Method for preventing and controlling weeds in alfalfa field and application

Abstract

The invention discloses a method for preventing and controlling weeds in an alfalfa field and application, and belongs to the technical field of weed prevention and control. 5% imazethapyr and 10.8% haloxyfop-R-methyl are applied in a combined mode, or 30% 2, 4-sodium butyrate and 10.8% haloxyfop-R-methyl are applied in a combined mode, spraying is carried out in the 2-5 leaf period of weeds, synergistic interaction is achieved by adjusting the application amount, the obvious control effect on chenopodium weeds and grassy weeds can be achieved at the same time, the safety to alfalfa is improved, and the weeding composition has a good application prospect. The yield and the nutritional quality of the alfalfa are improved, reduction and efficiency increase are realized, and the method has important significance for improving the yield of the alfalfa and guaranteeing the quality of the alfalfa.

Description

Technical Field

[0001] The invention belongs to the technical field of weed control, and in particular relates to a method for controlling weeds in an alfalfa field and application thereof. Background Art

[0002] Alfalfa Medicago sativa ) is an ancient cultivated forage grass, a cross-pollinated homologous tetraploid legume, and one of the largest forage grasses in the world. Alfalfa has a strong regeneration ability and can quickly resume growth after mowing. It is known as the "king of forage grasses" because of its high nutritional value, good palatability, strong adaptability to the environment, good regeneration, and high and stable yield. Adding alfalfa to livestock and poultry feed can significantly improve the digestion efficiency of herbivorous animals and improve the production performance of livestock and poultry, especially playing a key role in the safe production of milk. Alfalfa cultivation is of great significance to ensuring the safe production of the dairy industry.

[0003] Weeds in alfalfa fields are a biological disaster that seriously threatens alfalfa production. In the early stages of alfalfa field establishment, weeds compete with alfalfa for water, fertilizer, and light, occupying plant growth space. At the same time, as hosts of alfalfa field pests and diseases, they facilitate the spread and transmission of pests and diseases, seriously affecting the growth and development of alfalfa. The growth patterns of weeds in alfalfa fields vary at different sowing times, and weed control is complex at different growth and development stages. Failure to pay attention to weed control can reduce hay yield and quality at best, or even lead to planting failure and seed destruction at worst. Therefore, improving weed control effectiveness is of great significance to increasing alfalfa yield and ensuring alfalfa quality.

[0004] Alfalfa field weeds are mainly divided into two categories: grass weeds and broadleaf weeds. Among them, annual broadleaf weeds such as Chenopodium album, Chenopodium album, and Amaranthus retroflexus are the most harmful to alfalfa in the year of sowing. In production, the commonly used stem and leaf treatment herbicide for alfalfa fields is imidacloprid, but imidacloprid has the following problems in production and application: 1. The residual period is long and not easy to degrade; 2. Long-term repeated use causes phytotoxicity to crops, resulting in reduced yield or death; 3. Repeated excessive application causes weed resistance; 4. It causes serious phytotoxicity to subsequent crops, making the crops short and yellow, with low seed yield, forming a "cancer field"; 5. The weed control spectrum of stem and leaf treatment herbicides is narrow, and the comprehensive analysis of weeds is low; therefore, it is urgent to find a safe and efficient control method that can replace imidacloprid, reduce the amount and increase the efficiency. Summary of the invention

[0005] In view of this, the object of the present invention is to provide a method for controlling weeds in alfalfa fields, which has good control effects on both Chenopodiaceae and Poaceae weeds, reduces the amount of herbicide used, and can also improve the yield and quality of alfalfa.

[0006] Another object of the present invention is to provide an application of the method in increasing alfalfa yield and improving alfalfa quality.

[0007] To achieve the above-mentioned invention object, the present invention provides the following technical solutions: The present invention provides a method for controlling weeds in alfalfa fields, and the weeds include one or several of Chenopodium serotinum, Setaria viridis and Panicum miliaceum; The method comprises the following steps: spraying a herbicide composition at the 2-5 leaf stage of the weeds; The herbicide composition comprises component A and component B, component A is 5% imazethapyr or 30% sodium 2,4-dichlorophenoxyacetate, and component B is 10.8% haloxyfop-P-methyl; When component A is 5% imazethapyr, the volume ratio of component A to component B is 3-4:1; the application amount of the herbicide composition is 975-1462.5 mL / hm 2 ; When component A is 30% sodium 2,4-dichlorophenoxyacetate, the volume ratio of component A to component B is 4-6:1; the application amount of the herbicide composition is 1350-2025 mL / hm 2 。

