Low-temperature-resistant defoliating agent for cotton ripening acceleration and use method of low-temperature-resistant defoliating agent
By combining low-temperature resistant defoliants with drone technology, the problem of incomplete defoliation during cotton ripening under low-temperature conditions has been solved, achieving efficient and precise cotton ripening and defoliation, and improving the quality and efficiency of cotton harvesting.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-01
- Publication Date
- 2026-03-13
AI Technical Summary
Existing defoliants for cotton ripening are less effective under low-temperature conditions in the mid-to-late stages, resulting in poor leaf-strawling effect. Furthermore, traditional methods rely on experience and are prone to missing the optimal application time, leading to incomplete defoliation, high impurity content, and reduced quality of cotton.
A low-temperature resistant defoliant is used, which contains 2% of the active ingredient pyrazosulfan, 11-23% of adjuvants and the remainder as a solvent in the form of a microemulsion, combined with emulsifiers, penetrants, stabilizers and antifreeze agents. It is applied precisely using multispectral drones and millimeter-wave radar to ensure effective ripening and defoliation in low-temperature environments.
Highly efficient cotton ripening and defoliation was achieved under low-temperature conditions, ensuring defoliation and boll opening rates, maintaining fiber quality, reducing impurities during mechanical harvesting, and improving harvesting efficiency.
Smart Images
Figure CN121647265A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of defoliant technology, and in particular to a low-temperature resistant defoliant for accelerating cotton ripening and its application method. Background Technology
[0002] Cotton is an annual or perennial herbaceous crop belonging to the Malvaceae family. Native to tropical and subtropical regions, it is now widely cultivated in warmer regions worldwide. Its growth cycle lasts approximately 5-6 months, involving sowing, budding, flowering, and boll formation. The boll naturally splits open upon maturity, revealing white fibers. Cotton fiber is an important textile raw material, possessing softness, breathability, and strong moisture absorption, accounting for over 30% of the global textile fiber market. Cottonseed can be pressed for edible oil and used to produce animal feed, while the seed hulls can be used as a culture medium. This crop has a well-developed root system and is drought- and salt-tolerant. Modern breeding techniques have led to the development of insect- and disease-resistant varieties.
[0003] Cotton ripening and defoliation is a key technology that uses chemical regulation to achieve concentrated ripening and improve harvesting efficiency. Typically, ripening agents such as ethephon are used 15-20 days before harvest to promote boll opening, while defoliants like thiamethoxam accelerate leaf shedding, allowing the plant to concentrate nutrients on the bolls. The operation requires precise control based on the accumulated temperature of the cotton field and the boll maturity level (over 70% boll opening) to avoid premature application, which could lead to decreased fiber strength or yield reduction. Drone spraying technology is now widespread, achieving uniform spray coverage, a defoliation rate of over 90%, and reducing contamination during mechanical harvesting.
[0004] Based on existing technology, it has been found that conventional defoliants commonly used in current machine-harvested cotton ripening and defoliation operations exhibit severe temperature dependence (requiring temperatures above 12℃). Their effectiveness decreases sharply under low-temperature conditions in the mid-to-late stages, resulting in poor leaf-strawling effect, incomplete defoliation, high impurity content, and reduced quality. Furthermore, delaying application to ensure yield further exacerbates the negative effects of low temperatures. Traditional cotton ripening and defoliation operations rely on experience-based judgment, easily missing the optimal application time. Therefore, this invention proposes a low-temperature resistant defoliant for cotton ripening and its application method to solve the problems existing in the prior art. Summary of the Invention
[0005] To address the aforementioned problems, the present invention aims to provide a low-temperature resistant defoliant for cotton ripening and its application method, thereby solving the problems that existing cotton ripening defoliants have significantly reduced effectiveness under low-temperature conditions in the middle and late stages, resulting in poor leaf-strawling effect, and that traditional cotton ripening and defoliation operations rely on experience-based judgment, easily missing the optimal application time.
