A grafting propagation method of mallotus repandus

Abstract

The application discloses a grafting propagation method of Murraya paniculata, belongs to the technical field of Murraya paniculata propagation, and grafts Murraya paniculata through the steps of preparation of scions and stock plants, grafting and post-grafting management, and simultaneously, a modified gel sheet is prepared; before callus formation, the modified gel sheet can effectively sterilize, treat incision exudate, reduce oxidation, make the thickness of brown septa thin, and cooperate with other steps, so that the survival rate of Murraya paniculata grafting is improved, and the needs of Murraya paniculata clone large-scale breeding can be met.

Description

Technical Field

[0001] This invention relates to the field of propagation technology of Litsea cubeba, and in particular to a grafting propagation method for Litsea cubeba. Background Technology

[0002] Litseamollis Hemsl., commonly known as mountain pepper, mountain ginger, or large litsea, belongs to the genus Litsea in the family Lauraceae. It is an important ecological conservation tree species and a biomass energy tree species. Litseamollis oil can be extracted from its flowers, leaves, and fruits. Its main component, citral, is a key raw material for formulating fragrances, flavorings, and synthesizing vitamins A and E. Its fruit kernels contain approximately 40% fatty oil, which can be used as aircraft lubricant or as a raw material for soap making. Litseamollis oil also has antifungal and antiviral properties. The roots and fruits of Litseamollis are used medicinally, possessing properties that regulate qi and strengthen the spleen, relieve exterior symptoms and dry dampness. It can treat indigestion, wind-cold-dampness pain, traumatic swelling and pain, postpartum edema and diarrhea due to cold, abdominal distension, and heatstroke-related pain.

[0003] Due to the wide range of applications of Litsea cubeba, market demand for Litsea cubeba resources has surged, leading to a rapid and sharp decline in wild resources due to rampant and unregulated harvesting. Litsea cubeba is highly adaptable and suitable for cultivation in all provinces along the Yangtze River. However, the development of plantations in various regions is constrained by artificial propagation techniques, with most relying on the collection of wild seedlings. These wild seedlings are of varying quality, have low survival rates, low yields, and poor resistance, making them unsuitable for large-scale development.

[0004] Currently, Litsea cubeba is mainly propagated through seedling cultivation. However, seedlings often exhibit phenotypic segregation, making it difficult to maintain desirable traits in hybrid offspring. Furthermore, as Litsea cubeba is dioecious, it is impossible to rapidly distinguish male and female seedlings on a large scale. Plant tissue culture technology offers advantages such as high propagation coefficient, rapid propagation speed, and easy maintenance of desirable traits in the parent plant, making it suitable for Litsea cubeba propagation. However, existing research indicates that Litsea cubeba tissue culture suffers from unstable callus induction efficiency, low redifferentiation and rooting efficiency, and a lack of transplanting trials of regenerated plants. Therefore, it cannot yet be applied to industrialized seedling production, and the tissue culture method for Litsea cubeba propagation is difficult to commercialize. Moreover, due to the influence of metabolites such as citral, the wounds on Litsea cubeba branches are easily oxidized, making it difficult for callus tissue to form. This results in insufficient affinity between the scion and the rootstock. After the grafted branches survive, once the binding plastic tape is removed, they start to turn black, rot, and dry out from the cut end, eventually leading to the death of the scion. This results in a low grafting survival rate for Litsea cubeba.

[0005] Based on this, the present invention improves the grafting propagation method of Litsea cubeba, thereby increasing the grafting survival rate of Litsea cubeba to meet the needs of large-scale breeding. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a grafting propagation method for Litsea cubeba, which reduces oxidation of grafting wounds, promotes callus formation, and improves the grafting survival rate of Litsea cubeba.

[0007] The present invention solves the above-mentioned technical problems through the following technical means:

[0008] A grafting propagation method for Litsea cubeba includes the following steps:

[0009] S1. Preparation of scions: From the winter of the previous year (around December, after the leaves have fallen) to the spring of the following year (around March, before the leaf buds sprout), since Litsea cubeba flowers before its leaves appear, experiments have shown that scions collected after the flower buds sprout do not affect the grafting survival rate, thus extending the scion collection time. Select healthy, one-year-old, semi-lignified branches with plump buds, a diameter of 0.4-0.8cm, and free from diseases and pests from the outer periphery of mature Litsea cubeba mother trees, especially the upper outer branches. Cut the branches to a length of 50-60cm, tie them into bundles, seal them in plastic film, and store them in a low-temperature cold storage at 0-4℃ as scions. Take them out before grafting.

