Long-acting composite slow-release full-biodegradable mulching film capable of killing root nematodes and promoting growth and application of long-acting composite slow-release full-biodegradable mulching film

Abstract

The invention belongs to the field of novel agricultural materials, and particularly relates to a long-acting composite slow-release full-biodegradable mulching film capable of killing root nematodes and promoting growth and application thereof, in particular to a slow-release full-biodegradable mulching film obtained by melt blending and extrusion blow molding of an MOF-nematode-killing growth-promoting aid complex and full-biodegradable resin. Wherein the proportion of the MOF-nematode killing and growth promoting auxiliary agent complex in the mulching film is 0.5-1%. The mulching film has an extremely long nematode killing functional period and excellent mechanical properties, can effectively prevent and control damage of root nematodes to plants when being applied to cultivation of crops easily infected with root nematodes, can also improve the yield and quality of the crops, has a good promotion effect on promotion of high-valued application and green development of green polymer materials, and has a wide application prospect. And the scheme can be popularized to more crops.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of new agricultural materials, and particularly relates to a long-acting composite slow-release full-biodegradable mulch film with root nematode killing and growth promoting functions and application thereof. BACKGROUND

[0002] Root-knot nematodes are a kind of soil-borne pathogens that seriously harm tomato production and cause huge economic losses worldwide. These nematodes can form root knots by invading crop roots, which damages the absorption and transportation of water and nutrients in plants, leading to slow growth, yield reduction, and even absolute loss in severe cases. Currently, chemical nematocide is mainly used for prevention and control in agricultural production, but long-term use not only leads to nematode resistance, but also damages the soil ecological environment, threatening the safety of agricultural products and human health. Therefore, developing environmentally friendly, efficient and sustainable nematode control technology has become an important research direction in the current agricultural field.

[0003] Biodegradable mulch film as a new type of environmentally friendly agricultural material has shown broad application prospects in crop cultivation in recent years. Compared with traditional plastic mulch film, biodegradable mulch film can be decomposed by microorganisms under natural conditions, effectively reducing "white pollution", and has the functions of soil conservation, temperature increase and weed suppression. However, the currently marketed biodegradable mulch film has relatively single function, especially in the aspect of soil-borne disease control. Patent CN101803546A discloses a biodegradable agricultural mulch film that can prevent and control root-knot nematodes and its preparation method. The nematocide additive is directly blended with full-biodegradable resin to blow a thin film, which has no slow-release effect and is difficult to cover the entire growth period of crops. Therefore, how to endow the mulch film with additional functions to achieve growth promotion and disease and pest control while covering the soil is a key scientific problem to improve the application value of biodegradable mulch film. SUMMARY

[0004] In view of the blank of existing biodegradable mulch film in promoting growth and controlling diseases and pests, the application provides a long-acting composite slow-release full-biodegradable mulch film with root nematode killing and growth promoting functions and application thereof. Specifically, a MOF-nematode killing and growth promoting additive composite and full-biodegradable resin are melt-blended to obtain a slow-release full-biodegradable mulch film by extrusion blow molding, wherein the proportion of the MOF-nematode killing and growth promoting additive composite in the mulch film is 0.5-1%. The mulch film has both a very long nematode killing function period and excellent mechanical properties. When applied to tomato cultivation, it can not only effectively prevent and control the invasion of root nematodes on tomato plants, but also promote crop growth and improve tomato yield and quality. The scheme can be popularized to more crops, and has a good promoting effect on the high-value application and green development of green polymer materials.

[0005] The inventors first compound the nematicidal growth promoter with the slow-release material MOF to obtain an MOF-nematicidal growth promoter compound, and then compound it with a degradable polymer material to develop a long-acting composite slow-release full-biodegradable mulch film with nematicidal and growth-promoting effects. The film not only retains the physical advantages of traditional degradable mulch films, but also promotes crop growth and continuously inhibits the population density of nematodes in the soil through the slow-release effect of the nematicidal growth promoter. Through application tests in tomato cultivation, the prevention and control effect of the functional mulch film on root-knot nematodes and its influence on tomato growth and yield are systematically evaluated. The research results provide a new strategy of "covering-prevention" integration for tomato green production, and also provide a theoretical basis and technical reference for the research and development of functional degradable agricultural materials.

[0006] The specific technical solutions of the application are as follows: A long-acting composite slow-release full-biodegradable mulch film with nematicidal and growth-promoting effects, wherein the mass ratio of the MOF-nematicidal growth promoter compound and the full-biodegradable resin is 0.5-1:99-99.5.

[0007] The full-biodegradable resin is one or more of polyhydroxyalkanoate, polybutylene succinate, polyepsilon-caprolactone or polyvinyl alcohol, preferably polybutylene succinate.

[0008] The MOF material used in the application is a nanomaterial, and when added to the full-biodegradable resin, it can improve the mechanical properties of the material and has obvious gain effect on various properties of the finally obtained mulch film.

[0009] Preferably, the mass ratio of the MOF-nematicidal growth promoter compound and the full-biodegradable resin is 0.6-0.8:99.2-99.4.

[0010] The preparation method of the MOF-nematicidal growth promoter compound is as follows: The dried MOF is placed in a vacuum reaction tube, the rubber plug is plugged, the circulating water type vacuum pump is used for vacuumizing, and the vacuumizing is continued for 20-40 min to exhaust the air in the lumen of the MOF as much as possible to form negative pressure. The nematicidal growth promoter is dissolved in deionized water to prepare an additive solution, the additive solution is added to the vacuum tube, and the MOF and the additive solution are stirred to obtain a mixed suspension; the mixed suspension is filtered, washed, and dried to obtain a filter cake, and the filter cake is dried to obtain the MOF-nematicidal growth promoter compound.

