Method for increasing the lignin content in the roots of lauraceae fruit trees

Abstract

This invention discloses a method for increasing the lignin content in the roots of Lauraceae fruit trees, belonging to the field of plant physiological regulation technology. To increase the lignin content in the roots of Lauraceae fruit trees such as avocado trees, this invention employs the following techniques: application of a lignin-synthetic nutrient-enhancing solution; directional pulsed electric field treatment to enhance the permeability of the fruit tree's epidermal cell membranes; activation of key enzymes in phenylpropanoid metabolism by irradiation with specific wavelengths of ultraviolet light; and synergistic application of mechanical stress technology to stimulate and induce vascular tissue differentiation. By treating the roots of Lauraceae fruit trees, not only can the lignin content in the root system be increased by more than 30%, but the root system's stress resistance and mechanical strength can also be improved by more than 45%, while maintaining normal physiological metabolism of the plant. This provides a new solution for lodging-resistant cultivation and root rot prevention in Lauraceae fruit trees.

Description

Technical Field

[0001] This invention belongs to the field of plant physiological regulation technology, specifically relating to a method for increasing the lignin content in the roots of Lauraceae fruit trees. Background Technology

[0002] In plant taxonomy, avocados belong to the genus *Persea* within the family Lauraceae. While fruit trees within the same family (Lauraceae) may exhibit some differences in physiological metabolism, these differences mainly manifest in metabolic pathways, accumulation of metabolites, and environmental adaptability between different genera. However, seedling plants within the same genus are closely related taxonomically, sharing a high degree of similarity in their genome structure and function. This determines that they share commonalities in physiological metabolic pathways and the accumulation of metabolites.

[0003] As a globally important tropical economic fruit tree, the quality of avocado root development directly determines the plant's growth vigor and lifespan, and also regulates fruit yield and quality through water and nutrient absorption efficiency. In natural cultivation environments, avocado tree roots often exhibit typical developmental defects: the lignification process of the taproot lags significantly behind the above-ground growth, resulting in a weak supporting structure and incomplete development of vascular tissue; lateral root primordia germination frequency is low, elongation rate is slow, and cell differentiation in the root tip meristem is hindered, ultimately forming an inefficient root system structure of "weak taproot - sparse lateral roots." This structural defect is particularly prominent in acidic, infertile soils such as red soil and lateritic red soil in tropical monsoon climates, as well as in sloping environments with frequent seasonal droughts. The insufficiently lignified root cortex is susceptible to infection by pathogenic fungi, while the lack of lateral roots prevents the plant from effectively expanding its water absorption network during the dry season, often leading to leaf wilting, increased fruit drop, and in severe cases, the death of the entire young tree. Currently, the main techniques for promoting root lignification in agricultural production are chemical regulation and fertilization. Chemical regulation relies on auxins such as indolebutyric acid and naphthaleneacetic acid to induce xylem cell differentiation, but its effectiveness is significantly affected by soil pH, organic matter content, and temperature fluctuations, often exhibiting an unstable phenomenon of "short-term growth promotion followed by long-term inhibition." More importantly, neither of these traditional methods fully mobilizes the molecular regulatory mechanisms of avocado root development, lacking targeted solutions for lignification-sensitive varieties due to genotypic differences (such as Hass avocados), and thus failing to meet the demands of modern precision agriculture for environmentally friendly and cost-effective technologies.

[0004] CN116602320A discloses a composition, biological agent, application, and method for promoting lignification of fleshy root systems in fruit trees and / or preventing root rot in fruit trees. This method mainly employs the application of a mixture of several microbial agents and a mixture of several plant extracts to achieve optimal artificial cultivation. CN117223715A discloses a biological pesticide for controlling root rot in avocados; this method aims to achieve optimal cultivation through a single biological pesticide approach. CN118340160 discloses a fungicidal composition for controlling root rot in avocados, still using chemical drugs as a means. Both methods are therapeutic and lack preventative function. CN114793531A discloses a method for cultivating rootstocks for avocados to prevent root rot, but this method has limited effectiveness and is also based on a single method.

[0005] It is evident that existing technologies have failed to effectively address the problem of insufficient lignification of the root systems in avocado trees and other Lauraceae fruit trees. Summary of the Invention

[0006] This invention aims to increase the lignin content in the roots of Lauraceae fruit trees such as avocado trees. It employs a lignin-synthetic nutrient-enhancing solution, directional pulsed electric field treatment to enhance the permeability of epidermal cell membranes, specific wavelength ultraviolet irradiation to activate key enzymes in phenylpropanoid metabolism, and synergistic application of mechanical stress to stimulate and induce vascular tissue differentiation, thereby increasing lignin content in the roots of Lauraceae fruit trees such as avocado trees. This method not only increases the lignin content of the roots and improves root resistance and mechanical strength, but also maintains normal physiological metabolism, providing a new solution for lodging-resistant cultivation and root rot prevention of Lauraceae fruit trees such as avocado trees.

[0007] This invention provides a method for increasing the lignin content in the roots of Lauraceae fruit trees, comprising the following steps:

[0008] A. Shaping: Prune the Lauraceae fruit trees appropriately;

[0009] B. Application of nutrient-enhancing solution: Apply nutrient-enhancing solution to the pruned fruit trees once every 1-3 weeks, with a total of no less than 10 applications, each application using 10-25L; the nutrient-enhancing solution is an aqueous solution containing 0.05wt%-0.5wt% seaweed extract, 0.1wt%-0.5wt% wood vinegar, 0.3wt%-1.0wt% phenylalanine, 0.02wt%-0.2wt% ferulic acid, and 0.05wt%-0.1wt% coniferyl alcohol;

[0010] C. Pulsed electric field treatment: Install a pulse power generator near the fruit tree. With the trunk as the center, insert 1 to 3 electrodes evenly distributed at a distance of 3 to 10 cm from the center of the trunk, and insert 3 to 6 electrodes evenly distributed around the circumference at a distance of 1 / 2 to 3 / 4 from the drip line on the outer edge of the trunk. After 5 minutes of watering, turn on the pulse power generator to stimulate the pulse electric field.

[0011] D. Ultraviolet light source irradiation treatment: Tie a 40-80W ultraviolet lamp to the trunk of the fruit tree. Turn on the ultraviolet lamp to irradiate the tree on the 3rd to 7th day after the pulse electric field treatment is completed.

[0012] E. Mechanical vibration induces lignification of fruit tree roots: Insert 4 to 8 vibration heads evenly distributed around the drip line of the fruit tree as working points. Turn on the vibration heads 1 to 3 hours after the ultraviolet light source irradiation begins and carry out vibration operation.

[0013] F. Fruit fertilizer nutrition management: Apply fruit fertilizer to the pruned fruit trees. The fertilization frequency is once every 2 to 4 months. The fruit fertilizer applied each time is ammonium nitrate phosphate compound fertilizer: potassium sulfate: sodium silicate in a mass ratio of 1.5 to 3: 0.8 to 1.2: 0.8 to 1.2.

[0014] In the above-mentioned method for increasing the lignin content in the roots of Lauraceae fruit trees, steps B to E may be performed only in steps B and D, or only in steps B, C and D, or only in steps B, D and E, or only in steps B, C and E.

[0015] Preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step A, the Lauraceae fruit tree is a fruit tree of the genus *Avocado* in the Lauraceae family.

