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 with some 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.

Exogenous Pre-harvest Application of Abscisic and Jasmonic Acids Improves Fruit Quality by Enhancing Sugar Synthesis and Reducing Acidity in Pomegranate (Punica granatum L. cv. Wonderful)

“…The addition of ABA to Seedless grapes, increased the berry weight, length, and diameter Lurie et al 2009). In agreement with our findings, Farag et al (2018) stated that the application of ABA individually on Wonderful pomegranates led to a significant increase in the fruit weight, fruit length and diameter, peel weight, and granule weight. The effects of ABA on the fruit weight depend on timing, dose, and kind of fruit (Balbontín et al 2018).…”

“…FW, fruit weight; FL, fruit length; FD, fruit diameter; AW, aril weight; PW, peel weight; TSS, total soluble solids; TA, total acidity; TSS/TA, total soluble solids/acid ratio; pH, pH; AI, anthocyanin index fruits as a result of the application of ABA (Mohamed et al 2019). However, ABA has not been elucidated to directly affect the fruit dimensions but rather to maintain cell turgor pressure, which increases the available water that could be used to raise the photosynthetic capacity and carbohydrate distribution in fruit (Farag et al 2018).…”

“…One of the major issues with pomegranate production is the lack of essential compounds, such as anthocyanin, which reduces the fruit's health-promoting qualities and affects the fruit's quality and marketability (Borochov-Neori et al 2013). Latterly, researchers have exhibited an increased interest in enhancing pomegranate fruit quality and quantity by utilizing some growth regulators such as jasmonic and abscisic acids (Farag et al 2018;García-Pastor et al 2020;Asghari et al 2020). Pomegranate producers in Upper Egypt suffer from a variety of production challenges, like fruit splitting, sunburn damage, and poor discoloration of arils and fruit skin (Attia 2017).…”

“…Discoloration of the fruit skin is a consumer purchase incentive, and non-invasive measures for its determination are underway (Czieczor et al 2018). Increasing the temperature of the skin and the inner fruit reduces the formation of anthocyanins and abscisic acid concentrations (Kataoka et al 1984;Farag et al 2018). Once the temperature rises, constitutive photomorphogenic 1 (COP1) is transported to the nucleus and destabilizes hypocotyl 5 (HY5), reducing anthocyanin biosynthesis (Liu et al 2021).…”

“…Abscisic acid (ABA) is a plant growth regulator (PGR) that plays an essential role in regulating environmental stress responses and plant growth and development, as well as fruit ripening (Chen et al 2020). In this interim, a few studies focused on ABA effects on pomegranate fruit quality attributes and coloration (Attia 2017;Farag et al 2018). The primary roles that ABA affects fruit maturity are by closing stomata and influencing the amount of carbohydrates in plants (Bound 2022).…”