A sunshade net for light control of tea plant roots and a preparation method thereof

Abstract

The application relates to the technical field of sunshade nets and discloses a sunshade net for light control of matcha planting roots and a preparation method. The sunshade net is knitted by alternately distributing blue flat wires and silver flat wires, the blue flat wires are matched with high and low refractive fillers, the blue flat wires have optical unevenness, can softly transmit blue light, good scattering illumination is formed on leaf parts and root parts of tea trees, a good blue light quality environment is constructed for tea leaves, and formation of amino acids and nitrogen-containing aromatic substances of the tea leaves is promoted; the silver flat wires have good light reflection performance, the transmission of ultraviolet rays is reduced, high temperature generated by the sunshade net directly covering the tea umbrella is avoided, and generation of tea polyphenols with a bitter and astringent taste is reduced, so that the quality requirements of the matcha are met. The sunshade net is suitable for precise light control in a tea garden field and umbrella surface direct covering shading, has a remarkable effect on improving the quality of the matcha, and can be produced and used on a large scale.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sunshade net, in particular to a sunshade net for light control of matcha planting root system and a preparation method thereof. BACKGROUND

[0002] Matcha is a fine powder tea product made of fresh tea leaves of tea plants by hot air fixation, drying, grinding and processing. With the popularization of tea-containing foods, the demand for matcha is growing rapidly. Since matcha is often used in combination with traditional food industry raw materials, it is required that the flavor characteristics of tea be outstanding and stable. This puts higher requirements on the directional regulation and control of stable tea quality cultivation technology.

[0003] Tea plants belong to light-loving plants, but the requirement of tea plants for light is neither too strong nor too weak, and they prefer scattered light rather than direct and intense sunlight. Direct strong light can cause damage to tea plants, especially in summer, high temperature and strong light can promote the generation of tea polyphenols, such as the generation of a large amount of bitter flavonoid glycosides, which can make the bitterness of tea leaves heavier, greatly limiting the use of raw materials for matcha. In addition, light quality environment is extremely critical to the formation of tea quality ingredients. According to existing research, blue and purple light can promote the formation of tea amino acids, proteins and nitrogen-containing aromatic substances, and the content of tea polyphenols is low, which is very beneficial to the formation of tea quality, and is suitable for raw materials for matcha.

[0004] Shading cover cultivation technology can significantly change the composition of tea. At present, black sunshade net cover technology is usually used to cultivate matcha, which can significantly increase the content of chlorophyll in tea leaves by reducing direct sunlight and increasing diffuse light, reduce the bitterness of tea leaves, and improve the freshness. However, at the same time, the transmission of blue light is also weakened, which limits the improvement of tea quality ingredients.

[0005] In another aspect, most of the existing tea plant cover treatment technologies use the traditional method of erecting a shed with a stand. This method is not conducive to the full mechanization of tea garden operation, affects production efficiency, and the large-scale use of stand in tea garden requires huge investment, consumes a lot of labor for net covering and removing, and increases the cost of management and maintenance. Therefore, the direct covering mode of tea pen is the main development direction of future tea garden cover treatment, which helps to realize the full mechanization of tea garden operation, and the use and promotion of riding type tea picking machine.

[0006] However, the widely used black sunshade net is easy to absorb heat, and if it is directly covered on the tea pen, it can cause the tea plants to be in a high temperature environment, which can easily cause the phenomenon of bud leaves being burned by high temperature, affecting the growth and quality of tea shoots. Moreover, the roots of tea plants are easy to evaporate in a high temperature environment. SUMMARY

[0007] In order to reduce the influence of strong ultraviolet light on the quality of tea leaves, improve the biomass of tea trees, and solve the problem that the black sunshade net used for straight cover tea canopy is easy to cause bud and leaf burning and affect the quality of fresh leaves, the application provides a sunshade net for light control of tea planting root systems and a preparation method, which effectively prevents the transmission of ultraviolet light by preparing a sunshade net with blue flat wires and silver flat wires distributed alternately, increases the transmission of blue light, and creates a cool growing environment for tea trees. Not only is helpful to the growth of tea trees, but also can significantly improve the quality of tea leaves to meet the quality requirements of tea.

