Teak variety updating method for rapid crown expansion and early high yield

Abstract

The invention relates to the technical field of agriculture and forestry grafting, in particular to a variety renewal method for rapid crown expansion and early high yield of teak, which comprises the following steps: S1, selecting top grafting seed change time, and selecting a scion variety and a stock; s2, selecting a top grafting part to implement top grafting; s3, performing post-grafting management and tree body water and fertilizer management after top grafting, wherein the post-grafting management comprises native branch (base stock and intermediate stock) management, scion and new shoot management and grafting film removal; according to the method, the three-dimensional and multi-directional grafting principle is adopted, grafting is conducted on different levels of branches of the branches, crown expanding can be conducted quickly, and flowering and fruiting can be conducted in advance, and production can be conducted in advance. Traditional teak top grafting and variety changing generally bear fruits after top grafting is conducted for 3 years, the teak can bloom and bear fruits after top grafting is conducted for 1 year through the technology, fruit bearing is conducted two years earlier than that of a traditional method, and economic benefits can be generated in advance.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural and forestry grafting, and in particular to a variety renewal method for grapefruits for rapid crown expansion and early high yield. Background Art

[0002] Pomelo (Citrus grandis (L.) Osbeck) is an evergreen fruit tree belonging to the genus Citrus of the Rutaceae family. There are now more than 2 million mu of pomelo in my country, which has caused a huge overcapacity in some pomelo varieties. For example, Guanxi honey pomelo, whether white flesh, red flesh or three red honey pomelo, can be put on the market before mid-August, with a price of 4.0-5.0 yuan / kg, but after September, as long as the pomelo from the main production area of ​​Pinghe, Fujian is on the market, the price will drop to 1.0-1.5 yuan / kg, or even unsaleable; the newly introduced Thai Ruby Green Pomelo at the same time was as high as 100-150 yuan / piece at the beginning of the market. Although the price of Ruby Green Pomelo in some production areas has now fallen to 15-20 yuan / kg, compared with Guanxi honey pomelo and other pomelo varieties, Ruby Green Pomelo has relatively high economic benefits. With such a large volume of pomelo, as the speed of new variety selection and breeding accelerates year by year, the timing of variety renewal becomes particularly important.

[0003] The main method of updating pomelo varieties is high grafting, which is to replace the branches of the original old varieties with excellent varieties to update the varieties. The stem cutting method is to use a low-ground grafting method and only retain 1 to 3 primary main branches for grafting. This high grafting method can achieve survival in one year, crown formation in two years, fruiting in three years, and high yield in five years. However, in today's period of rapid renewal and iteration of the citrus industry, the earlier the fruiting, the more obvious the competitive advantage and the more considerable the economic benefits of the harvest. Therefore, changing the existing high grafting method of pomelo, from fruiting in three years to flowering in one year, fruiting in two years, and high yield in three years, entering the high-yield period at least two years earlier than traditional high grafting, is of great significance to improving the market competitiveness and benefits of enterprises and fruit agricultural products. Summary of the invention

[0004] The purpose of the present invention is to provide a variety renewal method for pomelo that can quickly expand the crown and increase the yield early, so as to solve the problems of slow crown expansion speed, delayed fruiting and production of pomelo high-grafting replacement.

[0005] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0006] A variety renewal method for rapidly expanding the crown of pomelo and achieving early high yield comprises the following steps:

[0007] S1: Choose the time for high grafting, scion variety and rootstock;

[0008] S2: Selecting high grafting sites to implement three-dimensional multi-directional high grafting, the high grafting sites include the east, west, south, north and middle locations of the three canopy layers of the tree body;

[0009] S3: After high grafting, post-grafting management and tree water and fertilizer management are carried out, and the post-grafting management includes management of native branches and trunks (base stock and intermediate stock), management of scion and new shoots, and removal of grafting film.

[0010] Furthermore, Ruby Green Pomelo branches with full buds were selected as scions, and all Ruby Green Pomelo high grafting was performed using the short-branch single-bud grafting method. The original planting variety was Guanxi Honey Pomelo (scion) / Sour Pomelo (rootstock). After high grafting, the rootstock was Sour Pomelo, the middle rootstock was Guanxi Honey Pomelo, and the scion was Ruby Green Pomelo.