[0008] Preferably, when component A is 5% imazethapyr, the volume ratio of component A to component B is 10:3, and the application amount of the herbicide composition is 975 mL / hm 2 ; when component A is 30% sodium 2,4-dichlorophenoxyacetate, the volume ratio of component A to component B is 5:1, and the application amount of the herbicide composition is 2025 mL / hm 2 。

[0009] Preferably, the application frequency of the herbicide composition is 1 time.

[0010] Preferably, the preparation method of the herbicide composition comprises: mixing component A and component B to obtain the herbicide composition.

[0011] The present invention also provides an application of the method in increasing the yield and improving the quality of alfalfa.

[0012] Preferably, the variety of the alfalfa includes Zhongcao No. 3.

[0013] Preferably, the increase in alfalfa yield includes increasing one or several of alfalfa plant height, fresh weight, dry weight and leaf area.

[0014] Preferably, the improvement of alfalfa quality includes increasing one or several of alfalfa crude protein content, reducing acid detergent fiber content, reducing neutral detergent fiber content and increasing relative feeding value.

[0015] The beneficial effects of the present invention: The present invention applies a combination of 5% imazethapyr and 10.8% haloxyfop-P-methyl, or a combination of 30% sodium 2,4-D butyrate and 10.8% haloxyfop-P-methyl, spraying at the 2-5 leaf stage of weeds. By adjusting the application rate, synergistic effects are achieved, which can simultaneously show significant control effects on Chenopodiaceae weeds and Gramineae weeds, improve the safety for alfalfa, increase alfalfa yield and nutritional quality, achieve reduction in dosage and increase in efficiency, and are of great significance for increasing alfalfa yield and ensuring alfalfa quality. Description of the Drawings

[0016] Figure 1 For the effect of the mixture of herbicides at different concentrations on the leaf area of alfalfa in Example 3, where MZ+GX is 5% imazethapyr + 10.8% haloxyfop-P-methyl, JM+GX is 24% imazapic + 10.8% haloxyfop-P-methyl, PC+GX is 50% prometryn + 10.8% haloxyfop-P-methyl, and DB+GX is 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl. Detailed Embodiments

[0017] The present invention provides a method for controlling weeds in alfalfa fields, and the weeds include one or more of Chenopodium serotinum, Setaria viridis, and Panicum miliaceum; The method includes the following steps: spraying a herbicide composition at the 2-5 leaf stage of weeds; The herbicide composition includes component A and component B. Component A is 5% imazethapyr or 30% sodium 2,4-D butyrate, and component B is 10.8% haloxyfop-P-methyl; When component A is 5% imazethapyr, the volume ratio of component A to component B is 3-4:1; the application rate of the herbicide composition is 975-1462.5 mL / hm 2 ; When component A is 30% sodium 2,4-D butyrate, the volume ratio of component A to component B is 4-6:1; the application rate of the herbicide composition is 1350-2025 mL / hm 2 。

[0018] In the present invention, the sources of 5% imazethapyr, 30% sodium 2,4-D butyrate, and 10.8% haloxyfop-P-methyl are not particularly limited and can be obtained by purchasing through conventional channels.

[0019] In the present invention, when component A is 5% imazethapyr, the volume ratio of component A to component B is preferably 3.2-3.5:1 or 10:3; the application rate of the herbicide composition is preferably 975-1462.5 mL / hm 2 , such as 975 mL / hm 2 , 1000 mL / hm 2, 1200 mL / hm 2 , 1200 mL / hm 2 or 1300 mL / hm 2 .

[0020] In the present invention, when the component A is 30% sodium 2,4-dichlorophenoxyacetate, the volume ratio of component A to component B is preferably 4.5 - 5.5:1 or 5:1; the application rate of the herbicide composition is preferably 1350 - 2025 mL / hm 2 , for example 1500 mL / hm 2 , 1800 mL / hm 2 , 1900 mL / hm 2 , 2000 mL / hm 2 , 2025 mL / hm 2 .

[0021] In the present invention, the application frequency of the herbicide composition is preferably 1 time.

