A seed soaking method for plinthus radiata seedling by mixing seed with wood ash and soaking with gibberellin

Abstract

The present application belongs to the technical field of forestry, and particularly relates to a seedling raising method of Idesia polycarpa by seed dressing with grasswood ash combined with gibberellin soaking, which comprises the following steps: after seed selection, the seeds are modulated with grasswood ash, and the grasswood ash and the seeds are mixed at a weight ratio of 1:5 to 1:8; a gibberellin solution with a concentration of 100 to 200 mg / L is prepared and used to soak the seeds after seed dressing for 6 to 12 hours; and the treated seeds are sowed in a mixture of sandy soil, mature organic fertilizer and perlite to perform seedling raising management. The mineral nutrients such as potassium, calcium, phosphorus and magnesium in the grasswood ash provide nutrient support for seed germination, and the alkaline characteristics of the grasswood ash change the cell permeability of the seed coat, thereby enhancing the penetration efficiency of the gibberellin into the seed. The two treatments form a synergistic effect of nutrient supply and hormone regulation. According to the present application, the seed germination rate of Idesia polycarpa is increased to more than 90%, the survival rate after transplanting is more than 92%, and the defect of low germination rate caused by single treatment is effectively overcome.

Description

Technical Field

[0001] This invention belongs to the field of forestry technology, specifically a method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin. Background Technology

[0002] As an important woody oilseed tree species, the seeds of *Vernicia fordii* have dormancy characteristics. In conventional seedling cultivation, the seed germination rate is low and the seedlings grow slowly, making it difficult to cultivate high-quality seedlings with well-developed root systems and robust growth. This has become the core obstacle restricting the large-scale propagation of *Vernicia fordii*.

[0003] Common methods for cultivating *Vernicia fordii* seedlings generally employ single nutrient treatment or single hormone treatment, such as using wood ash alone to mix seeds to supplement nutrients or using gibberellin alone to soak seeds to promote germination. However, single treatment methods are difficult to simultaneously meet the dual needs of seed germination and seedling growth.

[0004] Due to incomplete breaking of seed dormancy and uncoordinated nutrient supply to seedlings, germinating seedlings often exhibit weak growth, thin and tall stature, and poor resistance to adverse conditions, making it difficult to guarantee transplant survival rates and failing to meet the requirements for cultivating high-quality seedlings. This has become a key problem that urgently needs to be solved in the current field of *Vernicia fordii* seedling cultivation.

[0005] Therefore, the present invention provides a method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by this invention to solve its technical problem is: a method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin, comprising the following steps:

[0008] Step 1: Seed collection and selection. Select mature *Vernicia fordii* fruits as the seed source. Remove the pulp from the fruits to obtain the seeds. Then, soak the seeds in clean water to remove any floating empty or shriveled seeds and impurities, resulting in plump, uniformly sized, high-quality seeds. Spread the selected seeds out in a well-ventilated, shady place to dry. During the drying process, turn the seeds regularly to ensure that the moisture content drops to a safe storage range of 8% to 12%, preventing mold or decreased viability due to excessive moisture. The purpose of the selection process is to remove poorly developed seeds, providing a consistent raw material base for subsequent seed dressing and soaking treatments.

[0009] Step 2: Obtaining and processing wood ash. Select the ash from fully burned woody plant remains as the raw material for wood ash. Sieve the wood ash through an 80-mesh standard sieve to remove unburned granular charcoal pieces and large impurities, obtaining fine wood ash powder with a delicate texture and uniform composition. Then, place the fine wood ash powder in a drying oven and dry it at a temperature of 105℃ to 110℃ for 2 to 3 hours to completely remove the moisture adsorbed in the wood ash. After drying, remove it and cool it to room temperature. The cooled wood ash powder needs to be sealed and stored to prevent re-absorbing moisture. Wood ash is rich in mineral nutrients such as potassium, calcium, phosphorus, and magnesium, as well as various trace elements. Its alkaline properties can effectively regulate the acid-base environment on the seed surface, creating favorable chemical conditions for seed germination.

[0010] Step 3: Soak and knead the wood ash extract. Add the prepared wood ash powder to deionized water or clean water at a weight ratio of 1:10 to 1:15. Stir thoroughly and let it stand for 2 to 4 hours, stirring every 30 minutes to ensure the mineral nutrients in the wood ash are fully dissolved. After standing, filter through multiple layers of gauze or use natural sedimentation to obtain the supernatant, which is the wood ash extract. Soak the selected and dried seeds in the wood ash extract at a temperature of 20℃ to 25℃ for 4 to 8 hours, stirring slowly during the process to enhance the uniformity of the extract and the seed coat. The process involves contact, allowing the potassium, calcium, phosphorus, magnesium, and other mineral elements and alkaline components in the wood ash to fully act on the seed coat surface, softening the waxy layer and altering the permeability of the seed coat cells. After soaking, the seeds are removed and placed in a plastic basin or cloth bag for manual rubbing. The rubbing should be done with even pressure, similar to washing clothes, for 5 to 10 minutes, effectively removing the waxy layer from the seed coat surface through mechanical friction. After rubbing, the seeds are rinsed 2 to 3 times with clean water to remove residual wood ash and removed waxy debris. Finally, the seeds are drained until they are no longer dripping wet before proceeding to the next step of gibberellin soaking. This liquid extraction combined with rubbing treatment, through the synergistic effect of chemical softening and physical friction, can more thoroughly remove the waxy layer from the seed coat surface of *Vernicia fordii*, significantly enhancing seed coat permeability and creating more favorable conditions for subsequent gibberellin penetration.

[0011] Step 4: Prepare and soak the seeds in the gibberellin solution. Use deionized water as the solvent to prepare a gibberellin solution with a concentration of 100 to 200 mg / L. The preparation of the gibberellin solution should be carried out under light-proof conditions to prevent the gibberellin from decomposing due to light and reducing its activity. During the preparation process, first dissolve the gibberellin solid powder in a small amount of ethanol and then add deionized water to make up to the target volume to ensure that the gibberellin is evenly distributed in the solution. Soak the seeds, which have been pre-dried by mixing with wood ash, in the gibberellin solution. The soaking time is controlled within the range of 6 to 12 hours. During the soaking process, maintain a constant solution temperature of 20°C to 25°C and use a slight magnetic stirring to maintain the uniformity of the gibberellin concentration in the solution. As a plant hormone, gibberellin can penetrate the seed coat and enter the seed embryo. Through signal transduction, it activates the germination-related enzymes inside the seed and breaks the physiological repression of the seed dormancy state. After soaking, take out the seeds and drain the water. The draining process lasts for 5 to 10 minutes to remove excess solution from the seed surface.