[0006] To achieve the objective of this invention, the invention is implemented through the following technical solution: a low-temperature resistant defoliant for cotton ripening, comprising 2% active ingredient, 11-23% adjuvants, and the remainder being solvent, wherein the active ingredient is pyrazosulfan, the adjuvants are composed of emulsifier, penetrant, stabilizer and antifreeze in a mass percentage ratio of 5-10%: 2-5%: 1-3%: 3-5%, and the solvent is deionized water.
[0007] A further improvement is that the formulation of the low-temperature resistant defoliant is a microemulsion with a pH range of 6.0 to 8.0.
[0008] A further improvement is that the emulsifier is selected from one or more of alkylphenol polyoxyethylene ether, phenethylphenol polyoxyethylene polyoxypropylene ether, and castor oil polyoxyethylene ether.
[0009] A further improvement is that the penetrant is selected from fatty alcohol polyoxyethylene ether and isomeric tridecyl alcohol ether, the stabilizer is selected from epoxidized soybean oil and alkyl polysaccharide glycoside, and the antifreeze is selected from urea and glycerol.
[0010] A further improvement is made in the following specific preparation steps of the low-temperature resistant defoliant: imidacloprid and adjuvants are emulsified under constant temperature shearing to form a premixed liquid, which is then circulated through a high-pressure homogenizer. Finally, a solvent is added to the premixed liquid and mixed evenly to obtain the low-temperature resistant defoliant.
[0011] A method for using a low-temperature resistant defoliant for accelerating cotton ripening includes the following steps:
[0012] Step 1: Use a multispectral drone to scan the NDVI value of the cotton field. Apply pesticide when the NDVI value drops to 0.55-0.62.
[0013] Step 2: The critical environmental conditions for pesticide application must meet the following conditions: daily minimum temperature ≥ 7℃, real-time field temperature between 10 and 28℃ during application, and no rainfall within 72 hours after application.
[0014] Step 3: Use agricultural drones for aerial spraying. Dilute the low-temperature resistant defoliant at a dosage of 250 mL per acre, and control the final spray volume per acre of cotton field to between 1.5 and 2.0 L.
[0015] Step 4: Equip the plant protection drone with millimeter-wave radar and dynamically adjust the flight altitude at 1.5-2.0m above the cotton canopy. Control the flight speed at 5-6m / s and adjust the spray spacing according to the drone type and wind conditions to spray pesticides and achieve the application of low-temperature resistant defoliant.
[0016] A further improvement is made in step two, where re-spraying is performed if rain occurs within 72 hours of initial application. The re-spraying strategy is as follows:
[0017] Rainfall ≥ 5mm and > 1 hour: Re-spray 50% of the original amount within 24 hours after the rain stops;
[0018] Rainfall of 2-5 mm and less than 1 hour: Re-spray 30% of the original amount;
[0019] When applying additional spray, the average daily temperature should be ≥10℃.
[0020] A further improvement is made in step three, in which polyether-modified trisiloxane is added when preparing the mother liquor, and the amount of polyether-modified trisiloxane added is 0.05 to 0.1% of the total amount of the mother liquor.
