A multi-point parrot tongue grafting method for white bark pine

Abstract

This invention relates to the field of Chinese white pine propagation technology, specifically disclosing a multi-point grafting method for Chinese white pine using the "sparrow tongue" technique. First, branches with plump terminal buds from the upper and middle parts of the Chinese white pine are selected as scions. The needles are treated and cut with specific positive and short cut surfaces. Next, slightly thicker lateral branches from the upper and middle parts of the rootstock are selected and treated to create matching mating surfaces. Finally, the scions are inserted and wrapped with PE film strips. Four to five scions are grafted onto one rootstock. This method, through precise scion and rootstock treatment and multi-point grafting, effectively improves the grafting survival rate, promotes the growth of grafted seedlings, and is beneficial for germplasm resource preservation and large-scale propagation, possessing significant application value in the field of Chinese white pine cultivation.

Description

Technical Field

[0001] This invention relates to the field of white pine propagation technology, and in particular to a multi-point grafting method for white pine using the sparrow tongue technique. Background Technology

[0002] White pine (scientific name: Pinus bungeana *Pinus bungeana* (Zucc. ex Endl.) is an evergreen tree belonging to the Pinaceae family and the *Pinus* genus. The white pine is a large evergreen tree, reaching up to 30 meters in height. Young trees have smooth, grayish-green bark, while mature trees have pale yellowish-brown bark that peels off in thin flakes or irregular scales, revealing a pale yellowish-green or pinkish-white inner bark, creating a mottled, scaly pattern. The branches spread, forming a broad crown. Leaves are in bundles of three, coarse and stiff, 5–10 cm long, with finely serrated edges, and a membranous sheath at the base. Male cones are ovoid or elliptical, mostly clustered in spikes at the base of new branches, flowering from April to May. Cones are usually solitary, initially erect then drooping, pale green before maturity, turning pale yellowish-brown when ripe, ovoid or conical-ovoid, maturing in October or November of the following year. Seeds are grayish-brown.

[0003] The Chinese white pine is an important ornamental and timber tree species unique to China, mainly distributed in the Xiaolongshan area of ​​Shanxi, Shaanxi, and Gansu provinces, with abundant ancient trees in the Beijing area. Its beautiful tree shape and unique bark color make it highly ornamental, and it is a traditional landscaping tree species, suitable for solitary planting, paired planting, grove planting, or as a street tree. Its wood is hard and fine-grained, with yellowish-brown heartwood and yellowish-white or yellowish-brown sapwood. The grain is straight, lustrous, and beautiful, making it suitable for construction, furniture, and stationery. Furthermore, the Chinese white pine is resistant to ozone, sulfur dioxide, and soot, playing a significant role in factory and urban greening.

[0004] The propagation of Chinese white pine is mainly through seed reproduction, but this method suffers from segregation of traits in offspring, making it difficult to maintain superior varietal characteristics. In recent years, the nation has placed unprecedented emphasis on the protection and preservation of germplasm resources and ancient trees. Asexual reproduction can better preserve the superior genes of ancient Chinese white pine trees and better maintain the excellent characteristics of new varieties, avoiding the adverse effects of seed reproduction. However, due to current technological limitations, the survival rate of cuttings in asexual reproduction is low, less than 10%, making grafting technology particularly important for Chinese white pine. However, traditional grafting methods also have low survival rates, limiting the large-scale promotion and application of Chinese white pine. In recent years, with the development of forestry technology, the application of grafting technology in the propagation of Chinese white pine has gradually increased, but improving the grafting survival rate remains a key technical challenge.

[0005] In response to the aforementioned technologies, the inventors believe that it is necessary to develop a grafting method for white pine that can significantly improve the grafting survival rate. Summary of the Invention

[0006] To address the technical deficiencies of existing technologies, this application provides a multi-point grafting method for white pine with a sparrow tongue-like grafting technique.

[0007] Firstly, this application provides a multi-point grafting method for white pine with a sparrow's tongue grafting technique, employing the following technical solution:

[0008] A multi-point grafting method for white pine with a sparrow's tongue technique includes the following steps:

[0009] S1: Select the terminal bud branches of white pine as scions, remove excess needles from the scions, leaving 4-6 bundles at the top, cover the needles with plastic wrap and leave the top exposed; process the scions using the three-cut method, the first cut is made below the terminal bud, peeling off the bark on one side of the scion to make a long cut, the second cut is made by peeling the bark on the side of the long cut into a bird's tongue shape to make a short cut, the long cut and the short cut form an acute angle and both reach the xylem; the third cut is to make a second cut to make the cut smooth and flat.

[0010] S2: Select a slightly thicker lateral branch from the middle of the rootstock, retain the terminal bud and needles of the lateral branch, and remove only the needles at the grafting point; make a horizontal cut from top to bottom on the lateral branch, with the cut being deep and reaching the pith; cut off the phloem on the cut to make a long cut surface that matches the long cut surface, and leave a tongue-shaped phloem that matches the short cut surface to make a short cut surface.

[0011] S3: Take a scion and insert it into the rootstock. Align the long cut surface of the rootstock with the long cut surface of the scion, and the short cut surface of the rootstock with the short cut surface of the scion. Wrap it with PE film strips. One rootstock can be grafted with 4 to 5 scions.