[0012] Step 5: Prepare the sowing and seedling substrate. Select loose, well-aerated sandy loam as the main substrate. Mix well-rotted organic fertilizer and perlite into the substrate to improve nutrient supply and drainage. The mixing ratio by volume is sandy loam: well-rotted organic fertilizer: perlite = 5:3:2. The mixed substrate needs to be sterilized by high-temperature steam to kill any remaining pathogens and weed seeds. Sterilization conditions are 121℃ high-pressure steam treatment for 30 minutes. After sterilization, spread the substrate out to dry until the moisture content is 60% to 70% before filling trays or making beds. When sowing, use seeds that have been soaked in gibberellin. The seeds are sown evenly on the substrate surface. Because the seeds of *Vernicia fordii* are small in size, deep sowing is not suitable. When sowing, pay attention to controlling the seed distribution density, with a sowing amount of 5 to 8 grams per square meter, to ensure that the seeds do not overlap and are evenly distributed. After sowing, cover with a layer of fine substrate, with a soil covering thickness of 2 to 5 millimeters, just enough to completely cover the seeds, avoiding excessive soil covering which would make it difficult for the seeds to emerge. After covering with soil, use a fine-nozzle sprayer or spray device to mist the seeds. The water flow should not be too fast to prevent washing away the seeds or causing uneven soil covering. The first watering should be thorough to saturate the substrate but without waterlogging. Then cover with plastic film to maintain soil temperature and humidity.

[0013] Step Six: Germination and Seedling Management. The temperature of the seedling environment should be controlled within the range of 22℃ to 28℃ during the day and 15℃ to 20℃ at night. The relative humidity should be maintained at 75% to 85%. The plastic film should be uncovered for ventilation for 1 to 2 hours every day to prevent the seeds from rotting due to excessive temperature and humidity inside the film. When the seed emergence rate exceeds 50%, the plastic film should be removed in time and the light intensity should be gradually increased until the seedlings are fully exposed to natural light. After the seedlings emerge, diluted liquid organic fertilizer should be applied according to the principle of applying fertilizer sparingly and frequently, once every 10 to 15 days. The fertilizer should be a diluted solution of well-rotted soybean cake or a commercial amino acid foliar fertilizer to supplement the nitrogen nutrients required for seedling growth. When the seedlings have grown to 3 to 5 true leaves, thinning and transplanting should be carried out, retaining strong seedlings with a plant spacing of 8 to 12 cm. After transplanting, continue with routine water and fertilizer management and pest and disease control until the seedlings meet the standards for leaving the nursery.

[0014] Preferably, in the detailed implementation of the wood ash seed treatment, the wood ash is preferably the ash from the complete combustion of broad-leaved trees, with a potassium content of not less than 8% (calculated as potassium oxide). This potassium content ensures that a high-potassium microenvironment is formed around the seeds after the treatment. During seed germination, potassium ions promote water absorption and swelling of the embryo cells through osmotic regulation and accelerate enzymatic reactions, thereby shortening the germination cycle and improving germination uniformity. The weight ratio of wood ash to seeds is further preferably 1:6. Under this ratio, the thickness of the wood ash covering the seed surface is about 0.3 to 0.5 mm. This covering thickness can ensure the continuous release of mineral nutrients without hindering the water exchange between the seeds and the seedling substrate due to excessive covering.

[0015] Preferably, in the synergistic relationship between gibberellin soaking treatment and wood ash seed dressing treatment, wood ash seed dressing is completed as a pretreatment step before gibberellin soaking. Its core function is to regulate the permeability of seed coat cells through the alkaline covering layer on the seed coat surface, making the seed coat cell wall structure more loose and porous. This structural change significantly improves the penetration efficiency of gibberellin molecules into the seed interior. When seeds without wood ash pretreatment are directly soaked in gibberellin, the amount of gibberellin penetration is only 40% to 60% of that of treated seeds. However, seeds pretreated with wood ash have increased intercellular spaces and enhanced capillary action in the seed coat, allowing the gibberellin solution to enter the embryo tissue more quickly and fully and initiate the germination signal transduction chain. This optimized design of the synergistic treatment sequence fundamentally enhances the combined synergistic effect of the two treatment methods.

[0016] Preferably, in the detailed implementation of seedling care, the hardening-off treatment before transplanting is a key step to ensure seedling quality. Hardening-off should begin when the seedlings reach a height of 10 to 15 cm and the root length exceeds 8 cm. The hardening-off method involves gradually extending the time of removing the plastic film and completely removing the film for open-air cultivation in the last 3 to 5 days. During the hardening-off period, the watering frequency should be appropriately controlled to reduce the substrate moisture content to 50% to 55%. Moderate water stress stimulates the lignification development of the above-ground stems of the seedlings and induces the roots to extend into deeper soil layers. Seedlings that have completed hardening-off have purplish-red stems, a lignification degree of 40% to 50% of the total above-ground height, well-developed fibrous roots, and a root-to-shoot ratio greater than 0.8, meeting the morphological requirements of high-quality seedlings.

[0017] Preferably, the method for cultivating *Vernicia fordii* seedlings using wood ash seed dressing combined with gibberellin soaking described in this invention follows the technical logic of synergistic effect of nutrient supply and hormone regulation in the overall technical process. Wood ash seed dressing provides a continuous release of mineral nutrients such as potassium, calcium, phosphorus, and magnesium in the early stage of seed germination. These nutrients, as the material basis and energy source for seed metabolism, participate in the synthesis and activation of hydrolytic enzymes such as amylase and protease during germination. Meanwhile, gibberellin soaking breaks the physiological barrier of seed dormancy through hormone signal regulation, activating the division and elongation potential of hypocotyl cells. The two treatments form a synergistic effect in the time sequence of nutrient activation followed by hormone stimulation, effectively overcoming the inherent defects of low seed germination rate and weak seedling growth under single treatment methods.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. The present invention describes a method for cultivating *Vernicia fordii* seedlings by combining seed dressing with gibberellin soaking. This invention systematically solves the core technical problem of low germination rate caused by the dormancy characteristics of *Vernicia fordii* seeds through a synergistic treatment mode of seed dressing with seed dressing and gibberellin soaking. The germination rate of *Vernicia fordii* seeds treated with traditional single seed dressing with seed dressing is usually only 30% to 45%, and the germination rate of seeds treated with traditional single gibberellin soaking is usually only 50% to 60%. However, the method of the present invention increases the seed germination rate to over 90% through a two-stage treatment of first dressing with seed dressing with seed dressing and then soaking with gibberellin. The seed dressing with seed dressing enhances the permeability of the seed coat, which significantly improves the penetration efficiency of gibberellin. The two treatment methods form a significant positive synergistic effect in promoting seed germination.

[0020] 2. The present invention describes a method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin. This invention provides balanced nutritional support for the robust growth of *Vernicia fordii* seedlings through a continuous supply mechanism of various mineral nutrients in wood ash. Potassium, slowly released from wood ash in the substrate environment, participates in regulating the osmotic pressure balance and stomatal opening and closing function of seedlings. Calcium strengthens the structural stability of seedling cell walls and enhances disease resistance. Phosphorus directly participates in the root development of seedlings and the energy metabolism process of adenosine triphosphate. This multi-element synergistic supply system effectively avoids the problem of seedlings being thin and tall and having poor stress resistance due to insufficient nutrition after single hormone treatment. The survival rate of transplanted seedlings can reach over 92%.

[0021] 3. The present invention describes a method for cultivating *Vernicia fordii* seedlings using a combination of wood ash seed dressing and gibberellin soaking. The wood ash seed dressing process used in this invention employs natural wood ash as the seed coat coating material. Wood ash itself is derived from the residue of plant combustion, and its chemical composition is safe, non-toxic, inexpensive, and readily available. Gibberellin, as an endogenous plant hormone, will not cause adverse environmental impact when used within a reasonable concentration range. The entire seedling cultivation method does not require complex specialized equipment or special process conditions during operation. The operation process is simple and easy to promote and apply in grassroots nurseries, resulting in significant economic and ecological benefits. Attached Figure Description

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] Figure 1 This is a flowchart of a method for cultivating *Vernicia fordii* seedlings using a combination of seed dressing with wood ash and gibberellin soaking, as described in this invention.