[0021] The beneficial effects of this invention are as follows: The defoliant of this invention adopts a specific microemulsion formulation and compound adjuvant system, which enhances the permeability and environmental stability of the liquid. It can rapidly induce physiological metabolic disorders in leaves under low temperature conditions, simultaneously accelerate the cracking of cotton bolls and the formation of petiole abscission layer, and achieve a dynamic balance of the triple effects of blanching, ripening and defoliation. Combined with intelligent application decision-making based on multispectral remote sensing and millimeter-wave radar, it accurately identifies the maturity of cotton fields and dynamically adjusts operation parameters, effectively overcoming the problems of incomplete defoliation and asynchronous boll opening caused by climate fluctuations in traditional methods. While ensuring a high defoliation rate and concentrated boll opening, it maintains the mechanical properties and quality uniformity of cotton fibers, reduces the proportion of post-frost flowers and the content of impurities during mechanical harvesting, and significantly improves the comprehensive efficiency of cotton ripening and defoliation under low temperature conditions. Attached Figure Description
[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0023] Figure 1 This is a schematic diagram of the application method of the low-temperature resistant defoliant for cotton ripening according to the present invention. Detailed Implementation
[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0025] As one of the world's most important economic crops, cotton's production process is increasingly mechanized, which is a key trend for improving efficiency and reducing costs. Mechanized cotton harvesting technology is a core manifestation of this trend. However, mechanized cotton harvesting places specific requirements on the agronomic traits of cotton, the most crucial of which is that the cotton plants must undergo sufficient defoliation and ripening before harvest. Excessive leaves increase the impurity content of the harvested seed cotton, such as leaf debris and green stains, severely reducing the quality and grade of the lint; simultaneously, unopened bolls cannot be harvested, directly leading to yield loss. Therefore, efficient and reliable chemical defoliation and ripening technology has become an indispensable part of mechanized cotton harvesting. Traditional defoliants (such as a combination of thiamethoxam and diuron) are highly dependent on consistently high ambient temperatures (usually requiring a daily average temperature above 18-20°C). This is sufficient in the early stages of the harvest season when temperatures drop sharply, but as production generally delays application to pursue higher yields, low-temperature applicability has become a technical bottleneck restricting defoliation effectiveness and ultimate profitability.
[0026] NDVI (Normalized Difference Vegetation Index) is a vegetation cover index calculated using the difference in reflectance between the near-infrared and red light bands in remote sensing technology. Its value ranges from -1 to 1. In agriculture, NDVI reflects crop growth status, chlorophyll content, and biomass; a higher value indicates denser and healthier vegetation. In cotton defoliation technology, when the NDVI value drops to a specific threshold (e.g., 0.55–0.62), it indicates reduced photosynthesis and physiological maturity in the cotton plant. Applying pesticides at this time allows for precise matching to the plant's metabolic transition period, ensuring the defoliant works efficiently.
[0027] Example 1
[0028] This embodiment provides a low-temperature resistant defoliant for cotton ripening. The low-temperature resistant defoliant is composed of 2% active ingredient, 11% adjuvants and 87% solvent by mass percentage. The active ingredient is pyrazosulfuron, and the adjuvants are composed of emulsifier, penetrant, stabilizer and antifreeze agent in a mass percentage ratio of 5%:2%:1%:3%. The solvent is deionized water.
[0029] The low-temperature resistant defoliant of this embodiment is a microemulsion, which is a semi-transparent homogeneous liquid with a pH of 6.0. It has a stability of ≥2 years under normal temperature storage conditions, a microemulsion particle size distribution D90≤50nm, no stratification in centrifugal stability test (4000r / min, 30min), and an effective ingredient decomposition rate of <5% after low temperature (0℃) and heat storage (54±2℃) tests.
[0030] This low-temperature resistant defoliant achieves highly efficient ripening and defoliation in low-temperature environments through a scientifically formulated ratio. The core component, pyrazosulfuron, serves as the active ingredient, balancing efficacy and environmental safety. It is specifically designed to address low-temperature boll ripening obstacles, while the adjuvant system constructs a multi-layered synergistic mechanism.
[0031] Emulsifiers form stable microemulsion interfaces, ensuring uniform dispersion of the agent in low-temperature water.
[0032] Penetrants enhance the ability of the cuticle to penetrate, overcoming plant epidermal resistance caused by low temperatures;
[0033] Stabilizers maintain the molecular integrity of chemical components during storage and at extreme temperatures;
[0034] Antifreeze agents ensure the fluidity of the drug solution by inhibiting its freezing point;
[0035] Using deionized water as the main solvent reduces costs while minimizing the risk of organic pollution.
