Apple deep-rooted cultivation method suitable for M9T337 rootstock

Abstract

The invention relates to the technical field of fruit tree cultivation, and discloses an apple deep-rooted cultivation method suitable for M9T337 rootstock, the apple deep-rooted cultivation method comprises the steps of nursery stock pretreatment, ditching and field planting, staged soil covering and chemical control management, rootstock cortex rooting is induced by combining layer-by-layer soil covering and chemical control measures, and the problems of shallow root system and poor stress resistance of the M9T337 rootstock are solved. According to the method, a complete technical chain of pretreatment, field planting, root inducing, regulation and maintenance is constructed, a continuous deep root induction environment is created through staged soil covering, and a deep root cultivation mode from passive adaptation to active induction is realized by matching with pretreatment of a composite agent to induce rooting and chemical control management to coordinate nutrient distribution. Practice shows that after M9T337 rootstock apple seedlings cultivated through the method are planted for one year, the proportion of deep root systems below 30 cm is increased to 45-50% from 15-20% of traditional cultivation, the length of main roots can reach 50-60 cm, root system distribution is more reasonable, and the deep water and fertilizer absorption capacity is remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of fruit tree cultivation technology, specifically to a deep-root cultivation method for apples suitable for M9T337 rootstock. Background Technology

[0002] The apple industry is one of the important pillars of the agricultural economy in southern Xinjiang. With the continuous optimization of the forestry and fruit industry structure and the promotion of quality and efficiency improvement, dwarfing rootstock technology has been widely promoted and applied to meet the requirements of high-density cultivation, mechanized operations, and high-quality and high-yield apple production. M9T337 rootstock, as a typical dwarfing rootstock, is widely used in modern densely planted apple orchards due to its advantages such as early fruiting, good crown control, and convenient shaping and management. However, this rootstock has weaknesses such as shallow root system, poor stress resistance, and easy lodging. Especially in the environment of water scarcity, soil salinization, and high evaporation in southern Xinjiang, its shallow root characteristics seriously restrict the stable growth and high yield of fruit trees.

[0003] Southern Xinjiang is located in one of my country's most arid regions, with a typical temperate continental climate. Annual precipitation is generally between 50-100 mm, far below the normal water requirements of fruit trees. Agricultural irrigation heavily relies on artificial water conveyance and water-saving irrigation facilities. The soil structure in this region is mostly sandy loam or saline-alkali soil, with poor water and fertilizer retention capacity, making it difficult for roots to extend deeper. Traditional shallow planting methods result in apple tree roots being concentrated within 30 cm of the soil surface, exacerbating evaporation loss and increasing the risk of wind damage and lodging, thus affecting the growth cycle, yield, and lifespan of the fruit trees.

[0004] Furthermore, the rapid warming in spring and the hot, dry summers in southern Xinjiang place higher demands on the drought resistance, heat resistance, and deep absorption capacity of fruit tree roots. In recent years, although some studies have attempted to promote the downward extension and deep fixation of rootstock roots through methods such as deep planting of large seedlings and rooting powder treatment, these methods generally suffer from problems such as complex technical operations, high costs, and poor adaptability, resulting in inconsistent effectiveness on M9T337 rootstock.

[0005] In conclusion, there is an urgent need for a deep-rooted cultivation method that is adapted to the arid, saline-alkali, and complex irrigation conditions of southern Xinjiang, and is structurally sound, easy to operate, and yields stable results, taking into account the shallow root system and weak stress resistance of the M9T337 rootstock. This technology should be developed by combining the physiological characteristics of the M9T337 rootstock, soil structure conditions, and water management principles to form a new, scalable cultivation technique to improve the stability, stress resistance, and overall orchard productivity of apple trees. Summary of the Invention

