Late-season foliar application of mineral compounds effects on postharvest quality of Hayward kiwifruit

Abstract

BACKGROUND: Late-season foliar application of mineral nutrients is a strategy to achieve higher flower quality, acceptable fruit set and yield in the following spring. However, these treatments may affect current fruit quality and storability. OBJECTIVES: This study was conducted to consider the effects of different late-season mineral foliar treatments on postharvest quality of kiwifruit that was presented on vines at the time of foliar application. METHODS: Mineral foliar treatments were included urea (0.25%, 0.5% and 1%), zinc sulfate (1000, 1500 and 2000 mg.l–1) and boric acid (500, 1000 and 1500 mg.l–1) alone and combined treatments with urea (0.25%) + H3BO3 (500 mg.l–1) + ZnSO4 (1000 mg.l–1); urea (0. 5%) + H3BO3 (1000 mg.l–1) + ZnSO4 (1500 mg.l–1); urea (1%) + H3BO3 (1500 mg.l–1) + ZnSO4 (2000 mg.l–1) and control group (only water). To determine the best foliar application time in late-season, spraying was done at three different times including September 17, October 7 and October 28 and the fruits postharvest traits were analyzed at harvest time and 90 days after storage. RESULTS: In this study, foliar applications of mineral compounds was not shown any negative effect on the fruits quality parameters, but also in some of these treatments positive effect of foliar application were detected on measured parameters. The best performance of foliar application on visible parameters was observed on September 17. Meanwhile, the soluble solids and titratable acidity content was not affected at harvest and after storage time by foliar treatment. Results of this study indicate that dry matter, color indices, and phenol levels were not affected by experimental treatments after storage time. In general, October 7 was indicated as the best spraying time regards into ascorbic acid content and antioxidant activity. CONCLUSION: Based on our findings, mineral foliar application can improve appearance characteristics, and nutritional value of kiwifruit that presented on vines at the foliar application time, on September 17 and October 7, respectively.