Seed breeding method for cotoneaster setonii seedlings

Abstract

The invention discloses a seed breeding method for seedlings of cotoneaster cotoneaster, and relates to the technical field of agricultural planting. Comprising the following steps: a low-temperature stratification stage: digging a stratification pit in a shady and ventilated field at the end of autumn of the first year, laying a coarse grain matrix layer with the thickness of more than or equal to 20cm at the bottom of the pit, mixing ripe cotoneaster cotoneaster seeds subjected to water immersion treatment with a mineral matrix with the particle size of 0.1-5mm according to a preset proportion, and filling the mixture into a ventilated container for oscillation homogenization treatment. The method comprises the three stages of low-temperature lamination, greenhouse sowing and germination after overwintering, it is ensured that seeds can successfully germinate and finally grow into healthy nursery stocks through a fine management means, firstly, in the last stage of autumn, a coarse grain substrate layer is laid in a shady and ventilated lamination pit, mixing the seeds subjected to water immersion treatment with a mineral matrix, loading the mixture into a breathable container, performing oscillation homogenization treatment, burying the mixture above a matrix layer, covering the matrix to ensure that the seeds are isolated from air, and reserving a space between the seeds and the matrix to promote water exchange;

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural planting, and particularly to a method for seed breeding of Cotoneaster seedlings. Background Art

[0002] Cotoneaster is a deciduous shrub of the genus Cotoneaster in the Rosaceae family. It can reach up to 4 meters in height, purplish when young, with leaves ovate or broadly ovate, apex pointed or obtuse, base broadly cuneate or rounded; bracts linear, calyx often glabrous, calyx tube campanulate; petals spreading, nearly round, with white pubescence at the base inside, stamens slightly shorter than petals, styles shorter than stamens, ovary apex with pubescence; fruit nearly spherical or obovoid, red when mature; flowering period is from May to June; fruiting period is from August to September.

[0003] In the field of seed breeding technology, how to improve the survival rate of seedlings and control the improvement of the living environment is one of the core technical challenges. The traditional methods for breeding Cotoneaster seedlings are often limited by natural conditions. For example, insufficient regulation of temperature and humidity leads to low germination rates and slow growth of seedlings. Especially in the northern regions, due to low winter temperatures and frozen soil, conventional open-field sowing methods are difficult to ensure the germination of seeds and the healthy growth of seedlings. These problems not only affect the yield of seedlings but also increase the breeding cost. According to the traditional conventional forest seedling raising method for Cotoneaster seedlings, the seeds do not germinate in the second year. Even if methods such as soaking seeds in warm water, stratification, scarification, and germination in a cold frame are used, the seeds still do not germinate in the second year. If the low-temperature stratification time of the seeds is extended to two years, the seeds still do not germinate. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for seed breeding of Cotoneaster seedlings to solve the problems raised in the above background art.

[0005] To achieve the above purpose, the present invention provides the following technical solution: A method for seed breeding of Cotoneaster seedlings, comprising the following steps:

[0006] Low-temperature stratification stage: At the end of autumn in the first year, dig a stratification pit in a shaded and ventilated site, and lay a coarse-grained substrate layer with a thickness ≥ 20 cm at the bottom of the pit;

[0007] After the mature seeds of Cotoneaster are soaked in water, they are mixed with a mineral substrate with a particle size of 0.1 - 5 mm in a predetermined proportion, filled into a breathable container for oscillating homogenization treatment, buried above the substrate layer, and then covered with substrate again until the distance between the top of the seed container and the ground surface is ≥ 25 cm, and then hydraulic sedimentation and substrate compensation filling are carried out;

[0008] Greenhouse sowing stage: In the spring of the second year, sow the stratified seeds in a greenhouse seedbed, set the sowing depth to 5 - 15 cm, and construct a covering system of heterogeneous substrates. After sowing, implement a gradient irrigation control strategy to maintain the humidity of the seed layer at a preset threshold;

[0009] During the overwintering germination stage, based on the real-time saturated light treatment of the greenhouse seedbed during the critical period of outdoor soil freezing, the continuous air exchange mode of the greenhouse ventilation system is synchronously started until the germination of the seedling population is completed in the spring of the third year.