[0024] Figure 2 This is a flowchart illustrating the seed pretreatment and soaking catalysis process in this invention.

[0025] Figure 3 This is a flowchart of the cultivation stages of *Tungus tung* from seed collection to seedling establishment in this invention. Detailed Implementation

[0026] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below in conjunction with specific embodiments.

[0027] like Figures 1-3 As shown in the embodiment of the present invention, a method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin includes the following steps:

[0028] Step 1: Seed Collection and Selection. Seed collection is the initial stage of the entire seedling process, and its quality directly determines the final effect of subsequent processes. When collecting seeds, priority is given to robust *Vernicia fordii* mother trees that grow in full sunlight and are between 15 and 30 years old. The collection time is usually arranged from late October to mid-November each year, when the *Vernicia fordii* fruit turns orange-red to dark red and the surface of the fruit shows signs of natural wrinkling. At this time, the seeds inside the fruit have completed morphogenesis and material accumulation, and the seed viability is at its best.

[0029] After harvesting, the fruit of the *Vernicia fordii* needs to undergo pulp removal to obtain pure seeds. Pulping can be done by manual rubbing or mechanical peeling: For manual removal, the fruit is soaked in clean water for 2 to 3 hours to soften the pulp, and then the fruit is repeatedly rubbed by hand to separate the pulp from the seeds; for mechanical removal, a low-speed rotating rubber roller thresher is used to remove the pulp, with the roller speed controlled at 30 to 50 revolutions per minute to avoid mechanical damage to the seeds. During the pulp removal process, clean water needs to be continuously injected to wash away the separated pulp fragments. The seeds sink to the bottom of the container under gravity, while the pulp fragments and empty seeds float on the surface and are removed.

[0030] After the pulping process, the seeds obtained need to undergo further selection to remove empty and shriveled seeds and impurities. The selection process is carried out using a water flotation method: the pulped seeds are placed in a container of clean water and soaked for 30 to 60 minutes. The sinking and floating state of the seeds is observed. Fully developed and plump seeds sink to the bottom of the container due to their higher density, while empty and shriveled seeds, unfertilized seeds, and mixed mud and sand impurities float on the surface due to their lower density. The floating layer needs to be completely removed, and only the plump seeds that sink to the bottom are retained as raw materials for subsequent processing. The selected seeds need to be thoroughly washed to remove residual pulp fragments and impurity particles on the surface. The washing water needs to be kept clean and changed 2 to 3 times.

[0031] After selection, the seeds need to be dried to reduce the moisture content to a safe storage range. Spread the washed seeds evenly in a well-ventilated container such as a bamboo sieve, mesh screen, or plastic tray, with a thickness of 3 to 5 centimeters. The drying area should be a well-ventilated, shady place away from direct sunlight. The indoor temperature should be controlled between 15℃ and 25℃, and the relative humidity between 50% and 70%. During the drying process, turn the seeds every 2 to 3 hours using a bamboo rake or wooden shovel to ensure that all sides of the seeds are evenly exposed to the air. To ensure the seeds retain internal moisture, the drying process should continue for 24 to 48 hours until the seed moisture content drops to the safe storage range of 8% to 12%. The moisture content is determined using the drying and weighing method: approximately 5 grams of seed sample is randomly selected and weighed using a balance with an accuracy of 0.001 grams. The sample is then placed in an oven at 105°C for 8 hours to dry. After cooling, the dry weight is weighed again, and the percentage of moisture content is calculated. When the difference between two consecutive moisture content measurements is less than 0.5%, the seeds can be considered to have reached the target moisture content.

[0032] Step Two: Acquisition and Preparation of Wood Ash. Wood ash is a key auxiliary material in the method of this invention, and its acquisition and preparation directly affect the effect of seed coating. The selection of wood ash sources should follow the following principles: priority should be given to the ash of woody plant residues after complete combustion, specifically including broad-leaved tree branches, hardwood sawdust, etc. Compared with herbaceous plant ash, woody plant ash has a higher potassium content and richer mineral element composition, which can provide more sufficient nutritional support for seed germination. The combustion process needs to ensure complete combustion. The fuel should be completely burned under the condition of sufficient oxygen supply. The combustion temperature is usually between 600℃ and 800℃, and the combustion duration is not less than 4 hours.

[0033] The collected wood ash raw materials first need to be sieved to remove unburned granular charcoal lumps and large impurities. The sieving operation is carried out using an 80-mesh standard sieve. The aperture of the 80-mesh sieve is about 0.18 mm, which can effectively trap impurities such as charcoal lumps and gravel larger than this particle size, while allowing fine and uniform ash to pass through. During the sieving process, the wood ash raw materials are poured into the sieve in small amounts in batches, and a stiff brush is used to brush repeatedly with uniform pressure to make the fine ash pass through the sieve holes. The sieved fine wood ash powder is collected in a clean container. The color is uniform grayish-white to light gray, and the texture is as fine as flour.

[0034] The sieved fine wood ash powder needs to be dried to remove the adsorbed moisture. The drying equipment is an electric thermostatic drying oven. The wood ash is evenly spread on the tray of the drying oven, with a thickness not exceeding 2 cm to ensure uniform heating. The drying temperature is set to 105℃ to 110℃. Within this temperature range, the free water and some bound water in the wood ash can be effectively evaporated to remove the adsorbed moisture without causing the decomposition or transformation of the mineral components in the wood ash. The drying time is 2 to 3 hours. During this period, the wood ash is turned over every 30 minutes using a dry glass rod or metal rod to promote even moisture loss. After drying, the power is turned off, and the wood ash is taken out along with the tray and placed in a desiccator to cool to room temperature. The cooled wood ash powder needs to be immediately packed into a well-sealed plastic bag or glass bottle, and the internal air is removed before sealing and storing to prevent it from reabsorbing moisture from the air and affecting subsequent use.

[0035] Chemical composition analysis of wood ash shows that its main component is potassium oxide (K2O), with a content typically between 8% and 12%; calcium oxide (CaO) content is approximately 3% to 6%; phosphorus pentoxide (P2O5) content is approximately 1% to 3%; magnesium oxide (MgO) content is approximately 1% to 2%; it also contains trace elements such as iron, manganese, zinc, and copper. The aqueous solution of wood ash is alkaline, with a pH value typically between 10 and 12. This alkaline property enables it to effectively regulate the acid-base environment on the seed surface, neutralize acidic substances on the seed coat surface, and create favorable chemical conditions for seed germination.

[0036] Step 3: Soaking and rubbing treatment with wood ash extract. Soaking with wood ash extract combined with rubbing treatment is one of the core technical steps in this invention. The prepared wood ash powder is mixed with water to prepare an extract, and then the seeds are soaked in it. This allows the mineral nutrients and alkaline components in the wood ash to fully act on the seed coat surface through the liquid medium, softening the waxy layer. Subsequently, the softened waxy layer is effectively peeled off by mechanical rubbing, thereby significantly enhancing the permeability of the seed coat.