[0008] In order to achieve the above-mentioned purpose, the application provides the following technical scheme:

[0009] A sunshade net for light control of tea planting root systems, characterized in that the sunshade net is distributed with blue flat wires and silver flat wires alternately, and is fixed by weaving lines distributed at equal intervals along the length direction of the flat wire strip; wherein:

[0010] The width of the blue flat wire is 5-8mm, and the thickness is 40-60μm, which is obtained by hot stretching after hot melt extrusion film casting and blade sectioning of high-density polyethylene, dispersing agent, titanium dioxide, magnesium fluoride and blue color powder;

[0011] The width of the silver flat wire is 5-8mm, and the thickness is 60-100μm, which is obtained by hot stretching after hot melt extrusion film casting and blade sectioning of high-density polyethylene, dispersing agent, glass microspheres, zinc sulfide and carbon black.

[0012] As a preferred, the light blocking rate of the sunshade net is 70-85%.

[0013] As a preferred, the blue flat wire is prepared according to the mass ratio of high-density polyethylene, dispersing agent, titanium dioxide, magnesium fluoride and blue color powder (90-95):(2-3):(0.5-1.0):(0.5-1.0):(0.05-0.08).

[0014] As a preferred, the particle size distribution of titanium dioxide D80 is 0.1-0.5μm.

[0015] As a preferred, the particle size distribution of magnesium fluoride D90 is 1-2μm.

[0016] As a preferred, the blue color powder selects at least one of pigment blue 60 (CAS number: 81-77-6), pigment blue 15:2 (CAS number: 12239-87-1) and pigment blue 15 (CAS number: 147-14-8).

[0017] The blue flat yarn has good blue light transmittance and ultraviolet blocking property. Meanwhile, titanium dioxide has a high refractive index, rutile titanium dioxide has a refractive index of 2.76, anatase titanium dioxide has a refractive index of 2.55; magnesium fluoride has a low refractive index of 1.38; the refractive index of high-density polyethylene is about 1.52; by using fillers with different refractive indexes in the blue flat yarn, the blue flat yarn has optical inhomogeneity, and light is refracted multiple times when the light transmits, thereby forming good scattering.

[0018] Preferably, the silver flat yarn is prepared from high-density polyethylene, dispersant, glass microspheres, zinc sulfide and carbon black in a mass ratio of (90-95):(2-3):(1-2):(1-2):(0.2-0.3).

[0019] Preferably, the glass microspheres have a particle size of 10-50 μm and a sphericity of 85% or more; the glass microspheres have good high dispersibility and flowability, and the sphericity enhances the light reflection effect of the silver flat yarn.

[0020] Preferably, the zinc sulfide has a particle size distribution of 0.3-0.5 μm. The zinc sulfide has a high refractive index of 2.35-2.37 and good luster, which makes the surface of the silver flat yarn have a significant light reflection effect, so that the sunshade net has a light reflection and cooling performance.

[0021] The silver flat yarn uses the combination of glass microspheres, zinc sulfide and carbon black to form a silver surface and has good light reflection performance and reduces the transmittance of ultraviolet rays.

[0022] Preferably, the dispersant is at least one of polyethylene wax, stearic acid, ethylene bis-stearamide, ethylene bis-oleamide and zinc stearate; the dispersant mainly increases the dispersibility of the pigments and the hot flow processing performance of the high-density polyethylene, reduces the carbon deposition of the T-shaped extrusion die and improves the surface luster of the flat yarn.

[0023] Further, the application provides a preparation method of the sunshade net for light control of tea plant roots, which specifically comprises the following steps:

[0024] S1. Preparing blue flat yarn: high-density polyethylene, dispersant, titanium dioxide, magnesium fluoride and blue pigment are uniformly stirred in a color mixer in a mass ratio of (90-95):(2-3):(0.5-1.0):(0.5-1.0):(0.05-0.08), and then sent to a twin-screw extruder for hot melt mixing, extruded into a sheet-shaped melt through a T-shaped die, and then drawn to a roller for pre-stretching, cooled to form a film, cut into a flat yarn embryo by a cutting knife holder, further preheated by a roller, drawn and stretched, and wound into a spool by a yarn winding machine to obtain the blue flat yarn.

