Construction method of high-heartwood-rate Chinese toon tree breeding population special for solid wood furniture

Abstract

The invention discloses a method for constructing a high-heartwood-rate Chinese toon tree breeding population special for solid wood furniture. The method comprises the following steps: (1) selecting superior Chinese toon trees from a natural forest stand, wherein the natural forest stand is distributed in a region with the latitude of 27-32 degrees in north latitude, the longitude of 108-121 degrees in east longitude, the altitude of 150-800 m and the annual precipitation of 500-1900 mm; (2) constructing a clone of the superior toona sinensis: in November to December, collecting an annual branch at the middle upper part of a crown of the superior toona sinensis as a scion, sealing a cut of the scion with wax, and putting the scion into a sealing bag for cold storage at 4 DEG C; grafting the scion to the stock in mid-to-late February of the next year, and obtaining the superior clone of the toona sinensis after the grafting survives. According to the method, the breeding population can bloom within 3-5 years, the hybrid combination configuration requirement is met, high-heartwood-rate high-quality germplasm is rapidly obtained, and the breeding efficiency and quality are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of genetic breeding technology for Toona sinensis. Specifically, it relates to a method for constructing a breeding population of Toona sinensis with a high heartwood content, specifically for solid wood furniture. Background Technology

[0002] Toona sinensis is a general term for tree species in the genus Toona of the family Meliaceae, including Toona sinensis, Toona ciliata var. pubescen, Toona ciliate Roem., Toona sureni Blume Merrill, and Toona fargesii, among others. It is widely distributed across 22 provinces in China and has a cultivation history of over 2300 years. Toona sinensis grows rapidly and has a straight, round trunk, making it a valuable solid wood timber for furniture in my country, often referred to as "Chinese mahogany." Due to its high timber value, Toona sinensis plays a significant role in promoting national health and increasing farmers' income. Therefore, it is urgent to establish a breeding population and create high-quality germplasm with high heartwood content to lay the foundation for long-term breeding of Toona sinensis. Summary of the Invention

[0003] Therefore, the technical problem to be solved by this invention is to provide a method for constructing a high heartwood ratio ailanthus breeding population specifically for solid wood furniture. This method enables the breeding population to flower within 3-5 years, meeting the requirements for hybridization combinations, rapidly obtaining high-quality germplasm with a high heartwood ratio, and significantly improving breeding efficiency and quality.

[0004] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0005] A method for constructing a high heartwood ratio Toona sinensis breeding population specifically for solid wood furniture includes the following steps:

[0006] (1) Select superior Toona sinensis trees from natural forest stands: The natural forest stands are distributed in areas with latitudes of 27° to 32° north, longitudes of 108° to 121° east, altitudes of 150 to 800 m, and annual precipitation of 500 to 1900 mm.

[0007] (2) Constructing superior clonal lines of Toona sinensis: In November and December, one-year-old branches from the upper part of the crown of selected superior Toona sinensis trees are collected as scions. The cut ends of the scions are sealed with wax and stored in sealed bags at 4°C. In mid-to-late February of the following year, the scions are grafted onto the rootstock. After successful grafting, superior clonal lines of Toona sinensis are obtained. The superior clonal lines of Toona sinensis are cultivated for one year.

[0008] (3) Selection of afforestation site: The afforestation site is a slope, located on the middle and lower slope of the southern slope of a mountain at an altitude of 150-180m in the mid-subtropical or southern subtropical zone, with a slope of 30°-35°. The average annual temperature of the afforestation site is 15-18℃, the frost-free period is greater than or equal to 230 days, and the average annual precipitation is 500-1900mm.

[0009] (4) Breeding population construction: Dig horizontal strips in the afforestation area and dig planting holes in each horizontal strip. Transplant the superior clonal line of Toona sinensis after one year of cultivation into the planting holes and cut the trunk of the superior clonal line of Toona sinensis immediately after transplanting. The superior clonal line of Toona sinensis after transplanting is the breeding population of Toona sinensis.

