Influence of apple rootstocks and k and n fertilizers on leaf mineral composition and yield in a high density orchard

Leaf mineral composition of ‘Starkspur Golden Delicious’ apple (Malus domestica Borkh.) on six rootstocks: Seedling, M 1, M 7, M 26, MM 106, and OAR 1 was monitored in a high density orchard. Two levels of K and N fertilizers were applied as soil treatments for the two‐year study. N, P, and K concentrations decreased while Mg and Ca increased in scion leaves on all rootstocks during the 1981 growing season. A higher demand for K and P was observed in fruit tissue as cropping increased in some rootstocks, leading to lower leaf concentrations of these elements. Scion leaves on OAR 1 had significantly lower Ca than on M 7, MM 106 and M 1 and lower Mg than on M 26. Those on MM 106 had the highest levels of Ca in both years. Scion leaves on OAR 1 had higher B than other rootstocks. Scion leaves on M 26 had significantly higher Mg than those on M 1, MM 106 and OAR 1. Leaves on M 7 had at least 8% more Cu than other rootstocks. Soil applications of K significantly decreased Ca and Mg concentrations while N applications significantly increased leaf N and Mg but decreased K and P. Yield per hectare was consistantly high in trees on MM 106 and low on Seedling rootstocks.