Exogenous Application of Melatonin and Methyl Jasmonate as a Pre-Harvest Treatment Enhances Growth of Barhi Date Palm Trees, Prolongs Storability, and Maintains Quality of Their Fruits under Storage Conditions

Abstract

Fresh date palm fruits (cv. Barhi) have received much attention due to their sweet taste and popularity in marketing. There is a critical need to prolong their storability, as well as maintain their quality during the postharvest and marketing periods. In this study, the effects of spraying date palm trees with melatonin (Mt) and/or methyl jasmonate (Mj) at 10, 20, and 50 ppm, on their growth and yield were investigated. In addition, impacts on quality and storability of the fruits were also studied. In general, application of Mt was mostly more effective than that of Mj, even at 50 ppm, with regard to all evaluated parameters. However, the dual treatment at 50 ppm recorded the highest relative chlorophyll and nutrient content in date palm leaves, as well as the yield and its components. Regarding the date palm fruits stored at 4 °C for 28 days, this dual treatment recorded the lowest weight loss and fruit decay values (0.14 and 2%, respectively), the highest firmness (6 g·cm−2), total soluble solids content (36 °Brix), total sugar content (32.5 g/100 g fresh weight), and the lowest total acidity (0.16 g citric acid/100 mL juice). Moreover, the highest total phenolic content and activity of peroxidase and polyphenol oxidase enzymes in the stored fruits were also recorded for the dual treatment. In contrast to the untreated fruits, scanning electron microscopy observations showed that the sprayed fruits had a very good microstructure, showing intact and thick exocarp tissue with a dense layer of epicuticular wax. The mesocarp tissue showed a normal and clear cellular framework with well organized and arranged cells, after 28 days storage at 4 °C. Based on these results, we can conclude that application of the dual treatment (Mt + Mj) at 50 ppm is a promising way to prolong the storability of date palm fruits and maintain their quality during storage periods.

Yellow Pitahaya (Selenicereus megalanthus Haw.) Growth and Ripening as Affected by Preharvest Elicitors (Salicylic Acid, Methyl Salicylate, Methyl Jasmonate, and Oxalic Acid): Enhancement of Yield, and Quality at Harvest

“…In tomato, yield was enhanced after MeJa and SA preharvest treatments, the performance being higher in MeJa-treated plants, which has been attributed to the effect of MeJa on alleviating abiotic stress and is associated with an improvement of the net photosynthesis rate and productivity [34]. In pomegranates, jasmonic acid (JA) enhanced the size and quality traits of 'Wonderful' pomegranate [35], since JA plays essential roles in fruit and growth development [19]. In fact, MeJa at 0.5 mM not only enhanced the bioactive compounds and quality, but also increased the productivity and yield.…”

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

“…Our findings correspond with those obtained on date palms, pomegranates, apricots, and cherries [ 35 , 39 , 40 , 41 ]. Furthermore, the findings suggest that preharvest MT treatment could reduce the respiratory rate of kiwifruit during early storage and retain its firmness at the end of storage [ 40 , 45 , 46 , 47 ]. These findings show that MT slows the softening and senescence of kiwifruit by lowering the respiration rate, hence reducing the water content of kiwifruit during storage.…”

Evaluation of Different Insecticides Against Lesser Date Moth, Batrachedra amydraula Meyrick, 1916 (Lepidoptera: Batrachedridae) under Field Conditions

“…The date palm dry and semi-dry fruits contain both macro and micronutrients which are playing a pivotal role in the functions of the human body and are rich in vitamins, nutrients, minerals, dietary fibers proteins (Rambabu et al, 2020), and a significant amount of carotenoids, phytosterols and Polyphenols (Mia et al, 2020). Due to their popularity in marketing and sweet taste date fruits have received much attention (Fekry et al, 2022), and are regarded as the ideal healthy food for humans (Al-Shahib and Marshall, 2003). The economy of rural areas and the use of edible plants as a food source play important roles in health improvement (Khan et al, 2022).…”