Effects of root wrenching on leaf mineral content of Prunus avium and Castanea sativa seedlings

The roots of wild cherry (Prunus avium L.) and sweet chestnut (Castanea sativa Mill.) seedlings grown from seed in a nursery bed were cut by passing a wedge-shaped blade horizontally through the soil (wrenched) at 20 cm depth on 10 July (early) or 12 August (late) or on both dates. Nitrogen concentrations in leaves of C. sativa and P. avium seedlings were severely reduced by early or late root wrenching, and except for the early wrenched C. sativa, seedlings had not fully recovered by the end of the growing season compared with the controls. Phosphorus concentrations also were reduced in the leaves of both species by wrenching treatments, but were similar to those found in undisturbed seedlings by the end of the season. The effects of wrenching treatments on the concentrations of potassium, manganese, and calcium in leaves of either species were generally negligible. The reduction in concentrations and total foliar content of nitrogen and phosphorus caused by the wrenching treatments in leaves of these species did not have a negative effect on growth following outplanting.