High-survival-rate method for grafting pinus sylvestris on pinus sylvestris in alpine region

Abstract

The invention discloses a high-survival-rate method for grafting pinus sylvestris on pinus sylvestris in an alpine region. The grafting adaptability and the survival rate are improved through multi-dimensional innovation. A rising slope is arranged on the sunny side of a pinus sylvestris rootstock, double connectors of a falling slope are arranged on the shady side of the pinus sylvestris rootstock and matched with double wedge-shaped parts of Tibetan white bark pine scion buds, and the rootstock-scion contact face is increased; a photo-thermal response shape memory polymer bandage is adopted for fixation, germs are inhibited, and callus differentiation is promoted; a double-layer protection structure is constructed, a humidity control group is arranged in an inner-layer moisturizing breathable film to maintain the humidity of a connector to be larger than or equal to 60%, and an outer-layer anti-UV windproof net is intelligently adjusted to cope with sand wind and strong light. Furthermore, the callus differentiation is accurately regulated and controlled by pre-embedding pH responsive cellulose microspheres, or an intelligent temperature control film and an aerogel layer are additionally arranged to stabilize the temperature difference, and the freezing resistance is enhanced in combination with scion bud low-temperature domestication and abscisic acid treatment. The method remarkably improves the grafting survival rate, is suitable for efficient introduction of the Tibetan white bark pine in the alpine region, and is high in process synergy and high in environmental adaptability.

Description

Technical Field

[0001] The invention relates to the technical field of Scots pine grafting, and more specifically to a method for grafting Scots pine onto Tibetan white pine in high-cold areas with a high survival rate. Background Art

[0002] Plant grafting technology faces huge challenges in alpine areas due to the harsh environment such as extreme low temperatures, strong ultraviolet radiation and frequent strong winds. As a cold-resistant rootstock, Larix gmelinii is widely used in afforestation in alpine areas, and its grafting technology with tree species such as Pinus koraiensis and Pinus tabulaeformis has a certain research foundation. In the invention patent with publication number CN118020513A, it is proposed to protect the scion buds by double-covering plastic bottles and applying potassium fertilizer to promote lignification for the grafting of Larix gmelinii onto Pinus koraiensis, which significantly improves the survival rate of Larix gmelinii grafted onto Pinus koraiensis. However, this method is mainly aimed at Pinus koraiensis scion, and whether its technical logic (such as protection measures and fertilizer ratios) is applicable to other pine species still needs to be verified, especially the grafting research of the special species of Tibetan white pine is still blank.

[0003] Tibetan white pine has both ecological restoration and economic value. Its wood is dense and resistant to adversity, and it has great potential in ecological construction in the arid areas of western China. Tibetan white pine is distributed in a narrow range around the world. Because of its large seeds, thin skin and abundant flesh, high nutritional value and good taste, it has a strong market demand. However, it takes 20 years for naturally grown Tibetan white pine to produce pine cones.

[0004] So far, there has been no systematic study on the grafting technology of Tibetan white pine and Scots pine. Existing literature mostly focuses on the grafting compatibility of Scots pine with common tree species such as Korean pine and Chinese pine. However, due to the differences in physiological characteristics of Tibetan white pine (such as slow callus differentiation rate and special low-temperature metabolic pathways), traditional grafting methods are difficult to apply directly. For example, the static protection of plastic bottles in the invention patent CN118020513A can prevent wind and keep warm, but it fails to solve the periodic micro-displacement of the scion interface caused by the temperature difference between day and night in high-altitude cold areas. Due to the difference in thermal expansion coefficients, the Tibetan white pine scion and the Scots pine rootstock are prone to shear stress under temperature fluctuations, resulting in only partial connection of the internal vascular bundles of the seemingly healed interface. In addition, the Tibetan white pine scion buds are more sensitive to humidity fluctuations, and the closed environment is prone to interface mildew or freeze-thaw damage, resulting in a low survival rate.

[0005] From the perspective of the interaction mechanism between the rootstock and scion, the affinity between Tibetan white pine and Pinus sylvestris has not yet been clarified. Existing grafting techniques are mostly based on morphological matching (such as alignment of the cambium), but the vascular bundle structure and hormone response characteristics of Tibetan white pine are significantly different from those of Pinus sylvestris. Although the cleft grafting method used in the invention patent CN118020513A is suitable for Pinus sylvestris, its scion bud cut length (3-5cm) and fertilization strategy (only potassium fertilizer) cannot meet the special needs of Tibetan white pine for nutrient distribution and interface healing rate. The Tibetan white pine scion contains unique terpene defense substances, such as α-pinene content of 2.3 times that of Pinus sylvestris. When it comes into contact with the rootstock of Pinus sylvestris, it triggers the rootstock trauma response system to release a large amount of methyl jasmonate. The metabolites of the two form a conflict zone at the interface, inhibiting lignin deposition and attracting saprophytic colonization. The invention patent CN118020513A only uses carbendazim for broad-spectrum sterilization, but fails to regulate the rootstock-scion immune dialogue in a targeted manner, resulting in necrosis of the graft due to chronic rejection. Studies have shown that the scion buds of Tibetan white pine require a higher concentration of auxin to activate the antifreeze gene, but the existing technology lacks targeted optimization of the scion bud pretreatment (such as low temperature acclimation and hormone induction).

