Some Effects of Ringing Branches on the Distribution of Dry Matter in Young Apple Trees

Abstract

Young apple trees, variety Sunset/M.7, were prepared with two similar branches. Rings of bark and blossoms were removed from selected branches at full bloom to give the 10 possible combinations of ringed and unringed, deblossomed and cropping branches. Ringing led to improved fruit set and some reduction in vegetative growth above the ring. The best crops and least reduction of vegetative growth on ringed branches occurred where the second branch was unringed. Dry matter was deposited in the branches in proportion to the leaf area and was virtually independent of treatment. Additional dry matter was deposited as fruit, trunk thickening, and root growth. Dry matter production per unit area of associated leaf was increased on ringed branches by enhanced fruit set and on unringed branches by the isolation of leaves on opposite ringed branches from the leaves supplying the rootstock. Differences could not be detected in the carbohydrate composition of the growing regions as a result of treatment although alterations in demand could cause a three-fold difference in dry matter production per unit leaf area. This indicates an ability on the part of apple leaves to increase dry matter production in support of enhanced growth.