Biodegradable mulching film for preventing and controlling pests between rice fields and preparation method of biodegradable mulching film

Abstract

The invention relates to the field of agricultural planting, in particular to a biodegradable mulching film for preventing and controlling pests in rice fields and a preparation method of the biodegradable mulching film. The mulching film comprises a biodegradable base material, biopheromone and auxiliaries, the biopheromone is intraspecific pheromone capable of influencing the same species of organisms or interspecific pheromone capable of influencing different species of organisms, mating and breeding of pests can be influenced through the intraspecific pheromone, natural enemies of the pests can be attracted through the interspecific pheromone, and therefore the pests can be prevented and controlled. The preparation method comprises the following steps: preparing raw materials of each component; performing drying pretreatment on the raw materials and uniformly mixing the raw materials; carrying out melt blending on the mixture; and performing film blowing forming to obtain a mulching film finished product. According to the invention, the physical barrier prevention and control function of the mulching film and the biochemical regulation and control function of the biopheromone are integrated, the synergistic interaction on pests is realized, and the biopheromone can be gradually degraded along with the mulching film, so that the effects of long-acting slow release, time saving and labor saving can be achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural planting, in particular to a biodegradable mulch film for preventing and controlling pests in rice fields and a preparation method thereof. BACKGROUND

[0002] Rice field is an important grain production base in China, and its disease and pest control is crucial. Traditional plastic mulch film can keep warm and conserve soil moisture, and inhibit weeds, but it can cause serious "white pollution", and its recovery is difficult, and the residual material has a long-term negative impact on soil structure and ecological environment. As an environmentally friendly alternative product, biodegradable mulch film can be decomposed by microorganisms under natural conditions, avoiding residual pollution problems, and has been widely used. However, whether it is a traditional plastic mulch film or an existing biodegradable mulch film, its main function is concentrated in farmland microenvironment regulation (keeping warm, keeping moisture, and inhibiting weeds), and the prevention and control of pests mainly relies on its physical barrier effect (preventing some pests from pupating or emerging), and the active prevention and control ability is limited.

[0003] At present, the prevention and control methods of pests include, for example, physical and mechanical prevention and control such as light trapping and sex pheromone trapping; biological control such as attracting natural enemies (such as spiders, ladybugs, and parasitic bees); ecological control, chemical control, etc. When these methods are implemented, the related biological pheromones are usually directly and individually hung or applied to the rice field, and this implementation still has the following disadvantages: (1) short effective period, easy to be washed away by rain and lose effectiveness; (2) due to the easy early loss of effectiveness, frequent application is required, which makes the operation of rice field care complicated and costly.

[0004] Therefore, it is of important practical application value to develop a green product that combines the above physical prevention and control or biological prevention and control methods with the physical isolation of mulch film and long-lasting effectiveness. SUMMARY

[0005] The purpose of the present application is to solve the problems of the prior art, and to provide a biodegradable mulch film for preventing and controlling pests in rice fields and a preparation method thereof. By adding biological pheromones that can prevent and control pests, such as sex pheromone interferon that can interfere with the mating and reproduction of rice leaf roller or diamondback moth, and attractants that can attract natural enemies of pests, during the preparation of the biodegradable mulch film, the present application can achieve dual prevention and control of physical isolation and information pest control, greatly improve the prevention and control effect, and prolong the effectiveness of the biological pheromones after use, avoiding the need for multiple applications of biological pheromones, and realizing green and sustainable prevention and control of pests in rice fields.

[0006] In order to solve the above problems, the present application adopts the following scheme: The biodegradable mulch film for controlling pests in rice field comprises a biodegradable substrate, a biological semiochemical and an auxiliary agent; the biodegradable substrate has good biodegradability and is selected from one or more of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), polypropylene carbonate (PPC) and starch-based composite material; the biological semiochemical is intraspecific semiochemical capable of affecting the same species or interspecific semiochemical capable of affecting different species, the intraspecific semiochemical can affect the mating and reproduction of pests, and the interspecific semiochemical can attract natural enemies of pests, so as to achieve the control of pests; and the auxiliary agent is selected from one or more of plasticizers, antioxidants, light stabilizers, lubricants and fillers.