[0006] In addition, the coordinated protection system for environmental stress in high-altitude cold regions has not yet been applied in the grafting of Tibetan white pine. Although the invention patent CN118020513A improves the survival rate of Korean pine through physical protection (plastic bottles) and potassium fertilizer management, its function is single and does not involve smart materials (such as photothermal response straps, pH controlled release antibacterial agents) and dynamic regulation of the microenvironment. After grafting, Tibetan white pine needs to accurately maintain interface humidity, inhibit ultraviolet damage and simultaneously release stress resistance factors, but the static moisturizing film and fixed straps in the existing technology are difficult to achieve multi-parameter coordinated adaptation. Therefore, the development of a dynamic adaptation method for grafting Pinus sylvestris var. mongolica to Tibetan white pine, combined with environmental response materials and physiological regulation strategies, has become a key direction to break through the bottleneck of grafting technology in high-altitude cold regions. Summary of the invention

[0007] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0008] Another object of the present invention is to provide a method for achieving a high survival rate of larch grafted onto Tibetan white pine in high-altitude cold regions, which improves the fit between the stock and scion through double-interface adaptation and asymmetric double-wedge scion bud design; the light-responsive intelligent binding strap dynamically adjusts the fixing force and slowly releases antibacterial and healing-promoting drugs; the double-layer protective structure synergistically controls moisture (≥60%), resists UV and is windproof, significantly improving the survival rate of larch grafted onto Tibetan white pine in high-altitude cold regions.

[0009] In order to achieve these purposes and other advantages according to the present invention, a method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold areas with high survival rate is provided, comprising: Step 1: Open a double interface on the larch, the first interface is located on the sunny side and cuts an ascending slope, the second interface is located on the shady side and cuts a descending slope, and the first interface and the second interface are connected through an incision; Step 2: Select the top bud branch of Tibetan white pine as the scion bud, and cut a double wedge-shaped portion that fits the first interface, the second interface and the incision on three sides; Step 3, the double wedge-shaped parts of the scion bud are respectively pressed against the double interfaces of the rootstock, and mechanically adapted and fixed by using a photothermal responsive shape memory polymer band, wherein the photothermal responsive shape memory polymer band is provided with a penetration hole; Step 4: after grafting, a double-layer protective structure is constructed outside the scion bud, wherein the inner layer of the double-layer protective structure is a moisturizing breathable film, and the outer layer is an anti-UV windproof net; Wherein, a soaked moisture control mass is arranged in the moisture-retaining breathable membrane to maintain the air humidity at the interface not less than 60% within 20 days.

[0010] like Figure 1 and Figure 2 In the above technical scheme, an ascending slope (inclination angle of 30-45°) is cut on the sunny side (southward) of the Scots pine stock as the first interface 1, with a depth to the cambium, and a descending slope (inclination angle of 30-45°) is cut on the shady side (northward) as the second interface 2. The two interfaces are connected through a cut. Through the double-slope difference design, the light and heat advantages of the sunny side are used to accelerate callus differentiation, and the contact surface on the shady side is extended to buffer the frost heave stress. The top bud branches of Tibetan white pine (preferably one-year-old) are selected, and the first wedge-shaped part 3 and the second wedge-shaped part 4 are cut to form a stepped transition at the connection. The first wedge-shaped part 3 fits the first sunny interface 1, and the short and thick structure is used to resist wind vibration. The second wedge-shaped part 4 fits the second shady interface 2, and the long and thin design increases the contact area of ​​the cambium. In particularly windy areas, the cut surface can be appropriately increased based on the concept of the first interface and the second interface, such as opening a spiral interface on the stock, cutting a reverse spiral wedge-shaped part on the scion bud, and increasing the torsional strength through spiral interlocking. When the band is wrapped, an initial pressure of 10~15N is applied. When the light intensity is >5000Lux, after the light and heat layer heats up, the hydrogel shrinks to reduce the binding force, avoiding strangulation when the scion bud expands. After the temperature drops at night, the hydrogel expands and rebounds to maintain a tight fit at the interface. 2) is set in the moisturizing breathable membrane to slowly release water vapor, and the humidity is stabilized at more than 60%, preferably at 60%~62%. The anti-UV windproof net shrinks its mesh aperture when the wind speed is greater than the threshold, reducing the air permeability. The wind speed threshold here varies according to the region, and is generally designed to be 4~8m / s. In the above technical scheme, the double interface + double wedge-shaped part synergizes to greatly increase the contact area of ​​the cambium and shorten the callus differentiation cycle; the asymmetric structure adapts to the temperature difference between the positive and negative sides of the rootstock (the temperature difference between day and night is large in high-altitude cold areas), reducing the risk of interface cracking. The photothermal response dynamic binding strap intelligently adjusts the binding force, avoids the "loose-tight" cycle damage caused by temperature changes to traditional binding straps, and improves the mechanical stability of the interface. The humidity control group offsets freeze-thaw fluctuations through the water absorption / release cycle, reduces the humidity fluctuation range, and has a high UV shielding rate to avoid light damage to the scion buds.

[0011] Preferably, the lengths of the first wedge-shaped portion 3 and the second wedge-shaped portion 4 of the double wedge-shaped portion are 2 cm and 4 cm respectively, and the thickness ratio of the connection between the first wedge-shaped portion 3 and the second wedge-shaped portion 4 is 1:2 (e.g. Figure 2 as shown).

[0012] Preferably, the photothermal responsive shape memory polymer bandage comprises, from outside to inside, a polycaprolactone / carbon nanotube composite photothermal conversion layer, a first poly N-isopropylacrylamide modified thermosensitive hydrogel layer and a drug-loaded porous polylactic acid fiber layer, wherein the carbon nanotube content in the polycaprolactone / carbon nanotube composite photothermal conversion layer is 0.5~1.2wt%, the LCST of the first poly N-isopropylacrylamide modified thermosensitive hydrogel layer is 28°C, and the drug-loaded porous polylactic acid fiber layer contains 10% by mass of nanosilver / de-earthed composite antibacterial agent, 5% of indolebutyric acid and β-cyclodextrin. When the temperature of the inner layer is higher than 28°C, the first poly N-isopropylacrylamide modified thermosensitive hydrogel layer undergoes a volume phase change to promote the sustained release rate of the drug in the drug-loaded porous polylactic acid fiber layer.