[0022] In the present invention, the preparation method of the herbicide composition preferably includes: mixing component A and component B to obtain the herbicide composition. The mixing method can be conventionally selected according to actual needs.

[0023] In the present invention, the herbicide composition is diluted with water and then sprayed, and the dilution ratio is preferably 1:100 - 1:450, more preferably 1:110 - 150 or 1:147 - 225 or 1:153 - 210 or 1:205 - 310.

[0024] The present invention also provides an application of the method in increasing the yield and improving the quality of alfalfa.

[0025] In the present invention, there is no special limitation on the alfalfa variety, and it preferably includes Zhongcao No. 3. In the present invention, the increase in alfalfa yield includes increasing one or more of the plant height, fresh weight, dry weight, and leaf area of alfalfa. The improvement in alfalfa quality includes increasing one or more of the crude protein content, reducing the acid detergent fiber content, reducing the neutral detergent fiber content, and increasing the relative feeding value of alfalfa.

[0026] The control method of the present invention can effectively control Chenopodiaceae weeds and Gramineae weeds, and at the same time can also increase the plant height, fresh weight, dry weight, and leaf area of alfalfa. Compared with the water treatment group, the control method of the present invention increases the plant height by 8.52% - 31.92%, the fresh weight by 130.07% - 155.62%, the dry weight by 117.09% - 144.85%, and the leaf area by 12.06% - 52.58%; compared with the manual weeding treatment group, the leaf area is increased by up to 18.71% - 21.60%.

[0027] In addition, the prevention and control method of the present invention can also improve the quality of alfalfa. The crude protein content of alfalfa is higher than 22%, the acid detergent fiber content is lower than 17%, the neutral detergent fiber content is lower than 33%, and the relative feeding value is higher than 210. Compared with the water treatment group, the prevention and control method of the present invention increases the crude protein content by 3.03% - 4.13%, reduces the acid detergent fiber content by 4.44 - 16.11%, reduces the neutral detergent fiber content by 2.22% - 5.74%, and increases the relative feeding value by 3.02% - 8.88%.

[0028] The present invention applies a mixture of 5% imazethapyr and 10.8% haloxyfop - R - methyl, or a mixture of 30% sodium 2,4 - D butyrate and 10.8% haloxyfop - R - methyl. By adjusting the application rate, synergistic effects are achieved, which can simultaneously show significant control effects on Chenopodiaceae weeds and Gramineae weeds, improve the safety for alfalfa, increase the alfalfa yield and nutritional quality, and achieve reduction in chemical usage and increase in efficiency.

[0029] The following examples are used to illustrate in detail the technical solutions provided by the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0030] In the following examples, unless otherwise specified, all are conventional methods.

[0031] In the following examples, the materials, reagents, etc. used, unless otherwise specified, can all be obtained from commercial channels.

[0032] Example 1 Effects of Different Kinds of Stem - Leaf - Treated Herbicides on the Safety of Alfalfa and Field Weeds 1. The tested herbicides and application doses are shown in Table 1. The tested alfalfa variety is Zhongcao No. 3 (from the College of Life Sciences, Inner Mongolia University), with a germination rate of 85%. The Chenopodiaceae weed seeds are Chenopodium serotinum (collected from the experimental field in Hohhot in October 2021), with a germination rate of 25%. The Gramineae weed seeds are Setaria viridis and Panicum dichotomiflorum (collected from the experimental field in Hohhot in October 2021), with a germination rate of 30%.

[0033] Table 1 Test Materials and Treatments

[0034] 2. Field Test Method The test was carried out in the experimental field in Hohhot, Inner Mongolia Autonomous Region. Before the test, large weeds in the test plot were removed to ensure that the weed levels were the same before the test implementation and there were no significant differences between plots. Water was applied before sowing, and the alfalfa, Chenopodium serotinum, and Gramineae weed seeds were mixed evenly. The seeding rate of alfalfa was 300 seeds / m 2 , the seeding rate of Chenopodium serotinum was 400 seeds / m 2 , and the seeding rate of the mixed Gramineae weed seeds was 200 seeds / m 2, row spacing of 30 cm, row sowing, and field management followed the conventional field management standards. A total of 17 treatments were set up in the experiment, including 15 test agents, spraying water and manual weeding treatment (Table 1). Each agent was diluted with water and sprayed. The spraying rate of each agent after dilution with water was 300L / hm 2 , the clean water spraying volume for clean water treatment is 300L / hm 2 , manual weeding treatment only carried out manual weeding. The alfalfa plot area was 5m×2m, and a randomized complete block design was used with 3 replicates. Each agent was sprayed once on July 26, 2022 (3-leaf stage of weeds) using the recommended concentration in the product instructions. On the same day, the manual weeding group was treated with manual weeding, and the clean water group was sprayed with clean water.