[0016] More preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step A, the Lauraceae fruit trees are American avocado, Mexican variety, Guatemalan variety, or West Indian variety fruit trees belonging to the genus *Avocado* of the Lauraceae family.

[0017] In the preferred embodiment of the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step A, the Lauraceae fruit tree is the avocado tree.

[0018] Preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step A, the Lauraceae fruit trees are 1-3 year old saplings of Lauraceae fruit trees.

[0019] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step A, after pruning, the tree height is 90-200cm, 3-5 main branches are retained, the angle between the main branches is 100-150°, and the crown is open and umbrella-shaped.

[0020] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step A involves pruning in spring before new buds sprout, when the temperature is above 15℃.

[0021] In the above-mentioned method for increasing the lignin content in the roots of Lauraceae fruit trees, step A involves pruning primarily with light cuts to retain sufficient leaves for photosynthesis.

[0022] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step A involves applying petroleum jelly to the cut ends of branches with a diameter exceeding 1.5 cm to prevent bacterial invasion.

[0023] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step B involves applying the first nutrient-enhancing solution 15–45 days after pruning.

[0024] Preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step B involves applying the foliar spray every 2 to 3 weeks.

[0025] Preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step B involves a total of 20 to 80 applications of foliar spraying.

[0026] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step B involves applying the solution on a sunny morning, avoiding strong sunlight.

[0027] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step B, during drenching, the nutrient enhancement solution is evenly sprayed onto the soil surface around the roots of the fruit trees and the back of the leaves.

[0028] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step B, the soil should be kept moist but not waterlogged during application.

[0029] Preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, 1-2 electrodes are evenly inserted at a distance of 3-10 cm from the center of the trunk, and 4-5 electrodes are evenly inserted on the circumference at a distance of 1 / 2 to 3 / 4 from the drip line on the outer edge of the trunk.

[0030] More preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, an electrode is inserted at a distance of 3 to 10 cm from the center of the trunk, and an electrode is inserted at four points on the circumference at three, six, nine and twelve o'clock, respectively, at a distance of 1 / 2 to 3 / 4 from the drip line on the outer edge of the trunk.

[0031] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, the electrode is inserted to a depth of 10–30 cm.

[0032] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, the electrode is a graphite electrode or a titanium electrode with a diameter of 3-8 cm.

[0033] In the method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, the electrode is perpendicular to the ground at a 90° angle.

[0034] In the method for increasing the lignin content in the roots of Lauraceae fruit trees, step C controls the ratio of the sum of the surface areas of the electrodes at the center of the trunk to the sum of the surface areas of the electrodes on the circumference to be 1±0.1:1±0.1.

[0035] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, during pulsed electric field stimulation, the output voltage of the voltage pulse generator is 5-20 kV, and the pulse width is 60-120 ms.

[0036] In the method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, the pulse interval of the voltage pulse generator during pulsed electric field stimulation is 0.2 to 2 seconds.

[0037] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step C involves a pulsed electric field stimulation time of 1200–2400 s per cycle.

[0038] In the method for increasing the lignin content in the roots of Lauraceae fruit trees, in step C, after each round of pulsed electric field stimulation is completed, the anode and cathode are reversed in the next round of pulsed electric field stimulation.

[0039] In the method described above for increasing the lignin content in the roots of Lauraceae fruit trees, in step D, the length of the ultraviolet lamp is 20–40 cm.

[0040] Preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step D involves attaching an ultraviolet lamp to the middle of the canopy of the tree trunk.

[0041] In the method for increasing the lignin content in the roots of Lauraceae fruit trees, step D involves using an ultraviolet lamp wrapped with a 0.01–0.03 mm thick polystyrene film.

[0042] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step D involves ultraviolet irradiation under the following conditions: irradiation for 30-60 minutes followed by a 10-20 minute break, with a total irradiation time of 6-10 hours.

[0043] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step E, the vibrating head is inserted into the ground to a depth of 20-40 cm.

[0044] Preferably, in the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step E, a vibrating head is inserted as a working point at the 2 o'clock, 4 o'clock, 6 o'clock, 8 o'clock, 10 o'clock and 12 o'clock directions on the circumference of the drip line of the fruit tree.

[0045] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step E, during vibration operation, the vibration frequency is 2000-8000 times / minute, the amplitude is 2-5mm, and the vibration time is 15-60s / operation point.

[0046] In the method for increasing the lignin content in the roots of Lauraceae fruit trees, in step E, during vibration operation, each vibrating head performs vibration operation sequentially and continuously without the need for interval operation time.

[0047] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, step F involves applying fruit fertilizer for the first time on the day of pruning or within 3 days.

[0048] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step F, the total mass of ammonium nitrate phosphate compound fertilizer, potassium sulfate, and sodium silicate applied each time is 0.2 to 0.3 kg.

[0049] In the above method for increasing the lignin content in the roots of Lauraceae fruit trees, in step F, when applying the fertilizer, the fruit fertilizer is prepared into a 0.3-0.7% concentration water-soluble fertilizer and applied by drip irrigation, with the drip irrigation system arranged in a circle 5-15cm inside the drip line.

[0050] The beneficial effects of this invention are:

[0051] This invention employs a nutrient-enhancing solution for lignin synthesis precursors, followed by directional pulsed electric field treatment to enhance the permeability of root epidermal cell membranes in fruit trees, thus promoting the transport of lignin precursor substances. After the nutrient transport accumulation period, specific wavelength ultraviolet irradiation is used to activate the activity of key enzymes in phenylpropanone metabolism, improving the synthesis efficiency of phenolic compounds. Simultaneously, mechanical stress stimulation is applied to induce vascular tissue differentiation, guiding lignin deposition and constructing a carbon metabolism network conducive to lignin biosynthesis. This can improve the disease resistance of the roots of Lauraceae fruit trees such as avocados, increasing root lignin content by more than 30% and reducing the risk of infection by pathogens such as root rot and nematodes. Lignified roots have enhanced water retention capacity, adapting to drought, saline-alkali, and other adverse soil conditions. The simultaneously applied mechanical stress stimulation also increases the tensile strength of the plant by more than 45%, reducing root breakage caused by wind damage or soil movement, and increasing root density, expanding the nutrient absorption range. The drip irrigation and fertilization strategy guides the roots to extend into deeper soil layers, enhancing plant stability and utilization of deeper nutrients, avoiding the problem of excessive nitrogen inhibiting lignin synthesis.

[0052] The method of this invention is used to treat Lauraceae fruit trees such as avocado trees to enhance the root system's water retention capacity, increase the plant's tensile strength, reduce root breakage, and provide precise water and fertilizer treatment. This reduces fertilizer, pesticide, and labor management costs by 15% to 25%. The use of physical measures reduces the use of chemical fertilizers and pesticides, lowers the risk of soil pollution, and improves the quality of fruits from Lauraceae fruit trees such as avocado trees. Attached Figure Description

[0053] Figure 1 The image shows a typical avocado tree of the present invention; where a is Example 1, b is the naturally grown group of Example 1, c is the control group 1.1, d is the control group 1.2, e is the control group 1.3, and f is the control group 1.4.

