A phoebe seedling processing method based on cutting and quantitative pruning

Abstract

The present application belongs to the technical field of forest cultivation, and particularly relates to a processing method for Phoebe bournei seedlings based on stem cutting and quantitative pruning. The present application is characterized in that the seedlings are pinched when the height-diameter ratio is less than or equal to 80, and the stem is cut when the height-diameter ratio is greater than 80 and less than or equal to 100. After the stem is cut, the dry height is equal to the ground diameter multiplied by 80, and a light dry area with a height of 5-8 cm is formed below the cutting surface, and the light dry area contains growth nodes or more than 3 leaves without side branches. The quantitative pruning amount is 1 / 2-2 / 3, and after the dominant branch at the top appears, the other sprouting branches in the light dry area are removed at one time. The method of the present application can quickly cultivate straight trunks, and the formation rate of the dominant branch at the top reaches 96%. In the third year, the ground diameter growth amount reaches 1.47 cm, and the height growth reaches 76 cm, which are increased by 31.3% and 81.0% respectively compared with the control. The lodging rate is reduced to 5.0%, and the irrigation frequency is reduced by 43%. The present application realizes the rapid formation of the dominant branch at the top and the sustained growth activity, and cooperatively achieves the cultivation goal of drought resistance and lodging resistance, and is suitable for efficient seedling raising and afforestation of Phoebe bournei.

Description

Technical Field

[0001] This invention belongs to the field of forest tree cultivation technology, specifically relating to a method for treating Phoebe zhennan seedlings based on trunk cutting and quantitative pruning. Background Technology

[0002] Minnan [ Phoebe bournei [Hemsl.] Yang, a precious timber species unique to my country and a national second-class protected plant, not only boasts excellent wood quality and high economic value but also plays a vital role in maintaining regional ecological balance and biodiversity. In the process of promoting the afforestation of *Phoebe zhennan*, managers typically use robust, vigorous seedlings with well-developed root systems and ample nutrient reserves, carefully cultivated in the nursery stage, directly for afforestation. However, in this approach, the full crown and newly sprouted spring shoots of these robust seedlings quickly become powerful centers of nutrient and water consumption. Affected by transplanting damage and site stress, the root system's recovery and growth process is relatively slow, leading to a severe imbalance between above-ground and below-ground growth. This results in subsequent weak growth and seriously hinders the efficient cultivation of *Phoebe zhennan* timber forests.

[0003] To address the aforementioned issues, existing technologies typically employ trunk cutting or pruning to reduce the transpiration area of ​​the above-ground parts, thereby maintaining the water balance within the seedlings and improving the survival rate in the early stages of afforestation. However, for high-quality, robust seedlings, survival rate is not the primary concern. Existing technologies have significant shortcomings in addressing the core quality indicator of trunk straightness. While simple trunk cutting can temporarily suppress apical growth, it easily induces the rapid sprouting of lower lateral branches, forming new and uncontrollable apical dominance. Ultimately, this leads to bent or forked trunks, severely deteriorating the trunk shape and failing to meet the cultivation standards for high-end, precious timber. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for treating Phoebe zhennan seedlings based on trunk cutting and quantitative pruning. This method can effectively coordinate the above-ground and underground growth relationship of robust Phoebe zhennan seedlings and accurately cultivate straight trunks, simultaneously achieving the cultivation goals of well-developed root systems and straight trunks.

[0005] This invention provides a method for treating Phoebe zhennan seedlings based on trunk cutting and quantitative pruning, comprising the following steps: Measure the height and diameter at ground level of the *Phoebe zhennan* seedlings, and calculate the height-to-diameter ratio; When the height-to-diameter ratio of the *Machilus chinensis* seedlings is >80 and ≤100, the trunk is cut off to obtain truncated seedlings; when the height-to-diameter ratio of the *Machilus chinensis* seedlings is ≤80, the terminal bud is pinched off to obtain pinched seedlings. The trunk height of the cut-off seedling is equal to the ground diameter × 80, and the bare trunk area is 5-8cm below the cut. The bare trunk area has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth node and contains at least 3 growth leaves. Quantitative pruning is carried out on the cut-off or pinched-off seedlings, and the amount of pruning is controlled to 1 / 2 to 2 / 3 of the total number of branches and leaves of the plant after the cut-off or pinching-off; after the apical dominant branch appears, all other sprouting branches on the bare trunk area are removed at once.