[0010] As a specific solution of the technical solution of this application, the geometric parameters of the stratification pit in the low-temperature stratification stage satisfy the aspect ratio ≤ 1.5, the depth is 0.8 - 1.2 m, the coarse-grained substrate layer is composed of river sand with a particle size of 0.5 - 3 mm, and the laying thickness is 25 - 35 cm.

[0011] As a specific solution of the technical solution of this application, the mixing volume ratio of seeds to mineral substrate in the low-temperature stratification stage is 1:2 - 1:4, the oscillation treatment uses a mechanical oscillation device, the oscillation intensity is 20 - 50 Hz, and the treatment time is 5 - 10 minutes.

[0012] As a specific solution of the technical solution of this application, the heterogeneous substrate covering system in the greenhouse sowing stage includes a composite structure of a bottom high-permeability substrate and a top water-retaining substrate, where the thickness of the bottom substrate is 20 - 25 cm, the thickness of the top substrate is 2 cm - 5 cm, and the sand particle content of the bottom substrate is ≥ 40%.

[0013] As a specific solution of the technical solution of this application, the gradient irrigation control strategy in the greenhouse sowing stage includes:

[0014] The first irrigation makes the soil moisture content reach 80% - 100% of the field capacity;

[0015] Subsequent irrigations are real-time regulated based on the feedback data of the soil moisture sensor to maintain the moisture content of the seed layer in the range of 55% - 75%.

[0016] As a specific solution of the technical solution of this application, the continuous air exchange mode in the overwintering germination stage is achieved by regulating the opening degree of the greenhouse ventilation openings, so that the daily average temperature fluctuation range in the greenhouse in winter is -8°C to +10°C, and the air relative humidity ≤ 70%.

[0017] As a specific solution of the technical solution of this application, the water application amount of saturated irrigation in the overwintering germination stage is 250 - 400 m³ / hm², and it is implemented in two times: the first irrigation is completed within 7 days before soil freezing, and the secondary supplementary irrigation is implemented within 15 days after freezing, and the supplementary irrigation amount is 15% - 35% of the first time.

[0018] As a specific solution of the technical solution of this application, the breathable container is a woven bag.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The seed propagation method for Cotoneaster seedlings includes three stages: low-temperature stratification, greenhouse sowing, and overwintering germination. Through delicate management measures, it ensures that the seeds can germinate smoothly and finally grow into healthy seedlings. First, at the end of autumn, a layer of coarse substrate is laid in a shaded and ventilated stratification pit. Then, the seeds treated by water immersion are mixed with a mineral substrate, filled into a breathable container, and subjected to shaking homogenization treatment. After that, they are buried above the substrate layer, and the substrate is covered to isolate the seeds from the air, but there is space between the seeds and the substrate to promote water exchange. In the subsequent greenhouse sowing stage, the treated seeds are sown on a greenhouse seedbed covered with multiple heterogeneous substrates, an appropriate sowing depth is set, and a gradient irrigation strategy is adopted to control the soil water content to maintain at a preset threshold to promote seed germination. Finally, in the overwintering germination stage, the temperature in the greenhouse is maintained at -8°C to +10°C and the relative humidity ≤ 70% by regulating the continuous air exchange in the greenhouse, and saturated irrigation and substrate compensation are carried out to ensure that the seeds can survive the winter safely and germinate into seedlings. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic flow chart of the seed propagation method for Cotoneaster seedlings of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0023] It should be noted that in the description of the present invention, the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention.

[0024] In addition, it should be understood that for the convenience of description, the dimensions of the various components shown in the accompanying drawings are not drawn in actual proportional relationships. For example, the thickness or width of some layers may be exaggerated relative to other layers.

