I, walnut branch types

Walnut tree branches are divided into fruiting branches and nutrient branches of two types

1, fruiting branches: bearing mixed buds of the branch is called fruiting branch, mixed buds more first born in the fruiting branch at the top of the mother and the upper sections, spring sprouting fruiting branches, bearing female flowers at the top of the fruiting branch results. Robust fruiting branches can then spawn short branches (end branches), most of the year can form mixed buds, early walnut can also be sprouted that year, the second flowering and fruiting. Late solid walnut fruiting branches are mostly embedded in the periphery of the tree crown, the interior is less, and the bore is more bare. Adult walnut tree crown peripheral branches bearing more mixed buds, the second year of its apical growth point are sprouting fruiting branches, so its branch growth is extended by lateral bud sprouting, is a typical type of coaxial branching, so that the surface of the crown becomes the most branched fruiting layer. Early solid walnut side bud fruiting ability is strong, inside and outside fruiting parts, the same three-dimensional space within the fruiting amount. The number and length of fruiting branches, often due to varieties, tree age, ground conditions, cultivation and management measures vary.

2, nutrient branches: where only the leaves do not flower and fruit branches, can also be called growth branches.

Specifically, it can be divided into developmental branches, intermediate branches, unproductive branches, secondary branches and male flowering branches.

①Developmental branch: by the previous year's leaf buds developed into a robust nutritious branch. The development branch is the basis for expanding the crown, increasing the nutrient area and forming fruiting branches.

2 intermediate branches: generally more born in the inner crown, in the case of insufficient light, the tree is weak, less than 1 week after the annual leaf stop growing, once the tree from weak to strong, it can be transformed into a mixture of buds and blossom fruit.

③Elongated branches: more by the crown bore dormant buds (or latent buds) sprouted into. The angle of the elongated branch is small and erect, the internode is long and not full. Through the control can be transformed into fruit-bearing branch group. Older trees use it to renew and rejuvenate.

④Secondary branch: early walnut has a second branch, three branches, and can blossom and bear fruit, late walnut second branch is less.

5 male flowering branches: for bearing male flower buds of weak branches, only the terminal bud for the leaf buds, not easy to form mixed buds, male inflorescences fall off, the terminal bud below the bare. Male flowering branches more bearing in the old weak tree or tree crown inner depression, the city introduced some early varieties of male flowering branches large amount. Too many male flowering branches is the performance of the tree is weak, and unnecessary consumption of nutrients to affect fruitfulness.

Two, walnut tree branch structure

Walnut tree branches and other tree branches in the structure of the obvious difference is that there is a very large hollow medulla; and, medulla with intermittent diaphragm. Diaphragm degree of sparseness and branch growth rate at the time related to the growth rate of fast growth rate in the medulla of the diaphragm sparse, slow growth rate in the medulla of the diaphragm denser. Because of the medulla, after the branch is cut off, the water loss rate is faster, in the cut off branches should be in the bud at the end of the bud to retain a more protective section, in order to prevent buds from drying out.

Three, the growth habit of walnut tree branches

The branches of the walnut tree have two growth peaks each year to form the spring and fall tips. Spring buds and leaves, the new shoots appear, with the rise in outside temperature, the new shoots accelerate the growth of the growth peak in early May, the daily growth of 3 -4 cm, in early June the first growth stops, the short branches and weak branches of the end of a growth in the formation of terminal buds, no autumn shoots. The second growth can be seen in the vigorous developing branches and fruiting mother branches, forming the fall tips. Over-exuberant branches or long branches of summer growth non-stop, or slow growth, spring and fall tip demarcation is not obvious.

Most areas of the walnut tree before the fruitful period, the branch elongation of the year in spring and fall two growth peaks, respectively, the formation of spring and fall tips. Generally after the spring sprouting, with the gradual increase in temperature, the growth of new shoots gradually accelerated. When the daytime temperature reaches 23 ~ 28 ℃, its growth rate reaches the maximum; when the daytime temperature exceeds 30 ℃, the transpiration of the branches and leaves increased, the soil water content gradually decreased, resulting in the top of the new shoots stop growing. Later, with the arrival of the rainy season, soil moisture is improved, the daytime temperature is also reduced, young trees and fruiting trees stop the growth of new top buds will sprout growth, the formation of autumn tips.

Walnut's strong fruiting branches after fruiting, from the fruit platform can also be very good fall tips, but will consume a lot of nutrients. When there is no lack of growing branches in the canopy, you can wipe off the fruiting platform secondary tips in time to promote fruit development.

Walnut growth branches in the rainy season, daytime temperatures below 22 ℃, elongation growth gradually slowed down, into the thickening growth stage. During this period, minor injuries on the branch cross-section can be quickly recovered. Therefore, young trees should try to pull branches to open the angle in this period.

Four, walnut tree branch injury flow

Walnut tree branches also have a special nature, that is, "injury flow". In a certain time frame, the branch of the xylem or phloem is injured, in the place of injury or leave the channel to the xylem (such as leaf scars after leaf shedding), will continue to flow out of the sap. This phenomenon is called "wound flow". There are two peak periods in a year, one is leaf drop, after winter, with the lowering of the temperature, the flow of injury increased, to the cold gradually decreased, before the bud is basically no flow of injury; the second is the bud, with the growth of the new shoots, the flow of injury and began to increase, gradually decreased after flowering, to the fruit ripening, the end of the flow of injury. Wound flow contains a large amount of mineral and organic nutrients, a large amount of wound flow will waste tree nutrients, weaken the tree.

Five, walnut tree branches cold resistance

Walnut tree branches are poorly adapted to low temperatures. Because of the different ages of trees, different degrees of branch filling, different types of branches, different degrees of adaptation to low temperatures. Such as 1 ~ 3 years old young tree annual branch frost resistance is the worst, in -20 ℃ that is the formation of frost damage; adult tree fruiting mother branch frost resistance is the strongest, can tolerate -30 ℃ of cold. Therefore, in cold areas, young trees planted after the first three years, to take anti-freeze measures every year, to protect young branches from frost damage, otherwise there will be above ground frozen every year, year after year, always renewed, always grow not a big tree phenomenon. This problem should also be noted when choosing the planting site, to avoid low-lying, frost-prone plots and areas with severe winters.

Six, walnut tree branch growth characteristics

In the whole walnut tree or a large branch, in the vertical position of the highest part of the buds or branches of the strongest growth potential, you can form a strong strong branch, in the vertical position of the lowest part of the buds or branches of the growth potential of the weakest and even can not be sprouted growth of the phenomenon, known as vertical dominance. In plastic pruning, we must take full advantage of this feature to regulate and maintain the balance of the tree, especially the balance between the main branches of the tree. Weak main branch branch head should be left higher, strong main branch branch head should be left lower; auxiliary branches, the height of the fruiting mother branch can not be higher than the height of the main branch head, otherwise, there will be a take over the main or the phenomenon of head change.

Natural growth, walnut tree trunk natural upward extension of the ability to be stronger, some can be as high as tens of meters, this stronger stem, is shaping to pay attention to. Densely planted, especially to prevent the tree height is too high to cause depression.