ACTION DES FERTILISATIONS TARDIVES SUR LE GENÉVRIER (Juniperus chinensis ’Pfitzerana Aurea’) CULTIVÉ EN CONTENANTS

Abstract

Three-year-old plants of Juniperus chinensis ’Pfitzerana Aurea’ grown in containers were fertilized until August, September or October. Frost tolerance, water, mineral, total sugar, and starch content of shoots and roots were followed during the fall. Fall fertilization increased N and K content in the shoots and roots and accelerated shoot spring growth. Contents of P, Ca, Mg, Fe and Mn in the shoots and roots were not modified by the late fertilization regimes in the fall. Hardening of mature root and shoot was not affected by the prolongation of fertilization. Young roots did not harden. Water content of shoots decreased during hardening. The variability of root water content was too important to allow a detection of any reduction. At the end of fall, starch was almost completely hydrolyzed in shoots while it remained in appreciable quantity in roots. Total sugars increased more in shoots than in roots during the fall. The prolongation of fertilization had no influence on the total sugar or starch accumulation in shoots. Prolongation of the fertilization until October increased the starch and sugar content in roots.Key words: Juniperus chinensis ’Pfitzerana Aurea’, cold hardiness, growth, fertilization, water content, sugars, starch