[0011] Furthermore, the high grafting parts in step S2 include the lower crown, middle crown and upper crown of the tree body; the three-dimensional is to ensure that new shoots can be quickly sprouted at every height of the crown, and the multi-directional is to consider the uniform distribution of new shoots in the future, so that the branches in a certain direction will not be too dense or too sparse.

[0012] Lower canopy high grafting: The height position is selected at the 2nd-3rd level branches on the main trunk at a height of 0.7 to 1.0 meters, and 3 to 5 branches are retained. Each branch is cut flat to retain 5 to 10 cm of original wood stakes to facilitate later grafting; branches with full buds of the Ruby Green Pomelo variety are selected as scion, and short branch single bud cutting grafting is used for high grafting; the remaining original branches are cut off at the branches to avoid competition for nutrients.

[0013] Middle canopy high grafting: the height position is selected at a height of 1.0m to 1.8m, and the branch level is 3-5; branch selection: select 8 to 10 healthy side branches, cut them flatly at 5-10cm, choose branches with full buds of Ruby Green Pomelo variety as scion, and use short branch single bud grafting method for high grafting; the rest of the original branches are cut off at the branches.

[0014] Upper canopy grafting: The height position is selected between 1.8 meters and 2.3 meters; the number of branches is 5-7 levels; branch selection: keep 3 to 5 high-quality branches, cut flat at 5-10 cm, select branches with full buds of Ruby Green Pomelo variety as scion, and use short branch single bud grafting method for high grafting. The rest of the original branches are cut off at the branches.

[0015] The grafting orientation includes the east, west, south, north and center orientations of each crown of the lower crown, the middle crown and the upper crown of the tree body; so that the crown is evenly distributed after the grafting, and branches exist in all orientations, so as to achieve the purpose of rapid crown expansion.

[0016] Beneficial effects of the present invention:

[0017] The invention realizes rapid crown expansion of pomelo trees by implementing three-dimensional multi-directional high grafting, and selects the lower crown layer (at a height of 0.7 to 1.0 meters), the middle crown layer (at a height of 1.0 to 1.8 meters) and the upper crown layer (at a height of 1.8 to 2.3 meters) for high grafting, and grafting is performed in five directions of each crown layer, namely, east, west, south, north and center. The uniform expansion of the crown at different heights and directions is ensured, and the problem of local sparseness or overcrowding caused by unidirectional growth is avoided.

[0018] The present invention optimizes the branching order of the lower, middle and upper canopies, realizes the early fruiting of pomelo fruit trees, and significantly shortens the time from grafting to high yield. According to different grafting heights, different branching orders are also limited. As the height increases, more branching orders are selected. For example, in the middle canopy, the height is 1.0-1.8m above the ground, at the 3-5th branch of the branch (the branching order is 3-5, i.e., the shoots are drawn 3-5 times), and the branching orders in this range are mostly fruiting mother branches at this height. Grafting at the branches in this range, the branches drawn in the current year can bear fruit after they are mature. If the branching order of height is not limited, it is possible to graft on the branches 1-2 at this height. The first and second new shoots drawn from such branches can only be backbone branches, and it takes a long time to bear fruit. Therefore, grafting according to the technical method of the present invention can bear fruit within 1 year after grafting, and the yield can reach 50-80kg / per column or more after 2 years after grafting.

[0019] Through these management measures to optimize the number of branches, the present invention effectively promotes the rapid development and fruiting of each canopy, ensuring that pomelo trees can bloom within one year, bear fruit within two years, and produce high yields in three years. This systematic management method significantly improves the utilization efficiency and economic benefits of the tree, allowing pomelo trees to enter the high-yield period two years earlier, significantly improving market competitiveness.