[0035] 3. Measurement indicators and methods (1) Safety observation: Observe the growth of alfalfa 30 days after application, and record the plant height, fresh weight and dry weight of alfalfa.

[0036] (2) Observation of weed control effect: 30 days after application, randomly select 1m2 2 Three sampling points were set up to record the types and numbers of Gramineae weeds and Chenopodiaceae weeds, and calculate the control effect. 2 There are 3 sampling points, where weeds from the Gramineae family and weeds from the Chenopodiaceae family are collected respectively, their fresh weed masses are weighed, and the fresh control efficacy is calculated (gramineae and Chenopodiaceae weeds are weighed separately).

[0037]

[0038]

[0039] 4. Test results (1) Safety analysis of alfalfa The effects of 15 stem-leaf herbicides on alfalfa plant height, fresh weight and dry weight were evaluated, and the results are shown in Table 2. The results showed that 10 stem-leaf herbicides, such as 48% metribuzin, caused different degrees of phytotoxicity to alfalfa seedlings; 5 stem-leaf herbicides, including 5% imazamethoate, 24% imipenem, 50% promethazine, 10.8% high-efficiency halpyrazole, and 30% 2,4-D sodium salt, were safe for alfalfa, among which 30% 2,4-D sodium salt could significantly promote alfalfa plant height and increase alfalfa fresh weight and dry weight.

[0040] Table 2 Effects of different herbicides on plant height, fresh weight and dry weight of alfalfa

[0041] (2) Analysis of weed control effects By evaluating the effects of 15 post - emergence herbicides on the control efficacy of weeds in terms of plant population, the results are shown in Table 3. The results indicate that for Chenopodiaceae weeds, after applying 48% metamitron or 25% fomesafen, the control efficacy of weed plant population is significantly different from that of other treatments, and the control efficacy of weed plant population can reach 100%; for Gramineae weeds, after applying 10.8% haloxyfop - R - methyl, 5% imazethapyr, 24% oxyfluorfen, 48% metamitron or 25% fomesafen, the control efficacy of weed plant population is significantly different from that of other treatments, and the control efficacy of weed plant population can reach 100.00%.

[0042] Table 3 Control efficacy of weed plant population by different herbicides

[0043] Note: The statistical data results are shown as mean ± standard deviation, and the significance analysis P < 0.05.

[0044] By evaluating the effects of 15 post - emergence herbicides on the control efficacy of weeds in terms of fresh weight, the results are shown in Table 4. The results indicate that for Chenopodiaceae weeds, after applying 48% metamitron or 25% fomesafen, the control efficacy of weed fresh weight is significantly different from that of other treatments, and the control efficacy of weed fresh weight can reach 100.00%; for Gramineae weeds, after applying 10.8% haloxyfop - R - methyl, 5% imazethapyr, 24% oxyfluorfen, 48% metamitron or 25% fomesafen, the control efficacy of weed fresh weight is significantly different from that of other treatments, and it can reach 100.00%.

[0045] Table 4 Control efficacy of weed fresh weight by different herbicides

[0046] Note: The statistical data results are shown as mean ± standard deviation, and the significance analysis P < 0.05.

[0047] Combined with the safety and efficacy analysis of 15 post - emergence herbicides, a total of 5 safe and highly effective post - emergence herbicides were screened out, namely: 5% imazethapyr, 24% imazapic, 50% prometryn, 10.8% haloxyfop - R - methyl, 30% 2,4 - D sodium butyrate.

[0048] Example 2 Effects of post - emergence herbicides at different concentrations on the safety of alfalfa and field weeds 1. Test materials: The tested herbicides and their concentration settings are shown in Table 5; the tested alfalfa variety is Zhongcao No. 3 (from the College of Life Sciences, Inner Mongolia University), with a germination rate of 85%; the seeds of Chenopodiaceae weeds are Chenopodium serotinum (harvested from the experimental field in Hohhot in October 2021), with a germination rate of 25%; the seeds of Gramineae weeds are Setaria viridis and Panicum miliaceum (harvested from the experimental field in Hohhot in October 2021), with a germination rate of 30%.