[0006] Preferably, the diameter at ground level of the *Phoebe zhennan* seedling is 1.5-2.5 cm.

[0007] Preferably, the condition (2) is: when there are no growth nodes, it contains 3-5 growth leaves.

[0008] Preferably, the condition (1) is: containing at least one growth node and at least one growth leaf.

[0009] Preferably, during the quantitative pruning, the focus is on removing inner branches, overlapping branches, diseased and insect-infested branches, and weak branches in the lower part of the canopy, while the remaining lateral branches are shortened.

[0010] This invention provides a cultivation model for Phoebe bournei, including a tree structure, wherein the tree structure includes a truncated main trunk, and a bare trunk area 5-8cm below the truncated main trunk. The height of the truncated main trunk is equal to the ground diameter × 80. The bare section has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth nodes and contains 3-5 growth leaves. After the apical dominance of the *Machilus chinensis* cultivation model is observed, the bare trunk area contains only one apical dominant branch.

[0011] Preferably, the height-to-diameter ratio of the truncated main trunk before truncation is greater than 80 and less than or equal to 100.

[0012] This invention provides a truncated seedling of *Machilus chinensis*, which is a truncated or pinched seedling of *Machilus chinensis* from a nursery. The truncated seedling has a trunk height of = ground diameter × 80, and a bare trunk area of ​​5-8 cm below the truncated section. The bare trunk area has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth nodes and contains at least 3 growth leaves. The amount of branches and leaves pruned for the cut-off or pinched-off seedlings is 1 / 2 to 2 / 3 of the amount of branches and leaves of the nursery seedlings after the cut-off or pinching-off.

[0013] Preferably, the height-to-diameter ratio of the *Phoebe zhennan* nursery seedlings is >80 and ≤100.

[0014] This invention provides the above-described method for treating *Phoebe zhennan* seedlings, the above-described cultivation model for *Phoebe zhennan*, or the application of the above-described cut-off *Phoebe zhennan* seedlings in *Phoebe zhennan* afforestation.

[0015] Beneficial effects: This invention provides a method for treating *Phoebe zhennan* seedlings based on trunk cutting and quantitative pruning. Trunk cutting or pinching is performed according to the height-to-diameter ratio, and quantitative pruning allows for precise control of the axillary bud germination time window, creating a physiological buffer period for the root system. The defined bare trunk area receives sufficient nutrients, promoting rapid apical dominance and ensuring a straight, branchless main trunk. Root development is significantly promoted, with substantial increases in trunk diameter and height growth in the first year and the following two years, a significant reduction in lodging rate, and greatly enhanced drought resistance. The *Phoebe zhennan* seedling treatment method provided by this invention is simple to operate, low in cost, and suitable for the targeted cultivation of robust *Phoebe zhennan* seedlings and valuable timber forests. Detailed Implementation

[0016] This invention provides a method for treating Phoebe zhennan seedlings based on trunk cutting and quantitative pruning, comprising the following steps: Measure the height and diameter at ground level of the *Phoebe zhennan* seedlings, and calculate the height-to-diameter ratio; When the height-to-diameter ratio of the *Machilus chinensis* seedlings is >80 and ≤100, the trunk is cut off to obtain truncated seedlings; when the height-to-diameter ratio of the *Machilus chinensis* seedlings is ≤80, the terminal bud is pinched off to obtain pinched seedlings. The trunk height of the cut-off seedling is equal to the ground diameter × 80, and the bare trunk area is 5-8cm below the cut. The bare trunk area has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth node and contains at least 3 growth leaves. Quantitative pruning is carried out on the cut-off or pinched-off seedlings. The amount of pruning is controlled to 1 / 2 to 2 / 3 of the total number of branches and leaves of the plant after the cut-off or pinching. After the dominant apical branch appears, all other sprouting branches on the bare trunk area are removed at once.

