Comparison of inoculation methods for selecting common bean genotypes with physiological resistance to white mold

Abstract

Although different methods of inoculation have been proposed to assess the reaction of common bean to white mold (WM) caused by Sclerotinia sclerotiorum, a thorough comparison among them is lacking. In this study, six approaches were tested to identify the most reproducible and efficient method for discriminating six common bean genotypes of carioca market class based on their resistance to white mold. These included: modified straw test (ST), cotton pad (CP), infected flower on intact plant (IFIP) or on detached leaf (IFDL), and mycelium disc on intact plant (MDIP) or on detached leaf (MDDL). All experiments were conducted in a greenhouse or laboratory in a completely randomized design with four replicates. Several statistics including coefficient of variation (CV), standard deviation, intraclass correlation coefficient (ICC), p value for Bartlett’s test for homoscedasticity and sensitivity ratio (SR) were used as criteria for discrimination. The Spearman’s correlation coefficient was used to test the association between the methods. Results showed ST as the most suitable for selecting WM-resistant genotypes, followed by the IFIP method.