Contrasting the cracking phenomena in sweet cherries: positive effect of microelements addition (B, Fe, and Zn) to pre-harvest Ca- and Si-based spray treatments

Sweet cherries’ cracking caused by rainfall shortly before harvest is a major problem for sweet cherry production. We found that different pre-harvest sprays (Ca-, Si-based, and Ca+Si-based and enriched with B, Fe, and Zn) reduced at least by 50% the cracking index (CI) of ‘Sweetheart® Sumtare*’ and ‘Grace Star*’ sweet cher- ries. The highest effectiveness on CI reduction was found when B, Fe, and Zn were used simultaneously with Ca and Si (Experiment I). In a cultivar with lower susceptibility for fruit cracking (‘Early Bigi® BigiSol*’), all the treatments strongly reduced CI, but without any significant differences within treatments. Only minor changes of colorimetric CIE parameters of skin were found in treated fruits (Experiment II). Despite the positive effects of the applied treatments on CI, some cultivar-specific side effects on soluble solid content and fruit size implies that treatments should be carefully evaluated on the bases of the inherent differences between cultivars.