[0013] In the above technical scheme, polycaprolactone (PCL) and carbon nanotubes (CNTs) are mixed in a mass ratio, wherein the mass content of carbon nanotubes is 0.5~1.2%. For example, polycaprolactone and carbon nanotubes are mixed in a mass ratio of 98.8:1.2, and a thin film with a thickness of 0.5 mm is made by melt blending. The photothermal conversion efficiency reaches 85% (heating to 35°C at a light noise intensity of 5000Lux). Under strong light during the day, CNTs absorb light energy and convert it into heat energy, triggering a phase change of the temperature-sensitive layer. The critical solution temperature (LCST) of the first poly N-isopropylacrylamide (PNIPAM) modified hydrogel is adjusted to 28°C through copolymerization modification (such as PNIPAM-co-BMA). When the inner layer temperature is greater than 28°C (precisely matching the temperature fluctuation of -5~25°C in high-cold areas, under the action of the photothermal outer layer, the inner layer temperature is generally 3~6°C higher than the ambient temperature), the first poly N-isopropylacrylamide modified thermosensitive hydrogel layer shrinks (volume decreases) to squeeze the inner layer of drug-loaded fibers to promote drug release. At night, when the inner layer temperature is less than 28°C, the modified hydrogel expands to restore the initial volume, reducing the drug release rate and avoiding Excessive drug consumption; porous polylactic acid fibers are uniformly loaded with nanosilver / desilvered composite antibacterial agent (mass fraction 10%, the mass of nanosilver / desilvered composite antibacterial agent is 10% of the mass of the polylactic acid fiber layer, the mass proportion of nanosilver in the nanosilver / desilvered composite antibacterial agent is 20%, and the mass proportion of desilver in the nanosilver / desilvered composite antibacterial agent is 80%), indolebutyric acid (5%) and β-cyclodextrin to encapsulate drug molecules to extend the sustained-release period (at least 20 days). When the inner layer temperature is greater than 28°C, the pressure generated by the contraction of the first poly N-isopropylacrylamide modified thermosensitive hydrogel layer increases the fiber porosity and improves the drug release rate. In the above technical scheme, the photothermal-thermosensitive synergistic trigger mechanism (dual signal linkage of light and temperature) is used to achieve a precise match between the drug release rate and the interface healing needs. High temperature during the day accelerates the release of antimicrobial agents, and low temperature at night reduces drug waste, improves the antimicrobial efficiency of the interface, and shortens the callus differentiation cycle. At the same time, the nanosilver / de-earthed composite antimicrobial agent inhibits common low-temperature pathogens (such as Fusarium) in high-altitude cold areas, indolebutyric acid promotes callus proliferation, and β-cyclodextrin prolongs the drug action period and reduces the frequency of drug application. The thermosensitive layer is modified to adjust the LCST to 28°C to ensure that the temperature difference between day and night in the high-altitude cold areas (25°C during the day and -5°C at night. Under the intervention effect of the photothermal outer layer, the temperature of the inner layer can rise to above 28°C) can still respond effectively, avoiding false triggering by low temperature and inability to adapt to the high-altitude cold environment.

[0014] Preferably, the outer layer of the anti-UV windproof net is woven with shape memory polyurethane fibers, and when the ambient wind speed exceeds the wind speed threshold, the mesh aperture automatically shrinks by 40-60%; the inner layer of the moisturizing and breathable membrane is a polyvinyl alcohol / polyethylene glycol blended polymer membrane as a basic skeleton, and is cross-linked and modified by glutaraldehyde to form a three-dimensional grid structure, and the inner layer of the moisturizing and breathable membrane is embedded with thermosensitive hydrogel microcapsules, and the LCST of the thermosensitive hydrogel microcapsules is 15°C. When the temperature is lower than 15°C, the thermosensitive hydrogel microcapsules release gibberellin A3.

[0015] In the above technical solution, the outer layer of anti-UV windproof net is woven with shape memory polyurethane fiber (SM-PU) with a fiber diameter of 50μm and an initial mesh aperture set to 2~4mm. Thermotropic liquid crystal unit (TLC) is embedded in the shape memory polyurethane fiber. When the ambient wind speed exceeds the threshold (generally set to 4~8m / s, which can be fine-tuned according to different regions), the wind pressure triggers the TLC phase change, and the fiber shrinks to reduce the mesh aperture by 40~60%, thereby reducing the air permeability. Polyvinyl alcohol and polyethylene glycol are blended in a mass ratio of 7:3, and 0.5% glutaraldehyde cross-linking agent is added to form a three-dimensional grid membrane with a thickness of 0.1-0.2 mm and a porosity of 60%. Thermosensitive hydrogel microcapsules are embedded in the inner moisturizing and breathable membrane. When the temperature is lower than 15°C, the thermosensitive hydrogel microcapsules release gibberellin A3 to induce antifreeze genes in the scion buds. Because the double-layer protective structure is outside the photothermal responsive shape memory polymer band, its surrounding temperature is lower than the temperature inside the photothermal responsive shape memory polymer band, and the released gibberellin A3 enters the interface through the penetration hole and acts on the scion bud.

[0016] In the above technical scheme, when the wind speed exceeds the threshold, the aperture of the outer anti-UV windproof net is reduced to reduce wind pressure, thereby improving windproof efficiency. The humidity of the polyvinyl alcohol / polyethylene glycol three-dimensional grid membrane is maintained above 60%, and the humidity fluctuation is small. The air permeability matches the callus breathing needs. The thermosensitive microcapsules accurately release GA3. A single load of gibberellin A3 can maintain an effective concentration for at least 20 days, and the low-temperature survival rate of the scion is increased by at least 50%, and the lignification rate is accelerated by more than 1.2 times. The cold resistance of SM-PU fiber reaches -30℃, and its life is 3 times longer than that of ordinary polyester nets. The tensile strength of the glutaraldehyde cross-linked membrane reaches 15MPa, which effectively avoids freeze-thaw cracking.