[0036] The preparation process of the low-temperature resistant defoliant in this embodiment includes the following steps:
[0037] S1. Pyrazosulfan and adjuvants are subjected to isothermal shear emulsification at 40°C with a shear rate ≥8000rpm for 20min to form a premix.
[0038] S2. The premixed liquid is then circulated three times by a high-pressure homogenizer at a homogenization pressure of 150 bar.
[0039] S3. Then add solvent to the homogenized premixed liquid and mix evenly to obtain the low-temperature resistant defoliant product.
[0040] In this embodiment, the emulsifier is alkylphenol polyoxyethylene ether;
[0041] The penetrant is fatty alcohol polyoxyethylene ether;
[0042] The stabilizer is epoxidized soybean oil;
[0043] The antifreeze is urea.
[0044] The low-temperature resistant defoliant of this embodiment inhibits protoporphyrinogen oxidase in cotton plants, resulting in a protoporphyrin accumulation of 2.3 μmol / g·FW in the leaves. This disrupts the mesophyll cell membrane structure, thereby inducing a peak ethylene release rate of 4.8 nL / g·h and an abscisic acid content of 35 ng / g in the leaves. This induces a stress effect in the cotton plants, significantly increasing the biosynthesis levels of endogenous ethylene and abscisic acid. The high content of ethylene and abscisic acid promotes boll opening and leaf shedding, thus achieving a triple effect of killing green, ripening cotton bolls, and promoting the formation of the petiole abscission layer.
[0045] See Figure 1This embodiment also provides a method for using a low-temperature resistant defoliant for cotton ripening, including the following steps:
[0046] Step 1: Decision on Drug Administration
[0047] Multispectral drones were used to scan the NDVI value of cotton fields. When the NDVI dropped to 0.55, the pesticide was applied. The corresponding application time was when the natural boll opening rate of cotton plants reached 30%, and the top cotton bolls were basically formed but not fully cracked. This timing was 7 days later than the conventional defoliation time when using the traditional 54% thiamethoxam·diuron defoliant.
[0048] Step 2: Environmental Control
[0049] The critical environmental conditions that must be met during pesticide application are:
[0050] The daily minimum temperature is ≥7℃, and the real-time field temperature is between 10℃ and 28℃ during pesticide application.
[0051] If there is no rainfall within 72 hours after application, and rainfall occurs within 72 hours, a second spray should be applied. The second spraying strategy is as follows:
[0052] Rainfall ≥ 5mm and > 1 hour: Re-spray 50% of the original spray amount within 24 hours after the rain stops;
[0053] Rainfall of 2-5 mm and less than 1 hour: Re-spray with 30% of the original spray amount;
[0054] When applying additional spray, the average daily temperature should be ≥10℃.
[0055] Step 3: Preparation of the medicine
[0056] Aerial spraying was carried out using agricultural drones. The defoliant was diluted at a dosage of 250 mL per acre using a two-stage dilution method. First, a stock solution was prepared in the mixing tank, and 0.05% polyether-modified trisiloxane was added to bring the surface tension of the solution to 28 mN / m to enhance the defoliation effect. Then, the diluted solution was transferred to the drone's tank and water was added. Finally, the amount of spray solution per acre was controlled to be between 1.5 L.
[0057] Step 4: Aerial spraying operation
[0058] Aerial spraying operations are carried out using plant protection drones equipped with millimeter-wave radar. The flight altitude is dynamically adjusted at 1.5 to 2.0 meters above the cotton canopy, and the flight speed is controlled at 5 m / s. The spray spacing is adjusted according to the type of drone and wind conditions to ensure that the atomized particle size is 150±50 μm, so as to achieve comprehensive and uniform coverage of the upper and middle leaves of the cotton plant by the pesticide solution.