[0012] By employing the above technical solution, the innovation of this invention lies in removing most of the phloem from the rootstock's mating surface while retaining a portion of the phloem tissue, thereby reducing the amount of pine resin secreted from the rootstock wound. The three-cut method ensures a smooth and even incision, promoting callus formation. Furthermore, the innovative preservation of the rootstock's terminal bud and most of its needles provides nutrition to the scion without affecting the normal growth of lateral branches after grafting failure. Simultaneously, the precise treatment of the scion and rootstock ensures close contact, improving the grafting survival rate. Multi-point grafting fully utilizes rootstock nutrients, promoting seedling growth. This unique treatment method also ensures the stable inheritance of superior traits, facilitating large-scale propagation, improving germplasm resource utilization efficiency, and contributing to the large-scale cultivation and promotion of high-quality white pine seedlings.

[0013] Preferably, the white pine terminal bud branches in step S1 are one-year-old branches with plump terminal buds in the middle and upper part of the mother plant and a thickness of 0.4 to 0.5 cm.

[0014] By adopting the above technical solution, the selected branches grow vigorously and have sufficient nutrient reserves, which is conducive to growth and development after grafting. The scions in this thickness range not only have sufficient nutrient supply capacity, but also fit well with the rootstock.

[0015] Preferably, the time for collecting the spikelets in step S1 is from March 21 to March 31 or from August 10 to August 19.

[0016] By adopting the above technical solution, from March 21st to March 31st, the mother trees of the Chinese white pine, having accumulated nutrients during winter, begin to flow sap and their physiological activity gradually increases. At this time, the scions collected exhibit vigorous cell division and are rich in nutrients, which is beneficial for healing and growth after grafting. From August 10th to August 19th, the new shoots of the Chinese white pine have basically stopped growing, the branches have sufficient nutrients, and environmental conditions such as temperature and humidity are relatively suitable, resulting in faster wound healing after grafting and ensuring a certain grafting survival rate.

[0017] Preferably, the rootstock is a 6-year-old container seedling of Pinus bungeana from a half-sib family, with a seedling height of 50-70 cm.

[0018] By adopting the above technical solutions, the plants exhibit vigorous growth, which is beneficial for subsequent grafting operations and nutrient supply, while also providing a good foundation for the growth of the scions.

[0019] Preferably, the rootstock needs to be inoculated with mycorrhizal soil one month before grafting. The mycorrhizal inoculation treatment involves evenly covering the rootstock roots with topsoil from the root system of white pine on the surface of the container. The topsoil is selected from the topsoil around the root system of perennial white pine forests.

[0020] By employing the above-mentioned technical solution, mycorrhizae, a symbiotic relationship between soil fungi and plant roots, play a special and crucial role in the growth of Chinese white pine. They form a symbiotic relationship with the pine root system, helping the plant better absorb nutrients and water, and enhancing its resistance to adverse conditions. Mycorrhizal inoculation treatment allows seedlings to quickly replenish their mycorrhizae, fully preparing them for the upcoming grafting process and post-grafting growth, thus helping to improve the grafting survival rate and the overall growth quality of the grafted seedlings.

[0021] Preferably, the long sliced ​​surface is 5 cm long, the cut surface near the apical bud of the long sliced ​​surface is a smooth semi-circular groove, the short sliced ​​surface has a bird's tongue-shaped cut surface of 0.5 cm long, and the long sliced ​​surface and the short sliced ​​surface form an acute angle of 30 to 45 degrees.

[0022] By adopting the above technical solutions, the scion and rootstock can be treated in a targeted manner, which can expand the contact area between the scion and rootstock. At the same time, the 30-45 degree acute angle makes it easier to fit tightly, which helps to improve the grafting survival rate.

[0023] Preferably, the long cut surface of the mating surface is 4.5 cm long, and the short cut surface of the mating surface is 0.5 cm long.

[0024] By adopting the above technical solution, the cambium of the rootstock can be in close contact with the scion, while maintaining sufficient phloem to transport nutrients to the scion, thereby improving the grafting survival rate.

[0025] Preferably, after grafting is completed in step S3, the entire grafted seedling is covered with a black plastic bag and the bag opening is sealed with soil, and a 50% shade net is erected.

[0026] By adopting the above technical solutions, a stable high-temperature, high-humidity, and low-light environment can be created for the seedlings after grafting: black plastic bags can reduce water evaporation, maintain humidity at the graft union, and promote callus formation; shading nets with a 50% shading rate can prevent direct sunlight from causing the scion to lose water through transpiration, while providing suitable diffused light to maintain the seedlings' weak photosynthesis. The combination of the two can significantly improve the grafting survival rate and provide ideal microenvironmental conditions for the initial growth of white pine seedlings.

[0027] Preferably, the multi-point grafting method for white pine also includes post-grafting management, which includes water and fertilizer management, rootstock pruning, soil loosening and weeding, pest and disease control, and removal of shade netting.

[0028] By adopting the above technical solutions, the growth of grafted white pine seedlings can be systematically guaranteed. Water and fertilizer management promotes healing and nutrient supply, staged pruning of the rootstock guides the independent growth of the scion, loosening the soil and weeding optimizes the root environment, biological and chemical control measures are combined to prevent and control pests and diseases, and the removal of shade nets in winter enhances light exposure. All these aspects work together to improve the survival rate and seedling vigor.

[0029] Preferably, the rootstock pruning is carried out in three stages. The first pruning is done 45 days after grafting, removing the plastic bag and the scion's plastic wrap. The second pruning is done 60 days after grafting, cutting off excess branches of the rootstock and leaving only branches that do not compete with the surviving scion. The third pruning is done one year after grafting, retaining the branches of the surviving scion and removing all other branches.

