The effect of pre- and postharvest calcium applications on the postharvest quality of Pinkerton avocados

Abstract

One of the problems facing South African avocado producers is that of poor postharvest quality in avocado fruit. This is extremely evident in fruit which has been stored at low temperatures and is particularly acute in the Pinkerton cultivar. Research in avocados, as well as other crops, has shown that internal fruit disorders are directly related to low fruit calcium levels. Despite a large amount of evidence for this relationship, little has been done to address this problem in avocados. In order to rectify this situation, a trial was set up to establish the effects of both preharvest and postharvest calcium applications on the quality of Pinkerton avocados. What distinguishes this trial from similar work in the past is the use of new calcium products formulated specifically for maximum uptake and translocation, with a minimum of phytotoxicity. The series of trials carried out this season indicates that a number of benefits are to be derived from calcium applications. These include firmer fruit, a reduction in both external and internal physiological disorders and a decline in certain pathological disorders. However, the work also indicates that other factors play a role in fruit quality and that these factors may override the advantages derived from calcium applications. One such factor is fruit maturity. The work indicated that preharvest applications are more effective early on in the development of the fruit rather than just before harvest. It was also seen that postharvest calcium applications can provide a means for improving fruit quality. While there is still considerable work to be done in this field, it has been shown that calcium applications provide a practical and effective means of improving avocado quality.