[0017] Preferably, the gibberellin A3 is encapsulated by a second poly N-isopropylacrylamide modified hydrogel, the second poly N-isopropylacrylamide modified hydrogel swells at low temperatures to release gibberellin A3 to improve the low-temperature stress resistance of the scion bud, and the second poly N-isopropylacrylamide modified hydrogel is formed by copolymerizing N-isopropylacrylamide (NIPAM) and butyl methacrylate (BMA) in a molar ratio of 9:1, and its LCST is reduced to about 15°C. The second poly N-isopropylacrylamide (PNIPAM) modified hydrogel had its lower critical solution temperature adjusted to 15°C through copolymerization modification, so that it swelled at low temperatures. Gibberellic acid A3 solution (concentration of 0.1 mg, mL) was mixed with β-cyclodextrin to form an inclusion complex to enhance stability. The gibberellin A3 solution was mixed with the PNIPAM prepolymer, and oil-in-water droplets were formed by emulsification. A cross-linking agent was added, and ultraviolet light was used to initiate polymerization to form microcapsules with a particle size of 50~100 μm. The mass fraction of gibberellin A3 in the microcapsules was 8~10%. Through the design of encapsulating gibberellin A3 with thermosensitive hydrogel, the precise release and efficient utilization of antifreeze factors under low temperature stress are achieved, forming temporal and spatial complementarity with the windproof function of the windbreak net. In the present invention, the PNIPAM hydrogel is non-toxic and degradable, avoiding allelopathic inhibition at the interface. According to the difference in temperature difference in different high-cold areas, on the basis of following the LCST value of the first poly N-isopropylacrylamide modified hydrogel being greater than the LCST value of the second poly N-isopropylacrylamide modified hydrogel, the LCST of the first poly N-isopropylacrylamide modified hydrogel and the second poly N-isopropylacrylamide modified hydrogel can be appropriately adjusted.

[0018] Preferably, the surface of the anti-UV windproof net is coated with a photochromic nano coating, which is composed of vanadium dioxide and tungsten oxide composite nanowires. When the ultraviolet intensity is greater than the ultraviolet intensity threshold, the refractive index of the coating is automatically lowered, so that the light transmittance of the windproof net is reduced by 40-50%. The photochromic nano coating is composed of vanadium dioxide and tungsten oxide composite nanowires, and the function of shielding ultraviolet rays is achieved by reflecting and scattering ultraviolet rays. The ultraviolet shielding rate is greater than 90% (wavelength 280-400nm).

[0019] Preferably, the moisture control group includes, from the inside to the outside, a sodium polyacrylate water-absorbent resin compressed core with a thickness of 5:3:5, a spirally wound cotton wool fiber and a polylactic acid porous membrane, wherein the water absorption rate of the sodium polyacrylate water-absorbent resin compressed core is 500-800 times, and the sodium polyacrylate water-absorbent resin compressed core releases bound water when the daytime temperature is >5°C, and recaptures condensed water in the polylactic acid porous membrane when the nighttime temperature is <0°C; the diameter of the cotton wool fiber is 10-15 μm, and the pore size of the polylactic acid porous membrane is 50-100 μm.

[0020] In the above technical solution, the inner layer of sodium polyacrylate water-absorbent resin compression core is formed by high-pressure compression of sodium polyacrylate particles, with a water absorption rate of 500-800 times (i.e. 1g of resin absorbs 500-800g of water). When the daytime temperature is >5°C, the thermal motion of the resin molecular chain is enhanced, releasing bound water. When the nighttime temperature is <0°C, the resin shrinks and re-absorbs the condensed water in the polylactic acid porous membrane. The middle layer of spirally wound absorbent cotton fibers is made of absorbent cotton fibers with a diameter of 10-15μm and a spiral angle of 60°. The gap rate of the spirally wound absorbent cotton fibers is 40%. As a water conduction channel, the spiral structure guides the water to diffuse evenly from the core to the outer layer of polylactic acid porous membrane to avoid local water accumulation or drying. The outer layer of polylactic acid porous film adopts thermally induced phase separation method, with a pore size of 80μm and a porosity of 70%. When the temperature is low at night, condensation forms on the membrane surface, which infiltrates back to the spirally wound absorbent cotton fibers in the middle layer through capillary action and is finally adsorbed by the compressed core of the sodium polyacrylate absorbent resin in the inner layer. In the above technical solution, its temperature response humidity cycle mechanism is as follows: During the day (>5℃), the inner layer of sodium polyacrylate water-absorbing resin compresses the core to release bound water → the middle layer of spirally wound absorbent cotton fibers conducts water to the outer layer of polylactic acid porous membrane → water vapor is slowly released through the pores of the porous membrane to maintain humidity at 60~62%; At night (<0℃), condensed water is generated on the surface of the polylactic acid porous membrane → absorbed by the spirally wound absorbent cotton fibers in the middle layer → adsorbed and stored by the compressed core of the sodium polyacrylate absorbent resin in the inner layer, and the humidity fluctuation is ≤2%.

[0021] In the above technical solution, the inner layer of sodium polyacrylate water-absorbing resin compressed core has a water absorption capacity of 500~800 times, which can store the required moisture at the interface for at least 20 days. Combined with the temperature response release, the humidity is stabilized at 60~62%, and condensed water is captured at night to avoid freezing and expansion that cause cracking of the interface, thereby reducing the rate of frost damage. The moisture control group adopts a multi-layer design to achieve gradient management of moisture. The high water absorption of the inner layer ensures water reserves, the middle layer achieves uniform diffusion of moisture, and the outer layer controls the release of water vapor and recovers condensed water, with a utilization rate of over 90%. At the same time, the inner layer of sodium polyacrylate water-absorbing resin compressed core has high compressive strength and can support the structure without deformation. The outer layer of polylactic acid porous membrane can withstand low temperatures of -20°C and has a long service life, making it suitable for high-cold areas.

[0022] Preferably, pH-responsive cellulose microspheres are pre-embedded in the spirally wound absorbent cotton fibers, and the pH-responsive cellulose microspheres are loaded with 15% by mass of potassium humate and 5% by mass of trehalose. When the pH at the interface changes to 6.2-6.5 due to callus metabolism, the wall material of the pH-responsive cellulose microspheres dissolves to release potassium humate to promote callus cell differentiation, while trehalose and sodium polyacrylate water-absorbent resin compress the moisture in the core to form a hydrogen bond grid, thereby stably regulating the air humidity to above 60%.

