Heritability and Phenotypic Correlations in Peach [Prunus persica (L.) Batsch]

Fifteen peach [Prunus persica (L.) Batsch] horticultural and fruit quality traits were evaluated for two years at Fowler, CA and one year at College Station, TX to estimate heritability and phenotypic correlations. Seedlings from nine F1 families along with parents used in crosses, were budded onto ‘Nemaguard’ rootstocks for evaluation. An all random effects model (REML) was used to estimate variance components and a multivariate model was used to estimate phenotypic correlations between traits. High and moderate to high heritability was estimated for bloom date (h^(2) = 0.62) and fruit ground color (h^(2) = 0.50), while ripe date, fruit development period (FDP), fruit weight, red in the flesh, firmness, soluble solids, titratable acidity (TA), and pit weight showed low narrow sense heritability (h^(2) = 0.05-0.24). These traits with low narrow sense heritability had moderate to high broad sense (H^(2)) heritability, indicating an important non-additive genetic component. Intermediate values of heritability (h^(2) = 0.38 – 0.46) were found for pubescence, blush, fruit diameter, fruit tip, and fruit shape. Two major genes had effects on additive heritability. Nectarine had a direct effect on heritability of fruit pubescence, while pantao shape and nectarine had pleiotropic effects on fruit diameter, resulting in higher estimates for both of these traits. Several traits (fruit red blush, fruit weight, fruit diameter, fruit tip, fruit shape, and fruit ground color, red in the flesh, fruit firmness, and soluble solids) were strongly affected by genotype by environmental interaction. Most traits exhibited substantial variability, which should allow for genetic improvement. Ripening date was strongly correlated (r = 0.94) with FDP, while bloom date was negatively correlated with FDP (r = -0.45) and fruit tip (r = -0.40). Ripening date and FDP were moderately correlated with fruit weight (r = 0.54, r = 0.50) and fruit diameter (r = 0.46, r = 0.45). Both measures of fruit size were strongly correlated (r = 0.77). Soluble solids was somewhat weakly correlated with ripening date and FDP (r = 0.32, r = 0.33). Pit weight was moderately correlated with FDP, fruit weight, and fruit diameter (r = 0.33, r = 0.51, r = 0.31, respectively)