[0006] The purpose of this invention is to provide a deep-rooted cultivation method for apples using M9T337 rootstock. Addressing the inherent shallow root development and weak stress resistance of M9T337 rootstock, as well as the shortcomings of existing cultivation methods in the unique environment of southern Xinjiang—namely, poor deep-rooting effects and lack of systematic implementation—this invention provides a deep-rooted cultivation method for apples using M9T337 rootstock. By constructing a complete technical system encompassing "seedling pretreatment - trenching and planting - phased soil covering and root induction - chemical control management - precision irrigation," this method directionally induces root growth in the rootstock bark and extends it into deeper soil layers. This enhances the root system's ability to absorb water and fertilizer from deeper layers, improves the fruit tree's drought resistance, lodging resistance, and salt tolerance, extends its economic lifespan, and achieves high-quality, high-yield, and sustainable development of M9T337 rootstock apple orchards in southern Xinjiang.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for deep-rooted cultivation of apples suitable for M9T337 rootstock, including seedling pretreatment, trenching and planting, staged soil covering and chemical control management steps. By layering soil covering combined with chemical control measures, the rootstock bark is induced to develop roots, solving the problems of shallow root system and poor stress resistance of M9T337 rootstock. It is suitable for the arid and rainless environment of southern Xinjiang with poor soil water retention, promotes deep root development, and improves the drought resistance, lodging resistance and yield stability of fruit trees.

[0008] Preferably, in the seedling pretreatment step, healthy M9T337 rootstock seedlings with a rootstock segment length of 50-55cm are selected and soaked in a compound aqueous solution containing 0.1‰ rooting powder and 0.2‰ carbendazim for 24-36 hours. After the seedlings have fully absorbed water and completed pathogen prevention treatment, the damaged roots are cut off, leaving only 20-25 cm of healthy main roots and capillary roots. This lays the foundation for subsequent directional deep rooting and rapid rooting, which is different from the traditional seedling pretreatment method that only involves simple pruning or single-agent treatment.

[0009] Preferably, the trenching and planting step is carried out in mid-April each year. A planting trench with a depth of 50cm and a width of 30-40cm is dug in the planting plot. The bottom of the trench is kept in its original soil state without adding any base fertilizer or covering material. The pre-treated seedlings are vertically planted in the trench, allowing the roots to spread out and hang down naturally. The initial soil covering height is controlled at 25-30cm and gently compacted, ensuring that the upper 20-25cm of the rootstock is exposed on the ground surface. This leaves specific space for subsequent staged soil covering to induce bark rooting, breaking through the traditional shallow planting or one-time deep planting cultivation mode.

[0010] Preferably, the first layer of soil covering in the phased covering is carried out in mid-June, with a 10cm thick layer of soil evenly covering the base of the seedling. This soil is mature soil that has been turned over and sun-dried, and weeds and pests have been removed. An appropriate amount of clean fine sand is mixed in the area near the trunk to optimize the local soil structure, improve aeration and drainage, and meet the physiological characteristics of enhanced rooting ability of the rootstock bark after the temperature rises at this time, so as to achieve targeted root induction.

[0011] Preferably, the second layer of soil covering in the phased soil covering is carried out at the end of July. Another 10cm layer of mature soil is added around the trunk, and an appropriate amount of clean fine sand with a particle size of 1-3mm is mixed in near the trunk so that the cumulative depth of the two layers of soil covering reaches 45-50cm. This ensures that the M9T337 rootstock segment is basically buried in the soil and the grafting interface is above the ground. This vertical layer covering creates a continuous root-inducing environment, which is different from the existing one-time soil covering or soil covering without a specific time point.

[0012] Preferably, the chemical control management step is carried out promptly after each soil covering. Gibberellin inhibitors such as paclobutrazol, chlormequat chloride, or uniconazole are selected as plant growth regulators. The concentration is precisely adjusted according to the tree vigor and sprayed onto the above-ground new shoots. By inhibiting the excessive growth of new shoots, the nutrient consumption of the above-ground parts is reduced, the transpiration water consumption of the plant is reduced, the growth coordination between the above-ground and underground parts is improved, the nutrients are guided to be concentrated and supplied to the root system, and the formation and deep extension of rooting points in the rootstock bark are promoted. This overcomes the technical defects of traditional cultivation that lack the synergistic cooperation between soil covering and chemical control.

[0013] Preferably, in the later management after the second covering is completed, a combination of furrow irrigation and drip irrigation is adopted, with the irrigation interval controlled at 10-15 days. This avoids the adverse situation of the surface being moist while the deep soil is dry, ensuring that the deep roots can continuously obtain water and nutrients. This is suitable for the arid and rain-scarce environment of southern Xinjiang, where agricultural irrigation relies on artificial water delivery, and is different from the traditional single irrigation mode.