[0049] Table 5 Tested herbicides and their concentrations

[0050] 2. Field test method The test was carried out in the experimental field in Hohhot, Inner Mongolia Autonomous Region. Before the test, large weeds in the test plot were removed to ensure that the weed levels were the same before the test implementation and there were no significant differences between plots. Water was applied before sowing. Seeds of alfalfa, Chenopodium serotinum, and Gramineae weeds were mixed evenly. The seeding rate of alfalfa was 300 seeds / m 2 , the seeding rate of Chenopodium serotinum was 400 seeds / m 2 , and after the seeds of Gramineae weeds were mixed evenly, the seeding rate was 200 seeds / m 2 . The row spacing was 30 cm, and sowing was in drills. Field management adopted the conventional management standards for large fields. A total of 22 treatments were set in the test, including 20 different concentrations of the tested pesticides, spraying clear water, and manual weeding (Table 4). After the different concentrations of pesticides were diluted with water, they were sprayed. The spraying amount of each diluted pesticide with different concentrations was 300 L / hm 2 , the spraying amount of clear water in the clear water treatment was 300 L / hm 2 , and only manual weeding was carried out in the manual weeding treatment. The area of the alfalfa plot was 5 m × 4 m, and a randomized complete block experimental design was adopted. 4 sampling points of 1 m 2 were selected in each plot. According to the "Pesticide Field Efficacy Test Guidelines Part 23: Herbicides for Controlling Weeds in Alfalfa Fields" (NY / T 1464.23 - 2007), 4 concentration gradients of low, medium, high, and double the medium amount were set for each pesticide. On June 25, 2023 (when the weeds were at the 3 - leaf stage), they were sprayed once. On the same day, the manual weeding group carried out manual weeding treatment, and the clear water group sprayed clear water.

[0051] 3. Safety analysis of alfalfa: The same method as in Example 1 was used for safety observation.

[0052] By evaluating the effects of different concentrations of 5 foliar - applied herbicides obtained through primary screening on the plant height, fresh weight, and dry weight of alfalfa, the results are shown in Table 6. The results show that different concentrations of foliar - applied herbicides have different effects on the growth indicators of alfalfa; 5% imazethapyr, 24% imazapic, 30% sodium 2,4 - D butyrate, and 50% prometryn show a trend of inhibition at high concentrations on the plant height, fresh weight, and dry weight of alfalfa.

[0053] Table 6 Effects of different concentrations of herbicides on the plant height, fresh weight, and dry weight of alfalfa

[0054] 4. Weed control effect analysis: The same method as in Example 1 was used for observing the weed control effect.

[0055] (1) Effects of different concentrations of foliar - applied herbicides on the plant control efficacy of weeds By evaluating the effects of different concentrations of 5 post-emergence herbicides obtained through primary screening on the control efficacy of Chenopodiaceae weeds and Gramineae weeds, the results are shown in Table 7. The results indicate that as the concentration of the applied herbicide increases, the control efficacy of Chenopodiaceae weeds and Gramineae weeds gradually increases; the control efficacy of 5% imazethapyr, 24% imazapic, 30% sodium 2,4-D butyrate, and 50% prometryn against various weeds can all reach over 60.00%; 10.8% haloxyfop-R-methyl alone in controlling Gramineae weeds can achieve a relatively high control efficacy even at the lowest concentration..

[0056] Table 7 Control efficacy of weeds by herbicides at different concentrations

[0057] Note: The statistical data results are shown as mean ± standard deviation, and the significance analysis P < 0.05.

[0058] (2)Effect of post-emergence herbicides at different concentrations on the fresh weight control efficacy of weeds By evaluating the effects of different concentrations of 5 post-emergence herbicides obtained through primary screening on the fresh weight control efficacy of Chenopodiaceae weeds and Gramineae weeds, the results are shown in Table 8. The results indicate that as the concentration of the applied herbicide increases, the fresh weight control efficacy of Chenopodiaceae weeds gradually increases, while the change in the fresh weight control of Gramineae weeds is relatively small; the fresh weight control efficacy of 5% imazethapyr, 24% imazapic, 30% sodium 2,4-D butyrate, and 50% prometryn against various weeds can all reach over 65.00%; 10.8% haloxyfop-R-methyl alone in controlling Gramineae weeds can achieve a relatively high control efficacy even at the lowest concentration.