[0017] This invention measures the height and diameter at ground level of *Machilus chinensis* seedlings, calculates the height-to-diameter ratio, and processes the seedlings according to the ratio. When the height-to-diameter ratio of the seedlings is >80 and ≤100, the trunk is cut off to obtain a truncated seedling; when the height-to-diameter ratio of the seedlings is ≤80, the top is pinched off to obtain a pinched seedling. The trunk height of the truncated seedlings is equal to the diameter at ground level × 80, and the 5-8cm below the cut is a bare trunk area. The bare trunk area has no lateral branches and meets the following conditions (1) or (2): (1) it contains at least one growth node; (2) it has no growth nodes and contains at least three growth leaves.

[0018] As one implementation method, the area 6-7 cm below the cut surface described in this invention is a light-drying zone.

[0019] In one embodiment, the diameter at ground level of the *Phoebe zhennan* seedlings of the present invention is 1.5-2.5 cm; in another embodiment, the diameter at ground level of the *Phoebe zhennan* seedlings of the present invention is 3.0 cm.

[0020] In one embodiment, condition (2) of the present invention is: when there is no growth node, it contains 3-5 growth leaves. In another embodiment, condition (1) of the present invention is: it contains at least one growth node and at least one growth leaf.

[0021] As one implementation method, the quantitative pruning method described in this invention focuses on removing inner branches, overlapping branches, diseased and insect-infested branches, and weak branches in the lower part of the canopy, while shortening the remaining lateral branches.

[0022] In one embodiment, the *Phoebe zhennan* seedlings described in this invention are robust *Phoebe zhennan* seedlings, cultivated in containers with a diameter of 20cm and a bag height of 20cm.

[0023] This invention completely eliminates apical dominance by pruning or topping the stem. The remaining nodes and functional leaves in the bare trunk provide sufficient nutrients for the germination of dormant buds, ensuring their successful emergence within 10-15 days. At this time, the root system gains physiological buffer due to reduced consumption from pruning; newly emerging axillary buds compete, and based on the strong apical dominance of *Machilus macrantha*, the highest-positioned and most vigorous axillary bud rapidly synthesizes auxin and transports it downwards, inhibiting other lateral buds and naturally forming a single main stem. The bare trunk is located below the pruning cut, allowing the new main stem to sprout vertically without needing to be straightened; pruning promotes the preferential transport of photosynthetic products to the roots and main stem, achieving synergistic growth in both thickness and height. This invention removes apical inhibition, promotes nutrient redistribution, and accelerates the thickening of the main stem; pruning reduces the physiological burden on the roots, providing a buffer for root repair. These two factors work together to lay the foundation for robust growth of the main stem. Furthermore, the pruning treatment of this invention optimizes the diameter-to-height ratio, enhancing the root system's anchoring ability. In the year and the following two years, the thickness and height of the plants increased significantly, the lodging rate decreased drastically, and the drought resistance was greatly enhanced. Limiting the length of the dry zone can achieve the optimal balance between the timing, number and quality of axillary bud germination. A length less than 5cm or more than 8cm will result in a significant decrease in the effect.

[0024] This invention provides a cultivation model for Phoebe bournei, including a tree-shaped structure, wherein the tree-shaped structure includes a truncated main trunk, characterized in that the area 5-8 cm below the truncated section of the main trunk is a bare trunk area; The height of the truncated main trunk is equal to the ground diameter × 80. The bare section has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth nodes and contains 3-5 growth leaves. After the apical dominance of the *Machilus chinensis* cultivation model is observed, the bare trunk area contains only one apical dominant branch.

[0025] In one embodiment, the height-to-diameter ratio of the truncated main trunk before truncation is >80 and ≤100.