[0030] By adopting the above technical solution, the growth structure of grafted seedlings can be optimized step by step. The first step is to remove the plastic bag and cling film 45 days after grafting, simultaneously pruning the rootstock and retaining the surviving scion to help it adapt to the external environment and remove constraints. The second step is to prune excess competing branches of the rootstock 60 days later, retaining auxiliary branches that provide nutrients to balance the nutrient distribution between the scion and rootstock. The third step is to leave only the surviving scion branches one year after grafting, completely completing the transition from rootstock dependence to independent growth. This phased pruning method avoids the growth stress caused by a single pruning, gradually weakening the rootstock's dominance and guiding the scion to dominate growth, significantly improving the survival rate and growth stability of grafted seedlings.

[0031] In summary, this application has the following beneficial effects:

[0032] 1. This application innovatively uses a "three-cut method" to process the scion. Specifically, it involves precisely cutting to create a long cut surface of a specific size and angle, and a short cut surface shaped like a bird's tongue. A third cut is then used to refine the cut, ensuring it is smooth and flat. By using a reasonable acute angle and a semi-circular groove-shaped cut surface, the contact area between the scion and the rootstock is maximized, allowing their cambium layers to fit tightly together. This creates favorable conditions for nutrient transport and callus formation. At the same time, the smooth and flat cut effectively reduces pine resin secretion from the rootstock wound, preventing pine resin accumulation from hindering healing. This fundamentally solves the problems of slow healing and low survival rate caused by traditional rough cuts, laying a core foundation for successful grafting.

[0033] 2. The innovative design of retaining the rootstock's terminal bud and most of its needles breaks away from the traditional grafting logic of extensive leaf removal, fully utilizing the rootstock's photosynthetic function to ensure a continuous supply of nutrients. During the healing period of a white pine graft, the scion cannot independently complete sufficient photosynthesis, while the retained rootstock terminal bud and needles can maintain weak but crucial photosynthetic activity, continuously synthesizing nutrients to provide the necessary energy and nutrients for scion healing. This effectively avoids the risk of scion withering due to nutrient supply interruption in traditional leaf-removal grafting. Furthermore, this design has strong fault tolerance; even if some scions fail to graft, the retained rootstock terminal buds and lateral branches can still grow normally, avoiding the waste of the entire rootstock resource, reducing grafting risk, and achieving efficient utilization of germplasm resources.

[0034] 3. Multi-point grafting technology has achieved a major breakthrough in propagation efficiency. By grafting 4-5 scions onto one rootstock, the nutrient supply potential of the rootstock is fully explored. Selecting vigorous, nutrient-rich, and mature rootstocks, which inherently possess the ability to support the growth of multiple scions, multi-point grafting fully releases this potential, breaking the limitations of low propagation efficiency in the traditional single-rootstock, single-scion model. Multiple scions simultaneously obtain nutrients from the rootstock, significantly increasing the propagation yield of a single rootstock while ensuring the nutritional supply of each scion. Furthermore, the selection of robust branches from high-quality mother plants for scions, combined with precise grafting between scions and rootstocks, ensures the stable inheritance of superior traits from the mother plant, avoiding the trait segregation problem in seed propagation. This provides core support for the large-scale propagation of high-quality seedlings and significantly improves the utilization rate of germplasm resources.

[0035] 4. Through the synergistic application of a series of supporting technologies and three core innovations, the overall effect has been further amplified, constructing a comprehensive growth guarantee system. Pre-grafting mycorrhizal inoculation treatment enhances the rootstock's nutrient absorption capacity by introducing symbiotic fungi, providing a robust growth foundation for subsequent grafting. Post-grafting environmental control utilizes black plastic bags and 50% shade netting to create a high-temperature, high-humidity, low-light environment, reducing water evaporation and avoiding strong light stress, thus creating optimal conditions for callus formation. Post-grafting refined management, from water and fertilizer supply and phased rootstock pruning to pest and disease control, addresses key issues such as water, nutrients, and light during the healing period. Furthermore, gradual rootstock pruning guides the scion to smoothly transition to independent growth, effectively mitigating growth stress risks. This, combined with the core innovations, has resulted in a dual improvement in survival rate and seedling robustness. Detailed Implementation

[0036] The present application will be further described in detail below with reference to the embodiments.

[0037] Example 1

[0038] This embodiment involves the selection and treatment of rootstock. In this embodiment, the rootstock is a 6-year-old container seedling of Pinus bungeana, a half-sib family. This 6-year-old container seedling was carefully cultivated from a 3-year-old seedling over 3 years. Strict requirements were placed on its growth status during selection; the plant height needed to be maintained between 50 and 70 cm. Plants within this height range exhibit vigorous growth, which is beneficial for subsequent grafting operations and nutrient supply. Furthermore, healthy plants free from pests and diseases were given priority as rootstock, as healthy rootstock provides a good foundation for the scion's growth and avoids the impact of rootstock diseases and pests on graft survival rate and later growth of the grafted seedling.