[0059] The method for using a low-temperature resistant defoliant for accelerating cotton ripening provided in this embodiment is particularly suitable for the following specific agronomic scenarios:
[0060] a) Cotton fields that voluntarily postpone defoliation by 7 to 15 days in pursuit of higher yields;
[0061] b) Cotton fields planted with herb-resistant cotton varieties that are late-maturing and have a long growing season;
[0062] c) Cotton fields that have already used conventional defoliants but whose ripening and defoliation effects were poor due to low temperatures, requiring remedial spraying.
[0063] The method of using a low-temperature resistant defoliant for cotton ripening provided in this embodiment demonstrates the following effects on cotton ripening and defoliation:
[0064] Leaves turn chlorotic and wither within 24 hours of application;
[0065] Cotton bolls crack and delamination occur rapidly within 3 days.
[0066] 7-day leaf shedding rate ≥90%, boll opening rate ≥95%;
[0067] Fiber breaking strength ≥30cN / tex, micronaire value 3.7, pre-frost flower ratio ≥98%;
[0068] Seven days after application, the leaf defoliation rate reached over 90%, and the boll opening rate exceeded 95%, meeting the agronomic requirements for mechanized cotton harvesting.
[0069] Example 2
[0070] This embodiment provides a low-temperature resistant defoliant for cotton ripening. The low-temperature resistant defoliant is composed of 2% active ingredient, 23% adjuvants and 75% solvent by mass percentage. The active ingredient is pyrazosulfuron, and the adjuvants are composed of emulsifier, penetrant, stabilizer and antifreeze in a mass percentage ratio of 10%:5%:3%:5%. The solvent is deionized water.
[0071] The low-temperature resistant defoliant of this embodiment is a microemulsion, which is a semi-transparent homogeneous liquid with a pH of 8.0. It has a stability of ≥2 years under normal temperature storage conditions, a microemulsion particle size distribution D90≤50nm, no stratification in centrifugal stability test (4000r / min, 30min), and an effective ingredient decomposition rate of <5% after low temperature (0℃) and heat storage (54±2℃) tests.
[0072] This low-temperature resistant defoliant achieves highly efficient ripening and defoliation in low-temperature environments through a scientifically formulated ratio. The core component, pyrazosulfuron, serves as the active ingredient, balancing efficacy and environmental safety. It is specifically designed to address low-temperature boll ripening obstacles, while the adjuvant system constructs a multi-layered synergistic mechanism.
[0073] Emulsifiers form stable microemulsion interfaces, ensuring uniform dispersion of the agent in low-temperature water.
[0074] Penetrants enhance the ability of the cuticle to penetrate, overcoming plant epidermal resistance caused by low temperatures;
[0075] Stabilizers maintain the molecular integrity of chemical components during storage and at extreme temperatures;
[0076] Antifreeze agents ensure the fluidity of the drug solution by inhibiting its freezing point;
[0077] Using deionized water as the main solvent reduces costs while minimizing the risk of organic pollution.
[0078] The preparation process of the low-temperature resistant defoliant in this embodiment includes the following steps:
[0079] S1. Pyrazosulfan and adjuvants are subjected to isothermal shear emulsification at 45°C with a shear rate ≥8000rpm for 30min to form a premix.
[0080] S2. The premixed liquid is then circulated three times by a high-pressure homogenizer at a homogenization pressure of 200 bar.
[0081] S3. Then add solvent to the homogenized premixed liquid and mix evenly to obtain the low-temperature resistant defoliant product.
[0082] In this embodiment, the emulsifier is a compound of phenylethylphenol polyoxyethylene polyoxypropylene ether and castor oil polyoxyethylene ether in a mass ratio of 3:1.
[0083] The penetrant is isomeric tridecyl alcohol ether;
[0084] The stabilizer is an alkyl polysaccharide glycoside;
[0085] The antifreeze is glycerol.