[0007] Preferably, when the biological semiochemical is intraspecific semiochemical, it is sex pheromone interfering factor capable of interfering with the mating and reproduction of Cnaphalocrocis medinalis or Chilo suppressalis.

[0008] Preferably, when the biological semiochemical is interspecific semiochemical, it is attractant slow-release carrier containing at least one attractant substance capable of attracting natural enemies of pests, and the attractant slow-release carrier is attractant microcapsule and / or attractant master batch.

[0009] Preferably, the attractant substance is a compound capable of attracting common natural enemies of pests in rice field, such as spiders, ladybugs, green lacewings and parasitic bees, and is selected from one or more of phenylacetonitrile (PAN), trans-β-farnesene (EβF), hexenol, hexenyl hexanoate and methyl salicylate.

[0010] Preferably, the attractant microcapsule is a slow-release microcapsule with a high molecular material as wall material and the attractant substance as core material, and the wall material is preferably selected from gelatin, gum arabic, urea-formaldehyde resin, polyurea or polymethyl methacrylate.

[0011] Preferably, the attractant master batch is prepared by mixing and granulating the attractant substance and a biodegradable carrier resin.

[0012] Preferably, the mass percentage of the attractant substance in the total mass of the mulch film is 0.01% to 5.0%.

[0013] The application further provides a preparation method of the biodegradable mulch film for controlling pests in rice field, comprising the following steps: Step one: preparation of raw materials of components Step two: drying treatment; Step three: melt blending; Step four: film blowing and molding.

[0014] As a preferred, when the biological semiochemical is sex pheromone disruptor, the preparation method of the biodegradable mulch for controlling pests in rice field specifically comprises the following steps: Step one: take 80-90 parts by weight of biodegradable substrate, 0.5-1 part by weight of sex pheromone disruptor, 5-10 parts by weight of plasticizer, 0.5-1 part by weight of antioxidant, and 0.5-1 part by weight of light stabilizer; Step two: put the biodegradable substrate into a vacuum oven and dry it at 80-90°C for 15-20 hours; Step three: add the dried substrate and other raw materials into a double-screw extruder, melt and mix them at 170-190°C, and then cool and cut them into granules; Step four: add the granules into a film blowing machine to blow film under the conditions of 110-130°C and a blowing ratio of 2:1-3:1, thereby obtaining the biodegradable mulch.

[0015] As a preferred, when the biological semiochemical is attractant microcapsule, the preparation method of the biodegradable mulch for controlling pests in rice field combines step three with step four, which can improve the compactness and mechanical strength of the mulch, save production energy consumption and time, and specifically comprises the following steps: Step one: take 98-99 kg of PLA and PBAT at a ratio of 3:2-3:1, 0.5-1 kg of plasticizer, and 0.5-1 kg of attractant microcapsule; Step two: put the PLA and PBAT blend into a vacuum oven and dry it at 50-80°C for 6-8 hours; Step three: mix the above materials uniformly and add them into a double-screw extruder and film blowing machine, blow mold at a processing temperature interval of 150-165°C, thereby obtaining the biodegradable mulch with a thickness of 0.007-0.009 mm.

[0016] As a preferred, the attractant microcapsule is prepared by coating the core material phenylacetonitrile (PAN) with gelatin-arabic gum as a composite wall material using complex coacervation method, and PAN microcapsule with an average particle size of 18-22 μm and a core material content of 49-51% is formed.

[0017] As a preferred, in step three, first mix the raw materials in a high-speed mixer for 10-12 minutes, and then add them into the film blowing machine to ensure uniform mixing of the materials.