[0014] Preferably, the topsoil used for the staged covering is strictly screened and must have good water retention, air permeability and loose structure. Fine sand is added in both covering processes to create a suitable physical and chemical environment for rooting of the rootstock bark through the optimized configuration of soil composition. This solves the problem of poor water and fertilizer retention capacity and difficulty in deep root expansion in sandy loam or saline-alkali soils in southern Xinjiang.

[0015] Preferably, during the entire cultivation process, the seedling pretreatment stage uses compound agents to soak the seedlings to achieve the dual effects of root induction and disease prevention. After planting, a layered root induction system is constructed by covering the seedlings with soil at specific time points. Combined with chemical control management after soil covering and precise irrigation in the later stage, a complete technical chain of "pretreatment-planting-root induction-regulation-maintenance" is formed, realizing the systematic optimization of deep root cultivation of M9T337 rootstock, which is different from the existing fragmented and uncoordinated cultivation techniques.

[0016] Preferably, this method is specifically adapted to orchards in the arid and rain-scarce region of southern Xinjiang, where soil water retention is poor, evaporation is intense, and soil salinization is a problem. By promoting the formation of a deep and well-developed root system in the M9T337 rootstock, it significantly enhances the fruit trees' ability to absorb water and fertilizer from deep soil, improves the plants' drought resistance and wind lodging resistance, extends the economic lifespan of the fruit trees, and solves the problem of poor adaptability and unstable effects of traditional cultivation techniques in the special environment of southern Xinjiang.

[0017] This invention provides a method for deep-rooted cultivation of apples using M9T337 rootstock. It has the following beneficial effects: 1. This invention constructs a complete technical chain of "pretreatment-planting-root induction-regulation-maintenance," creating a continuous deep-root induction environment through phased soil covering. Combined with compound agent pretreatment to induce root growth and chemical control management to coordinate nutrient distribution, it achieves a deep-root cultivation model that transitions from "passive adaptation" to "active induction." Practice shows that M9T337 rootstock apple seedlings cultivated using this method, one year after planting, have a higher proportion of roots deeper than 30cm from 15-20% in traditional cultivation to 45-50%, with taproot length reaching 50-60cm. The root distribution is more rational, and the deep water and fertilizer absorption capacity is significantly enhanced.

[0018] 2. The deep-rooted system of this invention can absorb water and nutrients from deep soil, significantly improving the drought resistance of fruit trees. During the dry season in southern Xinjiang, normal growth can be maintained without frequent irrigation, reducing irrigation water consumption by 30-40% compared to traditional cultivation. At the same time, the support of the deep root system is enhanced, increasing the lodging resistance of fruit trees by more than 60%, effectively resisting the impact of windy weather in southern Xinjiang in spring. In addition, the addition of fine sand during the staged covering of soil optimizes the soil structure, reduces soil bulk density, and improves aeration, effectively alleviating the salinization damage in some plots of southern Xinjiang, and significantly improving the root growth environment.

[0019] 3. This invention's chemical control management suppresses excessive shoot growth, avoids ineffective nutrient consumption, and guides nutrients to be concentrated on the roots and fruits, resulting in more robust tree growth, a more reasonable leaf area index, and improved photosynthetic efficiency. Fruit trees cultivated using this method do not suffer from precocity; they can bear fruit in the second year after planting and enter their peak fruiting period in the third year. Fruit yield is increased by 15-20% compared to traditional cultivation, and the soluble solids content of the fruit is increased by 1-2 percentage points, resulting in superior quality. Simultaneously, the tree's growth is stable, the decline period is delayed by 5-8 years, and its economic lifespan is significantly extended.

[0020] 4. All technical measures of this invention are designed based on the actual planting conditions in southern Xinjiang. They do not require complex equipment or high costs. The phased soil covering, chemical control spraying, and precision irrigation are simple and easy to implement, making them easy to promote and apply on a large scale. The materials used (rooting powder, carbendazim, plant growth regulators, fine sand, etc.) are easy to obtain and the cost is controllable, making them suitable for fruit farmers in southern Xinjiang.

