Identification of resistance sources to witches'broom disease - cacao germplasm evaluation. In: Agrotrópica v. 34 n. 3 p. 169-180, 2022.

Abstract

This work is part of the first studies that came to guide the recurrent selection processes for the association of resistance genes conducted by the Cacao Research Center, at Ilhéus, Bahia. Aiming to identify sources of witches’ broom disease resistance, a set of 573 accessions from the Cacao Germplasm Collection of this Center were evaluated for the variables number of vegetative brooms (VB), floral cushion brooms (CB), and total brooms (TB). In addition, the relationship between the per se performance of the accession and their general combining ability was analyzed using data of eight progenies trials, evaluated during several years. The lowest values for VB, CB and TB were observed in Scavina clones and descendants, Amazonian groups, and groups including materials selected for resistance. This study indicated ample possibilities of genetic gain and the occurrence of different resistance genes in the species. Also, indicated evolution of the pathogen, increasing its virulence over resistant materials, and the possibility of predicting the performance of progenies from their parent performances when the differences among them are large.