[0010] S2. Preparation of rootstock: Select the stems of healthy Litsea cubeba seedlings that are 1-2 years old and have a ground diameter of 0.4-0.8cm and cut them to obtain the rootstock;

[0011] S3. Grafting: Take out the scion and cut it. Place the modified gel sheet on the cut surface. Soak the scion in a 5% sodium chloride solution for 3-5 minutes. After taking it out and air drying, insert it into the rootstock cut. Then tie the grafting point tightly with the prepared plastic film strip.

[0012] When inserting the scion into the rootstock cut, the cut surface of the rootstock should be in contact with the large bevel of the scion, and the lower end should be firmly inserted. The rootstock and scion should be tightly attached to both sides of the modified gel sheet, so that they are closely connected in all directions. If the cut surfaces of the scion and rootstock are not the same, causing the cambium layers on both sides to be misaligned, at least one side should be aligned.

[0013] S4. Post-grafting management: After grafting, water to keep the soil moist, and carry out water and fertilizer management and pest and disease control.

[0014] Preferably, the rootstock should be kept moist after grafting. To prevent rootstock suckers from competing with the new shoots of the scion for nutrients, the tender shoots emerging from the rootstock need to be removed in a timely manner, generally 4-5 times. When the new shoots of the scion grow to about 30cm, the film strip binding the graft union should be removed in time. At the same time, a support should be inserted next to the grafted seedling to fix the seedling in place to prevent the newly emerging shoots from being broken by the wind.

[0015] Furthermore, the specific processing steps of the rootstock in step S2 are as follows: cut the rootstock stem 4-6cm from the ground, make a vertical downward cut on one side of the cut, so that the width of the cut is the same as the width of the large bevel of the scion, and then make a 0.8-1.2cm oblique cut from the outside to the inside at 2.5-3.5cm from the ground, and remove the upper part of the bark with the wood to expose the cut surface.

[0016] Furthermore, the specific cutting process of the scion in step S3 is as follows: take out the scion and seal it with wax. When cutting, leave 1-2 plump buds at the top, cut a large bevel 2.5-3.5cm long at the bottom, and then cut a small bevel 0.8-1.2cm long on the back.

[0017] Furthermore, in step S3, when the scion is cut, the cut surface should be symmetrical, flat and smooth on both sides. The large bevel of the scion should be 0.4-0.6 cm longer than the cut depth of the rootstock, so that the upper part of the large bevel of the scion protrudes 0.4-0.6 cm from the cut surface of the rootstock. This is called "exposing the white part", which is conducive to the connection of the callus tissue between the scion and the rootstock and the firm healing.

[0018] Furthermore, the modified gel sheet in step S3 comprises the following raw materials:

[0019] 10-100 parts by weight of hyaluronic acid, 10-100 parts by weight of sodium alginate, 0.1-3 parts by weight of methyl 4-hydroxy-3-methoxycinnamate, 1-9 parts by weight of dipentaerythritol, 1-20 parts by weight of nano silica powder, 1-8 parts by weight of calcium chloride, and 0.2-2 parts by weight of polyacrylamide.

[0020] Furthermore, the modified gel sheet in step S3 comprises the following raw materials:

[0021] 20-40 parts by weight of hyaluronic acid, 20-40 parts by weight of sodium alginate, 0.2-1 parts by weight of methyl 4-hydroxy-3-methoxycinnamate, 3-7 parts by weight of dipentaerythritol, 5-10 parts by weight of nano silica powder, 2-6 parts by weight of calcium chloride, and 0.5-1 parts by weight of polyacrylamide.

[0022] Furthermore, the modified gel sheet is prepared as follows:

[0023] (1) Weigh calcium chloride to prepare a calcium chloride solution with a mass fraction of 4%; add nano silica powder and polyacrylamide together to water, stir and disperse at a rate of 200-300 r / min to prepare a dispersion.

