A root section treatment-based asexual propagation method of picrasma quassioides

Abstract

The application discloses a Picrasma quassioides asexual propagation method based on root section treatment, relates to the technical field of tree asexual propagation, and adopts a microneedle rolling device to perform one-way rolling on a flat cutting surface at a morphological upper end of a root section to form a parallel microcrack layer, different growth requirements of the morphological upper end and a morphological lower end of the root section are respectively coated with an induction treatment solution, the upper end is coated with a treatment solution containing a cell division factor and an auxin polar transport inhibitor to directionally promote sprouting and block disorderly transport of the auxin polarity, and the lower end is coated with a treatment solution containing an auxin and a browning inhibitor to directionally promote root growth and inhibit browning of the cutting surface. The application constructs the parallel microcrack layer through the microneedle rolling at the upper end of the root section, effectively improves cutting surface air-conducting porosity, optimizes hormone adsorption and penetration effect, and accelerates the differentiation starting speed of sprout primordia. In combination with the differential and accurate coating treatment of the two ends of the root section, the zonal regulation of directionally promoting sprouting at the upper end and directionally promoting root growth at the lower end is realized, the problem of disorderly growth polarity of the root section is completely avoided, and the orderliness of growth and development of the root section is ensured.

Description

Technical Field

[0001] This invention relates to the field of asexual reproduction technology for forest trees, and in particular to a method for asexual reproduction of *Mallotus quinquefolia* based on root segment treatment. Background Technology

[0002] The Chinese tallow tree (Quercus mongolica) is an excellent native tree species with both medicinal and ecological value, and it is widely used in pest and disease control, ecological greening, and pharmaceutical production. Currently, the propagation of Chinese tallow tree seedlings mainly relies on asexual reproduction through root cuttings, which can stably preserve the superior traits of the mother plant and avoid the problem of trait separation in seed propagation.

[0003] Existing root cutting propagation techniques for *Palatinate* have numerous technical shortcomings, limiting seedling survival rates and seedling quality. Traditional propagation methods often involve soaking the entire root segment in hormones, which fails to precisely control the polarity of root growth, easily leading to disordered growth where roots develop at the top while buds sprout at the bottom, significantly reducing seedling survival rates. Conventional seedling cultivation methods often maintain seedbed humidity through full film covering, which easily results in excessive humidity and insufficient aeration at the top of the root segment, causing cut surface rot, pathogen growth, and other problems, leading to an overall high disease incidence rate.

[0004] Meanwhile, existing seedbeds rely solely on capillary action of the substrate for water transport, resulting in poor stability of interlayer water transfer. Humidity gradients are easily affected by ambient temperature and ventilation conditions, making it difficult to maintain a suitable growth environment for root segment rooting and sprouting over the long term. Conventional root segment cut surface treatment methods are relatively simple, with insufficient perforated structure, poor hormone absorption efficiency, and poor aeration and ventilation properties. This leads to slow differentiation of root and shoot primordia, a long seedling cycle, and uneven seedling growth, making it difficult to meet the production needs of large-scale, standardized seedling cultivation. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for the asexual propagation of *Mallotus purpurea* based on root segment treatment. The technical solution is as follows:

[0006] A method for asexual propagation of *Mallotus dahurica* based on root segment treatment includes the following steps:

[0007] Step 1: Collect the roots of the Chinese tallow tree, prune them into root segments of a set length, distinguish the morphological polarity of the root segments, and grade them according to their thickness.

[0008] Step 2: Use a microneedle rolling device to unidirectionally roll the flat section of the upper morphological end of the root segment to form a parallel microcrack layer. Induction treatment solution is applied to the upper and lower morphological ends of the root segment according to their different growth requirements. The upper end is treated with a treatment solution containing cytokinin and auxin polar transport inhibitor to promote shoots in a targeted manner and block the disordered polar transport of auxin. The lower end is treated with a treatment solution containing auxin and anti-browning agent to promote root growth in a targeted manner and inhibit browning of the cut surface.

[0009] Step 3: Construct a seedling bed with a vertical humidity gradient consisting of multiple layers of substrate, relying on capillary action to form a vertical humidity gradient with increasing water content and relative humidity from top to bottom; biodegradable moisture-conducting fiber bundles are buried at equal intervals along the vertical direction in the seedling bed, with the lower end of the fiber bundles extending into the water storage layer and the upper end reaching the lower edge of the planting layer, so as to enhance the stability and response speed of water transfer between layers.

[0010] Step 4: Insert the differentiated induced root segments into the seedbed vertically according to fixed polarity and depth, so that the upper morphological end of the root segment is in the low-humidity planting area of ​​the seedbed and the lower morphological end is in the high-humidity moisture-conducting area of ​​the seedbed.

[0011] Step 5: Without covering with plastic film, regulate the directional sprouting and rooting of root segments through temperature, light, layered watering and antibacterial management;

[0012] Step 6: After the seedlings reach the set growth standards, harden them off by gradually reducing humidity and ventilating them, and finally transplant them to their final location.

[0013] Optionally, in step 1, the collected roots are trimmed into 4cm-5cm root segments. The upper morphological end of the root segment is trimmed horizontally, and the lower morphological end is trimmed at an angle. The root segments are divided into four grades according to their thickness: Grade 1 root segments have a thickness of 0.7cm-1.2cm, Grade 2 root segments have a thickness of 0.4cm-0.6cm, Grade 3 root segments have a thickness of 0.3cm-0.39cm, and Grade 4 root segments have a thickness of 0.2cm-0.29cm. After grading, the root segments are rinsed with clean water and the surface moisture is absorbed with absorbent paper before use.

[0014] Optionally, in step 2, the morphological upper end specific induction treatment solution is a semi-solid agar gel system containing 50 mg / L of 6-benzylaminopurine, 20 μmol / L of N-1-naphthyl-o-carbamoylbenzoic acid, and 0.3% by mass of agar powder; the morphological lower end specific induction treatment solution is an aqueous solution system containing 300 mg / L of indolebutyric acid and 1% by mass of polyvinylpyrrolidone anti-browning agent.

[0015] Optionally, in step 2, the induction treatment solution is applied in a partitioned manner: the upper induction treatment solution is applied only to the flat section at the upper morphological end of the root segment and the annular area 0.5 cm below the flat section, and the lower induction treatment solution is applied only to the oblique section at the lower morphological end of the root segment; after the coating is completed, the root segment is air-dried at room temperature for 10-15 minutes until the gel solidifies and forms a protective film on the cut surface; the microcrack layer formed by microneedle rolling is located in the central area of ​​the flat section, and the rolling direction is perpendicular to the long axis of the root segment. After rolling, the air-conducting porosity of the cut surface is increased by 20-30%.

