Effects of rootstock and interstem on growth, productivity and mineral nutrition of 'Golden Delicious' apple trees

The influence of M.9 and M.26 rootstock and interstem/rootstock combinations M.9/M.7, M.9/M.111, M.26/M.7 and M.26/M.111 on the growth, productivity and leaf mineral nutrient of ten-year-old 'Golden Delicious' apple trees was evaluated. Mineral nutrient contents in leaves were compared with the standard values proposed for apple by various authors. The largest 'Golden Delicious' trees were recorded with M.26, M.9/M.111, M.9 and M.26/M.111, and the smallest with M.9/M.7 and M.26/M.7. The highest annual and cumulative yields were obtained from plants grafted on M.26 and the lowest from plants on M.26/M.7. Leaf contents of nitrogen, phosphorus and magnesium were at optimum levels in all grafting combinations. Potassium and calcium concentrations were below standard. Potassium was particularly low in the M.26/M.7 combination. Calcium was lowered when M.26 was used as interstem or rootstock. Slight variations among grafting combinations occurred for all elements contents. In conclusion, plant size and yield were affected by rootstock/interstem combinations rather than by nutrient contents.