[0024] (2) Weigh out sodium alginate and hyaluronic acid, dissolve them in water and mix them. Then add methyl 4-hydroxy-3-methoxycinnamate and calcium chloride solution and stir. Then add the dispersion to adjust the pH and stir at high speed. Finally, add dipentaerythritol and stir for 20-40 minutes. Sonicate for 10-20 minutes and pour into a silicone mold to solidify to obtain modified gel sheet.

[0025] Furthermore, in the preparation of the modified gel sheet, the pH adjustment operation in step (2) is as follows: the pH is adjusted to 6.8-7.3 using 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer.

[0026] When grafting Litsea cubeba, mechanical damage at the cut site causes cell death and cell sap to flow out. Cells at the cut site readily proliferate in the moist environment, promoting rapid wound healing. However, the outflow of cell sap leaves behind dead cell remnants such as cell walls and protoplasm. Secretions from living cells, such as mucilage and other polysaccharides, also remain at the wound site. In the early stages of grafting, before callus formation, these substances accumulate at the grafting cut of both the scion and rootstock, forming a thick protective layer. A thin film is then used to wrap this layer. Excessive humidity can easily lead to bacterial growth, so it's crucial to ensure proper healing of the graft union while avoiding excessive humidity. The modified gel sheet prepared in this invention is placed at the graft union. Dipentaerythritol is added to modify sodium alginate and hyaluronic acid. Dipentaerythritol forms hydrogen bonds between sodium alginate and hyaluronic acid molecules, thereby enhancing their stability. The gel sheet is then placed at the graft union and subsequently wrapped with a film. As the wound fluid seeps out, the gel sheet slowly absorbs water, reducing humidity while preventing bacteria from entering and mitigating oxidation. Meanwhile, the use of nano-silica powder in the gel sheet can cause an increase in the local pH and osmotic pressure, resulting in a good bactericidal effect. Under the action of polyacrylamide, it is loaded onto sodium alginate and hyaluronic acid. The added methyl 4-hydroxy-3-methoxycinnamate can not only improve the resistance of Litsea cubeba cells, resist bacterial invasion, and accelerate the formation of callus tissue, but also make nano-silica easier to disperse in the molecular chain. During the preparation process, methyl 4-hydroxy-3-methoxycinnamate is covalently combined with sodium alginate and hyaluronic acid, so that methyl 4-hydroxy-3-methoxycinnamate can play a stable role.

[0027] Meanwhile, the addition of the aforementioned nano-silica can effectively improve the tensile strength and toughness of the molecular chains. When the modified gel sheet absorbs the liquid seeping from the cut, it reduces the thickness of the isolation layer. This allows the increased mechanical pressure as the callus cells divide and proliferate to cause the moist and thin isolation layer to rupture and disappear, enabling direct contact between the callus tissue and the rootstock, thereby improving the grafting success rate.

[0028] Beneficial effects:

[0029] (1) The modified gel sheet prepared by the present invention can reduce the amount of oxidized substances formed during the grafting process of Litsea cubeba, inhibit bacterial reproduction, and promote the formation of callus tissue. In this process, since the raw materials are all absorbable substances, they gradually disappear as the isolation layer disappears, which promotes the formation of a common cambium layer between the scion and the rootstock.

[0030] (2) Through the grafting propagation method of the present invention, the grafting survival rate of Litsea cubeba reaches 72%, and the grafting survival rate of Litsea cubeba is effectively improved, which can meet the needs of large-scale propagation.

[0031] Instruction manual illustrations

[0032] Figure 1 Growth of experimental group 1 55 days after grafting. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the embodiments and accompanying drawings:

[0034] This invention provides a grafting propagation method for Litsea cubeba, but a modified gel sheet needs to be prepared before grafting. The specific method for preparing the modified gel sheet of this invention is as follows:

[0035] Example 1: Preparation of modified gel sheets

[0036] (1) Weigh 40g of calcium chloride to prepare a calcium chloride solution with a mass fraction of 4%; add 70g of nano silica powder and 8g of polyacrylamide to 234g of water, stir and disperse at a rate of 250r / min to prepare a dispersion.