[0016] Optionally, in step 3, the vertical humidity gradient seedbed adopts a three-layer substrate layered paving structure, consisting of a water storage layer, a moisture-wicking layer, and a planting layer from bottom to top. The water storage layer is a mixture of coarse river sand and water-absorbing resin at a mass ratio of 100:1; the moisture-wicking layer is a mixture of peat moss and perlite at a volume ratio of 3:1; and the planting layer is a mixture of fine river sand and vermiculite at a volume ratio of 1:1. The biodegradable moisture-wicking fiber bundles are made of polylactic acid fibers twisted together, with a diameter of 2-2.3 mm, and a burial density of [missing information - likely a density value] per 100 cm³. 2 The seedbed area is 4-6 bundles, and the degradation cycle of the fiber bundles is 90-120 days. After the seedlings are transplanted, they gradually decompose into organic nutrients.

[0017] Optionally, the thickness and humidity parameters of the three substrate layers are as follows: water storage layer thickness 3.5cm-4cm, relative humidity 95-100%; moisture-wicking layer thickness 5.5cm-6cm, relative humidity 70-80%; planting layer thickness 3-3.5cm, relative humidity 40-50%; each substrate layer forms a stable vertical humidity gradient from top to bottom through capillary water transport and fiber bundle-assisted water conduction.

[0018] Optionally, in step 4, the depth of the holes for cutting in the seedbed is 3.5cm-4cm, the spacing between cuttings is 4cm-4.5cm, and the row spacing is 12cm-13cm. After the root segments are vertically inserted, the upper morphological end is flush with or 2mm below the surface of the planting layer, and the lower morphological end is obliquely cut at the middle and upper part of the moisture-wicking layer. After insertion, the substrate around the root segment in the planting layer is compacted to complete polarity fixation.

[0019] Optionally, in step 5, the temperature is controlled at 22℃-26℃ during the day and 16℃-20℃ at night; the light control is divided into two stages: for the first 15 days after cutting, the cutting is completely dark and shaded; from the 16th day after cutting, the intensity of diffused light is gradually increased to 2000 Lux, and the daily light duration is fixed at 8 hours.

[0020] Optionally, in step 5, water management adopts a bottom-level targeted water replenishment mode, which only replenishes water to the seedbed water storage layer to maintain the water storage layer saturated and the surface of the planting layer dry and not white; antibacterial management involves injecting a 1000-fold diluted carbendazim solution into the bottom of the seedbed every 7 days to complete the overall antibacterial treatment of the substrate.

[0021] Optionally, in step 6, the seedling transplanting standards are seedling height greater than or equal to 8cm, number of true leaves greater than or equal to 3, and root length greater than or equal to 5cm; the seedling hardening operation method is to gradually open the ventilation structure of the seedbed, reduce the water replenishment of the water storage layer, adjust the moisture content of the moisture-conducting layer to 50%±5%, and continue hardening for 7 days; after the seedling hardening is completed, transplant to the field or nutrient pots, and continue to provide shade and moisture retention for the first 10 days after transplanting.

[0022] In summary, the present invention has at least one of the following beneficial technical effects:

[0023] This invention provides a method for asexual propagation of *Mallotus dahurica* based on root segment treatment. By using microneedles to roll and construct parallel microcracks at the upper end of the root segment, the air-conducting porosity of the cut surface is effectively increased, hormone adsorption and penetration are optimized, and the initiation speed of bud primordia differentiation is accelerated. Combined with differentiated and precise coating treatment at both ends of the root segment, it achieves zoned regulation to promote bud growth at the upper end and root growth at the lower end, completely avoiding the problem of disordered polar growth in the root segment and ensuring the orderly growth and development of the root segment.

[0024] This method constructs a multi-layered substrate vertical humidity gradient seedbed, abandoning the traditional film-covered moisturizing model and reducing rot and disease problems caused by high humidity environments at the source. By adding biodegradable moisture-wicking fiber bundles within the seedbed, the efficiency and stability of water transfer between layers are enhanced, resulting in a more balanced and lasting humidity gradient from top to bottom. This precisely adapts to the differentiated growth needs of the lower rooting stage (requiring high humidity) and the upper budding stage (requiring breathable and dry conditions).

[0025] By setting appropriate substrate thickness, humidity, cutting parameters, and temperature, light, water, and fertilizer management systems, the root segment rooting and sprouting environment is further optimized, significantly improving the rooting rate and seedling survival rate. Simultaneously, biodegradable fiber bundle materials are used, which naturally degrade into organic nutrients after seedling cultivation, eliminating the need for subsequent manual cleaning, simplifying the seedling cultivation process, reducing costs, and enabling the stable cultivation of robust, uniform, high-quality *Paspalum notoginseng* seedlings, thus meeting the needs of large-scale seedling production. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating a method for asexual propagation of *Palatinate* based on root segment treatment according to the present invention.

[0027] Figure 2 This is a schematic diagram of the cutting state in a specific embodiment of the present invention. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to the accompanying drawings.

[0029] This invention discloses a method for asexual propagation of *Mallotus purpurea* based on root segment treatment.

[0030] Reference Figure 1 and Figure 2 Example 1: A method for asexual propagation of *Mallotus dahurica* based on root segment treatment, comprising the following steps:

[0031] Step 1: Collect the roots of the Chinese tallow tree, prune them into root segments of a set length, distinguish the morphological polarity of the root segments, and grade them according to their thickness.

[0032] Step 2: Use a microneedle rolling device to unidirectionally roll the flat section of the upper morphological end of the root segment to form a parallel microcrack layer. Induction treatment solution is applied to the upper and lower morphological ends of the root segment according to their different growth requirements. The upper end is treated with a treatment solution containing cytokinin and auxin polar transport inhibitor to promote shoots in a targeted manner and block the disordered polar transport of auxin. The lower end is treated with a treatment solution containing auxin and anti-browning agent to promote root growth in a targeted manner and inhibit browning of the cut surface.

[0033] Step 3: Construct a seedling bed with a vertical humidity gradient consisting of multiple layers of substrate, relying on capillary action to form a vertical humidity gradient with increasing water content and relative humidity from top to bottom; biodegradable moisture-conducting fiber bundles are buried at equal intervals along the vertical direction in the seedling bed, with the lower end of the fiber bundles extending into the water storage layer and the upper end reaching the lower edge of the planting layer, so as to enhance the stability and response speed of water transfer between layers.

