EFFECT OF SUMMER PRUNING TREATMENTS OF VIGOROUS APPLE TREES ON THE NUTRIENT CONTENTS OF FOLIAGE AND FRUITS

Vigorous trees of Cox and Jonathan on A2 rootstock and of Golden Delicious on M.4 were summer pruned on 7 June and 10 July respectively, and the effects compared with normal winter pruning.
Cuts by saw or pruning shears reduced the tree nearly to two-thirds of its previous yield capacity.
Because of very high initial leaf potassium values potassium fertilizer applications were discontinued.

Leaf phosphorus and leaf potassium contents were higher in summer pruned than in winter pruned trees but the effect on potassium in Golden Delicious, but in the Cox only during the last two years.

Fruit analysis showed higher nitrogen, phosphorus, potassium and magnesium content and a higher K/Ca ratio after summer pruning in the first treatment year (1973), whereas the actual fruit calcium values did not show any differences in that season.
In 1977 another fruit analysis was taken and resulted in rather different figures, namely lower nitrogen content in Golden Delicious, and lower nitrogen, phosphorus and magnesium values in Jonathan.
In this case fruits of both varieties had higher calcium contents, and, correspondingly, a lower K/Ca ratio in fruit tissue.
Cox was harmed by

Graphic available in full text only

Symposium on Mineral Nutrition and Fruit Quality of Temperate Zone Fruit Trees

G. BÜNEMANN, A. STRUKLEC

https://doi.org/10.17660/ActaHortic.1980.92.24