[0059] Table 8 Fresh weight control efficacy of weeds by herbicides at different concentrations

[0060] Note: The statistical data results are shown as mean ± standard deviation, and the significance analysis P < 0.05.

[0061] By combining the safety and efficacy analysis of different concentrations of 5 post-emergence herbicides, the optimal concentrations are respectively: 1500 mL / hm 2 (5% imazethapyr), 300 mL / hm 2 (24% imazapic), 1875 mL / hm 2 (50% prometryn); 450 mL / hm 2 (10.8% haloxyfop-R-methyl), 2250 mL / hm 2 (30% sodium 2,4-D butyrate).

[0062] Example 3 Effects of the mixture of post-emergence herbicides on the safety, quality of alfalfa and weeds 1. Test materials (1) Field test materials: The tested herbicide combinations and concentration settings are shown in Table 9. The tested alfalfa variety is Zhongcao No. 3 (from the School of Life Sciences, Inner Mongolia University), with a germination rate of 85%; the Chenopodiaceae weed seeds are Chenopodiaceae (harvested from the experimental field in Hohhot City in October 2021), with a germination rate of 25%; the Poaceae weed seeds are Setaria viridis and Broomcorn millet (harvested from the experimental field in Hohhot City in October 2021), with a germination rate of 30%.

[0063] Table 9 Test herbicide combinations and concentrations

[0064] (2) Materials for leaf area determination: Sample alfalfa leaves that had been sprayed with 5% imazamethoate + 10.8% high-efficiency haloxyfop-p-butyl, 24% imazamethoate + 10.8% high-efficiency haloxyfop-p-butyl, 50% promethazine + 10.8% high-efficiency haloxyfop-p-butyl, 30% 2,4-D butyrate sodium salt + 10.8% high-efficiency haloxyfop-p-butyl, or treated with manual weeding or clean water for 30 days. Select healthy, disease-free leaves with obvious differences at the fourth node on the stem, rinse the soil off the surface of the samples with sterile water, and gently wipe them clean.

[0065] (3) Nutritional quality test materials: spray 5% imazethapyr + 10.8% high-efficiency haloxyfop-p-butyl (750 + 225 mL / hm 2 )、30% 2,4-D butyrate sodium salt + 10.8% high-efficiency haloxyfop-p-butyl (1687.5 + 337.5 mL / hm 2 The alfalfa was sampled after being treated with the combination of ) and clean water for 30 days, dried at 65℃ in the laboratory until the mass was constant, crushed, sieved, and sealed and dried for storage.

[0066] 2. Field test methods The experiment was conducted in the experimental field of Hohhot, Inner Mongolia Autonomous Region. The experimental field was weeded once with herbicides before treatment. The medium and large weeds in the experimental field were removed before the experiment to ensure that the weed level was consistent before the experiment and there was no significant difference between the plots. Watering before sowing, alfalfa, quinoa, and grass weed seeds were mixed evenly, and the alfalfa sowing rate was 300 seeds / m 2 , quinoa seeding rate 400 seeds / m 2 , the sowing rate of grass weed seeds after mixing is 200 seeds / m 2 , row spacing of 30cm, row sowing, and field management followed the conventional field management standards. A total of 14 treatments were set up in the experiment, including 12 different combinations of test agents and 2 control treatments of spraying water and manual weeding. The agent group was a mixture of two agents, diluted with water and sprayed, and the spraying rate of each agent combination after dilution with water was 300L / hm 2 The clean water group was sprayed with clean water without weeding, and the spraying amount of clean water was 300L / hm 2, the manual weeding group did not spray clear water but carried out manual weeding (Table 9). The alfalfa plot area was 1 m × 1 m, and a randomized complete block experimental design was adopted. Three 0.25 m sampling points were selected in each plot. 2 For each herbicide combination, three concentration gradient combinations of the optimal concentration, 25% reduction, and 50% reduction were set. On August 11, 2023 (at the three-leaf stage of weeds), it was sprayed once. On the same day, the manual weeding group carried out manual weeding treatment, and the clear water group sprayed clear water.

[0067] 3. Leaf area measurement method: The leaf area was measured using a YMJ-B leaf area meter.

