| The effect of different degree of pruning in modifying tree forms on growth, fruiting and photosynthetic ability were conducted with 10-year-old Red Fuji apple/M26 in 2002-2004, in which orchard with tree spacing 3 X 2 m is located at fruit grower Bai Jingcheng's orchard at Dingliu village, chengguan township, Sanyuan county, Shanxi province. The results showed as the following:1. Very lightly pruning and lower light distribution in the canopy resulted in decrease of tree photosynthetic ability which are the important reason of lower fruit quality and biennial bearing. Modifying tree forms for decrease of the shoot density can significantly improve photosynthetic ability and fruit quality and maintain the good yield.2. Cutting trees in high density orchards is the most effect way to improve light distribution and fruit quality. In the high density orchards or tree canopy, the first idea of modifying tree forms was the intermediate cutting trees and the lower branches in the leave trees by lightly pruning for increasing trunk height. The result showed that it is optimal to cut one tree every two trees in quincunx pattern.3. In high density and dwarf mature orchards, trees can be pruned to the slim spindle tree system by slightly thinning out vigorous lateral branch, cutting back of top leader of tree and thinning out the lower lateral branches for increasing trunk height and bending shoots heavily. In which major low branches are kept 80-100cm high, each tree is good to keep 8-12 lateral branches, 350-550 shoots, 120-180 middle and long branches above 5 cm temporarily. The suitable pruning in modifying tree form per tree is cutting 50%-60% of total shoots. It's better to keep 40-60 thousand shoots pre 667 m after winter pruning.4. There are many practical pruning problems in fruit production such nonstandard tree shape, very vigorous lateral branch and the narrow angle of tree branch. Therefore shifting gradually from the current tree shape to the target tree shape is the basic strategy. Bending shoots heavily and strengthening the pruning during growth season are necessary measurements. |