[0010] The above-mentioned method for constructing a high heartwood ratio Toona sinensis breeding population specifically for solid wood furniture, in step (1), the selection criteria for superior Toona sinensis trees include: straight trunk, basic wood density greater than 0.5 g / cm3, heartwood ratio greater than 75%, and heartwood color reddish-brown without pests or diseases. These selection criteria ensure that the selected superior Toona sinensis trees possess high wood quality (such as wood density and heartwood ratio). This high-quality wood is crucial for solid wood furniture production, guaranteeing the wood's strength, durability, and aesthetics, meeting the requirements of solid wood furniture for wood properties.

[0011] In the above-mentioned method for constructing a high heartwood ratio Toona sinensis breeding population specifically for solid wood furniture, in step (2), when grafting scions onto the rootstock, the length of the scions used is 4-5 cm, and each scion has 1-2 plump buds. Selecting appropriate scion length and number of buds can improve the grafting success rate and ensure that the cultivated clones have strong growth vitality and wood quality. The superior Toona sinensis clones propagated by grafting can maintain excellent wood properties and are suitable for the production needs of solid wood furniture.

[0012] In the above-mentioned method for constructing a high heartwood rate Toona sinensis breeding population for solid wood furniture, in step (2), grafting is performed using the branch grafting method, with a grafting height of 10-15cm. The grafting height is the height of the grafting position from the ground. When the grafting height is 10-15cm, it can effectively prevent the cut and scion from being threatened by ground pathogens and pests, and ensure that the grafting part receives sufficient nutrition, thereby improving the success rate of grafting.

[0013] The above-mentioned method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture uses one-year-old seedlings of Toona sinensis as rootstock and individuals of any species in the Toona genus as scions.

[0014] In the above-mentioned method for constructing a high heartwood rate Toona sinensis breeding population for solid wood furniture, in step (2), after the grafting is successful, the superior Toona sinensis clones are watered, fertilized, and have their buds removed.

[0015] In the above-mentioned method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture, in step (3), the soil of the afforestation site is classified according to the Kachinsky system, with light clay accounting for 20% to 40% of the total soil mass and medium loam accounting for 40% to 60% of the total soil mass; the soil of the afforestation site is acidic. Selecting afforestation sites with suitable soil structure and pH is conducive to the healthy growth of Toona sinensis. Moreover, when selecting afforestation sites, selecting according to the limited soil structure and pH is conducive to maintaining the stability of the wood properties of Toona sinensis, further improving the quality of the wood and the stability of the timber, which meets the consistency requirements of solid wood furniture production.

[0016] The above-mentioned method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture involves, in step (4), digging horizontal strips from top to bottom along contour lines, with a spacing of 2 m between any two adjacent horizontal strips and a width of 4 m for each horizontal strip; planting holes within the same horizontal strip are considered as a row, with a distance of 6 m between the projections of two adjacent rows of planting holes on the horizontal plane; and within the same row of planting holes, the distance between two adjacent planting holes is 6 m. This horizontal strip layout method ensures sufficient growth space and light resources for Toona sinensis, avoids growth competition that may result from overly dense planting, and optimizes the cultivation environment through reasonable spacing, thereby improving the growth efficiency and wood quality of the breeding population. The ultimate goal is to improve the overall quality of the wood required for solid wood furniture production.