[0025] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined or described in one drawing, it will not be necessary to further specifically discuss and describe it in the description of subsequent drawings.

[0026] As Figure 1 shown, the present invention provides a technical solution: a method for seed breeding of Cotoneaster seedlings, comprising the following steps:

[0027] Low-temperature stratification stage: At the end of the first autumn, dig a stratification pit in a shaded and ventilated area, and lay a coarse-grained substrate layer with a thickness ≥ 20 cm at the bottom of the pit;

[0028] After the mature seeds of Cotoneaster are soaked in water, they are mixed with a mineral substrate with a particle size of 0.1 - 5 mm in a predetermined ratio, filled into a breathable container for oscillating homogenization treatment, buried above the substrate layer, and then covered with substrate again until the distance between the top of the seed container and the ground surface is ≥ 25 cm. Subsequently, hydraulic sedimentation and substrate compensation filling are carried out;

[0029] Greenhouse sowing stage: In the spring of the second year, sow the stratified seeds in the greenhouse seedbed, set the sowing depth to 5 - 15 cm, and construct a covering system composed of multiple layers of heterogeneous substrates. After sowing, implement a gradient irrigation control strategy to maintain the humidity of the seed layer at a preset threshold;

[0030] Post-winter germination stage: Based on the critical period of outdoor soil freezing, perform real-time saturated light treatment on the greenhouse seedbed, and synchronously start the continuous air exchange mode of the greenhouse ventilation system until the germination of the seedling population is completed in the spring of the third year. In the low-temperature stratification stage, the geometric parameters of the stratification pit satisfy a length-width ratio ≤ 1.5, a depth of 0.8 - 1.2 m, and the coarse-grained substrate layer is composed of river sand with a particle size of 0.5 - 3 mm, and the laying thickness is 25 - 35 cm.

[0031] In the low-temperature stratification stage, the mixing volume ratio of seeds to the mineral substrate is 1:2 - 1:4. The oscillation treatment uses a mechanical oscillation device, with an oscillation intensity of 20 - 50 Hz and a treatment time of 5 - 10 minutes.

[0032] In the greenhouse sowing stage, the multi-layer heterogeneous substrate covering system includes a composite structure of a bottom high-permeability substrate and a top water-retaining substrate. Among them, the thickness of the bottom substrate is 20 - 25 cm, the thickness of the top substrate is 2 cm - 5 cm, and the sand content of the bottom substrate is ≥ 40%.

[0033] In the greenhouse sowing stage, the gradient irrigation control strategy includes:

[0034] The first irrigation makes the soil moisture content reach 80% - 100% of the field capacity;

[0035] Subsequent irrigations are regulated in real time based on the feedback data of the soil moisture sensor to maintain the moisture content of the seed layer in the range of 55% - 75%.

[0036] In the post-winter germination stage, the continuous air exchange mode is achieved by regulating the opening degree of the greenhouse ventilation opening, so that the daily average temperature fluctuation range in the greenhouse in winter is -8°C to +10°C, and the relative air humidity ≤ 70%.

[0037] During the overwintering and budding stage, the water application amount for saturated irrigation is 250 - 400 m³ / hm², and it is implemented in two times: the first irrigation is completed within 7 days before the soil freezes, and the secondary supplementary irrigation is implemented within 15 days after freezing, and the supplementary irrigation amount is 15% - 35% of the first time.

[0038] The breathable container is a woven bag.