[0037] (2) Weigh 300g sodium alginate and 300g hyaluronic acid and dissolve them in 6kg of water and mix them. Then add 6g methyl 4-hydroxy-3-methoxycinnamate and calcium chloride solution and stir. Then add dispersion and adjust the pH to 7.0 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer. Stir at 1500r / min. Finally, add 50g dipentaerythritol and stir for 30min. Sonicate at 600W for 15min and pour into a silicone mold to solidify, and obtain a modified gel sheet with a thickness of 1mm.

[0038] Example 2: Preparation of Modified Gel Sheets

[0039] (1) Weigh 20g of calcium chloride to prepare a calcium chloride solution with a mass fraction of 4%; add 50g of nano silica powder and 5g of polyacrylamide to 165g of water, stir and disperse at a rate of 200r / min to prepare a dispersion.

[0040] (2) Weigh 200g sodium alginate and 200g hyaluronic acid and dissolve them in 4kg of water and mix them. Then add 2g methyl 4-hydroxy-3-methoxycinnamate and calcium chloride solution and stir. Then add dispersion and adjust the pH to 6.8 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer. Stir at a high speed of 2000r / min. Finally, add 30g pentaerythritol and stir for 20min. Sonicate at 700W for 10min and pour into a silicone mold to solidify, and obtain a modified gel sheet with a thickness of 1mm.

[0041] Example 3: Preparation of Modified Gel Sheets

[0042] (1) Weigh 60g of calcium chloride to prepare a calcium chloride solution with a mass fraction of 4%; add 100g of nano silica powder and 10g of polyacrylamide to 330g of water, and stir and disperse at a rate of 300r / min to prepare a dispersion.

[0043] (2) Weigh 400g sodium alginate and 400g hyaluronic acid and dissolve them in 8kg of water and mix them. Then add 5g methyl 4-hydroxy-3-methoxycinnamate and calcium chloride solution and stir. Then add dispersion and adjust the pH to 7.3 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer. Stir at 1200r / min. Finally, add 70g dipentaerythritol and stir for 40min. Sonicate at 600W for 20min. Pour into a silicone mold and solidify to obtain a modified gel sheet with a thickness of 1mm.

[0044] Comparative Example 1: Preparation of Modified Gel Sheets

[0045] The difference between this comparative example and Example 1 is that Comparative Example 1 lacked calcium chloride solution in its preparation process; the remaining steps and raw materials were the same. The preparation process is as follows:

[0046] (1) Add 70g of nano silica powder and 8g of polyacrylamide to 234g of water and stir at a rate of 250r / min to prepare a dispersion.

[0047] (2) Weigh 300g of sodium alginate and 300g of hyaluronic acid, dissolve them in 6kg of water and mix them. Then add 6g of methyl 4-hydroxy-3-methoxycinnamate and stir. Then add the dispersion and adjust the pH to 7.0 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer. Stir at a high speed of 1500r / min. Finally, add 50g of dipentaerythritol and stir for 30min. Sonicate at 600W for 15min to obtain a gel-like substance.

[0048] Comparative Example 2: Preparation of Modified Gel Sheets

[0049] The difference between this comparative example and Example 1 is that the raw materials used in Comparative Example 2 lack calcium chloride and hyaluronic acid. The remaining steps and raw materials are the same. The preparation process is as follows:

[0050] (1) Add 70g of nano silica powder and 8g of polyacrylamide to 234g of water and stir at a rate of 250r / min to prepare a dispersion.

[0051] (2) Weigh 300g of sodium alginate and dissolve it in 300g of water. Add 6g of methyl 4-hydroxy-3-methoxycinnamate and stir. Then add the dispersion and adjust the pH to 7.0 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer. Stir at a high speed of 1500r / min. Finally, add 50g of dipentaerythritol and stir for 30min. Sonicate at 600W for 15min to obtain a gel-like substance.

[0052] Comparative Example 3: Preparation of Modified Gel Sheets

[0053] The difference between this comparative example and Example 1 is that the raw material used in step (2) of Comparative Example 3 lacks methyl 4-hydroxy-3-methoxycinnamate. The remaining steps and raw materials are the same. The preparation process of step (2) is as follows:

[0054] (1) Same as step (1) in Example 1;

[0055] (2) Weigh 300g sodium alginate and 300g hyaluronic acid, dissolve them in 6kg of water and mix them. Then add calcium chloride solution and stir. Then add dispersion and adjust the pH to 7.0 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer. Stir at 1500r / min. Finally, add 50g dipentaerythritol and stir for 30min. Sonicate at 600W for 15min. Pour into a silicone mold and solidify to obtain a modified gel sheet with a thickness of 1mm.

