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

Lorenzo Marini,Enrico Palchetti,Alberto Masoni,Lorenzo Brilli,Alessandro Calamai,Pietro Fino,Chiara Grassi

doi:10.3390/horticulturae6030046

Lorenzo Marini, Enrico Palchetti + Show 5 more

Open Access

https://doi.org/10.3390/horticulturae6030046

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Abstract

Prickly pear (Opuntia ficus-indica (L.) Mill. 1768) is cultivated in several dry and semi-dry areas of the world to produce fresh fruit, bioenergy, cosmetics, medicine, and forage. One of the main production constraints is the presence of many seeds within the fruit, which can negatively influence both the fresh-fruit market price and industrial transformation processes. In this study, different gibberellic acid (GA3) concentrations were tested for their ability to produce well-formed and seedless fruits. 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 plantation in southern Italy to evaluate their effects on the weight, length, and diameter of the fruits, total seed number, hard-coated viable seed number, and seed weight per fruit. The results indicated that the application of 500 ppm GA3 sprayed on emasculated floral buds was the most effective method for reducing seed numbers of prickly pear fruits (−46.0%). The injection method resulted in a very low number of seeds (−50.7%) but produced unmarketable fruit. Observed trends suggest the need to investigate the impact of higher GA3 concentrations and the applicability of a maximum threshold. Further studies are needed to increase our understanding of the physiological effects of the gibberellic acid pathway through productive tissue in terms of organoleptic and fruit quality.

Highlights

Pear (Opuntia ficus-indica (L.) Mill.) is the most cultivated plant species in the Cactaceae family due to edible fruit production [1]
Pear cultivation is important in several dry and semi-dry areas of the world owing to its diverse uses
The results of GA3 application on fruits indicated that 500 ppm of GA3 sprayed on emasculated floral buds was the most effective technique for reducing the number of seeds within prickly pear fruits

Summary

Introduction

Pear (Opuntia ficus-indica (L.) Mill.) is the most cultivated plant species in the Cactaceae family due to edible fruit production [1]. It is a bushy-shaped, xerophytic, and crassulacean acid metabolism (CAM) plant originating from dry areas of Mexico [2]. The annual global production of prickly pear is approximately 500,000 tons, and Italy supplies 12% of the total market, preceded by Mexico and followed by Israel [3,4]. Despite numerous species of the Opuntia genus being mainly cultivated to produce fresh fruit, this cultivation can play a key role in other contexts, such as environmental defense, forage and bioenergy production, the medicine and cosmetics sectors, and human health [1,6,7,8]. In some tropical agroforestry systems, Opuntia elatior (Mill.)

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