[0025] S2. Prepare silver color flat yarn: high density polyethylene, dispersing agent, glass microspheres, zinc sulfide, carbon black are stirred uniformly in a color mixer according to the mass ratio (90-95):(2-3):(1-2):(1-2):(0.2-0.3), and are sent to a double screw extruder for hot melt mixing, extrusion, and extrusion into a sheet-shaped melt through a T-shaped die; the sheet-shaped melt is cast onto a roller, and is pre-stretched through multiple groups of roller rotation and cooling to form a film; the film is cut into a flat yarn embryo through a filament cutting knife holder, and is further preheated and drawn through a roller to form a spool through a take-up machine, so that a silver color flat yarn is obtained;

[0026] S3. The blue color flat yarn and the silver color flat yarn are distributed alternately through a netting machine, and are fixed by being knitted through knitting lines distributed at equal intervals along the length direction of the flat yarn strip to form a flat knitting net; dense knitting lines are arranged on the inner side of the net edge to form a connecting reinforcing part; the net edge is folded inward after being locked to form an edge fixing part, and is wound to obtain a sunshade net for shading tea planting root systems.

[0027] As a preferred, the double screw extruder is selected as a SHJ-75 type double screw extruder, the screw diameter is 75 mm, and the temperature control of each heating zone is as follows: zone 1, 160-180 DEG C; zone 2, 190-200 DEG C; zone 3, 210-220 DEG C; zone 4, 210-220 DEG C; zone 5, 220-230 DEG C; and the T-shaped die, 210-220 DEG C.

[0028] As a preferred, the roller preheating temperature is 100-120 DEG C; the drawing ratio of the traction stretching is controlled to be 3-8 times; and the linear speed of the traction stretching is greater than or equal to 300 m / min. By controlling the drawing ratio, the width of the blue color flat yarn is controlled to be 5-8 mm, and the thickness is controlled to be 40-60 mu m; and the width of the silver color flat yarn is controlled to be 5-8 mm, and the thickness is controlled to be 60-100 mu m. By high-speed stretching, the molecular chain of high density polyethylene (HDPE) is oriented along the stretching direction, so that the tensile strength of the flat yarn is increased.

[0029] As a preferred, when the flat knitting net is knitted, the interval of the knitting lines distributed at equal intervals is controlled to be 5-8 cm; and the dense knitting lines are arranged on the inner side of the net edge, and the interval of the dense knitting lines is 1-1.5 cm.

[0030] The present application increases the blue light selective permeability and scattering of the blue color flat yarn, enhances the light reflection of the silver color flat yarn, and uses the sunshade net knitted by the blue color flat yarn and the silver color flat yarn to avoid the high temperature generated by the sunshade net directly covering the tea canopy from affecting the growth of new leaf tips, change the light quality environment, reduce the leaf surface and root system temperature, enhance the root system shade, reduce the content of tea polyphenols, improve the amino acid level of tea leaves, reduce the phenolic acid ratio of tea leaves, and improve the quality of tea leaves.

[0031] Compared with the prior art, the present application has the following beneficial effects:

[0032] 1. The present application effectively reflects ultraviolet light by preparing a sunshade net with blue flat filaments and silver flat filaments arranged alternately, and selectively transmits blue light.

[0033] 2. The blue flat filaments of the sunshade net of the present application are matched with high and low refractive fillers, so that the blue flat filaments have optical inhomogeneity, have good blue light transmittance, and cause light to be refracted multiple times, so that the blue light is gently transmitted, thereby forming good scattering illumination on the leaf and root parts of the tea tree, creating a good blue light quality environment for the tea leaves, promoting the formation of amino acids and nitrogen-containing aromatic substances in the tea leaves, and significantly improving the quality of the tea leaves.

[0034] 3. The sunshade net of the present application uses silver flat filaments, has good light reflection performance, reduces the transmission of ultraviolet light, avoids the generation of high temperature by the sunshade net directly covering the tea umbrella, affects the growth of new shoots, creates a cool growing environment for the roots of the tea tree, and reduces the generation of tea polyphenols with a bitter taste, to meet the quality requirements of matcha.