[0021] 5. This invention reduces irrigation water consumption, which is in line with the current situation of water scarcity in southern Xinjiang and realizes water-saving cultivation; deep-root cultivation improves the utilization rate of soil organic matter, reduces surface soil erosion, and is conducive to improving the ecological environment of orchards; the fruit trees are more resistant to adverse conditions, reducing the use of pesticides and fertilizers, and realizing green and sustainable cultivation. Attached Figure Description

[0022] Figure 1 This is a flowchart of the method steps of the present invention; Figure 2 This is a flowchart illustrating the phased soil covering requirements of the present invention. Figure 3 This is a flowchart illustrating the regional adaptation and effect logic of the present invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0025] Example 1 (Application in orchards on flat land in arid areas of southern Xinjiang) The deep-root cultivation method for apples using M9T337 rootstock provided by this invention is specifically applied in apple orchards on flat land in Aksu region of southern Xinjiang as follows: Seedling pretreatment: Select 100 robust M9T337 rootstock Fuji apple seedlings with a rootstock section length of 52cm and a ground diameter of 0.8cm. Remove the nutrient soil covering the roots and soak the roots in a compound aqueous solution containing 0.1‰ rooting powder and 0.2‰ carbendazim for 30 hours, maintaining the aqueous solution temperature at 22℃. After soaking, use sharp scissors to cut off any damaged or rotten roots, retaining 22cm of healthy main roots and attached fine roots, and place them in a cool, shady place for later use.

[0026] Trenching and Planting: Dig planting trenches at a spacing of 3m x 4m in the planting area, 50cm deep and 35cm wide. After clearing stones from the bottom of the trench, keep the original soil intact. Vertically plant the pre-treated seedlings in the trench, allowing the roots to spread out naturally and droop, contacting the original soil at the bottom of the trench. Initially cover with soil to a height of 28cm, gently compacting it with your feet, ensuring that the top 24cm of the rootstock is exposed above the ground, and the grafting point is 8cm above the ground.

[0027] First soil covering: Perform the first soil covering. Select mature soil that has been turned over and sun-dried for 15 days and has been cleared of weeds and pests. Cover the base of the seedling evenly with a 10cm thick layer. Mix clean fine sand into the soil within 10cm of the trunk (soil to fine sand volume ratio 3:1). After covering, gently compact the soil to ensure close contact between the soil and the bark of the rootstock.

[0028] Chemical control management (first time): The day after the first soil covering, use a 180mg / L paclobutrazol solution and spray it evenly on the above-ground new shoots of the seedlings using a manual sprayer, focusing on the tips of the new shoots, and ensuring that the leaves are evenly coated with the medicine on both sides, avoiding missed spraying and over-spraying.

[0029] Second covering: Perform the second covering. Continue to use qualified mature soil and cover it with a 10cm layer around the trunk. Similarly, mix clean fine sand with a particle size of 1-3mm (soil to fine sand volume ratio 3:1) within a 10cm range from the trunk. The total depth of the two coverings is 48cm, and the grafting point is still 6cm above the ground.

[0030] Chemical control management (second time): The day after the second covering with soil, use 100mg / L paclobutrazol solution to spray the new shoots for the second time, with the spraying amount being the same as the first time.

[0031] Post-treatment management: After the second layer of soil is applied, a combination of furrow irrigation and drip irrigation should be used. Furrow irrigation should be applied every 15 days, with a volume of 50L per tree each time to moisten the deeper soil layers; drip irrigation should be applied every 10 days, with a volume of 15L per tree each time to replenish surface moisture. Regularly remove weeds from the orchard to prevent them from competing with the fruit trees for water and nutrients.

[0032] Example 2 (Application in slightly saline-alkali land in southern Xinjiang) The specific application of this invention in a mildly saline-alkali apple orchard in Kashgar region of southern Xinjiang is as follows: Seedling pretreatment: Eighty Gala apple seedlings with M9T337 rootstock (55cm in length and 0.9cm in diameter at ground level) were selected. The roots were soaked in a compound aqueous solution containing 0.1‰ rooting powder and 0.2‰ carbendazim for 36 hours at a temperature of 23℃. After soaking, damaged roots were removed, leaving 25cm of healthy main roots. The seedlings were then kept moist in a cool, shaded place for later use.

