Isabel Ortega-Salazar, Carolina Torres
Aminoethoxyvinylglycine (AVG) is a plant growth regulator that has been widely used in apple production to reduce preharvest drop and delay fruit ripening by inhibiting ethylene biosynthesis. To test a new formulation (Retain ® OL) intended for organic production, various application rates and timings were used in different commercial apple blocks during three seasons (2019-2021). Fruit maturity and quality including skin color, flesh firmness, soluble solids, and background color, were measured preharvest and postharvest for up to 9 months in controlled atmosphere (CA) storage (‘Gala’: 0–1 °C and 2 MPa O 2 , 1 MPa CO 2 ; ‘Honeycrisp’: 3 °C and 2 MPa O 2 , 1 MPa CO 2, 85% relative humidity). Overall, organic AVG on ‘Gala’ and ‘Honeycrisp’ apples delayed fruit maturity at harvest and postharvest in a dose- and timing-dependent manner. In general, AVG-treated fruit maintained higher flesh firmness, averaging 8.6 N more than the control across all seasons, for up to 9 months plus 7 days at 20 °C (“shelf life”). Skin red color development decreased in some AVG treatments in ‘Gala’, and in all of them in ‘Honeycrisp’. In addition, the index of absorbance difference (I AD ) value was higher (greener background) in the treated fruit at harvest and postharvest, especially in ‘Honeycrisp’. Overall, Retain ® OL is a promising harvest management tool to optimize fruit quality at harvest and postharvest in organic apple systems.