Effects of preharvest abscission agent application on postharvest quality of destemmed Autumn King and Sheegene-12 table grape berries

Table grapes have high production costs partly due to laborious picking and packing practices. Mechanized harvest is not yet feasible for whole table grape clusters, but it might be suitable for “fresh cut” (destemmed) table grapes if mechanical damage could be minimized. Preharvest application of methyl jasmonate (MeJA) and 1-aminocyclopropane-1-caboxylic acid (ACC) activate the abscission zone of some grape varieties, improving harvestability and reducing harvest wounds, but effects on postharvest quality of destemmed berries are unknown. Sheegene-12 and Autumn King table grapes treated with 3 mM MeJA and 500 to 750 ppm ACC were destemmed and berry condition evaluated at harvest, and after two and four weeks of postharvest storage. Treatments improved harvestability and reduced destemming wounds of both varieties and generally improved the quality of Sheegene-12 berries at harvest, and after postharvest storage. However, treated Autumn King berries became darker, and more yellow-colored in storage, which is undesirable.