[0017] In the above-mentioned method for constructing a high heartwood rate Toona sinensis breeding population for solid wood furniture, in step (4), one-year-old seedlings with a height greater than 75cm, free from pests and diseases, and capable of overwintering outdoors at a minimum ambient temperature of 3℃ are selected and transplanted into planting holes; when cutting back the trunks of the transplanted Toona sinensis clones, the cutting height is 30-40cm. The cutting height of 30-40cm means that the height of the Toona sinensis clones after cutting back is 30-40cm. Cutting back is to improve the survival rate of transplanting, promote root growth, and facilitate management. However, it should be noted that the specific cutting height is the result of comprehensive consideration based on the growth characteristics of Toona sinensis and the climatic conditions of the afforestation site in February. When the cutting height is too high, the growth momentum of Toona sinensis weakens, the survival rate is low, and after cutting back at a high position, the tree may form a weak apical dominance, resulting in slow growth of the lower part of the trunk and forming defects such as "knots" or "bending". When the trunk is cut too low, the trunk is more susceptible to pests and diseases and is more likely to dry out.

[0018] In the above-mentioned method for constructing a high heartwood rate Toona sinensis breeding population for solid wood furniture, in step (2), before grafting, a healing promoter is sprayed onto the cut surfaces of the scion and rootstock. The healing promoter contains the following components at the following concentrations: 0.3 wt%–0.5 wt% IBA, 0.2 wt%–0.5 wt% NAA, and 0.1 wt%–0.3 wt% polyvinyl alcohol. IBA and NAA accelerate the rapid formation of callus tissue, while polyvinyl alcohol promotes the mutual healing of callus tissue between the scion and rootstock, which helps to improve the grafting survival rate. At the same time, the low concentration of PVA forms a protective film on the cut surface, effectively reducing moisture loss and lowering the risk of pathogen invasion, providing a stable and growth-friendly microenvironment for the grafting site.

[0019] The technical solution of the present invention achieves the following beneficial technical effects:

[0020] 1. The method provided by this invention can obtain a breeding population of Toona sinensis with high timber quality, especially high heartwood percentage. Through long-term experiments, the inventors determined the relationship between timber properties such as basic density, heartwood color, and heartwood percentage of the mother trees and ecological environment factors of the stand (mother trees)'s origin, establishing a strategy of "selecting superior Toona sinensis trees from stands originating from low latitudes, low longitudes, mid-to-high altitudes, and areas with low annual precipitation." By precisely selecting superior Toona sinensis individuals (e.g., straight trunks, timber density greater than 0.5 g / cm³, heartwood percentage greater than 75%, reddish-brown heartwood color, and free from pests and diseases) and employing scientific breeding methods (grafting), transplanting them to suitable afforestation sites with appropriate soil and climate, and using scientific management methods, the resulting Toona sinensis breeding population is ensured to have high heartwood percentage and timber quality. Experiments show that the offspring of the breeding population constructed using this method can consistently maintain high timber quality and heartwood percentage. This is especially important for the production of solid wood furniture, as the method provided by this invention can provide strong, durable and beautiful wood, meeting the furniture industry's high standards for wood quality.

[0021] 2. This invention ensures that the breeding population maintains the superior traits of *Toona sinensis* trees by constructing and scientifically managing superior clonal lines. This method effectively avoids the problems of unstable genetic diversity and uneven wood properties that may arise from traditional seed propagation, thus greatly improving the reliability and consistency of breeding. Furthermore, this invention selects suitable afforestation sites and optimizes the cultivation process by combining scientific cultivation management measures (such as horizontal strip land preparation, planting pit layout, dense planting, and trunk cutting techniques). These measures not only contribute to the rapid growth of *Toona sinensis* trees but also accelerate tree maturation through grafting and trunk cutting techniques, enabling the breeding population to flower within 3 to 5 years, significantly shortening the breeding cycle. Compared to traditional seed propagation methods, the flowering time is advanced by approximately 5 years. This advancement greatly improves breeding efficiency and enables the rapid acquisition of highly adaptable hybrid germplasm, further accelerating the breeding cycle and meeting the demand for rapid breeding of high-quality *Toona sinensis* trees.