[0011] The concentration of the nematicidal growth promoter solution is 0.01-0.2 g / mL; and the mass ratio of the MOF and the additive is 10-50:3.

[0012] The stirring time is 5-9h; the flushing is deionized water flushing, and the flushing times are 2-6 times; the drying temperature is 40-90℃.

[0013] The above-mentioned nematicidal growth promoter is selected from one or more of choline geranate, tetrabutylammonium geranate and octadecyltrimethylammonium geranate, and is preferably choline geranate. The above-mentioned nematicidal growth promoter has both nematicidal and growth-promoting functions.

[0014] The above-mentioned nematicidal growth promoter is synthesized according to the scheme of the reference (Pernak J, Czerniak K, Niemczak M, et al. Bioherbicidal ionic liquids[J]. ACS Sustainable Chemistry & Engineering, 2018, 6(2): 2741-2750.), that is, tetraalkylammonium hydroxide is reacted with geranic acid and methanol, and the product is purified, filtered, rotary evaporated and dried under reduced pressure to obtain the nematicidal growth promoter.

[0015] The tetraalkylammonium hydroxide is choline hydroxide or tetrabutylammonium hydroxide or octadecyltrimethylammonium hydroxide, and the corresponding products are choline geranate, tetrabutylammonium geranate and octadecyltrimethylammonium geranate.

[0016] The ratio of the tetraalkylammonium hydroxide, geranic acid and methanol is 2.5-3.0:1.5-2.0:20, wherein the tetraalkylammonium hydroxide is g, the geranic acid is g, and the methanol is mL.

[0017] The reaction temperature is 20-30℃, and the reaction time is 0.5-1.5h.

[0018] The purification solvent is an acetone:methanol mixed solvent (7-9:1-3).

[0019] The rotary evaporation temperature is 55-65℃.

[0020] The drying temperature is 50-80℃, and the drying time is 10-30h.

[0021] The MOF used above is prepared as follows: Zinc nitrate hexahydrate, terephthalic acid, dimethylformamide and triethylamine are reacted in a reaction kettle, and after the reaction is completed, it is cooled to room temperature. The solid product is centrifuged, washed and dried to obtain the MOF.

[0022] The ratio of the zinc nitrate hexahydrate, terephthalic acid, dimethylformamide and triethylamine is 0.5-0.7:0.1-0.2:15-25:10-15; wherein the zinc nitrate hexahydrate is in g, the terephthalic acid is in g, the dimethylformamide is in mL, and the triethylamine is in mL. The reaction temperature is 130-230 DEG C, and the reaction time is 22-30 h.

[0023] Compared with the prior art, the preparation method adopts a special drying method, specifically, when the liquid CO2 is slowly injected, the temperature of the autoclave is 0-20 DEG C, and the pressure is 5-10 MPa; when the temperature and pressure are increased to the supercritical state, the temperature of the autoclave is 30-50 DEG C, and the pressure is 8-20 MPa, and the maintaining time is 2-10 h.

[0024] Then, the supercritical CO2 is discharged from the pore channel without damage at a rate of 0.1-0.5 MPa / h, so that the MOF material perfectly maintains the pore structure. The total time from the injection of the liquid CO2 to the completion of pressure relief is controlled to be 25-35 h.

[0025] The MOF prepared by the method has a higher specific surface area, plays a better slow-release role, can load more nematocidal growth-promoting adjuvants, and achieves effective release of the nematocidal growth-promoting adjuvants.

[0026] The preparation method of the long-acting composite slow-release type full-biodegradable mulch film with the functions of killing root nematodes and promoting growth provided by the application comprises the following steps: The MOF-nematocidal growth-promoting adjuvant composite and the full-biodegradable resin are weighed, dried at 70-100 DEG C for 9-15 h, uniformly mixed in proportion, and then added into a double-screw extruder; there are three continuous temperature zones from the feeding part to the die head: 100-150 DEG C, 130-180 DEG C and 140-190 DEG C, the feeding rate is set to be 15-60 g / min, and the screw rotation speed is 10-50 rpm; then the molten composite material extruded by the double-screw extruder is cooled under the traction of a traction device, and then granulated by a granulator, so that a composite master batch is obtained, and the rotation speed of the granulator is 10-50 rpm; the obtained composite master batch is dried at 40-100 DEG C for 5-20 h, added into a single-screw extruder for melt extrusion, and blown into a mulch film by a film blowing machine.

[0027] The process temperature of the film blowing is set to be 150-180 / 145-175 / 140-170 / 135-165 / 130-160 DEG C, the screw rotation speed is 20-60 rpm, the traction rate is 5-50 Hz, and the collection rate is 5-30 Hz, so that the long-acting composite slow-release type full-biodegradable mulch film with the functions of killing root nematodes and promoting growth is obtained, and the thickness of the film is 10-20 mu m.

[0028] The above processing temperature is more suitable for the addition of the MOF-nematode-killing growth-promoting agent complex, and increases the stability of the agent in the film material.

[0029] The inventors further disclose the application of the above-mentioned long-acting composite slow-release type fully biodegradable mulch film with both nematode-killing and growth-promoting functions in tomato planting, and the tomato variety is one or more of Saint Laurent tomato, Diana tomato, and powder like wish tomato. Preferably, the tomato variety is Saint Laurent tomato. In specific application, the above-mentioned mulch film is directly used for mulching operation, and other operations can be performed according to the conventional tomato planting scheme.

[0030] In order to verify the functionality of the mulch film, potting tomatoes are used for verification test, the height of the flowerpot is 25-30 cm, and the diameter of the flowerpot is 24-28 cm; preferably, the height of the flowerpot is 27 cm, and the diameter of the flowerpot is 26 cm; the soil used for verification test is a mixture of nematode soil and nutrient medium in a ratio of 1:1.