[0056] Comparative Example 4: Preparation of Modified Gel Sheets

[0057] The difference between this comparative example and Example 1 is that Comparative Example 4 did not prepare a dispersion; the remaining steps and raw materials were the same. The preparation process is as follows:

[0058] (1) Weigh 40g of calcium chloride to prepare a calcium chloride solution with a mass fraction of 4%;

[0059] (2) Weigh 300g sodium alginate and 300g hyaluronic acid and dissolve them in 6kg of water and mix them. Then add 6g methyl 4-hydroxy-3-methoxycinnamate and calcium chloride solution and stir. Then add 200g distilled water and adjust the pH to 7.0 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer. Stir at a high speed of 1500r / min. Finally, add 50g dipentaerythritol and stir for 30min. Sonicate at 600W for 15min. Pour into a silicone mold and solidify to obtain a modified gel sheet with a thickness of 1mm.

[0060] Example 4: Grafting propagation of Litsea cubeba

[0061] S1. Preparation of scions: In March, when the leaf buds sprout, select healthy, one-year-old, semi-lignified branches with plump buds, a diameter of 0.6cm, and free from diseases and pests from the outer periphery of mature Litsea cubeba mother trees. Cut the branches to a length of 50cm, tie them into bundles, seal them in plastic film, and store them in a 2℃ low-temperature cold storage as scions. Take them out before grafting.

[0062] S2. Preparation of rootstock: Select a healthy 2-year-old Litsea cubeba stem with no diseases or pests, a ground diameter of 0.7cm, and cut it 6cm from the ground. Make a vertical downward cut on one side of the cut, so that the width of the cut is the same as the width of the scion's large oblique surface. Then, make a 1cm oblique cut from the outside to the inside 3cm from the ground, remove the upper part of the bark with the wood to expose the cut surface, and obtain the rootstock.

[0063] S3. Grafting: Take out the scion and seal it with wax. When cutting, leave two plump buds at the top and cut a large slant 3cm long at the bottom. Then cut a small slant 1cm long on the back. The cut surface of the scion should be symmetrical, flat and smooth on both sides. The large slant of the scion should be 0.5cm longer than the cut of the rootstock, so that the upper part of the large slant of the scion protrudes 0.5cm from the cut surface of the rootstock. Place the modified gel sheet on the surface of the rootstock cut. Soak the scion in a 5% sodium chloride solution for 4 minutes. Take it out and air dry at room temperature. Insert the scion into the rootstock cut, so that the rootstock and scion are tightly attached to both sides of the modified gel sheet. Make sure that they are tightly connected from top to bottom and left to right. Then tie the grafting interface tightly with the prepared plastic film strip.

[0064] S4. Post-grafting management: After grafting, water to keep the soil and rootstock moist. To prevent rootstock suckers from competing with the new shoots of the scion for nutrients, remove any new shoots that sprout from the rootstock in a timely manner, repeating this process five times. When the new scion reaches a length of about 30cm, remove the plastic strip. At the same time, strengthen water and fertilizer management and pest and disease control.

[0065] Comparative Example 5: Grafting Propagation of Litsea cubeba

[0066] Compared with Example 4, the difference in Comparative Example 5 is that the depth of the scion's large bevel and the rootstock incision are the same in S3. The remaining steps and raw materials are the same. S3 is as follows:

[0067] S3. Grafting: Take out the scion and seal it with wax. When cutting, leave two plump buds at the top and cut a large slant 3cm long at the bottom. Then cut a small slant 1cm long on the back. The cut surface of the scion should be symmetrical, flat and smooth on both sides. The length of the large slant of the scion should be equal to the depth of the rootstock cut, that is, the length of the rootstock cut and the large slant of the scion should fit together completely. Place the modified gel sheet on the surface of the rootstock cut. Soak the scion in a 5% sodium chloride solution for 4 minutes. Take it out and air dry at room temperature. Insert the scion into the rootstock cut, so that the rootstock and scion are tightly attached to both sides of the modified gel sheet. Make sure that they are tightly connected from top to bottom and left to right. Then tie the grafting interface tightly with the prepared plastic film strip.

