Prolonging shelf life of flame seedless table grapes with pre-harvest calcium and magnesium treatment

¹ Pomology Department, Faculty of Agriculture, Cairo University, Giza, Egypt

^* Corresponding author: saharwahab@uokufa.edu.iq

Abstract

Nutritional balance methods serve as effective tools for predicting the nutritional status of grapevines and mitigating issues related to nutrient excess or deficiency, thereby influencing yield, fruit quality, and market longevity. This study investigates the effects of pre-harvest applications of calcium (Ca) and magnesium (Mg) at varying concentrations, individually and in combination, on grape quality. Pre-harvest foliar applications were conducted six times across three key phenological stages: pre-bloom, post-bloom, and fruit set. Treated clusters were stored in refrigerated conditions (10°C, 90–95% relative humidity) for 12 days, during which fruit quality was evaluated at harvest and throughout the marketing period. The results demonstrated that prolonged market storage increased decay, weight loss, Soluble solids content (S.S.C.), total sugar content, shattering, berry adherence, and respiration rate, while firmness, total acidity, vitamin C content, and total phenols decreased. All treatments enhanced cluster weight and yield at harvest. The most effective treatment for maintaining cluster quality under market conditions was the combined foliar application of magnesium oxide (MgO, 0.056%) and calcium chloride (CaCL·>, 0.016%). This treatment significantly reduced physiological weight loss, berry shattering, and decay percentage, thereby preserving the marketability of ‘Flame Seedless’ grapes.