[0026] This invention provides a truncated seedling of *Machilus chinensis*, which is a truncated or pinched seedling of *Machilus chinensis* from a nursery. The truncated seedling has a trunk height of = ground diameter × 80, and a bare trunk area of ​​5-8 cm below the truncated section. The bare trunk area has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth nodes and contains at least 3 growth leaves. The amount of branches and leaves pruned for the cut-off or pinched-off seedlings is 1 / 2 to 2 / 3 of the amount of branches and leaves of the nursery seedlings after the cut-off or pinching-off.

[0027] In one embodiment, the height-to-diameter ratio of the *Phoebe zhennan* seedlings in the nursery of the present invention is >80 and ≤100.

[0028] This invention preserves at least one node or 3-5 leaves in the trunk area, utilizing its abundant nutrients and dense latent buds to ensure early axillary bud sprouting and robust growth. By cutting back the trunk to eliminate apical dominance and combining this with quantitative pruning to provide a physiological buffer for root recovery, stable and straight apical dominance can be rapidly rebuilt in just 40-45 days, simultaneously achieving the cultivation goals of a well-developed root system and a straight trunk.

[0029] This invention provides the above-described method for treating *Phoebe zhennan* seedlings, the above-described cultivation model for *Phoebe zhennan*, or the application of the above-described cut-off *Phoebe zhennan* seedlings in *Phoebe zhennan* afforestation.

[0030] To further illustrate the present invention, the following detailed description of a method for treating Phoebe zhennan seedlings based on trunk cutting and quantitative pruning provided by the present invention is provided in conjunction with embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1 Experimental basis and general methods 1. Test site and materials All trials were conducted uniformly at the Nanmu (Phoebe zhennan) base of Jiangxi Longhua Health Agriculture Development Co., Ltd. in March 2023. The test seedlings were robust, large-sized container seedlings of 4-year-old Nanmu trees, with a ground diameter of 2.0±0.2cm, a height of 200±10cm, a height-to-diameter ratio of 100, and container dimensions of 20×20cm. The seedlings had well-developed root systems and had formed complete root clusters. The climate throughout 2023 was normal, with no extreme drought, flooding, or frost. The experimental afforestation sites were all hilly areas with moderate soil fertility. Conventional afforestation techniques were employed, including comprehensive clearing of weeds, pit preparation, digging holes according to plant spacing and applying base fertilizer, watering after planting, and two tending treatments in the same year (weeding, loosening the soil, and topdressing). These standard procedures ensured that all treatment groups maintained consistent management conditions except for the technical measures of this invention.

[0032] 2. General Operating Procedures The following embodiments are all based on the same basic operations (unless otherwise specified): (1) Cutting off the trunk: According to the method of the present invention, when 80 < H / D ≤ 100, the trunk height to be cut off is equal to the ground diameter × 80, that is, the height to be retained is about 160cm.

[0033] (2) Dry section: Retain a 6.5cm section with one complete growth node and no other lateral branches directly below the cut (remove all lateral branches if present).

[0034] (3) Quantitative pruning: The amount of pruning should be controlled at 1 / 2 to 2 / 3 of the volume of the plant's branches and leaves after the trunk is cut off (usually 1 / 2). Specific operation: Remove inner branches, overlapping branches, diseased and insect-infested branches and weak branches in the lower part of the canopy, and shorten the remaining lateral branches.

[0035] (4) One-time pruning: After the dominant apical branch appears, all other sprouting branches on the bare trunk area are removed in one go.

[0036] (5) Control: Conventional planting (no trunk cutting, no pruning).

[0037] 3. General Observation Indicators and Methods (1) Sprouting quality: A 1-5 point system is used, with 5 points being the best (plump buds, bright green color, and strong growth) and 1 point being the worst (small buds, dull color, and weak growth). After pruning, the newly emerging apical dominant branches are evaluated.

[0038] Table 1 Scoring Criteria for Germination Vigor

[0039] (2) Establishment time of apical dominance: The number of days from the time the trunk is cut off until a dominant new shoot that significantly inhibits other buds appears in the bare area.

