Top grafting method for old litchi trees

Abstract

The invention belongs to the technical field of planting, and particularly relates to a high-position grafting method for an old litchi tree, the method is suitable for being carried out in March to May or September to October every year, and the method specifically comprises the steps of stock treatment, scion treatment, grafting operation and management after grafting, the old litchi tree with the tree age of 10-30 years is selected as the stock, a semi-lignified current-year branch is selected as the scion, and the scion is selected as a semi-lignified current-year branch; a high-position grafting method is adopted for grafting, based on the toughness of semi-lignified current-year branches and control over the scion length, it is ensured that scions and stocks are tightly combined, the risk of fracture caused by external force is reduced, healing of the scions and the stocks is effectively promoted in the mode of section trimming, disinfection treatment and EM bacterial liquid spraying, and it is verified that the scions and the stocks are not prone to fracture. The grafting survival rate reaches 92% or above, fruits can be borne in 2-3 years, high yield can be recovered in 3-4 years, the average plant yield reaches 30 kg or above, and the economic life of old trees can be effectively prolonged.

Description

Technical Field

[0001] This invention belongs to the field of planting technology, specifically relating to a method for high-position grafting of old litchi trees. Background Technology

[0002] Lychee is an important subtropical fruit in my country. Over the long term, many orchards have faced problems such as aging trees, varietal degeneration, poor fruit quality, and low yields. The traditional solution is often to cut down old trees and replant with new seedlings. This method is not only time-consuming, generally requiring 5-8 years to reach full production, but also involves high initial costs. While high-position grafting technology is used in fruit trees, there is a lack of systematic optimization plans for grafting procedures and post-grafting management on old lychee trees. This results in low grafting survival rates, slow new shoot growth, and new shoots being easily broken under gravity and external forces, leading to minimal yield increases in the later stages. This fails to meet the needs of fruit growers for rapid improvement of old trees and increased economic benefits. Summary of the Invention

[0003] To achieve rapid improvement of old trees and increase grafting survival rate, this invention provides a high-position grafting method for old litchi trees. This method can restore high yield in 3-4 years and has the advantages of high survival rate and good economic benefits.

[0004] To achieve the above-mentioned objectives, the following technical solution is provided:

[0005] Provides methods for high grafting of old lychee trees, including:

[0006] Step 1: Choose to graft during March to May or September to October each year, when there are 3 to 5 consecutive sunny days and the temperature is between 20℃ and 28℃.

[0007] Select old litchi trees aged 10 to 30 years with no diseases, pests, or mechanical damage to the trunk and main branches, and with well-developed root systems and moderate vigor as rootstocks. Retain one upright central branch of the rootstock and make oblique cuts on the other main branches to form a cut, keeping the main branches 1.5m to 2m high. Make 1 to 2 openings at the high point of the cut, with the openings being 2cm to 3cm long and reaching the xylem.

[0008] Select healthy, disease-free, and semi-lignified branches of high-quality litchi varieties from the current year as scions. The length of the scion is 5cm to 8cm. The scion retains 2 to 3 plump buds. The lower end of the scion is the insertion end that is inserted into the opening. The insertion end is cut and beveled to form a wedge shape.

[0009] Step 2: Insert one scion into the opening of the rootstock, so that the bevel of the scion is in contact with the inner side of the opening of the rootstock, and the bevel of the scion protrudes 0.1cm to 0.2cm from the opening. Spray EM bacterial solution at the grafting point. First, wrap the cut end of the rootstock with aluminum foil, then wrap the interface between the rootstock and the scion with plastic film strips, and then wrap the scion with plastic film strips.

[0010] Step 3: Regular water and fertilizer management, branch management, and pest and disease management after grafting.

[0011] In some implementations, the litchi varieties used for grafting include one or more of Guiwei, Nuomici, Xianjinfeng, and Bingli.

[0012] In some implementations, the knives used for cutting openings and bevels are disinfected with disinfectant before use.

[0013] In some implementations, in step one, a cutting tool is used to smooth the cut, the opening, and the bevel.