[0086] The low-temperature resistant defoliant of this embodiment inhibits protoporphyrinogen oxidase in cotton plants, resulting in a protoporphyrin accumulation of 3.5 μmol / g·FW in the leaves. This disrupts the mesophyll cell membrane structure, thereby inducing a peak ethylene release rate of 5.6 nL / g·h and an abscisic acid content of 42 ng / g in the leaves. This induces a stress effect in the cotton plants, significantly increasing the biosynthesis levels of endogenous ethylene and abscisic acid. The high content of ethylene and abscisic acid promotes boll opening and leaf shedding, thus achieving a triple effect of killing green, ripening cotton bolls, and promoting the formation of the petiole abscission layer.
[0087] See Figure 1 This embodiment also provides a method for using a low-temperature resistant defoliant for cotton ripening, including the following steps:
[0088] Step 1: Decision on Drug Administration
[0089] Multispectral drones were used to scan the NDVI value of cotton fields. When the NDVI dropped to 0.62, the pesticide was applied. The corresponding application time was when the cotton plants had a natural boll opening rate of 40% and the top cotton bolls had basically formed but had not fully cracked. This timing was 15 days later than the conventional defoliation time when using the traditional 54% thiamethoxam·diuron defoliant.
[0090] Step 2: Environmental Control
[0091] The critical environmental conditions that must be met during pesticide application are:
[0092] The daily minimum temperature is ≥7℃, and the real-time field temperature is between 10℃ and 28℃ during pesticide application.
[0093] If there is no rainfall within 72 hours after application, and rainfall occurs within 72 hours, a second spray should be applied. The second spraying strategy is as follows:
[0094] Rainfall ≥ 5mm and > 1 hour: Re-spray 50% of the original spray amount within 24 hours after the rain stops;
[0095] Rainfall of 2-5 mm and less than 1 hour: Re-spray with 30% of the original spray amount;
[0096] When applying additional spray, the average daily temperature should be ≥10℃.
[0097] Step 3: Preparation of the medicine
[0098] Aerial spraying was carried out using agricultural drones. The defoliant was diluted at a dosage of 250 mL per acre using a two-stage dilution method. First, a stock solution was prepared in the mixing tank, and 0.1% of the total stock solution was added with polyether-modified trisiloxane to bring the surface tension of the solution to 32 mN / m, which enhanced the defoliation effect. Then, the diluted solution was transferred to the drone's tank and water was added. Finally, the amount of spray solution per acre was controlled to be between 2.0 L.
[0099] Step 4: Aerial spraying operation
[0100] Aerial spraying operations are carried out using plant protection drones equipped with millimeter-wave radar. The flight altitude is dynamically adjusted at 1.5 to 2.0 meters above the cotton canopy, and the flight speed is controlled at 6 m / s. The spray spacing is adjusted according to the type of drone and wind conditions to ensure that the atomized particle size is 150±50 μm, so as to achieve comprehensive and uniform coverage of the upper and middle leaves of the cotton plant by the pesticide solution.
[0101] The method for using a low-temperature resistant defoliant for accelerating cotton ripening provided in this embodiment is particularly suitable for the following specific agronomic scenarios:
[0102] a) Cotton fields that voluntarily postpone defoliation by 15 days in pursuit of higher yields;
[0103] b) Cotton fields planted with herb-resistant cotton varieties that are late-maturing and have a long growing season;
[0104] c) Cotton fields that have already used conventional defoliants but whose ripening and defoliation effects were poor due to low temperatures, requiring remedial spraying.
[0105] The method of using a low-temperature resistant defoliant for cotton ripening provided in this embodiment demonstrates the following effects on cotton ripening and defoliation:
[0106] Leaves turn chlorotic and wither within 24 hours of application;
[0107] Cotton bolls crack and delamination occur rapidly within 5 days;
[0108] Leaf shedding rate ≥90% and boll opening rate ≥95% after 10 days;
[0109] Fiber breaking strength ≥30cN / tex, micronaire value 4.2, pre-frost flower ratio ≥98%;
[0110] Ten days after application, the leaf defoliation rate reached over 90%, and the boll opening rate exceeded 95%, meeting the agronomic requirements for mechanized cotton harvesting.