[0040] (3) Apical dominance formation rate: The proportion of plants that can eventually form a single straight main stem.

[0041] (4) Diameter growth: The diameter at 5cm above the ground is measured with a digital vernier caliper in November of the same year. Growth = Diameter of the year - Diameter at the time of afforestation.

[0042] (5) High growth: Measure the length of the new shoots on the main trunk in November of the following year.

[0043] (6) Lodging rate: After the rainy season ends in May of the following year, the proportion of plants with a tilt angle ≥30° is counted.

[0044] (7) Root activity: The TTC method was used for determination from December of the current year to February of the following year. Ten plants were randomly selected from each group, and 0.5 g of fresh root samples were taken. 0.4% TTC solution and phosphate buffer were added, and the samples were incubated in the dark at 37℃ for 3 h. Ethyl acetate was added for extraction, and the absorbance was measured at 485 nm. The results are expressed in mg·g -1 ·h -1 express.

[0045] Example 2 The Influence of Different Light-Trunk Lengths on Axillary Bud Germination and Main Stem Health Formation 1. Experimental Design Six treatments were set up, with the lengths of the light-dried zone being 4, 5, 6, 7, 8, and 9 cm (all including the growing nodes), and 50 plants in each group. Except for the length of the light-dried zone, the other operations were the same as the general method in Example 1.

[0046] 2. Observation Indicators Number of buds and quality of buds.

[0047] 3. Results Table 2. Effects of different light-dry zone lengths on axillary bud germination

[0048] Note: Different letters in the same column indicate significant differences. p <0.05, the same applies below.

[0049] Table 2 shows that the sprouting quality of 4cm and 9cm treatments was poor (≤3.5 points), which is not conducive to the healthy formation of the main stem. Sprouting at 5-8cm was of moderate quantity and high quality. A bare stem length of 5-8cm is the optimal range, providing a foundation for high-quality sprouting.

[0050] Example 3 Effects of different pruning intensities on the time of axillary bud germination and apical dominance establishment 1. Experimental Design Five pruning intensities were set: 0% (no pruning), 1 / 3, 1 / 2, 2 / 3, and 1% (full pruning). Each group consisted of 40 plants. All treatments used the same trunk cutting operation (H / D=100, trunk height retained = ground diameter × 80) and bare trunk area (length 6.5cm, including growth nodes), only the amount of pruning varied.

[0051] 2. Observation Indicators The quality of germination and the time it takes to establish apical dominance.

[0052] 3. Results Table 3. Effects of different pruning intensities on the time of axillary bud germination and apical dominance establishment.

[0053] As shown in Table 3, the time to establish apical dominance for the full pruning treatment was 50.0 days, later than that for the 1 / 2-2 / 3 treatment. The pruning intensity of 1 / 2-2 / 3 yielded the best results while achieving high-quality bud break (4.7-4.8 points) and a relatively fast time to establish apical dominance (44.8-45.5 days).

[0054] Example 4 The impact of different types of light-induced aridity zones and conventional trunk cutting techniques on the formation of healthy trunks 1. Experimental Design There were 4 treatments, with 50 plants in each group: Including the growth node: The length of the bare trunk is 6.5cm, containing one complete growth node (without leaves or with a few leaves), and without lateral branches.

[0055] Contains 3-5 leaves: The length of the bare trunk is 6.5cm, with no growth nodes, but retains 3-5 functional leaves and no lateral branches.

[0056] No nodes or leaves: The length of the bare trunk is 6.5cm, the branch segment is completely smooth, and there are no growth nodes, no leaves, and no lateral branches.

[0057] Standard trunk pruning (with lateral branches): After pruning, one or more lateral branches are left in a 6.5cm section below the cut (i.e., there are lateral branches in the bare trunk area).

[0058] All treatments have the same stem cutting height (retained stem height = ground diameter × 80 = 160cm).

[0059] 2. Observation Indicators Number of buds, quality of buds, time to establish apical dominance, and rate of apical dominance formation.

[0060] 3. Results.