[0014] In some embodiments, the water and fertilizer management includes the following:

[0015] 10 to 15 days after grafting, apply 1 ml of amino acid water-soluble fertilizer to each plant in 1 L of water and apply 0.5 kg of the first compound fertilizer to each plant in 25 kg of water. The nitrogen, phosphorus and potassium content of the first compound fertilizer is 17%.

[0016] After that, apply 0.5 kg of the second compound fertilizer per plant per month, diluted with 20 kg of water. The nitrogen, phosphorus and potassium contents of the second compound fertilizer are 26%, 8% and 16%, respectively.

[0017] In some implementations, the branch management includes the following steps:

[0018] 15-20 days after grafting, remove any new buds and suckers that sprout on the rootstock. Repeat this process every 7-10 days for 2-3 months.

[0019] When the new shoots of the scion grow to 15-20cm, remove the plastic film strips and aluminum foil wrapping, and apply a healing agent to the cut surface of the rootstock after it has dried.

[0020] When the new shoots of the scion grow to 30cm-40cm, pinching should be performed;

[0021] In winter, prune the new shoots of the scion to remove overly dense branches, vigorous shoots, and diseased or pest-infested branches.

[0022] In some implementations, the pest and disease management includes the following steps: regularly inspecting the tree and, when pests and diseases are found, using appropriate pesticides for prevention and control.

[0023] In some embodiments, when controlling the litchi stink bug, the drug is a spray of 800-1000 times diluted 90% trichlorfon crystals;

[0024] When controlling downy mildew, the drug is a 25% metalaxyl wettable powder solution diluted 800-1000 times for spraying.

[0025] The beneficial effects of the high-position grafting method for old litchi trees of the present invention are as follows:

[0026] The high-position grafting method for old litchi trees of this invention shortens the variety improvement cycle: Compared with the traditional method of cutting down and replanting, this invention enables old litchi trees to bear fruit in 2-3 years through high-position grafting, which greatly shortens the time for variety improvement and production and reduces the economic losses of fruit farmers.

[0027] The present invention provides a high-position grafting method for old litchi trees to improve the grafting survival rate. By strictly selecting old trees and scions, choosing appropriate grafting time and scientific grafting operation procedures, and implementing comprehensive post-grafting management measures, the grafting survival rate can be increased to over 90%.

[0028] The high-position grafting method for old litchi trees of this invention reduces the breakage rate of scions. It solves the problem of scions being easily broken under the action of gravity and external forces (wind) by using a saw-cut grafting method on the rootstock.

[0029] The high-position grafting method of this invention for old litchi trees improves fruit yield and quality. The improved litchi trees enter the high-yield period in the 3rd to 4th year after grafting, with a yield increase of 50% to 80% compared to old trees. The fruits are also more uniform in size, have higher sugar content, better taste, and significantly improved commercial value.

[0030] The high-position grafting method for old litchi trees of this invention reduces production costs. It eliminates the need to purchase a large number of seedlings and reclaim land, and utilizes the original root system of the old trees, thus reducing the input of manpower, material resources and financial resources, resulting in significant economic benefits. Detailed Implementation

[0031] For ease of understanding, the present invention will be further described below with reference to preferred embodiments, but this should not be regarded as a limitation of the present invention.

[0032] Example 1

[0033] The method for high-position grafting of old litchi trees disclosed in this invention includes the following steps:

[0034] Grafting time and weather: October 24, 2022 to October 26, 2022, sunny weather, temperature 20℃~31℃. During this period, the sap flow is vigorous, which is conducive to the formation of callus tissue in scions and rootstocks.

[0035] Rootstock preparation: In the litchi orchard of the Sihui Branch of Guangdong State Farms Tropical Agriculture Research Institute Co., Ltd., 20 15-year-old litchi trees with no diseases, pests, or mechanical damage to the trunk and main branches, and with well-developed root systems and moderate vigor were selected as rootstocks. The litchi trees included any one of the following varieties: Guiwei, Nuomici, Xianjinfeng, and Bingli, and other litchi varieties could also be used. One upright central branch was retained on the rootstock, and the main branch was kept at a height of 1.5m to 2m. The cut was trimmed with a knife to make the cut surface smooth. Two incisions were made at the high point of the cut, and the cut surfaces of the incisions were smoothed. The length of the incisions was 3cm and the depth reached the xylem.

