The objective of this work was to study the effect of gibberellic acid on "Valência" orange fruits, when applied at various concentrations, under different solution pH. The treatments consisted of 5 concentrations of gibberellic acid (0; 5; 10; 15; and 20 ppm) and 3 pHs (3; 4.5; and 6). The aplication was made in May, when fruits were at green-yellow stage, and samples were collected every 30 days until November. The variables studied were coloration and thickness of the peel, total soluble solids (TSS), pH of juice, percent of juice, total acid (TA), ratio TSS/TA and technological index. The results obtained did not allow to conclude that gibberellic acid had any influence on the characteristics of the juice. The thickness of the peel was not affected by gibberellic acid. However, gibberellic acid caused a retaintion of the green color of the peel with increasing concentration, causing the fruits to remain greener. This was observed for all solution pHs. At pH 3, the fruits were greener than under the other pHs, and at the normal pH (4.5) The green coloration in the fruits persisted for a louger time than at pH=6, suggesting that acid pHs increase the uptake of gibberelic acid by the plants. It was also observed that gibberellic acid delayed the regreening of the fruits, what happens when the temperature becomes higher.
Citrus sinensis; Valência orange; gibberellic acid; maturation
