ESTIMATES OF GENETIC PARAMETERS OF LATE SEED-COAT DARKENING OF CARIOCA TYPE DRY BEANS Estimativas de parâmetros genéticos do caráter escurecimento tardio dos grãos de feijão carioca

In order to facilitate commercialization of cultivars of carioca type dry beans, the grains must have the lightest possible cream color and this phenotype must be persistent (late seed-coat darkening). There are reports of genetic variability for this trait. The objectives of this study were to obtain information regarding genetic control of the trait, with emphasis on the estimate of heritability and if it varies according to days after harvest, to verify the effect of locations and/or crop season on seed-coat darkening of the grains and to estimate the genetic and phenotypic correlations of the trait with cooking time, tannin content and grain yield. F2:3 and F2:4 progenies derived from crossing of the cultivar BRSMG Madrepérola (late seed-coat darkening) and the line RP-2 (early seed-coat darkening) were used. It is concluded that seed-coat darkening is influenced by the environment, crop season or locations; nevertheless, the interaction progenies x environments and progenies x locations is predominantly simple, not expressively changing classification of the progenies. Although the heritability of the darkening scores tends to increase with the storage time of the grain, the interaction progenies x time periods of assessment was not observed. Grains with late seed-coat darkening present a lower tannin content and require less cooking time. The genetic correlation between a dark seed-coat and grain yield was practically null.