Prickly Pear Fruit Development and Quality in Relation to Gibberellic Acid Applications to Intact and Emasculated Flower Buds
The fruit of the prickly pear cactus (“Tuna blanca”, Opuntia amyclaea) has a sweet juicy pulp containing numerous hard-coated seeds, which limit the overall acceptability of the fruit. This study extended previous attempts to develop prickly pear fruits with reduced or smaller seed structures by applying gibberellic acid to floral buds. Solutions of gibberellic acid (GA3) were applied by spraying (100 and 500 ppm) or by injection (10 and 100 ppm) to intact or emasculated floral buds at three stages of development, and twice subsequently to the developing fruits. The GA treatments did not significantly affect fruit development when applied to intact floral buds, but reduced seed size when applied by injection. None of the treatments to emasculated buds resulted in fruit size or pulp development equal to that of the control fruits from intact floral buds. Spray application of 100 ppm GA to emasculated buds was the only treatment in which there was no hard seed coat development, but fruit size and percentage pulp were low as well. The other GA treatments were more effective in inducing pulp development but also resulted in the development of hardened seed coats (abortive seeds). These results further illustrate the dual role of the funiculus in the development of the pulp and seed coats in prickly pear fruits. The soluble solids contents of fruit pulp from intact and emasculated GA-treated buds were similar, but titratable acidity values were lower in the fruits from emasculated buds. GA treatments also tended to result in reduced peel firmness.