Efficiency of CaCl2 spray at different fruit development stages on the fruit mineral nutrient accumulation in cv. Hayward kiwifruit

Despite the importance of calcium in many fruit species and the effects of calcium application, there is little or no reliable information on the effect of CaCl2 spray at different fruit development stages on the fruit mineral nutrient content during the growing season and at harvest. Therefore, this study has been conducted to evaluate the effect of calcium chloride (CaCl2, 15 g L-1) spray at different fruit development stages on the accumulation Ca and other macronutrients in cv. Hayward kiwifruit grown at two locations. In order to find the absorbality of Ca at different spraying times, fruits were harvested 7 days after a Ca treatment. Additionally, the mineral composition of kwifruit was determined at the stage of harvest ripeness. The results showed that the absorbality of Ca by kiwifruit from Ca spray decreased significantly with the progressing fruit development. The highest fruit Ca content was found when the fruit plants were sprayed at 35+80 DAFB and 35+80+120 DAFB, irrespectively of the location of an orchard. At a later Ca spraying application, the N content in kiwifruit significantly decreased, but the K and Mg content slightly increased. In contrast, the K/Ca, N/Ca, Mg/Ca and (K+Mg)/Ca ratios of CaCl2 sprayed fruits was lower than in the control and the ratio values were more balanced in the Ca treated fruit than in the control. Overall, three CaCl2 (15 g L-1) sprays could effectively improve the fruit quality by balancing the Ca ratio to other macronutrients. Therefore, Ca spray treatments could be a recommended treatment in growing cv. Hayward kiwifruit.