EXTENDING POSTHARVEST QUALITY ATTRIBUTES OF GRAPES (V. vinifera L. cv. ‘THOMPSON SEEDLESS’) BY PREHARVEST CALCIUM PULVERIZATIONS

Demand for fresh grape is increasing globally in accordance with the improvement in living standard since the grape berry contains large amounts of phytochemicals including anthocyanins, phenolics, flavonoids and resveratrol, which have been suggested to be responsible for human health benefits. However, table grapes easily undergo deterioration due to their soft texture and the high water content, which make it difficult to preserve without treatment. This study was thus conducted to evaluate the effect of preharvest calcium sprays on maintenance of postharvest quality of grapes (V. vinifera L. cv. ‘Thompson Seedless’). Three preharvest calcium sprays were applied to leaves and developing green berries with or without leaf removal pruning (a traditional practice performed in commercial vineyards worldwide) during berry development stages. After harvest, grapes were cold stored (1°C, 90% R.H.) up to 3 months. Preharvest micronized calcium sprays, with or without leaf removal pruning, markedly extended the postharvest quality of grapes by delaying weight loss, reducing decay, maintaining rachis chlorophyll concentrations and preserving visual quality during the prolonged cold storage. Besides, in calcite-treated grapes, lower titratable acidity decrease courses with a subsequent lower maturity index during prolonged storage indicate that calcite sprays restricted postharvest physiological senescence of grapes. Overall findings indicated that preharvest calcite sprays may be an environmental-friendly, healthy and sustainable viticulture practice for extending postharvest quality of grapes.