[0039] It should be clear that in the embodiments of the present application, at the end of autumn in the first year, a shady and well-ventilated site is selected to ensure that the seeds are in a suitable low-temperature environment during stratification, avoiding premature germination or heat damage of the seeds caused by high temperature. At the same time, good ventilation conditions are conducive to the normal respiration of the seeds, preventing the seeds from rotting due to lack of oxygen. The size of the stratification pit is determined according to the planned amount of seeds for stratification. Generally speaking, the length and width of the stratification pit can be flexibly set according to the actual site and the amount of seeds, but the depth should be appropriate, ensuring that the seeds can receive sufficient low-temperature treatment and facilitating subsequent management and operation. Assuming the planned volume of seeds for stratification is V, considering the expansion coefficient after the seeds are mixed with the substrate and the thickness of the coarse-grained substrate layer and the covering substrate to be laid, the volume of the stratification pit should not be less than V*(1 + expansion coefficient) / (filling rate of the seed and substrate mixture in the pit). For example, if it is planned to stratify 1 cubic meter of seeds, the expansion coefficient after the seeds are mixed with the substrate is 0.2, and the filling rate of the mixture in the pit is 0.8, then the volume of the stratification pit should not be less than 1*(1 + 0.2) / 0.8 = 1.5 cubic meters. It should also be clear that a coarse-grained substrate layer with a thickness of ≥20 cm is laid at the bottom of the stratification pit. The coarse-grained substrate layer can be made of materials such as coarse sand and gravel, and the particle diameter should be between 5-20 mm. When laying, the surface of the substrate layer should be kept flat and filled densely to provide good drainage and air permeability, preventing waterlogging from causing seed rot and facilitating gas exchange of the seeds during stratification. When processing and burying the seeds, the collected mature Cotoneaster seeds are put into clean water and soaked for more than 72 hours, with the water temperature maintained at 15-20 degrees Celsius. The water is changed every 12 hours during the soaking process to remove impurities and some pathogens on the seed surface, and at the same time make the seeds fully absorb water, creating favorable conditions for subsequent germination. The water absorption rate of the seeds can reach 60% - 80% of their own weight to ensure the normal progress of internal physiological activities of the seeds. After the water immersion treatment, the seeds are mixed with a mineral substrate with a particle size of 0.1-5 mm in a predetermined ratio. The mineral substrate can be selected as pure river sand, which has good air permeability and water retention. The mixing ratio can be adjusted according to the size, shape of the seeds and the characteristics of the substrate. Generally, the volume ratio of seeds to substrate is 1:(2-5). For example, for Cotoneaster seeds, a volume ratio of seeds to substrate of 1:3 can be used for mixing to ensure that the seeds are evenly distributed in the substrate and obtain a good air-permeable and moisture-retaining environment. Then the mixed seeds are put into a breathable container, such as a nylon mesh bag or a woven bag. The air permeability of the container should be good to ensure that the seeds can exchange gases with the outside air inside the container. After the seeds are put into the container, they are subjected to oscillating homogenization treatment. The oscillating equipment can be a reciprocating oscillator, with the oscillation frequency set at 50-100 times per minute, the amplitude at 10-20 mm, and the duration at 5-10 minutes. Through oscillation, the seeds and the substrate are fully mixed evenly, ensuring that the seeds are in the same environmental conditions during stratification and improving the germination uniformity.Before burying the shaken and homogenized seed containers above the previously laid coarse-grained substrate layer, the spacing between the containers should be moderate, generally 10 - 20 cm, to ensure that the seeds can receive uniform low-temperature treatment during stratification and facilitate subsequent management operations. When applying the secondary covering substrate, the thickness of the covering substrate should ensure that the distance between the top of the seed container and the ground surface is ≥ 25 cm. The covering substrate can be selected from the same material as the coarse-grained substrate or other suitable substrates according to actual needs, such as leaf mold, compost, etc., to provide suitable heat preservation, moisture retention, and air permeability. During the process of filling the substrate, it should be filled in layers, with each layer about 10 cm thick. After filling, gently compact it to ensure close contact between the substrate and the seed container, which is also beneficial to the stability of the substrate and the uniform temperature reception of the seeds. Then, implement hydraulic settlement and substrate compensatory filling. Hydraulic settlement is achieved by watering an appropriate amount of water on the substrate. The watering speed should be controlled at 10 - 20 liters per square meter per hour, so that the substrate naturally settles under the action of water to fill the voids. After watering, observe the settlement situation of the substrate and conduct compensatory filling of the substrate according to the settlement amount until the predetermined covering thickness is reached, which can ensure the stability of the buried seeds and make the seeds in a relatively stable and suitable environment during the entire stratification period, conducive to breaking the dormancy of the seeds and laying a foundation for the smooth germination after spring sowing.

