Relationships among mineral nutrition,ethylene and post-harvest physiology in apples on six rootstocks

The relationships among several mineral elements of August-sampled leaf October-harvested fruit, maturity and post-harvest quality factors of ‘Starkspur Golden Delicious’ apple trees grown on Seedling, Malling (M) 1, Malling Merton (MM) 106, M 7, Oregon Apple Rootstock (OAR 1) or M 26 in a high-density orchard during 1980–1982 were evaluated. Positive correlations were found between leaf N, K and P and fruit N, K and P, respectively, in most rootstocks. Leaf Ca did not correlate with fruit Ca; thus leaf analysis cannot be recommended for estimates of fruit Ca. Both leaf and fruit N positively correlated with fruit green color and negatively with fruit soluble solids in all rootstocks. Fruit Ca and fruit P were both negatively correlated with fruit soluble solids at harvest and after 6 months of 0°C storage for all rootstocks. The ratio of fruit $\text{N}\text{Ca}$ was positively correlated with internal ethylene in MM 106, M 7 and OAR 1, while fruit $\text{K}\text{Ca}$ ratio was positively correlated with titratable acidity in all rootstocks. Fruit Ca showed negative correlations with bitterpit, storage rot and field internal ethylene, but positive correlation with firmness. Yield was positively correlated with leaf and fruit N, Ca and Cu but slightly negatively correlated with B of those tissues. Higher yield was associated with lower leaf K concentrations. Fruit green color was negatively correlated with soluble solids and titratable acidity. Fruit dry matter was highly positively correlated with soluble solids and titratable acidity in MM 106, OAR 1 and M 26. Soluble solids at harvest were strongly predicted by pre-harvest dry matter.