Wednesday, August 10, 2016
Georgia Ballroom (Sheraton Hotel Atlanta)
The purpose of this study was to investigate the influence of fruit position, harvest sequence and light environment on the occurrence of soft scald during storage of Malus domestica 'Honeycrisp' apples. Three fruit positions within the tree were investigated: top (2.1 meters above ground), middle (1.5 meters) and bottom (1.2 meters); fruit was harvested three times in weekly intervals under netting (Extenday™, 20% reduction in radiation) and control ( no netting). Samples were collected from an orchard in Gleed (Yakima County, Washington, USA) in 2015. After harvest, fruit was analyzed using standard maturity indicators (soluble solids content, titratable acidity, firmness and starch index). The remaining fruit was stored in a commercial cold room for three months at 0.5 °C and semi-weekly measurements of the DA-index and soft scald occurrence (absent/present) were performed. We utilized the DA meter to determine its utility on non-destructively tracking fruit in forced chilling conditions to determine its capacity to detect chilling stress before visual symptoms appear on the fruit surface. The first soft scald symptoms were observed two weeks after harvest. At the conclusion of the study, fruit with advanced maturity at harvest (third pick) showed higher incidence of soft scald (up to 79 %) than samples from the first (0 %) and second (4 - 8 %) pick. Furthermore, fruit position within the tree influenced the onset and the severity of soft scald symptoms. For example, fruit from the third pick, showed a higher soft scald occurrence (79 %) in fruit samples from the bottom than the fruit from the middle (54 - 58 %) and top (33 %) part of the canopy. There was no significant difference between the netting and control treatment. The DA-index did not correlate with the occurrence of chilling injury in this and other studies. The possibility to improve postharvest performance of 'Honeycrisp' apples based on orchard criteria will be discussed.