[0033] Trenching and planting: Dig planting trenches at a spacing of 3m×3.5m, with a trench depth of 50cm and a width of 40cm. After the original soil at the bottom of the trench has been dried for 3 days, plant the seedlings. Cover with 30cm of soil initially, compact it, and leave the top 25cm of the rootstock exposed. The grafting point should be 10cm above the ground surface.

[0034] First covering with soil: Cover with 10cm of topsoil (add 5% well-rotted sheep manure to improve the soil when turning and drying), and mix fine sand within 15cm around the tree trunk (soil to fine sand volume ratio 2.5:1) to enhance soil permeability and alleviate salinity damage.

[0035] Chemical control management (first time): Spray the new shoots with a 70mg / L mepiquat chloride solution.

[0036] Second covering: Cover with 10cm of improved topsoil, and mix fine sand around the trunk within 15cm, for a total covering depth of 50cm.

[0037] Chemical control management (second time): Spray the new shoots with a 40mg / L mepiquat chloride solution.

[0038] Post-treatment management: Use a combination of furrow irrigation and drip irrigation. Furrow irrigation should be done every 12 days, and drip irrigation every 8 days. Add an appropriate amount of desulfurized gypsum to improve salinity and alkalinity during irrigation. Regularly monitor soil salinity to ensure a suitable environment for root growth.

[0039] Working principle The core working principle of this invention is based on the physiological characteristics of the M9T337 rootstock and the environmental characteristics of southern Xinjiang. Through a synergistic mechanism of "environmental adaptation - physiological induction - growth regulation - maintenance and protection," it directionally induces the rootstock to form a deep root system, specifically through the synergistic effect of four key links: I. Rooting Induction and Disease Prevention Mechanisms of Seedling Pretreatment The bark of M9T337 rootstock possesses potential for root development. The core of seedling pretreatment is to activate this potential and ensure root health. In the compound aqueous solution, rooting powder (such as naphthaleneacetic acid), acting as a plant growth regulator, can penetrate root epidermal cells, promote cell division and differentiation, and induce the formation of adventitious root primordia, laying the foundation for subsequent deep root growth. Carbendazim, as a broad-spectrum fungicide, can form a protective film on the root surface, killing attached pathogens and preventing soil pathogens from infecting the roots after planting, reducing root diseases and ensuring normal root growth. Simultaneously, pruning damaged roots reduces ineffective nutrient consumption, allowing healthy roots to concentrate on absorbing water and nutrients, thus improving rooting efficiency.

[0040] II. Deep Root Orientation Induction Mechanism of Staged Soil Covering The core technology of this invention for achieving deep rooting is phased soil covering. Its essence is to guide the rooting bark rooting points to gradually form from the surface to the deep layer by "gradually burying soil and inducing roots in layers", and finally build a deep root system.

[0041] Timing should be tailored to physiological characteristics: The first covering should be done in mid-June, when the temperature in southern Xinjiang rises and the soil temperature stabilizes above 25℃. The new shoots of the M9T337 rootstock enter a vigorous growth period, photosynthetic products accumulate more, the activity of rootstock cortex cells is enhanced, and the rooting capacity reaches its peak. Covering the rootstock at this time can stimulate the cortex to form a large number of rooting points. The second covering should be done at the end of July, when the roots in the surface cortex formed in the first induction have begun to grow. Covering the rootstock at this time can further stimulate the formation of new rooting points in the middle and lower cortex, guiding the roots to extend deeper and avoiding the roots from being concentrated on the surface.

[0042] Soil optimization to meet rooting needs: The topsoil used for staged covering is turned over and sun-dried to remove weeds and pests, and mixed with fine sand, which significantly improves soil aeration and drainage, and reduces soil bulk density. M9T337 rootstock bark rooting requires high soil aeration; a loose soil structure ensures normal root respiration and avoids rooting failure due to oxygen deficiency. At the same time, the addition of fine sand improves soil water retention, maintaining suitable humidity around the roots in the arid environment of southern Xinjiang, providing the necessary conditions for rooting.

