The same tree species, different branches and bearing directions have different degrees of difficulty in flowering and fruiting. Long vegetative branches grow for a long time, consume more nutrients, accumulate less nutrients, and are not easy to bloom; Short and medium branches stop growing early, accumulate more nutrients, consume less nutrients, and are easy to flower. In the same branch, the difficulty of flower formation and the number of flowers are different with different growth ability, location and extension direction. In addition, the opening angle of branches is different, and the flowering results are also different. Therefore, in order to promote flowering and fruiting, you can leave more branches and cut them lightly for a long time, and some branches can even not be cut; Changing the extension direction of branches can slow down their growth and promote the growth, flowering and fruiting of short and medium branches; For example, in order to promote the growth and accelerate the expansion of the crown, it can be cut again appropriately to reduce the total number of branches and promote the growth of branches; For the big trees entering the full fruit stage, it is necessary to prune them, maintain an appropriate proportion of fruiting branches, preparatory branches and regeneration branches, maintain the balance between growth and fruiting, and extend the full fruit stage; For aging fruit trees, it is necessary to renew and rejuvenate to maintain economic output until the whole garden is renewed.
The second is to improve the lighting conditions of trees. The length and intensity of light have great influence on fruit yield. Among deciduous fruit trees, peaches and apples like light the most, followed by grapes, pears and chestnuts, and persimmon trees are more tolerant to shade. The results show that the condition of flower bud formation is that the short branches must have more than 50% available light, so that half of the short branches can form flower buds. However, most fruit trees without pruning have closed crowns, and the internal illumination is lower than 30% of the natural illumination, that is, lower than the light compensation point. Therefore, the nutrition made by these leaves is only for their own consumption, and sometimes it is not enough, so it is difficult to bear fruit. Plastic pruning can improve the efficiency of photosynthesis of fruit trees, such as choosing suitable tree shape, widening the angle of backbone branches, reducing the number of backbone branches, reducing the height of trees and the thickness of leaf curtains. It can improve the lighting conditions and increase the effective leaf area; By reasonably increasing fertilization, improving leaf quality and photosynthetic efficiency and prolonging photosynthetic time, the accumulation of photosynthetic products can be increased, which is beneficial to flowering and fruiting. For example, for young trees and flourishing trees, light pruning, long planting, multi-branching, changing the extension direction of branches and adjusting the density of branches can effectively improve the light conditions of trees, enhance the photosynthetic efficiency of leaves, reduce ineffective consumption, increase the nutrient accumulation of trees, and be conducive to flowering and fruiting and increase early yield; However, if several young people cut and put them for a long time, there will inevitably be bad phenomena such as branch cross, leaf curtain thickness and poor lighting conditions, which will affect fruit yield, quality and economic benefits. On the other hand, if replanting is carried out year after year, the light conditions of trees can be improved, but due to the overall weakness, too fast nutrient growth, too long branches, insufficient nutrient accumulation in trees, difficulty in flowering and fruiting, and often low yield.
The third is to improve the nutrition of trees. Plastic pruning can improve the metabolic capacity of trees and improve their nutrition. The storage nutrients in fruit trees are basically carbohydrates and nitrogen-containing substances, and their content and proportion have great influence on the growth and fruit of trees. The research results of Fruit Research Institute of China Academy of Agricultural Sciences showed that five-year-old Redjade apple trees were pruned in early April. Two weeks later, it was found that the contents of nitrogen and water in pruned tissues were much higher than those in untrimmed tissues, while the contents of starch and sugar in pruned branches were lower than those in the control. This shows that pruning changes the nutritional composition of fruit tree branches, which is beneficial to the formation of flower buds and early yield improvement.
Correct application of pruning technology, especially for big trees in full fruit period, can obviously improve their light conditions, increase the photosynthetic efficiency of leaves, especially improve the nutritional status of leaves in canopy; For trees with many flowers and weak vigor, cutting off some flower buds can reduce nutrient consumption, increase nutrient accumulation of the whole tree, increase the area of the whole leaves and the total number of roots, and promote the growth and development of the whole tree.
