Method for efficiently and safely weeding in tropical upland rice field

Abstract

The invention discloses an efficient and safe weeding method for a tropical upland rice field, and belongs to the technical field of agricultural planting. The method comprises the following steps: spraying glufosinate-ammonium to kill germinated weeds 10-15 days before sowing; (after sowing and before emergence of seedlings, spraying butachlor and bensulfuron methyl to form a pre-emergence closed pesticide film; 15-20 days after seedling emergence, spraying a compound preparation of quinclorac and pyrazosulfuron-ethyl in a ratio of 1: 1 and a compound preparation of MCPA and fluroxypyr in a ratio of 1: 1; 30-35 days after seedling emergence, a cyhalofop-butyl / haloxysulfuron-methyl and penoxsulam compound agent is sequentially applied, and brassinolide and monopotassium phosphate are sprayed 3 days after secondary pesticide application; supplementing and preventing in the middle and later tillering periods, and spraying naphthylacetic acid, urea and monopotassium phosphate 3 days after weeding. The water adding amount in each stage is dynamically adjusted according to the soil water content, the method is suitable for the tropical upland rice area with the annual average temperature larger than or equal to 25 DEG C, the annual rainfall larger than or equal to 1500 mm and the humidity larger than or equal to 80%, and through five-stage time sequence cooperation and precise intervention of the conditioning agent, the weed control effect larger than or equal to 95.2% is achieved, and the phytotoxicity grade is 0 grade.

Description

Technical Field

[0001] This invention belongs to the field of agricultural planting technology, and specifically relates to a method for efficient and safe weed control in tropical upland rice fields. Background Technology

[0002] With the continuous optimization of tropical agricultural planting models, upland rice (dryland rice) is gaining increasing attention in hot and humid regions such as Hainan and Yunnan due to its water-saving, barren-tolerant, and adaptable characteristics to fallow land. As a drought-tolerant ecological type of rice, upland rice cultivation systems have broken free from the dependence on irrigation in traditional paddy fields. However, in tropical environments with an average annual temperature above 25℃, annual rainfall exceeding 1500 mm, and air humidity consistently above 80%, noxious weeds such as crabgrass, goosegrass, Echinochloa crus-galli, and Eclipta prostrata germinate rapidly and exhibit strong herbicide resistance, severely restricting the yield and quality of upland rice. This makes efficient and safe weed control a technical bottleneck for this planting system.

[0003] Many existing weed control strategies rely heavily on paddy field experience, neglecting the significant differences in soil moisture dynamics and herbicide behavior between dryland and paddy fields. For example, current technologies using a combination of cyhalofop-butyl with pyrimethanil or chlorpyrifos, while performing well under flooded conditions, can lead to excessively high localized herbicide concentrations in dryland paddy fields due to insufficient leaching, inducing leaf burn and even plant death. Two-stage treatments using glufosinate and cyhalofop-butyl have also been attempted, but the control efficacy is only 80%-85%, and there is a lack of pre-emergence control and refined supplemental control mechanisms during the tillering stage, making it difficult to cover the entire germination window of weeds.

[0004] Existing technologies are further constrained by industry biases, generally avoiding the synergistic application of plant growth regulators and foliar fertilizers. Current standards prohibit the use of regulators during weed control, arguing that they may interfere with herbicide absorption; while academic research has verified the restorative effects of naphthaleneacetic acid (NAA) and urea on crops such as corn, it suggests that they are unsuitable for rice crops because urea easily causes leaf burn. Although there have been attempts to combine brassinolide with herbicides, the actual effects have been limited, failing to resolve the fundamental contradiction of balancing herbicide damage and control efficacy under high temperature and humidity conditions.

[0005] Therefore, there is an urgent need for an integrated weeding method that is adapted to the dryland ecology of tropical upland rice, integrates precise application of herbicides across multiple growth stages, herbicide rotation and regulator synergy, in order to achieve a technological breakthrough with high weed control efficacy and zero herbicide damage. Summary of the Invention

[0006] The purpose of this invention is to provide a method for efficient and safe weed control in tropical upland rice fields, overcoming the shortcomings of existing technologies such as insufficient control efficacy, high risk of herbicide damage, and inhibited growth under high temperature, high humidity, and dry conditions, achieving weed control efficacy ≥95%, herbicide damage level 0, and a significant increase in the number of effective tillers.