[0018] When the biological semiochemical is attractant master batch, the preparation method of the biodegradable mulch for controlling pests in rice field combines step three with step four, and specifically comprises the following steps: Step one: take 95-96 kg of PBAT and PPC at a ratio of 2:1-3:1, 2-2.5 kg of attractant master batch, and 2-2.5 kg of filler; Step 2: Place the PLA and PBAT blend into a vacuum oven and dry it at 40-60℃ for 4-8 hours; Step 3: After mixing the above materials, blow mold them into a film with a thickness of 0.01-0.015mm in a twin-screw extrusion blow molding unit at a processing temperature of 140-155℃.

[0019] Preferably, the attractant masterbatch is prepared by mixing 12.5 kg of a blend of trans-β-farnesene (EβF), PLA carrier resin, and antioxidant 1010 in a ratio of 40:160:1, then mixing the mixture uniformly in an internal mixer at 50-70°C and granulating it using a twin-screw extruder. The processing temperature of the twin-screw extruder is controlled below 130°C. The resulting attractant masterbatch contains 24.5-25.5% EβF.

[0020] The beneficial effects of this invention are as follows: Functional integration and synergistic effect: This invention integrates the physical control function of mulch film (barrier and weed suppression) with the biochemical regulation function of biological pheromones (interference with mating and attraction of natural enemies), realizing the synergistic pest control of "physical + biological", which is more effective than any single technology.

[0021] Long-lasting and time-saving: The present invention integrates biopheromones into the mulch film, which allows the biopheromones to be released slowly and persistently as the mulch film gradually degrades. Its effective period can reach 2-4 months, basically covering the occurrence and damage period of major rice pests, avoiding the labor costs and inconvenience of frequent application of biopheromones.

[0022] Environmental friendliness and sustainability: In this invention, the synergistic control scheme that integrates mulch film and biopherins greatly improves the control effect on pests, thus reducing dependence on and use of chemical pesticides and reducing chemical residues. At the same time, both the mulch film and the biopherins are biodegradable materials that can naturally degrade in the soil after use, without pollution, which meets the requirements of green ecological agriculture development.

[0023] Easy and simple to use: The mulch film of this invention is used in the same way as ordinary mulch film, without changing existing agronomic practices, making it easy for farmers to accept and promote. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation method of the biodegradable mulch film of the present invention. Detailed Implementation

[0025] Example 1: The embodiment provides a biodegradable mulch film for controlling pests in a rice field, which is prepared by adding a biological information element capable of controlling pests, such as a sex pheromone disruptor capable of interfering with mating and reproduction of a rice leaf roller or a rice leaffolder, and an attractant capable of attracting natural enemies of the pests, during preparation of the biodegradable mulch film, so that physical isolation and information element pest control are achieved at the same time, the control effect is greatly improved, the biological information element is slowly released along with pollution-free degradation of the mulch film, the effectiveness of the biological information element after being put into use is prolonged, the biological information element does not need to be applied multiple times, and green and sustainable control of pests in the rice field is achieved.

[0026] The biodegradable mulch film comprises a biodegradable base material, a biological information element and an additive. The biodegradable base material has good biodegradability and is selected from one or more of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxyalkanoate (PHA), polypropylene carbonate (PPC) and a starch-based composite material. The biological information element can be an intraspecific information element capable of affecting the same species or an interspecific information element capable of affecting different species, mating and reproduction of pests are affected by the intraspecific information element, and natural enemies of the pests are attracted by the interspecific information element, so that the pests are controlled. The additive is selected from one or more of a plasticizer, an antioxidant, a light stabilizer, a lubricant and a filler.

[0027] When the biological information element is an intraspecific information element, it is specifically a sex pheromone disruptor capable of interfering with mating and reproduction of a rice leaf roller or a rice leaffolder; at this time, the biodegradable base material is polylactic acid (PLA) or polybutylene adipate terephthalate (PBAT); and the additive is a plasticizer, an antioxidant or a light stabilizer.

[0028] When the biological information element is an interspecific information element, it is specifically an attractant slow-release carrier which is uniformly dispersed in the biodegradable base material, the attractant slow-release carrier contains at least one attractant substance capable of attracting natural enemies of the pests; and the attractant slow-release carrier can be an attractant microcapsule or an attractant master batch.