[0068] Litsea cubeba grafting experiment:

[0069] The experiment was conducted on March 20, 2022, at the National Litsea cubeba Seed Base in Wanzhou District, Chongqing. A randomized block design was used, with 6 groups: experimental group 1 and control groups 1-5. Each group had 100 grafted plants, with three replicates.

[0070] Experimental Groups:

[0071] Experimental Group 1: The modified gel sheet prepared in Example 1 was selected, and the grafting method used was the grafting propagation method in Example 4;

[0072] Control group 1: The modified gel sheet prepared in Comparative Example 1 was selected, and the grafting method was the grafting propagation method of Example 4.

[0073] Control group 2: The modified gel sheet prepared in Comparative Example 2 was selected, and the grafting method used was the grafting propagation method in Example 4;

[0074] Control group 3: The modified gel sheet prepared in Comparative Example 3 was selected, and the grafting method used was the grafting propagation method in Example 4.

[0075] Control group 4: The modified gel sheet prepared in Comparative Example 4 was selected, and the grafting method was the grafting propagation method of Example 4.

[0076] Control group 5: The modified gel sheet prepared in Example 1 was selected, and the grafting method was the same as that in Comparative Example 5.

[0077] Experimental method: Before grafting healing, each group was watered once every 3 days, and after healing, once every 5 days. Watering was avoided to prevent splashing onto the graft union. The experiment was repeated three times. The grafting healing and survival rate of each group were observed and statistically analyzed. Survival rate = (Number of scion buds sprouting 40 days after grafting / Number of grafted plants) × 100%.

[0078] Table 1

[0079]

[0080] Analysis of Table 1 shows that:

[0081] 1. Compared with experimental group 1, control groups 1, 2, 3, and 4 differed only in the composition of the modified gel sheet. Although control group 1 showed better healing at 14 days, the callus formation time was delayed by one day compared to experimental group 1. At 14 days, only 63 callus plants formed, resulting in a 21% decrease in survival rate compared to experimental group 1. This is because the modified gel sheet prepared in control group 1 did not contain calcium chloride solution, thus failing to form a sheet-like gel and prolonging the callus formation time. However, the remaining components in the gel-like substance of control group 1 still possessed certain antibacterial and callus-promoting abilities.

[0082] 2. Control group 2 lacked the raw materials calcium chloride and hyaluronic acid, while control group 3 lacked the raw material methyl 4-hydroxy-3-methoxycinnamate. The healing progress of control groups 2 and 3 was generally poor at 14 days, with callus formation delayed by two days compared to experimental group 1. The number of callus-forming plants at 14 days were 58 and 58 respectively, with survival rates decreasing by 27% and 30% compared to experimental group 1. Control group 4's modified gel sheet did not have a dispersion solution prepared (i.e., nano-silica powder and polyacrylamide dispersed in water). At 14 days post-grafting, the healing progress of control group 4 was poor, with callus formation only appearing 7 days after grafting, and a survival rate of only 38%. Without nano-silica powder and polyacrylamide loaded onto sodium alginate and hyaluronic acid, it could not cause an increase in the local pH and osmotic pressure. The addition of methyl 4-hydroxy-3-methoxycinnamate in experimental group 1 not only enhances the resistance of Litsea cubeba cells, resists bacterial invasion, and accelerates callus formation, but also makes nano-silica more easily dispersed in the molecular chain and improves the stability of methyl 4-hydroxy-3-methoxycinnamate in the modified gel sheet. The modified gel sheet prepared by this invention not only has good bactericidal effects but also promotes callus formation, thereby improving the grafting survival rate of Litsea cubeba.

[0083] 3. Compared with experimental group 1, control group 5 had a scion incision length equal to that of the rootstock incision. After grafting and healing, a large nodule formed by proliferating tissue bulged at the lower part of the graft union, leading to the death of some xylem at the graft union of the rootstock and resulting in poor healing. At 14 days, the number of plants with callus formation was 65, and the survival rate was 22% lower than that of experimental group 1. Experimental group 1 showed better results in terms of long-term survival rate, healing condition, and short-term callus formation time.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications and substitutions should be covered within the scope of the claims of the present invention. Technical aspects, shapes, and structures not described in detail in this invention are all well-known technologies.