[0034] Step 4: Insert the differentiated induced root segments into the seedbed vertically according to fixed polarity and depth, so that the upper morphological end of the root segment is in the low-humidity planting area of ​​the seedbed and the lower morphological end is in the high-humidity moisture-conducting area of ​​the seedbed.

[0035] Step 5: Without covering with plastic film, regulate the directional sprouting and rooting of root segments through temperature, light, layered watering and antibacterial management;

[0036] Step 6: After the seedlings reach the set growth standards, harden them off by gradually reducing humidity and ventilating them, and finally transplant them to their final location.

[0037] By employing the above-mentioned technical solution, *Malus spectabilis* roots are collected and pruned into uniform length segments. These segments are then differentiated based on their inherent morphological and physiological polarities at both ends and graded by thickness to ensure uniformity in subsequent processing. A microneedle rolling device is used to unidirectionally roll the morphologically superior cut surface of the root segments, creating parallel microfissures. The principle behind this physical operation is as follows: after pruning, the cut surface generates numerous damaged cells, but the surface cuticle and dead cell layer hinder oxygen entry and callus differentiation. Microneedle rolling pierces the surface layer at a controlled depth, creating microscopic aeration channels and simultaneously inducing the activation of cell wall peroxidases, promoting the orderly arrangement of callus tissue along the microfissure direction, and providing a structural basis for the subsequent uniform germination of bud primordia.

[0038] Subsequently, different induction treatment solutions were applied to the upper and lower ends of the root segments. The upper induction treatment solution contained cytokinin and an auxin polar transport inhibitor. Cytokinin stimulates the initiation of shoot primordia, while the auxin polar transport inhibitor N-1-naphthyl-o-carbamoylbenzoic acid blocks the transport of endogenous auxin from the upper to the lower end, causing auxin to temporarily accumulate in the upper region and further enhancing the shoot differentiation signal. The lower induction treatment solution contained only auxin-like substances and an anti-browning agent. The auxin indolebutyric acid induces root primordia formation, while the anti-browning agent polyvinylpyrrolidone (PVP) complexes with phenolic substances exuded from the cut surface, preventing polyphenol oxidase from catalyzing the production of melanin, thereby maintaining cell viability on the cut surface. The two treatment solutions were applied separately and air-dried to form a film, creating physical isolation and preventing cross-diffusion.

[0039] A vertical humidity gradient seedbed is constructed. The seedbed consists of three substrate layers: a bottom water-retaining layer with high water holding capacity, a middle moisture-guiding layer that transports water upwards through capillary pores, and an upper planting layer that remains relatively dry. On this basis, biodegradable polylactic acid (PLA) fiber bundles are buried at equal intervals along the vertical direction. The lower end of the fiber bundle extends into the water-retaining layer, and the upper end reaches the lower edge of the planting layer. Its mechanism is to utilize the wicking effect of the fiber bundles to enhance the stability of water transport between layers. Even if the substrate experiences local breakage due to sedimentation or evaporation, the fiber bundles can still maintain a continuous water supply, thus maintaining a stable gradient of increasing moisture content from top to bottom.

[0040] The treated root segments were vertically inserted according to polarity, with the morphological upper end in the dry planting layer and the morphological lower end in the moist wicking layer. The low-humidity environment at the upper end inhibited pathogen growth and stimulated the buds to germinate due to moisture requirements, while the high-humidity environment at the lower end met the water needs of the root primordia and prevented the cut surface from losing water and dying. Management was carried out without covering with plastic film, through diurnal temperature variation, staggered light exposure, bottom watering, and periodic bottom irrigation with pesticides. Bottom watering forced the lower end of the root segment to actively extend towards the moist area, strengthening gravitropism. Once the seedlings reached the required size, the substrate moisture was gradually reduced and ventilation increased to complete hardening-off before transplanting.

[0041] In Example 2, in step 1, the collected roots are pruned into root segments of 4cm-5cm. The upper morphological end of the root segment is pruned horizontally, and the lower morphological end is pruned at an angle. The root segments are divided into four grades according to their thickness: Grade 1 root segments have a thickness of 0.7cm-1.2cm, Grade 2 root segments have a thickness of 0.4cm-0.6cm, Grade 3 root segments have a thickness of 0.3cm-0.39cm, and Grade 4 root segments have a thickness of 0.2cm-0.29cm. After grading, the root segments are rinsed with clean water and the surface moisture is absorbed with absorbent paper before use.

[0042] By adopting the above technical solution, the root segment length is limited to 4cm to 5cm. This length range is based on two principles: if it is too short, the carbohydrates stored in the root segment will be insufficient to support the simultaneous differentiation of buds and roots; if it is too long, the upper part will easily wilt due to water loss during cutting, and the lower part will be too far from the water storage layer, resulting in insufficient capillary water supply. Morphologically, the upper part is cut horizontally to form a smooth callus surface, which facilitates even rolling of microneedles and concentrated bud sprouting. Morphologically, the lower part is cut at an angle to increase the cut surface area, improve the contact surface with the substrate, and guide the new roots to grow obliquely downwards, avoiding hard contact with the bottom of the seedbed when they grow vertically downwards.

[0043] Root segments were graded into four levels based on thickness, from level 1 (0.7-1.2 cm) to level 4 (0.2-0.29 cm). The grading principle lies in the significant differences in the phloem-to-xylem ratio, starch reserves, and endogenous hormone levels among root segments of different thicknesses. Grading allows for targeted adjustments to the application amount of subsequent treatment solutions or the pressure of microneedle rolling to ensure uniform germination across all grades. After grading, the roots were rinsed with clean water and dried to remove impurities and inhibitory substances from the soil, while also preventing surface moisture from diluting the treatment solution concentration.

[0044] In Example 3, in step 2, the morphological upper end specific induction treatment solution is a semi-solid agar gel system containing 50 mg / L of 6-benzylaminopurine, 20 μmol / L of N-1-naphthyl-o-carbamoylbenzoic acid, and 0.3% by mass of agar powder; the morphological lower end specific induction treatment solution is an aqueous solution system containing 300 mg / L of indolebutyric acid and 1% by mass of polyvinylpyrrolidone anti-browning agent.

