Herdabilidade e segregação de caracteres de importância econômica no pessegueiro

Abstract

The peach culture [Prunus persica (L.) Batsch] has been growing throughout the world, due to an increase in consumption of fresh fruits and processed products. Aiming the development of new productive and adapted cultivars, with good quality fruits and disease resistance, breeding programs are partially responsible for the expansion of the culture, in Brazil. The knowledge of the genetic, phenotypic and environmental parameters that influence, directly or indirectly, on the economically important characters in peach is of fundamental importance for the fruit breeding programs, allowing to anticipate the possibility of success with the selection of genotypes under different environments. The main objective of this work was to seek sources of brown rot resistant genotypes, as well as study the segregation, estimate the heritability and verify the possible existence of maternal effect on some characters of economic importance in peach. Phenotypic variability and transgressive segregation were observed for the phenological characters studied on the evaluated populations. The heritability of the fruit development period, date of full blooming and maturity date, is high to very high, allowing a rapid genetic gain for these phenological characters. The inheritance of the studied phenological characters is predominantly additive, and the deviations can be attributed to a possible maternal effect or major genes. It was observed the presence of transgressive segregation for the parameters relating to the tonality of flesh color (Hue angle, chroma and luminance), and the estimated heritability was high, enabling fast genetic advance for this character. The heritability of this character is predominantly additive, and the deviations can be attributed to the minor genes, without observing signs of maternal effects. The Hue angle is the correct parameter to classify and study the flesh color tonality of yellow peaches and nectarines. The luminance parameter may be an option for the study of white flesh. The use of the three parameters together, enables better representation of this character. For the character brown rot resistance on flowers and fruits, a high genetic variability was verified. The cultivars Maciel and Cerrito were the parentals with higher resistance to flower blight, and they transmitted this trait to their offspring. The selection Conserva 947 and selection Conserva 1600 were the parentals with higher brown rot resistance to infection on fruit, similar to ‘Bolinha’, passing this trait to their offspring. The heritability of brown rot resistance on flowers (incidence and severity) and fruits (diameter of the lesion and sporulation), in peach, is medium. Parental selection based on phenotype, enables a genetic breakthrough for medium resistance to brown rot.