[0054] Figure 2 This is a typical root feature diagram of the avocado tree of the present invention; wherein, a is Example 1, b is the natural growth group of Example 1, c is the control group 1.1, d is the control group 1.2, e is the control group 1.3, and f is the control group 1.4. Detailed Implementation

[0055] Specifically, a method for increasing the lignin content in the roots of Lauraceae fruit trees such as avocado trees includes the following steps:

[0056] A. Shaping: Prune the Lauraceae fruit trees appropriately;

[0057] B. Application of nutrient-enhancing solution: Apply nutrient-enhancing solution to the pruned fruit trees once every 1-3 weeks, with a total of no less than 10 applications, each application using 10-25L; the nutrient-enhancing solution is an aqueous solution containing 0.05wt%-0.5wt% seaweed extract, 0.1wt%-0.5wt% wood vinegar, 0.3wt%-1.0wt% phenylalanine, 0.02wt%-0.2wt% ferulic acid, and 0.05wt%-0.1wt% coniferyl alcohol;

[0058] C. Pulsed electric field treatment: Install a pulse power generator near the fruit tree. With the trunk as the center, insert 1 to 3 electrodes evenly distributed at a distance of 3 to 10 cm from the center of the trunk, and insert 3 to 6 electrodes evenly distributed around the circumference at a distance of 1 / 2 to 3 / 4 from the drip line on the outer edge of the trunk. After 5 minutes of watering, turn on the pulse power generator to stimulate the pulse electric field.

[0059] D. Ultraviolet light source irradiation treatment: Tie a 40-80W ultraviolet lamp to the trunk of the fruit tree. Turn on the ultraviolet lamp to irradiate the tree on the 3rd to 7th day after the pulse electric field treatment is completed.

[0060] E. Mechanical vibration induces lignification of fruit tree roots: Insert 4 to 8 vibration heads evenly distributed around the drip line of the fruit tree as working points. Turn on the vibration heads 1 to 3 hours after the ultraviolet light source irradiation begins and carry out vibration operation.

[0061] F. Fruit fertilizer nutrition management: Apply fruit fertilizer to the pruned fruit trees. The fertilization frequency is once every 2 to 4 months. The fruit fertilizer applied each time is ammonium nitrate phosphate compound fertilizer: potassium sulfate: sodium silicate in a mass ratio of 1.5 to 3: 0.8 to 1.2: 0.8 to 1.2.

[0062] This invention comprises a spatiotemporal coupling scheme of four treatments: nutrient enhancement solution application, pulsed electric field treatment, ultraviolet light irradiation treatment, and mechanical vibration. The nutrient enhancement solution is used to supplement lignin synthesis precursors; the pulsed electric field treatment aims to transport as many precursors as possible into the seedlings; ultraviolet light irradiation activates key rate-limiting enzymes in the lignin synthesis pathway; and mechanical vibration stimulates the seedlings' need for reinforcement. The lignin nutrient enhancement solution application and ultraviolet light irradiation treatment are macroscopic rate-limiting steps in lignin synthesis. Excessive lignin synthesis precursors are necessary for the synthesis of excessive lignin. The activation of rate-limiting enzymes in the lignin synthesis pathway under the environmental factors of ultraviolet irradiation further promotes excessive lignin synthesis. Therefore, this invention can choose to perform only step B (lignin nutrient enhancement solution application) and step D (ultraviolet light irradiation treatment) to achieve a certain degree of increase in root lignin content. Alternatively, this invention can choose to perform only step B (lignin nutrient enhancement solution application), step C (pulsed electric field treatment), and step D (ultraviolet light irradiation treatment) to achieve a further increase in root lignin content. Simultaneously, mechanical vibration activates the phenylpropane pathway through the JA pathway, which indirectly benefits the excessive synthesis of lignin. Therefore, this invention can choose to perform only step B (lignin nutrient enhancement liquid application), step D (ultraviolet light irradiation treatment), and step E (mechanical vibration induction of fruit tree root lignification), or only step B (lignin nutrient enhancement liquid application), step C (pulse electric field treatment), and step E (mechanical vibration induction of fruit tree root lignification), which can also achieve a certain degree of increase in root lignin content. Therefore, in this invention, steps B to E can be performed only in steps B and D, or only in steps B, C, and D, or only in steps B, D, and E, or only in steps B, C, and E (it should be noted that when a certain step is not performed, the starting timing of the other steps can be performed as described above or adjusted accordingly. For example, when only steps B, C, and D are performed, step D is performed by turning on the ultraviolet lamp for ultraviolet irradiation on the 3rd to 7th day after the application; another example is the control group 1.4, which turned on the vibrator for vibration operation on the 5th day after the application).

[0063] Avocado belongs to the genus *Persea* within the family Lauraceae in plant taxonomy. While fruit trees within the same family (Lauraceae) may exhibit certain differences in physiological metabolism, primarily in metabolic pathways, metabolite accumulation, and environmental adaptability between different genera, seedling plants within the same genus share close taxonomic relationships and exhibit high similarity in their genome structure and function. This determines their commonalities in physiological metabolic pathways and metabolite accumulation. Therefore, the method of this invention can be applied to increase the lignin content in the roots of Lauraceae fruit trees. Furthermore, this method can be applied to other species (American avocado) and varieties within the genus *Persea* (including Mexican, Guatemalan, and West Indian varieties). This method is most suitable for increasing the lignin content in the roots of avocado trees.

[0064] In step A of this invention, although this invention can also increase the lignin content of mature fruit trees, the growth of mature fruit trees has already reached its final stage, and the effect of improving the mechanical strength of their branches and the effect of increasing lignin content are not as obvious as those of young trees. Therefore, it is preferable to select young Lauraceae fruit trees, specifically 1-3 year old young Lauraceae fruit trees.

[0065] In step A of this invention, after pruning, two-year-old saplings with a height of 90-200cm and smooth, wrinkle-free bark are selected. During pruning, 3-5 main branches are retained, with an angle of approximately 100-150° between the main branches, resulting in an open, umbrella-shaped crown. Because seedlings in this state have a certain degree of lignification and relatively mature root development, they exhibit relatively strong resistance to adverse conditions. This avoids the problems of excessively tall seedlings being prone to lodging and high transpiration water consumption, or excessively short seedlings resulting in weak root systems and insufficient nutrient reserves. These seedlings have sufficient photosynthetic accumulation and well-developed vascular bundles, enabling efficient transport of water and nutrients. They typically have well-developed taproots, numerous lateral roots, and a good foundation for lignin deposition. Retaining 3-5 main branches not only balances nutrient distribution but also concentrates nutrient supply by limiting the number of main branches, preventing excessive branch growth that leads to competitive growth and competition for lignin synthesis. The approximately 100-150° angle between the main branches improves light penetration, and the open angle prevents branch overlap, increasing light penetration within the canopy and enhancing leaf photosynthetic efficiency. Furthermore, the low tree height facilitates manual management (pruning, spraying, harvesting), reducing operational risks and costs associated with excessive tree height. The open, umbrella-shaped canopy increases the effective leaf area index, improves overall photosynthetic yield, and reduces the risk of sunburn. It also enhances air circulation within the canopy, reduces humidity, and inhibits fungal diseases such as Phytophthora blight and scab. Pruning should be done in spring before new buds emerge, when temperatures are consistently above 15℃. Light pruning is recommended, retaining enough leaves to maintain photosynthesis. Larger cuts (over 1.5cm in diameter) should be coated with petroleum jelly to prevent pathogen invasion.

