sumario v2n4.pmd

Abstract

ABSTRACT The genotypic variability of the resistance to Cercospora sojina can be used in breeding programs to develop soybean resistant cultivars. The characterization of progenitors and the genetic system involved allow the breeder to select the best progenitors, breeding method and selection procedure to be used. In this study a diallel of four soybean cultivars including the parents and all possible hybrids but the reciprocals were tested. Three resistant cultivars (Cristalina, Paraná and Uberaba) and a susceptible one (Bossier) and their F 1 populations were inoculated with the monosporic isolate identified as race 4. Results demonstrate that the resistance to C. sojina is controlled by a dominant gene or a gene-block; additive genetic effect and dominance are involved; the contribution of the environmental variation is minimum; and the interaction among the genes ranges from the partial to the complete dominance type, depending on the characteristic used in the evaluation of the resistance