[0007] To achieve the above-mentioned objectives, the technical solution adopted by this invention is as follows: This invention provides a method for efficient and safe weed control in tropical upland rice fields, the method comprising the following five stages performed sequentially: (1) Weed control before sowing: 10 to 15 days before sowing, spray 200-250 ml / mu of 20% glufosinate-ammonium aqueous solution, diluted with 30-45 kg of water, to kill the weeds that have already sprouted. (2) Pre-emergence herbicide application: After sowing and before the emergence of upland rice seedlings, spray 100-120 g / mu of 60% butachlor and 60-70 g / mu of bensulfuron-methyl after the soil surface is moistened and naturally dried, and dilute with 30-45 kg of water to form a pre-emergence herbicide film. (3) Seedling stage weeding: 15 to 20 days after the emergence of upland rice, spray 40-50 g / mu of 1:1 compound preparation of dichloroquinoline acid and pyrimisulfuron and 60-75 ml / mu of 1:1 compound preparation of 2,4-D and clopyralid, diluted with 30-45 kg of water for targeted weeding during the seedling stage. (4) Weeding in the early tillering stage: 30 to 35 days after the emergence of upland rice seedlings, weeding should be carried out in sequence as follows: a) Spray 35-40 ml / mu of cyhalofop-butyl and 22-25 g / mu of chlorpyrifos, diluted with 45 kg of water; b) Ten days after application in a), spray 80-90 ml / mu of a compound formulation containing 2.5%-5% penoxsulam and 10%-15% cyhalofop-butyl, along with 40-50 ml / mu of 2.5% penoxsulam single agent, diluted with 45 kg of water. c) Three days after b), spray with 3-5 ml / mu of 0.01% brassinolide and 20-25 g / mu of potassium dihydrogen phosphate, diluted in 45 kg of water. (5) Mid-to-late tillering control: If noxious weeds still exist in the field 40 to 55 days after the emergence of upland rice seedlings, then: a) Spray 60-80 g / mu of a 1:1 mixture of dichloroquinoline acid and pyrimisulfuron, and 80-100 ml / mu of a 1:1 mixture of 2,4-D and clopyralid, diluted with 45 kg of water. b) Three days after application of the pesticide in a), spray with 20-25 ml / mu of 0.2% naphthaleneacetic acid, 25-30 g / mu of potassium dihydrogen phosphate and 600-800 g / mu of urea, diluted with 45 kg of water. The amount of water added in steps (1), (2), and (3) is dynamically adjusted according to the soil moisture content: 45 kg / mu when the soil moisture content is below 15%, 30 kg / mu when it is above 25%, and 35-45 kg / mu when the soil moisture content is between 15% and 25%. The method is applicable to tropical upland rice planting areas with an average annual temperature of 25-30℃, an annual rainfall of 1500-2000 mm, and an air humidity of 80%-90%.

[0008] Furthermore, in step (1), the field is kept free of standing water from the time of application until sowing, and the application is carried out in a clear and windless weather. A fan-shaped atomizing nozzle is used, with a working pressure of 0.2-0.3 MPa and a droplet size of 200-300 micrometers.

[0009] Furthermore, in step (2), the surface soil is moistened to bring the water content of the 0-5 cm soil layer to 60%-70% of the field capacity, and then allowed to dry naturally for 12-24 hours to make the surface soil slightly dry and not compacted. The spray droplets have a particle size of 300-400 micrometers to form a stable pesticide film layer on the soil surface.

[0010] Furthermore, in step (3), directional spraying technology is used, with the spray bar 30-40 cm above the ground and a walking speed of 0.8-1.2 m / s, avoiding the heart leaves of upland rice to ensure that the pesticide accurately covers the stems and leaves of weeds.

[0011] Furthermore, the soil moisture content was measured on-site using a portable time domain reflectometer (TDR) to guide the dynamic adjustment of the water dilution amount.

[0012] Furthermore, the method has a comprehensive control efficacy of no less than 95% against crabgrass, goosegrass, Echinochloa crus-galli, and Eclipta prostrata, and the herbicide damage level of upland rice is 0.