[0039] One month before grafting, the rootstock needs to be inoculated with mycorrhizae. Mycorrhizae are symbiotic organisms of soil fungi and plant roots, playing a special and crucial role in the growth of Chinese white pine. They form a symbiotic relationship with the root system, helping the plant better absorb nutrients and water, and enhancing its resistance to adverse conditions. The specific method for this mycorrhizae inoculation treatment is to select topsoil around the root system of a perennial Chinese white pine forest, taking a 3 cm layer. This topsoil is rich in special mycorrhizae necessary for the growth of Chinese white pine. Currently, there is no effective technology to extract these special mycorrhizae; most commercially available mycorrhizae preparations are for agricultural plants and are not suitable for Chinese white pine. The collected topsoil is then evenly spread around the rootstock roots on the surface of the container. This allows the seedling to quickly replenish its mycorrhizae, preparing it thoroughly for the upcoming grafting process and post-grafting growth, thus helping to improve the grafting survival rate and the overall growth quality of the grafted seedling.

[0040] Example 2

[0041] This embodiment involves the selection and collection of scions.

[0042] Determination of scion source: The selection of scions in this embodiment follows clear standards. Priority is given to collecting superior clones of Chinese white pine recognized by the national or provincial / municipal forest variety approval committees, new varieties recognized by the state, or ancient Chinese white pine trees. Scions from these sources possess excellent genetic traits, ensuring that the grafted Chinese white pine inherits and exhibits superior characteristics, such as better ornamental value and stronger adaptability.

[0043] Specific requirements for scion collection: When collecting scions, suitable branches should be selected from specific parts of the mother plant. Specifically, branches with plump terminal buds should be collected from the upper-middle part of the mother plant. These branches are vigorous and have sufficient nutrient reserves, which is beneficial to post-grafting growth and development. The collected scions should be one-year-old branches with a diameter of 0.4-0.5 cm. Scions in this diameter range have sufficient nutrient supply capacity and can fit well with the rootstock. In terms of length, scions with a length of 12 cm are preferred. This length ensures sufficient growth tissue while facilitating handling during the grafting process, which helps to improve the grafting success rate and the growth effect of the grafted seedling.

[0044] After collection, the scions need to be properly stored temporarily to maintain their viability. Specifically, place the scions in a small bucket of clean water, ensuring the cut end of the scion is facing down, and submerge them in 1-2 cm of water. This allows the cut end to directly contact the water, replenishing the moisture lost during collection and preventing the scions from drying out, thus maintaining cell activity. For ease of management and identification, scions from the same clone are usually bundled together, with each bundle containing 30-50 scions. A label should be attached, and the label should contain detailed information about the scion, including the collection time, location, collector, and variety. This information is crucial for subsequent grafting operations and the management and research of grafted seedlings.

[0045] In addition to soaking the cut ends in water, water can be sprayed onto the tips of the branches to further maintain the moisture of the scions. This creates a moist environment on the surface of the scions, reducing water evaporation and better preserving their freshness. It is important to emphasize that the key step in the entire process is to graft immediately after harvesting. As the scion's vigor gradually decreases over time, timely grafting maximizes the utilization of the scion's activity and improves the grafting success rate.

[0046] Timing of scion collection: In northern regions, especially Beijing, there is a specific optimal time to collect pine scions. The best time is from March 21st to March 31st. During this period, the mother pine trees have accumulated nutrients over winter, sap begins to flow, and physiological activity gradually increases. Scions collected at this time exhibit vigorous cell division and are rich in nutrients, which is beneficial for healing and growth after grafting.

[0047] In addition, mid-August is also a viable collection period, generally from August 10th to August 19th. At this time, the new shoots of the white pine have basically stopped growing, the branches have sufficient nutrients, and the environmental conditions such as temperature and humidity are relatively suitable, resulting in faster wound healing after grafting and ensuring a certain grafting survival rate. However, compared to spring, the growth cycle after autumn grafting is shorter, requiring more attention to post-grafting care and management.

[0048] Example 3

[0049] This embodiment provides a multi-point grafting method for white pine with a sparrow's tongue grafting technique, including the following steps:

[0050] (1) Scion treatment

[0051] The treatment of the scion is a crucial step in the grafting process, directly affecting the success rate and subsequent growth. The specific procedures are as follows:

[0052] Needle treatment: Carefully remove excess needles following their natural growth direction. This operation requires extreme caution to avoid damaging the phloem. The phloem plays a crucial role in nutrient transport in plants; damage can impair nutrient exchange between the scion and rootstock, thus reducing grafting success rate. After treatment, retain only the top 4-6 clusters of needles. These retained needles can perform photosynthesis, providing the scion with necessary energy and nutrients, which is beneficial for post-grafting growth. Then, wrap the needles with plastic wrap, starting from the bottom and wrapping upwards, stopping 2.5 cm from the top of the needle. Leave the top 2.5 cm of needles unwrapped. This reduces transpiration, maintains humidity around the needles, minimizes water evaporation, and allows the top needles to receive normal sunlight, maintaining photosynthesis.

[0053] Cutting the scion: At a point 1.5 cm below the terminal bud, use a sharp grafting knife to cut the scion. This invention employs a three-cut method for scion treatment. The first cut involves shaping one side of the scion into a 5 cm long surface, with the portion near the terminal bud shaped into a smooth, semi-circular groove. This shape increases the contact area with the rootstock, facilitating nutrient exchange and callus formation. The second cut transforms the long surface into a 0.5 cm long, tongue-shaped short surface, creating an acute angle between the long and short surfaces, preferably 30°–45°. Both the long and short surfaces must be precisely cut to the xylem. The xylem is the primary channel for water and mineral transport in plants; cutting to the xylem ensures effective water and nutrient transfer between the scion and rootstock. The third cut is a final cut back to ensure better adhesion between the scion and rootstock, and to guarantee a smooth and even cut on the scion, resulting in neat cell division and callus formation within 3 days.

