Effect of Root Pruning and Irrigation on Growth, Water Relations and Gas Exchange in Pear Trees

Vegetative growth control is crucial for high fruit yield in pear orchards. The use of chemical growth retardants has been prohibited in Danish and European pear production due to increasing concerns about environment and chemical residues on fruits. Root pruning has been proven as a good alternative to control the vegetative growth of fruit trees substituting the use of chemical growth regulators. A field experiment was conducted in 2011 to investigate the effects of root pruning and different irrigation regimes on shoot growth, tree water status, leaf photosynthesis and fruit size and color in a pear orchard. The results showed that root pruning is very effective in controlling the vegetative growth of pear trees. In root pruned pear trees full irrigation and deficit irrigation did not stimulate additional shoot growth. Root pruning decreased the tree water status and stomatal conductance. However, leaf photosynthesis was not affected resulting in improved intrinsic water use efficiency. Root pruning resulted in lower fruit weight, size and less green color. Full irrigation and deficit irrigation tended to improve fruit weight and size in root pruned pear trees, and thus maybe used as an efficient tool to alleviate the negative effects of root pruning on fruit yield and quality.