[0013] Compared with the prior art, the present invention has the following significant advantages: (1) Significantly improved weed control efficacy: Through five-stage relay rotation application, covering the germination window of the entire growth period of weeds, the comprehensive control efficacy against tropical malignant weeds such as crabgrass, goosegrass and edelweiss is no less than 95%, effectively overcoming the problem of insufficient control efficacy caused by the lack of pre-bud sealing and fine supplementary control during the tillering stage in existing technologies.

[0014] (2) Crop safety is greatly improved: Brassinolide, naphthaleneacetic acid and foliar fertilizer are precisely introduced on the 3rd day after the herbicide is applied, which effectively alleviates the herbicide stress. Field trials show that the herbicide damage level of upland rice is 0, which effectively solves the technical problems of frequent herbicide damage and inhibited tillering in the existing herbicide strategy.

[0015] (3) Stable and improved yield: The synergistic effect of regulators and nutrients not only did not inhibit growth, but also promoted the increase of effective tiller number (up to 8.7-9.1 plants / hole), ultimately achieving a yield of 385-402 kg per mu, which is more than 30.5% higher than the traditional model.

[0016] (4) Strong environmental adaptability: The soil moisture content is measured by a portable TDR, the amount of water added is dynamically adjusted (30-45 kg / mu), and the droplet size and application parameters are matched to ensure that the weeding effect and safety can be maintained under different tropical moisture conditions such as drought, suitable moisture and humidity.

[0017] In summary, this invention successfully solves the three major problems of "insufficient efficacy", "high risk of herbicide damage" and "ignoring soil moisture dynamics" under the dryland conditions of tropical upland rice, and provides an efficient, safe, stable-yield and scalable integrated weed control method. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of this invention, the present application will be further described in detail below with reference to embodiments.

[0019] All examples and comparative examples were conducted in Yongling Village, Yongfa Town, Chengmai County, Hainan Province (experimental base of Hainan Academy of Agricultural Sciences, with an average annual temperature of 26.8℃, annual rainfall of 1850 mm, and air humidity of 82%). The tested upland rice variety was "Shanlanlu No. 1," the soil type was lateritic red soil, pH 5.2, and organic matter content was 1.8%. The weed community was dominated by crabgrass (Digitaria sanguinalis). Bloody fingernail ), goosegrass ( Eleusis is in the east. ),, Qianjinzi ( Leptochloa chinensis ) and snake intestines ( Prostrate Eclipta The main components were phytochemicals, accounting for 40%, 25%, 18%, and 12% respectively, with other weeds accounting for 5%. Soil moisture content was measured in-situ using a portable time-domain reflectometry (TDR). Each treatment was replicated three times, with a plot area of ​​30 m². 2 , randomized block arrangement. Example 1

[0020] (1) Weeding before sowing: 15 days before sowing, on a sunny and windless day, mix 200 mL / mu of 20% glufosinate with 45 kg of water (the soil moisture content measured by TDR is 12% (<15%)) and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle (working pressure 0.2 MPa, droplet size 200 μm).

[0021] (2) Pre-emergence herbicide application: Before emergence after sowing, the soil was artificially irrigated to bring the moisture content of the 0-5 cm soil layer to 60% of the field capacity. The soil was then allowed to dry naturally for 12 hours until the surface soil was slightly dry and not compacted. The surface moisture content measured by TDR was 14% (<15%).

[0022] Mix 100 g / mu of 60% butachlor and 60 g / mu of bensulfuron-methyl with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle (droplet diameter 300 μm) to form a film layer.

[0023] (3) Weeding during the seedling stage: Twenty days after emergence, the soil moisture content measured by TDR was 13% (<15%). 40 g / mu of a 1:1 mixture of dichloroquinoline and pyrimisulfuron + 60 mL / mu of a 1:1 mixture of 2,4-D and clopyralid were diluted with 45 kg of water and sprayed directionally with a sprayer height of 30 cm and a walking speed of 0.8 m / s, avoiding the central leaves of the upland rice to ensure precise coverage of the weed stems and leaves.