[0040] It should also be clear that in the embodiments of the present application, in the spring of the second year, when the temperature gradually rises and stabilizes in the suitable temperature range for the germination of the water cotoneaster seeds, generally the local daily average temperature is stable at 10-15 degrees Celsius for 5 consecutive days, sowing can be carried out, and the temperature conditions at this time are conducive to the germination of seeds and the growth of seedlings, and can improve the germination rate of seeds and the survival rate of seedlings. The greenhouse seedbed should be disinfected in advance, and potassium permanganate solution, formalin and other disinfectants can be used for spray disinfection. The concentration of the disinfectant should be prepared according to the product manual. Generally, the concentration of potassium permanganate solution is 0.1% to 0.2%, and the concentration of formalin solution is 1% to 3%. After disinfection, ventilation is carried out for 24-48 hours to ensure that there is no residual drug damage and provide a sterile and healthy growth environment for the seedlings. The land in the greenhouse is deep-turned to a depth of 20-30cm to loosen the soil and improve its aeration and water retention. Then, according to the size of the greenhouse and actual needs, a rectangular seedbed is made. The length of the seedbed is generally 1-2 meters, the width is 1-1.5 meters, and the height is 15-20cm. The surface of the seedbed should be flat and fine, without obvious clods and debris, which is conducive to seed sowing and root growth. Then set the sowing depth to 5-15cm. According to factors such as different soil textures and seed sizes, the sowing depth should be reasonably adjusted on the premise that the seeds can germinate and emerge smoothly. Generally, shallow sowing can be appropriately performed on seedbeds with lighter soil texture and finer particles, and deep sowing can be appropriately performed on the contrary. For example, on sandy loam, the sowing depth can be set to 5-8cm, and on clay loam, the sowing depth can be set to 10-15cm. Then, a covering system consisting of multiple layers of heterogeneous substrates is constructed. For example, the following structure can be used: nutrient soil layer: 5-10 cm thick, which can be prepared in a certain proportion, including leaf humus, compost, river sand, etc., of which leaf humus accounts for 40% to 50%, compost accounts for 30% to 40%, and river sand accounts for 20% to 30%. The nutrient soil layer can provide the nutrients required for the initial growth of seedlings and promote the healthy growth of seedlings. The water-retaining material layer, with a thickness of 3-5 cm, can use materials with good water-retaining properties such as coconut bran and peat. This layer can maintain soil moisture, reduce water evaporation, and provide stable moisture conditions for seed germination and seedling growth. The breathable material layer, with a thickness of 2-3 cm, can use materials with good breathability such as perlite and vermiculite. The breathable material layer is conducive to regulating the air permeability of the soil, preventing soil compaction, and ensuring that the seedling roots can breathe normally. The multi-layer covering system is conducive to regulating the water, air, and fertilizer conditions of the soil, creating a good soil environment for seed germination and seedling growth.