[0020] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for describing the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0022] Figure 1 It is a schematic diagram of the three-dimensional multi-directional high-joining replacement of the present invention;

[0023] Figure 2 This is a schematic diagram of the crown and flowering conditions of the tree after one year of high grafting and replacement of the present invention; (the crown is full and the amount of flowering is large);

[0024] Figure 3 This is a schematic diagram of traditional high grafting;

[0025] Figure 4 This is a schematic diagram of the crown growth two years after traditional high grafting; (the crown is sparse and not flowering). DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] The method for rapidly expanding the crown of pomelo and achieving early high yield in this embodiment comprises the following steps:

[0029] S1: Choose the time for high grafting, scion variety and rootstock;

[0030] S2: Selecting high grafting sites to implement three-dimensional multi-directional high grafting, the high grafting sites include the east, west, south, north and middle locations of the three canopy layers of the tree body;

[0031] S3: After high grafting, post-grafting management and tree water and fertilizer management are carried out, and the post-grafting management includes management of native branches and trunks (base stock and intermediate stock), management of scion and new shoots, and removal of grafting film.

[0032] In this embodiment, step S1 includes:

[0033] The time for high grafting is from January to February, which is conducive to the healing of the grafted part, slowing down the physiological activities of the tree, and reducing the risk of graft survival rate;

[0034] Choose Ruby Green Pomelo as the scion variety, and choose healthy, pest-free, high-quality mother trees to ensure its production potential; pick the scion within one week before the scion is picked, and place it in a cool place after picking, avoid direct sunlight, keep it moist, and prevent the scion from losing water;

[0035] The rootstock types used are sour pomelo as the base rootstock and Guanxi honey pomelo as the intermediate rootstock.

[0036] In this embodiment, the rootstock requirements include: strong growth, well-developed root system, strong resistance to stress; free from disease and insect pests to ensure that the growth is not affected after the scion is transplanted.

[0037] In this embodiment, the high grafting parts in step S2 include the lower crown, the middle crown, and the upper crown of the tree body; the three-dimensional is to ensure that new shoots can be quickly sprouted at each height of the crown, and the multi-directional is to consider the uniform distribution of new shoots in the future, so that the branches in a certain direction will not be too dense or too sparse.

[0038] Lower canopy high grafting: The height position is selected at the 2nd-3rd level branches on the main trunk at a height of 0.7 to 1.0 meters, and 3 to 5 branches are retained. Each branch is cut flat to retain 5-10 cm of original wood stakes to facilitate later grafting; branches with full buds of the Ruby Green Pomelo variety are selected as scion, and short branch single bud cutting grafting is used for high grafting; the remaining native branches are cut off at the branches to avoid competition for nutrients.

[0039] Middle canopy high grafting: the height position is selected at a height of 1.0m to 1.8m, and the branch level is 3-5; branch selection: select 8 to 10 healthy side branches, cut them flatly at 5-10cm, choose branches with full buds of Ruby Green Pomelo variety as scion, and use short branch single bud grafting method for high grafting; the rest of the original branches are cut off at the branches.

[0040] Upper canopy grafting: The height position is selected between 1.8 meters and 2.3 meters; the number of branches is 5-7 levels; branch selection: keep 3 to 5 high-quality branches, cut flat at 5-10 cm, select branches with full buds of Ruby Green Pomelo variety as scion, and use short branch single bud grafting method for high grafting. The rest of the original branches are cut off at the branches.

[0041] The grafting orientation includes the east, west, south, north and center orientations of each crown of the lower crown, the middle crown and the upper crown of the tree body; so that the crown is evenly distributed after the grafting, and branches exist in all orientations, so as to achieve the purpose of rapid crown expansion.

[0042] In this embodiment, the high grafting method in step S2 adopts the short branch single bud grafting method to perform the high grafting of Ruby Green Pomelo.

[0043] In this embodiment, the post-connection management in step S3 specifically includes:

[0044] Management of native branches and trunks: Within 25 days after high grafting, check the native buds and new shoots, and promptly remove the sprouted new buds to concentrate nutrients to promote the growth of the scion and avoid competition for nutrients with the native branches and trunks.

[0045] Scion and new shoot management: When the scion grows to 20-25 cm, pinch the top to promote the growth and branching of lower branches, and quickly expand the crown to form a high-yield structure.

[0046] Removing the grafting film: Observe the growth of new shoots, and remove the grafting film in time after the second-level new shoots mature, so as not to affect the delivery of nutrients and the growth of branches.