[0022] 3. This invention employs high-standard screening to select superior Toona sinensis germplasm with high heartwood ratios, ensuring that the resulting Toona sinensis breeding population possesses high timber potential, and that the offspring produced by this breeding population are suitable for the production of high-quality solid wood furniture. Compared to conventional breeding methods, the breeding population construction technology provided by this invention not only improves the efficiency of Toona sinensis breeding but also enhances the stability and consistency of the timber. These characteristics significantly increase the market value of the timber, making the final product more competitive in the market. Detailed Implementation

[0023] Example 1

[0024] The method for constructing a high heartwood ratio ailanthus breeding population for solid wood furniture in this embodiment includes the following steps:

[0025] (1) Select superior Toona sinensis trees from natural forest stands in Kaihua County, Zhejiang Province. By collecting resources from natural Toona sinensis forest stands, analyzing the genetic variation of wood properties such as basic wood density, heartwood color and heartwood percentage in different forest stands, and obtaining the relationship between these traits and ecological environment factors of the forest stand's origin, the inventors determined a strategy to select superior Toona sinensis trees from forest stands with low latitude, low longitude, medium and high altitude and low annual precipitation.

[0026] In other embodiments, the natural forest stand can be a natural forest stand distributed in an area with latitudes of 27°–32°N, longitudes of 108°–121°E, altitudes of 150–800m, and annual precipitation of 500–1900mm. When selecting superior Toona sinensis trees from these natural forest stands, individuals with straight trunks, dark heartwood, a large proportion of heartwood, and strong adaptability should be selected. Specifically, the basic wood density of the selected superior Toona sinensis trees should be greater than 0.5g / cm³. 3The heartwood percentage should be greater than 75%, the heartwood color should be reddish-brown, and there should be no diseases or pests. Such Toona sinensis trees have suitable hardness, a high heartwood percentage, and beautiful heartwood color, making them valuable for solid wood furniture and easy to graft.

[0027] All species in the Toona genus are suitable for producing solid wood furniture, and the aforementioned superior Toona trees can be individuals from any species in the Toona genus.

[0028] (2) Constructing a clone of superior Toona sinensis trees: The dormancy period of Toona sinensis is from November to December. During the dormancy period, one-year-old branches from the upper part of the crown of selected superior Toona sinensis trees are collected as scions. The cut ends of the scions are sealed with wax to reduce moisture loss and maintain their vitality. The wax-sealed scions are then stored in sealed bags at 4℃. Grafting is carried out in mid-to-late February. One-year-old seedlings (seedlings) of Toona sinensis are selected as rootstocks for grafting. The scions are 4-5 cm long, and each scion has 1-2 plump buds. The grafting method is used, and the grafting height (i.e., the height of the grafting position from the ground) is 10-15 cm. The grafting cut is wrapped with grafting film to ensure that the scion and rootstock are closely connected to form callus tissue. After grafting, timely management measures such as watering, fertilizing, and bud removal should be taken to promote the growth of callus tissue and improve the grafting survival rate. After successful grafting, superior clonal lines of Toona sinensis are obtained. These superior clonal lines are then cultivated for one year before being transplanted.

[0029] (3) Selection of afforestation sites: Based on the geographical location and climate characteristics of the core natural distribution area of ​​Toona sinensis, the suitable areas for establishing Toona sinensis breeding populations are the mid-subtropical and south-subtropical regions. Kaihua County in western Zhejiang Province, located in the mid-subtropical region, was selected to establish the Toona sinensis breeding population. The county has an average annual temperature of 16.6℃, a frost-free period of 254 days, and an average annual precipitation of 1830.8 mm. The afforestation site is located at an altitude of 150-180m, on the middle and lower slope of the southern slope of the mountain, with a slope of 30-35°. The soil is mainly red soil and yellow soil, with a texture of medium loam to light clay (according to the Kachinsky system, light clay accounts for 20%-40% of the total soil mass, and medium loam accounts for 40%-60% of the total soil mass), and the soil is acidic.

