Efecto de la aminoetoxivinilglicina, el 3-5-6 TPA y el ANA en la caída y madurez precosecha de manzana Cv. Cripps Pink

Preharvest fruits drop is a problem present in Cripps Pink apple, a cultivar that increases its area annually in Uruguay. One management alternative to overcome this problem is the application of preharvest growth regulators. The present work evaluates the effect of aminoethoxyvinylglycine (AVG), naphthaleneacetic acid (ANA) and 3,5,6-trichloro-2-pyridyl-oxyacetic acid (3-5-6 TPA) on preharvest fruit drop and internal quality of apple. The treatments combined doses and times of application of the regulators as follows: AVG at 125 mg/L at 8 weeks preharvest (SP), AVG at 62 mg/L at 8 SP, AVG at 62 mg/L at 5 SP, 3-5-6 TPA at 20 mg/L at 8 SP, 3-5-6 TPA at 10 mg/L at 5 SP, and ANA at 17 mg/L at 5 SP. Fruits drop evaluation was carried out on floral centers with 1 fruit and with 2 fruits marked at the time of the first application, with weekly monitoring until harvest. Pulp pressure, soluble solids and starch degradation were evaluated at 2 and 1 SP. When comparing the control treatments, a greater fruit drop was observed in floral centers with 2 fruits compared to 1 fruit, 44% and 21%, respectively. The AVG at 125 mg/L and 3-5-6 TPA at 20 mg/L applied at 8 SP together with AVG at 62 mg/L and ANA at 17 mg/L applied at 5 SP showed effect on the reduction of fruits drop at 1 SP and at harvest in the floral centers with 2 fruits, also in the total drop (floral centers with 1 and with 2 fruits) at harvest time. No effect of the regulators was found in the 1 fruit flower centers. The effect of AVG doses on fruit retention depends on the time of application. The growth regulators did not differ from the control in the fruit maturity indicators when evaluating 2 and 1 SP. The treatments with AVG 125 mg/L-8 SP and ANA 17 mg/L-5 SP were the only ones to present a linear behavior in the fruit drop curve and did not show differences in drop when comparing the floral centers with 1 and 2 fruits at any time.