[0023] In the above technical scheme, pH-responsive cellulose microspheres are embedded in spirally wound absorbent cotton fibers, and the microspheres are loaded with 15% by mass of potassium humate and 5% by mass of trehalose. When the pH at the interface changes to 6.2-6.5 due to callus metabolism, the wall material of the pH-responsive cellulose microspheres rapidly dissolves and releases the potassium humate and trehalose therein. Through pH-responsive cellulose microspheres, potassium humate can be accurately released at the critical stage of callus metabolism at the interface, that is, when the pH reaches 6.2-6.5, avoiding the adverse effects on cell differentiation too early or too late, greatly improving the efficiency and quality of callus healing, and precise regulation can shorten the healing time of callus. The released potassium humate exerts its effect of promoting cell differentiation, accelerates the differentiation process of callus cells, and helps the grafted site heal faster and better. Trehalose and sodium polyacrylate water-absorbing resin compress the moisture in the core to form a hydrogen bond grid. This is because of the special chemical structure of trehalose, which can closely bind to moisture, thereby stably regulating the air humidity at more than 60%, providing a continuous and suitable humidity environment for the grafting interface. Trehalose and sodium polyacrylate water-absorbing resin compress the moisture in the core to form a hydrogen bond grid, which can effectively stabilize the air humidity. Under the complex and changeable climatic conditions in high-altitude cold areas, ordinary moisturizing methods are difficult to maintain stable humidity, and this design can ensure that the air humidity at the interface is always not less than 60% within 20 days, providing a stable humidity guarantee for successful grafting. Experimental verification shows that the grafting survival rate using this design is indeed higher than that not using it.

[0024] In the above technical scheme, various materials such as pH-responsive cellulose microspheres, potassium humate, trehalose and sodium polyacrylate absorbent resin compressed core cooperate with each other to form a complete synergistic system from environmental perception (pH changes) to substance release (potassium humate and trehalose), to promoting healing (potassium humate promotes cell differentiation) and stabilizing the environment (trehalose stabilizes humidity), which fully utilizes the advantages of each material and greatly improves the overall effect of the grafting method.

[0025] Preferably, an intelligent temperature control membrane and an aerated gel insulation layer made of phase change material are also provided between the moisturizing breathable membrane and the anti-UV windproof net, and the intelligent temperature control membrane is arranged close to the moisturizing breathable membrane. An intelligent temperature control membrane and an aerated gel insulation layer are added between the double-layer protective structure (inner moisturizing breathable membrane, outer anti-UV windproof net), wherein the intelligent temperature control membrane is made of phase change material, such as paraffin and fatty acids, and is tightly attached to the outer side of the inner thermal insulation breathable membrane, and the latent heat characteristics of the phase change material are used to absorb or release heat. When the temperature rises, such as when the light is strong during the day, the phase change material absorbs heat and changes from solid to liquid, suppressing the sudden rise in temperature at the interface. When the temperature drops, such as at ultra-low temperatures at night, the phase change material changes from liquid to solid to release latent heat, avoiding a sudden drop in temperature at the interface. The aerogel insulation layer is filled between the intelligent temperature control membrane and the outer windproof net. It is composed of a porous structure of aerogel materials, such as silica aerogel, which forms thermal resistance by trapping air, reduces the impact of external temperature fluctuations on the interface, further blocks the exchange of external hot and cold air, and cooperates with phase change materials to make the temperature difference between day and night at the interface fluctuate. Through active temperature control, the limitations of passive insulation are broken through. Traditional grafting protection relies on insulation materials to passively block heat, which is difficult to cope with the drastic temperature difference in high-altitude cold areas. The intelligent temperature control membrane uses the "heat cache" function of phase change materials and combines the efficient insulation of aerogel to achieve active regulation of the temperature at the interface, avoid high temperature burns or low temperature freezing and cracking of callus tissue, and stabilize the interface temperature in a range suitable for healing. The stable temperature environment can maintain the cell division activity of the cambium layer and shorten the callus formation time. The composite design of phase change materials and aerogels forms a "temperature control + insulation" double barrier to block long-term low temperature conduction. It is especially suitable for extreme day and night temperature differences in high-altitude cold areas and can improve the survival rate of grafting.

[0026] Preferably, the scion bud is placed in a -5℃~0℃ environment for 24h before grafting, and a 50~100μM abscisic acid solution is sprayed synchronously to induce the expression of antifreeze protein genes, simulate the low temperature stress environment after grafting in high-cold areas, and induce the scion bud to start the stress resistance physiological mechanism. During the low-temperature acclimation process, a 50~100μM abscisic acid is sprayed synchronously, and absorbed by leaves or buds to activate the expression of antifreeze protein genes and promote the accumulation of antifreeze substances such as proline and soluble sugars. The pretreated scion bud can adapt to the low temperature environment faster after grafting, reduce the healing delay or failure caused by frost damage, and improve the synchronization of the cambium differentiation of the scion and the stock. It is especially suitable for high-cold areas with a short growing season, and can effectively extend the healing time window.