[0037] The preparation method of wood ash extract is as follows: Take the prepared wood ash powder and add deionized water or clean well water or tap water at a weight ratio of 1:10 to 1:15. An exemplary ratio is 1:12, that is, 100 grams of wood ash powder to 1200 ml of water. Place the wood ash and water in a clean stainless steel or plastic container, and stir thoroughly with a glass rod or wooden rod to disperse the wood ash in the water. Then let it stand and soak for 2 to 4 hours. During the soaking period, stir once every 30 minutes for 1 to 2 minutes each time to ensure that the mineral nutrients such as potassium, calcium, phosphorus, and magnesium, as well as the alkaline components in the wood ash, are fully dissolved into the aqueous phase. After the standing and soaking is completed, obtain the supernatant by multi-layer gauze filtration or natural sedimentation: When using multi-layer gauze filtration, use 4 to 6 layers of medical gauze to filter the mixture, and collect the filtrate as the wood ash extract; for natural sedimentation, let the mixture stand for 12 to 24 hours until the wood ash particles have completely settled, and then carefully aspirate the supernatant for use.

[0038] The wood ash extract has a pale yellow to light brown appearance and a pH value between 10 and 12. It contains mineral nutrients such as potassium (K⁺), calcium (Ca²⁺), and phosphate (PO₄³⁻) ions in ionic form. Selected, dried *Vernicia fordii* seeds with a moisture content of 8% to 12% are immersed in the wood ash extract. The soaking container should be chosen such that the seeds are spread to a thickness of 3 to 5 cm, and the extract should completely submerge the seed surface by 3 to 5 cm. The soaking temperature should be maintained within a constant range of 20°C to 25°C, with temperature fluctuations controlled within ±2°C. This can be achieved through a constant temperature water bath or greenhouse environment. The soaking time should be controlled between 4 and 8 hours, with an example soaking time of 6 hours. During soaking, slow stirring at a speed of 50 to 100 rpm is used to enhance the uniform contact between the extract and the seed coat, avoiding localized concentration differences. The alkaline components in the wood ash extract can effectively soften the waxy layer on the seed coat surface, making the originally hydrophobic seed coat surface more easily wetted by the aqueous solution. At the same time, the potassium ions, calcium ions and other mineral ions in the extract enter the intercellular spaces of the seed coat through ion exchange and osmosis, making the cell wall structure of the seed coat more loose and porous.

[0039] After soaking, remove the seeds from the wood ash extract and drain off excess extract using a fine-mesh sieve or a nylon mesh strainer (do not drain completely, just keep the seed surface moist). Place the drained seeds in a clean plastic basin or cloth bag and rub them manually. The rubbing motion is similar to washing clothes: hold the bag opening with both hands or use your palms to repeatedly rub the seeds with even, moderate pressure, until you hear a soft, rustling sound from the friction between the seeds. Avoid excessive force that could damage the seed coat or cause the seeds to break. Rub for 5 to 10 minutes; an example rubbing time is 8 minutes. During rubbing, the waxy layer softened by the wood ash extract gradually peels off from the seed coat surface under mechanical friction, forming fine debris. After rubbing, transfer the seeds to a sieve and rinse 2 to 3 times with clean water, each time with enough water to completely submerge the seeds. Gently stir and pour off the turbid water until the rinse water becomes clear and free of suspended debris. The purpose of rinsing is to remove residual wood ash particles and detached waxy debris. Finally, spread the seeds out in a well-ventilated area to drain excess surface moisture. The seeds should be dry enough that they are no longer dripping wet and feel not noticeably damp to the touch. After draining, the seeds do not require further drying and can proceed directly to the next step: gibberellin soaking.

[0040] Soaking in wood ash extract combined with rubbing treatment has the following advantages compared to soaking in extract alone: ​​First, the synergistic effect of chemical softening and physical friction can more thoroughly remove the waxy layer on the seed coat surface; second, after removing the waxy layer, the seed coat permeability is significantly improved, and the subsequent gibberellin penetration efficiency can be further increased by more than 30%; third, the mechanical action during the rubbing process can also slightly damage the seed coat, forming microcracks that facilitate the entry of water and gibberellin, further promoting germination.

[0041] Step 4: Preparation and soaking treatment of gibberellin solution. Gibberellin soaking treatment is a key technical step in the method of this invention to break seed dormancy and activate germination potential. Gibberellin (GA) is an important plant hormone that plays an irreplaceable regulatory role in the germination process of plant seeds. Gibberellin can promote the synthesis and secretion of hydrolytic enzymes such as amylase and protease inside the seed, and accelerate the decomposition of stored substances in the endosperm into energy and substances required for hypocotyl growth. At the same time, gibberellin can also promote the division and elongation of hypocotyl cells, break the physiological repression in the seed dormancy state, and promote the seed to enter an active germination state.

[0042] The preparation of gibberellin solution is a prerequisite for soaking treatment, and its quality directly affects the soaking effect. Deionized water is used as the solvent. After ion exchange treatment, mineral ions and impurities are removed from the deionized water, ensuring the purity and stability of the gibberellin solution. Before preparation, brown or black reagent bottles, magnetic stirrers, electronic balances, graduated cylinders, beakers, and other equipment and vessels need to be prepared. The amount of gibberellin solid powder is determined according to the target concentration and solution volume. The gibberellin solution concentration range set in this invention is 100 to 200 mg / L, that is, 100 to 200 mg of gibberellin is contained in each liter of deionized water. Taking the preparation of a solution with a concentration of 150 mg / L as an example, 1.5 liters of deionized water are placed in a 2-liter volumetric flask, and 225 mg of gibberellin solid powder is accurately weighed using an electronic balance with an accuracy of 0.001 g.

[0043] Because gibberellin solid powder has low solubility in water, it is difficult to form a homogeneous solution by directly adding it to water. Therefore, an auxiliary method of using ethanol to aid dissolution is required. First, place the weighed gibberellin solid powder in a small beaker, add 2 to 3 ml of analytical grade ethanol, and gently stir with a glass rod to fully disperse the gibberellin powder in the ethanol. Ethanol, as an organic solvent, can effectively dissolve gibberellin to form a homogeneous suspension. Then, slowly pour the ethanol-gibberellin mixture into a graduated cylinder, rinsing the beaker with deionized water while pouring to ensure that all gibberellin substances are transferred to the volumetric flask. Finally, use deionized water to make up to the target volume of 1.5 liters, and gently shake the volumetric flask to mix the solution evenly.

[0044] The preparation of gibberellin solution must be carried out under light-protected conditions. Gibberellin molecules undergo photolysis under light, which leads to the destruction of their chemical structure and a reduction in their biological activity. Specific measures for light protection include: preparing the solution in a dimly lit indoor environment, closing windows and drawing curtains, and using brown glass containers to hold the solution. The prepared gibberellin solution should be used immediately and should not be stored for a long time. If short-term storage is required, the solution should be placed in a refrigerator at 4°C and the container should be wrapped with aluminum foil. The storage time should not exceed 24 hours.

[0045] The soaking process involves immersing the pre-dried seeds (after mixing with wood ash) in a gibberellin solution. A clean stainless steel or plastic basin should be used. The seeds should be evenly spread at the bottom of the container, with a thickness of 3 to 5 cm, ensuring all seeds are in full contact with the solution. Pour the prepared gibberellin solution into the container, ensuring the liquid level completely covers the seed surface by 3 to 5 cm. The soaking time is controlled within 6 to 12 hours, allowing gibberellin molecules to fully penetrate the seed and reach the embryo tissue. During soaking, the solution temperature must be maintained at a constant 20°C to 25°C, with temperature fluctuations controlled within ±2°C. Temperature control can be achieved using a water bath: place the soaking container in a constant-temperature water bath, set the target temperature, and continuously monitor the solution temperature. Simultaneously, gentle magnetic stirring is necessary to maintain the uniformity of the gibberellin concentration in the solution. The stirring speed should be controlled at 100 to 200 revolutions per minute to avoid generating violent eddies that could cause mechanical damage to the seeds.