[0024] (4) Weed control in the early tillering stage: a) 35 days after emergence, mix 35 mL / mu of cyhalofop-butyl with 22 g / mu of chlorpyrifos, add 45 kg of water, and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. b) Ten days later, mix the compound preparation (containing 2.5% pentafluoride + 10% cyanoflus) 80 mL / mu + 2.5% pentafluoride single agent 40 mL / mu with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. c) Three days later, mix 3 mL / mu of 0.01% brassinolide and 20 g / mu of potassium dihydrogen phosphate with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. (5) Mid-to-late stage of tillering prevention: 55 days after emergence, if there is a small amount of goosegrass residue, mix 60 g / mu of a 1:1 compound preparation of dichloroquinoline acid and pyrimisulfuron + 80 mL / mu of a 1:1 compound preparation of 2,4-D and clopyralid, dilute with 45 kg of water, and spray with a backpack electric sprayer with a fan-shaped atomizing nozzle; 3 days later, mix 20 mL / mu of 0.2% naphthaleneacetic acid + 600 g / mu of urea + 25 g / mu of potassium dihydrogen phosphate, dilute with 45 kg of water, and spray with a backpack electric sprayer with a fan-shaped atomizing nozzle. Example 2

[0025] (1) Weeding before sowing: 12 days before sowing, on a sunny and windless day, mix 225 mL / mu of 20% glufosinate with 40 kg of water (the soil moisture content measured by TDR is 18%) and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle (working pressure 0.25 MPa, droplet size 250 μm).

[0026] (2) Pre-emergence herbicide application: Before emergence after sowing, the soil was artificially irrigated to bring the moisture content of the 0-5 cm soil layer to 65% of the field capacity. The soil was then allowed to dry naturally for 18 hours until the surface soil was slightly dry and not compacted. The surface moisture content measured by TDR was 19%.

[0027] Mix 110 g / mu of 60% butachlor and 65 g / mu of bensulfuron-methyl with 40 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle (droplet diameter 350 μm) to form a film layer.

[0028] (3) Weeding during the seedling stage: Seventeen days after emergence, TDR measured the soil moisture content at 22%. 45g / mu of a 1:1 mixture of quinclorac and pyrimisulfuron-methyl + 70 mL / mu of a 1:1 mixture of 2,4-D and clopyralid, diluted with 40 kg of water, was used for directional spraying. The sprayer was 35 cm high, and the walking speed was 1.0 m / s, avoiding the central leaves of the upland rice to ensure precise coverage of the weed stems and leaves.

[0029] (4) Weed control in the early tillering stage: a) 33 days after emergence, mix 37.5 mL / mu of cyhalofop-butyl and 23.5 g / mu of chlorpyrifos with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. b) Ten days later, mix the compound preparation (containing 3.5% pentafluoride + 13% cyanoflus) at 85 mL / mu and 2.5% pentafluoride single agent at 45 mL / mu with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. c) Three days later, mix 4 mL / mu of 0.01% brassinolide and 22.5 g / mu of potassium dihydrogen phosphate with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. (5) Mid-to-late stage of tillering prevention: 50 days after emergence, if there is a small amount of goosegrass residue, mix 70 g / mu of a 1:1 compound preparation of dichloroquinoline acid and pyrimisulfuron + 90 mL / mu of a 1:1 compound preparation of 2,4-D and clopyralid, dilute with 45 kg of water, and spray with a backpack electric sprayer with a fan-shaped atomizing nozzle; 3 days later, mix 22.5 mL / mu of 0.2% naphthaleneacetic acid + 700 g / mu of urea + 27.5 g / mu of potassium dihydrogen phosphate, dilute with 45 kg of water, and spray with a backpack electric sprayer with a fan-shaped atomizing nozzle. Example 3

[0030] (1) Weeding before sowing: 10 days before sowing, on a sunny and windless day, mix 250 mL / mu of 20% glufosinate with 30 kg of water (the soil moisture content measured by TDR is 28%) and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle (working pressure 0.3 MPa, droplet size 300 μm).

[0031] (2) Pre-emergence herbicide application: Before emergence after sowing, the soil was artificially irrigated to bring the moisture content of the 0-5 cm soil layer to 70% of the field capacity. The soil was then allowed to dry naturally for 24 hours until the surface soil was slightly dry and not compacted. The surface moisture content measured by TDR was 26%.

[0032] Mix 120 g / mu of 60% butachlor and 70 g / mu of bensulfuron-methyl with 30 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle (droplet diameter 400 μm) to form a film layer.