[0111] The results of comparing the commercially available conventional ripening and defoliating agent 54% thiabendazole with the low-temperature resistant defoliating agent of this invention are shown in Table 1 below:
[0112] Table 1 Comparison of pesticide application
[0113]
[0114] As can be seen from Table 1 above, the low-temperature resistant defoliant of the present invention has a significantly better ripening and defoliation effect than traditional defoliants.
[0115] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A low-temperature resistant defoliant for accelerating cotton ripening, characterized in that: It comprises 2% active ingredient, 11-23% adjuvants, and the balance being solvent. The active ingredient is pyrazosulfan. The adjuvants are composed of emulsifier, penetrant, stabilizer and antifreeze in a mass percentage ratio of 5-10%: 2-5%: 1-3%: 3-5%. The solvent is deionized water.
2. The low-temperature resistant defoliant for cotton ripening according to claim 1, characterized in that: The low-temperature resistant defoliant is formulated as a microemulsion with a pH range of 6.0 to 8.
0.
3. The low-temperature resistant defoliant for cotton ripening according to claim 1, characterized in that: The emulsifier is selected from one or more of alkylphenol polyoxyethylene ether, phenethylphenol polyoxyethylene polyoxypropylene ether, and castor oil polyoxyethylene ether.
4. The low-temperature resistant defoliant for cotton ripening according to claim 1, characterized in that: The penetrant is selected from fatty alcohol polyoxyethylene ether and isotridecyl alcohol ether; the stabilizer is selected from epoxidized soybean oil and alkyl polysaccharide glycoside; and the antifreeze is selected from urea and glycerol.
5. A low-temperature resistant defoliant for cotton ripening according to claim 1, characterized in that: The specific preparation steps of the low-temperature resistant defoliant are as follows: imidacloprid and adjuvants are emulsified under constant temperature shearing to form a premixed liquid, which is then circulated through a high-pressure homogenizer. Finally, a solvent is added to the premixed liquid and mixed evenly to obtain the low-temperature resistant defoliant.
6. A method of using a low-temperature resistant defoliant for cotton ripening as described in any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Use a multispectral drone to scan the NDVI value of the cotton field. Apply pesticide when the NDVI value drops to 0.55-0.
62. Step 2: The critical environmental conditions for pesticide application must meet the following conditions: daily minimum temperature ≥ 7℃, real-time field temperature between 10 and 28℃ during application, and no rainfall within 72 hours after application. Step 3: Use agricultural drones for aerial spraying. Dilute the low-temperature resistant defoliant at a dosage of 250 mL per acre, and control the final spray volume per acre of cotton field to between 1.5 and 2.0 L. Step 4: Equip the plant protection drone with millimeter-wave radar and dynamically adjust the flight altitude at 1.5-2.0m above the cotton canopy. Control the flight speed at 5-6m / s and adjust the spray spacing according to the drone type and wind conditions to spray pesticides and achieve the application of low-temperature resistant defoliant.
7. The method of using a low-temperature resistant defoliant for cotton ripening according to claim 6, characterized in that: In step two, if rain occurs within 72 hours after the initial application, a second spray should be performed. The second spraying strategy is as follows: Rainfall ≥ 5mm and > 1 hour: Re-spray 50% of the original amount within 24 hours after the rain stops; Rainfall of 2-5 mm and less than 1 hour: Re-spray 30% of the original amount; When applying additional spray, the average daily temperature should be ≥10℃.
8. The method of using a low-temperature resistant defoliant for cotton ripening according to claim 6, characterized in that: In step three, polyether-modified trisiloxane is added when preparing the mother liquor, and the amount of polyether-modified trisiloxane added is 0.05 to 0.1% of the total amount of the mother liquor.