1. Sparse layer shape: also known as sparse layer shape of trunk, abbreviated as sparse layer shape, it is a high-yield tree popularized and applied earlier in fruit production in northern China. Its tree structure is to leave a trunk and a central trunk, and the main branches are arranged in layers on the central trunk. The height of the tree is 5 ~ 5.5 meters, and the crown width is 5.5 ~ 6.0 meters. The trunk is 50 ~ 60 cm high, and the whole tree has 7 ~ 9 main branches, divided into 3 ~ 4 layers. Generally, there are 3 main branches on the first floor, 2 ~ 3 main branches on the second floor, and 1 ~ 2 main branches above the third floor. The main branches of the first layer are required to be large and symmetrical, and the yield accounts for about 70% of the whole tree. So we must work hard to cultivate. The main branches above the second floor become smaller in order to minimize the shading of the lower branches.
(1) Distribution of main branches: There are two forms for the requirement that three main branches on one floor are vertically arranged on the central trunk: adjacent and adjacent. Adjacent means that the main branches are arranged almost side by side with a small spacing, mostly within 10 cm. Proximity means that the main branches are closely arranged with a large spacing, mostly 10 ~ 20 cm. Therefore, the interlayer spacing is 20 ~ 40 cm. Adjacent main branches tend to weaken the growth of central trunk, which is mostly used for varieties with strong dryness, and it is easy to cause "neck-pinching" phenomenon for varieties with weak dryness. Adjacent arrangement can prevent this kind of "neck pinching", but it is easy to cause varieties with strong upper part and weak lower part and strong dryness. The distribution of the three main branches on the plane requires symmetry, and the azimuth angles of the adjacent branches are 65438+020 respectively. The opening angle between the main branch and the central trunk should be grasped in three angles: the base angle is 50 ~ 60, the waist angle is 70 ~ 80, and the sharp angle is 40 ~ 50. Generally, for orchards with sufficient fertilizer and water and vigorous varieties, the opening angle of the main branches can be appropriately larger; For varieties with insufficient fertilizer and water and weak growth, the opening angle of their main branches can be appropriately smaller. The spacing between the second layer and the first layer should be 80 ~ 100 cm. For the main branches above the second floor, the interlayer spacing can be appropriately increased, but the interlayer spacing, opening angle and branch expansion size should be reduced in turn. The upper branches should be staggered from the lower branches in plane distribution to avoid overlapping branches. In addition, it should be noted that the spacing between the upper and lower branches on the south side of the crown should be appropriately increased to facilitate the penetration of sunlight.
Sparse hierarchical tree structure
1 ~ 8 is 8 main branches of the same crown, and ① ~ ④ is 4 lateral branches of the same main branch.
(2) Configuration of lateral branches: The lateral branch is the lowest branch that directly bears fruit, and it belongs to the main branch, so it is required to be well cultivated on the premise that its branch must be shorter than the extension head of the main branch. In particular, the lateral branches on the first main branch in the lower part should be very particular, and the same main branch should be small in the upper part and large in the lower part, preferably distributed in layers. There are about two in each layer, which are equal and balanced in size and growth, obliquely symmetrical in direction and posture, and extend on both sides of the main branch slightly below the outer front. Therefore, the opening angle of the lateral branches relative to the central trunk should be greater than that of the main branches and the central trunk. The first lateral branch should keep a large distance from the central trunk, generally 50 ~ 60 cm. If it is too close, it is easy to make it too thick and form a "door edge". The growth of "door side" is easy to get out of control, which not only affects the normal growth and fruiting of the central trunk and main branches, but also easily forms cross-crowded disorderly branches, which affects the ventilation and light transmission conditions of the lower part of the crown. The second lateral branch and the first lateral branch are in the same layer, and the distance can be close, 30 ~ 40 cm. The third side branch is the second side branch, which should be far away from the second side branch, preferably 60 ~ 70 cm. The fourth lateral branch and the third lateral branch are on the same floor, and the distance can be nearly 20 ~ 30 cm.
Leaving a sparse tree structure
Therefore, the number of side branches on the first main branch is usually four, and the extension head of the main branch above it can bear fruit in the middle without weakening the growth ability of the main branch and side branches. Another method is to cultivate three lateral branches on the first layer of main branches, the first and second branches are arranged on both sides, and the third branch is cultivated under the back of the main branch, which is called "hanging down on both sides". However, the problem of this method is that the third vertical lateral branch often affects the penetration of external light, and often leads to the drooping and weakening of the extension head of the main branch because of too many fruits. Therefore, it is best not to cultivate the lateral branches below the back of the main branch. On different main branches at the same level, the side branches in the same order should be arranged on the same side and direction of the main branch as far as possible, and the odd and even branches should be arranged on one side in the order from bottom to top, so as not to affect the illumination of the crown when they grow up.
Sparse layer tree structure right
On the main branch above the second floor, the number and size of its side branches should be reduced in turn, and generally it is better to have two small and medium-sized side branches.
Evacuation layer shape is a tree shape commonly used in apple and pear producing areas in northern China in the past, and it can be reshaped in 10 ~ 12 years. It is characterized by better illumination, firm structure and easy realization of high and stable yield than the previous non-layered trunk and cone crown. However, because the central trunk is always reserved and there are too many main branches on the upper part, which affects the penetration of light, the middle and lower parts and the middle and inner sides of the crown are often poor in quality due to insufficient light, few fruits and chromatic aberration. So many fruit areas have made structural changes to this tree shape.