[0035] 4. The sunshade net of the present application is suitable for precise light control in tea gardens and direct covering of the sunshade net, and has a significant effect on improving the quality of matcha, and can be produced and used on a large scale. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a schematic diagram of a sunshade net for root light control of matcha planting of the present application. The reference signs are explained as follows: 1 - blue flat filament; 2 - silver flat filament; 3 - braided wire; 4 - lock edge.

[0037] Figure 2 is a photograph of the sunshade net for root light control of matcha planting obtained in Example 1. DETAILED DESCRIPTION

[0038] In order to make the technical solutions and advantages of the present application clearer, the present application is further described in detail, including explicit description by figures, and the described embodiments are only part of the embodiments of the present application, not all the embodiments. Based on the common knowledge in the art, the materials, equipment and processes not explicitly defined are conventional technologies that can be understood by those skilled in the art

[0039] Example 1

[0040] S1. Preparation of blue flat yarn: Take high density polyethylene (Braskem PE SHE150, Brazil Braskem) 95 kg, polyethylene wax 2.5 kg, titanium dioxide (rutile type, particle size distribution of D80 is 0.1-0.5 μm) 1.0 kg, magnesium fluoride (particle size distribution of D90 is 1-2 μm) 0.8 kg, pigment blue 60 is 0.06 kg, stirring uniformly in the color mixer, sent to SHJ-75 type double screw extruder, the temperature control of each heating zone is: zone 1 180℃; Zone 2 190℃; Zone 3 210℃; Zone 4 220℃; Zone 5 230℃; T die 220℃; hot melt mixing extrusion, extruded into a sheet melt at the T die; The sheet melt is cast onto the roller, pre-stretched by multiple groups of roller rotation, cooled to form a film, the film is cut into flat yarn embryo by the cutting knife holder, further preheated to 115℃ by the roller, the linear speed of traction stretching is adjusted to 400 m / min, the stretching ratio is controlled to 6 times, and the yarn is wound into a spool by the yarn winder, obtaining a blue flat yarn with a width of 5 mm and a thickness of 60 μm;

[0041] S2. Preparation of silver flat yarn: Take high density polyethylene (Braskem PE SHE150, Brazil Braskem) 91 kg, ethylene bis oleic acid amide 2 kg, glass microspheres (particle size is 10-50 μm, sphericity ≥ 85%) 1.5 kg, zinc sulfide (Sachtolith HD-S, average particle size 0.3 μm, Germany Sachtolith) 1.5 kg, carbon black (660R, Cabot) 0.25 kg; First, the glass microspheres, zinc sulfide and carbon black are mixed with ethylene bis oleic acid amide, then the high density polyethylene is stirred uniformly in the color mixer, and then sent to the SHJ-75 type double screw extruder, the temperature control of each heating zone is: zone 1 180℃; Zone 2 190℃; Zone 3 210℃; Zone 4 220℃; Zone 5 230℃; T die 220℃; hot melt mixing extrusion, extruded into a sheet melt at the T die; The sheet melt is cast onto the roller, pre-stretched by multiple groups of roller rotation, cooled to form a film, the film is cut into flat yarn embryo by the cutting knife holder, further preheated to 110℃ by the roller, the linear speed of traction stretching is adjusted to 300 m / min, the stretching ratio is controlled to 4 times, and the yarn is wound into a spool by the yarn winder, obtaining a silver flat yarn with a width of 7 mm and a thickness of 80 μm;

[0042] S3. The blue flat yarn and the silver flat yarn are distributed alternately by the netting machine, and are fixed by weaving along the equidistantly distributed weaving lines in the length direction of the flat yarn strip to form a plain net, the spacing of the weaving lines is controlled to be 5 cm; A dense weaving line is arranged on the inner side of the net edge, the spacing of the dense weaving line is 1 cm, forming a connecting reinforcing part; The edge of the net is folded inward and locked after the edge of the net is folded inward, forming an edge fixing part, and winding, obtaining a sunshade net for light control of tea plant root system.

[0043] As shown in the accompanying Figure 1The schematic diagram of the sunshade net for light control of the roots of tea plantation. The blue flat yarn (1) and silver flat yarn (2) are arranged alternately, and the flat net is formed by weaving and fixing through the weaving line (3). The dense weaving line is arranged on the inner side of the net edge, and the distance between the dense weaving lines is 1 cm, forming the connecting reinforcing part. The lock edge (4) is formed by folding inward at the net edge.