[0054] After a series of treatments, the scion length is ultimately maintained at around 10 centimeters. The treated scions need to be immediately placed in a constant temperature incubator for storage. The incubator can provide a relatively stable and suitable temperature environment for the scions, maintain their activity, and prevent them from losing vitality due to changes in the external environment, ready for the next grafting step.

[0055] (2) Rootstock treatment

[0056] The treatment of the rootstock is also crucial for successful grafting. The following is a detailed procedure:

[0057] Branch selection: Select branches from the rootstock that match the conditions of the scion, generally choosing the lower part of one-year-old branches or the upper part of two-year-old branches. These lateral branches have strong growth vigor and ample nutrient supply, which is beneficial to the growth of the scion after grafting. Moreover, the selected rootstock lateral branches should be slightly thicker than the scion, so that they can better wrap around the scion during grafting, providing stable support and a sufficient source of nutrients for the scion.

[0058] Needle removal: Retain the terminal bud of the rootstock, and at the selected grafting point, remove needles within a 5 cm radius of the branch from top to bottom. This facilitates better adhesion between the rootstock and the scion's long cut surfaces. Additionally, retain the needles at the branch tip. Except for the area where the scion and rootstock need to adhere, retain needles elsewhere on the branch. The purpose is for the rootstock to utilize the needles for photosynthesis. The more needles the rootstock has, the more photosynthetic products it accumulates, the more vigorous its vitality, and the more endogenous hormones it can produce, promoting adhesion between the rootstock and scion and improving the grafting survival rate.

[0059] Cutting Preparation: Use a two-cut method to treat the rootstock. The first cut is made with a grafting knife, making a horizontal cut from top to bottom on the selected lateral branch. Maintain a smooth cut with moderate and even pressure, ensuring a depth of approximately 0.5 cm, until reaching the pith of the lateral branch. The cut length should be 5 cm. The pith is the central part of the plant stem, responsible for storing and transporting nutrients; cutting to the pith helps the scion better absorb nutrients from the rootstock. The second cut is made 4.5 cm from the top, below the already cut phloem. Remove 4.5 cm of phloem, exposing the cambium as the long cut surface for bonding, leaving a 0.5 cm lard-shaped section of phloem as the short cut surface. The long cut surface is for bonding with the long cut surface of the scion; the short cut surface is for bonding with the short cut surface of the scion.

[0060] Since white pine naturally secretes resin when cut, choosing a smaller incision can effectively reduce the amount of resin secreted, thereby creating a more favorable environment for wound healing and reducing healing obstacles caused by excessive oil exudation.

[0061] Meanwhile, precisely positioning the incisions of the scion and rootstock at the pith cambium is a key technical point for improving grafting success. The core advantages of this technique are twofold: firstly, the strong regenerative capacity of the parenchyma cells in the pith compensates for the relatively insufficient activity of the coniferous cambium, providing ample energy for tissue repair; secondly, it cleverly avoids the resin ducts within the conifer—structures that readily secrete large amounts of oil when stimulated by external factors. Precise incision positioning reduces stimulation of the resin ducts, significantly lowering the risk of the graft union being blocked by oil, accelerating the reconstruction of vascular tissue between the rootstock and scion, and ultimately effectively improving the grafting survival rate.

[0062] Furthermore, this invention innovates the rootstock treatment method by preserving the terminal bud and most of the needles of the rootstock, removing only those needles that affect the adhesion between the rootstock and scion. This is completely different from the conventional grafting method of removing the terminal bud and most of the needles. This rootstock treatment method provides sufficient energy for the formation of callus tissue and the connection of the vascular bundles between the rootstock and scion, thus improving the grafting survival rate. If the needles of the rootstock are removed too early or too much, the rootstock will not only fail to provide nutrients to the scion, but will also consume the limited nutrients stored in the root system and trunk, leading to nutrient competition at the grafting interface, hindering the healing process, and ultimately causing grafting failure. Preserving sufficient rootstock needles also maintains normal transpiration, ensuring that water and inorganic salts are continuously transported upwards to the grafting site. This not only provides the necessary water for the cell activity of the rootstock and scion, but also creates a moist microenvironment for the healing process, preventing tissue drying. At the same time, continuous water flow also helps transport hormones such as cytokinins produced by the roots to the wound site, promoting healing.

[0063] In addition, this application preserves the rootstock's future growth space by retaining the terminal bud and most of the needles. Even if the scion fails, it will not affect the normal growth of the rootstock, thus protecting the rootstock itself and providing a foundation for subsequent multi-point grafting.

[0064] (3) Grafting process

[0065] The grafting process requires precise operation to ensure a close connection between the scion and the rootstock, laying a good foundation for the growth of the grafted seedling.

[0066] Grafting Procedure: Remove the treated scion from the incubator and quickly insert it into the prepared phloem of the rootstock. During insertion, pay special attention to ensuring the cambium layer of the long cut surface of the scion is tightly aligned with the long cut surface of the scion, making them as close together as possible. The cambium layer is crucial for cell division, wound healing, and new tissue growth in plants; ensuring cambium alignment improves the success rate of grafting. Simultaneously, press the 0.5 cm of the tongue-shaped phloem layer of the short cut surface of the rootstock firmly against the short cut surface of the scion, ensuring no gaps between them to facilitate nutrient transfer and callus formation.

