REDUCING CRACKING AND ENHANCING COLORATION AND QUALITY OF WONDERFUL POMEGRANATES CULTIVAR BY SAFE TREATMENTS

Abstract

Pomegranates fruit cracking and poor coloration of peel and aril are the main problems facing the expansion of its cultivation especially under arid condition in the desert. This study was conducted during the two successive seasons 2014 and 2015 on Wonderful pomegranates (Punica granatum L.). The trees were grown under drip irrigation system in a private orchard at Nubaria region, Beheira Governorate, Egypt. The trees were treated twice at weekly interval by using a hand sprayer to the run off point at the marble size withsome mineral nutrients to reduce fruit cracking. The treatments included: water spray (as the control), calcium borate at 100 ppm, calcium borate at 200 ppm, zinc chelated with EDTA at 100 ppm, zinc chelated with EDTA at 200 ppm and finally calcium nitrate at 1% (W/V). Moreover, to enhance coloration of pomegranates peel and aril, at maturity the trees were treated with the control (water spray), ProTone (ABA 1%) at 100 ppm, ProTone at 100 ppm plus glycerol at 1% (V/V), ProTone at 100 ppm plus potassium sulphate at 1% (W/V), ProTone at 100 ppm plus potassium sulphate at 1% and glycerol at 1% (V/V), glycerol at 1% (V/V) and finally potassium sulphate at 1% (W/V). The non-ionic surfactant Top film at 0.05% (V/V) was added to all treatments. The results proved that calcium borate at 200 ppm treatment was more effective on reducing cracking and sun scald of pomegranate fruits. In addition, the results revealed that the formulation containing ProTone plus potassium sulphate and glycerol had a consistent effect on increasing anthocyanin content in the peel, when compared with the control or with ProTone alone. Moreover, anthocyanin content of the arils was significantly increased by application ProTone along with glycerol or ProTone plus potassium sulphate and glycerol in both seasons. Meanwhile, electrolyte leakage of the aril was similar for most applications. There was also a significant increase in total sugars by various ProTone-containing formulations relative to the control in the juice. Thus, this study recommended applying ProTone in a formulation containing potassium sulphate and glycerol in order to enhance coloration and quality of Wonderful pomegranates in a consistent manner under field conditions.