Pruning of fruit trees in summer also has obvious influence on the nutrient content of branches. The summer pruning experiment of 10-year-old Jin Shuai apple was conducted by Hebei Fruit Research Institute. The results showed that both girdling and twisting the top could increase the accumulation of organic nutrients in the branches, promote the transformation of C/N ratio of the tree to the direction favorable for flower bud formation, and thus promote the flowering and fruiting of the summer pruning zone.
Perennial fruit trees have accumulated a lot of storage nutrients. In the process of pruning, thinning or shrinking branches will undoubtedly take away some stored nutrients. Therefore, the degree of pruning should be limited to a minimum as far as possible, and the cut part should be the underdeveloped part of storage tissue. Therefore, pruning in summer and autumn should be used to the maximum extent, and the amount of pruning in winter should be reduced as much as possible, and the pruning time in winter should be arranged after the nutrient return of trees.
Tapping or short pruning temporarily reduces the synthesis and supply of endogenous hormones and reduces or eliminates the inhibitory effect of hormones on lateral buds, so it is beneficial to lateral bud germination. The earlier the topping in summer, the greater the secondary growth. Picking grapes before and during flowering can obviously improve the fruit setting rate.
Circumcision or girdling above the bud eye can cut off the downward transport channel of hormones, obviously inhibit growth, and promote bud eye germination and flower bud differentiation.
The content of auxin in vertical branches, horizontal branches and drooping branches decreased in turn, so the downward buds were not easy to germinate, while the back buds were easy to germinate strong branches. In the process of pruning, pulling branches, bending branches or twisting tips will also affect the transport and distribution of hormones. After pruning to improve the lighting conditions, the delivery speed of hormones is also accelerated.
Pruning can also improve the activity of enzymes and produce catalase, which can eliminate the harm of hydrogen peroxide produced during metabolism to trees, thus improving the metabolic ability of fruit trees.
Fourth, it affects the distribution and transportation of tree nutrients. The research results at home and abroad show that the growth of fruit trees is directly related to the content, species, distribution, transportation and hormones of nutrients in trees. Reasonable pruning can regulate the distribution and utilization of nutrients, thus regulating the growth of fruit trees, so that they can not only promote the robust growth of trees, but also blossom and bear fruit normally.
The results showed that the content of nitrogen in apple short branches was high and the content of carbohydrate was low. Fruitless short branches have low nitrogen content and high carbohydrate content; In twigs, the contents of nitrogen and carbohydrates are low. The observation results show that the short branches with high carbohydrate content are easy to form flower buds, while the short branches with low carbohydrate content are not easy to form flower buds, so the twigs are difficult to blossom and bear fruit.
Pruning fruit trees in winter can increase the water content and nitrogen content of fruit tree branches. After pruning, the nitrogen content of 1 year apple increased. After pruning 2-year-old branches, the nitrogen content decreased; After cutting short branches, the nitrogen content and water content of new shoots germinated by cutting sections increased obviously. However, if the pruning amount is too heavy, the carbohydrate content tends to decrease. Therefore, the pruning amount of young trees should not be too heavy, otherwise the nitrogen content of branches will increase and the carbohydrate content will decrease, which will lead to excessive vegetative growth, difficult to form flower buds, delay the fruiting period and affect the early yield and economic benefits.
Pruning in summer also has obvious effect on nutrient content of branches. Two days after grape coring, the nitrogen content and carbohydrate content of new shoots increased. Therefore, timely stone removal of grapes can effectively control vegetative growth, increase nutrient accumulation and improve fruit setting rate.