[0029] When the attractant slow-release carrier is an attractant microcapsule, the biodegradable base material is a blend of PLA and PBAT; and when the attractant slow-release carrier is an attractant master batch, the biodegradable base material is a blend of PBAT and PPC.

[0030] The attractant microcapsule is a slow-release microcapsule with a high molecular material as a wall material and the attractant as a core material, and the wall material is preferably selected from gelatin, gum arabic, urea-formaldehyde resin, polyurea or polymethyl methacrylate; and the attractant master batch is prepared by mixing and granulating the attractant and a biodegradable carrier resin.

[0031] Further, the attractant is a compound capable of attracting common natural enemies in rice fields such as spiders, ladybugs, lacewings and parasitic bees, and is selected from one or more of phenylacetonitrile (PAN), trans-beta-farnesene (EβF), hexenol, hexenyl hexanoate and methyl salicylate; and the mass percentage of the attractant in the total mass of the mulch film is 0.01% to 5.0%.

[0032] The present embodiment also provides a preparation method of the biodegradable mulch film for controlling pests in rice fields, comprising the following steps: Step one: preparation of raw materials of each component Step two: drying treatment; Step three: melt blending; Step four: film blowing and forming.

[0033] Embodiment 2: The present embodiment further refines the preparation method of embodiment 1, adopts a method of interfering with the mating and reproduction of pests, and selects a sex pheromone disruptor as the semiochemical, and is mainly aimed at pests such as rice leaffolder. Therefore, the preparation method of the biodegradable mulch film specifically comprises the following steps: Step one: take 85 parts by weight of polylactic acid (PLA), 0.5 parts by weight of rice leaffolder sex pheromone disruptor, 5 parts by weight of plasticizer (tributyl citrate), 0.5 parts by weight of antioxidant (2,6-di-tert-butyl-4-methylphenol) and 0.5 parts by weight of light stabilizer (2-hydroxy-4-methoxybenzophenone); Step two: place the polylactic acid into a vacuum oven, dry at 80°C for 20 hours, remove water and impurities, and improve the stability of the polymer; Step three: add the dried polylactic acid and other raw materials into a double-screw extruder, melt mix at 170°C, and then cool and cut into granules; Step four: add the granules into a film blowing machine, blow film under the conditions of 110°C and a blowing ratio of 2:1, and prepare the biodegradable mulch film special for rice.

[0034] The mulch film prepared in the present embodiment is applied in a rice field for testing, and the results show that the population density of rice leaffolder is significantly reduced by using the mulch film added with the sex pheromone disruptor, the yield of rice is increased, and the mulch film can be gradually degraded after the rice is harvested, without obvious residual substance in the water.

[0035] Example 3 This embodiment is further refined on the basis of the preparation method of Example 1, and a method for interfering with the mating and breeding of pests is adopted, and the biological information is selected as a sex pheromone interfering factor, but it is mainly aimed at pests dominated by the diamondback moth. Therefore, the preparation method of the biodegradable mulch film specifically includes the following steps: Step one: take 90 parts by weight of polybutylene terephthalate, 0.8 parts by weight of diamondback moth sex pheromone interfering factor, 8 parts by weight of plasticizer (epoxy soybean oil), 1 part by weight of antioxidant (tris (2,4-di-tert-butylphenyl) phosphite), and 1 part by weight of light stabilizer (polymeric light stabilizer 362).

[0036] Step two: dry the polybutylene terephthalate in a vacuum oven at 90°C for 15 hours.

[0037] Step three: melt mix the dried raw materials with other additives in a double-screw extruder at 190°C, and cut into granules after cooling.

[0038] Step four: blow film in a film blowing machine at 130°C with a blow ratio of 3:1 to obtain a biodegradable mulch film special for rice.