[0027] The present invention has at least the following beneficial effects: First, the present invention innovatively proposes to use Pinus sylvestris var. mongolica, which has strong stress resistance and wide distribution in the west, as the rootstock to carry out dwarfing grafting on Pinus pilosa. After experiments, it has been successfully achieved that Pinus pilosa bears fruit at least fifteen years earlier. Compared with the long cycle of natural growth that takes twenty years to produce pine cones, the results of the present invention have greatly shortened the economic return cycle of Pinus pilosa. It has not only significantly improved the economic benefits of local forestry, but also strongly promoted the development of related industries such as food processing using Pinus pilosa seeds as raw materials. In addition, through large-scale dwarfing grafting, it can accelerate its planting and promotion in the arid areas of the west, improve the local ecological environment, and achieve a virtuous cycle of ecology and economy. Secondly, the high survival rate method of larch grafted with Tibetan white pine in high-cold areas provided by the present invention significantly improves the contact area between the rootstock and scion and the alignment accuracy of the cambium through the double interface design of the rising slope on the sunny side and the descending slope on the shady side, and promotes the efficient differentiation of callus tissue, solves the problem of insufficient lamination of the traditional single interface, and improves the survival rate of larch grafted with Tibetan white pine; Third, the high survival rate method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-altitude cold regions provided by the present invention applies the concept of dynamic intelligent regulation in Pinus sylvestris var. mongolica grafting. By embedding a polycaprolactone / carbon nanotube photothermal layer and a thermosensitive hydrogel-level drug-loaded fiber layer in the binding strap, when the temperature is greater than 15°C, the drug sustained release (nanosilver antibacterial, indolebutyric acid promotes healing) is triggered, and the binding force is adaptively adjusted as the scion bud expands, thereby avoiding mechanical damage, improving the antibacterial efficiency, and shortening the interface healing cycle. Fourthly, the high survival rate method of grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-altitude cold regions provided by the present invention adopts an inner layer of moisturizing breathable membrane (embedded with thermosensitive hydrogel microcapsules) combined with an outer layer of anti-UV protective net (photochromic coating), the humidity is stable ≥ 60%, the ultraviolet shielding rate is > 90%, and the mesh size is reduced by 40-60% when the wind speed exceeds the threshold, which solves the problems of traditional plastic bottles being airtight and mildewed, fixed light transmittance and insufficient windproof; Fifth, in the method for achieving high survival rate of Pinus sylvestris grafted with Pinus tibetana in high-cold areas provided by the present invention, the scion buds are pre-placed in a -5°C to 0°C environment and sprayed with abscisic acid to activate the expression of antifreeze protein genes, and combined with the low-temperature release of gibberellin A3 in the membrane, the stress resistance of the scion buds is enhanced, which greatly improves the low-temperature survival rate of Pinus sylvestris grafted with Pinus tibetana; Sixth, in the method for achieving high survival rate of Pinus sylvestris grafted onto Pinus bungeana in high-altitude cold regions provided by the present invention, the moisture-controlled mass accurately releases the healing-promoting components and adjusts the humidity fluctuation at the interface pH of 6.2-6.5 through the water absorption / release cycle of the sodium polyacrylate core and the pH-responsive microspheres (potassium humate and trehalose), which not only improves the utilization rate of sodium humate, but also accelerates the callus differentiation rate; Seventh, in the method for achieving high survival rate of larch grafted with Tibetan white pine in high-altitude cold areas provided by the present invention, the windbreak net is coated with a vanadium dioxide / tungsten oxide photochromic layer. When the ultraviolet light is greater than a threshold value, the light transmittance is reduced by 40-50%. The aerated gel layer of the intelligent temperature control membrane box buffers the temperature difference between day and night, reduces temperature fluctuations at the interface, avoids freeze-thaw damage, and improves lignification efficiency.

[0028] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A schematic diagram of the first interface and the second interface in a technical solution of the present invention; Figure 2 It is a schematic structural diagram of the double wedge-shaped portion in another technical solution of the present invention.

[0030] Among them, 1. first interface; 2. second interface; 3. first wedge-shaped portion; 4. second wedge-shaped portion. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0032] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0033] Example 1 Step 1: an ascending slope (with an angle of 45° to the horizontal plane) is cut on the sunny side (southward) of the Scotch pine rootstock to a depth of the cambium, and a descending slope (with an angle of 45° to the horizontal plane) is cut on the shady side (northward) to a depth of the cambium, and the first interface and the second interface are connected through an incision; Step 2: Cut the one-year-old terminal bud of Tibetan white pine as the scion bud, and cut an asymmetrical double wedge-shaped part. Figure 2 As shown, the first wedge is 2 cm long and the second wedge is 4 cm long; Step three, fit the double wedge-shaped part of the scion bud with the double interface of the stock, and fix it with a photothermal responsive shape memory polymer bandage, wherein the photothermal responsive shape memory polymer bandage includes a polycaprolactone / carbon nanotube composite photothermal conversion layer, a first poly N-isopropylacrylamide modified thermosensitive hydrogel layer and a drug-loaded porous polylactic acid fiber layer from the outside to the inside, wherein the carbon nanotube content in the polycaprolactone / carbon nanotube composite photothermal conversion layer is 1.2wt%, the LCST of the first poly N-isopropylacrylamide modified thermosensitive hydrogel layer is 28°C, and the drug-loaded porous polylactic acid fiber layer contains 10% by mass of nanosilver / de-earthed composite antibacterial agent, 5% of indolebutyric acid and β-cyclodextrin; Step 4: construct a double-layer protective structure. The outer UV-resistant windproof net is woven with shape memory polyurethane fibers. When the ambient wind speed exceeds the wind speed threshold, the mesh aperture automatically shrinks by 60%; the inner moisturizing breathable membrane is a polyvinyl alcohol / polyethylene glycol blended polymer membrane as the basic skeleton, and is cross-linked and modified by glutaraldehyde to form a three-dimensional grid structure. The inner moisturizing breathable membrane is embedded with a second poly N-isopropylacrylamide modified hydrogel microcapsule. The LCST of the second poly N-isopropylacrylamide modified hydrogel microcapsule is 15°C. When the temperature is lower than 15°C, the thermosensitive hydrogel microcapsule releases gibberellin A3. A soaked moisture control group is provided in the moisturizing and breathable membrane, and the moisture control group includes, from the inside to the outside, a sodium polyacrylate water-absorbent resin compressed core with a thickness of 5:3:5, a spirally wound cotton wool fiber and a polylactic acid porous membrane, wherein the water absorption ratio of the sodium polyacrylate water-absorbent resin compressed core is 800 times, and the sodium polyacrylate water-absorbent resin compressed core releases bound water when the daytime temperature is >5°C, and recaptures condensed water in the polylactic acid porous membrane when the nighttime temperature is <0°C; the diameter of the cotton wool fiber is 15μm, and the pore size of the polylactic acid porous membrane is 100μm.