[0036] Using 10-30 year old litchi trees as grafting rootstock is more advantageous. Litchi trees that are too young may not have reached their peak fruiting period, while those that are too old are severely aged. Even if grafting is successful, the yield will be limited in the later stages. On the other hand, litchi trees aged 10-30 years have well-developed root systems that are not severely aged, and their xylem and phloem transport systems are relatively unobstructed. They have a strong ability to absorb water and nutrients, which can provide basic support for the growth of new branches after grafting. In addition, they have moderate stress resistance, and the wounds heal faster after grafting, resulting in stronger sprouting and growth of new branches.

[0037] Retaining a central upright branch that draws water can accelerate the transport of water from the roots to the grafting site, improving the grafting survival rate. It also allows the main branches to maintain a height of 1.5m to 2m, creating a drop that prevents the scion and new shoots from crowding each other's growth space after they have taken shape, resulting in a better canopy structure. Smoothing the cut and opening surfaces helps the scion and rootstock fit together tightly, accelerates the formation of callus tissue at the grafting site, and also helps to prevent water accumulation to some extent.

[0038] Scion preparation: Select healthy, disease-free, and semi-lignified current-year Guiwei lychee branches as scions. The scion should be 6cm long and have 2-3 plump buds. The lower end of the scion is the insertion end. Make a bevel on both sides of the insertion end of the scion to form a cut surface. The vertical length of the cut surface should be 3cm. The cut surface should be smoothed so that the lower end of the scion is wedge-shaped.

[0039] Semi-lignified, high-quality lychee cultivars from the current year have plump buds, ensuring a high bud break rate. Retaining 2-3 buds not only guarantees the bud break rate but also prevents too many new buds from competing for nutrients, which can lead to weak new branches. The cambium cells of semi-lignified, current-year branches undergo vigorous cell division, resulting in rapid callus formation after grafting, which accelerates graft healing and improves the survival rate. The scion has well-developed vascular tissue, which can efficiently transport nutrients and support rapid development of new branches. The pre-formed cuticle can reduce water evaporation and lower the risk of wilting. Furthermore, the current-year Guiwei lychee branches have moderate hardness and toughness, making them easy to cut but not easy to break, effectively reducing the risk of breakage after grafting and further improving the survival rate of grafts.

[0040] A scion 5cm to 8cm in length ensures sufficient cortical, xylem, and pith tissues; these tissues are the main physiological structures involved in grafting. Simultaneously, a 5cm to 8cm long scion can store nutrients, including carbohydrates and amino acids, for callus formation and new bud sprouting after grafting. If the scion is too long, it increases the risk of breakage from external forces.

[0041] A smooth cut surface allows the scion and rootstock to fit more closely, reducing gaps, increasing the contact area of ​​the cambium, accelerating callus formation, and allowing the vascular tissue to connect more smoothly, ensuring the transport of water and nutrients.

[0042] Grafting procedure: Insert one scion into the opening of each rootstock, ensuring the cut surface of the scion fits tightly against the opening of the rootstock. Leave 0.2cm of the cut surface of the scion protruding from the opening to allow space for callus growth at the grafting site. Spray the grafting site with EM bacterial solution to promote wound healing and enhance immunity. After inserting the scion, first wrap the grafting site with aluminum foil, then wrap it a second time with plastic film strips to make the scion and rootstock bond more firmly and to isolate pathogens and / or rainwater. Finally, completely cover the scion with plastic film strips to prevent excessive evaporation of moisture from the scion and rainwater intrusion that could lead to rot.

[0043] Post-grafting management: including

[0044] Water and fertilizer management:

[0045] On the 18th day after grafting, begin to remove any sprouts and suckers on the rootstock to reduce nutrient consumption. This should be done every 8 days for 3 months.

[0046] When the new shoots of the scion reach 18cm in length, remove all plastic film strips and aluminum foil to avoid damaging the new shoots and affecting the smooth flow of water and nutrients. After the cut of the rootstock dries, apply a healing agent to promote the healing of the cut and prevent the rootstock from rotting due to lack of healing, which could lead to grafting failure.

