Tree structure and shaping and pruning techniques of jujube

Tree structure and shaping and pruning techniques of jujube

1 characteristics of branches and buds related to shaping and pruning

Generally speaking, there are 3 kinds of branches and 2 kinds of buds in jujube. The branches are jujube head (developmental branch), jujube strand (fruiting mother branch) and jujube hanging (fruiting branch) (figure 1). The buds are divided into main buds and secondary buds.

Fig. 1 three branches of jujube

Jujube head is the only important vegetative branch that can be elongated and enlarged. The growth and development of jujube head branch depends on the height of tree, the enlargement of crown and the formation of fruiting branch. The jujube head branch of jujube tree is not a single branch like apple and other fruit trees, but secondary branches grow from each node as soon as they germinate. The first and second segments of the jujube head branches are detached or semi-lignified jujube hangers, and the secondary branches of the other nodes are permanent branches bent in zigzag shape. Each node of the secondary branch is covered with jujube strands (fruiting mother branch), so it is called fruiting basal branch. The first 1-2 nodes of secondary branches have no thickening ability and will generally die. The annual growth of jujube head depends on tree age, tree potential and location. Generally, the annual growth of young and strong trees can reach 100~150cm, and that of mature trees can reach 40~50cm. Backbone branches (the backbone branches of jujube trees are formed by continuous extension of jujube head branches.) The growth of the jujube head at the apex and the periphery of the crown is generally larger, and the new jujube head tends to grow more when it is in the dominant position or when it is stimulated by truncation. When the tree is weak to a certain extent, the jujube head branch can not even grow decent secondary branches. Most of the head branches of this kind of jujube have no use value and should be thinned out generally.

Jujube stock is the main fruiting part of jujube, which is mainly born on the nodes of secondary branches. There are one to several fruiting branches (jujube hanging) on the jujube stock, and the jujube stock is called the fruiting mother branch. In fact, jujube stock is extremely compressed jujube head branch, its structure and jujube head is the same. It's just that the leaves are metamorphosed into scales, and the jujube hanging extracted is equivalent to the secondary branches, and the main buds between the axils of the leaves are latent. The annual growth (lengthening) of jujube stock is very small, and several jujube hangers are pulled out, which shows that jujube stock has been elongated by several segments. The terminal bud of the jujube stock and the main bud hidden on the side sometimes reverse and grow into a stronger jujube head branch. It is further explained that the structure of jujube head branch and jujube stock is the same.

Jujube hanging, that is, detached branch, is the fruit branch of jujube. From the beginning of germination, the flower buds differentiate in the leaf axils with growth, except for the single flower at the base of 1-2 nodes of jujube hanging, the other nodes are inflorescences with different number of flowers.

The buds of jujube are divided into main buds and secondary buds, and the division of labor is clear. The main buds give birth to jujube heads and strands, and secondary buds produce secondary branches and jujube hanging. The main buds can lie dormant for several years, while the accessory buds are precocious and germinate with generation. Therefore, the derivatives of accessory buds (secondary branches and jujube hanging) can only be seen on jujube trees, but not accessory buds. It is worth noting that the top bud of jujube head branch not only has the shape of bud, but also full and full. the resulting jujube head branch is the basis for tree growth, backbone branch and crown formation. If you don't need this branch to elongate again, just cut off the terminal bud.

2 the tree structure and shaping and pruning techniques of jujube

The structure of jujube tree is simple. Generally, there is a trunk with high 100~150cm (except for jujube orchard for dense planting); there are 3 or 4 or 4 or 5 backbone branches (or main branches) on the top of the trunk. A number of fruiting branches formed by jujube head branches are directly planted on the backbone branches. These fruiting branches are attached to both sides of the backbone branches, alternating in length, oblique or spreading. The elder is formed by the continuous elongation of jujube head branches for 2 to 3 years, with a length of about 100~150cm. The short one is formed by the one-year-old jujube head, and the length is about 50cm. Results the density of branches depends on the space of the tree. The principle is at least 30cm spacing between branches to maintain good ventilation and light transmission conditions.