[0031] The agent is loaded on the MOF to obtain a MOF-nematode-killing growth-promoting agent complex, which has the function of slow-release insect killing; the complex and the fully biodegradable resin are prepared by melt blending and extrusion blow molding process to have extremely long insect killing function period and excellent mechanical properties. In the application process, the MOF-nematode-killing growth-promoting agent complex constructed by the application realizes multi-stage slow release and precise delivery of the nematode-killing active ingredient due to its unique structure regulation and function integration. First, the MOF as a "molecular level reservoir" significantly delays the migration rate of the nematode-killing growth-promoting agent in the mulch film, avoiding the problems of waste of drug efficacy and failure in later period caused by initial large release. The highly ordered pore structure of the MOF material and the controllable host-guest interaction between the agent molecules can effectively load and protect the agent molecules, avoiding their premature degradation or burst release; then, the loaded molecules are released from the MOF framework through diffusion, pore desorption and environmental response (such as soil humidity, pH or enzyme action) mechanisms, and further slowly diffuse to the surface of the mulch film through the mulch film matrix, forming a uniform and continuous effective ingredient concentration gradient, so as to maintain an effective concentration sufficient to kill nematodes at the soil-mulch interface for a long time.

[0032] The beneficial effects of the application are as follows: The present application aims at the increasingly serious root-knot nematode disease in agricultural production, the easy failure of traditional chemical pesticides and the environmental pollution, and the "white pollution" problem caused by the residue of ordinary plastic mulch, and proposes a new type of slow-release full-biodegradable functional mulch. By loading the efficient nematicidal growth promoter into metal organic framework material (MOF), a MOF-nematicidal growth promoter complex with controllable release behavior is constructed, and it is compounded with full-biodegradable resin through melt blending and extrusion blow molding process, successfully preparing a full-biodegradable mulch with long-acting nematicidal growth function and excellent mechanical properties. The mulch not only retains the physical advantages of traditional degradable mulch, but also can continuously inhibit the population density of nematodes in the soil through the slow release of nematicidal growth promoters, and promote crop growth. Taking tomato as a model crop to verify the nematicidal growth efficacy, the mulch can realize multi-stage slow release of nematicidal growth promoters during use: first slowly released from the MOF channels to the mulch matrix, further migrated to the surface of the mulch, contacted with nematodes in the soil and exerted the drug efficacy. Due to the carrier regulation of MOF, the release rate of the promoter is stable and durable, which significantly prolongs the effective action time, covering the entire growth cycle of crops such as tomato, effectively preventing and controlling the infestation of root-knot nematodes, thereby improving the growth state of plants and increasing the yield and quality of tomato fruits. Compared with traditional non-slow-release mulch, the mulch not only greatly prolongs the functional effective period and avoids the need for frequent pesticide application, but also uses full-biodegradable materials for the mulch matrix, which can be naturally degraded into carbon dioxide and water in the soil after use, without the need for recovery, eliminating residual pollution, and meeting the requirements of green and sustainable development of agriculture. It provides a new idea for the design and development of functional degradable mulch, and has important significance for promoting the high-value application of green agricultural materials and agricultural pollution reduction and efficiency increase. BRIEF DESCRIPTION OF DRAWINGS

[0033] Fig. 1 is the mechanical property index of blank non-nematicidal growth film, traditional non-slow-release nematicidal growth mulch and example 3 full-biodegradable mulch; Fig. 2 is the nematicidal growth promoter release curve of traditional non-slow-release nematicidal growth mulch, example 1 and example 3 full-biodegradable mulch; Fig. 3 is the tomato root photos of example 1-3, no film and blank non-nematicidal growth film; Fig. 4 is the tomato yield index of example 1-3, no film and blank non-nematicidal growth film; Fig. 5 is the tomato quality index of example 1-3, no film and blank non-nematicidal growth film. DETAILED DESCRIPTION

[0034] The technical solutions of the present application will be further described below in combination with specific embodiments, which are only used to more specifically illustrate the technical solutions of the present application and should not be understood as limiting the scope of protection of the present application.

[0035] In the following examples, various raw materials are commercially available unless otherwise specified.

[0036] Example 1 A long-acting composite slow-release type full-biodegradable mulch film with both nematicidal and growth-promoting properties, wherein the mass ratio of MOF-nematicidal growth-promoting additive complex and full-biodegradable resin is 0.8:99.2, and the full-biodegradable resin is polybutylene succinate.

[0037] The preparation method of the above mulch film includes the preparation of the nematicidal growth-promoting additive, which includes the following steps: To 1.2 g of choline hydroxide, 20 ml of methanol solution was added, and then 1.5 g of pelargonic acid was added, and the neutralization reaction was carried out at 25°C for 1 hour. The synthesized product was purified by adding a mixture of acetone:methanol (9:1, 20 mL), and the residual precipitate was removed by filtration. Finally, the solvent was removed by rotary evaporation at 60°C, and the nematicidal growth-promoting additive choline pelargonic acid was dried at 60°C under reduced pressure for 24 hours.

[0038] The preparation method of the MOF includes the following steps: Dissolve 0.5 g of zinc nitrate hexahydrate and 0.1 g of terephthalic acid completely in 20 mL of dimethylformamide, then slowly inject 10 ml of triethylamine under stirring. Put the reactants in a stainless steel reactor, heat at 135°C for 24 hours, and then naturally cool to room temperature. After the reaction is completed, the solid precipitate is collected by centrifugation, washed with dimethylformamide and chloroform three times in turn, and soaked in chloroform for 3 days. Finally, the chloroform solvent is removed by supercritical CO2 drying: the solid is supercritically CO2 dried, the high-pressure kettle temperature is 3°C when liquid CO2 is slowly injected, the pressure is 5 MPa, the high-pressure kettle temperature is 40°C when the temperature and pressure are increased to the supercritical state, and the pressure is 10 MPa, which is maintained for 8 h. Then, the supercritical CO2 is discharged from the pores without damage at a rate of 0.2 MPa / h, and the MOF is obtained.