[0047] In this embodiment, the tree water and fertilizer management in step S3 specifically includes:

[0048] Water management: Carry out the first drip irrigation within 15 days after grafting, and then drip irrigation every 10 to 15 days. Adjust the irrigation frequency according to climatic conditions to keep the soil moist and the roots grow normally.

[0049] Fertilization management: Fertilizer should be applied to the soil and mixed with covering soil to avoid direct contact with the root system and reduce fertilizer damage.

[0050] In this embodiment, the fertilization management specifically includes: topdressing 4 times a year, the first time (spring shoot fertilizer) is in February and March, the fertilizer is a balanced compound fertilizer, wherein N: P2O5: K2O = 15: 15: 15, and 300-400 g / plant is applied in shallow furrows; the second time (late spring shoot fertilizer) is in late May, the fertilizer is a high nitrogen and potassium compound fertilizer, wherein N: P2O5: K2O = 20: 5: 20, and 400-500 g / plant is applied in shallow furrows; the third time (strong shoot fertilizer) is carried out in June, and the fertilizer is a balanced compound fertilizer, wherein N: P2O5: K2O=15:15:15, 500-600g / plant is applied in shallow furrows; the 4th time (winter flowering fertilizer) is carried out in December, organic fertilizer is selected and high-phosphorus compound fertilizer is applied in appropriate amount, among which N:P2O5:K2O=14:16:15, fertilization is combined with deep plowing to expand the holes and improve the soil, the hole depth is 30-40cm, the hole width is 30-40cm, the hole length is 150-180cm, the amount of fertilizer applied is 20-40kg / plant of organic fertilizer and high-phosphorus compound fertilizer, among which N:P2O5:K2O=14:16:15, 300-400g / plant.

[0051] Example 2

[0052] The method for rapidly expanding the crown of pomelo and achieving early high yield in this embodiment comprises:

[0053] (1) High grafting and seed replacement time

[0054] The best time for grafting is January to February.

[0055] (2) Scion varieties and high grafting methods

[0056] We selected Ruby Green Pomelo branches with full buds as scions, and all of them were grafted with short-branch single-bud grafting. The original varieties were Guanxi Honey Pomelo (scion) / Sour Pomelo (rootstock), and after high grafting, the rootstock was Sour Pomelo, the middle rootstock was Guanxi Honey Pomelo, and the scion was Ruby Green Pomelo.

[0057] (3) Selection of high joints and distribution of high joint locations

[0058] The distribution of high-grafting parts is selected according to the principle of three-dimensional and multi-directional. Based on the three-dimensional heights of the lower, middle and upper parts of the tree and the canopy in different directions of east, west, south, north and center, high-quality native branches with the optimal height and direction are selected (each high-grafting position of the upper, middle and lower canopy is slightly staggered up, down, left and right within each canopy frame as much as possible, and a three-dimensional and full canopy is formed after the branches and shoots sprout, laying the foundation for early high yield) for high-grafting.

[0059] ① For the lower canopy grafting, select 3 to 5 optimal native branches at the 2nd to 3rd level branches of the trunk at different locations (east, west, south, north, and center) at a height of 0.7 to 1.0 m above the ground, cut them flatly at a distance of 5 to 10 cm, select branches with full buds of the Ruby Green Pomelo variety as scions, and use the short branch single bud grafting method for high grafting. The remaining native branches are cut off at the branches.

[0060] ② Middle canopy high grafting: At different locations (east, west, south, north, center) at 1.0 to 1.8 m above the ground, select 8 to 10 optimal native branches at the 3rd to 5th level of the branches, cut them flatly at 5 to 10 cm, select branches with full buds of Ruby Green Pomelo as scions, and use short branch single bud grafting method for high grafting. The rest of the native branches are cut off at the branches.

[0061] ③ For the upper canopy grafting, select 3 to 5 optimal native branches at the 5th to 7th level branches of the trunk at different directions (east, west, south, north, and center) at a height of 1.8 to 2.3 m above the ground, cut them flatly at a distance of 5 to 10 cm from the stump, select branches with full buds of the Ruby Green Pomelo variety as scions, and use the short branch single bud grafting method for high grafting. The remaining native branches are cut off at the branches.