[0041] It should be clear that in this application, for soil moisture monitoring and preset threshold setting, the humidity of the seed layer is monitored in real time through a soil moisture sensor. Generally, 3-5 monitoring points are evenly set in each seedbed. According to the humidity requirements for the germination of Cotoneaster seeds and the growth of seedlings, the preset threshold range of the seed layer humidity is set to 60% - 80% of the field capacity. The field capacity can be determined through the soil water characteristic curve or field measurement methods, and generally can be measured by the weighing method or the tensiometer method. In the stage division and control strategy of gradient irrigation, from after sowing to before the seedlings emerge from the soil, at this stage, the seeds begin to imbibe water and have a large water demand. The soil moisture can be controlled at 70% - 80% of the field capacity. According to the soil moisture condition and evaporation amount, timely irrigation is carried out. It should be noted that during irrigation, it is necessary to avoid the seeds being in the irrigation water for a long time, which may cause the seeds to be damaged or unable to germinate. The irrigation time is preferably selected in the morning or evening to avoid rapid water evaporation caused by irrigation during high-temperature periods. From when the seedlings emerge to before the true leaves unfold, at this stage, the water demand of the seedlings is quite stable. The soil moisture is controlled at 60% - 70% of the field capacity. According to the soil moisture monitoring data, irrigation is carried out every 1 - 2 days, and the irrigation amount per time is 3 - 5 liters per square meter. As the seedlings grow, the irrigation frequency is gradually reduced and the irrigation amount per time is increased to promote the downward growth of the seedling roots. After the true leaves unfold to before the seedlings overwinter, at this stage, the growth rate of the seedlings accelerates and the water demand increases, but it is also necessary to prevent excessive soil moisture from causing the seedlings to grow spindly and diseases to occur. The soil moisture is controlled at 60% - 70% of the field capacity. According to the weather conditions and soil moisture condition, irrigation is carried out every 3 - 5 days, and the irrigation amount per time is 5 - 8 liters per square meter. In rainy weather, the irrigation amount can be appropriately reduced or irrigation can be suspended according to the rainfall amount.

[0042] It should be clear that in the embodiments of the present application, during the overwintering germination stage, the critical period of outdoor soil freezing is determined. The critical period of outdoor soil freezing refers to the period when the local soil is about to freeze. This period is usually related to factors such as local climate conditions and soil texture, and can be determined by referring to local meteorological data and soil temperature monitoring results. When the surface temperature of the soil is continuously lower than 0 °C for 3 days and the soil moisture content is 40% - 60% of the field capacity, it can be considered that the soil has entered the critical period of soil freezing. At the same time, based on the critical period of outdoor soil freezing, saturated light is applied to the greenhouse seedbed. Saturated light means providing sufficient light for the seedlings. The light intensity and duration should meet the requirements of the seedlings' photosynthesis. Generally, the light intensity can be controlled at 30000 - 50000 lux, and the light duration is not less than 12 - 14 hours per day. The light can be precisely regulated through lighting adjustment devices installed in the greenhouse, such as sunshade nets and supplementary lights, to ensure that the seedlings can receive sufficient light during the entire overwintering period and the spring germination stage, promoting photosynthesis and providing energy for the growth of the seedlings. In the present application, for the continuous air exchange mode, by synchronously starting the continuous air exchange mode of the greenhouse ventilation system, the greenhouse ventilation system can adopt a combination of natural ventilation and forced ventilation. Natural ventilation can be carried out by opening the doors, windows, ventilation openings, etc. of the greenhouse, and forced ventilation can be carried out using devices such as fans. The ventilation volume and frequency should be adjusted according to factors such as the temperature, humidity, and carbon dioxide concentration in the greenhouse. Generally, ventilation and air exchange can be carried out regularly every day, and each ventilation time is not less than 30 minutes to ensure sufficient air exchange between the inside and outside of the greenhouse, providing fresh air for the seedlings and removing harmful gases. During the overwintering germination period, environmental parameter monitoring devices such as temperature, humidity, and carbon dioxide concentration are installed to monitor the environmental conditions in the greenhouse in real time. According to the monitoring data, the ventilation, sunshade, humidification, etc. devices in the greenhouse are automatically regulated through an intelligent control system, controlling the temperature in the greenhouse at -5 - 20 °C, the humidity at 40 - 70 °C, and the carbon dioxide concentration at 300 - 1000 ppm, creating good environmental conditions for the healthy growth and smooth overwintering of the seedlings until the group germination of the seedlings is completed in the spring of the third year, laying a solid foundation for cultivating high-quality Cotoneaster multiflorus seedlings.

