Effects of nitrogen and phosphorus on root and shoot growth of Cotoneaster divaricata Rehd. & Wils.

Abstract

Root and shoot growth rates of Cotoneaster divaricata were determined using a growing system of polyvinyl chloride pipe cylinders in which longitudinal sections could be removed for periodic root observations. Plants were fertilized with nitrogen (N), phosphorus (P), and potassium (K). N, as NH 4NO 3, was applied weekly at levels of 0, 250 or 500 mg/l and P, as H 3PO 4, was incorporated in the medium at levels of 0, 5 or 50 mg/l. K, as KCl, was maintained in the medium at a 150 mg/l level by soil tests conducted weekly. Shoot growth was increased after N application. However, no difference was observed between N levels. P increased shoot growth only at the highest N level applied. Although root growth was not increased by either N or P, high N levels inhibited root growth, whereas P stimulated root growth. No correlation ( r = 0.19) was observed between shoot and root growth.