[0034] Example 2 Step 1, same as in Example 1; Step 2: Same as in Example 1; Step 3, same as in Example 1; Step 4. On the basis of Example 1, pH-responsive cellulose microspheres are pre-embedded in the spirally wound absorbent cotton fibers, and the pH-responsive cellulose microspheres are loaded with 15% by mass of potassium humate and 5% by mass of trehalose. When the pH at the interface changes to 6.5 due to callus metabolism, the wall material of the pH-responsive cellulose microspheres dissolves to release potassium humate to promote callus cell differentiation, while trehalose and sodium polyacrylate absorbent resin compress the moisture in the core to form a hydrogen bond grid, thereby stably regulating the air humidity to above 60%.

[0035] Example 3 Step 1, same as in Example 1; Step 2: Same as in Example 1; Step 3, same as in Example 1; Step 4: Based on Example 1, an intelligent temperature control membrane made of phase change material and an aerated gel insulation layer are further provided between the moisturizing breathable membrane and the anti-UV windproof net, and the intelligent temperature control membrane is arranged close to the moisturizing breathable membrane.

[0036] Example 4 Step 1, same as in Example 1; Step 2: Based on Example 1, the scion buds are placed in a -5°C to 0°C environment for 24 hours before grafting, and a 100 μM abscisic acid solution is sprayed simultaneously to induce the expression of antifreeze protein genes; Step 3, same as in Example 1; Step 4: Same as Example 1.

[0037] Comparative Example 1 A single interface (single slope on the sunny side) is adopted, the scion bud is a single wedge-shaped portion, and the rest is the same as in Example 1.

[0038] Comparative Example 2 Use common straps for fixing, and the rest is the same as in Example 1.

[0039] Comparative Example 3 A common protective net is used, and no moisture control group is provided, and the rest is the same as in Example 1.

[0040] Comparative Example 4 A double-layer protective structure is adopted, but no moisture control group is provided, and the rest is the same as in Example 1.

[0041] The callus differentiation cycle, grafting survival rate, interface colony count, UV shielding rate, effective healing window length and humidity fluctuation of Pinus sylvestris var. mongolica grafted onto Pinus bungeana of Examples 1 to 4 and Comparative Examples 1 to 4 were investigated, and the results are shown in Table 1.

[0042] Table 1 Data of Pinus sylvestris grafted onto Pinus bungeana As can be seen from Table 1, Example 1 uses dual interfaces + dual wedges + smart bands + moisture control groups, and its callus differentiation cycle is 15 days, which is 47% shorter than the traditional single interface (Comparative Example 1, 22 days). This is because the dual interfaces increase the contact area of ​​the cambium, and the moisture control group stabilizes the humidity to promote cell division. Example 2 adds pH-responsive microspheres on the basis of Example 1, and its callus differentiation cycle is 12 days. The precise release of sodium humate accelerates callus differentiation, so the callus differentiation cycle is shortened by 20% compared with Example 1. Comparative Example 1 uses a grafting method with a single interface and a single wedge, and its callus differentiation cycle is the longest. Because the contact area of ​​the cambium is small, the interface stress is concentrated and easy to crack.

[0043] It can also be seen from Table 1 that Example 3 adds an intelligent temperature control film and an aerated gel insulation layer on the basis of Example 1, and its grafting survival rate can reach 98%. Active temperature control is used to reduce temperature difference damage, and the survival rate is increased by 7.7% compared with Example 1; while Comparative Example 3 uses an ordinary protective net and no moisture control group, and its grafting survival rate is only 75%. This is because UV burns, excessive wind speed, and large humidity fluctuations lead to the death of the scion. Example 1 uses a photothermal responsive shape memory polymer strap, and its interface colony count is 80 CFU / cm 2 The nano silver antibacterial agent effectively inhibited low-temperature pathogens, compared with the comparative example 2 (using ordinary bandage, 120 CFU / cm 2 ) is reduced by 50%, because there is no sustained release of drugs in comparative example 2, the number of colonies is high, and it is easy to cause interface infection. The UV shielding rate of Examples 1 to 4 is ≥90%, and the UV windproof net effectively shields ultraviolet rays to protect the scion buds from light damage, while the UV shielding rate of the ordinary protective net used in comparative example 3 is only 50%, and the scion buds are easily burned by ultraviolet rays, and the survival rate decreases.

[0044] It can also be seen from Table 1 that Example 4 pre-treated the scion bud, and its effective healing window length was 42 days. Abscisic acid induced antifreeze protein to extend the low temperature adaptation period, which was 28% longer than Example 1 (effective healing window length 35 days); while the effective healing window length of Comparative Example 1 was only 23 days, due to the poor freezing resistance of the scion, the healing stagnation under low temperature environment. The humidity fluctuations of Examples 1 to 4 were all less than 2%, among which the humidity fluctuation of Example 2 was 1.5%, and the trehalose hydrogen bond grid stabilized the humidity, which further reduced the humidity fluctuation compared with Example 1 (2%); while the humidity fluctuations of Comparative Examples 3 and 4 were both ≥5%, without a control moisture mass or pH response mechanism, and the interface damage was easily caused by drying or condensation.

[0045] In summary, the present invention adopts a double-interface + double-wedge grafting method to directly increase the contact area formed, shorten the callus differentiation cycle, and increase the survival rate by 30% (70%→91%) compared with a single interface; the present invention adopts a photothermal responsive shape memory polymer bandage + humidity control group structure, which effectively reduces the number of interface colonies and reduces humidity fluctuations through drug sustained release and precise humidity control; the present invention also actively responds to high-cold temperature differences and low-temperature stress through temperature control membrane + scion pretreatment, thereby extending the effective healing window and further improving the survival rate of grafting.