[0045] By adopting the above technical solution, the upper induction treatment solution is a semi-solid agar gel system. Agar powder content of 0.3% by mass provides the gel with moderate viscosity at room temperature, allowing it to adhere to the cut surface without dripping after coating, forming a transparent film approximately 0.1 mm thick after air drying. This film serves three purposes: first, it acts as a physical barrier to prevent the diffusion of hormones from the coated area to non-target areas; second, it keeps the cut surface moist, preventing excessive water loss and cell death during air drying of the microcracked layer; third, the water in the gel can slowly supply the cells on the cut surface, promoting callus swelling. A 6-benzylaminopurine concentration of 50 mg / L is the threshold determined through gradient experiments. Below this concentration, the bud induction rate decreases significantly, while above this concentration, it easily leads to clustered but weak buds. The selection of N-1-naphthyl-o-carbamoylbenzoic acid concentration of 20 μmol / L is based on the fact that this concentration can effectively inhibit the transport of auxin from the base to the tip through PIN protein without inhibiting cytokinin signaling, thereby increasing the endogenous indoleacetic acid content in the upper region of the root segment by about 1.8 times, which simulates the hormonal environment of the apical meristem.

[0046] The lower induction treatment solution is an aqueous solution, free of agar, because the lower oblique section does not require film protection; instead, it needs rapid absorption. An indolebutyric acid concentration of 300 mg / L is a safe root-promoting concentration below the half-inhibition concentration. Excessive indolebutyric acid can induce excessive callus proliferation, thus inhibiting root primordia differentiation. When polyvinylpyrrolidone (PVP) accounts for 1% by mass, its amide groups can form hydrogen-bonded complexes with phenolic substances overflowing from the cut surface, preventing the phenols from being oxidized to quinone-like brown substances by polyphenol oxidase, thereby maintaining the light yellow color of the cut surface and preserving cell division activity.

[0047] In Example 4, in step 2, the induction treatment solution is applied in a partitioned manner: the upper induction treatment solution is applied only to the flat section at the upper morphological end of the root segment and the annular area 0.5 cm below the flat section, while the lower induction treatment solution is applied only to the oblique section at the lower morphological end of the root segment. After coating, the root segment is air-dried at room temperature for 10-15 minutes until the gel solidifies and forms a protective film on the cut surface. The microcrack layer formed by microneedle rolling is located in the central area of ​​the flat section, and the rolling direction is perpendicular to the long axis of the root segment. After rolling, the air-conducting porosity of the cut surface increases by 20-30%.

[0048] By employing the above technical solution, the coating process is strictly zoned: the upper treatment solution is applied only to the flat cut surface and a 0.5cm annular area below it. This 0.5cm distance is determined based on the longitudinal conduction characteristics of the root cambium; within this range, auxin polar transport inhibitors are sufficient to block the downward flow of endogenous auxin, while beyond 0.5cm, the inhibitor concentration is diluted, leading to a decrease in effectiveness. The lower treatment solution is applied only to the oblique cut surface to prevent indolebutyric acid (IBA) from diffusing into the upper area and causing unintended rooting. The two brushes are strictly separated to prevent cross-contamination and the resulting polarity disorder of rooting at the upper end and sprouting at the lower end.

[0049] After coating, allow the material to air dry for 10 to 15 minutes. The key to controlling this time is ensuring the gel fully cures without excessive water loss. Incomplete curing will cause the membrane to be rubbed off by the matrix during insertion; excessive water loss will cause the membrane to become brittle and lose its insulating function. Microneedle rolling is performed before coating. The microneedles used for rolling are 0.25 mm long, a depth that penetrates the cork layer of the root segment's periderm without damaging the phloem parenchyma cells. The needle density is 20 needles per square centimeter, spaced approximately 0.5 mm apart, forming a uniform array of microfissures. The rolling direction is perpendicular to the long axis of the root segment. The principle is that perpendicular microfissures induce callus cells to divide and form an arrangement perpendicular to the root axis. This arrangement facilitates the outward protrusion of subsequent shoot primordia from the microfissures, rather than them sinking into the tissue. After rolling, the aeration porosity increases by 20% to 30%. This increase is determined through microscopic image analysis: insufficient porosity limits oxygen supply and slows callus growth; excessive porosity accelerates water loss from the cut surface, which is detrimental.

[0050] In Example 5, step 3, the vertical humidity gradient seedbed adopts a three-layer substrate layered paving structure, consisting of a water storage layer, a moisture-wicking layer, and a planting layer from bottom to top. The water storage layer is a mixture of coarse river sand and water-absorbing resin at a mass ratio of 100:1; the moisture-wicking layer is a mixture of peat moss and perlite at a volume ratio of 3:1; and the planting layer is a mixture of fine river sand and vermiculite at a volume ratio of 1:1. The biodegradable moisture-wicking fiber bundles are made of polylactic acid fibers twisted together, with a diameter of 2-2.3 mm, and a burial density of [missing information - likely a density value] per 100 cm³. 2 The seedbed area is 4-6 bundles, and the degradation cycle of the fiber bundles is 90-120 days. After the seedlings are transplanted, they gradually decompose into organic nutrients.

[0051] By employing the above technical solution, the coating process is strictly zoned: the upper treatment solution is applied only to the flat cut surface and a 0.5cm annular area below it. This 0.5cm distance is determined based on the longitudinal conduction characteristics of the root cambium; within this range, auxin polar transport inhibitors are sufficient to block the downward flow of endogenous auxin, while beyond 0.5cm, the inhibitor concentration is diluted, leading to a decrease in effectiveness. The lower treatment solution is applied only to the oblique cut surface to prevent indolebutyric acid (IBA) from diffusing into the upper area and causing unintended rooting. The two brushes are strictly separated to prevent cross-contamination and the resulting polarity disorder of rooting at the upper end and sprouting at the lower end.

[0052] After coating, allow the material to air dry for 10 to 15 minutes. The key to controlling this time is ensuring the gel fully cures without excessive water loss. Incomplete curing will cause the membrane to be rubbed off by the matrix during insertion; excessive water loss will cause the membrane to become brittle and lose its insulating function. Microneedle rolling is performed before coating. The microneedles used for rolling are 0.25 mm long, a depth that penetrates the cork layer of the root segment's periderm without damaging the phloem parenchyma cells. The needle density is 20 needles per square centimeter, spaced approximately 0.5 mm apart, forming a uniform array of microfissures. The rolling direction is perpendicular to the long axis of the root segment. The principle is that perpendicular microfissures induce callus cells to divide and form an arrangement perpendicular to the root axis. This arrangement facilitates the outward protrusion of subsequent shoot primordia from the microfissures, rather than them sinking into the tissue. After rolling, the aeration porosity increases by 20% to 30%. This increase is determined through microscopic image analysis: insufficient porosity limits oxygen supply and slows callus growth; excessive porosity accelerates water loss from the cut surface, which is detrimental.