[0039] The preparation method of the MOF-nematicidal growth-promoting additive complex includes the following steps: Put the dried MOF into a vacuum reaction tube, plug the rubber stopper, and use a circulating water vacuum pump to vacuum for 30 min to as much as possible to remove the air in the lumen of the MOF to form negative pressure. In this way, as much nematicidal growth-promoting additive as possible can be loaded, thereby achieving effective release of the nematicidal growth-promoting additive and prolonging the effective period of nematicidal activity. Accurately weigh the nematicidal growth-promoting additive, dissolve it in deionized water, and prepare a nematicidal growth-promoting additive solution. Use a syringe to inject the additive solution into the vacuum reaction tube through the rubber stopper, and magnetically stir for 6 h; the mass ratio of MOF to nematicidal growth-promoting additive is 10:3.

[0040] The mixed suspension is filtered by using a sand core funnel, and deionized water is used to rinse 3 times to remove the free nematicide growth promoting agent outside, and the MOF-nematicide growth promoting agent composite cake obtained is dried in a vacuum drying oven at 80°C until the weight is constant. The dried MOF-nematicide growth promoting agent composite is crushed with a mortar to obtain MOF-nematicide growth promoting agent composite powder.

[0041] The preparation of the long-acting composite slow-release full-biodegradable mulch film with nematicidal and growth promoting functions comprises the following steps: The polybutylene succinate and the MOF-nematicide growth promoting agent composite are weighed and mixed uniformly at a mass ratio of 0.8:99.2 at 80°C for 10 h. The polybutylene succinate and the MOF-nematicide growth promoting agent composite are added to a double-screw extruder; there are three consecutive temperature zones from the feeding part to the die head: 130°C, 140°C, and 150°C, the feeding rate is set to 35 g / min, and the screw rotation speed is 25 rpm; then the molten composite material extruded by the double-screw extruder is cooled by a traction device, and then granulated by a granulator at a rotation speed of 25 rpm to obtain a composite master batch. The obtained composite master batch is dried at 70°C for 10 h, and then added to a single-screw extruder for melt extrusion, and then blown into a mulch film by a film blowing machine.

[0042] The process temperature of the film blowing is set to 170 / 165 / 160 / 155 / 150°C, the screw rotation speed is 50 rpm, the traction rate is 20 Hz, and the collection rate is 10 Hz, so that the slow-release full-biodegradable nematicide growth promoting mulch film is obtained. The film is packaged in a black light-proof plastic bag and stored in a dry and cool place away from light. The thickness of the slow-release full-biodegradable nematicide growth promoting mulch film is controlled to be 10±1 μm.

[0043] Example 2 A long-acting composite slow-release full-biodegradable mulch film with nematicidal and growth promoting functions, wherein the mass ratio of the MOF-nematicide growth promoting agent composite and the full-biodegradable resin is 0.6:99.4, and the full-biodegradable resin is polyhydroxyalkanoate.

[0044] The preparation method of the above-mentioned mulch film comprises the preparation of the nematicide growth promoting agent, which comprises the following steps: To 2.4 g of tetrabutylammonium hydroxide, 20 ml of methanol solution is added, and then 1.6 g of malic acid is added, and the neutralization reaction is carried out at 20°C for 0.5 h. The synthesized product is purified by adding a mixture of acetone:methanol (8:2, 10 mL), and the residual precipitate is removed by filtration. Finally, the solvent is removed by rotary evaporation at 55°C, and the product is dried at 50°C under reduced pressure for 20 h to obtain the nematicide growth promoting agent tetrabutylammonium malate.

[0045] A method for preparing MOF, comprising the following steps: Dissolve 0.6 g of zinc nitrate hexahydrate and 0.15 g of terephthalic acid in 15 mL of dimethylformamide, then slowly inject 13 mL of triethylamine under stirring. Put the reactants in a stainless steel reactor, heat at 130℃ for 22 hours, and then naturally cool to room temperature. After the reaction is completed, collect the solid precipitate by centrifugation, wash with dimethylformamide and chloroform three times in turn, and soak in chloroform for 3 days. Finally, remove the chloroform solvent by supercritical CO2 drying: supercritical CO2 dry the solid, when slowly injecting liquid CO2, the autoclave temperature is 10℃ and the pressure is 8 MPa, when increasing the temperature and pressure to the supercritical state, the autoclave temperature is 30℃ and the pressure is 15 MPa, and the pressure is maintained for 5 h. Then, smoothly release the pressure at a rate of 0.3 MPa / h to allow the supercritical CO2 to be discharged from the pores without damage, and the MOF is obtained.

[0046] A method for preparing a MOF-nematicide growth promoter complex, comprising the following steps: Accurately place an appropriate amount of dried MOF into a vacuum reaction tube, plug the rubber stopper, and perform vacuum pumping with a circulating water vacuum pump for 20 min to remove as much air as possible from the lumen of the MOF to form a negative pressure. Accurately weigh the nematicide growth promoter dissolved in deionized water to prepare a nematicide growth promoter solution, and inject the solution into the vacuum reaction tube through the rubber stopper with a syringe, and magnetically stir for 5 h; the mass ratio of MOF to nematicide growth promoter is 20:3.