[0067] Secure Bandaging: After grafting, wrap the graft union with layers of PE film strips. Ensure the PE film strips fit tightly without any gaps to prevent moisture, air, and microorganisms from entering and affecting healing. The binding strips are typically made of 0.04 mm thick PE film, cut into strips 2.5 cm wide and 35 cm long. This size provides sufficient strength to secure the scion and rootstock while maintaining a degree of flexibility to avoid excessive pressure on the graft union and hindering growth.

[0068] Multiple grafting: To more quickly showcase the superior qualities of the white pine and fully express its excellent genes, multiple grafting is employed. This involves selecting multiple suitable branches on a single rootstock for grafting; typically, one rootstock can support four to five scions. This method fully utilizes the rootstock's nutrients, increases the chances of successful grafting, and allows the grafted seedlings to exhibit the superior characteristics of the white pine more rapidly.

[0069] Moisturizing and Shading: After grafting, creating a suitable growing environment for the grafted seedling is crucial. Cover the entire seedling with a large black plastic bag and secure the bottom with soil. This creates a relatively enclosed and humid microenvironment, reducing water evaporation and maintaining a moisture balance between the scion and rootstock, which is beneficial for healing at the graft union. Simultaneously, erect a shade net over the seedling, ensuring the net provides approximately 50% shading. Appropriate shading prevents the seedling from receiving excessive direct sunlight, avoiding overheating that could lead to excessive water evaporation and tissue damage, and providing a mild and suitable light environment for the seedling's growth.

[0070] Example 4

[0071] After grafting is completed according to the grafting method in Example 3, post-grafting management is still required, as follows:

[0072] 1. Water and fertilizer management

[0073] Immediately after grafting, make two holes 15 cm deep, running north-south, about 20 cm from the base of the grafted seedling. Prepare a solution containing 8 g of 32% carbendazim, 10 g of kasugamycin, 20 g of amino oligosaccharide, and 2.5 ml of indolenaphthaleneacetic acid, diluted in 15 kg of water. Pour 25 ml of this solution into each hole to promote graft healing and improve root nutrition. Water thoroughly afterward, ensuring the soil is dry to the touch. Apply slow-release fertilizer 14 days after grafting. Generally, use 1 gram of Green Leopard controlled-release fertilizer per grafted seedling. To use, gently make a circular cut 5 cm deep, 15 cm from the base of the grafted seedling trunk with a sickle. Place 1 gram of slow-release fertilizer in the shallow trench, gently cover with soil, and then proceed with normal care and watering.

[0074] 2. Cutting the anvil (cutting the anvil should be done in 3 stages)

[0075] The first pruning of the rootstock should be done approximately 45 days after grafting. Remove the plastic bag and the cling film binding the scion, and prune the rootstock at the same time. First, observe the survival rate of the grafted seedling. Use a brush to apply a 0.05 mg / 1 kg solution of brassinolide evenly to the graft union to promote growth. If survival is confirmed, remove the upper part of the rootstock from the grafted scion, leaving only the successfully grafted scion.

[0076] The second pruning is done 60 days after grafting. Many branches in the rootstock can be pruned, leaving only some rootstock branches that do not compete with the grafted branches. These branches will serve as nutrient providers for the pine roots and will be retained for one year.

[0077] The third pruning is done a year later. Except for the grafted branches that have survived, all other branches are gradually pruned. First, observe the growth of the scion. The principle is to first remove the terminal buds of the vigorous branches of the rootstock, keeping the branches and needles. Then, every month, gradually remove some branches until all the rootstock branches are removed.

[0078] 3. Loose soil and weeding

[0079] After grafting, the white pine seedlings need frequent soil loosening, and weeding should be done at a depth of about 3 cm. Generally, soil loosening should be done after watering in spring when the soil is green again, and the soil depth should be about 5 cm. Throughout the year, the principle of watering when the soil is dry to the touch should be maintained, and the soil should be loosened frequently to retain moisture.

[0080] 4. Pest and disease control

[0081] After grafting, it is important to pay attention to integrated pest management. In spring, biological control methods should be used, such as releasing ladybugs to control pine aphids. In spring and summer, difenoconazole should be sprayed to prevent pine needle blight. In autumn, water control should be checked to prevent dieback, which can weaken the tree the following year.

[0082] 5. Remove the shade netting

[0083] The shade netting can be removed in time when winter arrives to increase light exposure and ensure the plant's healthy growth in the coming year.

[0084] To verify the effectiveness of the multi-point grafting method for white pine of the present invention in practical applications, the following application examples and comparative examples are set up.

[0085] Application Example 1

[0086] Material Selection and Preparation: Following the rootstock selection method in Example 1, three-year-old seedlings of Pinus bungeana from half-sib families were selected. After three years of planting, these seedlings were used as six-year-old container seedlings for rootstock. The seedlings were 50-70 cm tall and free from pests and diseases. One month before grafting, mycorrhizal inoculation was performed on the rootstock using 3 cm of topsoil around the roots of perennial Pinus bungeana trees. Following the scion selection method in Example 2, superior clones of Pinus bungeana recognized by the state were selected. On March 25th, one-year-old scions with plump terminal buds, a diameter of 0.4-0.5 cm, and a length of 12 cm were collected from the upper part of the mother plant.

