Influences of Root Pruning on Reproducion and Activity of Roots in Mature Tea Plants

Abstract

Regeneration and activity of roots after root pruning have been studied using mature (18-year old) tea plants grown in a field. The amount of the newly-developed white roots in a 20 cm deep-soil layer was greatest in the late September I plot (combination of hard root pruning and nitrogen application in late September every several years) followed by the late August I plot (light root pruning at every late August : the most conventional management) and late Autust II and late September II plots (combination of hard root and shoot pruning in late August or late September every several years). Root activity determined by an activable tracer method accurately reflected the degree of root reproduction. Root pruning and root-shoot pruning remarkably restrained subsequent shoot growth. These growth reactions of shoot and root to root pruning obtained through the present experiment resembled those in young tea plants. It was confirmed that root pruning is applicable as one of the techiniques for regenerating tea plants irrespective of age because root pruning promoted active reproduction of roots in mature plants. It was judged that the activable tracer method in tea plants is effective to grasp the root activity in soil layers at a practical level.