HERITABILITY, GENETIC AND PHENOTYPIC CORRELATIONS, AND PREDICTED SELECTION RESPONSE OF QUANTITATIVE TRAITS IN PEACH - I - AN ANALYSIS OF SEVERAL REPRODUCTIVE TRAITS

Seedlings of 108 families from crosses among 42 peach [Prunus persica (L,) Batsch] cultivars and selections were evaluated for six plant cha racteristics in 1993, 1994, and 1995. The data were analyzed by using a mixed linear model, with years treated as fixed and additive genotyp es as random factors. Best linear unbiased prediction (BLUP) was used to estimate fixed effects. Restricted maximum likelihood (REML) was us ed to estimate variance components, and a multiple trait model was use d to estimate genetic and phenotypic covariances among traits. The nar row-sense heritability estimates were 0.41, 0.29, 0.48, 0.47, 0.43, an d 0.23 for flower density, flowers per node, node density, fruit densi ty, fruit set, and blind node propensity, respectively. Most genetic c orrelations among pairs of traits were greater than or equal to 0.30 a nd were, in general, much higher than the corresponding phenotypic cor relations. Flower density and flowers per node (r(a) = 0.95), fruit de nsity and fruit set (r(a) = 0.84) and newer density and fruit density (r(a) = 0.71) were the combinations of traits that had the highest gen etic correlation estimates. Direct selection practiced solely for flow er density (either direction) is expected to have a greater effect on fruit density than direct selection for fruit density.