[0046] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for high survival rate of Pinus sylvestris var. mongolica grafted with Pinus bungeana in high-altitude cold regions, characterized in that: include: Step 1: Open a double interface on the larch, the first interface is located on the sunny side and cuts an ascending slope, the second interface is located on the shady side and cuts a descending slope, and the first interface and the second interface are connected through an incision; Step 2: Select the top bud branch of Tibetan white pine as the scion bud, and cut a double wedge-shaped portion that fits the first interface, the second interface and the incision on three sides; Step 3, the double wedge-shaped parts of the scion bud are respectively pressed against the double interfaces of the rootstock, and mechanically adapted and fixed by using a photothermal responsive shape memory polymer band, wherein the photothermal responsive shape memory polymer band is provided with a penetration hole; Step 4: after grafting, a double-layer protective structure is constructed outside the scion bud, wherein the inner layer of the double-layer protective structure is a moisturizing breathable film, and the outer layer is an anti-UV windproof net; Wherein, a soaked moisture control mass is arranged in the moisture-retaining breathable membrane to maintain the air humidity at the interface not less than 60% within 20 days.

2. The high survival rate method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold regions as claimed in claim 1, characterized in that: The lengths of the first wedge-shaped portion and the second wedge-shaped portion of the double wedge-shaped portion are 2 cm and 4 cm respectively, and the thickness ratio of the connection between the first wedge-shaped portion and the second wedge-shaped portion is 1:

2.

3. The high survival rate method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold regions as claimed in claim 1, characterized in that: The photothermal responsive shape memory polymer bandage includes, from outside to inside, a polycaprolactone / carbon nanotube composite photothermal conversion layer, a first poly N-isopropylacrylamide modified thermosensitive hydrogel layer and a drug-loaded porous polylactic acid fiber layer, wherein the carbon nanotube content in the polycaprolactone / carbon nanotube composite photothermal conversion layer is 0.5-1.2wt%, the LCST of the first poly N-isopropylacrylamide modified thermosensitive hydrogel layer is 28°C, and the drug-loaded porous polylactic acid fiber layer is loaded with 10% by mass of nanosilver / de-earth composite antibacterial agent, 5% of indolebutyric acid and β-cyclodextrin. When the temperature of the inner layer is higher than 28°C, the first poly N-isopropylacrylamide modified thermosensitive hydrogel layer undergoes a volume phase change to promote the sustained release rate of the drug in the drug-loaded porous polylactic acid fiber layer.

4. The high survival rate method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold regions as claimed in claim 1, characterized in that: The outer layer of UV-resistant windproof net is woven with shape memory polyurethane fiber. When the ambient wind speed exceeds the wind speed threshold, the mesh aperture automatically shrinks by 40-60%. The inner layer of moisturizing and breathable membrane uses polyvinyl alcohol / polyethylene glycol blended polymer membrane as the basic skeleton, and is modified by glutaraldehyde cross-linking to form a three-dimensional grid structure. The inner layer of moisturizing and breathable membrane is embedded with thermosensitive hydrogel microcapsules. The LCST of the thermosensitive hydrogel microcapsules is 15°C. When the temperature is lower than 15°C, the thermosensitive hydrogel microcapsules release gibberellin A3.

5. The method for high survival rate of Pinus sylvestris var. mongolica grafted onto Pinus bungeana in high-cold areas as claimed in claim 4, characterized in that: The gibberellin A3 is wrapped by a second poly N-isopropylacrylamide modified hydrogel, and the second poly N-isopropylacrylamide modified hydrogel swells and releases gibberellin A3 at low temperatures to improve the low temperature stress resistance of the scion bud.

6. The high survival rate method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold regions as claimed in claim 4, characterized in that: The surface of the anti-UV windproof net is coated with a photochromic nano coating, which is composed of vanadium dioxide and tungsten oxide composite nanowires. When the ultraviolet intensity is greater than the ultraviolet intensity threshold, the refractive index of the coating is automatically lowered, reducing the light transmittance of the windproof net by 40-50%.

7. The high survival rate method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold regions as claimed in claim 1, characterized in that: The moisture control group includes, from the inside to the outside, a sodium polyacrylate water-absorbent resin compressed core with a thickness of 5:3:5, a spirally wound cotton wool fiber, and a polylactic acid porous membrane, wherein the water absorption rate of the sodium polyacrylate water-absorbent resin compressed core is 500-800 times, and the sodium polyacrylate water-absorbent resin compressed core releases bound water when the daytime temperature is >5°C, and recaptures condensed water in the polylactic acid porous membrane when the nighttime temperature is <0°C; the diameter of the cotton wool fiber is 10-15 μm, and the pore size of the polylactic acid porous membrane is 50-100 μm.

8. The method for high survival rate of Pinus sylvestris var. mongolica grafted onto Pinus bungeana in high-cold areas as claimed in claim 7, characterized in that: pH-responsive cellulose microspheres are pre-embedded in the spirally wound absorbent cotton fibers. The pH-responsive cellulose microspheres are loaded with 15% by mass of potassium humate and 5% by mass of trehalose. When the pH at the interface changes to 6.2-6.5 due to callus metabolism, the wall material of the pH-responsive cellulose microspheres dissolves to release potassium humate to promote callus cell differentiation. At the same time, trehalose and sodium polyacrylate water-absorbent resin compress the moisture in the core to form a hydrogen bond grid, thereby stably regulating the air humidity to be above 60%.

9. The high survival rate method of grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold regions as claimed in claim 1, characterized in that: An intelligent temperature control membrane made of phase change material and an air-filled gel insulation layer are also provided between the moisturizing breathable membrane and the anti-UV windproof net, and the intelligent temperature control membrane is arranged close to the moisturizing breathable membrane.

10. The high survival rate method for grafting Pinus sylvestris var. mongolica onto Pinus bungeana in high-cold regions as claimed in claim 1, characterized in that: The scion buds are placed in a -5°C to 0°C environment for acclimatization for 24 hours before grafting, and are simultaneously sprayed with an abscisic acid solution with a concentration of 50 to 100 μM to induce the expression of antifreeze protein genes.

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