Đang chuẩn bị liên kết để tải về tài liệu:
Fruit growing in the tropics - Part 5

5 5.1 Training: pruning and bending Definition; the limited role of pruning in tropical fruits Pruning is the removal of unwanted growth in order to stimulate desired growth: something is removed to obtain a certain response. It follows that you cannot judge pruning solely by the looks of the tree immediately after pruning or by the amount of cut wood lying under the tree. | 5 Training pruning and bending 5.1 Definition the limited role of pruning in tropical fruits Pruning is the removal of unwanted growth in order to stimulate desired growth something is removed to obtain a certain response. It follows that you cannot judge pruning solely by the looks of the tree immediately after pruning or by the amount of cut wood lying under the tree. The quality of pruning can only be judged after the plant has had time say a growing season to respond. With experience you can predict the response to some extent. However growing conditions modify the tree s response to pruning. If tree vigour is moderate and the tree is going to bear a good crop the response is more predictable. Weak or excessively vigorous growth and failure to bear make the response to pruning more erratic. Experiments for instance in citrus usually show yield reductions following pruning and no clear-cut advantages. Figure 10 Bending down vigorous shoots that compete with the leading shoot. A shoot or branch can be placed in the desired position by bending. This is an attractive alternative to pruning particularly for young trees that still have to fill the allotted space. The trend to replace pruning to some extent by bending has led to a much more rapid increase in cropping volume for instance in tea pegging down and apple figure 10 . Training is a combination of bending and pruning. Training pruning and bending 41 Vines have to be trained on a supporting trellis. The cheapest way is to use live posts for a vertical trellis e.g. for pitahaya a T-shape trellis e.g. for passionfruit or an overhead pergola for grape . The overhead structure can consist of bamboo crossbars that support the wires. Agrodok 19 Agroforestry lists tree species that can be trained as live posts. People often think that pruning is needed for trees that grow too vigorously. This may be true for young trees but bending vigorous shoots or imposing stress as explained in Chapter 6 is usually a better .