Genetic control of soybean resistance to brown spot (Septoria glycines): first studies
Rodrigo Luis Brogin; Carlos Alberto Arrabal Arias and José Francisco Ferraz de Toledo
Knowledge of the genetic effects that control a trait is essential to direct the breeding program for gains in the selection process. The main objective of this study was to investigate the genetic control of soybean resistance to brown spot. Two tolerant cultivars (FT-2 and Dourados) and two susceptible cultivars (Davis and Paraná) and the segregant F2 and F3 generations derived from the crosses between these cultivars were assessed for reaction to the disease after inoculation. Genetic models were adjusted to the means and variances of the generations. It could be concluded that the trait is governed by various genes with lesser effect, has low to medium heritability and selection should be made always using progeny from the F3 generation and can be made during the initial stages of soybean growth, based on the mean of at least two trifoliate leaves.