[0043] Vertical covering creates a continuous root-inducing environment: The cumulative depth of the two coverings reaches 45-50cm, so that the M9T337 rootstock segment is basically buried in the soil, forming a vertical "soil gradient". The temperature, humidity, aeration and other environmental conditions of each soil layer are different, which can stimulate the bark of the rootstock at different heights to form rooting points. During the growth process, these roots will naturally extend into the deeper soil to obtain more stable water and nutrients, eventually forming a deep and well-developed root system.

[0044] III. Growth Coordination Mechanism of Chemical Control Management The M9T337 rootstock exhibits apical dominance in nutrient distribution. During vigorous shoot growth, a large amount of nutrients is transported to the above-ground parts, leading to insufficient nutrient supply to the underground root system and inhibiting deep root growth. The core of chemical control management is to break apical dominance by spraying gibberellin inhibitors, thereby coordinating the growth relationship between the above-ground and underground parts.

[0045] Regulators such as paclobutrazol, mepiquat chloride, and uniconazole can inhibit the growth of apical meristems in new shoots, reduce the growth rate of new shoots, and decrease nutrient consumption in the above-ground parts. Simultaneously, these regulators can promote the translocation of photosynthetic products to the underground root system, concentrating nutrients at the rooting points, accelerating root cell division and growth, and promoting the formation and extension of cortical roots. Furthermore, inhibiting new shoot growth reduces the plant's transpiration area and water consumption through transpiration. In the arid environment of southern Xinjiang, this can reduce the impact of water stress on root growth and further enhance the deep root induction effect.

[0046] IV. Maintenance and Support Mechanism for Precision Irrigation The ultimate realization of deep-rooted cultivation requires precise water supply as a guarantee. In southern Xinjiang, evaporation is intense, and traditional single-irrigation methods easily lead to rapid water loss, failing to meet the needs of deep root growth. This invention employs a combined furrow irrigation and drip irrigation system. Furrow irrigation delivers water to the deeper soil layers, moistening the top 40-50cm to meet the water requirements of deep roots and guide them to extend deeper. Drip irrigation replenishes surface soil moisture, preventing physiological water shortages caused by surface drought, while maintaining normal growth of surface roots, forming a root water supply system that prioritizes deep roots and supplements surface roots. The 10-15 day irrigation interval not only conforms to the soil moisture evaporation patterns in southern Xinjiang but also avoids excessive soil salinization caused by over-irrigation, providing a stable water environment for deep root growth.

[0047] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0048] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for deep-rooted cultivation of apples suitable for M9T337 rootstock, characterized in that, The process includes seedling pretreatment, trenching and planting, phased soil covering, and chemical control management. The method involves layering soil and using chemical control measures to induce root growth in the rootstock bark. Specifically, the steps include: Step 1: Seedling Pretreatment. Select healthy M9T337 rootstock seedlings with a rootstock section length of 50-55cm. Soak them in a solution containing 0.1% rooting powder and 0.2% carbendazim for 24-36 hours. Stir the solution every 8 hours during soaking to ensure that all parts of the seedling root system are fully in contact with the solution. After the seedlings have fully absorbed water and completed pathogen prevention treatment, prune the damaged roots, leaving only 20-25cm of healthy main roots and capillary roots. After pruning the damaged roots, spray the root surface with a 0.2% carbendazim solution to disinfect the pruning wounds and prevent infection. This lays the foundation for subsequent directional deep rooting and rapid root development. Step 2, Trenching and Planting, is carried out in mid-April each year. A planting trench with a depth of 50cm and a width of 30-40cm is dug in the planting area. The bottom of the trench is kept in its original soil state without adding any base fertilizer or covering material. The pre-treated seedlings are vertically planted in the trench, allowing the roots to spread out and hang down naturally. The initial soil covering height is controlled at 25-30cm and gently compacted, ensuring that the top 20-25cm of the rootstock is exposed above the ground, reserving specific space for subsequent staged soil covering to induce bark rooting. Step 3: The first layer of soil covering in stages is carried out in mid-June. Before covering the soil, spray 200ppm rooting powder within 20cm of the base of the main trunk exposed above the soil surface. Evenly cover the base of the seedling with 10cm of soil. This soil is mature soil that has been turned over and sun-dried, and weeds and pests have been removed. In the area near the trunk, mix in an appropriate amount of clean fine sand (or sawdust). The soil covering around the main trunk is 10-15cm higher than the surrounding area. By optimizing the local soil structure, the aeration and drainage are improved, which is in line with the physiological characteristics of the rootstock bark rooting ability enhanced after the temperature rises at this time, so as to achieve targeted root induction. Step 4: The second layer of soil covering in stages will be carried out at the end of July. Before covering the soil, spray 200ppm rooting powder within 20cm of the base of the trunk exposed above the soil surface. Continue to add 10cm of mature soil around the trunk. Similarly, mix an appropriate amount of clean fine sand (or sawdust) with a particle size of 1-3mm near the trunk. The soil covering height around the trunk should be 10-15cm higher than the surrounding area. After the two layers of soil covering, the rootstock burial depth will reach a total of 45-50cm, ensuring that the M9T337 rootstock segment is basically buried in the soil and the grafting interface is above the ground. A continuous root-inducing environment is created through vertical layer covering. Step 5, Chemical Control Management: This step is carried out promptly after each soil covering. Use gibberellin inhibitors such as paclobutrazol, chlormequat chloride, uniconazole, or calcium cyclohexane as plant growth regulators. Precisely adjust the concentration according to the tree vigor and the instructions before spraying it onto the above-ground new shoots. By inhibiting the excessive growth of new shoots, it reduces the nutrient consumption of the above-ground parts, reduces the transpiration and water consumption of the plant, improves the coordination of growth between the above-ground and underground parts, guides the concentrated supply of nutrients to the root system, and promotes the formation and deep extension of rooting points in the rootstock bark.

