Introduction. The Chinese jujube
tree always presents some unfavorable performances because its vegetative
growth is very vigorous. Our study was conducted to apply root pruning to
test whether it can effectively inhibit the vigorous vegetative growth
by regulating the competitive ability of the root system for water
and 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 jujube
trees to the depth of 20 cm. Roots of control jujube trees were
not pruned. Then we determined for three years the competitive indicators
of Chinese jujube trees including the length, number and thickness
of primary branches; photosynthetic characteristics and nutrient
concentrations of leaves; hormone contents in the jujube head, flower
number and fruiting percentage, yield, and fruit quality. Results
and discussion. In the early stage after root treatment,
root pruning decreased lots of indicators such as concentrations
of nitrogen, phosphorus, and potassium in leaves, photosynthesis, transpiration,
stomatal conductance, and intercellular CO2 concentration
of leaves, relative to the same indicators as the control group. With
the gradual emergence of new roots, these indexes appeared to have adverse
patterns with respect to those in the early stage after root pruning. Compared
with the control, root pruning significantly decreased the length
and number of primary branches and flower number, but thickened
primary branches, enhanced fruiting percentage and increased the amount
of ethylene release of the jujube head in the whole experiment.
Fruit quality was improved with root pruning, as indicated by increases
in 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 of
three times the trunk diameter (severe pruning) from the trunk is
the most effective in regulating the competitive ability of the
Chinese jujube tree.