Post-harvest disorders and mineral composition of apple fruits as affected by pre-harvest calcium treatments

Abstract

The effect of pre-harvest calcium sprays, CaCl2 and Ca (NO3)2, on apple (Malus domestica) N, P, K, Ca and Mg content, storability and incidence of physiological disorders (superficial scald, bitter pit, physiological spot) was studied using two cultivars, ‘Krameri Tuviõun’ and ‘Talvenauding’. In the first year calcium treatment did not reduce any physiological disorders or loss of marketable yield. In the second year calcium treatment reduced storage losses until four months after storage. Bitter pit in ‘Krameri Tuviõun’ was unaffected by calcium treatment, but physiological spot of ‘Krameri Tuviõun’ and superficial scald of ‘Talvenauding’ were reduced by calcium treatment in the second year. Both physiological disorders of 'Krameri Tuviõun’ correlated negatively with Mg and P content and Mg/Ca ratio in apples. Superficial scald of ‘Talvenauding’ correlated negatively with Ca content and positively with K/Ca ratio, N/Ca ratio and Mg/Ca ratio in fruits. The conclusion can be made that content of Ca and its ratios with other nutrients plays an important role in the development of superficial scald on ‘Talvenauding’ fruits, and increasing Ca content in fruit can therefore be recommended for improving post-harvest quality of this cultivar. Since bitter pit in 'Krameri Tuviõun’ was not reduced by calcium treatment, it would be worth trying other measures for this cultivar.