“JONAGOLD” APPLE FRUIT QUALITY AS INFLUENCED BY FALL SPRAYS WITH CALCIUM CHLORIDE AT HIGH RATES

Abstract

The aim of the experiment was to examine the effects of fall sprays with calcium (Ca) as calcium chloride at high rates on ‘Jonagold’ apple (Malus domestica Borkh.) fruit quality. Trees were sprayed with Ca both in summer (9, 7, 5, and 3 weeks before fruit harvest) at a rate of 3 kg Ca ha−1and in fall (one week before fruit harvest) at rates of 8, 16, or 24 kg Ca ha−1. Fall Ca sprays resulted in leaf injuries and defoliation; however they had no effect on cold hardiness of one-year-old shoots. Fruit yield, weight, maturity at harvest, surface condition, and color were not influenced by Ca sprays during three consecutive years. Fruit Ca concentration corresponded with amount of Ca applied. In two of three years, summer Ca sprays decreased sensitivity of apples to bitter pit. Fruit sprayed with Ca both in summer and in fall had higher firmness and titratable acidity after storage and were more resistant to bitter pit and internal breakdown than controls and fruit sprayed only with Ca in summer. Apples sprayed with Ca in summer and in fall at the highest rate were the least sensitive to bitter pit and internal breakdown and were more resistant to decay than control fruit.