Complementary treatments for cutting and their effect on trees – Bending shoots
Bending shoots was already used in eighteenth-century palace gardens in order to form artificial crowns of trees. The effect of this treatment was known to be manifested by weaker growth of bent shoots. In commercial orchards, bending shoots began to be widely used in Italy in the early fifties in the formation of oblique palmets. At the same time, in Germany and the Netherlands, the cultivation of apple trees in spindle form began to spread, and in Belgium in the form of a free line. Also these crowns were formed using both cutting and bending of shoots. Soon, numerous experiments were undertaken to explain the impact of bending shoots on the growth of trees and their fruiting..
Shoots growing in the crown more or less vertically can be bent to an oblique position, horizontal or even downwards, as long as they are flexible enough. By bending the shoots, we change their position in relation to the gravitational force acting on them. The gravitational force acts on the plant causing its strongest growth in the direction opposite to the ground, that is, vertical. At the same time, the higher parts of the plant grow stronger than the lower parts.. This phenomenon is called gravitomorphism.
Shoot located in the crown vertically grows stronger than shoot located horizontally. If we bend the vertical momentum to the horizontal, then we will weaken its growth. The length of annual increments decreases on average from 1/4 into 1/3. The way the momentum branches also changes. Vertical shoot produces the strongest increments from apical buds. A shoot located obliquely gives out increments more or less even along its entire length. Momentum bent to the level gives the strongest gains at the base, weakest in the middle and slightly stronger at the apex. Momentum bent in the form of an arc or vertically downwards gives the strongest increments in this part, which is the highest, so at the top of the arch or at the base. The way the shoots branch depending on their position is shown in the figure.
The influence of the position of the shoot on the nature of its growth: a – horizontal momentum creates the strongest increments at the base; b — bent momentum in the form of an arc forms the strongest increments in the apical part; c – vertical shoot produces the strongest growths from apical buds; d – the diagonal momentum branches evenly along the entire axis.
By bending the shoots on a young tree, we can regulate the intensity and nature of crown growth. Bent shoots grow less well, while shoots that are not bent grow stronger. If we crush the side shoots in the crown, leaving a conductor, we stimulate it to grow very much. Bending shoots allows you to easily obtain crowns with a strong conductor, as well as weakening the growth of one part of the crown, so that other parts can develop.
Bending not only changes the position of the shoots, but also causes some anatomical changes in them. Conductive beams, found in bark and wood are partially crushed, and sometimes and interruption. Bent shoots have a difficult outflow of assimilates and at the same time the supply of mineral salts. The exchange of food between the bent shoots and the rest of the tree is hindered. In conditions, when a young tree grows intensively, these above-mentioned changes in his life processes exert a positive effect on the formation of flower buds.
If the shoots are bent in the spring or by the end of June at the latest, it is in July and August that flower buds form on bent shoots. Bending shoots accelerates the entry of young trees into the fruiting period.
In the previous chapter I highlighted the adverse effects of cutting on the fruiting of young trees. It turns out, that cutting can be replaced by bending shoots. On young trees, some shoots grow at an acute angle to the conductor and for this reason they are not suitable for boughs. In the past, such shoots were cut. Currently, we bend them to a horizontal position and leave them in the crown. A larger number of shoots in the crown results in higher fruit yields (table).
Table. The number of flower buds formed and the size of the fruit yield depending on the method of formation of the crowns of young apple trees
| Mclntosh | Wealthy | |||
| Method of forming crowns | catfish of flower buds to 5 year of life of trees | sum of yield up to 5 year of life of trees (Kg) | catfish of flower buds to 5 year of life of trees | sum of yield up to 5 year of life of trees (Kg). |
| Almost natural crowns formed by cutting | 339 | 14,1 | 205 | 16,5 |
| Almost natural crowns formed by bending shoots | 548 | 22,6 | 428 | 28,2 |
| Loose-pile crowns formed by cutting | 159 | 10,0 | 222 | 13,6 |
| Loose-pile crowns formed by cutting and bending shoots | 353 | 21,4 | 391 | 29,4 |
Bending shoots shortens the wait for the first crop. Apple trees grafted on rootstocks strongly growing and formed by cutting begin to bear fruit in 6 into 8 years after planting. The same apple trees formed by bending shoots begin to bear fruit in 3-5 years after planting.