[0033] (3) Weeding during the seedling stage: 25 days after emergence, TDR measured the soil moisture content at 27%. 50 g / mu of a 1:1 mixture of dichloroquinoline and pyrimisulfuron + 75 mL / mu of a 1:1 mixture of 2,4-D and clopyralid, diluted with 30 kg of water, was used for directional spraying. The sprayer was 40 cm high, and the walking speed was 1.2 m / s, avoiding the central leaves of the upland rice to ensure precise coverage of the weed stems and leaves.

[0034] (4) Weed control in the early tillering stage: a) 30 days after emergence, mix 40 mL / mu of cyhalofop-butyl with 25 g / mu of chlorpyrifos and 45 kg of water, and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. b) Ten days later, mix the compound preparation (containing 5% pentafluoride + 15% cyanoflus) 90 mL / mu + 2.5% pentafluoride single agent 50 mL / mu with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. c) Three days later, mix 5 mL / mu of 0.01% brassinolide and 25 g / mu of potassium dihydrogen phosphate with 45 kg of water and spray using a backpack electric sprayer with a fan-shaped atomizing nozzle. (5) Mid-to-late stage of tillering prevention: 45 days after emergence, if there is a small amount of goosegrass residue, mix 80 g / mu of a 1:1 compound preparation of dichloroquinoline acid and pyrimisulfuron + 100 mL / mu of a 1:1 compound preparation of 2,4-D and clopyralid, dilute with 45 kg of water, and spray with a backpack electric sprayer with a fan-shaped atomizing nozzle; 3 days later, mix 25 mL / mu of 0.2% naphthaleneacetic acid + 800 g / mu of urea + 30 g / mu of potassium dihydrogen phosphate, dilute with 45 kg of water, and spray with a backpack electric sprayer with a fan-shaped atomizing nozzle.

[0035] Comparative Example 1 This comparative example follows the same procedure as Example 2, except that brassinolide, naphthaleneacetic acid, and foliar fertilizer are omitted in steps (4)c) and (5)b).

[0036] Comparative Example 2 This comparative example follows the same procedure as Example 2, but the brassinolide in step (4) is applied simultaneously with weeding before sowing.

[0037] Comparative Example 3 Before sowing, apply 200 mL / mu of glufosinate; 15 days after emergence, spray once with 50 g of a 1:1 mixture of quinclorac and pyrimisulfuron + 75 mL of a 1:1 mixture of 2,4-D and clopyralid + 100 g of butachlor, diluted in 30 kg of water. No pre-emergence, no relay, and no regulators are required.

[0038] Data Analysis and Comparison To objectively evaluate the technical effects of this invention, the total weed control efficacy (%), phytotoxicity level, effective tiller number (plants / hole), and yield (kg / acre) were tested on the plots treated in Examples 1-3 and Comparative Examples 1-3. All tests employed standardized methods, as detailed below: (1) Overall weed control efficacy (%) Five 1 m × 1 m quadrats were randomly selected from each treatment plot. The number of surviving weeds was investigated 30 days after the application of the herbicide. The total weed control efficacy (%) was calculated using the formula: (1 - number of weeds in the treatment area / number of weeds in the control area) 100%, with the control area being a blank plot without any herbicide application. Crataegus pinnatifida, Eleusine indica, Echinochloa crus-galli, and Eclipta prostrata were counted separately and then weighted averaged according to their community proportions (40%:25%:20%:15%).

[0039] (2) Grade of phytotoxicity The field efficacy of pesticides is classified into levels 0-5, as follows: Level 0: No visible symptoms of pesticide damage; Level 1: Mild pesticide damage, such as slight yellowing, spots, or slight softening of leaves, which does not affect normal crop growth and final yield; Level 2: Moderate pesticide damage, such as obvious yellowing, curling, or local necrosis of leaves, with slightly inhibited plant growth but recoverable, and minimal impact on yield (<10%); Level 3: Severe pesticide damage, such as twisted central leaves, inhibited tillering nodes, and partial leaf death, with significantly stunted plants, a 10-25% reduction in effective tillers, and a 10-20% yield loss; Level 4: Severe pesticide damage, such as stunted main stem growth, death of most tillers, and hindered root development, with severely stunted or deformed plants, a 25-50% reduction in effective tillers, and a 20-40% yield loss; Level 5: Extremely severe pesticide damage, such as large-scale plant death, inability to head normally, or total crop failure, with a yield loss >40% or no harvest at all.