[0061] Table 4. The impact of different types of light-induced dryness zones and conventional trunk pruning on the formation of trunk health.

[0062] As shown in Table 4, conventional trunk pruning (leaving lateral branches) results in fewer and lower-quality axillary buds due to the presence of lateral branches in the bare trunk area. This leads to severe bending of the main trunk and a qualified main trunk formation rate of only 35%. In contrast, the bare trunk area with growth nodes exhibits the highest apical dominance formation rate (96%) and straight main trunks. Conventional trunk pruning (leaving lateral branches) results in severely bent main trunks and poor quality. Therefore, selecting a bare trunk area with growth nodes is the optimal method for cultivating straight main trunks.

[0063] Example 5 Effects of different height-to-diameter ratios on the growth, lodging resistance, and root vigor of *Phoebe zhennan* 1. Experimental Design Four treatments were set up, with 50 plants in each group. After pruning, different height-to-diameter ratios (H / D) were retained: 70, 80, 90, and 100 (unpruned). All treatments used the general method of removing the bare trunk (including the growing node) and pruning by 1 / 2, with the only difference being the pruning height.

[0064] 2. Observation Indicators The following year's lodging rate, current year's diameter at root, and root vigor.

[0065] 3. Results.

[0066] Table 5. Effects of different height-to-diameter ratios on the growth, lodging resistance, and root vigor of *Machilus macrantha* (increment based on H / D=100).

[0067] As shown in Table 5, H / D=70 and H / D=80 are comparable in terms of growth and lodging resistance, but H / D=70 wastes branch length and increases afforestation costs. Taking all factors into account, H / D=80 ensures an extremely low lodging rate (5.0%) and high growth while saving trunk material, making it the optimal choice that balances lodging resistance, growth, and economy.

[0068] Example 6 Effects of different pruning intensities on the growth, drought resistance, and root vigor of Phoebe bournei 1. Experimental Design Five pruning intensities were set: 0% (no pruning), 1 / 3, 1 / 2, 2 / 3, and 1% (full pruning). Each group consisted of 40 plants. All treatments used the same trunk cutting operation (H / D=100, trunk height retained = ground diameter × 80) and bare trunk area (length 6.5cm, including growth nodes), only the amount of pruning varied.

[0069] 2. Observation Indicators Annual diameter growth (cm), number of irrigations (drought resistance index), root activity (mg·g) -1 ·h -1 ).

[0070] 3. Results Table 6. Effects of different pruning intensities on the growth, drought resistance, and root vigor of *Machilus chinensis*.

[0071] As shown in Table 6, pruning by 1 / 2 to 2 / 3 increases the diameter at root of the plant by 37% to 42% in the current year, reduces irrigation frequency by 43% to 57%, and increases root vitality by 72% to 81%, resulting in the best overall effect. This intensity significantly enhances the drought resistance and growth potential of the seedlings.

[0072] Example 7 Synergistic effect verification (this invention vs. trunk cutting only vs. pruning only vs. control) 1. Experimental Design Four treatments were performed: ① This invention (trunk cutting + bare trunk area + 1 / 2 pruning); ② Trunk cutting only (same as this invention but without pruning); ③ Pruning only (no trunk cutting, 1 / 2 pruning); ④ Conventional planting (control). Each group consisted of 50 plants, with seedling specifications and management the same as in Example 1.

[0073] 2. Observation Indicators Second year diameter and height growth; third year diameter and height growth; second year lodging rate (lodging resistance); number of irrigations (drought resistance).

[0074] 3. Results.

[0075] Table 7. Cultivation status of *Machilus pungens* under different treatment groups in the drought year (2025)

[0076] As shown in Table 7, the treatment of this invention is significantly superior to other treatments in terms of growth vigor (76 cm height growth in the third year), lodging resistance (lodging rate of 5.0%), and drought resistance (4 irrigations). The actual effect exceeds the simple sum of trunk cutting and branch pruning, proving that trunk cutting and branch pruning have a significant synergistic effect, and can simultaneously achieve the cultivation goal of rapidly forming a straight trunk, strong growth vigor, and high stress resistance.

