Effects of Melatonin Treatment on Sweet Cherry Tree Yield and Fruit Quality

Abstract

The effects of preharvest melatonin treatment, applied as foliar spray at 0.1, 0.3 and 0.5 mM concentration at three key points of fruit development (pit hardening, initial colour changes and 3 days before harvesting), on crop yield and fruit quality properties at harvest was evaluated in three sweet cherry cultivars, ‘Prime Giant’, ‘Lapins’ and ‘Sweet Heart’, and two years, 2019 and 2020. The results showed that melatonin treatment had no effect on crop yield, except for the ‘Lapins’ cultivar, in which increases were found. However, decayed and cracked fruit percentage was decreased in all cultivars in 2020 when adverse weather conditions occurred and commercial crop yield was increased, especially for 0.3 mM dose. Fruit quality traits at harvest, such as fruit weight, colour, firmness, total soluble solids and titratable acidity, were enhanced by melatonin treatments in all sweet cherry cultivars and in both years. Moreover, bioactive compounds, such as total phenolics and total and individual anthocyanins, were also found at higher levels in fruit from melatonin-treated trees with respect to controls. Thus, taking into account all these effects, 0.3 mM melatonin foliar spray, at three key points of fruit developmental stages, could be a useful tool to improve crop yield and quality traits of sweet cherries, especially their content on bioactive compounds with antioxidant properties and health beneficial effects.

Melatonin Pre-harvest Treatments Leads to Maintenance of Sweet Cherry Quality During Storage by Increasing Antioxidant Systems

“…These ROS are generated in normal metabolism of plant cells and scavenged by antioxidant compounds (such as phenolics, tocopherols, carotenoids, and ascorbic acid) and by antioxidant enzymes, mainly superoxide dismutase (SOD), POD, CAT, and APX contributing to repair cell oxidative damage ( Hodges et al, 2004 ; Kumar et al, 2014 ). Antioxidant enzymes were measured in fruit from control and 0.3 mM treated trees, since, in general, similar effects on maintaining cherry quality properties were observed for 0.3 and 0.5 mM concentrations, as well as on increasing crop yield ( Carrión-Antolí et al, 2022 ). The results of the present study show higher activities of these antioxidant enzymes in melatonin treated trees than in controls during the whole storage period in both cultivars ( Figures 5A–F ).…”

“…In the last decade, special attention has been paid to the content on bioactive compounds with antioxidant activity, such as anthocyanins and other phenolic compounds, in sweet cherry due to their positive impact on human health, by reducing the risk of suffering from several degenerative diseases ( Correia et al, 2017 ; Gonçalves et al, 2018 , 2019 ; Antognoni et al, 2020 ; Faienza et al, 2020 ; Luo et al, 2021 ). In this fruit species, the red colour intensity is due to their content of anthocyanins and their profile, the major anthocyanin being cyanidin 3- O -rutinoside comprising around 90% of total anthocyanins, and 70% of total phenolic compounds, in most of the studied cultivars, including ‘Prime Giant’ and ‘Sweet Heart’ ( Usenik et al, 2008 ; Serrano et al, 2009 ; Martínez-Esplá et al, 2014 ; Antognoni et al, 2020 ; Gonçalves et al, 2021 ; Carrión-Antolí et al, 2022 ). Total phenolic concentration showed an upward trend from day 0 until the end of storage in fruit from control and treated trees for both cultivars ( Figures 4A,B ), while total anthocyanins, generally, increased during the first weeks of storage and decreased thereafter ( Figures 4C,D ).…”

“…For each cultivar, three blocks of three trees were selected at random for 0 (control), 0.1, 0.3, and 0.5 mM melatonin treatments. Treatments were applied with a manual sprayer machine (3 L per tree) by using freshly prepared melatonin solutions (containing 1 mL L –1 Tween as surfactant) at three key points of fruit development (pit hardening, starting of colour changes and 3 days before harvest), according to previous reports ( Giménez et al, 2017 ; Carrión-Antolí et al, 2022 ). Sweet cherries were harvested according to commercial practices, when reached their commercial ripening stage, based on the soluble solid content and skin colour of each cultivar.…”

“…On the contrary, foliar spray treatment with 0.5 mM melatonin 2 and 1 weeks prior to harvest accelerated fruit ripening of sweet cherry ‘Ferrovia’ ( Michailidis et al, 2021 ). In our previous paper, pre-harvest foliar spray with 0.1, 0.3, and 0.5 mM melatonin led to fruit with enhanced quality traits at harvest, such as fruit weight, colour, firmness, total soluble solid content and titratable acidity ( Carrión-Antolí et al, 2022 ). However, as far as we know, there is not available literature regarding the effect of pre-harvest melatonin treatment on the maintenance of sweet cherry fruit quality properties during storage.…”

Evaluation of Preharvest Melatonin on Soft Rot and Quality of Kiwifruit Based on Principal Component Analysis

“…The kiwifruit morphology plays a crucial role in luring customers and is one of the critical markers of postharvest grading and selection [ 38 ]. According to earlier research, preharvest exogenous melatonin treatment boosted fruit yields and weights in grapes, pomegranates, and sweet cherries [ 39 , 40 , 41 ]. In this study, preharvest melatonin spraying significantly maintained the weight and volume of a single kiwifruit fruit.…”