[0047] On the 12th day after grafting, apply amino acid water-soluble fertilizer and compound fertilizer. For the amino acid water-soluble fertilizer, use 1 ml of amino acid water-soluble fertilizer per plant, diluted in 1 L of water, and apply it. For the compound fertilizer, use 0.5 kg of compound fertilizer per plant, diluted in 25 kg of water, and apply it. After that, apply 0.5 kg of high-nitrogen compound fertilizer per plant, diluted in 20 kg of water, once a month.

[0048] Branch management:

[0049] When the new shoots of the scion grow to 30cm-40cm, pinch them back to promote the growth of lateral buds and increase the area exposed to sunlight. In winter, prune the new shoots to remove overly dense branches, vigorous branches, and diseased or pest-infested branches to cultivate a good canopy structure.

[0050] Pest and disease management:

[0051] Regularly inspect the trees. When pests or diseases are found, use highly effective, low-toxicity, and low-residue pesticides for spraying. For example, if litchi stink bugs are found, spray with an 800-1000 times diluted solution of 90% trichlorfon crystals. If downy mildew is found, spray with an 800-1000 times diluted solution of 25% metalaxyl wettable powder.

[0052] In Example 1 above, the tools used must be disinfected with 75% alcohol before each sawing, opening, and cutting to prevent the tools from carrying pathogens that could invade the rootstock and scion, leading to grafting failure.

[0053] The grafting survival rate was calculated in the 6th month after grafting, and the results were also calculated in the 2nd and 3rd years after grafting.

[0054] The grafting method described above is performed from March to May or September to October each year, when the temperature is suitable and the trees are growing vigorously, which is conducive to grafting survival. The rootstock is selected from 10-30 year old litchi trees, and the scion is selected from semi-lignified current-year branches. A high-position grafting method is used. Based on the toughness of the semi-lignified current-year branches and the control of the scion length, a tight bond between the scion and rootstock is ensured, reducing the risk of breakage due to external forces. Furthermore, the healing between the scion and rootstock is effectively promoted through cut surface trimming, disinfection, and spraying with EM (Effective Microorganisms) solution, resulting in a grafting survival rate of over 92%. This method can significantly shorten the time for variety improvement and production, extend the economic lifespan of old litchi trees, and reduce economic losses for fruit growers. Verification has shown that the grafting method of this invention enables old litchi trees to bear fruit in 2-3 years, enter the high-yield period in 3-4 years, with an average yield of over 30 kg per tree. The fruits are uniform in size, high in sugar content, and have a good taste, significantly increasing their commercial value.

[0055] Example 2

[0056] This embodiment discloses a method for high-position grafting of old litchi trees, which discloses...

[0057] Grafting time and weather: March 19, 2023 to March 21, 2023, cloudy, temperature 20℃~28℃.

[0058] Rootstock preparation: In the litchi orchard of Dongxing Village, Baishi Town, Yun'an District, Yunfu City, Guangdong Province, 30 old black-leaf litchi trees with a 20-year age, free from diseases, pests, and mechanical damage to the main trunk and branches, and with well-developed root systems and moderate vigor were selected as rootstocks. One upright water-draining branch in the middle of the rootstock was retained, and the other main branches were cut off obliquely at a length of 1.5m to 2m and the cut was trimmed with a knife to make the cut surface smooth. Two cuts were made at the high point of the cut, and the cut surfaces of the cuts were trimmed smooth. The length of the cuts was 3cm and the depth reached the xylem.

[0059] Scion preparation: Select healthy, disease-free, semi-lignified branches of the current year's Yuezhou Red Lychee as scions. The length of the scion should be 6cm, and 2-3 plump buds should be retained on the scion. Make cuts on both sides of the lower end of the scion, with a cut length of 3cm. The cut surface should be smoothed so that the lower end of the scion is wedge-shaped.

[0060] The remaining grafting operations and post-grafting management are the same as in Example 1.