[0068] 4. Nutritional quality measurement method: Nutritional analysis was determined using conventional laboratory analysis methods. Referring to GB / T6432-2018, a FOSS Kjeltec 8400 automatic Kjeldahl nitrogen analyzer was used to determine the crude protein content; a FIWE Raw Fiber Extractors semi-automatic cellulose analyzer was used to determine neutral detergent fiber (NDF) and acid detergent fiber (ADF); the relative feeding value (RFV) was calculated.

[0069] 5. Nutritional quality measurement indicators and methods: Calculate the contents of crude protein, neutral detergent fiber (NDF), and acid detergent fiber (ADF). According to the contents of NDF and ADF, the relative feeding value (RFV) was calculated using the following formula: RFV = DMI × DDM / 1.29 DMI = 120 / NDF DDM = 88.9 - 0.779 × ADF In the formula: DMI is the dry matter intake, and DDM is the digestible dry matter.

[0070] 6. Alfalfa safety analysis: The same method as in Example 1 was used for safety observation.

[0071] By evaluating the effects of different concentrations of herbicide mixtures for foliar treatment on the plant height, fresh weight, and dry weight of alfalfa, the results are shown in Table 10. The results show that the combination concentrations of 5% imazethapyr + 10.8% haloxyfop-P-methyl, 50% prometryn + 10.8% haloxyfop-P-methyl, and 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl are negatively correlated with the plant height of alfalfa, and the combination concentration of 24% imazapic + 10.8% haloxyfop-P-methyl is positively correlated with the plant height of alfalfa; the combination concentrations of each foliar treatment herbicide mixture are positively correlated with the fresh weight and dry weight of alfalfa.

[0072] Table 10 Effects of different concentrations of herbicide mixtures on the plant height, fresh weight, and dry weight of alfalfa

[0073] Note: MZ+GX is 5% imazethapyr + 10.8% haloxyfop-P-methyl, JM+GX is 24% imazapic + 10.8% haloxyfop-P-methyl, PC+GX is 50% prometryn + 10.8% haloxyfop-P-methyl, DB+GX is 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl; the statistical data results are shown as mean ± standard deviation, and the significance analysis is P<0.05.

[0074] 7. Analysis of weed control effect: The same method as in Example 1 was used to observe the weed control effect.

[0075] (1) Effect of mixing herbicides with different concentrations for foliar treatment on the control efficacy of weed plants By evaluating the effect of mixing herbicides with different concentrations for foliar treatment on the control efficacy of Chenopodiaceae weeds and Gramineae weeds, the results are shown in Table 11. The results show that the control efficacy of weed plants in different herbicide combinations increases with the increase of the application dose.

[0076] Table 11 Effect of mixing herbicides with different concentrations on the control efficacy of weed plants

[0077] Note: MZ+GX is 5% imazethapyr + 10.8% haloxyfop-P-methyl, JM+GX is 24% imazapic + 10.8% haloxyfop-P-methyl, PC+GX is 50% prometryn + 10.8% haloxyfop-P-methyl, DB+GX is 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl; the statistical data results are shown as mean ± standard deviation, and the significance analysis is P<0.05.

[0078] (2) Effect of mixing herbicides with different concentrations for foliar treatment on the fresh weight control efficacy of weeds By evaluating the effect of mixing herbicides with different concentrations for foliar treatment on the fresh weight control efficacy of Chenopodiaceae weeds and Gramineae weeds, the results are shown in Table 12. The results show that the fresh weight control efficacy of weeds in different herbicide combinations increases with the increase of the application dose.

[0079] Table 12 Effect of mixing herbicides with different concentrations on the fresh weight control efficacy of weeds

[0080] Note: MZ+GX is 5% imazethapyr + 10.8% haloxyfop-P-methyl, JM+GX is 24% imazapic + 10.8% haloxyfop-P-methyl, PC+GX is 50% prometryn + 10.8% haloxyfop-P-methyl, DB+GX is 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl; the statistical data results are shown as mean ± standard deviation, and the significance analysis is P<0.05.

[0081] 8. Alfalfa Leaf Area Analysis By evaluating the effects of herbicide mixtures with different concentrations on the leaf size of alfalfa through stem and leaf treatments, the results are as Figure 1 shown in Table 13. The results indicate that different combinations of herbicides for stem and leaf treatments have different effects on the leaf size of alfalfa, and different concentrations of the same combination also have different effects on the leaf size of alfalfa. After applying 5% imazethapyr + 10.8% haloxyfop-P-methyl and 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl, the leaf area of alfalfa increased significantly.