[0047] Use a sand core funnel to filter the mixed suspension, rinse with deionized water twice to remove the nematicide growth promoter that is free outside, and dry the obtained MOF-nematicide growth promoter complex filter cake in a vacuum drying oven at 70℃ until the weight is constant. Grind the dried MOF-nematicide growth promoter complex with a mortar to obtain MOF-nematicide growth promoter complex powder.

[0048] A long-acting composite slow-release type fully biodegradable mulch film with nematicidal and growth-promoting properties, comprising the following steps: The MOF-nematicidal growth promoter complex and polyhydroxyalkanoate were weighed, dried at 70°C for 11 h, and mixed uniformly at a mass ratio of 0.6:99.4. The polyhydroxyalkanoate and MOF-nematicidal growth promoter complex were added to a twin-screw extruder; there were three consecutive temperature zones from the feeding part to the die head: 135°C, 145°C, and 155°C, the feeding rate was set to 40 g / min, and the screw rotation speed was 30 rpm; then the molten-state composite material extruded by the twin-screw was cooled by a traction device, and then pelletized by a pelletizer at a rotation speed of 30 rpm to obtain a composite master batch. The obtained composite master batch was dried at 80°C for 8 h, and then added to a single-screw extruder for melt extrusion, and then blown into a mulch film by a film blowing machine.

[0049] The process temperature for film blowing was set to 175 / 170 / 165 / 160 / 155°C, the screw rotation speed was 45 rpm, the traction rate was 15 Hz, and the collection rate was 15 Hz, so that the slow-release full-biodegradable nematicidal growth-promoting mulch film was obtained, which was packaged in a black lightproof plastic bag and stored in a dry, cool, and dark place. The thickness of the slow-release full-biodegradable nematicidal growth-promoting mulch film was controlled to be 15±1 μm.

[0050] Example 3: A long-acting composite slow-release full-biodegradable mulch film with nematicidal and growth-promoting properties, wherein the mass ratio of the MOF-nematicidal growth promoter complex and the full-biodegradable resin is 1:99, and the full-biodegradable resin is poly-ε-caprolactone.

[0051] The preparation method of the above mulch film includes the preparation of the nematicidal growth promoter, which includes the following steps: To 1.2 g of octadecyltrimethylammonium, 20 ml of methanol solution was added, and then 1.8 g of pelargonic acid was added, and the neutralization reaction was carried out at 30°C for 1.5 hours. The synthesized product was purified by adding a mixture of acetone:methanol (7:3, 15 mL), filtered to remove the residual precipitate, and finally the solvent was removed by rotary evaporation at 65°C, and dried at 80°C under reduced pressure for 25 hours to obtain the nematicidal growth promoter octadecyltrimethylammonium pelargonate.

[0052] The preparation method of the MOF includes the following steps: Dissolve 0.7 g of zinc nitrate hexahydrate and 0.2 g of terephthalic acid in 25 mL of dimethylformamide, then slowly inject 15 mL of triethylamine under stirring. Put the reactants in a stainless steel reactor, heat at 150℃ for 30 hours, and then cool to room temperature naturally. After the reaction is completed, collect the solid precipitate by centrifugation, wash with dimethylformamide and chloroform three times in turn, and soak in chloroform for 3 days. Finally, remove the chloroform solvent, dry the solid by supercritical CO2, and slowly inject liquid CO2 at a pressure of 10 MPa and a temperature of 20℃. When the temperature is raised to 50℃ and the pressure is raised to 20 MPa, maintain for 2 hours. Then, smoothly release the pressure at a rate of 0.5 MPa / h to allow the supercritical CO2 to be discharged from the pores without damage, and obtain the MOF.

[0053] The preparation method of the MOF-nematicide growth promoter composite includes the following steps: Accurately place an appropriate amount of dried MOF into a 50 mL vacuum reaction tube, plug the rubber stopper, and use a circulating water vacuum pump to perform vacuum pumping for 40 minutes to remove as much air as possible from the lumen of the MOF to form negative pressure. Accurately weigh the nematicide growth promoter dissolved in deionized water to prepare a nematicide growth promoter solution, and inject the promoter into the vacuum reaction tube through the rubber stopper using a syringe. Stir magnetically for 9 hours. The mass ratio of MOF to nematicide growth promoter is 30:3.

[0054] Use a sand core funnel to filter the mixed suspension, and rinse with deionized water 5 times to wash away the free nematicide growth promoter outside. Dry the obtained MOF-nematicide growth promoter composite filter cake in a vacuum drying oven at 90℃ until the weight is constant. Grind the dried MOF-nematicide growth promoter composite with a mortar to obtain MOF-nematicide growth promoter composite powder.

[0055] The preparation method of the long-acting composite slow-release type fully biodegradable mulch film with nematicidal and growth-promoting properties includes the following steps: Weigh the MOF-nematicide growth promoter composite and poly-ε-caprolactone, and mix them uniformly at a mass ratio of 1:99 at 90℃ for 12 hours. Add the above-mentioned poly-ε-caprolactone and MOF-nematicide growth promoter composite to a twin-screw extruder. There are three consecutive temperature zones from the feeding part to the die head: 140℃, 150℃, and 160℃. The feeding rate is set to 50 g / min, and the screw rotation speed is 45 rpm. Then, the molten composite material extruded by the twin-screw extruder is cooled by the traction of the traction device, and then granulated by a pelletizer at a rotation speed of 35 rpm to obtain a composite master batch. Dry the obtained composite master batch at 90℃ for 9 hours, and then melt-extrude it in a single-screw extruder. Finally, blow it into a mulch film by a film blowing machine.

[0056] The process temperature for blowing film is set to 165 / 160 / 155 / 150 / 145℃, the screw rotation speed is 60 rpm, the drawing rate is 40 Hz, and the collection rate is 25 Hz, so that the slow-release full-biodegradable nematode-killing growth mulch film is obtained, which is packaged with black light-proof plastic bags and stored in a dry, cool, and dark place. The thickness of the slow-release full-biodegradable nematode-killing growth mulch film is controlled to be 20±1 μm.

