2017 ASHS Annual Conference

The diversity and relationships of fruit quality traits peach and nectarine (Prunus persica L.) in the National Prunus collection were studied using comprehensive phenotyping methods. The collection was re-propagated in 2013 and planted in 2014 providing a unique opportunity to evaluate an even-aged, bearing population with large genetic diversity. This sample population consists of 360 accessions from diverse lineages (breeders’ lines, Western cultivars, Asian cultivars, and wild germplasm). Comprehensive phenotyping methods, including electronic data capture and standard protocols were used. Traits evaluated included physical parameters (fruit weight, size, flesh color, percentage red overlay, percentage blush, firmness, type, shape, endocarp adhesion, amount of fuzz, and flesh texture), and chemical parameters [soluble solids concentration (°Brix), titratable acidity (TA), Brix/acid ratio (°Brix/TA), and pH]. Phenological traits were also recorded, including: full bloom date, leaf-out date, fruit maturity date, and fruit development period (days from full bloom date to maturity date). Unique combinations of flesh color, percentage red overlay, percentage blush, and fruit type were observed. Fruits were harvested from 2 replicates for each genotype when mature, and analyzed at tree ripe stage for all physical and chemical traits. Traits were measured on 12-24 fruit per replicate for each genotype with mean values from 5 fruit for each trait used for analysis. Fruit maturity dates ranged from May to October, with fruit development periods from as short as 67 days to as long as 230 days with a mean of 134 days. Soluble solids ranged from as low as 6.2 °Brix to as high as 20.1 °Brix with a mean of 13.4 °Brix. Titratable acidity ranged from 0.14% to 2.1% with a mean of 0.64%. The Brix/acid ratio (°Brix/TA) ranged from 6.5 to 132.8 with a mean of 26.8. Numerous correlations among fruit quality and phenological traits across diverse lineages have been observed. Phenotypic diversity of the NCGR Prunus collection and the invaluable resource it presents to peach breeding programs will be discussed.