[0061] The grafting survival rate was calculated in the 6th month after grafting, and the results were also calculated in the 2nd and 3rd years after grafting.

[0062] Table 1 is a statistical table of the old litchi trees after grafting in Examples 1 and 2. It can be seen that the grafting method is applicable to the grafting of multiple litchi varieties, and the grafting survival rate is over 92%. The trees can bear fruit in the second year after grafting and achieve high yield in the third year after grafting, with an average yield of over 30 kg per tree.

[0063] Table 1. Statistics on Grafting of Old Litchi Trees

[0064]

[0065] The above embodiments are preferred embodiments of the present invention. In addition, the present invention can be implemented in other ways. Any obvious simple substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for high-position grafting of old litchi trees, characterized in that, include: Step 1: Choose to graft during March to May or September to October each year, when there are 3 to 5 consecutive sunny days and the temperature is between 20℃ and 28℃. Select old litchi trees aged 10 to 30 years with no diseases, pests, or mechanical damage to the trunk and main branches, and with well-developed root systems and moderate vigor as rootstocks. Retain one upright central branch of the rootstock and make oblique cuts on the other main branches to form a cut, keeping the main branches 1.5m to 2m high. Make 1 to 2 openings at the high point of the cut, with the openings being 2cm to 3cm long and reaching the xylem. Select healthy, disease-free, and semi-lignified branches of high-quality litchi varieties from the current year as scions. The length of the scion is 5cm to 8cm. The scion retains 2 to 3 plump buds. The lower end of the scion is the insertion end that is inserted into the opening. The insertion end is cut and beveled to form a wedge shape. Step 2: Insert one scion into the opening of the rootstock, so that the bevel of the scion is in contact with the inner side of the opening of the rootstock, and the bevel of the scion protrudes 0.1cm to 0.2cm from the opening. Spray EM bacterial solution at the grafting point. First, wrap the cut end of the rootstock with aluminum foil, then wrap the interface between the rootstock and the scion with plastic film strips, and then wrap the scion with plastic film strips. Step 3: Regular water and fertilizer management, branch management, and pest and disease management after grafting.

2. The grafting method according to claim 1, characterized in that, The lychee varieties used for grafting include one or more of Guiwei, Nuomici, Xianjinfeng, and Bingli.

3. The grafting method according to claim 1, characterized in that, Knives used for cutting openings and bevels must be disinfected with disinfectant before use.

4. The grafting method according to claim 1, characterized in that, In step one, a cutting tool is used to smooth the cut, the opening, and the bevel.

5. The grafting method according to claim 1, characterized in that, The water and fertilizer management includes the following: 10 to 15 days after grafting, apply 1 ml of amino acid water-soluble fertilizer to each plant in 1 L of water and apply 0.5 kg of the first compound fertilizer to each plant in 25 kg of water. The nitrogen, phosphorus and potassium content of the first compound fertilizer is 17%. After that, apply 0.5 kg of the second compound fertilizer per plant per month, diluted with 20 kg of water. The nitrogen, phosphorus and potassium contents of the second compound fertilizer are 26%, 8% and 16%, respectively.

6. The grafting method according to claim 1, characterized in that, The branch management includes the following steps: 15-20 days after grafting, remove any new buds and suckers that sprout on the rootstock. Repeat this process every 7-10 days for 2-3 months. When the new shoots of the scion grow to 15-20cm, remove the plastic film strips and aluminum foil wrapping, and apply a healing agent to the cut surface of the rootstock after it has dried. When the new shoots of the scion grow to 30cm-40cm, pinching should be performed; In winter, prune the new shoots of the scion to remove overly dense branches, vigorous shoots, and diseased or pest-infested branches.

7. The grafting method according to claim 1, characterized in that, The pest and disease management includes the following steps: regularly inspect the tree, and when pests and diseases are found, select appropriate pesticides for prevention and control.

8. The grafting method according to claim 7, characterized in that, When controlling the litchi stink bug, the drug is a spray of 800-1000 times diluted 90% trichlorfon crystal solution; When controlling downy mildew, the drug is a 25% metalaxyl wettable powder solution diluted 800-1000 times for spraying.

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