[0053] Example 6: The thickness and humidity parameters of the three substrate layers are as follows: the water storage layer has a thickness of 3.5cm-4cm and a relative humidity of 95-100%; the moisture-wicking layer has a thickness of 5.5cm-6cm and a relative humidity of 70-80%; and the planting layer has a thickness of 3-3.5cm and a relative humidity of 40-50%. Each substrate layer forms a stable vertical humidity gradient from top to bottom through capillary water transport and fiber bundle-assisted water conduction.

[0054] By adopting the above technical solution, the thickness of the water storage layer is 3.5 to 4 cm. This thickness ensures that the water column pressure of at least 2.5 cm is sufficient to drive capillary rise, while providing sufficient space for the water-absorbing resin to expand. If the thickness is less than 3.5 cm, the resin may compress the upper substrate and damage the pore structure after absorbing water and expanding; if it is greater than 4 cm, the seedbed will be too high, making operation inconvenient. The relative humidity of the water storage layer is 95% to 100%, which is actually saturated but without free water. Under this humidity, even if the lower end of the root segment occasionally extends into this layer, it will not rot due to lack of oxygen, because the large pores of the coarse river sand still maintain gas exchange channels.

[0055] The moisture-wicking layer is 5.5 to 6 cm thick. This thickness is the effective height for capillary ascent of peat soil; if it exceeds 6 cm, the upper planting layer will not be able to obtain enough moisture. The relative humidity of the moisture-wicking layer is 70% to 80%. Within this humidity range, the pore water in the peat soil is in a meniscus state, which can maintain the continuous conduction of liquid water without blocking the pore gas channels due to water saturation.

[0056] The planting layer thickness is 3 to 3.5 cm. If the thickness is less than 3 cm, the upper part of the root segment may become accidentally damp due to excessive proximity to the moisture-wicking layer; if it is greater than 3.5 cm, the lower part of the root segment, when the total length is 4 to 5 cm, will not be able to reach the upper part of the moisture-wicking layer. The relative humidity of the planting layer is 40% to 50%, which was determined by actual measurement with a thermocouple hygrometer: below 40%, the buds are prone to drying out, and above 50%, the surface is prone to mold growth. The gradient between the layers is not established by physical barriers, but by the natural balance of capillary forces. The auxiliary water-conducting effect of the fiber bundles reduces the sensitivity of this gradient to temperature fluctuations and localized substrate drying. Experiments show that in seedbeds with fiber bundles, the humidity of the planting layer only decreases by 5% to 8% after watering is stopped for 48 hours, while the humidity of the control group without fiber bundles decreases by 15% to 20%.

[0057] In Example 7, in step 4, the depth of the holes for cutting in the seedbed is 3.5cm-4cm, the spacing between cuttings is 4cm-4.5cm, and the row spacing is 12cm-13cm. After the root segments are vertically inserted, the upper morphological end is flush with or 2mm below the surface of the planting layer, and the lower morphological end is obliquely cut and located in the upper part of the moisture-wicking layer. After insertion, the substrate around the root segment in the planting layer is compacted to complete polarity fixation.

[0058] By adopting the above technical solution, the hole depth is 3.5 to 4 cm. This depth is slightly shallower than the root segment length of 4 to 5 cm, so that the upper end of the root segment is just level with or slightly lower than the surface of the planting layer after insertion. If the hole depth is greater than the root segment length, the upper end will be buried too deep in the substrate, making it difficult for the buds to break through the surface and prone to rotting; if the hole depth is less than the root segment length minus 2 mm, the upper end will protrude too much and lose water too quickly when exposed to air. The design of a plant spacing of 4 to 4.5 cm and a row spacing of 12 to 13 cm is based on the fact that the leaves of the early-stage *Paspalum notatum* seedlings are small, and this density allows them to be cultivated in the seedbed for 60 to 70 days without shading each other, while the roots will not become excessively entangled when expanding laterally in the moisture-wicking layer.

[0059] After the root segment is inserted, its upper morphological end should be no more than 2 mm below the surface of the planting layer. The principle behind this slight indentation is that it allows condensed water vapor to accumulate in the microenvironment, creating a locally humid microclimate that promotes bud break. Simultaneously, the indentation prevents direct impact from water droplets generated during watering or spraying. The lower morphological end, cut at an angle, should be located in the upper-middle part of the moisture-wicking layer, specifically about 1.5 to 2 cm from the top surface. This position ensures that the lower end can contact the substrate with 70% to 80% humidity without directly sinking into the saturated area of ​​the water-retaining layer, which could lead to oxygen deficiency. When compacting the substrate around the root segment, the pressure should be such that a light press leaves a fingerprint about 1 mm deep on the substrate surface. Too loose a pressure will create gaps between the root segment and the substrate, interrupting water transport; too firm a pressure will damage the cortical cells of the root segment.

[0060] In Example 8, step 5, the temperature is controlled at 22℃-26℃ during the day and 16℃-20℃ at night; the light control is divided into two stages: for the first 15 days after cutting, the cutting is completely dark and shaded; from the 16th day after cutting, the intensity of diffused light is gradually increased to 2000 Lux, and the daily light duration is fixed at 8 hours.

[0061] By adopting the above technical solution, temperature control employs diurnal temperature variation, with daytime temperatures ranging from 22 to 26°C and nighttime temperatures from 16 to 20°C. The principle behind this temperature variation is that higher daytime temperatures promote photosynthesis and bud elongation, while lower nighttime temperatures reduce respiration. Simultaneously, the diurnal temperature difference stimulates fluctuations in the endogenous abscisic acid levels in the root segments, helping to break dormancy. Actual measurements show that under constant temperature conditions, the root segment germination rate decreases by approximately 15%, and the abnormal phenomenon of buds failing to develop roots is more likely to occur.

[0062] Light regulation is divided into two stages. The first stage involves complete darkness for the first 15 days after cutting. Under dark conditions, the activity of phenylalanine ammonia-lyase in the lower part of the root segment decreases, reducing lignin synthesis and helping the callus tissue maintain its meristematic state. Simultaneously, darkness inhibits premature differentiation of chloroplasts in the upper part of the root, prioritizing the supply of limited nutrients to root primordia development. The second stage begins on the 16th day with a gradual increase in diffused light to 2000 Lux. 2000 Lux is approximately 2.5 times the light compensation point for *Papilio scandens* seedlings, meeting photosynthetic needs without causing photoinhibition. This gradual increase lasts 5 to 7 days, allowing newly emerging buds to gradually adapt to the light environment and avoiding photo-oxidative damage caused by sudden strong light. Eight hours of light per day simulates the length of autumn days; this photocycle induces compact internode structures in seedlings and prevents excessive growth.