[0066] In step B of this invention, the wounds on the fruit trees have generally healed by 15 to 45 days after pruning, and the trees have entered a period of full-speed normal growth. Therefore, the first application of nutrient-enhancing liquid should be started 15 to 45 days after pruning.

[0067] In step B of this invention, a nutrient-enhancing solution is applied via drenching. Compared to ordinary spraying nutrient solutions, this invention uses seaweed extract and wood vinegar, which are natural products that provide numerous trace elements needed for the growth of avocado trees and other Lauraceae fruit trees. Phenylalanine, ferulic acid, and coniferyl alcohol are precursors for lignin synthesis. Phenylalanine is the starting substrate for lignin synthesis, ferulic acid is the most important intermediate product in lignin synthesis, and coniferyl alcohol is the main monomer of G-type lignin, which can directly polymerize to form lignin without the complex enzymatic reaction via the phenylpropane pathway. In step B of this invention, the preferred drenching frequency is once every 2-3 weeks; the preferred total number of drenching applications in step B is 20-80. As the tree age increases, the required amount of nutrient solution may increase. Those skilled in the art can appropriately increase the amount of nutrient solution according to the actual situation and the tree age. For example, the total volume of each application in the second year can be increased by 5-20% compared to the first year.

[0068] In step B of this invention, the application time is selected on a sunny morning, avoiding strong sunlight. When applying the solution, it should be evenly sprayed on the soil surface around the roots of the seedlings of Lauraceae fruit trees such as avocado trees and the back of the leaves, keeping the soil moist but not waterlogged.

[0069] Compared with traditional cultivation methods, the pulsed electric field treatment used in step C of this invention directly activates the response of root epidermal cells of Lauraceae fruit trees such as avocado trees through physical electrical signals. The pulsed electrical signals cause the cell wall cellulose microfibrils to align in a specific direction, providing a framework for lignin deposition. At the same time, it upregulates COMT gene expression, promotes the synthesis of syringyl lignin monomers, and accelerates the absorption of lignin cross-linking elements such as boron and silicon.

[0070] In step C of this invention, after each watering, a pulse power generator is installed near the fruit tree, and electrodes are inserted. The pulse power generator and electrodes are detachable and movable devices, installed when in use and stored away after use. As the tree crown grows, the drip line automatically expands outward, and the position of the inserted electrodes moves according to the tree's growth and the drip line. In step C, preferably, 1-2 electrodes are evenly inserted at a distance of 3-10 cm from the center of the trunk, and 4-5 electrodes are evenly inserted on the circumference at 1 / 2 to 3 / 4 of the distance from the outer edge of the drip line; more preferably, 1 electrode is inserted at a distance of 3-10 cm from the center of the trunk, and 1 electrode is inserted at each of the four points (3 o'clock, 6 o'clock, 9 o'clock, and 12 o'clock) on the circumference at 1 / 2 to 3 / 4 of the distance from the outer edge of the drip line. If the number of electrodes is too small, for example, only two electrodes are inserted on the circumference, the roots in some directions may not receive stimulation, resulting in a poorer effect.

[0071] In step C of this invention, the electrode is inserted to a depth of 10–30 cm. In step C, the electrode is a graphite electrode or a titanium electrode with a diameter of 3–8 cm. In step C, the electrode is perpendicular to the ground at a 90° angle. In step C, the ratio of the sum of the surface areas of the electrodes at the center of the trunk to the sum of the surface areas of the electrodes on the circumference is controlled to be 1 ± 0.1 : 1 ± 0.1. In this invention, maintaining a substantially consistent current density between the central electrode and the circumferential electrodes is beneficial for stimulating various points on the roots of the fruit tree, and the subsequent electrode flipping strategy further enhances root stimulation.

[0072] In step C of this invention, the trees begin to absorb nutrients generally 15 minutes to several hours after application, depending on the specific variety and the plant's growth stage. In this invention, the nutrient solution has already soaked into the leaves and near the roots 5 minutes after application, awaiting electrical stimulation to expand cell membrane channels. Therefore, electrical stimulation can be performed 5 minutes to several hours after application (e.g., 1 hour or 2 hours) by turning on the pulse power generator; however, it is generally not advisable to delay for too long to avoid significant nutrient solution loss.

[0073] In step C, during pulsed electric field stimulation, the output voltage of the voltage pulse generator is 5–20 kV, the pulse width is 60–120 ms, and the pulse interval of the voltage pulse generator is 0.2–2 s. The duration of pulsed electric field stimulation for each fruit tree in each round is 1200–2400 s. In step C, after each round of pulsed electric field stimulation, the anode and cathode are reversed for the next round (for example, after the first application, the center of the trunk is anode and the circumference is cathode; after the second application, the center of the trunk is cathode and the circumference is anode; after the third application, the center of the trunk is anode and the circumference is cathode, and so on; and vice versa).

[0074] Compared with traditional cultivation methods, step D of this invention uses a specific ultraviolet light source for irradiation treatment. This ultraviolet light source is ultraviolet light filtered through a 0.01-0.03 mm thick polystyrene film, mainly UV-B plus a small amount of UV-A, and almost no UV-C. This light source activates the MAPK signaling pathway through photosensitive pigments (UVR8 receptors), and works synergistically with Ca²⁺ signaling to increase lignin content by 20%-30% (compared to only 5%-15% by traditional methods).

[0075] In step D of this invention, 3 to 7 days after each pulsed electric field treatment, a commercially available ultraviolet lamp is tied to the trunk of the fruit tree. The ultraviolet lamp is a detachable and movable device, installed when in use and returned to the storage room after use. The center position of the ultraviolet lamp is adjusted according to the growth of the tree to ensure that as many leaves as possible are irradiated.

[0076] In step D of this invention, the ultraviolet lamp is 20-40 cm long. In step D of this invention, the ultraviolet lamp is tied to the middle of the canopy of the fruit tree trunk. In step D of this invention, the ultraviolet lamp is an ultraviolet lamp wrapped with a 0.01-0.03 mm thick polystyrene film. In step D of this invention, the ultraviolet irradiation operating conditions are: irradiation for 30-60 minutes followed by a 10-20 minute break, with a total irradiation time of 6-10 hours per session.

[0077] Compared to traditional cultivation methods, step E of this invention uses mechanical vibration to induce root lignification in Lauraceae fruit trees such as avocado. Mechanical vibration may induce the synthesis of jasmonic acid (JA) in the plant, and jasmonic acid is one of the key hormones regulating lignin synthesis. Mechanical vibration treatment activates the JA signaling pathway, thereby promoting the expression of genes related to the phenylpropane pathway (the core pathway of lignin synthesis). The physical action of the vibrator loosens the soil around the roots, increases oxygen content, and promotes root respiration. Sufficient energy supply is fundamental to maintaining the activity of lignin-synthesizing enzymes (such as peroxidase and laccase). The mechanical stress generated by vibration directly stimulates the need for reinforcement of root cell walls.

[0078] In step E of this invention, 1-3 hours after each ultraviolet light irradiation begins, vibrating heads are inserted evenly around the drip line of the fruit tree as working points. The vibrating heads are detachable and movable devices, installed when in use and returned to the storage room after use. As the tree canopy grows, the drip line position automatically expands outward, and the position of the inserted vibrating heads moves according to the specific drip line of the tree's growth.

