Heritability and Phenotypic Correlations among Bloom, Flower Density, and Fruit Set

The peach breeding program at Texas A&M University has been working on the development of peach and nectarine cultivars adapted to the low and medium chill zones. As the major emphasis of the program is to introgress the superior horticultural traits from poorly adapted high chill germplasm into the marginal quality but well adapted low and medium chill germplasm, adaptation traits of bloom time, flower density and fruit set are essential to ensure consistent productivity. In conjunction with the RosBREED SCRI program, nine F1 peach populations were characterized for bloom date over two years in both California and Texas. In addition to this, these populations growing in College Station were assessed for flower density (2 years) and fruit density (1 year). An all random effects model (REML) was used to estimate variance components and a multivariate model was used to estimate phenotypic correlations between traits. All three traits showed high broad sense heritability as has been previously reported with other populations. Narrow sense heritability estimates for bloom date and fruit density were moderate to high whereas the narrow sense heritability estimate for flower density was low indicating a large non additive genetic variance. Correlation analysis indicates that there is a good correlation between flower and fruit density. The next step in this study is to subject this data to a FlexQTL analysis to identify trait-marker associations.