ASSESSING EFFECTS OF PREHARVEST ETHYLENE REGULATORS ON PHYSIOLOGICAL DISORDERS, QUALITY, PHENOLIC AND CARBOHYDRATE CONTENTS ON HONEYCRISP APPLES

Objective 1: Determine the effect of preharvest ethylene regulator treatments on reducing the incidence of physiological disorders, and fruit ripening patterns in 'Honeycrisp' apples.This first objective will function as a large screening study where we will assess the effect of three preharvest ethylene regulator treatments with different modes of action, and a control, on the incidence of physiological disorders and effects on ripening patterns of 'Honeycrisp' apples. The fruits will be harvested at two different maturity stages and then submitted to long-term storage (3ºC for 24 weeks + 20ºC for 1 week) with or without a conditioning treatment (10ºC for 1 week).Objective 2: Evaluate the effect of selected preharvest ethylene regulator treatments on fruit drop, quality, ethylene metabolism, accumulation of phenolic compounds and antioxidant activity in 'Honeycrisp' apples.Two select optimized treatments from objective 1(one from each maturity stage at harvest), along with a control (in each case), will be evaluated for their impact on preharvest fruit drop, quality, ethylene metabolism, phenolic metabolic-related pathways, and antioxidant activity in 'Honeycrisp' during preharvest, harvest, and cold storage (3ºC for 24 weeks + 20ºC for 1 week).Objective 3: Assess the impact of the selected preharvest ethylene regulator treatment on starch and sugar metabolism in 'Honeycrisp' apples.The most effective treatment selected from Objective 2, along with a control, will be used to assess its impact on starch and sugar metabolism-related pathways, at the gene, enzyme, and metabolites levels at harvest and throughout long-term cold storage (3ºC for 24 weeks + 20ºC for 1 week).Objective 4: Develop educational resources for growers and packers and extension-led outreach efforts to facilitate information dissemination and implementation.Effective extension and outreach efforts will be critical to deliver the knowledge and tools developed from this study to stakeholders that include apple growers, packers, Extension educators and regional specialists. We will demonstrate and train growers on the use of preharvest plant growth regulators and their effects on fruit preharvest through postharvest, on assessments of widely-used fruit harvest indices for apple optimum harvest maturity, as well as on pre- and postharvest management strategies to maintain optimal quality and prevent physiological disorders. Our extension efforts will also be targeted towards "underserved" Latino communities.