[0057] Comparative Example The preparation method of the blank non-nematode-killing growth film comprises the following steps: The poly-ε-caprolactone is dried at 90℃ for 12 h, and then added into the twin-screw extruder; there are three continuous temperature zones from the feeding part to the die head: 170℃, 175℃, and 180℃, the feeding rate is set to 50 g / min, and the screw rotation speed is 45 rpm; then the extruded melt-state composite material of the twin-screw is cooled under the traction of the traction device, and then granulated by the granulator to obtain the composite master batch, and the rotation speed of the granulator is 35 rpm. The obtained composite master batch is dried at 90℃ for 9 h. Before blown film forming, the suitable processing temperature of the composite material is determined by using a melt index tester.

[0058] The process temperature for blowing film is set to 170 / 175 / 180 / 175 / 165℃, the screw rotation speed is 60 rpm, the drawing rate is 40 Hz, and the collection rate is 25 Hz, so that the blank non-nematode-killing film is obtained, which is packaged with black light-proof plastic bags and stored in a dry, cool, and dark place. The thickness of the blank non-nematode-killing film is controlled to be 20±1 μm.

[0059] The preparation method of the conventional non-slow-release nematode-killing growth mulch film comprises the following steps: The nematode-killing growth aid pelargonic acid octadecyl trimethyl ammonium prepared in Example 3 and poly-ε-caprolactone are directly dried at 90℃ for 12 h, and then mixed uniformly at a mass ratio of 0.09:99.91. The above-mentioned nematode-killing growth aid and poly-ε-caprolactone are added into the twin-screw extruder; there are three continuous temperature zones from the feeding part to the die head: 140℃, 150℃, and 160℃, the feeding rate is set to 50 g / min, and the screw rotation speed is 45 rpm; then the extruded melt-state composite material of the twin-screw is cooled under the traction of the traction device, and then granulated by the granulator to obtain the composite master batch, and the rotation speed of the granulator is 35 rpm. The obtained composite master batch is dried at 90℃ for 9 h. Before blown film forming, the suitable processing temperature of the composite material is determined by using a melt index tester.

[0060] The process temperature of the film blowing was set to 170 / 170 / 165 / 160 / 155℃, the screw rotation speed was 60 rpm, the pulling rate was 40 Hz, and the receiving rate was 25 Hz, so that the conventional non-release nematode-killing growth-promoting full-biodegradable mulch film was obtained, which was packaged with black opaque plastic bags and stored in a dry, cool, and light-proof place. The thickness of the conventional non-release nematode-killing growth-promoting full-biodegradable mulch film was controlled to be 20±1μm.

[0061] Experimental Example 1: Mechanical property test The blank non-nematode-killing growth-promoting film, the conventional non-release nematode-killing growth-promoting mulch film, and the release-type full-biodegradable mulch film prepared in Example 3 were taken as mulch samples, and the mechanical property test was carried out according to the standard GB / T1040.3-2006, and the results are shown in Figure 1 , in which, A is the tensile strength result graph, B is the breaking nominal strain result graph, 1 is the blank non-nematode-killing growth-promoting film, 2 is the conventional non-release nematode-killing growth-promoting mulch film, and 3 is the release-type full-biodegradable mulch film prepared in Example 3.

[0062] The results show that, compared with the blank non-nematode-killing growth-promoting film and the conventional non-release nematode-killing growth-promoting mulch film, the tensile strength and the breaking elongation of the release-type full-biodegradable mulch film prepared in Example 3 are improved, which indicates that the addition of the MOF-nematode-killing growth-promoting additive does not reduce the mechanical property of the mulch film, but rather improves the mechanical property.

[0063] Accelerated release test of nematode-killing growth-promoting mulch film in water The conventional non-release nematode-killing growth-promoting mulch film (marked as non-release mulch film), the release-type full-biodegradable mulch film prepared in Example 1 (the mass of the MOF-nematode-killing growth-promoting additive complex is 0.8% of the mass of the release-type full-biodegradable mulch film, marked as release-type full-biodegradable mulch film-0.8%), and the release-type full-biodegradable mulch film prepared in Example 3 (the mass of the MOF-nematode-killing growth-promoting additive complex is 1% of the mass of the release-type full-biodegradable mulch film, marked as release-type full-biodegradable mulch film-1%) were taken as mulch samples.

[0064] 5g of the mulch sample was accurately weighed, and the mulch sample was soaked in a 100mL ground conical flask containing 100mL of pure water, and the stopper was tightly covered. The conical flask was placed in a constant temperature air bath shaker, the temperature was set to 25℃, and the amplitude was 20mm. Every certain time, 5mL of the release liquid (i.e. the nematode-killing growth-promoting aqueous solution) was taken out with a pipette, and 5mL of pure water was added to ensure that the total volume remained unchanged. The concentration of the nematode-killing aqueous solution was detected by liquid chromatography, in which the mobile phase was acetonitrile:methanol:water=35:65:5, the detection wavelength was 220nm, the flow rate of the mobile phase was 1.0ml / min, the injection volume was 10μL, and the standard curve was drawn by configuring the standard solution. According to the peak area, the final cumulative release rate was calculated, and the results are shown in Figure 2 .

[0065] The results show that, compared with the non-buffered mulch, the addition of MOF material makes the nematode-killing growth promoter of the buffered mulch-0.8% and the buffered mulch-1% have a longer effective release period, thereby prolonging the insecticidal function period of the mulch, covering the entire growth cycle of the crop.