The transportation organization of fruit trees is similar to irrigation channels. If they are unobstructed, they will transport more nutrients, and the trees will grow strong, with more branches and leaves, and will soon become thicker. On the contrary, they grow weaker, have fewer branches and leaves, and gradually become thicker. 1 year after pruning for many times, pruning such as changing the head with back branches, bending dry and adding branches all affected the growth and thickening of trees because of many obstacles to nutrient transportation. Pruning measures such as girdling, girdling and torsion shearing are also due to temporarily destroying the transportation organization of branches, changing the original transportation direction of nutrients and water, improving the local nutritional status, slowing down the vegetative growth of trees, promoting the germination of short branches and the formation of flower buds, which is conducive to early fruiting and high yield.
The growth and fruiting of fruit trees, as well as the distribution and operation of nutrients in trees, are also related to endogenous hormones. Under natural conditions, there are more hormones at the tip of new shoots, which can inhibit the germination of lateral buds. However, if the top of branches is cut off to eliminate the inhibition of endogenous hormones on lateral buds, the germination of lateral buds can be promoted. If the upper part of the bud is cut off or the branches are girdled, the downward transport channel of endogenous hormones at the top of the branches is interrupted, and the lower lateral buds can also be stimulated to germinate. In addition, the opening of branches such as branches and curved branches will also affect the distribution and transmission of endogenous hormones. Therefore, these pruning measures can also promote the germination of lateral buds and increase the number of short branches, which is beneficial to flowering and fruiting.
Fifth, it affects the growth and fruiting of fruit trees. The growth and fruiting of fruit trees are mutually restricted and promoted. Under certain conditions, they can also be transformed into each other. Fruits need to be planted on branches with a certain leaf area. Only a certain number of branches and leaves can make enough nutrients for fruit growth and development to form flower buds for the next year to continue to blossom and bear fruit. Therefore, growth is the foundation of fruit, and fruit is the goal of culture. However, if the pruning is too heavy, the nutrition grows too vigorously, the number of strips is too much, and the consumption of nutrition is greater than the accumulation, it will affect the formation of flower buds or the growth and development of young fruits due to insufficient nutrition.
When pruning young fruit trees, because it can promote local growth, the pruning amount should not be too heavy, so as not to affect the formation of flower buds due to excessive nutritional growth. Lighter pruning measures should be taken, and more branches should be reserved appropriately, so as to promote its robust growth, rapidly expand the crown, increase the total number of branches and leaves and the number of effective short branches, and lay the foundation for high quality and high yield. At the same time, due to the relative independence between branches, some branches other than the main branches can be used to inhibit their excessive growth and promote flowering and fruiting by pruning measures such as pulling branches, girdling, girdling or pinching, and twisting tips. However, if the pruning is too heavy, the nutrient growth will be too vigorous, which is not conducive to flowering and fruiting.
After fruit trees enter the fruiting period, if there are too many fruits and too much nutrition consumption, it will inhibit the vegetative growth of trees, lead to nutrient loss, weaken the growth of trees or bear fruit in different years. Pruning can effectively adjust the proper proportion of leaf buds and maintain the relative balance between growth and fruiting. Improve ventilation and light transmission conditions; Increase the nutrient accumulation of trees and prolong the fruiting period. In actual production, pruning measures are often used to adjust the size of a year, that is, for large-flowered annual trees, too many thin and short fruit branches are removed, some medium and long fruit branches are cut short, and the ratio of leaves to fruit branches is increased to maintain high quality and high yield year after year.
For fruit trees entering the aging stage, attention should be paid to timely renewing the rejuvenated main branches, lateral branches and fruiting branches, making full use of long branches, renewing the backbone branches or cultivating them into fruiting branches, improving the nutritional status of trees, promoting nutritional growth and prolonging the economic fruiting period.