[0030] (4) Breeding population establishment: Clear the afforestation land and then prepare the horizontal strips. Dig horizontal strips in the afforestation land from top to bottom along the contour lines. The distance between any two adjacent horizontal strips is 2 m, and the width of each horizontal strip is 4 m. Dig planting holes in each horizontal strip, with the planting holes in the same horizontal strip as a row. The distance between the vertical projections of two adjacent rows of planting holes on the horizontal plane is 6 m. In the same row of planting holes, the distance between two adjacent planting holes is 6 m. Transplant fast-growing (1-year-old seedlings are taller than 75 cm), cold-resistant (can overwinter outdoors at a minimum ambient temperature of 3℃), and disease-free superior clonal lines of Toona sinensis into the planting holes. Immediately after transplanting, cut the trunks of the superior clonal lines of Toona sinensis to a height of 30-40 cm. Table 1 is a configuration diagram of the superior clonal lines of Toona sinensis in Example 1.

[0031] Table 1

[0032]

[0033] The superior clones of Toona sinensis trees that survive after afforestation are called Toona sinensis breeding populations.

[0034] After the establishment of the Toona sinensis breeding population, it should be managed. Management measures include: applying nitrogen-based fertilizers; pruning excessively long upper branches after leaf fall in autumn to encourage branch growth towards the periphery of the canopy; and effective weeding and pest and disease control. The parent materials of this breeding population can flower in 3-5 years, which is 5 years earlier than existing grafting techniques. Furthermore, the parent materials of this breeding population can meet the requirements for hybridization combinations, obtaining new hybrid germplasm and selecting high-quality Toona sinensis germplasm with a high heartwood rate specifically for solid wood furniture.

[0035] Comparative Example 1

[0036] This comparative example provides a method for constructing a Toona sinensis breeding population, including the following steps:

[0037] Step 1: Select high-performing mother trees from natural Toona sinensis forests for seed collection. The selected mother trees are from the same natural stand and are of the same variety as the Toona sinensis scion donors in Example 1. The selection criteria for mother trees are also the same as in Example 1. After seed collection, the seeds are soaked to improve the germination rate, and then seedlings are raised in a greenhouse. The seedling period is approximately 2-3 months, during which the seedlings are cultivated in the greenhouse to ensure they reach the appropriate age and growth status.

[0038] Step 2: Within one year of seedling establishment, select individuals with rapid growth, excellent wood properties, and strong resistance to diseases and pests as superior parent plants by observing growth, wood characteristics, and disease and pest resistance. Parent plant selection criteria include: rapid growth (one-year-old seedlings taller than 75cm) and freedom from diseases and pests. Superior parent plants should be selected in diverse ways across different forest stands and environments to ensure high genetic diversity within the population.

[0039] Step 3: Select a suitable afforestation site based on the growth characteristics of the ailanthus tree. The site selection and land preparation methods in this step are the same as in Example 1.

[0040] Step 4: Plant the selected superior parent trees in planting holes in the afforestation area. During the initial growth stage, implement necessary water and fertilizer management and pest and disease control measures. Fertilize regularly each year, paying attention to the balance of nitrogen, phosphorus, and potassium fertilizers to promote tree growth.

[0041] After the *Toona sinensis* breeding populations in Example 1 and Comparative Example 1 entered the flowering period, they were allowed to undergo natural pollination within their respective populations. The F1 generation seeds obtained from both populations were then planted near the parent populations, resulting in two F1 generation populations. The F1 generation populations were evaluated 15 years after planting, and the results are shown in Table 2.

[0042] Table 2

[0043]

[0044] As shown in Table 2, regarding flowering time: Example 1 used asexual reproduction and the strategy of using superior Toona sinensis clones, which greatly advanced the flowering time of the breeding population, shortening it from 8-10 years in conventional breeding to 3 years. This is crucial for quickly obtaining superior varieties and improving breeding efficiency.