[0043] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended embodiments and their equivalents.

Claims

1. A method for breeding seeds of Cotoneaster spp., characterized in that: The following steps are involved: In the low temperature stratification stage, a stratification pit is dug in a shaded and ventilated site at the end of autumn of the first year, and a coarse-grained matrix layer with a thickness of ≥ 20 cm is laid at the bottom of the pit; The mature seeds of Cotoneaster polyphylla are soaked in water and mixed with a mineral matrix with a particle size of 0.1-5 mm in a predetermined ratio, placed in a breathable container for oscillation homogenization, buried above the matrix layer and covered with the matrix twice to the top of the seed container with a distance of ≥25 cm from the surface, and then subjected to hydraulic sedimentation and matrix compensation filling; In the greenhouse sowing stage, the stratified seeds are sown in the greenhouse seedbed in the spring of the second year, the sowing depth is set to 5-15 cm, and a covering system consisting of multiple layers of heterogeneous substrates is constructed. After sowing, a gradient irrigation control strategy is implemented to maintain the moisture content of the seed layer at a preset threshold; During the germination stage after wintering, the greenhouse seedling bed is treated with real-time saturated light based on the critical period of outdoor soil freezing, and the continuous air exchange mode of the greenhouse ventilation system is started synchronously until the germination of the seedling group is completed in the spring of the third year.

2. The method for breeding seeds of Cotoneaster spp. according to claim 1, characterized in that: The geometric parameters of the stratification pit in the low-temperature stratification stage satisfy the aspect ratio of ≤1.5, the depth is 0.8-1.2m, the coarse-grained matrix layer is composed of river sand with a particle size of 0.5-3mm, and the laying thickness is 25-35cm.

3. The method for breeding seeds of Cotoneaster spp. according to claim 1, characterized in that: In the low-temperature stratification stage, the mixing volume ratio of seeds to mineral matrix is ​​1:2-1:4, and the shaking treatment adopts a mechanical shaking device with a shaking intensity of 20-50 Hz and a treatment time of 5-10 minutes.

4. The method for breeding seeds of Cotoneaster spp. according to claim 1, characterized in that: The heterogeneous matrix covering system in the greenhouse sowing stage includes a composite structure of a bottom layer of highly permeable matrix and a top layer of water-retaining matrix, wherein the thickness of the bottom layer matrix is ​​20-25 cm, the thickness of the top layer matrix is ​​2 cm-5 cm, and the sand content of the bottom layer matrix is ​​≥40%.

5. The method for breeding seeds of Cotoneaster spp. seedlings according to claim 1, characterized in that: The gradient irrigation control strategy in the greenhouse sowing stage includes: The first irrigation makes the soil moisture content reach 80% to 100% of the field water holding capacity; Subsequent irrigation is regulated in real time based on feedback data from the soil moisture sensor to maintain the moisture content of the seed layer in the range of 55% to 75%.

6. The method for breeding seeds of Cotoneaster spp. seedlings according to claim 1, characterized in that: The continuous air exchange mode in the overwintering budding stage is achieved by regulating the opening of the greenhouse vents, so that the average daily temperature in the greenhouse fluctuates within a range of -8°C to +10°C in winter and the relative humidity of the air is ≤70%.

7. The method for breeding seeds of Cotoneaster spp. according to claim 1, characterized in that: The water application rate of saturated irrigation in the winter budding stage is 250-400m³ / hm², and is implemented twice: the first irrigation is completed within 7 days before the soil freezes, and the second irrigation is implemented within 15 days after freezing, and the supplementary irrigation amount is 15% to 35% of the first irrigation.

8. The method for breeding seeds of Cotoneaster spp. according to claim 1, characterized in that: The breathable container is a woven bag.

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