Sixth, improve the resilience of fruit trees. Once the fruit tree is planted, it will grow in one place for more than ten years, decades or even hundreds of years. Because of this long-term and persistent characteristics, fruit trees are more likely to suffer from pests and diseases and adverse environmental conditions than annual crops. Reasonable shaping and pruning can make the branches on the crown have reasonable configuration and suitable spacing, and maintain good ventilation and light transmission conditions; In the process of pruning, you can also cut off the branches of aging and pests in time, reduce the harm and spread opportunities of pests and diseases, make fruit trees suffer less or avoid their harm, enhance the resilience of trees and maintain stable production.
In addition, according to the site conditions of different orchards, it can be renovated into a tree shape adapted to local environmental conditions, so as to expand the planting scope and maintain normal output. For example, orchards built in windy areas or mountain air outlets can be made into low trees to enhance wind resistance; In winter cold areas, such as Heilongjiang, Jilin, northern Xinjiang and other places, fruit trees can be cultivated by creeping, which is not only convenient for covering soil to prevent cold and freezing, but also can make full use of geothermal energy to bear fruit early; When planting grapes in areas with dry summer and cool autumn climate, the trunk can be lowered, and the tree shape can be reduced. The whole grape can be shrub-like and densely planted.
All kinds of fruit trees can be reshaped to adapt to the local environment, enhance stress resistance, expand cultivation scope and obtain stable yield.
Seventh, increase fruit production. Reasonable pruning can adjust the growth of fruit trees in the whole garden and make it balanced, so as to give full play to the overall production capacity of fruit trees in the whole garden. If we cooperate with other agricultural comprehensive technical measures, every fruit tree in the whole garden will grow and develop in order, so that the production potential of each individual tree can be fully exerted and the balanced growth of output and output value per unit area can be guaranteed.
Reasonable pruning can not only give full play to the production potential of each fruit tree, but also give full play to the production potential of each tree and branch, so that the branches are distributed reasonably, configured properly, the affiliation is clear, the branches grow evenly, the trees are balanced and robust, and they do not restrict and influence each other, thus enhancing the growth potential of trees, prolonging the fruiting period and improving the fruit yield.
Reasonable pruning can also eliminate or alleviate the phenomenon of big and small years in fruit tree production. It can be seen from the production practice that orchards with extensive comprehensive management and neglected pruning often bear fruit in different years. Therefore, in order to obtain high quality and high yield year after year, it is necessary to carry out reasonable pruning on the basis of strengthening the comprehensive management of soil, fertilizer and water and comprehensive prevention and control of pests and diseases, so as to overcome or alleviate the phenomenon of fruit setting in different years.
Through shaping and pruning, a certain number of branches per unit area can be maintained, and an appropriate proportion of developing branches and fruiting branches can be maintained, so that they can be distributed reasonably, evenly and grow in a balanced way. At the same time, attention should be paid to fertilizer and water management and pest control, and attention should be paid to thinning flowers and fruits, which has obvious effects on overcoming the phenomenon of fruit bearing in different years, improving fruit yield and maintaining high quality and high yield year after year.
Eighth, improve the quality of fruits and increase the value of commodities. Reasonable pruning can make trees and dwarf rootstocks with different ages, different growth and different crown widths bear corresponding fruit yields. For each branch of a tree, a reasonable fruit reserve can be determined according to its planting position, extension direction, opening angle, thickness, occupied space and the results of previous years, so that it can be loaded reasonably between trees and between the main branches of the same tree. Only in this way can the fruit grow and develop evenly, with uniform size and high product quality. If the number of branches is appropriate, and good ventilation and light transmission conditions can be maintained, the fruits inside and outside the crown can get sufficient light, the red varieties can be fully colored, and the yellow or green varieties have smooth fruit surfaces without watermarks and rust spots. In this kind of orchard, the first-class fruit rate can reach more than 80%, while the external fruits such as pests, deformed fruits and small fruits can be reduced to less than 5%, or even lower or none. Such orchards are not only convenient for harvesting, but also conducive to graded packaging, storage and transportation after harvesting. The appearance quality of fruit is good, and the commodity value and economic benefit will also be improved.