[0087] Strictly follow the grafting steps. Remove excess needles from the scion along the direction of needle growth, retaining 6-8 bundles of needles at the top and wrapping them with plastic wrap, leaving the top 2.5 cm of needles exposed. Use the three-cut method to treat the scion. The first cut is to make a 5 cm long cut on one side of the scion's epidermis, shaping the long cut near the terminal bud into a smooth, semi-circular groove. The second cut is to make a 0.5 cm short cut in the shape of a bird's tongue, forming an acute angle between the long and short cuts and reaching the xylem. The third cut is to smooth the incision. After treatment, the scion should be 10 cm long and placed in a constant temperature incubator.

[0088] Select a lateral branch slightly thicker than the scion from the upper part of the rootstock, retaining the terminal bud and removing the needles from the part of the lateral branch that will be in contact with the scion. Make a 5 cm long incision as required, removing 4.5 cm of the phloem to expose the cambium as the long cut surface for bonding, and retaining 0.5 cm of the tongue-shaped phloem as the short cut surface for bonding. Remove the scion from the incubator and insert it into the phloem of the rootstock, aligning the cambium of the long cut surface with the long cut surface of the scion, and pressing the phloem of the short cut surface with the short cut surface of the scion. Secure it tightly with layers of PE film strips, 0.04 mm thick, 2.5 cm wide, and 35 cm long. Graft 4-5 scions onto one rootstock. After completion, cover the entire grafted seedling with an extra-large black plastic bag, securing the bag opening with soil, and erect a shade net with a shading rate of approximately 50%.

[0089] Follow the above-described post-grafting management methods to manage the grafted seedlings after grafting.

[0090] In this application example, a total of 297 plants were grafted from March 24 to March 28, 2024, with 281 plants surviving, achieving a survival rate of 95%.

[0091] Application Example 2

[0092] The selection and preparation of materials, grafting operations, and post-grafting management methods in this application example are basically the same as those in application example 1. The difference between this application example and application example 1 is that the scion selection time in this comparative example is August 19, 2023.

[0093] In this application example, a total of 138 plants were grafted, and 122 survived. The grafting survival rate was 88.4%.

[0094] Based on application example 1, set up application comparison examples 1-2.

[0095] Application Comparative Example 1 (Rootstock Treatment with 2 Cuts)

[0096] The material selection and preparation, as well as the post-grafting management methods, are the same as in Application Example 1. The difference between this application example and Application Example 1 is that this application example uses the two-cut method to treat the scion.

[0097] In this comparative study, a total of 150 plants were grafted, with 97 surviving, resulting in a survival rate of 64.7%.

[0098] Application Comparative Example 2

[0099] The material selection, preparation, and post-grafting management methods for this comparative example are the same as those for Application Example 1. The difference between this comparative example and Application Example 1 is that 3.5 cm of phloem is retained as the short cut surface for bonding when the rootstock is treated in this comparative example.

[0100] In this comparative study, a total of 50 plants were grafted, with 29 surviving, resulting in a survival rate of 58%.

[0101] Application Comparative Example 3

[0102] The material selection, preparation, and post-grafting management methods for this comparative example are the same as those for Application Example 1. The difference between this comparative example and Application Example 1 is that the phloem is not retained as the short cut surface for bonding when the rootstock is treated in this comparative example.

[0103] In this comparative study, a total of 50 plants were grafted, with 8 surviving, resulting in a survival rate of 16%.

[0104] Application Comparative Example 4

[0105] The selection and preparation of materials for this comparative example, as well as the post-grafting management methods, are the same as those in Application Example 1. The difference between this comparative example and Application Example 1 is that, in this comparative example, the terminal bud is removed during rootstock treatment, leaving only 8-12 bundles of needles at the top of the rootstock, while all other needles are removed.

[0106] In this comparative study, a total of 50 grafted plants were performed, with 23 surviving, resulting in a survival rate of 46%.

[0107] In addition, record the growth of the lateral branches corresponding to the scions that failed to survive.

[0108] Application Comparative Example 5

[0109] The material selection and preparation, as well as the post-grafting management methods, are the same as in Application Example 1. The difference between this comparative example and Application Example 1 is that mycorrhizal soil is not used for the rootstock in this comparative example.

[0110] In this comparative study, a total of 50 grafted plants were performed, with 38 surviving, resulting in a survival rate of 76%.

[0111] Application Comparative Example 6

[0112] The material selection and preparation, as well as the post-grafting management methods, are the same as in Application Example 1. The difference between this application example and Application Example 1 is that the grafting method used in this application example is the conventional bark grafting method.

[0113] The specific procedure is as follows: Make a vertical downward cut of 3-4 cm at the top of the rootstock, shape the lower end of the scion into a wedge shape, insert it into the cut in the rootstock, align the cambium layers on one side, and bind it tightly with a plastic strip. Using the traditional single-grafting method, one scion is grafted onto each rootstock.

[0114] In this comparative application example, a total of 50 plants were grafted, and 9 plants survived, with a survival rate of 18%.

[0115] Application Comparative Example 7

[0116] The material selection, preparation, and post-grafting management methods for this comparative example are basically the same as those for Application Example 1. The difference between this comparative example and Application Example 1 is that the rootstock in this comparative example does not involve removing 4.5 cm of phloem to expose the cambium. Instead, the phloem is used as the long cut surface for bonding, and another 0.5 cm of tongue-shaped phloem is cut out as the short cut surface for bonding. Other grafting operations are the same as those in Application Example 1.