[0062] (4) Post-reception management

[0063] ① Management of original branches (base stock and intermediate stock): About 25 days after high grafting, new buds will continue to sprout from the original branches. They should be removed immediately after sprouting to reduce the nutrient consumption of the tree and promote the rapid germination and growth of the scion.

[0064] ② Management of scion and new shoots: The high-grafted scion begins to germinate about 25 days after grafting. During the growth of new shoots, for new shoots with vigorous growth, pinch off the top in time when they grow to 20-25 cm. Pinching off the top not only promotes the maturation of new shoots, but also increases the output of new shoots at the next level, and so on to cultivate multiple levels of branches. For new shoots with moderate growth, let them grow naturally until they are self-pruned, and they can be used as fruit-bearing branches for the next year.

[0065] ③Remove the grafting film: When the second-level shoots are mature, remove the grafting film in time to prevent the tree from swelling and wrapping the grafting film inside the tree, hindering the transport of nutrients and affecting the growth of the tree.

[0066] ④ Protection of new shoots: Aphids, leafminers, and thrips often occur during the new shoots. Aphid control: When aphids are found on tender shoots, use imidacloprid, acetamiprid, thiamethoxam or avermectin for foliar spraying, spray once every 7 to 10 days, and spray 2 to 3 times continuously; Leafminer control: It often occurs when rain comes from April to May every year. When most tender leaves grow to 0.5 to 2.5 cm, use emamectin benzoate, avermectin, ivermectin, diflubenzuron or diflubenzuron for foliar spraying, spray once every 7 to 10 days, and spray 2 to 3 times continuously; Thrips control: When the new shoots grow to 3 to 5 cm, use imidacloprid, high-efficiency chlorflucythrinate, clothianidin or emamectin benzoate for foliar spraying, spray once every 7 to 10 days, and spray 2 to 3 times continuously.

[0067] (5) Tree water and fertilizer management

[0068] The technical method of the present invention is used to carry out high grafting of Ruby Green Pomelo in January, buds begin to appear in late February to early March of the following year, and the flowering period begins in late March. During this period, water and fertilizer management is as follows.

[0069] Water management: The local area (Ruili, Dehong) has distinct dry and wet seasons. Winter and spring (November to April of the following year) are dry seasons, and summer and autumn (May to October) are rainy seasons. Drip irrigation is carried out once 15 days after high grafting, and then every 10 to 15 days until the rainy season comes and stops drip irrigation; starting from January of the following year, drip irrigation is carried out every 10 to 15 days until the rainy season comes and stops drip irrigation to keep the soil moist and lay the foundation for high yield.

[0070] Fertilization management: grapefruit trees are top-dressed four times a year, and the amount of fertilizer applied to each tree varies slightly according to the size of the tree. The first time (spring shoot fertilizer) is from February to March, and the fertilizer is balanced compound fertilizer (N: P2O5: K2O = 15: 15: 15), and 300-400g / plant is applied in shallow furrows; the second time (late spring shoot fertilizer) is in late May, and the fertilizer is high nitrogen and potassium compound fertilizer (N: P2O5: K2O = 20: 5: 20), and 400-500g / plant is applied in shallow furrows; the third time (strong shoot fertilizer) is in June, and the fertilizer is balanced compound fertilizer (N: P2O5: K2O = 15: 15: 15), Sprinkle 500-600g / plant in shallow furrows; the 4th time (winter flowering fertilizer) is in December. Choose organic fertilizer and apply appropriate amount of high-phosphorus compound fertilizer (N: P2O5: K2O=14:16:15). When applying fertilizer, combine deep plowing to expand the holes and improve the soil. The hole depth is 30-40cm, the hole width is 30-40cm, and the hole length is 150-180cm. The amount of fertilizer applied is 20-40kg / plant of organic fertilizer and 300-400g / plant of high-phosphorus compound fertilizer (N: P2O5: K2O=14:16:15).

