Among them, Sorbus pohuashanensis is naturally spherical, without a central trunk, and the main branches are directly led out from the ground, and the main branches directly bear fruit groups. When applying cluster pruning, the main branches should be inclined upward by 40 ~ 60 degrees, and 3 ~ 4 lateral branches should be left on each main branch, extending outward by 70 degrees. The advantages of this tree shape are light pruning, quick forming, large crown and strong wind resistance. The disadvantage is that there are many main branches that stand upright. If it is not properly controlled, the top will grow vigorously, the crown will be dense, the lower part will be bald easily, and the resulting part will move outward.
Pruning should be based on the principle of "light pruning, combination of light and heavy, and suitable for trees". It is worth noting that our company is located in Huanren, Liaoning, where the temperature is low and the wind is strong in spring. Pruning of Sorbus pohuashanensis can be divided into two seasons: spring pruning and summer pruning. Pruning in spring should be carried out after the sap flows out, because the wind is strong in spring, the temperature is low and the temperature difference between day and night is large in Liaodong area, and premature pruning is easy to cause frostbite of trees.
This paper introduces the matters needing attention in the pruning of landscaping seedlings for your reference:
With the vigorous development of urban landscaping, pruning technology is more and more widely used in garden plants. The author thinks that the pruning of garden plants is not only an art, but also a science. It should not only show the beautiful ornamental effect of garden plants, but also play a role in regulating tree potential, promoting growth and improving plant stress resistance through the rational use of different pruning methods. Several problems that should be paid attention to in the plastic pruning of garden plants are briefly described as follows:
First, the pruning of street trees is only a shortcut, and the pruning of hedgerows is only a shortcut. The two pruning methods are not comprehensively used. Thinning and pruning are the two most commonly used methods to beautify plants. Thinning is to cut off the branches at the base, but only part of the branches, which has different effects on plant growth.
Thinning branches can make the interior of plants ventilated and transparent, and nutrients can be supplied to effective branches to promote the growth of the whole and mother branches. However, because the branches left after thinning still have terminal buds, the top advantage is strong, the new shoots grow slowly and there are many short branches. In addition, if the common developing branches are excluded but the ineffective branches are not excluded, the growth potential of the whole and mother branches will be weakened because of the decrease of growing points and leaf areas. On the other hand, due to the local storage nutrition of the remaining branches and the increase of the proportion of meristem, the conduction tissue is developed, which makes its stimulating effect on the lower lateral buds, especially the first bud under the cut, far more obvious than that of thinning branches, and the new shoots are strong in branching and vigorous in growth. Of course, because short pruning has obvious local stimulation on the germination of lower buds, the density of branches and tips increases rapidly, which weakens the illumination in the inner cavity of plants, thus affecting tissue differentiation and providing conditions for the occurrence of diseases and pests.
Through the above analysis, the author thinks that the pruning of urban street trees or hedges should not be limited to a single pruning method, but should make full use of their respective characteristics, correctly adjust the contradiction between plant growth and accumulation, and create a suitable biological state. Pruning street trees, on the one hand, should improve ventilation and light transmission conditions by thinning branches to avoid competition between overhead pipelines and trees. More importantly, it is necessary to promote the growth of new branches and quickly expand the crown by cutting short branches, and use the heterogeneity and orientation of cutting buds to guide and adjust the tree potential. In order to improve the ventilation and light transmission conditions inside the hedge, improve the fullness of branches and the ability to resist pests and diseases, and avoid the phenomenon of bare and dry under the hedge, it is necessary to cultivate regular geometric shapes through short cutting.
Second, the pruning of garden plants, especially street trees, lacks scientific standards, and the pruning intensity does not vary from tree to tree. Every street tree, even the same tree species, grows differently due to different environmental conditions. The author thinks that the pruning amount, that is, the number of branches and leaves to be pruned, should follow the basic principles of light pruning of young trees, heavy pruning of old trees, light pruning of strong trees and heavy pruning of weak trees.
