EFFECT OF PREHARVEST SPRAYINGS OF BIOREGULATORS ON GROWTH AND RIPENING OF KEITT MANGO

Abstract

In Southern Sinaloa, Mexico, 21,204 ha of mango (Mangifera indica L.) of the Ataulfo, Tommy Atkins, Kent and Keitt cultivars are grown in the municipalities of El Rosario and Escuinapa, with a production in 2018 of 195,969 t. Keitt mango is of interest for being of late ripening (August-September). Empirical experiences indicate that if harvest period is extended and fruits increase their shelf-life, profitability may be improved. Therefore, the evaluation of development and maturation was proposed with the use of gibberellins (GA₃ 200 mg L^-1, Biogib®), cytokinins (Agromil Plus® 2.5 mL L^-1) as well as a fungicide (Manzate® 2.0 g L^-1) to combat anthracnose. Bioregulators, alone or mixed, were applied four times before harvest on May 3, June 6, July 2 and August 6, 2016, when fruits reached lengths of 8.1, 10.5, 11.6 and 12.4 cm, respectively. Fruits treated with Agromil Plus + GA₃ + Manzate increased 1.9 cm in diameter and 3.6 cm in length, compared to the control fruits. The accumulated fall of fruits was high in the controls (46 fruits/tree) and Agromil Plus (50 fruits/tree), but decreased with GA₃ to 28 fruits/tree, while the GA₃ + Agromil Plus + Manzate mixture decreased to 14.7 fruits/tree. This mixture was also the best treatment to maintain the shelf-life and reduce fruit anthracnose; this is shown by the increases in firmness of 95.3 newton, titratable acidity of 0.21 % citric acid, reductions in total soluble solids (TSS) of 3.7 ºBrix, TSS/acidity ratio by 27 and an anthracnose severity by 24 %, at 15 d of storage, compared to the control fruits. The use of GA₃ at preharvest may improve the quality and shelf-life of the Keitt mango when combined with cytokinins and fruits are protected against anthracnose with fungicide.