[0039] The mulch film prepared in this embodiment is tested in a rice field, and the results show that the use of the sex pheromone interfering factor in the rice field significantly reduces the insect population density of the diamondback moth, increases the yield of rice, and the mulch film can gradually degrade after the rice is harvested, without obvious residual biological degradation of the mulch film.

[0040] Example 4 This embodiment is still refined on the basis of the preparation method of Example 1, and a method for attracting natural enemies is adopted, and the biological information is selected as an attractant microcapsule. The steps three and four in Example 1 are combined for processing, which can improve the compactness and mechanical strength of the mulch film, and also save production energy consumption and time. Specifically, the preparation method of the biodegradable mulch film includes the following steps: Step one: take 98.5 kg of PLA / PBAT (60 / 40, wt%) blend, 1 kg of plasticizer (epoxy soybean oil), and 0.5 kg of attractant microcapsule; Step two: place the PLA and PBAT blend into a vacuum oven and dry at 60°C for 7 hours; Step three: add the mixed material into a double-screw extrusion film blowing machine, and process at a temperature of 160°C to blow mold into a biodegradable mulch film with a thickness of 0.008 mm.

[0041] The attractant microcapsule is prepared by using complex coacervation method with gelatin-arabic gum as the composite wall material to coat the core material phenylacetonitrile (PAN), and forms PAN microcapsule with an average particle size of 20 μm, and the core material content is 50%.

[0042] Further, in the step three, each raw material is mixed in a high-speed mixer for 10 minutes, and then added to the film blowing machine set to ensure uniform mixing of each material.

[0043] The biodegradable mulch film prepared by the above method is immediately laid after rice transplanting, and regular investigation finds that, compared with the control plot laid with ordinary biodegradable mulch film, the number of spiders and ladybugs in the plot covered by the mulch film of the embodiment significantly increases, the population control effect on rice planthoppers is improved by more than 35%, and the use of chemical pesticides is reduced once during the whole rice growing season.

[0044] Example 5: The embodiment still further refines the preparation method of Example 1, adopts the method of attracting natural enemies, selects attractant master batch as semiochemical, and combines step three and step four in Example 1 for processing. Specifically, the preparation method of the biodegradable mulch film comprises the following steps: Step one: take PBAT / PPC (70 / 30, wt%) blend 96 kg, attractant master batch 2 kg, and filler (calcium carbonate) 2 kg; Step two: put the blend of PLA and PBAT into a vacuum oven and dry at 50°C for 6 hours; Step three: after mixing the above materials, blow them into a mulch film with a thickness of 0.01 mm through a double-screw extrusion film blowing machine set (processing temperature 150°C).

[0045] The attractant master batch is prepared by taking trans-β-farnesene (EβF) 2 kg, PLA carrier resin 8 kg, and antioxidant 1010 0.05 kg, then uniformly mixing them in a banbury mixer at 60°C, and granulating them through a double-screw extruder, wherein the processing temperature of the double-screw extruder is strictly controlled below 130°C, and the content of EβF in the obtained attractant master batch is 25%.

[0046] The biodegradable mulch film prepared by the above method is immediately laid after rice transplanting, and regular investigation finds that, compared with the control plot laid with ordinary biodegradable mulch film, the mulch film can effectively attract the natural enemy of rice leaf roller, i.e. Trichogramma chilonis, the parasitism rate of the leaf roller is significantly higher than that in the control area, and the damage rate of the leaf blade is reduced by about 30%.

Claims

1. A biodegradable mulch film for pest control in paddy fields, characterized in that, The product comprises a biodegradable substrate, biopheromones, and additives. The biodegradable substrate has good biodegradability and is selected from one or more of polylactic acid (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polyhydroxyalkanoates (PHA), polypropylene carbonate (PPC), and starch-based composite materials. The biopheromones are intraspecific pheromones that can affect organisms of the same species or interspecific pheromones that can affect organisms of different species. Intraspecific pheromones can influence the mating and reproduction of pests, while interspecific pheromones can attract natural enemies of pests, thereby achieving pest control. The additives are selected from one or more of plasticizers, antioxidants, light stabilizers, lubricants, and fillers.