[0079] In step E of this invention, the vibrating head is inserted into the ground to a depth of 20-40 cm. Preferably, in step E, one vibrating head is inserted at each of the following locations on the circumference of the fruit tree's drip line: at the 2, 4, 6, 8, 10, and 12 o'clock positions. During vibration operation in step E, the vibration frequency is 2000-8000 times / minute, the amplitude is 2-5 mm, and the vibration time is 15-60 seconds per operation point. In step E, each vibrating head performs vibration operation sequentially and continuously without any interval between operations.

[0080] Compared to traditional cultivation methods, step F of this invention utilizes a fruit fertilizer nutrient management system for Lauraceae fruit trees such as avocado. This formula combines ammonium nitrate phosphate compound fertilizer and potassium sulfate to address both macro- and micronutrient needs. Sulfate ions are components of cysteine ​​and methionine, influencing glutathione synthesis, reducing reactive oxygen species damage to cells, and ensuring the normal functioning of the phenylpropanoid pathway. The silicate ions in sodium silicate are deposited in the cell wall as silicic acid, enhancing mechanical strength, reducing stress hormones (such as ethylene) produced by the roots due to mechanical stress, and allowing more resources to be allocated to lignin synthesis.

[0081] In step F of this invention, the fruit fertilizer is applied for the first time on the day of pruning or within 3 days. In step F of this invention, the total mass of ammonium nitrate phosphate compound fertilizer, potassium sulfate, and sodium silicate applied each time is 0.2–0.3 kg. In step F of this invention, the fruit fertilizer is prepared as a 0.3–0.7% solution and applied via drip irrigation, with the drip irrigation system arranged in a circle 5–15 cm inside the drip line. While the fertilization management in step F of this invention is beneficial for promoting lignin synthesis during the lignin synthesis period, it is not suitable for the nutritional needs of fruit production. Therefore, after the completion of the method of this invention, conventional fertilization measures should be adopted.

[0082] In this invention, a pulsed electric field of a certain intensity can alter the dielectric properties of the cell membrane lipid bilayer, inducing membrane depolarization or hyperpolarization, thereby activating voltage-gated ion channels, promoting the activation of calcium signaling pathways in root tip meristem cells, inducing upregulation of cyclin gene expression, and driving the differentiation of meristematic cells into xylem mother cells. Ultraviolet radiation of a specific wavelength activates the photoreceptor UVR8 protein, initiating a downstream signaling cascade. On the one hand, it promotes the binding of the MYB transcription factor family to the promoters of lignin synthesis-related genes; on the other hand, it specifically enhances the enzyme activities of phenylalanine ammonia-lyase (PAL), peroxidase (POD), and cinnamyl alcohol dehydrogenase (CAD) through reactive oxygen species (ROS)-mediated redox signals. To cope with the stress of ultraviolet radiation, plants may increase the synthesis of certain antioxidants, such as flavonoids and phenolic compounds, which are related to the lignin synthesis pathway. Mechanical vibration regulation technology simulates natural wind applied to trees, creating mechanical stress on the plant roots, activating mechanosensitive ion channels within plant cells, triggering the cell wall-cell membrane-cytoskeleton signaling network, inducing tubulin rearrangement and directional transport of synthase complexes, thereby promoting the differentiation of vascular cambium cells into xylem vessels.

[0083] The key to overcoming the bottleneck of existing single technologies lies in constructing a dynamic regulation system with multi-physics coupling. The system includes a pulsed electric field generator, which reshapes the cell membrane potential through a root zone electrode array to provide an electrochemical driving force for the transmembrane transport of lignin monomers; a specific ultraviolet light source, which initiates directional irradiation according to the spatiotemporal peak period of lignin synthesis to activate the phenylalanine metabolic pathway; and a mechanical vibration mode, which transmits mechanical stress to the root tip elongation zone through a deep vibration rod to trigger tubulin reorganization and xylem mother cell differentiation.

[0084] The present invention will be further described in detail below through embodiments, but the scope of protection of the present invention is not limited to the embodiments described herein.

[0085] Example 1: Treatment of Pinkerton avocado trees

[0086] 1. Selection and shaping of seedlings: Select two-year-old saplings with a height of 150cm, retain 4 main branches with an angle of about 120° between the main branches, and open the crown in an umbrella shape. The pruning period is in spring before the new buds sprout and the temperature is stable above 15℃. Light pruning is the main method, retaining enough leaves to maintain photosynthesis. Apply petroleum jelly to larger cuts to prevent the invasion of pathogens.

[0087] 2. Nutrient Enhancement Solution Drenching: The nutrient enhancement solution is an aqueous solution with a mass fraction of 0.1% seaweed extract, 0.2% wood vinegar, 0.7% phenylalanine, 0.05% ferulic acid and 0.08% conifer alcohol. Drenching treatment should begin 30 days after pruning, and the frequency should be once every two weeks. Each time, spray 15L per plant. Drenching should be done on a sunny morning, avoiding strong sunlight. When drenching, spray evenly on the soil surface around the roots of the avocado seedlings and on the back of the leaves.

[0088] 3. Pulsed electric field treatment: Install a pulse power generator near the avocado tree. With the trunk as the center, insert an electrode 5cm away from the center. Insert electrodes at four points (3, 6, 9, and 12 o'clock) around the circumference, two-thirds of the way from the drip line on the outer edge of the trunk. The electrode insertion depth is 20cm, and the electrodes are perpendicular to the ground at 90°. Stimulation time: 5 minutes after each application. The voltage output of the pulse generator is 10kV. The electrodes are graphite electrodes with a diameter of 5cm. The pulse width is 80ms, and the pulse interval is 0.5s. The stimulation time for each avocado tree is 1800s. The discharge surface area of ​​the electrode at the center of the trunk is approximately 1:1 to the sum of the discharge surface areas of the four electrodes on the circumference. After each round of pulse stimulation, the anode and cathode are reversed for the next round of pulse stimulation.

[0089] 4. Ultraviolet light source irradiation treatment: Tie a 30cm long, 60W ultraviolet lamp to the trunk of the avocado tree, in the middle of the canopy. The ultraviolet irradiation operation conditions are: irradiate for 45 minutes and then stop for 15 minutes. The irradiation time is 8 hours. The ultraviolet light source is a commercially available ultraviolet lamp wrapped with a 0.02mm thick polystyrene film. The ultraviolet treatment time point is 5 days after each pulse electric field treatment.

[0090] 5. Mechanical vibration-induced root lignification in avocado trees: A vibrator was used to operate along the drip line of the tree canopy, with 6 operating points arranged around the trunk at the 2 o'clock, 4 o'clock, 6 o'clock, 8 o'clock, 10 o'clock, and 12 o'clock positions. The vibrator head was inserted into the ground to a depth of 30cm, with a vibration frequency of 4000 times / minute, an amplitude of 3mm, and a vibration time of 30s per operating point. The vibration operation was started 2 hours after each UV irradiation session.

[0091] 6. Avocado fertilizer nutrient management: After pruning, apply ammonium nitrate phosphate compound fertilizer: potassium sulfate: sodium silicate in a mass ratio of 2:1:1 to each plant, 0.25 kg each time, once every 3 months, to prepare a 0.5% concentration of water fertilizer, and apply it by drip irrigation, with the drip irrigation system arranged in a circle 10 cm inside the drip line.

