Objective Effects of different calcium fertilizers and application methods on the fruit quality of Kyoho grape were studied to provide guidelines for the production and cultivation.
Method Four-year-old Kyoho grape vines were cultivated in a rain shelter facility to observe the results under treatments of varied calcium fertilizers and applications. Two different calcium fertilizers, 1 500 x sugar alcohol calcium and 800 x calcium nitrate, were used to either spray on the leaves and/or fruit ears or combine the spraying with rhizosphere irrigation. Grape peel color, calcium contents in different parts, and soluble solid, total sugar, and total acid contents, as well as firmness of the fruits were monitored.
Result The fertilizing method affected both the peel color change and pulp quality as well as the calcium content in different parts of the grapes. When the leaves and fruit ears were sprayed and accompanied by rhizosphere irrigation with the sugar alcohol calcium fertilizer, the pericarp color was intensified. The contents of total phenols, anthocyanins, covalently bound pectin, and ion-bound pectin of the grapes also increased to become significantly higher than those of control. The calcium contents in peel and pulp were 1.36 and 1.73 times of control, respectively; the flesh firmness 19.28% higher than that of control; and the soluble solid mass fraction 5.71% higher than that of control.
Conclusion The calcium fertilizations improved both internal and external quality of Kyoho grapes. By combining the foliar-and-ear spraying with rhizosphere irrigation using the 1,500x sugar alcohol calcium fertilizer, significant improvements on the fresh fruit quality could be realized.
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