Effect of oxalic acid on common bean progenies derived from recurrent selection for white mold resistance

Abstract

White mold is an important disease of common bean mainly under mild temperatures and high humidity, like in the irrigated cultures in the winter of Brazil.The main measure for controlling the disease is chemical, although it is not fully efficient and resistant cultivars would be the ideal for the farmers. However, the level of resistance of the available cultivars is low and it needs to be improved for being efficient for controlling the disease. The genetic control of the white mold resistance in common bean is quantitative with a considerable influence of the environment. Therefore, we have used recurrent selection for obtaining progenies with physiological resistance using the straw test procedure for evaluation. Another way of accessing the white mold resistance is through the evaluation of genotypes in oxalic acid solution (Kolkman & Kelly, 2000), and according to Carvalho et al. (2013) the evaluations obtained by straw test and by oxalic acid presented low correlation, and different genes of resistance can be acting. Therefore, aiming to improve the level of resistance, the selected progenies were also evaluated in a solution of oxalic acid, considering that plants more tolerant to this acid may have additional resistance.