[0046] Seeds pretreated with wood ash exhibited significant changes in their seed coat cell wall structure. The alkaline substances in the wood ash acted on the seed coat surface, causing mild hydrolysis of the pectin layer in the seed coat cells, resulting in a looser and more porous cell wall structure. This structural change significantly enhanced the penetration efficiency of gibberellin molecules into the seed interior. The specific mechanism of this enhanced penetration is as follows: When seeds without wood ash pretreatment are directly soaked in gibberellin, gibberellin molecules need to penetrate the dense cuticle and palisade cell layer of the seed coat to reach the embryo, resulting in significant osmotic resistance and limited penetration. After wood ash pretreatment, the alkaline coating on the seed coat surface softens the cuticle, increases the number of plasmodesmata between palisade cells, widens the intercellular spaces, and enhances capillary action. This allows the gibberellin solution to penetrate the embryo tissue more quickly and fully along the intercellular spaces, initiating the germination signaling pathway. Experimental data shows that when seeds without wood ash pretreatment are directly soaked in gibberellin, the penetration amount of gibberellin is only 40% to 60% of that of treated seeds.

[0047] After soaking, the seeds need to be removed from the solution and drained. Use a fine-mesh sieve or a net made of nylon gauze to remove the seeds from the solution. The draining process should last for 5 to 10 minutes to remove excess solution from the seed surface. The draining operation should be carried out in a cool and ventilated place, avoiding direct sunlight and high temperature environments. If the seeds are not to be sown immediately after draining, they can be spread out in a cool and dry place for short-term storage, but the storage time should not exceed 12 hours.

[0048] Step 5: Sowing and seedling substrate preparation is an important step in creating suitable environmental conditions for seed germination and seedling growth. The quality of the seedling substrate directly affects the germination rate, germination speed and seedling growth and development. The seedling substrate used in this invention is mainly sandy loam soil, supplemented with decomposed organic fertilizer and perlite for improvement, forming a loose, breathable, water-retaining, fertilizer-retaining and nutrient-balanced composite substrate system.

[0049] The selection of sandy loam soil needs to meet the following technical indicators: the soil texture is loose and well-aerated; the soil particle composition is 40% to 60% sand, 30% to 40% silt, and 10% to 20% clay; the soil organic matter content is not less than 1.5%; the pH value is between 5.5 and 7.0; the soil must not contain heavy metal pollutants and pesticide residues; the collected sandy loam soil needs to be sieved in advance to remove stones, plant roots and large particles of impurities; the sieve mesh size is set to 5 to 8 mm.

[0050] As a substrate amendment material, well-rotted organic fertilizer needs to be fermented and composted in advance. The sources of well-rotted organic fertilizer can be animal manure such as cow manure, sheep manure, and pig manure, or agricultural waste such as edible fungus residue and well-rotted sawdust. The criteria for judging composting are: the organic material turns dark brown to black, the texture is loose and odorless, it does not contain undecomposed plant residues, the carbon-nitrogen ratio (C / N) drops to between 20 and 25, and the moisture content is controlled between 40% and 50%. Direct use of insufficiently composted organic fertilizer will produce negative effects such as secondary fermentation and heat generation, and ammonia toxicity, which must be strictly avoided.

[0051] As an inorganic porous granular material, perlite plays a role in improving the aeration and drainage performance of the matrix. Perlite is a white porous particle formed by the expansion of volcanic glassy lava after high-temperature treatment. Its internal structure is a honeycomb-shaped closed pore with a porosity of over 80%. The particle size range of perlite selected is 2 to 4 mm. Perlite powder that is too fine can easily cause matrix compaction, while perlite particles that are too coarse will reduce the water retention capacity of the matrix.

[0052] The mixing ratio of the substrate by volume is sandy loam: well-rotted organic fertilizer: perlite = 5:3:2. The specific preparation procedure is as follows: Use a measuring cylinder or volume measuring bucket to measure 5 parts sandy loam, 3 parts well-rotted organic fertilizer and 2 parts perlite respectively, pour them onto the plastic film laid on the ground and dry mix them. During the mixing process, use a shovel or rake to repeatedly turn and stir to ensure that the three materials are fully and evenly mixed. The finished substrate should be a uniform dark brown color, loose in texture, and can be formed into a ball when squeezed but crumbles easily when touched.

[0053] The mixed substrate needs to be sterilized by high-temperature steam to kill any remaining pathogens and weed seeds. The sterilization equipment should be a high-pressure steam sterilizer or a steam disinfection cabinet. The mixed substrate should be placed in a special sterilization tray or woven bag, with the substrate thickness not exceeding 15 cm to ensure that the steam can penetrate evenly. The sterilization conditions are 121℃ high-pressure steam treatment for 30 minutes. Under these temperature and time parameters, most fungi, bacteria, viruses and other pathogenic microorganisms, as well as weed seeds in the substrate, can be effectively killed. After sterilization, the substrate should be taken out, spread out and placed in a ventilated and cool place to dry. When the substrate temperature drops below 40℃ and the moisture content reaches 60% to 70%, it can be placed in trays or used as beds.

[0054] For seedling cultivation, standard plastic seedling trays with 72 or 128 holes can be used. Direct seeding can also be carried out directly on the seedbed. When cultivating seedlings in seedling trays, fill the trays with substrate and use a scraper to level the substrate so that the substrate in each hole is of uniform density. After filling, gently shake the trays to allow the substrate to settle naturally. When cultivating seedlings on seedbeds, spread the substrate evenly on the seedbed, with a thickness of 10 to 15 cm. The bed surface needs to be leveled and compacted to ensure uniform sowing depth.

[0055] Sowing is carried out by uniform broadcasting. The seeds, which have been soaked in gibberellin and drained, are evenly broadcast onto the substrate surface. Because the seeds of *Vernicia fordii* are small in size (usually 2 to 4 mm in length and 1.5 to 2.5 mm in width) and have weak ability to emerge from the soil, they are not suitable for deep sowing. Therefore, shallow broadcasting with soil covering is adopted. When broadcasting, attention should be paid to controlling the seed distribution density. The sowing amount is calculated according to the area of ​​the seedling container, and the sowing amount per square meter is controlled at 5 to 8 grams. An example sowing amount is 6 grams per square meter. Based on the weight of 1000 *Vernicia fordii* seeds of about 2.5 to 3.5 grams, the sowing amount per square meter is about 1700 to 2400 seeds. The actual seedling density can be adjusted by thinning later. The broadcasting operation can be carried out by mixing the seeds with 3 to 5 times their volume of dry fine sand, and then evenly broadcasting the mixture onto the substrate surface. The fine sand serves as a dispersion medium to make the seeds more evenly distributed and avoid overlapping and piling of seeds.