[0045] Regarding the survival rate, the survival rate of the breeding population in Example 1 was 95%, which was higher than the 92% of the breeding population in Comparative Example 1. This may be due to the individual superior clones in the breeding population of Example 1, which have high genetic stability and whose excellent traits can be stably inherited to the F1 generation.

[0046] The breeding population in Comparative Example 1, obtained directly from seedlings, exhibited a high genetic diversity index. In contrast, the breeding population in Example 1 showed reduced genetic diversity, reflecting that asexual reproduction may result in lower genetic diversity but better maintains the stability of desirable traits. Measurements of the average heartwood percentage and basic wood density of the F1 generation showed that in Example 1, due to the selection of superior *Toona sinensis* trees with high heartwood percentage and high wood density as parents, the heartwood percentage (80%) and wood density (0.52 g / cm³) of the F1 generation were significantly higher than those of the F1 generation in Comparative Example 1 (65%) and 0.45–0.5 g / cm³, respectively. This indicates that Example 1 exhibits superior wood quality and is suitable for solid wood furniture production.

[0047] The results above demonstrate that, in Example 1, the use of asexual reproduction technology, the construction of superior ailanthus clones, and scientific breeding management not only significantly shortened the flowering time of the parent ailanthus and improved the transplant survival rate, but also more effectively ensured that the offspring produced by the parent ailanthus focused on and maintained superior traits (such as high heartwood ratio and high wood density), resulting in a breeding population with higher economic value and breeding efficiency. In contrast, while conventional breeding methods offer higher genetic diversity, they have certain shortcomings in terms of breeding efficiency and wood quality.

[0048] Example 2

[0049] In this embodiment, the method for constructing asexual grafting of superior Toona sinensis trees was improved based on Embodiment 1.

[0050] In this embodiment, before grafting, a healing promoter is evenly sprayed onto the incisions of both the rootstock and the scion using a sprayer. The healing promoter contains 0.4 wt% IBA (indole-3-butyric acid), 0.3 wt% NAA (naphthaleneacetic acid), and 0.2 wt% polyvinyl alcohol. IBA and NAA accelerate callus formation at the grafting site, while PVA promotes the healing of the callus tissue between the rootstock and scion. Simultaneously, PVA forms a protective film on the incision surface, reducing moisture loss and lowering the risk of pathogen invasion.

[0051] In other embodiments, the healing promoter may contain components in the following concentration ranges: 0.3wt% to 0.5wt% of IBA, 0.2wt% to 0.5wt% of NAA, and 0.1wt% to 0.3wt% of polyvinyl alcohol.

[0052] Comparative Example 2

[0053] Based on Example 2, this comparative example changed the formulation of the healing promoter. Polyvinyl alcohol was no longer added to the healing promoter, which only contained 0.4 wt% IBA and 0.3 wt% NAA.

[0054] For the *Toona sinensis* trees grafted using the methods in Example 2 and Comparative Example 2, respectively, the grafting survival rate was calculated 60 days after grafting. The results showed that in the case of interspecies grafting (where the scion and rootstock belong to different species of *Toona sinensis*), the grafting survival rate in Example 2 was approximately 72.3%, significantly higher than the 53.1% in Comparative Example 2. The incidence of scion drop and necrosis in interspecies grafts treated with the healing promoter in Example 2 was significantly lower than that treated with the healing promoter in Comparative Example 2. This indicates that the PVA-containing healing promoter provided in Example 2 effectively promotes the healing of callus tissue from different species of *Toona sinensis* together.

[0055] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of the claims of this patent application.

