Dynamic Changes in Sugar Concentrations in the Fruit Peel of ‘Cara Cara’ Navel Orange (Citrus sinensis L. Osbeck) After Exogenous Application of ABA and GA3

The dynamics of glucose, fructose, and sucrose concentrations were determined after exogenous abscisic acid (ABA) and gibberellic acid (GA3) treatments during the early period of fruit growth and immediately before color break in the fruit peel of ‘Cara cara’ navel orange (Citrus sinensis L. Osbeck). ABA treatments at 10 mg L-1 significantly increased the glucose, fructose, sugar, and total sugar concentrations, whereas ABA treatments at 50 and 100 mg L-1 significantly decreased the glucose, fructose, sucrose, and total sugar concentrations during the early part of fruit maturation. As the fruits matured, the level of all sugars, except sucrose, was highest in fruits treated with 100 mg L-1 ABA. GA3 treatment significantly decreased the glucose, fructose, sucrose, and total sugar concentrations at fruit maturation. Sugar concentration in the fruit peel of navel orange could be regulated by the type and concentration of plant hormones and the time of their application in the course of fruit development.