fibres and minerals particularly iron and zinc. Root rot disease caused by Pythium pathogen is one of the major production constraint in bean growing areas within East Africa. In Tanzania, control measures used by farmers are fungicidal seed treatments which are less effective and not environmentally friendly, soil drainage and crop rotation which are not sustainable in the disease management. This study focused on the evaluation and selection of promising common bean genotypes for resistance to Pythium root rot disease from 100 bean genotypes sourced from Tanzania, CIAT and Andean Diversity Panel (ADP). Inoculum of Pythium aphanidermatum and Pythium splendens were used for challenging the beans genotypes under controlled environment. Experiment was set by randomized completely block design (RCBD) with three replications. Disease severity was assessed based on 1-9 scale; 1 being non-pathogenic and 9 being highly pathogenic. The response of common bean genotypes to P. aphanidermatum and P. splendens and their interactions were statistically different (P<0.0001). Two bean genotypes ADP-014 and ADP-080 showed promising trait of resistance, 38 genotypes showed moderate resistant trait and 57 were susceptible to Pythium root rot disease.

Keywords: Inoculum, Leguminous, Pathogenic, Resistant trait, Severity.