Published online by Cambridge University Press: 12 October 2012
Introduction. The Chinese jujubetree always presents some unfavorable performances because its vegetativegrowth is very vigorous. Our study was conducted to apply root pruning totest whether it can effectively inhibit the vigorous vegetative growthby regulating the competitive ability of the root system for waterand nutrients. Materials and methods. For our experiment,roots were cut at three different distances from the trunk (light,moderate and severe root pruning) on both inter-row sides of jujubetrees to the depth of 20 cm. Roots of control jujube trees werenot pruned. Then we determined for three years the competitive indicatorsof Chinese jujube trees including the length, number and thicknessof primary branches; photosynthetic characteristics and nutrientconcentrations of leaves; hormone contents in the jujube head, flowernumber and fruiting percentage, yield, and fruit quality. Resultsand discussion. In the early stage after root treatment,root pruning decreased lots of indicators such as concentrationsof nitrogen, phosphorus, and potassium in leaves, photosynthesis, transpiration,stomatal conductance, and intercellular CO2 concentrationof leaves, relative to the same indicators as the control group. Withthe gradual emergence of new roots, these indexes appeared to have adversepatterns with respect to those in the early stage after root pruning. Comparedwith the control, root pruning significantly decreased the lengthand number of primary branches and flower number, but thickenedprimary branches, enhanced fruiting percentage and increased the amountof ethylene release of the jujube head in the whole experiment.Fruit quality was improved with root pruning, as indicated by increasesin vitamin C and total sugar and a decrease in titrable acidity.No effects of root pruning were noticed on yield. From our results,we conclude that the removal of the root system at a distance ofthree times the trunk diameter (severe pruning) from the trunk isthe most effective in regulating the competitive ability of theChinese jujube tree.