The objective of this work was to compare fruit weight and length of cycle, among cultivars of plum and peach, besides estimating the repeatability and determination coefficients and the number of measurements, for a safe prediction of these characteristics, and to compare different methods to estimate the repeatability. The traits were evaluated in 5 productive cycle for 9 plum cultivars (Prunus salicina) and 33 peach cultivars (Prunus persica), in a completely randomized design. The repeatability coefficient was estimated by methods of analysis of variance, principal components and structural analysis. The greates fruit weight was observed for Harry Pickstone and Pluma 7 plum cultivars and for Santa Aurea peach cultivar. The shortest lenght of cycle occurred in America, Irati and Methley plum cultivars and in Granada peach cultivar. The repeatability and determination coefficients were high for both traits in plum and in peach trees. There were no differences in the repeatability coefficient estimation among the methods used. One to three measurements of fruit weight and one and two measurements of length of cycle are necessary for obtaining the real genotypic values of plum and peach cultivars, respectively, with a determination coefficient of 90%.
Prunus persica; Prunus salicina; quantitative genetics; selection
