The Effects of Gibberellic Acid and Emasculation Treatments on Seed and Fruit Production in the Prickly Pear (Opuntia ficus-indica (L.) Mill.) cv. “Gialla”

Prickly pear (Opuntia ficus-indica(L.) Mill. 1768) is cultivated in several dry and semi-dryareas of the world to produce fresh fruit, bioenergy, cosmetics, medicine, and forage. One of the mainproduction constraints is the presence of many seeds within the fruit, which can negatively influenceboth the fresh-fruit market price and industrial transformation processes. In this study, differentgibberellic acid (GA3) concentrations were tested for their ability to produce well-formed and seedlessfruits. Different application methods (injection and spraying) and concentrations of GA3(0, 100, 200,250, and 500 ppm) combined with floral-bud emasculation were applied to a commercial plantationin southern Italy to evaluate their effects on the weight, length, and diameter of the fruits, total seednumber, hard-coated viable seed number, and seed weight per fruit. The results indicated that theapplication of 500 ppm GA3sprayed on emasculated floral buds was the most effective method forreducing seed numbers of prickly pear fruits (−46.0%). The injection method resulted in a very lownumber of seeds (−50.7%) but produced unmarketable fruit. Observed trends suggest the need toinvestigate the impact of higher GA3concentrations and the applicability of a maximum threshold.Further studies are needed to increase our understanding of the physiological effects of the gibberellicacid pathway through productive tissue in terms of organoleptic and fruit quality