2018 ASHS Annual Conference

This study examined the relationship between the length of the fruit development period and fruit quality traits in a phenotypic analysis of the Prunus persica collection of the USDA -ARS National Clonal Germplasm Repository. Previous studies have examined the influence of fruit maturity date on soluble solids concentration but had limited sample populations and neglected to account for the phenological variability and management effects on fruit quality traits. This study addressed these key issues and analyzed the relationship between fruit development period and fruit soluble solids concentrations, titratable acidity and soluble solids/titratable acidity ratios. The sample population consisted of 360 genotypes from diverse lineages (breeders' lines, Western cultivars, Asian cultivars, and wild collections) with large phenotypic variation. A growing degree hour model was used to analyze data from an on-site weather station to control for phenological variation due to temperature changes. Orchard management included standardized commercial practices including tree pruning, fruit thinning and consistent irrigation and nutrient applications. Fruit were harvested from 2 replicate trees for each genotype when mature, and analyzed at tree ripe stage. Composites of juice from 5 fruit were processed from each replicate and soluble solids concentrations and titratable acidity were calculated using standard postharvest procedures. The fruit development periods were compared against soluble solids concentration, titratable acidity, and soluble solids concentration/titratable acidity ratios at maturity, with mean values used for each genotype. Further analysis was completed by grouping these genotypes by parameters such as origin, acid type, flesh color, and endocarp adhesion. Statistical analysis was completed using R. Overall, there was a linear trend of increased soluble solids concentration with longer fruit development periods, with a significant source of the variation attributable to the interaction of fruit development period and soluble solids concentration. This indicated that fruit development period was a limiting factor for soluble solids concentration in P. persica and that there may be challenges in breeding genotypes with short fruit development periods and high soluble solids concentrations. Titratable acidity and soluble solids concentration/titratable acidity ratio showed no linear trends. Numerous other correlations were observable among groups including; wild collected genotypes, sub-acid types and other groups. These group interactions may provide insight as to the effect of fruit development period on important fruit quality traits.