[0066] Experimental Example 2 The biodegradable mulch obtained in Examples 1, 2 and 3 was applied to tomato potting, and tomato potting without mulch and blank nematode-killing growth film was set as a control group. The flowerpot was 27 cm high and 26 cm in diameter. The selected tomato variety was Saint Laurent tomato, and the soil was a 1:1 mixture of nematode soil and nutrient medium.

[0067] Before planting tomato plants, the mulch was cut to the appropriate size and covered on the surface of the potting soil. Plant management referred to the experience of local farmers to ensure consistent water and fertilizer supply, and the plants were all corrected in growth by single stem training. Tomato quality was determined after harvesting, and tomato roots and rhizosphere soil were dug after fruit harvesting.

[0068] Tomato root photos: The tomato plant roots were taken, washed and photographed, as shown in Figure 3 1 was without mulch, 2 was blank nematode-killing growth film, and 3-5 were the buffered full-biodegradable mulch prepared in Examples 1-3.

[0069] The results show that, compared with the control group, the number of root nodules of the tomato roots of Examples 2 and 3 is reduced, and the number of root nodules of the tomato roots of Example 1 is the least, indicating that the mulch of Examples 1-3 has obvious effect on killing root nematodes.

[0070] Tomato root nodule index determination and calculation: After the tomato fruits were harvested, the tomato root system was taken, and the incidence of root-knot nematode disease was investigated and statistically analyzed according to the root nodules of the tomato roots. The root nodule index of the tomato was set to 10 levels: 0 level, no root nodule; 1 level, root nodules accounting for 1%~10% of the whole root system; 2 level, root nodules accounting for 11%~20% of the whole root system; 3 level, root nodules accounting for 21%~30% of the whole root system; 4 level, root nodules accounting for 31%~40% of the whole root system; 5 level, root nodules accounting for 41%~50% of the whole root system; 6 level, root nodules accounting for 51%~60% of the whole root system; 7 level, root nodules accounting for 61%~70% of the whole root system; 8 level, root nodules accounting for 71%~80% of the whole root system; 9 level, root nodules accounting for 81%~90% of the whole root system; 10 level, root nodules accounting for 91%~100% of the whole root system. The root nodule index and control effect of the mulch on the tomato plants were calculated according to the formula, including the non-mulch, blank nematode-killing film and the buffered full-biodegradable mulch prepared in Examples 1-3. 1 was non-mulch, 2 was blank nematode-killing film, and 3-5 were the buffered full-biodegradable mulch prepared in Examples 1-3.

[0071] The results are shown in Table 1: the tomato root knot index of Examples 2 and 3 is reduced, and has a certain nematocidal effect. The tomato root knot index of Example 1 is most obviously reduced, and has the best control effect.

[0072] Table 1: Effect of root-knot nematode disease prevention .

[0073] Tomato yield index determination: Tomato three fruits were taken, and after each tomato was picked, the total weight of single tomato and the number of tomatoes were recorded, and the results are shown in Table 2, 1 is no film, 2 is blank without nematocidal growth promoting film, and 3-5 is the slow-release fully biodegradable mulch prepared in Examples 1-3. A is a single fruit weight chart, B is a single tomato number chart, and C is a yield chart. Figure 4

[0074] The results show that: compared with the control group, the yield of Examples 2 and 3 is increased, and the yield of Example 1 is most obviously increased by 48.57% compared with the control, which shows that the addition of nematocidal growth promoting agent promotes crop growth and improves crop yield.

[0075] Tomato quality index determination: After the tomatoes were harvested, the soluble sugar content, organic lycopene content and Vc content of the tomatoes were determined, and the results are shown in Table 3, 1 is no film, 2 is blank without nematocidal growth promoting film, and 3-5 is the slow-release fully biodegradable mulch prepared in Examples 1-3. A is a soluble sugar chart, B is a lycopene chart, C is a vitamin C chart, and D is a soluble solid chart. Figure 5

[0076] The results show that: compared with the control group, the quality of tomatoes of Examples 2 and 3 is slightly improved, and the quality of tomatoes of Example 1 is the best, with soluble sugar increased by 61.22%, lycopene increased by 25.22%, and vitamin C content increased by 26.46%.

[0077] Determination of the number of root nematodes in the soil: After the tomato fruits were harvested, the tomato rhizosphere soil was collected by the root shaking method, 3 samples were collected for each treatment, and were put into sterile self-sealing bags and transported back to the laboratory with ice bags. The stones and plant residues were removed by passing through a 2 mm sieve, and the root-knot nematodes in the soil were separated by centrifugal flotation separation method, and the number of nematodes in the soil was detected by a stereoscopic microscope.

[0078] ​​The results are shown in Table 2: compared with the control group, the number of root-knot nematodes in the soil of Example 2 and Example 3 is reduced to a certain extent, and the number of root-knot nematodes in the soil of Example 1 is reduced more obviously, indicating that the biodegradable mulch provided by the application has a significant nematicidal effect.

[0079] .

[0080] The above only describes the preferred embodiments of the present application and is not used to limit the present application, and any equivalent replacement, modification, etc. made by those skilled in the art within the spirit and principle of the present application without any creative labor should be included in the protection scope of the present application.

Claims

1. A long-lasting composite slow-release fully biodegradable mulch film that has the functions of killing root nematodes and promoting growth, characterized in that: The mass ratio of the MOF-nematode-killing and growth-promoting agent complex to the fully biodegradable resin is 0.5-1:99-99.5; the fully biodegradable resin is one or more of polyhydroxyalkanoate, polybutylene succinate, polyε-caprolactone or polyvinyl alcohol; the nematode-killing and growth-promoting agent is the same compound, which has both the functions of killing root nematodes and promoting growth, and is one or more of choline pelargoninate, tetrabutylammonium pelargoninate, and octadecyltrimethylammonium pelargoninate.

