Estratégias de seleção em progenies de meios-irmãos em Annona squamosa L.

Abstract

The Brazil stands out as one of the great fruit producers in the world, the production of sugar apple (Annona squamosa L.) has been leveraged in the country mainly due to the attractive prices achieved by the fruit in the market and the plants' ability to tolerate different edaphoclimatic conditions. Few studies on genetic diversity and genetic improvement involving the crop have been published. In Brazil, the availability of improved materials of A. squamosa for cultivation is restricted to some selections and there are no registered varieties for planting in the country. In this context, the first part of the work aimed to estimate the genetic parameters, correlations and predictions of direct, indirect and simultaneous selection gains in half-sib progenies of Annona squamosa L. Therefore, they were evaluated in four half sib progenies. siblings, during eight harvests, the characteristics mean number of flowers (NF), mean length of flowers (CF), number of fruits (NFr), mean length of fruits (CFr), mean diameter of fruits (DFr), fresh weight of fruits (MFFr), number of seeds (NS) and total production (PT). High magnitude heritability was attributed to CF, 66%, while moderate heritability was found to NF (21%), NS (25%), CFr (29%), DFr (33%) and MFFr (42%). NFr and PT, on the other hand, expressed low magnitude heritability, 0.3% and 8%, respectively. There was a positive correlation between total production and number of fruits/plant. Flower length also showed a strong correlation with characteristics related to fruit size. The flower number characteristic expressed the highest estimates of direct selection gains. The genotypes 25 (UNI-1), 10 and 47 (UNI-2) and 11 (UNI-3) stood out, presenting high estimates for more than one trait and should be considered for selection. The second part of the work aimed to evaluate the repeated measures over eight harvests to estimate the repeatability coefficient and the ideal number of measures to be considered in the selection of superior genotypes of A. squamosa L. The characteristics NF, CF, CFr, DFr, MFFr, NS and PT were evaluated during eight harvests. It was observed that five measurements/crops is an adequate number for the selection of superior genotypes, and that these evaluations should be carried out, preferably, between the fourth and sixth year after planting. Thus, the results presented allow the breeder to continue with new stages of the genetic improvement process of the species in a safe way.