2. The method for deep-rooted apple cultivation using M9T337 rootstock as described in claim 1, characterized in that, In the later management after the second covering is completed, a combination of furrow irrigation and drip irrigation is adopted, with the irrigation interval controlled at 10-15 days. If the soil moisture content around the main trunk is less than 60%, furrow irrigation or drip irrigation can be used to supplement water appropriately to avoid the adverse situation of wet surface and dry deep soil, ensuring that the deep roots can continuously obtain water and nutrients, which is suitable for the arid and rain-scarce environment of southern Xinjiang where agricultural irrigation relies on artificial water delivery.

3. The method for deep-rooted apple cultivation using M9T337 rootstock as described in claim 1, characterized in that, The topsoil used for the phased covering is strictly screened and must have good water retention, air permeability and loose structure. Fine sand is added in both covering processes to create a suitable physical and chemical environment for rooting of the rootstock bark through optimized soil composition.

4. The method for deep-rooted apple cultivation using M9T337 rootstock as described in claim 1, characterized in that, Throughout the cultivation process, the seedlings are soaked in a compound agent during the pretreatment stage to achieve the dual effects of root induction and disease prevention. After planting, a layered root-inducing system is constructed by covering the seedlings with soil at specific time points. Combined with chemical control management after soil covering and precise irrigation in the later stage, a complete technical chain of "pretreatment-planting-root induction-regulation-maintenance" is formed, realizing the systematic optimization of deep-rooted cultivation of M9T337 rootstock.

5. The method for deep-rooted apple cultivation using M9T337 rootstock as described in claim 1, characterized in that, This method is specifically designed for orchards in the arid and rain-scarce southern Xinjiang region, where soil water retention is poor, evaporation is high, and soil salinization is a problem. By promoting the formation of a deep and well-developed root system in M9T337 rootstock, it significantly enhances the fruit trees' ability to absorb water and fertilizer from deep soil layers, improves the plants' resistance to drought, drought, secondary soil salinization, and wind lodging, reduces the impact of low winter temperatures on the root system and secondary salinization in the orchard, ensures the healthy growth and safe overwintering of fruit trees, and extends the economic lifespan of the fruit trees.

6. The method for deep-rooted apple cultivation using M9T337 rootstock according to claim 1, characterized in that, In the seedling pretreatment step, the concentrations of rooting powder and carbendazim solutions are precisely controlled, with the rooting powder concentration being 0.1% and the carbendazim concentration being 0.2%. The soaking time is strictly controlled between 24 and 36 hours. The stirring operation ensures that the solution is in full contact with the roots. The wound disinfection process after pruning works synergistically with the soaking treatment to comprehensively improve the health and rooting activity of the seedling roots.

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