Estimation of Genetic Parameters for 12 Fruit and Vegetative Traits in the University of Florida Strawberry Breeding Population

The University of Florida strawberry (Fragaria xananassa) breeding population has been continuously improved by recurrent selection since 1968. However, there is a lack of information on genetic parameters that may inform breeding decisions. Parameters were estimated in this population using 19 full-sib families from a 5 x 4 factorial mating design plus six additional biparental crosses and 14 control genotypes including some of the parents. During the 2010-11 season, clonal replicates of the seedling and parental genotypes were distributed within and among two field locations in west central Florida. Twelve commercially important traits were measured including fruit chemical traits (soluble solids content and titratable acidity), other fruit and yield traits (early and total marketable yields, proportion of total cull fruit, proportion of misshapen fruit, proportion water-damaged fruit, and shape score), and vegetative traits (plant height and total runners). Heritabilities, genotype by environment interaction, and multiple correlations (phenotypic, genotypic, and genetic) were estimated using general mixed model analyses. Narrow-sense heritabilities varied from low to moderate (h(2) = 0.13 +/- 0.07 to 0.32 +/- 0.09) except for shape score (h(2) = 0.06 +/- 0.04) and total average weight (h(2) = 0.52 +/- 0.07). Broad-sense heritabilities were larger (H-2 = 0.18 +/- 0.03 to 0.53 +/- 0.04), and for more than half of the traits, over 50% of the total genetic variation was non-additive. Large genetic and genotypic correlations were found for some traits, most notably between soluble solids content and early marketable yield (-0.68 +/- 0.22). Genetic gains for this pair of traits based on a Monte Carlo simulation illustrated the tradeoff between these two traits, showing that a 27% increase in early yield could be obtained through selection but at the expense of an 8% decrease in soluble solids. However, moderate gains can be made in both traits using the appropriate index coefficients.