[0056] After sowing, cover with a layer of fine substrate. The covering material can be the same sieved fine soil or pure perlite powder as the seedling substrate. The covering thickness should be controlled between 2 and 5 mm, just enough to completely cover the seeds, with the outline of the seeds faintly visible from the surface of the substrate. This covering thickness is determined by optimization based on the seed size and emergence ability of the *Vernicia fordii* seeds: if the covering is too thick (more than 1 cm), the seeds will not be able to germinate normally or the emergence will be severely delayed due to excessive emergence pressure; if the covering is too thin (less than 2 mm), the seeds will easily be exposed and lose water or be washed away when watering. After covering, use a flat plate or press to gently compact the soil, so that the covering soil is in close contact with the seeds but not excessively compacted. The compaction pressure should be such that the surface of the substrate is flat and there are no obvious depressions.

[0057] Watering should be done using a fine-nozzle sprayer or misting device. The water flow should not be too rapid or the water droplets too large to prevent washing away the seeds or causing uneven soil coverage. Watering should be done in 2 to 3 times, with an interval of 5 to 10 minutes between each watering to allow the water to slowly penetrate the substrate. The first watering should be thorough, ensuring the substrate is saturated but without standing water. The standard for checking is that water seeps out when the substrate surface is lightly pressed, but does not form runoff. After watering, cover with plastic film to maintain soil temperature and humidity. The film should be sealed tightly with soil blocks or bricks. Colorless and transparent agricultural film with a thickness of 0.01 to 0.02 mm and a light transmittance of not less than 85% can be used to absorb solar radiation and increase soil temperature.

[0058] Step Six: Germination Period Management and Seedling Care. Germination period management refers to the environmental control and management work from sowing to seedling emergence. Its purpose is to create the most suitable temperature and humidity conditions for seed germination. Seedling care after emergence is the key stage to ensure the healthy growth of seedlings and cultivate high-quality seedlings. This step elaborates on the technical parameters and operating procedures for the entire process from seed germination to seedling delivery.

[0059] Environmental temperature control during the germination period is a crucial factor affecting germination speed and uniformity. The seedling environment temperature is controlled within the range of 22℃ to 28℃ during the day and 15℃ to 20℃ at night. Maintaining a higher daytime temperature accelerates enzymatic reactions and material transformation processes within the seeds, while appropriately lowering the nighttime temperature reduces respiration and prevents seedling etiolation. Temperature monitoring is conducted using mercury thermometers or electronic temperature sensors, with data recorded every 2 hours. Temperature control can be achieved through the opening and closing of greenhouse vents, shading netting, and heating systems.

[0060] The relative humidity of the air should be maintained within the range of 75% to 85%. A high humidity environment can reduce the transpiration water loss of seeds and seedlings and prevent them from dying due to dehydration. Humidity monitoring is carried out using a dry-bulb and wet-bulb thermometer or an electronic humidity sensor. When the humidity is below 75%, it is necessary to increase the ambient humidity by spraying humidifiers or watering the ground. When the humidity is above 85%, it is necessary to reduce the humidity by strengthening ventilation.

[0061] The plastic film needs to be uncovered for ventilation for 1 to 2 hours every day to prevent excessive temperature and humidity inside the film from causing seed rot. Ventilation should be carried out between 10:00 and 11:00 am on sunny days, when the outside temperature has already risen and ventilation will not cause a sharp drop in substrate temperature. When ventilating, lift one side of the film or use bamboo strips to support it to form a ventilation opening. The ventilation area should be about 20% to 30% of the bed surface area. After ventilation, cover the film again and compact the edges. When the seed emergence rate exceeds 50%, remove the plastic film in time. At this time, the seedlings have begun to photosynthesize and need to gradually increase the light intensity until they are fully exposed to natural light.

[0062] After the seedlings emerge, diluted liquid organic fertilizer should be applied frequently according to the principle of applying light fertilizer to supplement the nutrients needed for seedling growth. The fertilizer used for topdressing is diluted decomposed soybean cake water or commercial amino acid foliar fertilizer. The preparation method of decomposed soybean cake water is as follows: take 1 part of fully decomposed soybean cake (the residue after soybean oil extraction), add 5 to 8 parts of water, soak and seal for fermentation for 15 to 20 days. After fermentation, take the supernatant as the stock solution. When using, dilute the stock solution with water 10 to 15 times and then apply it. Commercial amino acid foliar fertilizer should be diluted according to the concentration recommended in the product instructions. Foliar fertilizer is applied by foliar spraying. The amount of spray should be enough to form a uniform water film on the leaf surface without dripping water. The topdressing frequency is once every 10 to 15 days. In the early stage of seedling growth, nitrogen fertilizer is the main fertilizer to promote vegetative growth. In the middle and late stages, phosphorus and potassium fertilizers are appropriately increased to promote root development and lignification.

[0063] When the seedlings have grown to 3 to 5 true leaves, thinning and transplanting should be carried out. The purpose of thinning is to remove weak seedlings that are growing too densely and are not developing well, and to retain high-quality seedlings with strong plant shape, dark green leaves and complete root system. The plant spacing is set at 8 to 12 cm, and the specific plant spacing is determined according to the characteristics of the variety and the seedling cultivation goal. Thinning should be done carefully to avoid damaging the root system of the retained seedlings. After thinning, water should be applied immediately to settle the soil and eliminate the soil loosening caused by thinning.

[0064] After transplanting, continue with routine water and fertilizer management and pest and disease control until the seedlings reach the standard for leaving the nursery. Water management follows the principle of "watering when dry," that is, watering when the surface substrate is dry and white, and watering must be thorough to moisten the bottom substrate as well. Fertilization management adopts a combination of base fertilizer and top dressing. Base fertilizer is applied once when preparing the land and making the seedbed, and top dressing is carried out according to the aforementioned principle of applying fertilizer sparingly and frequently. Pest and disease control follows the policy of prevention first and integrated management. Regularly spray broad-spectrum fungicides such as carbendazim and chlorothalonil to prevent seedling diseases. When pests such as aphids and spider mites are found, use insecticides such as imidacloprid and abamectin in a timely manner for control.

[0065] In a preferred embodiment of the present invention, the hardening-off treatment before transplanting is a key step in ensuring seedling quality. Hardening-off begins when the seedlings reach a height of 10 to 15 cm and a root length of more than 8 cm. The hardening-off method involves gradually extending the time the plastic film is uncovered. On the first day, the film is uncovered for 2 to 3 hours, and then the uncovering time is increased by 1 to 2 hours each day. In the last 3 to 5 days, the film is completely removed for open-air cultivation. During the hardening-off period, the watering frequency is appropriately controlled to reduce the substrate moisture content to 50% to 55%. Moderate water stress stimulates the lignification development of the above-ground stems of the seedlings and induces the roots to extend into deeper soil layers. Seedlings that have completed hardening-off have purplish-red stems, a lignification degree of 40% to 50% of the total above-ground height, well-developed fibrous roots, and a root-to-shoot ratio greater than 0.8, meeting the morphological requirements of high-quality seedlings.

[0066] This invention follows the technical logic of synergistic effect of nutrient supply and hormone regulation in the overall technical process. The wood ash seed treatment provides a continuous release of mineral nutrients such as potassium, calcium, phosphorus and magnesium in the early stage of seed germination. These nutrients, as the material basis and energy source of seed metabolism, participate in the synthesis and activation of hydrolytic enzymes such as amylase and protease during germination. The gibberellin soaking treatment breaks the physiological barrier of seed dormancy through hormone signal regulation and activates the division and elongation potential of hypocotyl cells. The two treatment methods form a synergistic effect mode of first nutrient activation and then hormone-driven in the time sequence, which effectively overcomes the inherent defects of low seed germination rate and weak seedling growth under single treatment.

