Genetic divergence in snap bean based on agronomic traits and resistance to bacterial wilt

Abstract

The objectives of this research were to estimate the genetic divergence among genotypes of bush snap beanwith based on morphoagronomic descriptors and evaluation of resistance to bacterial wilt; to determine the relative importanceof the distinguishing traits of genotypes and to indicate potential parents to establish a snap bean breeding program forresistance to bacterial wilt. Two experiments were conducted, the first in the field and the second in a greenhouse, both with 15genotypes in a randomized block design with three replications. Seven traits were studied in the field experiment: days toflowering; days to harvest; mean pod length; number of pods; number of pods per plant; total pod weight and number of seedsper pod. In the greenhouse, the reaction of bacterial wilt was assessed based on two variables, one based on a descriptivegrade scale and the other based on the Area Under the Disease Progress Curve (AUDPC). For the evaluation of genotyperesistance to bacterial wilt the isolate Feij – 2634 of Curtobacterium flaccumfaciens pv. flaccumfaciens was inoculated. Thestatistics of pseudo t2 indicated the formation of four groups by the UPGMA method, the same number of groups as indicatedby the use of canonical variables. The traits that contributed most to genetic divergence were days to harvest, pod length, poddiameter and AUDPC.

Keywords

• Curtobacterium flaccumfaciens pv. flaccumfaciens
• Phaseolus vulgaris L.
• genetic resistance
• germplasm
• pseudo F and