[0092] Control group 1.1: Only drenching was used (compared to implementation case 1), that is, only steps 1, 2 and 6 were performed.

[0093] Control group 1.2: Only pulsed electric field stimulation was used (compared to implementation case 1), that is, only steps 1, 3 and 6 were performed.

[0094] Control group 1.3: Only ultraviolet light irradiation was used (compared to implementation case 1), that is, only steps 1, 4 and 6 were performed.

[0095] Control group 1.4: Mechanical stimulation was used only (compared to implementation case 1), i.e. only steps 1, 5 and 6 were performed.

[0096] Natural growth group: No measures were taken, steps 1-6 were not performed, and the plants grew naturally.

[0097] Two years after planting avocado seedlings using the above method, relevant indicators were tested.

[0098] Tensile testing of avocado roots was conducted using a universal testing machine. The test site was Panzhihua University. Avocado roots dug 15cm into the soil were selected as test subjects, and mechanical damage to the root system should be avoided during the digging process. Fresh, disease-free, straight root segments with minimal curvature were selected and cut into 100mm lengths using pruning shears. The diameter of the root segment was measured using vernier calipers. Since the root cross-section is not a uniformly regular circle, measurements were taken at three different locations: the root tip and the middle of the root, and the average value was taken as the diameter of the root segment. The tensile test conditions were set as follows: root diameter 5–6mm; root segment length 100mm; tensile rate 10mm / min; root bark was preserved during the test. The lignin content was determined using the acid-insoluble lignin content determination method (GB / T 2677.8-1994); root sample collection was conducted using the same method as the tensile test. The density of avocado tree root samples was determined according to the national standard "Method for Determination of Wood Density" (GB / T 1933-2009). The root sample collection method was the same as that for tensile testing.

[0099] Root rot infection experiments were conducted at the Panzhihua Academy of Agricultural and Forestry Sciences and Panzhihua Panduoduo Agricultural Technology Co., Ltd., Sichuan Province. *Fusarium oxysporum* was selected as the pathogenic strain for root rot. During the experiment, the strain was activated using PDA culture medium without agar at 28℃. The inoculum size was 10%, the culture time was 3 days, and the shaking speed was 50 r / min. The viable bacterial concentration in the resulting bacterial suspension was determined to be approximately 1.546 × 10⁻⁶. 5 The inoculation rate was [number] cells / mL. Root rot inoculation was performed using the field root-injury method. The specific procedure was as follows: without disturbing the normal growth of the avocado plant, the soil around the plant's root system was dug up, and a wound approximately 2 cm long was made at the base of the root with a utility knife. The wound was then immersed in the prepared bacterial suspension for 2 minutes, followed immediately by covering with soil and watering thoroughly to promote pathogen infection. This experiment included six treatment groups, with 10 plants in each group: the example group (comprehensive treatment), the natural growth control group, the drenching treatment group, the pulsed electric field stimulation treatment group, the ultraviolet lamp irradiation treatment group, and the mechanical vibration stimulation treatment group. Disease severity, root lignification degree evaluation, and plant growth assessment were conducted on days 15, 30, 45, 60, and 75 post-inoculation. Disease severity was graded into four levels: healthy, mildly infected, moderately infected, and severely infected, used to systematically evaluate the effects of different treatments on the development of root rot.

[0100] Table 1 Results of control treatments for Pinkerton avocado trees

[0101]

[0102] The comparative data from this embodiment show that the individual application of nutrient-enhancing liquid, pulsed electric field treatment, ultraviolet lamp irradiation, and mechanical stress induction has limited effect on improving the resistance to root rot and promoting root development in Pinkerton avocado seedlings, and is lower than the combined effect of multiple treatments coupled in a specific spatiotemporal pattern. The combined treatment strategy can more effectively increase the lignin content of avocado seedling roots, reaching 31.3%, which is about 35.5% higher than the lignin content of naturally grown seedlings. The root tensile strength of the embodiment reached 72.2 MPa, which is about 43.8% higher than that of naturally grown seedlings, and the root density of the embodiment was about 18.4% higher than that of naturally grown seedlings. The embodiment enhanced the resistance of avocados to root rot induced by Phytophthora camphorata. During the 75-day observation period, the embodiment was rated as very healthy, while the other control groups were infected to varying degrees. This spatiotemporal coupled treatment method significantly improves the tensile strength and root density of the root system, promotes the root lignification process, and thus enhances the plant's adaptability to abiotic stresses such as drought and salinity. At the same time, this treatment helps reduce the risk of root breakage caused by wind damage or soil displacement, and expands the range of root absorption of soil nutrients and water, thereby improving the overall growth stability and adaptability of the plant.

[0103] Example 2: Treatment of Has avocado trees

[0104] 1. Selection and shaping of seedlings: Select two-year-old saplings with a height of 140cm, retain 4 main branches with an angle of about 120° between the main branches, and open the crown in an umbrella shape. The pruning period is in spring before the new buds sprout and the temperature is stable above 15℃. Light pruning is the main method, retaining enough leaves to maintain photosynthesis. Apply petroleum jelly to larger cuts to prevent the invasion of pathogens.

[0105] 2. Nutrient Enhancement Solution Drenching: The nutrient enhancement solution is an aqueous solution with a mass fraction of 0.2% seaweed extract, 0.3% wood vinegar, 0.6% phenylalanine, 0.06% ferulic acid and 0.09% conifer alcohol. Drenching treatment should begin 30 days after pruning, and the frequency should be once every two weeks. Spray 20L per plant. Drenching should be done on a sunny morning, avoiding strong sunlight. When drenching, spray evenly on the soil surface around the roots of the avocado seedlings and on the back of the leaves.

[0106] 3. Pulsed Electric Field Treatment: Install a pulse power generator near the avocado tree. With the trunk as the center, insert an electrode 5cm away from the center. Insert electrodes at four points (3, 6, 9, and 12 o'clock) around the circumference, two-thirds of the way from the drip line on the outer edge of the trunk. The electrode insertion depth is 25cm, and the electrodes are perpendicular to the ground at 90°. Stimulation time: 5 minutes after each application. The voltage output of the pulse generator is 10kV. The electrodes are graphite electrodes with a diameter of 5cm. The pulse width is 100ms, and the pulse interval is 1s. The stimulation time for each avocado tree is 1800s. The discharge surface area of ​​the electrode at the center of the trunk is approximately 1:1 to the sum of the discharge surface areas of the four electrodes on the circumference. After each round of pulse stimulation, the anode and cathode are reversed for the next round of pulse stimulation.

[0107] 4. Ultraviolet light source irradiation treatment: Tie a 30cm long, 60W ultraviolet lamp to the trunk of the avocado tree, in the middle of the canopy. The ultraviolet irradiation operation conditions are: irradiate for 45 minutes and then stop for 15 minutes. The irradiation time is 8 hours. The ultraviolet light source is a commercially available ultraviolet lamp wrapped with a 0.02mm thick polystyrene film. The ultraviolet treatment time point is 5 days after each pulse electric field treatment.

[0108] 5. Mechanical vibration-induced root lignification in avocado trees: A vibrator was used to operate along the drip line of the tree canopy, with 6 operating points arranged around the trunk at the 2 o'clock, 4 o'clock, 6 o'clock, 8 o'clock, 10 o'clock, and 12 o'clock positions. The vibrator head was inserted into the ground to a depth of 30cm, with a vibration frequency of 5000 times / minute, an amplitude of 4mm, and a vibration time of 30s per operating point. The vibration operation was started 2 hours after each UV irradiation session.