[0071] Existing Chinese literature has disclosed the high-position grafting and high-yield cultivation technology of crystal pomelo. [1] Zhang Zhibiao, Tao Xingxing, Li Yue, et al. High-position grafting and high-yield cultivation technology of crystal pomelo [J]. Agricultural Science and Technology Communications, 2022, (09): 232-234. The published article describes that the white flesh honey pomelo is first trimmed flat at a height of 1.2 to 1.5 m from the ground with an electric pruner or saw, leaving 8 to 10 grafted side branches on each tree. The length of the grafted side branches is generally 15 cm. Pay attention to leaving 2 to 3 leading branches when pruning to ensure the supply of nutrients.

[0072] The present invention selects the grafting site in three dimensions (divided into three canopy layers: lower, middle, and upper), and then in multiple directions (east, west, south, north, and center). It does not simply select a height for pruning and grafting. Compared with existing Chinese literature ([1] Zhang Zhibiao, Tao Xingxing, Li Yue, et al. Crystal pomelo high-position grafting and high-yield cultivation technology [J]. Agricultural Science and Technology Communications, 2022, (09): 232-234), the present invention does not need to retain the leading branch (the present invention is grafted in January and February, and the survival rate of grafting without retaining the leading branch is also high). The present invention aims to quickly expand the crown and bear fruit early. The grafting site is selected in three dimensions and multiple directions. The three-dimensionality is to ensure that new shoots can be quickly generated at each height of the crown. The multi-directionality is to consider the uniform distribution of new shoots in the future, so that the branches in a certain direction will not be too dense or too sparse. The three-dimensional and multi-directionality is considered from the perspective of rapid crown expansion and the fullness of the crown after crown expansion. Secondly, different heights can make each height bear fruit, laying the foundation for high yields;

[0073] Secondly, the present invention focuses on the branching number of branches selected at each height, and according to different grafting heights, different branching numbers are also limited. With the increase of height, the more branching numbers are selected, for example, in the middle canopy, the height is 1.0-1.8m above the ground, the 3-5th branch of the branch (the branching number is 3-5, i.e., the shoot is extracted 3-5 times), and the branching number in this range is mostly the fruiting mother branch at this height. The branches grafted at the branches in this range can bear fruit after the branches extracted in the current year are mature. If the branching number restriction of the height is not made, it is possible to graft on the branches 1-2 at the branches at this height, and the first and second new shoots extracted by such branches can only be backbone branches, and it takes a long time to bear fruit. Therefore, according to the technical method of the present invention, the grafting can bloom and bear fruit within one year after grafting, and the yield can reach 50-80kg / per column or more after two years after grafting, while the grafting method in the existing literature can only reach 40-70kg per plant after three years after grafting. Therefore, the restriction on the number of branches at different heights can promote early and high yields, which is an unexpected technical effect. Figure 1-4 The survival rate of the grafting method of the present invention is over 95%.

[0074] In summary, the present invention proposes a variety renewal method for pomelo that can quickly expand the crown and increase early yield. The method adopts the three-dimensional and multi-directional grafting principle and performs grafting on branches of different levels of the trunk. It can not only quickly expand the crown, but also promote early flowering and fruiting, and early production.

[0075] Generate economic benefits earlier: Traditional grapefruit grafting usually takes 3 years to bear fruit, but the grafting technology of this invention can produce flowers and fruits one year later, which is 2 years earlier than the traditional method, and can generate economic benefits earlier.

[0076] Rapid crown expansion: The crown of pomelo is still sparse after two years of high grafting using the traditional high grafting method, but the crown is full and the branches are evenly distributed after one year of high grafting using the technology of the present invention.

[0077] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for rapid canopy expansion and early high yield of grapefruit varieties, characterized in that: The following steps are involved: S1: Choose the time for high grafting, scion variety and rootstock; S2: Selecting high grafting sites to implement three-dimensional multi-directional high grafting, the high grafting sites include the east, west, south, north and middle locations of the three canopy layers of the tree body; S3: After high grafting, post-grafting management and tree water and fertilizer management are carried out, and the post-grafting management includes native branch and trunk management, scion and new shoot management, and removal of the grafting film.

2. The method for rapid canopy expansion and early high yield of grapefruit varieties as claimed in claim 1, characterized in that: The step S1 comprises: The time for high grafting is from January to February; The scion variety is Ruby Green Pomelo; The rootstock types used are sour pomelo as the base rootstock and Guanxi honey pomelo as the intermediate rootstock.

