Genetic divergence in snap bean based on agronomic traits and resistance to bacterial wilt
Willian Krause; Rosana Rodrigues; Leandro Simões Azeredo Gonçalves; Francisco Valdevino Bezerra Neto and Nilton Rocha Leal
Abstract: The objectives of this research were to estimate the genetic divergence among genotypes of bush snap bean with based on morphoagronomic descriptors and evaluation of resistance to bacterial wilt; to determine the relative importance of the distinguishing traits of genotypes and to indicate potential parents to establish a snap bean breeding program for resistance to bacterial wilt. Two experiments were conducted, the first in the field and the secon in a greenhouse, both with 15 genotypes in a randomized block design with three replications. Seven traits were studied in the field experiment: days to flowering; days to harvest; mean pod length; number of pods; number of pods per plant; total pod weight and number of seeds per pod. In the greenhouse, the reaction of bacterial wilt was assessed based on two variables, one based on a descriptive grade scale and the other based on the Area Under the Disease Progress Curve (AUDPC). For the evaluation of genotype resistance to bacterial wilt the isolate Feij — 2634 of Curtobacterium flaccumfaciens pv. flaccumfaciens was inoculated. The statistics of pseudo t2 indicated the formation of four groups by the UPGMA method, the same number of groups as indicated by the use of canonical variables. The traits that contributed most to genetic divergence were days to harvest, pod length, pod diameter and AUDPC.