[0109] 6. Avocado fertilizer nutrient management: Apply ammonium nitrate phosphate compound fertilizer: potassium sulfate: sodium silicate in a mass ratio of 2:1:1 per plant, 0.25 kg per application, once every 3 months, to prepare a 0.5% concentration of water-soluble fertilizer, and apply by drip irrigation, with the drip irrigation system arranged in a circle 10 cm inside the drip line.

[0110] Control group 2.1: Only drenching was used (compared to implementation case 2), that is, only steps 1, 2 and 6 were performed.

[0111] Control group 2.2: Only pulsed electric field stimulation was used (compared to implementation case 2), that is, only steps 1, 3 and 6 were performed.

[0112] Control group 2.3: Only ultraviolet light irradiation was used (compared to implementation case 2), that is, only steps 1, 4 and 6 were performed.

[0113] Control group 2.4: Mechanical stimulation only (compared to implementation case 2), i.e. only steps 1, 5 and 6 were performed.

[0114] Natural growth group: No measures were taken, steps 1-6 were not performed, and the plants grew naturally.

[0115] Two years after planting avocado seedlings using the above method, relevant indicators were tested. The testing method of Example 1 was used, which will not be elaborated here.

[0116] Table 2 Results of the control treatment of Has avocado trees

[0117]

[0118] The comparative data from this embodiment show that the individual application of nutrient-enhancing liquid, pulsed electric field treatment, ultraviolet lamp irradiation, and mechanical stress induction has limited effect on improving the resistance to root rot and promoting root development in Hass avocado seedlings, and is lower than the combined effect of multiple treatments coupled in a specific spatiotemporal pattern. The combined treatment strategy can more effectively increase the lignin content of avocado seedling roots, reaching 33.3%, which is about 30.1% higher than the lignin content of naturally grown seedlings. The root tensile strength of the embodiment reached 65.9 MPa, which is about 46.1% higher than that of naturally grown seedlings, and the root density of the embodiment was about 16.7% higher than that of naturally grown seedlings. The embodiment enhanced the resistance of avocados to root rot induced by Phytophthora camphorata. During the 75-day observation period, the embodiment was rated as very healthy, while the other control groups were infected to varying degrees. This spatiotemporal coupled treatment method significantly improves the tensile strength and root density of the root system, promotes the root lignification process, and thus enhances the plant's adaptability to abiotic stresses such as drought and salinity. At the same time, this treatment helps reduce the risk of root breakage caused by wind damage or soil displacement, and expands the range of root absorption of soil nutrients and water, thereby improving the overall growth stability and adaptability of the plant.

[0119] Example 3: Treatment of Fulte avocado trees

[0120] 1. Selection and shaping of seedlings: Select two-year-old saplings with a height of 140cm, retain 4 main branches with an angle of about 120° between the main branches, and open the crown in an umbrella shape. The pruning period is in spring before the new buds sprout and the temperature is stable above 15℃. Light pruning is the main method, retaining enough leaves to maintain photosynthesis. Apply petroleum jelly to larger cuts to prevent the invasion of pathogens.

[0121] 2. Nutrient Enhancement Solution Drenching: The nutrient enhancement solution is an aqueous solution with a mass fraction of 0.3% seaweed extract, 0.4% wood vinegar, 0.8% phenylalanine, 0.09% ferulic acid and 0.07% conifer alcohol. Drenching treatment should begin 30 days after pruning, and the frequency should be once every two weeks. Each time, spray 15L per plant. Drenching should be done on a sunny morning, avoiding strong sunlight. When drenching, spray evenly on the soil surface around the roots of the avocado seedlings and on the back of the leaves.

[0122] 3. Pulsed Electric Field Treatment: Install a pulse power generator near the avocado tree. With the trunk as the center, insert an electrode 5cm away from the center. Insert electrodes at four points (3, 6, 9, and 12 o'clock) around the circumference, two-thirds of the way from the drip line on the outer edge of the trunk. The electrode insertion depth is 20cm, and the electrodes are perpendicular to the ground at 90°. Stimulation time: 5 minutes after each application. The voltage output of the pulse generator is 15kV. The electrodes are graphite electrodes with a diameter of 5cm. The pulse width is 90ms, and the pulse interval is 0.8s. The stimulation time for each avocado tree is 1800s. The discharge surface area of ​​the electrode at the center of the trunk is approximately 1:1 to the discharge surface area of ​​the six electrodes on the circumference. After each round of pulse stimulation, the anode and cathode are reversed for the next round of pulse stimulation.

[0123] 4. Ultraviolet light source irradiation treatment: Tie a 30cm long, 60W ultraviolet lamp to the trunk of the avocado tree, in the middle of the canopy. The ultraviolet irradiation operation conditions are: irradiate for 45 minutes and then stop for 15 minutes. The irradiation time is 8 hours. The ultraviolet light source is a commercially available ultraviolet lamp wrapped with a 0.02mm thick polystyrene film. The ultraviolet treatment time point is 5 days after each pulse electric field treatment.

[0124] 5. Mechanical vibration-induced root lignification in avocado trees: A vibrator was used to operate along the drip line of the tree canopy, with 6 operating points arranged around the trunk at the 2 o'clock, 4 o'clock, 6 o'clock, 8 o'clock, 10 o'clock, and 12 o'clock positions. The vibrator head was inserted into the ground to a depth of 30 cm, with a vibration frequency of 6000 times / minute, an amplitude of 3 mm, and a vibration time of 30 seconds per operating point. The vibration operation was started 2 hours after each UV irradiation session.

[0125] 6. Avocado fertilizer nutrient management: Apply ammonium nitrate phosphate compound fertilizer: potassium sulfate: sodium silicate in a mass ratio of 2:1:1 per plant, 0.25 kg per application, once every 3 months, to prepare a 0.5% concentration of water-soluble fertilizer, and apply by drip irrigation, with the drip irrigation system arranged in a circle 10 cm inside the drip line.

[0126] Control group 3.1: Only drenching was used (compared to implementation case 3), that is, only steps 1, 2 and 6 were performed.

[0127] Control group 3.2: Only pulsed electric field stimulation was used (compared to implementation case 3), that is, only steps 1, 3 and 6 were performed.

[0128] Control group 3.3: Only ultraviolet light irradiation was used (compared to implementation case 3), that is, only steps 1, 4 and 6 were performed.

[0129] Control group 3.4: Only mechanical stimulation was used (compared to implementation case 3), i.e. only steps 1, 5 and 6 were performed.

[0130] Natural growth group: No measures were taken, steps 1-6 were not performed, and the plants grew naturally.

[0131] Two years after planting avocado seedlings using the above method, relevant indicators were tested. The testing method of Example 1 was used, which will not be elaborated here.