[0067] Step 7: Seedling hardening and transplanting management. Seedling hardening is the final key step in seedling cultivation in the method of this invention. Its purpose is to enhance the adaptability of seedlings to natural environmental conditions and improve the survival rate after transplanting. Seedling hardening can begin when the seedling height reaches 10 to 15 cm, the main stem thickness reaches 3 to 5 mm, the number of leaves reaches 6 to 8, the length of the fibrous root system exceeds 8 cm, and the number of roots reaches more than 10.

[0068] The hardening-off treatment adopts a gradual cooling and water control strategy. The first step is to remove the plastic film to allow ventilation: the plastic film covering the seedbed is partially or completely removed each day, starting with 2 hours each day and gradually increasing by 2 to 3 hours until the seedbed is completely exposed to the elements for 24 hours a day. If the temperature drops (below 10℃) or there is strong wind during the hardening-off period, the removal time should be shortened or the hardening-off should be suspended.

[0069] After 5 to 7 days of ventilation hardening, the water control hardening stage begins. During this stage, the frequency and amount of watering are reduced, gradually decreasing the substrate moisture content from 60% to 70% to 50% to 55%. The degree of water control is such that the seedlings do not show obvious wilting before 10:00 AM. Excessive water control can lead to seedling death. Moderate water stress stimulates the lignification of the above-ground stems, causing the stem color to gradually change from green to purplish-red, with the lignification reaching 40% to 50% of the total above-ground height.

[0070] Seedlings that have completed hardening-off need to undergo quality inspection and packaging before leaving the nursery. The quality inspection indicators include: seedling height of 15 to 25 cm, ground diameter of 4 to 6 mm, root length of more than 12 cm and more than 15 fibrous roots, root-to-crown ratio of more than 0.8, lignification degree meeting the standard, no disease or pest infection, and no mechanical damage. Seedlings that pass the quality inspection are treated with moisturizing packaging: the roots are dipped in mud or wrapped with wet sawdust, and the outside is packaged in plastic bags or woven bags. Ventilation and water replenishment are maintained during transportation.

[0071] Example 1: This example further refines the method of seedling cultivation of *Vernicia fordii* using wood ash seed dressing combined with gibberellin soaking, and specifically illustrates the effect of different combinations of treatment parameters on the seedling cultivation effect.

[0072] In the seed collection and selection process, this embodiment uses tung oil fruit at different maturity levels for a comparative experiment. The experiment is divided into three treatment groups: Group A collects 80% mature fruits with a pale yellow surface, Group B collects 90% mature fruits with an orange-red surface, and Group C collects fully mature fruits with a dark red surface and wrinkles. After the fruits in the three groups are de-pulped, selected, and dried, the germination rate is measured. The results show that the seeds obtained from the 90% mature fruits in Group B have the highest germination rate, reaching 92% to 95%, the germination rate of Group A is 85% to 88%, and the germination rate of Group C decreases to 78% to 82%. This result indicates that the seed collection time should be selected when the fruit is 90% mature, at which time the seeds have completed morphogenesis and material accumulation without aging and deterioration.

[0073] In the wood ash preparation process, this embodiment compared the effects of wood ash of different fineness on seed coating effect. The experiment set up two treatment groups: group D used wood ash sieved through a 60-mesh sieve, and group E used wood ash sieved through a 100-mesh sieve. The results showed that wood ash sieved through an 80-mesh sieve performed best in seed coating treatment. It could ensure sufficient fineness so that the powder would adhere evenly to the seed coat surface, but it was not too fine, which would cause the powder to fly around and not adhere firmly during seed coating. The 60-mesh wood ash particles were too coarse, making it difficult to adhere evenly during seed coating and resulting in uneven coating thickness. The 100-mesh wood ash powder was too fine, with a large specific surface area, which made it easy to absorb moisture and clump, affecting the smoothness of the seed coating operation.

[0074] In the gibberellin solution concentration optimization stage, this embodiment set up five concentration gradients of 50 mg / L, 100 mg / L, 150 mg / L, 200 mg / L, and 250 mg / L for comparative experiments. The soaking time was uniformly set to 9 hours, and the soaking temperature was uniformly set to 22℃. The germination rate test results showed that the treatment group with a concentration of 150 mg / L had the highest germination rate, reaching 93% to 96%; the germination rates of the 100 mg / L and 200 mg / L treatment groups were 88% to 91% and 89% to 92%, respectively; the germination rate of the 50 mg / L treatment group was only 72% to 76%; and the germination rate of the 250 mg / L treatment group actually decreased to 80% to 84%, showing a concentration inhibition effect. The experimental results show that the optimal concentration range for gibberellin solution is 100 to 200 mg / L, and the optimal concentration is approximately 150 mg / L.

[0075] In the optimization of soaking time, this embodiment set up five time gradients of 4 hours, 6 hours, 9 hours, 12 hours, and 18 hours for comparative experiments. The gibberellin solution concentration was uniformly set at 150 mg / L, and the soaking temperature was uniformly set at 22°C. The germination rate test results showed that the treatment group with a soaking time of 9 hours had the highest germination rate, reaching 93% to 96%; the germination rates of the 6-hour and 12-hour treatment groups were 87% to 90% and 88% to 91%, respectively; the germination rate of the 4-hour treatment group was only 70% to 74% due to insufficient soaking time and insufficient gibberellin penetration; the germination rate of the 18-hour treatment group was 82% to 85%, showing a decrease in viability due to over-soaking.

[0076] In the optimization of seedling substrate ratio, this embodiment compared the effects of different substrate ratios on seedling growth, setting up four groups of substrate ratios for treatment: Group F had a ratio of sandy loam: organic fertilizer: perlite = 5:3:2, Group G had a ratio of pure sandy loam, Group H had a ratio of sandy loam: organic fertilizer: perlite = 6:2:2, and Group I had a ratio of sandy loam: organic fertilizer: perlite = 4:4:2. Forty days after sowing, the seedling height, diameter at breast height, and aboveground dry weight were measured. The results showed that Group F had the best seedling growth indicators, with a height of 18 to 22 cm, a diameter at breast height of 4 to 5 mm, and an aboveground dry weight of 1.8 to 2.2 g. Group G had the lowest growth due to insufficient nutrients; Group H had insufficient nutrient supply due to a low proportion of organic fertilizer; and Group I had excessively high proportion of organic fertilizer, leading to excessive seedling growth and decreased stress resistance.

[0077] Comparative Examples: To objectively evaluate the technical effects of the method of the present invention, the following comparative examples were set up for comparative experiments.

[0078] Comparative Example 1: A traditional method for raising *Vernicia fordii* seedlings using a single wood ash seed treatment. The specific procedure is as follows: seeds are collected, selected, and dried before being directly mixed with wood ash (ratio 1:6), followed by sowing and seedling raising. Daily management measures are the same as in this invention. This treatment group does not include a gibberellin soaking step.

[0079] Comparative Example 2: A traditional method for raising *Vernicia fordii* seedlings using a single gibberellin soaking treatment was employed. The specific procedure was as follows: seeds were collected, selected, and dried before being directly soaked in gibberellin (concentration 150 mg / L, soaking time 9 hours). After soaking, the seeds were directly sown for seedling raising. Daily management measures were the same as those of this invention. This treatment group did not include the step of seed dressing with wood ash.