2.1 fixed drying

Jujube should not be cut and dried after planting. The reasons are as follows: first, after planting, it depends on the height of the jujube branch at the end and the expansion of the crown. Second, because the newly planted root system has not yet recovered its absorption function, the growth and branching all depend on the storage and nutrition of the seedlings. If truncation forces the axillary main buds to sprout and branch, it will aggravate the nutrition contradiction and make the jujube head branch grow poorly. According to the experiment of jujube farmers in Cangzhou, Hebei Province, the jujube tree with dry diameter 3cm can only send out 3-4 jujube heads at the same time, and the jujube tree can reach the dry diameter 3cm only 3-4 years after planting.

The suitable method for fixing the trunk of jujube is to "drive out" the trunk, that is, to remove the secondary branches from the bottom up year by year until the height of the trunk is reached (if there are jujube head branches on the base of the tree and on the trunk in this period, they should be removed). In order to speed up the establishment of the garden, large seedlings can be cultivated in the nursery. Large seedlings with branches and fixed trunks can be planted in the future, and the slow seedlings can enter the fruiting stage more quickly.

2.2 Culture of backbone branches

When the jujube tree grows to a certain stage, the jujube head branch will sprout in the crown, as long as the jujube head branch grows healthily, the orientation is suitable, and the jujube head branch is extracted from the base of the secondary branch on the central axis. For the new jujube head branch, the terminal bud should be well protected, and the weak secondary branches should be thinned, so that the jujube head can extend and grow year after year, and then form a robust backbone branch. It is worth noting that the jujube head branches sprouting on each node of the secondary branches can not be cultivated into backbone branches. Because the thickening of the secondary branch is not consistent with the jujube head branch, the secondary branch segment is easy to break and the cultured backbone branch is broken.

Another method is to promote the first branch of jujube, and then grow into backbone branches. During the dormant period, the jujube head branch in the central position is cut short, the cutting mouth is at the thickest secondary branch, and the two secondary branches under the cutting mouth are thinned (the second secondary branch is the position of the backbone branch in the future). In the coming year, there are usually two jujube head branches, the first one is erect and continues to extend, and the second oblique branch is cultivated into a backbone branch. It must be emphasized that while cutting the jujube head, the secondary branches under the cut mouth must be thinned at the same time, otherwise the main bud will not sprout and produce jujube head branches. This is what jujube farmers said, "Jujube is the result of one scissors, two scissors grow branches." [Jishan Huayao]

2.3 Culture of fruiting branches

The fruiting branches of jujube are equivalent to the large and medium fruiting branches of apples, which are oblique on both sides of the backbone branches. The large and small fruiting branches on the backbone branches are also formed by jujube head branches. If a jujube branch grows to 40~50cm, the terminal bud (or together with the top 1-2 secondary branches) is removed, and a stable medium-sized fruiting branch is formed. If a jujube head elongates continuously for 2 ~ 3 years and then goes to the top bud, a larger fruiting branch will be formed. The fruiting branches arranged on the backbone branches are required to be scattered and orderly, not sparse and dense, and maintain good ventilation and light transmission conditions. In the young tree stage, it is better to be rare than dense. The jujube stock on many fruiting branches is the main fruiting position. Therefore, the status of fruiting branches is closely related to high yield or not.

2.4 methods of pruning jujube trees

To sum up, pruning jujube trees is mainly using thinning branches and truncation techniques. The useless jujube head branches should be removed every year from the young tree stage to the fruiting stage, especially the jujube head branches which affect the growth of backbone branches in the crown and the scenery outside the crown should be removed. As a result, the ineffective secondary branches at the base of the branches should also be thinned in time.

There are two situations that need to be truncated: first, when the jujube head branch does not need to be extended and expanded, as long as the terminal bud can be cut off. Second, when the tip of the branch is weak and drooping, there will be a new jujube head branch sprouting in the dominant position, and the sagging branch segment will be cut off at this time, that is, the old branch will be renewed. In addition, picking the heart of the jujube in time in the young stage can enrich the main buds at the base of the secondary branches, and cutting short and thinning the secondary branches in winter can promote the development of robust jujube branches, thus accelerating the formation of the crown. In addition, if we can remove the 1 ~ 2 nodes at the top of the secondary branch and pinch off the 2 ~ 3 nodes at the top of the jujube at the same time, it can increase the fruit setting rate and increase the fruit, which can be used as an effective measure for early high yield of young trees.