Because the aboveground and underground parts of young trees are in the vigorous stage of centrifugal growth, the influence of pruning on the growth of young trees is highlighted by the dual effects of local stimulation and overall inhibition. First of all, pruning reduces the number of branches and buds, reduces the transpiration area and increases the root-shoot ratio in a certain period, thus improving the water supply and nutrient supply of the remaining branches and buds and promoting the local growth of new shoots. Pruning reduces the total area of leaves, delays the growth of new shoots, reduces the supply of assimilated nutrients by roots, weakens the growth of roots gradually, and eventually inhibits the growth of aboveground parts. The inhibitory effect of pruning on the overall growth of young trees will gradually appear over time. The heavier the pruning, the faster and more obvious the inhibition effect. For old trees, because of the long growth period, the crown has been closed, the branches in the inner chamber are messy, and the nutritional growth is gradually weakened. At this time, if reasonable pruning can be carried out, too many branches with low regeneration efficiency can be removed and pruned again, and the remaining branches and buds will get relatively more storage nutrients from the roots, thus improving the overall physiological activity of plants and delaying senescence.
The same is true of pruning strong trees and weak trees. Because pruning is similar to fertilization and irrigation, in the case of good soil fertility and moisture, it can be lightly cut or not, and if combined with heavy cutting, it will often produce too many branches. If the soil is short of fertilizer and water, it needs more pruning. What needs to be emphasized here is that heavy shearing and retraction often only promote the local growth of new shoots, but generally inhibit the growth of roots. Therefore, the heavy cutting of weak trees should be combined with nitrogen application to improve root nutrition and increase storage nutrients of trees, thus promoting the metabolism and growth of the whole tree.
Third, the grasp of seasonal pruning is not accurate enough, and the distinction between seasonal pruning and quantity is not strict enough Pruning of garden trees can generally be divided into winter pruning (dormant pruning) and summer pruning (growth pruning), except that hedgerows need to be pruned all the year round to maintain a certain ornamental shape. The so-called winter pruning refers to the pruning of deciduous trees from defoliation to germination or evergreen trees in winter dormancy. Summer pruning refers to all pruning except winter pruning.
Regarding the selection of pruning period, the author thinks that the pruning of deciduous trees is generally appropriate from dormancy to before severe winter. First, the nutrients in deciduous branches are transported downward to the stems and roots before entering the dormant period, and then transported from the roots and stems to the branches in early spring. After dormancy, pruning will reduce the number of branches and buds, make intensive use of stored nutrients, strengthen the growth of new shoots in the coming year, and the terminal buds near the cutting mouth will be in an advantage for a long time. Secondly, before the arrival of severe winter, there is still a period of time from pruning to germination in spring. The redistribution of nutrients can promote the differentiation and germination of cut buds, strengthen the apical dominance, promote growth and reduce branching. Pruning of evergreen trees is generally suitable after severe winter and before spring seedlings sprout. First of all, many evergreen trees are weak in cold resistance and pruned too early. The cut caused by pruning makes the cut buds and nearby tissues vulnerable to frostbite, which is not conducive to wintering. Secondly, the nutrient content of evergreen leaves is high, but it decreases with the increase of leaf age, especially before defoliation, and most of them are reused. Therefore, before the spring shoots are pulled out, the old leaves are the most, and many old leaves will be pruned when they fall off, so the trees store enough nutrients and lose the least nutrients.
Let's talk about summer pruning. The remarkable difference between summer pruning and winter pruning is that it acts on active leafy plants and has a much faster and more obvious effect on the balance of nutrients, water and hormones and the relationship between organs than winter pruning. Theoretically speaking, dimming, adjusting branch density and adjusting load are the most intuitive, accurate and reasonable only in summer. Unfortunately, many cities are often unable to carry out summer pruning in time because of the shortage of labor. In particular, in summer, because trees store less nutrients, and new leaves are reduced due to pruning, under the condition of poor fertilizer and water conditions, excessive pruning in summer will inhibit the growth of plants, which is not conducive to the safe overwintering of plants and the growth of the next year. Of course, if the fertilizer and water conditions are good and the plants grow vigorously, summer pruning can promote the development of secondary branches and expand the leaf area, and the photosynthetic efficiency in the later stage is good, which is not necessarily inhibition, but will help to expand the crown, complete the plastic task ahead of time and reduce the pruning amount of winter pruning.
In a word, the pruning of garden plants must be guided by the basic theory of plant physiology, combined with the specific growth environment conditions of plants and the requirements of green landscape, formulate high-quality and low-consumption pruning indicators, adopt scientific methods and means, provide the best way for the growth and development of plants, and constantly explore and improve them in practice.