[0044] The actual photos of the sunshade net for light control of the roots of tea plantation are shown in the following figures. Figure 2 The actual photos of the sunshade net for light control of the roots of tea plantation are shown in the following figures.

[0045] Example 2

[0046] S1. Prepare blue flat yarn: weigh 95 kg of high-density polyethylene (Braskem PE SHE150, Brazil Braskem), 2 kg of stearic acid, 0.5 kg of titanium white powder (anatase type, particle size distribution of D80 is 0.3-0.5 μm), 0.5 kg of magnesium fluoride (particle size distribution of D90 is 1-2 μm), 0.08 kg of pigment blue 15:2, and mix them uniformly in a color mixer. Then send them to a SHJ-75 type double screw extruder, and control the temperature of each heating zone as follows: zone 1 160℃; zone 2 190℃; zone 3 210℃; zone 4 220℃; zone 5 230℃; T-shaped die 210℃; extrude by hot melt mixing, then extrude into sheet-shaped melt through T-shaped die; cast the sheet-shaped melt onto a roller, and form a film by pre-stretching through multiple groups of roller rotation and cooling. Then cut the film into flat yarn embryos through a filament cutting knife holder, further preheat them to 120℃ through a roller, adjust the linear speed of the traction stretching to 450 m / min, control the stretching ratio to 7 times, wind them into spools through a yarn take-up machine, and obtain blue flat yarn with a width of 5 mm and a thickness of 50 μm.

[0047] S2. Preparation of silver colored flat yarn: Take high density polyethylene (Braskem PE SHE150, Brazil Braskem) 90 kg, ethylene bis-stearamide 2 kg, glass microspheres (particle size 10-50 μm, sphericity ≥ 85%) 2.0 kg, zinc sulfide (Sachtolith HD-S, average particle size 0.3 μm, Germany Sachtolith) 1.5 kg, carbon black (660R, Cabot) 0.2 kg; first mix the glass microspheres, zinc sulfide, carbon black with ethylene bis-stearamide, then mix with high density polyethylene in a color mixer, and then send to a SHJ-75 type double screw extruder, the temperature control of each heating zone is: zone 1 180℃; zone 2 200℃; zone 3 220℃; zone 4 220℃; zone 5 230℃; T-shaped die port 220℃; hot melt mixing and extrusion, then extruded into a sheet-shaped melt through a T-shaped die; the sheet-shaped melt is cast onto a roller, pre-stretched by multiple groups of roller rotation, cooled to form a film, the film is cut into a flat yarn embryo by a cutting knife holder, further preheated to 100℃ by a roller, the linear speed of traction stretching is adjusted to 300 m / min, the stretching ratio is controlled at 4 times, and the yarn is wound into a spool by a take-up machine, obtaining a silver colored flat yarn with a width of 6 mm and a thickness of 85 μm;

[0048] S3. Intermittently distribute the blue colored flat yarn and the silver colored flat yarn through the netting machine, and fix them by weaving along the length direction of the flat yarn strip at equal intervals to form a flat needle net, the interval of the weaving line is controlled at 6 cm; dense weaving lines are arranged on the inner side of the net edge, the interval of the dense weaving lines is 1.5 cm, forming a connecting reinforcing part; the net edge is folded inward and locked after the edge is formed, forming an edge fixing part, and winding, obtaining a sunshade net for light control of tea plant root system.

[0049] Example 3

[0050] S1. Preparation of blue colored flat yarn: Take high density polyethylene (Braskem PE SHE150, Brazil Braskem) 90 kg, stearic acid 2 kg, titanium white (anatase type, particle size distribution of D80 is 0.3-0.5 μm) 1 kg, magnesium fluoride (particle size distribution of D90 is 1-2 μm) 1 kg, pigment blue 15:2 0.06 kg, mix in a color mixer, and then send to a SHJ-75 type double screw extruder, the temperature control of each heating zone is: zone 1 160℃; zone 2 190℃; zone 3 210℃; zone 4 220℃; zone 5 230℃; T-shaped die port 210℃; hot melt mixing and extrusion, then extruded into a sheet-shaped melt through a T-shaped die; the sheet-shaped melt is cast onto a roller, pre-stretched by multiple groups of roller rotation, cooled to form a film, the film is cut into a flat yarn embryo by a cutting knife holder, further preheated to 120℃ by a roller, the linear speed of traction stretching is adjusted to 450 m / min, the stretching ratio is controlled at 6 times, and the yarn is wound into a spool by a take-up machine, obtaining a blue colored flat yarn with a width of 6 mm and a thickness of 60 μm;