Claims

1. A method for constructing a high heartwood ratio ailanthus breeding population specifically for solid wood furniture, characterized in that, Includes the following steps: (1) Select superior Toona sinensis trees from natural forest stands: The natural forest stands are distributed in areas with latitudes of 27° to 32° north, longitudes of 108° to 121° east, altitudes of 150 to 800 m, and annual precipitation of 500 to 1900 mm. (2) Constructing superior clonal lines of Toona sinensis: In November and December, one-year-old branches from the upper part of the crown of selected superior Toona sinensis trees are collected as scions. The cut ends of the scions are sealed with wax and stored in sealed bags at 4°C. In mid-to-late February of the following year, the scions are grafted onto the rootstock. After successful grafting, superior clonal lines of Toona sinensis are obtained. The superior clonal lines of Toona sinensis are cultivated for one year. (3) Selection of afforestation site: The afforestation site is a slope, located on the middle and lower slope of the southern slope of a mountain at an altitude of 150-180m in the mid-subtropical or southern subtropical zone, with a slope of 30°-35°. The average annual temperature of the afforestation site is 15-18℃, the frost-free period is greater than or equal to 230 days, and the average annual precipitation is 500-1900mm. (4) Breeding population construction: Dig horizontal strips in the afforestation area and dig planting holes in each horizontal strip. Transplant the superior clonal line of Toona sinensis after one year of cultivation into the planting holes and cut the trunk of the superior clonal line of Toona sinensis immediately after transplanting. The superior clonal line of Toona sinensis after transplanting is the breeding population of Toona sinensis.

2. The method for constructing a high heartwood ratio *Toona sinensis* breeding population specifically for solid wood furniture according to claim 1, characterized in that, In step (1), the selection criteria for superior Toona sinensis trees include: straight trunk and a basic wood density greater than 0.5 g / cm³. 3 The heartwood content is greater than 75%, the heartwood is reddish-brown in color and free from diseases and pests.

3. The method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture as described in claim 1, characterized in that, In step (2), when grafting scions onto the rootstock, the scions used are 4 to 5 cm long and each scion has 1 to 2 plump buds.

4. The method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture as described in claim 3, characterized in that, In step (2), grafting is performed using the branch grafting method, with a grafting height of 10-15cm.

5. The method for constructing a high heartwood ratio *Toona sinensis* breeding population specifically for solid wood furniture according to claim 4, characterized in that, The rootstock for grafting is a one-year-old seedling of Toona sinensis, and the scion is an individual from any species of the Toona genus.

6. The method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture as described in claim 3, characterized in that, In step (2), after the grafting is successful, the superior clonal line of Toona sinensis is watered, fertilized and buds are removed.

7. The method for constructing a high heartwood ratio *Toona sinensis* breeding population for solid wood furniture as described in claim 1, characterized in that, In step (3), the soil of the afforestation site is classified according to the Kachinsky system, with light clay accounting for 20% to 40% of the total soil mass and medium loam accounting for 40% to 60% of the total soil mass; the soil of the afforestation site is acidic.

8. The method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture as described in claim 1, characterized in that, In step (4), horizontal strips are excavated from top to bottom along the contour lines. The distance between any two adjacent horizontal strips is 2m, and the width of each horizontal strip is 4m. The planting holes in the same horizontal strip are considered as a row, and the distance between the projections of two adjacent rows of planting holes on the horizontal plane is 6m. In the same row of planting holes, the distance between two adjacent planting holes is 6m.

9. The method for constructing a high heartwood ratio *Toona sinensis* breeding population for solid wood furniture as described in claim 8, characterized in that, In step (4), select a clonal line of Toona sinensis with a height greater than 75cm, free from pests and diseases, and capable of overwintering outdoors at a minimum ambient temperature of 3℃, and transplant them into the planting hole; when cutting the trunk of the transplanted clonal line of Toona sinensis, the cutting height is 30-40cm.

10. The method for constructing a high heartwood ratio Toona sinensis breeding population for solid wood furniture as described in claim 1, characterized in that, In step (2), before grafting, a healing promoter is sprayed onto the cut of the scion and the cut of the rootstock; the healing promoter contains the following components at the following concentrations: 0.3 wt% to 0.5 wt% of IBA, 0.2 wt% to 0.5 wt% of NAA, and 0.1 wt% to 0.3 wt% of polyvinyl alcohol.

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