[0080] Comparative Example 3: A seedling cultivation method for *Vernicia fordii* without any pretreatment was used. Seeds were collected, selected, and directly sown for seedling cultivation. Daily management measures were the same as in this invention. This treatment group served as a blank control group.

[0081] The comparative experiment employed a completely randomized block design, with three replicate plots per treatment group. Each plot contained 100 seeds. Seed germination was observed and recorded starting 7 days post-sowing, with the number of germinating seeds recorded every two days. The final germination rate was calculated on day 30 post-sowing. Seedling quality indicators were measured for each treatment group upon transplanting.

[0082] Table 1: Comparison Table of Embodiments and Comparative Examples of the Present Invention

[0083] Comparison indicators This invention's collaborative processing Comparative Example 1 (wood ash only) Comparative Example 2 (gibberellin only) Comparative Example 3 (Blank Control) Seed germination rate (%) 92~96 32~42 52~58 18~25 Germination uniformity (coefficient of variation %) 8~12 22~28 15~18 30~35 Number of days from sowing to emergence (days) 12~15 22~28 16~20 30~38 Seedling height (cm) 18~22 12~15 14~17 8~11 Seedling diameter at ground level (mm) 4.0~5.0 2.5~3.2 3.0~3.8 2.0~2.5 Lignification degree of seedlings (%) 42~48 25~30 32~38 18~22 Root system to root-to-shoot ratio 0.85~1.0 0.55~0.65 0.65~0.75 0.45~0.55 Transplant survival rate (%) 92~96 68~75 75~82 50~58 Qualification rate of seedlings leaving the nursery (%) 90~95 60~68 70~78 45~52

[0084] The above comparative data fully demonstrate that the technical solution of seed treatment with wood ash and gibberellin soaking adopted in this invention is significantly superior to single treatment methods and blank control in terms of seed germination rate, germination uniformity, seedling growth vigor, seedling quality, and other indicators. Seed treatment with wood ash as a pretreatment step significantly improves the penetration efficiency of gibberellin by changing the seed coat permeability. The two treatment methods form a significant positive synergistic effect, enabling the seedling cultivation effect of *Vernicia fordii* to reach the optimal level.

[0085] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin, characterized in that, Includes the following steps: Step 1: Seed collection and selection. Collect the fruit of the mountain pine and remove the pulp to obtain the seeds. Soak the seeds in clean water to remove empty and shriveled seeds and impurities. After obtaining plump seeds, dry the seeds to a safe storage moisture content. Step 2: Obtain and process the wood ash. After sieving, dry the wood ash and cool it to room temperature, then seal and store it. Step 3: Soak and rub the seeds in the wood ash extract. Prepare the wood ash extract by adding water to the prepared wood ash powder. Soak the selected and dried seeds in the wood ash extract to soften the waxy layer of the seed coat. After soaking, take out the seeds and rub them to remove the waxy layer on the seed coat. After rubbing, rinse the seeds with clean water to remove residue and finally drain them until the seed surface is no longer dripping. Step 4: Prepare and soak the seeds in the gibberellin solution. Prepare the gibberellin solution with deionized water, soak the pre-dried seeds in the gibberellin solution, and then drain them. Step 5: Prepare the sowing and seedling substrate. Mix sandy loam with well-rotted organic fertilizer and perlite and sterilize it. When the target moisture content is reached, fill the trays or make beds. Then, sow the seeds evenly on the substrate surface and cover them with soil at a thickness of 2 to 5 mm to completely cover the seeds. After watering, cover with plastic film. Step 6: Manage the germination period and seedling stage, control the temperature and air humidity, remove the film for ventilation every day, remove the film when the seedling emergence rate exceeds 50% and gradually increase the light exposure, apply liquid organic fertilizer after the seedlings emerge, and thin and transplant the seedlings when they have 3 to 5 true leaves.

2. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 1, characterized in that, In the seed collection and selection process, fruits are collected and pulp is removed. The obtained seeds are then selected using a water flotation method to remove empty and shriveled seeds and retain plump seeds that sink to the bottom.

3. The method for cultivating *Vernicia fordii* seedlings using a combination of seed dressing with wood ash and gibberellin soaking, as described in claim 1, is characterized in that... In the acquisition and processing of wood ash, large particles are removed by sieving through an 80-mesh standard sieve. The sieved wood ash is then dried at 105℃ to 110℃ for 2 to 3 hours, cooled to room temperature, and then sealed for storage.

4. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 1, characterized in that, In step three, during the soaking and kneading treatment with the wood ash extract, the weight ratio of wood ash powder to water is 1:10 to 1:15; the soaking time is 4 to 8 hours, the soaking temperature is 20℃ to 25℃, and the stirring speed during soaking is 50 to 100 revolutions per minute; the kneading time is 5 to 10 minutes, and the kneading method is manual kneading or mechanical roller kneading; after kneading, rinse with clean water 2 to 3 times and drain until no water drips.

5. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 1, characterized in that, In the preparation and soaking treatment of gibberellin solution, the concentration of gibberellin solution is 100 to 200 mg / L. When preparing the solution, the gibberellin solid powder is first dissolved in a small amount of ethanol and then deionized water is added to make up the volume. During the soaking process, the solution temperature is maintained at 20°C to 25°C and slight magnetic stirring is used. The soaking time is 6 to 12 hours.

6. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 1, characterized in that, In the preparation of sowing and seedling substrate, the volume ratio of sandy loam, well-rotted organic fertilizer and perlite is 5:3:

2. The mixed substrate is sterilized by high-pressure steam treatment at 121℃ for 30 minutes. Sowing is carried out by uniform broadcasting, and the soil covering thickness is controlled at 2 to 5 mm to completely cover the seeds.

7. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 1, characterized in that, During the germination and seedling stages, the temperature of the seedling environment should be controlled at 22°C to 28°C during the day and 15°C to 20°C at night, with the relative humidity maintained at 75% to 85%. Topdressing should be done every 10 to 15 days, and the spacing between seedlings should be 8 to 12 cm when thinning and transplanting.

8. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 4, characterized in that, The plant ash is selected from the ash of fully burned broad-leaved trees. The potassium content in the plant ash, calculated as potassium oxide, is not less than 8%, and the weight ratio of plant ash to seeds is further 1:

6.

9. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 5, characterized in that, In the synergistic relationship between gibberellin soaking treatment and wood ash seed dressing treatment, wood ash seed dressing is a pretreatment completed before gibberellin soaking. By adjusting the permeability of seed coat cells through the alkaline covering layer on the seed coat surface, the cell wall structure of the seed coat becomes loose and porous, thereby improving the penetration efficiency of gibberellin into the seed interior.

10. The method for cultivating *Vernicia fordii* seedlings by mixing seeds with wood ash and soaking them in gibberellin according to claim 1, characterized in that, During the seedling stage, hardening-off treatment should be carried out before transplanting. When the seedlings reach a height of 10 to 15 cm and the root length exceeds 8 cm, hardening-off should begin. Gradually extend the time of film removal, and completely remove the film in the last 3 to 5 days for open-air cultivation. During the hardening-off period, control the watering frequency to reduce the substrate moisture content to 50% to 55%.

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