[0117] In this comparative application example, a total of 297 plants were grafted, with 61 plants surviving, resulting in a survival rate of 20.5%.

[0118] A detailed comparative analysis of the survival rates of grafted seedlings cultivated in the above application examples and comparative application examples reveals that the multi-point grafting method proposed in this invention exhibits significant advantages, substantially improving the survival rate of grafted white pine. Specific data shows that, under the same planting and maintenance conditions, the survival rate of grafted seedlings cultivated using the multi-point grafting method of this invention is more than 70% higher than that of traditional grafting methods.

[0119] The above application examples and comparative studies of grafted seedling survival rates demonstrate that the multi-point grafting method of this invention can significantly improve the survival rate of grafted white pine. Furthermore, the survival rate of spring grafting using this method is slightly higher than that of summer grafting. This may be because as spring temperatures gradually rise, the growth vitality of the white pine plants gradually increases, and cambium cell division becomes more active, which is more conducive to the healing between the scion and rootstock, thereby improving the grafting survival rate.

[0120] From a broader perspective, the application of the multi-point grafting method of this invention has profound significance for the preservation and utilization of Chinese white pine germplasm resources. It ensures the stable inheritance of the characteristics of superior Chinese white pine varieties, avoiding the loss of germplasm resources due to natural factors or limitations of traditional propagation methods. Simultaneously, this grafting technology also plays an important role in the preservation and development of ancient trees. By transferring the superior genes of ancient trees to new plants through grafting, it not only helps protect rare ancient tree resources but also further explores their potential economic and cultural value, providing strong support for the development of related industries.

[0121] In summary, the multi-point grafting technique for white pine provided by this invention, with its outstanding performance in improving grafting survival rate and enhancing plant adaptability, can be considered the best technical solution in the field of white pine grafting, opening up a broader prospect for the planting, propagation and sustainable development of white pine and related industries.

[0122] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for multi-point grafting of white pine with a sparrow's tongue technique, characterized in that, Includes the following steps: S1: Select plump terminal bud branches from the upper part of the white pine as scions. Remove excess needles from the scion, leaving 4-6 bundles at the top. Wrap the needles with plastic wrap, leaving the top exposed. Use the three-cut method to treat the scion. The first cut is made below the terminal bud, peeling off the bark on one side of the scion to make a long cut. The second cut is made by peeling the bark on the side of the long cut into a bird's tongue shape to make a short cut. The long cut and the short cut form an acute angle and both reach the xylem. The third cut is to make a smooth and flat cut. The terminal bud branch is a one-year-old branch with a plump terminal bud and a thickness of 0.4 to 0.5 cm from the middle and upper part of the mother plant; the long cut surface is 5 cm long, and the cut surface near the terminal bud is a smooth semi-circular groove; the short cut surface has a bird's tongue-shaped cut surface of 0.5 cm long, and the long cut surface and the short cut surface form an acute angle of 30 to 45 degrees. S2: Select a slightly thicker lateral branch from the upper part of the rootstock, retaining the terminal bud and needles of the lateral branch, and removing only the needles at the grafting point; use a two-cut method to treat the rootstock. The first cut is to make a horizontal cut from top to bottom on the selected lateral branch with a grafting knife. When operating, keep the cut smooth, with moderate and even pressure, and ensure that the cut depth reaches about 0.5 cm, until it reaches the pith of the lateral branch. The cut length is 5 cm. The pith is the central part of the plant stem, which has the function of storing and transporting nutrients. Cutting to the pith helps the scion to better obtain nutrients from the rootstock. The second cut is to make a cut downwards at 4.5 cm from the top, at the position of the already cut phloem, removing 4.5 cm of phloem to expose the cambium as the long cut surface for bonding, leaving a 0.5 cm tongue-shaped phloem as the short cut surface for bonding. The rootstock is a 6-year-old seedling of Pinus bungeana from a half-sib family, with a height of 50-70 cm. One month before grafting, the rootstock needs to be inoculated with mycorrhizal soil. The mycorrhizal inoculation treatment involves evenly covering the root base of the rootstock around the container with topsoil from the Pinus bungeana root system. The topsoil is selected from the topsoil around the root system in a perennial Pinus bungeana forest. S3: Take a scion and insert it into the rootstock. Align the long cut surface of the rootstock with the long cut surface of the scion, and the short cut surface of the rootstock with the short cut surface of the scion. Wrap it with PE film strips. One rootstock can be grafted with 4 to 5 scions.

2. The multi-point grafting method for white pine according to claim 1, characterized in that... At: The collection time for the scions in step S1 is from March 21 to March 31 or from August 10 to August 19.

3. The multi-point grafting method for white pine according to claim 1, characterized in that: After grafting is completed in step S3, cover the entire grafted seedling with a black plastic bag and seal the bag opening with soil, then install a 50% shade net.

4. The multi-point grafting method for white pine according to claim 3, characterized in that: The multi-point grafting method for white pine also includes post-grafting management, which includes water and fertilizer management, rootstock pruning, soil loosening and weeding, pest and disease control, and removal of shade netting.

5. The multi-point grafting method for white pine according to claim 4, characterized in that: The rootstock pruning is carried out in three stages. The first pruning is done 45 days after grafting, removing the plastic bag and the scion's plastic wrap. The second pruning is done 60 days after grafting, cutting off excess branches of the rootstock and leaving only branches that do not compete with the surviving scion. The third pruning is done one year after grafting, retaining the branches of the surviving scion and removing all other branches.