NOTE - Minimum number of common bean plants per plot to assess field resistance to white mold

Abstract

This study aimed to determine the minimum number of plants per plot to assess the field resistance in common beanto white mold. Thirteen cultivars were inoculated with six isolates of Sclerotinia sclerotiorum and evaluated in a randomized blockdesign with three replications and plots consisting of 1-m rows with 15 plants. Plants were inoculated by the straw test as proposedby Petzoldt and Dickson (1996), to evaluate partial resistance in a greenhouse. Eight days after inoculation the disease severity wasevaluated on a 1-9 diagrammatic scale, where 1 = asymptomatic plants to 9 = plant death. To determine the minimum number ofplants per plot, the following methods were used: maximum curvature, segmented linear model, quadratic segmented model and therelative CV model. There were significant differences among cultivars and isolates and no significant cultivar - isolate interaction.It was observed that eight plants per plot is an adequate number to assess the reaction of common bean to white mold.

Keywords

• breeding
• Sclerotinia sclerotiorum
• experimental design
• resistance to the pathogen.