Claims

1. A grafting propagation method for Litsea cubeba, characterized in that, Specifically, the following steps are included: S1. Preparation of scions: From the winter of the previous year to the spring of the following year, select healthy, semi-lignified branches of 1-year-old Litsea cubeba from the periphery of mature mother trees. Cut the branches to a length of 50-60cm, tie them into bundles, seal them with plastic film, and store them in a cold storage at 0-4℃ as scions. Take them out before grafting. S2. Preparation of rootstock: Select the stems of healthy Litsea cubeba seedlings that are 1-2 years old and have a ground diameter of 0.4-0.8cm and cut them to obtain the rootstock; S3. Grafting: Take out the scion and cut it. Place the modified gel sheet on the surface of the rootstock cut. Soak the scion in a 5% sodium chloride solution for 3-5 minutes. After taking it out and air drying, insert it into the rootstock cut. Then tie the grafting point tightly with the prepared plastic film strip. S4. Post-grafting management: After grafting, water to keep the soil moist, and carry out water and fertilizer management and pest and disease control. When cutting the scion in step S3, the cut surface should be symmetrical, flat and smooth on both sides. The large bevel of the scion should be 0.4-0.6cm longer than the cut depth of the rootstock, so that the upper part of the large bevel of the scion protrudes 0.4-0.6cm from the cut surface of the rootstock. The preparation method of the modified gel tablets is as follows: (1) Weigh calcium chloride to prepare a calcium chloride solution with a mass fraction of 4%; add nano silica powder and polyacrylamide together to water, stir and disperse at a rate of 200-300 r / min to prepare a dispersion; (2) Weigh out sodium alginate and hyaluronic acid, dissolve them in water and mix them. Add methyl 4-hydroxy-3-methoxycinnamate and calcium chloride solution and stir. Then add dispersion, adjust pH, stir again, and finally add dipentaerythritol and stir for 20-40 min. Ultrasound for 10-20 min, pour into a silicone mold and solidify to obtain modified gel sheet. The modified gel sheet in step S3 comprises the following raw materials: 10-100 parts by weight of hyaluronic acid, 10-100 parts by weight of sodium alginate, 0.1-3 parts by weight of methyl 4-hydroxy-3-methoxycinnamate, 1-9 parts by weight of dipentaerythritol, 1-20 parts by weight of nano silica powder, 1-8 parts by weight of calcium chloride, and 0.2-2 parts by weight of polyacrylamide.

2. The grafting propagation method for Litsea cubeba according to claim 1, characterized in that, The specific cutting process of the rootstock in step S2 is as follows: Cut the rootstock 4-6cm from the ground, make a vertical downward cut on one side of the cut, so that the width of the cut is the same as the width of the large bevel of the scion, and then make a 0.8-1.2cm oblique cut from the outside to the inside at 2.5-3.5cm from the ground, and remove the upper part of the bark with wood to expose the cut surface.

3. The grafting propagation method for Litsea cubeba according to claim 2, characterized in that, The specific cutting process of the scion in step S3 is as follows: Take out the scion and seal it with wax. When cutting, leave 1-2 plump buds at the top, cut a large slant 2.5-3.5cm long at the bottom, and then cut a small slant 0.8-1.2cm long on the back.

4. The grafting propagation method for Litsea cubeba according to claim 1, characterized in that, The modified gel sheet in step S3 comprises the following raw materials: 20-40 parts by weight of hyaluronic acid, 20-40 parts by weight of sodium alginate, 0.2-1 parts by weight of methyl 4-hydroxy-3-methoxycinnamate, 3-7 parts by weight of dipentaerythritol, 5-10 parts by weight of nano silica powder, 2-6 parts by weight of calcium chloride, and 0.5-1 parts by weight of polyacrylamide.

5. The grafting propagation method for Litsea cubeba according to claim 4, characterized in that, When preparing the modified gel sheet, the pH adjustment operation in step (2) is as follows: adjust the pH to 6.8-7.3 with 0.05mol / L potassium dihydrogen phosphate-sodium hydroxide buffer.

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