[0063] In Example 9, step 5, water management adopts a bottom-level targeted water replenishment mode, which only replenishes water to the seedbed water storage layer to maintain the water storage layer saturation and the surface of the planting layer dry and not white; antibacterial management involves injecting a 1000-fold carbendazim solution into the bottom of the seedbed every 7 days to complete the overall antibacterial treatment of the substrate.

[0064] By adopting the above technical solution, the core of the bottom-layer targeted watering mode lies in utilizing the hydrotropism of plant roots to drive growth. Traditional top-down watering causes water to seep into the surface of the planting layer, resulting in excessive humidity at the upper part of the root segment and triggering stem rot. However, with bottom-layer watering, water is transported upward from the water storage layer through capillary action and wicking, keeping the surface of the planting layer dry at all times. The upper part of the root segment is exposed to dry air, making it difficult for pathogen spores to germinate. At the same time, the lower part of the root segment senses the high humidity gradient below and will actively extend the root system downward, forming a deep root structure, resulting in stronger drought resistance after transplanting. The watering standard of "dry and non-whitish surface of the planting layer" is a judgment criterion summarized from experience: a whitish surface indicates that the moisture content of the fine river sand is less than 35%, at which point bud growth is hindered; a moist and reflective surface indicates that the moisture content exceeds 55%, making the plant susceptible to disease.

[0065] Antimicrobial management involves injecting a 1000-fold dilution of carbendazim solution into the bottom of the seedbed every 7 days. The principle of bottom injection is that the solution permeates the water-retaining and moisture-wicking layers from bottom to top, directly acting on the lower cut surface of the root segment—the most vulnerable area for pathogens. Traditional foliar spraying primarily covers the surface of the planting layer, offering poor effectiveness against deeper pathogens. A 1000-fold dilution of carbendazim represents a balance between antimicrobial and phytotoxic concentrations; concentrations above 500 times inhibit cell division at the lower root segment, while concentrations below 2000 times result in less than 70% inhibition of Fusarium and Pythium fungi. The frequency of injection every 7 days matches the half-life of carbendazim in the substrate, ensuring sustained efficacy throughout the germination period (approximately 45 days).

[0066] In Example 10, step 6, the seedling transplanting standards are seedling height greater than or equal to 8cm, number of true leaves greater than or equal to 3, and root length greater than or equal to 5cm; the seedling hardening operation method is to gradually open the ventilation structure of the seedbed, reduce the water replenishment of the water storage layer, adjust the moisture content of the moisture-conducting layer to 50%±5%, and continue hardening for 7 days; after the seedling hardening is completed, transplant to the field or nutrient pots, and continue to provide shade and moisture retention for the first 10 days after transplanting.

[0067] By adopting the above technical solution, the transplanting standards for seedlings are set as follows: seedling height ≥ 8cm, number of true leaves ≥ 3, and root length ≥ 5cm. A seedling height of 8cm corresponds to the point where the *Palatinate* seedling transitions from heterotrophic to autotrophic and possesses a certain photosynthetic capacity; 3 true leaves indicate a leaf area index sufficient to support post-transplant transpiration; and a root length of 5cm signifies the presence of at least first-order lateral roots and abundant fibrous roots, enabling effective water absorption. Transplanting before reaching these standards results in a prolonged seedling recovery period and a high mortality rate.

[0068] The core of hardening-off seedlings is to gradually reduce the moisture content of the moisture-wicking layer to 50% ± 5%. During this process, the substrate water potential decreases from approximately -10 kPa to -50 kPa. This water potential gradient stimulates the root system to produce more root hairs and lateral roots, while simultaneously thickening the leaf cuticle and reducing stomatal density. Continuing hardening-off for 7 days is the shortest time required to complete these adaptive changes. During hardening-off, ventilation structures are gradually opened to increase airflow, allowing seedlings to adapt to the wind conditions of the field in advance, which can increase the lignin content of the stems by approximately 30%.

[0069] For the first 10 days after transplanting, provide shade and maintain moisture. A 50% shading rate can reduce leaf transpiration by about 60%, while also preventing strong light from inhibiting the repair of photosynthetic system II. Spray water twice a day, morning and evening, to keep the substrate moist, but avoid waterlogging, as some fibrous roots will inevitably be damaged during transplanting, and waterlogged conditions can easily lead to root rot. After 10 days, once the root system has established an effective connection with the new substrate, gradually remove the shading net and transition to regular care.

[0070] The following specific embodiments illustrate the implementation principle of the present invention:

[0071] The procedure was carried out inside a glass greenhouse at a plant tissue culture center in the province.

[0072] Step 1: Root segment collection and grading;

[0073] Select healthy, disease-free, 3-year-old *Dracaena sanderiana* plants and harvest the taproot and lateral roots during transplanting. Trim the roots into 4.5cm long segments, morphologically cutting the upper end horizontally and the lower end at a 45° angle. Classify the roots into four grades based on thickness: Grade 1 (0.9cm diameter), Grade 2 (0.5cm diameter), Grade 3 (0.35cm diameter), and Grade 4 (0.25cm diameter). Take 100 segments from each grade. Rinse three times with clean water, place on clean absorbent paper and gently press to absorb surface moisture, then allow to air dry at room temperature for 2 minutes.

[0074] Step 2: Microneedle rolling and differential coating at both ends;

[0075] Using a medical-grade microneedle roller, with a needle length of 0.25mm and a needle density of 20 needles / cm². 2 The morphological upper surface of each root segment is subjected to unidirectional rolling, with the rolling direction perpendicular to the long axis of the root segment, and the rolling is performed twice (with a 90-degree rotation after each rolling). After rolling, parallel microcracks with a spacing of about 0.5 mm are formed in the central region of the flat surface, increasing the gas-conducting porosity by about 25%.

[0076] Preparation of the upper treatment solution: Take 50 mg of 6-benzylaminopurine and 20 μmol of N-1-naphthyl-o-carbamoylbenzoic acid, add 0.3 g of agar powder, and dilute to 100 mL with distilled water. Heat to dissolve and then cool to 40 °C for later use.

[0077] Preparation of the lower treatment solution: Take 300 mg indolebutyric acid and 1 g polyvinylpyrrolidone, and dilute to 100 mL with distilled water. Stir and dissolve at room temperature.

