Search

This study aimed at evaluating the variability in resistance of common bean progenies and plants to diseases caused by Pseudocercospora griseola and Colletotrichum lindemuthianum. It also sought to infer whether S0 plants were heterozygous for the possible resistance loci and the frequency resistant plants varies with the bulk opening generation. Progenies from the fourteenth yield recurrent selection cycle were used. One hundred S2:7 and one hundred S5:9 progenies derived from ten S0:2 plants were evaluated. Seedlings were inoculated separately with the 63–63 race of P. griseola and race 65 of C.lindemuthianum. Variance analyses were conducted for disease severity scores and both the genotypic and phenotypic parameters were estimated. The progenies showed variable resistance levels to the disease caused by both pathogens. Such variability was detected among plants of the population and among descendants of some S0 plants, thus suggesting that they were likely heterozygous for the resistance loci. The frequency of resistant progenies/plants in the population was high, even though the selection was not specific these pathogens. The time of bulk opening did not significantly affect the reaction to the disease by both pathogen. This information is useful for future recurrent selection cycles.

The number of pods per common bean plant is a primary component of grain yield, which depends on the number of flowers produced and on the flower set. Thus, a larger number of flowers per plant would increase yield. Lines with inflorescences that had a large number of flowers compared to common bean plants now under cultivation were identified. We analyzed the genetic control of this trait and its association with grain yield. The cultivar BRSMG Talismã was crossed with 2 lines, L.59583 and L.59692, which have a large number of flowers. The F1, F2, and F3 generations were obtained. These generations were assessed together with the parents in a randomized block experimental design with 2 replications. The traits assessed included length of inflorescence, number of pods per inflorescence, number of pods per plant, number of grains per plant, 100-grain weight, and grain yield per plant. Mean genetic components and variance were estimated. The traits length of inflorescence and number of pods per inflorescence exhibited genetic control with predominance that showed an additive effect. In the 2 crosses, genetic control of grain yield and of its primary components showed that the allelic interaction of dominance was high. The wide variability in the traits assessed may be used to increase yield of the common bean plant by increasing the number of flowers on the plant.