CALCIUM ABSORPTION IN APPLES AND PEARS TREATED POSTHARVEST WITH CALCIUM, ZINC OR UREA

Postharvest use of calcium solutions to prevent bitter pit, Jonathan spot and internal breakdown of apples and internal browning of pears has now become general practice in Italy. However, the results are not always fully satisfactory and, in the belief that difficulty of penetration of calcium into the fruit is one of the main reasons for this, an investigation was carried out to establish whether the addition of other salts would facilitate penetration of calcium into the tissues. Calcium chloride was preferred to the nitrate because it appeared to be effective at relatively low doses (Betts and Bramlage, 1977) and did not incur the risk of causing an excessive nitrate content in the fruit. The choice of zinc chloride (Van der Boon, 1974) and urea as additives was based on their capacity to act as vehicles for carrying ions across tissues.