2. The long-acting composite slow-release fully biodegradable mulch film having both the function of killing root nematodes and promoting growth according to claim 1, characterized in that: The mass ratio of the MOF-nematocidal growth-promoting agent complex to the fully biodegradable resin is 0.6-0.8:99.2-99.4; the fully biodegradable resin is polybutylene succinate; and the nematocidal growth-promoting agent is choline pelargonilate.

3. The long-acting composite slow-release fully biodegradable mulch film having the functions of killing root nematodes and promoting growth according to claim 1 or 2, characterized in that: The preparation method of the MOF-nematicide growth-promoting agent complex is: The dried MOF was placed in a vacuum reaction tube and vacuumed for 20-40 minutes; the nematicide growth-promoting additive was dissolved in deionized water to prepare an additive solution, the additive solution was added to the vacuum tube, and the MOF and the additive solution were stirred to obtain a mixed suspension; The mixed suspension is filtered and rinsed to obtain a filter cake, and the filter cake is dried to obtain a MOF-nematocidal growth-promoting agent complex; wherein the concentration of the nematocidal growth-promoting agent solution is 0.01-0.2 g / mL; and the mass ratio of the MOF to the agent is 10-50:

3.

4. The long-acting composite slow-release fully biodegradable mulch film having both the function of killing root nematodes and promoting growth according to claim 3, characterized in that: The stirring time is 5-9 hours; the rinsing is performed with deionized water for 2-6 times; and the drying temperature is 40-90°C.

5. The long-acting composite slow-release fully biodegradable mulch film having the functions of killing root nematodes and promoting growth according to claim 3, characterized in that: The preparation method of the MOF is as follows: Zinc nitrate hexahydrate, terephthalic acid, dimethylformamide and triethylamine are reacted in a reactor. After the reaction is completed, the reaction is cooled to room temperature. The solid product is centrifuged, washed and dried to obtain MOF. The ratio of zinc nitrate hexahydrate, terephthalic acid, dimethylformamide and triethylamine is 0.5-0.7:0.1-0.2:15-25:10-15; wherein the zinc nitrate hexahydrate is measured in g, the terephthalic acid is measured in g, the dimethylformamide is measured in mL, and the triethylamine is measured in mL; the reaction temperature is 130-230° C., and the reaction time is 22-30 h.

6. The long-acting composite slow-release fully biodegradable mulch film having the functions of killing root nematodes and promoting growth according to claim 5, characterized in that: The dry wipe is dried with supercritical CO2, wherein the autoclave temperature is 0-20°C and the pressure is 5-10MPa when liquid CO2 is slowly injected; When the temperature and pressure are increased to the supercritical state, the autoclave temperature is 30-50°C, the pressure is 8-20 MPa, and the maintenance time is 2-10 hours; then the pressure is released steadily and slowly at a rate of 0.1-0.5 MPa / h to allow the supercritical CO2 to be discharged from the pores non-destructively.

7. The long-acting composite slow-release fully biodegradable mulch film having the functions of killing root nematodes and promoting growth according to claim 1 or 2, characterized in that: The nematicide adjuvant is obtained by reacting tetraalkylammonium hydroxide with geranium acid and methanol, and the product is purified, filtered, rotary evaporated and dried under reduced pressure; The tetraalkylammonium hydroxide is choline hydroxide, tetrabutylammonium hydroxide, or octadecyltrimethylammonium hydroxide; the ratio of the tetraalkylammonium hydroxide, geranium acid, and methanol is 2.5-3.0:1.5-2.0:20, wherein the tetraalkylammonium hydroxide is measured in g, the geranium acid is measured in g, and the methanol is measured in mL; the reaction temperature is 20-30° C., and the reaction time is 0.5-1.5 h; the purification solvent is a mixed solvent of acetone:methanol in a ratio of 7-9:1-3; the rotary evaporation temperature is 55-65° C.; the drying temperature is 50-80° C., and the drying time is 10-30 h.

8. The method for preparing the long-acting composite slow-release fully biodegradable mulch film having the functions of killing root nematodes and promoting growth according to claim 1, characterized in that: The steps include: The MOF-nematicide growth promoter complex and fully biodegradable resin are weighed, dried at 70-100°C for 9-15 hours, mixed evenly in proportion, and the mixture is added to a twin-screw extruder; there are three continuous temperature zones from the feed part to the die head: 100-150°C, 130-180°C, and 140-190°C, the feeding rate is set to 15-60 g / min, and the screw speed is 10-50 rpm; the molten composite material extruded by the twin-screw is then cooled under the traction of a traction device, and then granulated by a pelletizer to obtain a composite masterbatch, and the pelletizer speed is 10-50 rpm; the obtained composite masterbatch is dried at 40-100°C for 5-20 hours, added to a single-screw extruder for melt extrusion, and blown into a ground film by a film blowing machine.

9. The method for preparing a long-acting composite slow-release fully biodegradable mulch film having the functions of killing root nematodes and promoting growth according to claim 7, characterized in that: The process temperature of film blowing is set to 150-180 / 145-175 / 140-170 / 135-165 / 130-160℃, the screw speed is 20-60 rpm, the traction rate is 5-50 Hz, and the collection rate is 5-30 Hz. This can produce a long-lasting composite slow-release fully biodegradable mulch film that has the effects of killing root nematodes and promoting growth, with a thickness of between 10-20μm.

10. Use of the long-acting composite slow-release fully biodegradable mulch film having the functions of killing root nematodes and promoting growth as claimed in claim 1 in tomato cultivation, characterized in that: The tomato varieties are one or more of San Laurent tomatoes, Diana tomatoes and Pink Ruyi tomatoes.

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