[0082] Table 13 Effects of Herbicide Mixtures with Different Concentrations on the Leaf Size of Alfalfa

[0083] Note: MZ+GX is 5% imazethapyr + 10.8% haloxyfop-P-methyl, JM+GX is 24% imazapic + 10.8% haloxyfop-P-methyl, PC+GX is 50% prometryn + 10.8% haloxyfop-P-methyl, DB+GX is 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl; the statistical data results are shown as mean ± standard deviation, and the significance analysis P<0.05.

[0084] Combining the safety, control efficacy and leaf area of herbicide mixtures with different concentrations for stem and leaf treatments, a total of 2 safe and efficient herbicide combinations were screened out, namely: 5% imazethapyr + 10.8% haloxyfop-P-methyl (750 + 225 mL / hm 2 ) and 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl (1687.5 + 337.5 mL / hm 2 ), which can achieve a 50% and 25% reduction respectively.

[0085] 9. Alfalfa Nutritional Quality Analysis By evaluating the effects of the 2 combinations of herbicide mixtures for stem and leaf treatments obtained through screening on the nutritional quality of alfalfa, the results are shown in Table 14. The results indicate that after applying the 2 combinations of herbicide mixtures for stem and leaf treatments, the crude protein content increased significantly, increasing by 3.03 - 4.13% compared with the water treatment; the acid detergent fiber content decreased significantly, decreasing by 4.44% - 16.11% compared with the water treatment; the neutral detergent fiber content decreased significantly, decreasing by 2.22% - 5.74% compared with the water treatment; the relative feeding value of alfalfa increased significantly, increasing by 3.02% - 8.88% compared with the water treatment.

[0086] Table 14 Effects of Herbicide Mixtures with Different Concentrations on the Nutritional Quality of Alfalfa

[0087] Note: MZ + GX is 5% imazethapyr + 10.8% haloxyfop-P-methyl, and DB + GX is 30% sodium 2,4-D butyrate + 10.8% haloxyfop-P-methyl; the statistical data results are shown as mean ± standard deviation, and the significance analysis is P < 0.05; the samples were collected 30 days after spraying the herbicide and before the alfalfa budding stage.

[0088] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for controlling weeds in alfalfa fields, characterized in that, The weeds include one or several of Chenopodium serotinum, Setaria viridis, and Panicum miliaceum; The method includes the following steps: spraying a herbicide composition at the 2-5 leaf stage of the weeds; The herbicide composition includes component A and component B. Component A is 5% imazethapyr or 30% sodium 2,4-D butyrate, and component B is 10.8% haloxyfop-P-methyl; When the component A is 5% imazethapyr, the volume ratio of component A to component B is 3 - 4:1; the application rate of the herbicide composition is 975 - 1462.5 mL / hm 2 ; When the component A is 30% sodium 2,4-dichlorophenoxyacetate, the volume ratio of component A to component B is 4-6:1; the application rate of the herbicide composition is 1350-2025 mL / hm 2 .

2. The method according to claim 1, characterized in that, When the component A is 5% imazethapyr, the volume ratio of component A to component B is 10:3, and the application rate of the herbicide composition is 975 mL / hm 2 ; when the component A is 30% sodium 2,4-D butyrate, the volume ratio of component A to component B is 5:1, and the application rate of the herbicide composition is 2025 mL / hm 2 .

3. The method according to claim 1, characterized in that The application frequency of the herbicide composition is 1 time.

4. The method according to claim 1, wherein The preparation method of the herbicide composition includes: mixing component A and component B to obtain the herbicide composition.

5. Use of the method according to any one of claims 1 to 4 in increasing the yield and improving the quality of alfalfa.

6. The application according to claim 5, wherein The variety of the alfalfa includes Zhongcao No.

3.

7. The application according to claim 5, wherein The increase in alfalfa yield includes one or several of increasing the plant height, fresh weight, dry weight, and leaf area of alfalfa.

8. The application according to claim 5, characterized in that, The improvement of alfalfa quality includes one or several of increasing the crude protein content of alfalfa, reducing the acid detergent fiber content, reducing the neutral detergent fiber content, and increasing the relative feeding value.

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