[0132] Table 3 Results of control treatments for Fulte avocado trees

[0133]

[0134] The comparative data from this embodiment show that the individual application of nutrient-enhancing liquid, pulsed electric field treatment, ultraviolet lamp irradiation, and mechanical stress induction has limited effect on improving the resistance to root rot and promoting root development in Forte avocado seedlings, and is lower than the combined effect of multiple treatments coupled in a specific spatiotemporal pattern. The combined treatment strategy can more effectively increase the lignin content of avocado seedling roots, reaching 35.8%, which is about 32.1% higher than the lignin content of naturally grown seedlings. The root tensile strength of the embodiment reached 56.1 MPa, which is about 47.2% higher than that of naturally grown seedlings. The root density of the embodiment was about 17.5% higher than that of naturally grown seedlings. The embodiment enhanced the resistance of avocados to root rot induced by Phytophthora camphorata. During the 75-day observation period, the embodiment was rated as very healthy, while the other control groups were infected to varying degrees. This spatiotemporal coupled treatment method significantly improves the tensile strength and root density of the root system, promotes the root lignification process, and thus enhances the plant's adaptability to abiotic stresses such as drought and salinity. At the same time, this treatment helps reduce the risk of root breakage caused by wind damage or soil displacement, and expands the range of root absorption of soil nutrients and water, thereby improving the overall growth stability and adaptability of the plant.

Claims

1. A method for increasing the lignin content in the roots of Lauraceae fruit trees, characterized by: Includes the following steps: A. Shaping: Prune the Lauraceae fruit trees appropriately; B. Application of nutrient-enhancing solution: Apply nutrient-enhancing solution to the pruned fruit trees once every 1-3 weeks, with a total of no less than 10 applications, each application using 10-25L; the nutrient-enhancing solution is an aqueous solution containing 0.05wt%-0.5wt% seaweed extract, 0.1wt%-0.5wt% wood vinegar, 0.3wt%-1.0wt% phenylalanine, 0.02wt%-0.2wt% ferulic acid, and 0.05wt%-0.1wt% coniferyl alcohol; C. Pulsed electric field treatment: Install a pulse power generator near the fruit tree. With the trunk as the center, insert 1 to 3 electrodes evenly distributed at a distance of 3 to 10 cm from the center of the trunk, and insert 3 to 6 electrodes evenly distributed around the circumference at a distance of 1 / 2 to 3 / 4 from the drip line on the outer edge of the trunk. After 5 minutes of watering, turn on the pulse power generator to stimulate the pulse electric field. D. Ultraviolet light source irradiation treatment: Tie a 40-80W ultraviolet lamp to the trunk of the fruit tree. Turn on the ultraviolet lamp to irradiate the tree on the 3rd to 7th day after the pulse electric field treatment is completed. E. Mechanical vibration induces lignification of fruit tree roots: Insert 4 to 8 vibration heads evenly distributed around the drip line of the fruit tree as working points. Turn on the vibration heads 1 to 3 hours after the ultraviolet light source irradiation begins and carry out vibration operation. F. Fruit fertilizer nutrition management: Apply fruit fertilizer to the pruned fruit trees. The fertilization frequency is once every 2 to 4 months. The fruit fertilizer applied each time is ammonium nitrate phosphate compound fertilizer: potassium sulfate: sodium silicate in a mass ratio of 1.5 to 3: 0.8 to 1.2: 0.8 to 1.

2.

2. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step A, at least one of the following must be satisfied: Lauraceae fruit trees are 1-3 year old saplings of the Lauraceae family; After pruning, the tree height is 90-200cm, with 3-5 main branches retained, the angle between the main branches is 100-150°, and the crown is open and umbrella-shaped; The pruning period is in spring before new buds sprout, when the temperature is above 15℃. Pruning should be done lightly, leaving enough leaves to maintain photosynthesis; Apply petroleum jelly to any cuts made in branches with a diameter exceeding 1.5cm to prevent bacterial invasion.

3. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step A, the Lauraceae fruit tree is the avocado genus of the Lauraceae family.

4. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step A, the Lauraceae fruit trees are the American avocado, Mexican variety, Guatemalan variety, or West Indian variety of the genus *Avocado* in the Lauraceae family.

5. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step A, the Lauraceae fruit tree is the avocado tree.

6. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step B, at least one of the following must be satisfied: The first application of nutrient-enhancing solution should be started 15–45 days after pruning; The application frequency is once every 2 to 3 weeks; The total number of applications is 20-80. Apply the solution on a sunny morning, avoiding strong sunlight. When applying the nutrient-enhancing solution, spray it evenly on the soil surface around the roots of the fruit trees and on the back of the leaves. When applying the solution, keep the soil moist but not waterlogged.

7. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step C, at least one of the following must be satisfied: Electrode insertion depth: 10–30 cm; The electrodes are graphite electrodes or titanium electrodes, with a diameter of 3–8 cm; The electrode is perpendicular to the ground at a 90° angle. The ratio of the sum of the surface areas of the electrodes at the center of the trunk to the sum of the surface areas of the electrodes on the circumference is 1 ± 0.1 : 1 ± 0.

1.

8. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step C, insert 1 to 2 electrodes evenly distributed at a distance of 3 to 10 cm from the center of the trunk, and insert 4 to 5 electrodes evenly distributed on the circumference at a distance of 1 / 2 to 3 / 4 from the drip line on the outer edge of the trunk.

9. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step C, insert one electrode at a distance of 3-10cm from the center of the trunk, and insert one electrode at each of the four points (three, six, nine, and twelve) on the circumference at a distance of 1 / 2-3 / 4 from the drip line on the outer edge of the trunk.

10. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step C, at least one of the following must be satisfied: During pulsed electric field stimulation, the output voltage of the voltage pulse generator is 5–20 kV, and the pulse width is 60–120 ms. During pulsed electric field stimulation, the pulse interval of the voltage pulse generator is 0.2–2 seconds. The duration of each pulsed electric field stimulation is 1200–2400 seconds; After each round of pulsed electric field stimulation is completed, the anode and cathode will be reversed in the next round of pulsed electric field stimulation.

11. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step D, at least one of the following must be satisfied: The length of the ultraviolet lamp is 20-40cm; Tie the ultraviolet lamp to the middle of the canopy of the fruit tree trunk; The ultraviolet lamp is an ultraviolet lamp wrapped with a polystyrene film with a thickness of 0.01 to 0.03 mm; The operating conditions for ultraviolet irradiation are as follows: irradiate for 30-60 minutes and then stop for 10-20 minutes, with a total irradiation time of 6-10 hours.

12. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step E, at least one of the following must be satisfied: The vibrating head is inserted into the ground to a depth of 20-40cm. Insert a vibrating head at each of the following points on the circumference of the drip line of the fruit tree: 2 o'clock, 4 o'clock, 6 o'clock, 8 o'clock, 10 o'clock and 12 o'clock.

13. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step E, at least one of the following must be satisfied: During vibration operation, the vibration frequency is 2000-8000 times / minute, the amplitude is 2-5mm, and the vibration time is 15-60s / operation point. During vibration operation, each vibrating head performs vibration operation sequentially, continuously without the need for interval operation time.

14. The method for increasing the lignin content in the roots of Lauraceae fruit trees according to claim 1, characterized in that: In step F, at least one of the following must be satisfied: Apply fruit fertilizer for the first time on the day of pruning or within 3 days; The total mass of ammonium nitrate phosphate compound fertilizer, potassium sulfate, and sodium silicate applied each time is 0.2–0.3 kg; When applying, prepare the fruit fertilizer into a solution with a concentration of 0.3-0.7% and apply it via drip irrigation. The drip irrigation system should be installed in a circle 5-15cm inside the drip line.

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