[0077] As can be seen from the above, this invention is simple to operate, low in cost, and has stable effects. It is suitable for afforestation of Phoebe zhennan under various site conditions, and has important promotion and application value, especially in the high-efficiency seedling cultivation and timber forest construction of Phoebe zhennan. It can be used for high-efficiency cultivation under difficult site conditions such as drought and barrenness.

[0078] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for treating *Phoebe zhennan* seedlings based on trunk cutting and quantitative pruning, characterized in that, Includes the following steps: Measure the height and diameter at ground level of the *Phoebe zhennan* seedlings, and calculate the height-to-diameter ratio; When the height-to-diameter ratio of the *Machilus chinensis* seedlings is >80 and ≤100, the trunk is cut off to obtain truncated seedlings; when the height-to-diameter ratio of the *Machilus chinensis* seedlings is ≤80, the terminal bud is pinched off to obtain pinched seedlings. The trunk height of the cut-off seedling is equal to the ground diameter × 80, and the bare trunk area is 5-8cm below the cut. The bare trunk area has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth node and contains at least 3 growth leaves. Quantitative pruning is carried out on the aforementioned cut-off or pinched-off seedlings, with the amount of pruning controlled to 1 / 2 to 2 / 3 of the total number of branches and leaves of the plant after cut-off or pinching. Once the dominant apical branch appears, prune all other sprouting branches on the bare trunk area in one go.

2. The method for treating *Phoebe zhennan* seedlings according to claim 1, characterized in that, The diameter at ground level of the *Phoebe zhennan* seedlings is 1.5-2.5 cm.

3. The method for treating *Phoebe zhennan* seedlings according to claim 1, characterized in that, The condition (2) is: no growth nodes, containing 3-5 growing leaves.

4. The method for treating *Phoebe zhennan* seedlings according to claim 1, characterized in that, The condition (1) is: it contains at least one growth node and at least one growth leaf.

5. The method for treating *Phoebe zhennan* seedlings according to claim 1, characterized in that, During quantitative pruning, the focus is on removing inner branches, overlapping branches, diseased and insect-infested branches, and weak branches in the lower part of the canopy, while shortening the remaining lateral branches.

6. A cultivation model for *Phoebe zhennan*, comprising a tree-like structure, said tree-like structure including a truncated main trunk, characterized in that, The area below the cut of the main trunk is a dry zone; The height of the truncated main trunk is equal to the ground diameter × 80. The bare section has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth nodes and contains 3-5 growth leaves. After the apical dominance of the *Machilus chinensis* cultivation model is observed, the bare trunk area contains only one apical dominant branch.

7. The *Machilus chinensis* cultivation model according to claim 6, characterized in that, The height-to-diameter ratio of the main trunk before pruning is greater than 80 and less than or equal to 100.

8. A type of Phoebe bournei stem-cutting seedling, characterized in that, The seedlings in the nursery of *Phoebe zhennan* are subjected to trunk cutting or pinching treatment; the trunk height of the cut seedling is equal to the ground diameter × 80, and the bare trunk area is 5-8cm below the cut; the bare trunk area has no lateral branches and meets the following conditions (1) or (2): (1) contains at least one growth node; (2) has no growth node and contains at least 3 growth leaves; The amount of branches and leaves pruned for the cut-off or pinched-off seedlings is 1 / 2 to 2 / 3 of the amount of branches and leaves of the nursery seedlings after the cut-off or pinching-off.

9. The *Phoebe zhennan* seedling according to claim 8, characterized in that, The height-to-diameter ratio of the *Phoebe zhennan* seedlings in the nursery is >80 and ≤100.

10. The method for treating *Phoebe zhennan* seedlings according to any one of claims 1-5, the cultivation model of *Phoebe zhennan* according to claim 6 or 7, or the application of the *Phoebe zhennan* pruning seedlings according to claim 8 or 9 in *Phoebe zhennan* afforestation.

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