[0040] Three agronomists with intermediate or higher professional titles independently observed and recorded the pesticide application 7, 15, and 30 days after application. They scored the pesticides according to the above standards, took the arithmetic mean (retaining one decimal place), and finally determined the pesticide damage level by rounding to the nearest whole number.

[0041] (3) Number of effective tillers (plants / hole) At the early heading stage (about 75 days after sowing), 20 holes were randomly marked in each treatment plot, and the number of main stems and effective tillers (ear length ≥10 cm) in each hole were counted and the average value was taken.

[0042] (4) Yield (kg / mu) The harvested grains from the processing plots were threshed, dried to a moisture content of 13%, and weighed before being converted to yield per mu (1 mu = 667 m³). 2 The harvested area is 20 m in the center of the plot. 2 Remove marginal effects.

[0043] The test results are summarized in Table 1.

[0044] Table 1

[0045] Table 1 shows that the total weed control efficacy of Examples 1-3 was 95.2%, 96.5%, and 96.1%, respectively, all significantly higher than that of Comparative Example 3 (76.4%) and Comparative Example 2 (82.6%). Among them, Example 2 achieved a control efficacy as high as 96.5%. Comparative Example 3, using traditional paddy field weeding methods, failed to effectively control the secondary germination of highly resistant weeds such as *Eleusine indica*, *Echinochloa crus-galli*, and *Eclipta prostrata* in tropical regions. Comparative Example 2, due to incorrect timing of herbicide application, interfered with the absorption and translocation of the herbicide within the weeds, resulting in a significant decrease in control efficacy. These results indicate that the present invention, through five-stage sequential synergistic application and herbicide rotation, can effectively address the rapid germination and herbicide resistance problems of noxious weeds in tropical upland paddy fields.

[0046] The herbicide damage levels in Examples 1-3 were all grade 0, indicating that no visible herbicide damage symptoms appeared in the upland rice plants throughout their growth period. In contrast, Comparative Example 1 (lacking the regulator) had a herbicide damage level of grade 2, manifested as moderate yellowing of leaves and inhibited tillering; Comparative Example 3 had a herbicide damage level of grade 3, showing severe stunting of plants and inhibited tillering node development. This difference demonstrates that relying solely on herbicides is insufficient to balance efficacy and safety. The present invention, by introducing brassinolide and foliar fertilizer within a specific time window (3 days after herbicide application), can effectively alleviate herbicide stress and ensure normal growth of upland rice.

[0047] The effective tiller number in Examples 1-3 was 8.7-9.1 plants / hole, significantly higher than that in Comparative Example 1 (6.8 plants / hole), Comparative Example 2 (7.5 plants / hole), and Comparative Example 3 (5.1 plants / hole). Correspondingly, the yield of Examples 1-3 was 385-402 kg / mu, an increase of 30.5%-36.3% compared to Comparative Example 3 (295 kg / mu). These results indicate that the present invention not only did not negatively impact the growth of upland rice, but also promoted tillering and robust plant growth through the synergistic effect of regulators and nutrients, ultimately achieving stable and increased yield.

[0048] Examples 1 (soil moisture content 12%-14%), 2 (18%-22%), and 3 (26%-28%) simulated three typical tropical soil moisture conditions: drought, adequate moisture, and wet conditions, respectively, and all achieved stable high efficacy and zero phytotoxicity. This demonstrates that the present invention, by dynamically adjusting the water dosage based on soil moisture content and combining it with appropriate droplet size and application parameters, can maintain consistent technical effects under different moisture conditions and possesses good field applicability.

[0049] In summary, the present invention provides a highly efficient and safe weed control method for tropical upland rice fields. Compared with existing technologies, it has significant beneficial effects such as high weed control efficacy, good crop safety, stable yield, and strong adaptability. It solves the technical problems of "insufficient control efficacy," "frequent herbicide damage," and "ignoring the dynamics of soil moisture in dryland crops" in existing technologies, and provides a highly efficient, safe, stable-yielding, and scalable integrated weed control method.