[0078] Using a clean brush, apply the upper treatment solution only to the flat surface of the root section and the 0.5cm ring area below it; then use another brush to apply the lower treatment solution only to the oblique surface. After applying the solution to each root section, place it on a tray and air dry at room temperature for 12 minutes, until the upper gel solidifies into a transparent film.

[0079] Step 3: Constructing a vertical humidity gradient seedbed;

[0080] Use a plastic seedling tray that is 100cm long, 50cm wide, and 20cm high, with drainage holes at the bottom.

[0081] Paving: Water storage layer: Mix coarse river sand and water-absorbing resin at a mass ratio of 100:1, lay a 4cm thick layer, and spray water until saturated but without free water.

[0082] Moisture-wicking layer: Mix peat moss and perlite in a volume ratio of 3:1, lay a 6cm thick layer, and adjust the moisture content to 65%.

[0083] Planting layer: Mix fine river sand and vermiculite in a 1:1 volume ratio, spread to a thickness of 3.5cm, and adjust the moisture content to 28%.

[0084] When laying the moisture-wicking layer, biodegradable polylactic acid fiber bundles with a diameter of 2.2 mm are vertically buried. The degradation period is 105 days, and the burial density is 100 cm². 2 5 bundles. Use a thin bamboo skewer to poke holes, insert the fiber bundles vertically, with the lower end penetrating 1cm into the bottom of the water-retaining layer and the upper end flush with the upper surface of the moisture-wicking layer. After laying the planting layer, the upper ends of the fiber bundles will be covered by about 0.5cm.

[0085] Step 4: Cuttings and polarity fixation;

[0086] Using a perforating tool, make holes 3.8 cm deep on the surface of the planting layer at a spacing of 4.2 cm between plants and 12.5 cm between rows. Insert the treated root cuttings vertically into the holes, with the upper morphological end (flat cut end) flush with the surface of the planting layer, allowing a 1 mm margin below the surface. The lower morphological end (slanted cut end) should be positioned above the moisture-wicking layer, approximately 1.8 cm from its top surface. Insert one cutting into each hole, gently pressing the surrounding substrate with your finger to leave a 1 mm deep fingerprint. A total of 400 cuttings were planted in a 0.5 m² seedbed. 2 .

[0087] Step 5: Environmental control and management;

[0088] Temperature: Daytime temperature 24℃±1℃, nighttime temperature 18℃±1℃, daytime and nighttime temperature changes are automatically adjusted by a thermostat.

[0089] Light: Cover with double-layer black shade netting from day 1 to day 15 after cutting, keeping the area completely dark; gradually remove the shade netting from day 16 onwards, increasing the light intensity daily until it reaches 2000 Lux on day 22, and maintain a fixed 8 hours of light per day, using full-spectrum LED lights as the light source.

[0090] Water management: Water is added to the water storage layer only through the side holes at the bottom of the seedbed, once every 2 days, to keep the water storage layer saturated and the surface of the planting layer dry and not white.

[0091] Antibacterial management: Every 7 days, pour in a 1000-fold diluted carbendazim solution through the bottom, at a rate of 2L per square meter.

[0092] Step 6: Hardening off seedlings and transplanting;

[0093] Cuttings as Figure 2 As shown, on the 52nd day after cutting, the seedlings met the transplanting standards: average seedling height 9.2cm, 3.5 true leaves, and root length 6.1cm. Hardening-off process began: gradually opening the ventilation windows on both sides of the seedbed, increasing daily ventilation from 2 hours to 8 hours; simultaneously reducing the water supply to the water storage layer, lowering the moisture content of the moisture-wicking layer from 70% to 52%±3%, for 7 days. After hardening-off, carefully lift the seedlings and transplant them into 10cm×10cm seedling pots with a substrate of garden soil and well-rotted organic fertilizer in a 2:1 volume ratio. For the first 10 days after transplanting, provide 50% shade and spray water twice a day, morning and evening, to keep the soil moist. After 10 days, remove the shade netting and transition to regular management.

[0094] Implementation results statistics:

[0095] A total of 400 cuttings were taken, of which 385 seedlings survived, resulting in an overall seedling survival rate of 96.3%. The survival rates were as follows: Grade 1 cuttings: 98%; Grade 2 cuttings: 97%; Grade 3 cuttings: 96%; Grade 4 cuttings: 94%. The uniformity of sprouting, expressed as the coefficient of variation in seedling height, was 11.2%. The survival rate 30 days after transplanting was 97.4%. The root system was well-developed, with an average of 7.2 lateral roots and 98 fibrous roots.

[0096] Comparative implementation case: Using conventional root cutting propagation technology: Root segments are cut to 4cm in length, with the top cut horizontally and the bottom cut at an angle, without grading; disinfected with 0.5% potassium permanganate for 5 minutes, then soaked in 250ppm ABT1 rooting powder for 30 minutes; inserted into a mixture of ordinary garden soil and river sand (volume ratio 2:1), with a spacing of 5cm × 15cm and a depth of 3cm; watered thoroughly after insertion, and covered with a small transparent plastic film greenhouse to retain moisture; shaded for the first 30 days, then gradually removed; sprayed with 1000 times diluted carbendazim every 10 days; watered as usual.

[0097] Comparative implementation process: 400 root segments (ungraded) from 3-year-old *Melia azedarach* trees were selected and pruned using the same traditional method. The segments were placed in different seedbeds within the same greenhouse and managed for the same duration.

[0098] Comparison Results Statistics

[0099] A total of 302 seedlings were produced, with a seedling survival rate of 75.5%. The coefficient of variation for seedling height was 24.6%. The survival rate 30 days after transplanting was 81.2%. The average number of lateral roots was 3.5, and the average number of fibrous roots was 41. The incidence of diseases (stem rot, root rot) was approximately 18%.

[0100] The specific comparison results are shown in Table 1:

[0101]

[0102] Therefore, this invention significantly improves the seedling rate, uniformity, root quality, and transplant survival rate of asexual propagation of *Paspalum notatum* root segments through innovative technologies such as microneedle rolling, differential induction at both ends, vertical humidity gradient seedbed, and fiber bundle enhanced water conduction. At the same time, it reduces the incidence of diseases, requires no plastic film covering, is easy to operate, and has outstanding substantial progress and industrial applicability.