3. The method for rapid canopy expansion and early high yield of grapefruit varieties as claimed in claim 1, characterized in that: The high-joining parts in step S2 include the lower canopy, the middle canopy, and the upper canopy of the tree body; Lower canopy high grafting: The height position is selected at the 2nd-3rd level branches of the main trunk at a height of 0.7 to 1.0 meters, and 3 to 5 branches are retained. Each branch is cut flat to retain a 5 to 10 cm log stake for easy grafting in the later stage; branches with full buds of the Ruby Green Pomelo variety are selected as scions, and short-branch single-bud cutting grafting is used for high grafting; the remaining native branches are cut off at the branches to avoid competition for nutrients; Middle canopy high grafting: The height position is selected at 1.0m to 1.8m, and the branch level is 3-5; Branch selection: Select 8 to 10 healthy side branches, cut flat at 5-10cm, select branches with full buds of Ruby Green Pomelo variety as scion, and use short branch single bud grafting method for high grafting; the rest of the original branches are cut off at the branch; Upper canopy high grafting: The height position is selected between 1.8 meters and 2.3 meters; the number of branches is 5-7 levels; branch selection: retain 3 to 5 high-quality branches, cut flat at 5 to 10 cm, choose branches with full buds of the Ruby Green Pomelo variety as scion, and use short branch single bud grafting method for high grafting; the remaining native branches are cut off at the branches.

4. The method for rapid canopy expansion and early high yield of grapefruit varieties as claimed in claim 1, characterized in that: In the step S2, the high grafting method adopts the short branch single bud grafting method to perform the high grafting of Ruby Green Pomelo.

5. The method for rapid canopy expansion and early high yield of grapefruit varieties as claimed in claim 1, characterized in that: The post-connection management in step S3 specifically includes: Management of native branches: within 25 days after high grafting, check the native buds and new shoots, and promptly remove the sprouted new buds to concentrate nutrients to promote the growth of the scion and avoid competition for nutrients with the native branches; Scion and new shoot management: When the scion grows to 20-25 cm, pinch the top to promote the growth and branching of lower branches, and quickly expand the crown to form a high-yield structure; Removing the grafting film: Observe the growth of new shoots, and remove the grafting film in time after the second-level new shoots mature, so as not to affect the delivery of nutrients and the growth of branches.

6. The method for rapid canopy expansion and early high yield of grapefruit varieties as claimed in claim 1, characterized in that: The tree water and fertilizer management in step S3 specifically includes: Water management: Carry out the first drip irrigation within 15 days after grafting, and then drip irrigation every 10 to 15 days; adjust the irrigation frequency according to climatic conditions to keep the soil moist and the roots grow normally. Fertilization management: Fertilizer should be applied to the soil and mixed with covering soil several times to avoid direct contact of fertilizer with the root system and reduce fertilizer damage.

7. The method for rapid canopy expansion and early high yield of grapefruit varieties as claimed in claim 1, characterized in that: The fertilization management specifically includes: topdressing 4 times a year, the first time is spring shoot promotion fertilizer in February and March, the fertilizer is balanced compound fertilizer, wherein N: P2O5: K2O = 15: 15: 15, 300-400g / plant is applied in shallow furrows; the second time is late spring shoot promotion fertilizer in late May, the fertilizer is high nitrogen and potassium compound fertilizer, wherein N: P2O5: K2O = 20: 5: 20, 400-500g / plant is applied in shallow furrows; the third time is strong shoot fertilizer in June, the fertilizer is balanced compound fertilizer, wherein N: P2O5: K2O = 1 5:15:15, 500-600g / plant in shallow furrows; the fourth time is winter flowering promotion fertilizer in December, choose organic fertilizer and apply appropriate amount of high-phosphorus compound fertilizer, among which N:P2O5:K2O=14:16:15, when fertilizing, combine deep plowing to expand the hole and improve the soil, the hole depth is 30-40cm, the hole width is 30-40cm, the hole length is 150-180cm, the amount of fertilizer applied is 20-40kg / plant of organic fertilizer and high-phosphorus compound fertilizer, among which N:P2O5:K2O=14:16:15, 300-400g / plant.

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