[0051] S2. Preparation of silver colored flat yarn: 90 kg of high density polyethylene (Braskem PE SHE150, Brazil Braskem), 2 kg of ethylene bis-stearamide, 2.0 kg of glass microspheres (particle size 10-50 pm, sphericity ≥ 85%), 2 kg of zinc sulfide (Sachtolith HD-S, average particle size 0.3 pm, Germany Sachtolith), 0.3 kg of carbon black (660R, Cabot) were weighed; first, the glass microspheres, zinc sulfide, carbon black were mixed with ethylene bis-stearamide, then the high density polyethylene was stirred uniformly in a color mixer, and then sent to a SHJ-75 type double screw extruder, the temperature control of each heating zone was: zone 1 180°C; zone 2 200°C; zone 3 220°C; zone 4 220°C; zone 5 230°C; T-shaped die port 220°C; hot melt mixing and extrusion, then T-shaped die port extrusion into sheet-shaped melt; the sheet-shaped melt was cast onto the roller, and through multiple groups of roller rotation pre-stretching, cooling to form a film, the film was cut into flat yarn embryos by a filament cutter frame, and further preheated to 100°C by a roller, the linear speed of the traction stretching was adjusted to 300 m / min, and the stretching ratio was controlled at 3 times, and the yarn was wound on the take-up machine to obtain a silver colored flat yarn with a width of 6 mm and a thickness of 100 pm;

[0052] S3. The blue colored flat yarn and the silver colored flat yarn were distributed alternately by a netting machine, and were fixed by weaving through the weaving lines distributed at equal intervals along the length direction of the flat yarn strip to form a plain net, the interval of the weaving lines was controlled at 8 cm; dense weaving lines were arranged on the inner side of the net edge, the interval of the dense weaving lines was 1.5 cm, and a connecting reinforcing part was formed; the net edge was folded inward and locked after the edge was folded, an edge fixing part was formed, and the net was wound to obtain a sunshade net for shading tea planting root system.

[0053] The sunshade nets of examples 1-3 and a commercially available 3-needle black sunshade net with a shading rate of 70% were used for Longjing 43# shading cultivation in Zhejiang area. In early summer, when the bud leaves grew to 1 bud and 2 leaves, the sunshade nets were directly covered on the tea tent to shade, and the tea was picked after 25 days of shading, fixed, dried and used for detecting the content of quality ingredients. The content of tea polyphenols in tea was detected according to the method of “GB / T 8313 Determination of tea polyphenols and catechins in tea”. The content of free amino acids in tea was detected according to the method of “GB / T 8314 Determination of total amount of free amino acids in tea”. By comparing with the reference sample without using the sunshade net, the change of the phenolic amino acid ratio was qualitatively analyzed, as shown in Table 1.

[0054] Table 1: Detection of tea polyphenol content, free amino acid content and phenolic amino acid ratio in tea

[0055]

[0056] Through qualitative analysis of test data, the sunshade net with blue and silver phases of the application makes full use of the transmittance and scattering of blue light, inhibits the synthesis of tea polyphenols, and promotes the accumulation of free amino acids; meanwhile, the reflection of silver color reduces the influence of ultraviolet rays and high temperature on tea leaves. In the shading treatment of straight cover tea, compared with the traditional black net, the reasonable temperature and light quality environment of tea trees can be better maintained, the generation of amino acids is promoted, the content of tea polyphenols is controlled, the lower phenol-ammonia ratio is maintained, the freshness of the finished tea is good, the bitter taste is reduced, and thus the quality needs of matcha are met.

[0057] The above describes the basic principles and main features of the application and the advantages of the application. Those skilled in the art should understand that the application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the application. Without departing from the spirit and scope of the application, various changes and improvements can be made to the application, and these changes and improvements all fall within the scope of the claimed application.

