Parâmetros genéticos da resistência ao nematoide das galhas em Phaseolus vulgaris L.

Abstract

Several factors affect the production of both snap bean and common bean in Brazil including the occurrence of nematodes of the genus Meloidogyne. Thus, the objective of this work was to investigate the genetic control of the resistance of the common bean M. incognita race 1, estimating genetic, phenotypic and environmental parameters that help in breeding programs aimed at incorporating resistance to the root-knot nematode. The experiment was implemented in a greenhouse, in the Olericulture sector of the Federal University of Lavras. Initially, crosses between the parents were carried out, Aporé (P1) resistant to the root-knot nematode and Bolinha (P2) susceptible to the nematode, in order to obtain the generation [F1 (P1 x P2)]. In the second stage of the work, the F2 generation [self-fertilization of F1 (P1 x P2)] was obtained. An evaluation was carried out regarding the resistance to the nematode M. incognita race 1 in the parents and generations F1 and F2. Forty days after inoculation with eggs of M. incognita race 1, the plants were evaluated for the number of total eggs per bean plant (NO), number of eggs per gram of root (NOGR), total reproduction index (IRT) reproduction index per gram of root (IRGR) and reproduction factor (FR). With the data obtained, the phenotypic, genetic and environmental variances were estimated; heritability in the broad sense at the level of the averages of the F2 generation; the coefficient of genetic variation, genetic, phenotypic and environmental correlations; selection gains and correlated response. It is concluded that the Aporé bean cultivar presents resistance to M. incognita race 1, and can be used as a source of resistance to the pathogen in breeding programs, both for common bean and for snap bean. It was also concluded that the characteristics of number of eggs per gram of root and reproduction index based on the number of eggs per gram of root are the most suitable for evaluation and selection for resistance to Melodogyne incognita in common bean and snap bean.