[0103] The above are all preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for asexual propagation of *Mallotus dahurica* based on root segment treatment, characterized in that, Includes the following steps: Step 1: Collect the roots of the Chinese tallow tree, prune them into root segments of a set length, distinguish the morphological polarity of the root segments, and grade them according to their thickness. Step 2: Use a microneedle rolling device to unidirectionally roll the flat section of the upper morphological end of the root segment to form a parallel microcrack layer. Induction treatment solution is applied to the upper and lower morphological ends of the root segment according to their different growth requirements. The upper end is treated with a treatment solution containing cytokinin and auxin polar transport inhibitor to promote shoots in a targeted manner and block the disordered polar transport of auxin. The lower end is treated with a treatment solution containing auxin and anti-browning agent to promote root growth in a targeted manner and inhibit browning of the cut surface. Step 3: Construct a seedling bed with a vertical humidity gradient consisting of multiple layers of substrate, relying on capillary action to form a vertical humidity gradient with increasing water content and relative humidity from top to bottom; biodegradable moisture-conducting fiber bundles are buried at equal intervals along the vertical direction in the seedling bed, with the lower end of the fiber bundles extending into the water storage layer and the upper end reaching the lower edge of the planting layer, so as to enhance the stability and response speed of water transfer between layers. Step 4: Insert the differentiated induced root segments into the seedbed vertically according to fixed polarity and depth, so that the upper morphological end of the root segment is in the low-humidity planting area of ​​the seedbed and the lower morphological end is in the high-humidity moisture-conducting area of ​​the seedbed. Step 5: Without covering with plastic film, regulate the directional sprouting and rooting of root segments through temperature, light, layered watering and antibacterial management; Step 6: After the seedlings reach the set growth standards, harden them off by gradually reducing humidity and ventilating them, and finally transplant them to their final location.

2. The method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 1, characterized in that: In step 1, the collected roots are trimmed into 4cm-5cm root segments. The upper morphological end of the root segment is trimmed horizontally, and the lower morphological end is trimmed at an angle. The root segments are divided into four grades according to their thickness: Grade 1 root segments have a thickness of 0.7cm-1.2cm, Grade 2 root segments have a thickness of 0.4cm-0.6cm, Grade 3 root segments have a thickness of 0.3cm-0.39cm, and Grade 4 root segments have a thickness of 0.2cm-0.29cm. After grading, the root segments are rinsed with clean water and the surface moisture is absorbed with absorbent paper before use.

3. The method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 2, characterized in that: In step 2, the morphological upper end exclusive induction treatment solution is a semi-solid agar gel system containing 50 mg / L of 6-benzylaminopurine, 20 μmol / L of N-1-naphthyl-o-carbamoylbenzoic acid, and 0.3% by mass of agar powder; the morphological lower end exclusive induction treatment solution is an aqueous solution system containing 300 mg / L of indolebutyric acid and 1% by mass of polyvinylpyrrolidone anti-browning agent.

4. The method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 3, characterized in that: In step 2, the induction treatment solution is applied in a partitioned manner: the upper induction treatment solution is applied only to the flat section at the upper morphological end of the root segment and the annular area 0.5 cm below the flat section, while the lower induction treatment solution is applied only to the oblique section at the lower morphological end of the root segment. After coating, the root segment is air-dried at room temperature for 10-15 minutes until the gel solidifies and forms a protective film on the cut surface. The microcrack layer formed by microneedle rolling is located in the central area of ​​the flat section, and the rolling direction is perpendicular to the long axis of the root segment. After rolling, the air-conducting porosity of the cut surface increases by 20-30%.

5. The method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 4, characterized in that: In step 3, the vertical humidity gradient seedbed adopts a three-layer substrate layering structure, consisting of a water storage layer, a moisture-wicking layer, and a planting layer from bottom to top. The water storage layer is a mixture of coarse river sand and water-absorbing resin at a mass ratio of 100:1; the moisture-wicking layer is a mixture of peat moss and perlite at a volume ratio of 3:1; and the planting layer is a mixture of fine river sand and vermiculite at a volume ratio of 1:

1. The biodegradable moisture-wicking fiber bundles are made of polylactic acid fibers twisted together, with a diameter of 2-2.3 mm, and are laid at a density of [missing information - likely a density of 100 cm²]. 2 The seedbed area is 4-6 bundles, and the degradation cycle of the fiber bundles is 90-120 days. After the seedlings are transplanted, they gradually decompose into organic nutrients.

6. The method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 4, characterized in that: The thickness and humidity parameters of the three substrate layers are as follows: the water storage layer is 3.5cm-4cm thick with a relative humidity of 95-100%; the moisture-wicking layer is 5.5cm-6cm thick with a relative humidity of 70-80%; and the planting layer is 3-3.5cm thick with a relative humidity of 40-50%. Each substrate layer forms a stable vertical humidity gradient from top to bottom through capillary water transport and fiber bundle-assisted water conduction.

7. The method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 4, characterized in that: In step 4, the depth of the holes for cuttings in the seedbed is 3.5cm-4cm, the spacing between cuttings is 4cm-4.5cm, and the row spacing is 12cm-13cm. After the root segments are vertically inserted, the upper morphological end is level with or 2mm below the surface of the planting layer, and the lower morphological end is obliquely cut at the upper part of the moisture-wicking layer. After insertion, the substrate around the root segment in the planting layer is compacted to complete polarity fixation.

8. The method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 7, characterized in that: In step 5, the temperature is controlled at 22℃-26℃ during the day and 16℃-20℃ at night; the light control is divided into two stages: for the first 15 days after cutting, the cutting is completely dark and shaded; from the 16th day after cutting, the intensity of diffused light is gradually increased to 2000 Lux, and the daily light duration is fixed at 8 hours.

9. A method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 8, characterized in that: In step 5, water management adopts a bottom-directed watering mode, which only replenishes water to the water storage layer of the seedbed to maintain the water storage layer saturation and the surface of the planting layer dry and not white; antibacterial management involves pouring a 1000-fold carbendazim solution into the bottom of the seedbed every 7 days to complete the overall antibacterial treatment of the substrate.

10. A method for asexual propagation of *Mallotus dahurica* based on root segment treatment according to claim 9, characterized in that: In step 6, the seedling transplanting standards are seedling height greater than or equal to 8cm, number of true leaves greater than or equal to 3, and root length greater than or equal to 5cm. The seedling hardening operation method is to gradually open the ventilation structure of the seedbed, reduce the water replenishment of the water storage layer, adjust the moisture content of the moisture-conducting layer to 50%±5%, and continue hardening for 7 days. After the seedling hardening is completed, transplant to the field or nutrient pots, and continue to provide shade and moisture retention for the first 10 days after transplanting.

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