Claims

1. A shading net for light control of tea plant roots, characterized in that, The sunshade net is formed by the blue flat silk and the silver flat silk being distributed alternately and being fixed by the weaving threads being distributed equidistantly along the length direction of the flat silk strip. The light shielding rate of the sunshade net is 70-85%. The width of the blue flat silk is 5-8mm and the thickness is 40-60μm, which is obtained by hot melt extrusion casting film according to the mass ratio of high density polyethylene, dispersing agent, titanium dioxide, magnesium fluoride, blue color powder (90-95):(2-3):(0.5-1.0):(0.5-1.0):(0.05-0.08), blade sectioning and hot stretching. The width of the silver flat silk is 5-8mm and the thickness is 60-100μm, which is obtained by hot melt extrusion casting film according to the mass ratio of high density polyethylene, dispersing agent, glass microspheres, zinc sulfide, carbon black (90-95):(2-3):(1-2):(1-2):(0.2-0.3), blade sectioning and hot stretching.

2. The shading net for light control of tea plant roots according to claim 1, wherein The particle size distribution of titanium dioxide D80 is 0.1-0.5μm; the particle size distribution of magnesium fluoride D90 is 1-2μm.

3. The shading net for light control of tea plant roots according to claim 1, characterized in that, The blue color powder selects at least one of pigment blue 60, pigment blue 15:2 and pigment blue 15.

4. The shading net for light control of tea plant roots according to claim 1, wherein The particle size of the glass microspheres is 10-50μm and the sphericity is ≥85%; the particle size distribution of zinc sulfide D50 is 0.3-0.5μm.

5. The preparation method of the sunshade net for light control of the root system of Camellia sinensis according to any one of claims 1-4, specifically comprising the following steps: S1. Preparing the blue flat silk: uniformly stirring high density polyethylene, dispersing agent, titanium dioxide, magnesium fluoride and blue color powder according to the mass ratio (90-95):(2-3):(0.5-1.0):(0.5-1.0):(0.05-0.08) in a color mixer, sending to a double screw extruder for hot melt mixing, extruding into a sheet-shaped melt through a T-shaped die, casting the sheet-shaped melt onto a roller, pre-stretching through multiple groups of roller rotation, cooling to form a film, cutting the film into flat silk embryos through a slicing knife holder, further preheating and traction stretching through a roller, winding into a spool through a yarn collector, and obtaining the blue flat silk; S2. Preparing the silver flat silk: uniformly stirring high density polyethylene, dispersing agent, glass microspheres, zinc sulfide and carbon black according to the mass ratio (90-95):(2-3):(1-2):(1-2):(0.2-0.3) in a color mixer, sending to a double screw extruder for hot melt mixing and extruding, extruding into a sheet-shaped melt through a T-shaped die, casting the sheet-shaped melt onto a roller, pre-stretching through multiple groups of roller rotation, cooling to form a film, cutting the film into flat silk embryos through a slicing knife holder, further preheating and traction stretching through a roller, winding into a spool through a yarn collector, and obtaining the silver flat silk; S3. Distributing the blue flat silk and the silver flat silk alternately through a net weaving machine, and fixing by weaving threads being distributed equidistantly along the length direction of the flat silk strip to form a plain net; setting dense weaving threads on the inner side of the net edge to form a connecting reinforcing part; folding inward after locking the edge at the net edge to form an edge fixing part, winding, and obtaining a sunshade net for light control of the root system of Camellia sinensis.

6. The method of claim 5, wherein the shading net for light control of tea plant roots is prepared by using a material having a thickness of 0.05 to 0.15 mm. The roller preheating is at a temperature of 100-120 DEG C; the drawing ratio of the drawing is controlled at 3-8 times; the linear speed of the drawing is greater than or equal to 300 m / min.

7. The method of claim 5, wherein the shading net is prepared by weaving a plurality of threads of a first color and a plurality of threads of a second color. In the knitting of the flat net, the interval of the equidistantly distributed knitting lines is controlled at 5-8 cm; dense knitting lines are arranged in the inner side of the net edge, and the interval of the dense knitting lines is 1-1.5 cm.

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