2. The biodegradable mulch film for pest control in paddy fields according to claim 1, characterized in that, When the biological pheromone is an intraspecific pheromone, it is a sex pheromone interfering pheromone that can interfere with the mating and reproduction of the rice leaf roller or the rice stem borer.

3. The biodegradable mulch film for pest control in paddy fields according to claim 1, characterized in that, When the biological pheromone is an interspecific pheromone, it is an attractant slow-release carrier containing at least one attractant substance that can attract natural enemies of pests. The attractant slow-release carrier is an attractant microcapsule and / or an attractant masterbatch.

4. The biodegradable mulch film for pest control in paddy fields according to claim 3, characterized in that, The attractant is a compound that can attract common natural enemies of rice paddies, such as spiders, ladybugs, lacewings, and parasitic wasps. It is selected from one or more of phenylacetonitrile (PAN), trans-β-farnesene (EβF), hexenol, hexenyl hexanoate, and methyl salicylate.

5. The biodegradable mulch film for pest control in paddy fields according to claim 3, characterized in that, The attractant substance accounts for 0.01% to 5.0% of the total mass of the mulch film.

6. A method for preparing a biodegradable mulch film for pest control in rice paddies according to claim 2 or 3, comprising the following steps: Step 1: Preparation of raw materials for each component Step 2: Drying treatment; Step 3: Melt blending; Step 4: Film blowing and forming.

7. The preparation method according to claim 6, characterized in that, When the biopherin is a sex pheromone interferon, the preparation method of the biodegradable mulch film for pest control in rice fields specifically includes the following steps: Step 1: Take 80-90 parts by weight of biodegradable substrate, 0.5-1 parts by weight of pheromone interferon, 5-10 parts by weight of plasticizer, 0.5-1 parts by weight of antioxidant, and 0.5-1 parts by weight of light stabilizer; Step 2: Place the biodegradable substrate in a vacuum oven and dry it at 80-90℃ for 15-20 hours; Step 3: Add the dried substrate and other raw materials to a twin-screw extruder, melt and mix at 170-190℃, then cool and cut into granules; Step 4: Add the granules to the blown film machine and blow film at 110-130℃ and a blow-up ratio of 2:1-3:1 to obtain biodegradable mulch film.

8. The preparation method according to claim 6, characterized in that, When the biopherin is an attractant microcapsule, steps three and four in the preparation method are combined, and the following steps are specifically formed: Step 1: Take 98-99 kg of PLA and PBAT in a ratio of 3:2-3:1, and take 0.5-1 kg of plasticizer and 0.5-1 kg of attractant microcapsules; Step 2: Place the PLA and PBAT blend into a vacuum oven and dry it at 50-80℃ for 6-8 hours; Step 3: Mix the above materials evenly and add them to a twin-screw extrusion blown film unit. Blow mold the film at a processing temperature range of 150-165℃ to obtain a biodegradable mulch film with a thickness of 0.007-0.009mm.

9. The preparation method according to claim 8, characterized in that, The attractant microcapsules in step one are prepared by coating the core material phenylacetonitrile (PAN) with gelatin-gum arabic as the composite wall material using the complex coagulation method, forming PAN microcapsules with an average particle size of 18-22 μm and a core material content of 49-51%.

10. The preparation method according to claim 6, characterized in that, When the biological pheromone is an attractant masterbatch, steps three and four in the preparation method are combined and specifically formed into the following steps: Step 1: Take 95-96 kg of PBAT and PPC in a ratio of 2:1-3:1, and take 2-2.5 kg of attractant masterbatch and 2-2.5 kg of filler. Step 2: Place the PLA and PBAT blend into a vacuum oven and dry it at 40-60℃ for 4-8 hours; Step 3: After mixing the above materials, blow the mixture into a film with a thickness of 0.01-0.015mm using a twin-screw extrusion blown film unit at a processing temperature of 140-155℃.

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