Effects of calcium spraying to the leaves and fruits on postharvest physiological characteristics of papaya fruits

In order to evaluate the effect of foliar application of calcium chloride (0, 0.5, 1, 1.5 and 2%) to the aerial parts of the plant (leaves, fruits and leaves plus fruits) on postharvest quality of papaya fruit, a trial was conducted in the orchards of Universiti Putra Malaysia during the year 2012. The results showed that the highest calcium content was observed in the fruits where the spray had been applied to the fruits or fruits plus leaves, while the lowest calcium content was recorded when the spray had been applied to the leaves. In addition, the magnesium content in the peel and pulp of fruits where the spray had been applied to the fruits or fruits plus leaves, was the lowest while the highest was observed when the spray had been applied to the leaves. The respiration rate and ethylene production decreased in fruits where the spray had been used on the fruits or fruits plus leaves. However, the soluble solids content was the lowest in the fruits where the spray had been applied to the fruits plus leaves, followed by the spraying of fruits and leaves alone. The inverse results were recorded for titratable acidity. In addition, results showed that when calcium was applied to the fruits and leaves overall quality was the best followed by spraying of fruits and leaves alone. Moreover, the calcium content in the peel and pulp, titratable acidity and overall quality increased when the application of the calcium chloride concentration in fruits and fruits plus leaves increased. Moreover, the calcium content in the peel and pulp, titratable acidity and overall quality increased when the calcium chloride concentration applied to the fruits and fruits plus leaves increased. While the increased calcium concentrations had no effect on the calcium content in the peel and pulp when applied to the leaves, the titratable acidity increased with increasing calcium chloride concentrations. The results of this study showed that calcium could not transfer from leaf to fruit and vice versa in papaya.