Claims

1. A method for efficient and safe weed control in tropical upland rice fields, characterized in that, The method comprises the following five stages, performed sequentially: (1) Weed control before sowing: 10 to 15 days before sowing, spray 200-250 ml / mu of 20% glufosinate-ammonium aqueous solution, diluted with 30-45 kg of water, to kill the weeds that have already sprouted. (2) Pre-emergence herbicide application: After sowing and before the emergence of upland rice seedlings, spray 100-120 g / mu of 60% butachlor and 60-70 g / mu of bensulfuron-methyl after the soil surface is moistened and naturally dried, and dilute with 30-45 kg of water to form a pre-emergence herbicide film. (3) Seedling stage weeding: 15 to 20 days after the emergence of upland rice, spray 40-50 g / mu of 1:1 compound preparation of dichloroquinoline acid and pyrimisulfuron and 60-75 ml / mu of 1:1 compound preparation of 2,4-D and clopyralid, diluted with 30-45 kg of water for targeted weeding during the seedling stage. (4) Weeding in the early tillering stage: 30 to 35 days after the emergence of upland rice seedlings, weeding should be carried out in sequence as follows: a) Spray 35-40 ml / mu of cyhalofop-butyl and 22-25 g / mu of chlorpyrifos, diluted with 45 kg of water; b) Ten days after application in a), spray 80-90 ml / mu of a compound formulation containing 2.5%-5% penoxsulam and 10%-15% cyhalofop-butyl, along with 40-50 ml / mu of 2.5% penoxsulam single agent, diluted with 45 kg of water. c) Three days after b), spray with 3-5 ml / mu of 0.01% brassinolide and 20-25 g / mu of potassium dihydrogen phosphate, diluted in 45 kg of water. (5) Mid-to-late tillering control: If noxious weeds still exist in the field 40 to 55 days after the emergence of upland rice seedlings, then: a) Spray 60-80 g / mu of a 1:1 mixture of dichloroquinoline acid and pyrimisulfuron, and 80-100 ml / mu of a 1:1 mixture of 2,4-D and clopyralid, diluted with 45 kg of water. b) Three days after the application of the pesticide in a), spray with 20-25 ml / mu of 0.2% naphthaleneacetic acid, 25-30 g / mu of potassium dihydrogen phosphate and 600-800 g / mu of urea, diluted with 45 kg of water. The amount of water added in steps (1), (2), and (3) is dynamically adjusted according to the soil moisture content: 45 kg / mu when the soil moisture content is below 15%, 30 kg / mu when it is above 25%, and 35-45 kg / mu when the soil moisture content is between 15% and 25%. The method is applicable to tropical upland rice planting areas with an average annual temperature of 25-30℃, an annual rainfall of 1500-2000 mm, and an air humidity of 80%-90%.

2. The method for efficient and safe weed control in tropical upland rice fields according to claim 1, characterized in that, In step (1), the field is kept free of standing water from the time of application until sowing, and the application is carried out in a clear and windless weather. A fan-shaped atomizing nozzle is used, with a working pressure of 0.2-0.3 MPa and a droplet size of 200-300 micrometers.

3. The method for efficient and safe weed control in tropical upland rice fields according to claim 1, characterized in that, In step (2), the surface soil is moistened to bring the water content of the 0-5 cm soil layer to 60%-70% of the field capacity, and then allowed to dry naturally for 12-24 hours to make the surface soil slightly dry and not compacted. The spray droplets have a particle size of 300-400 micrometers to form a stable film layer on the soil surface.

4. The method for efficient and safe weed control in tropical upland rice fields according to claim 1, characterized in that, In step (3), directional spraying technology is used, with the spray bar 30-40 cm above the ground and a walking speed of 0.8-1.2 m / s, avoiding the heart leaves of upland rice to ensure that the liquid accurately covers the stems and leaves of weeds.

5. The method for efficient and safe weed control in tropical upland rice fields according to claim 1, characterized in that, The soil moisture content was measured on-site using a portable time domain reflectometer (TDR) to guide the dynamic adjustment of the water dilution amount.

6. The method for efficient and safe weed control in tropical upland rice fields according to claim 1, characterized in that, The method has a comprehensive control effect of no less than 95% on crabgrass, goosegrass, sedge and wormwood, and the herbicide damage level of upland rice is 0.

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