Foliage spraying agent as well as preparation method and application thereof

Abstract

The invention discloses a foliage spraying agent as well as a preparation method and application thereof, and relates to the technical field of agricultural planting. The foliage spraying agent provided by the invention comprises the following raw materials: polyethyleneimine and a water-soluble silicon fertilizer, wherein the addition amount of the polyethyleneimine in the foliage spraying agent is 0.0005 g / L to 0.008 g / L, and the addition amount of the water-soluble silicon fertilizer in the foliage spraying agent is 0.5 mL / L to 5 mL / L; the water-soluble silicon fertilizer is a liquid fertilizer containing nano silicon. And correspondingly. The invention also discloses application of the foliar spraying agent in relieving cadmium toxicity of plants in a cadmium stress environment. The foliage spraying agent provided by the invention can relieve the toxicity of heavy metal cadmium toxicity to plants such as rice, Chinese cabbage and the like, so that the growth inhibition effect of cadmium stress on the plants is reduced, and the biomass and yield of the plants under cadmium toxicity growth are improved.

Description

Technical Field

[0001] This invention relates to the field of agricultural planting technology, and in particular to a foliar spray agent, its preparation method, and its application. Background Technology

[0002] Human activities have exacerbated soil acidification, resulting in large areas of arable land worldwide being acidic. Cadmium (Cd) is a non-essential, highly toxic heavy metal and a widespread environmental pollutant. In nature, it typically exists in the Earth's crust as sulfides and also in ores such as zinc, lead, and copper ores. Cadmium can be released into the environment through natural and anthropogenic factors such as volcanic eruptions, rock weathering, soil erosion, the application of cadmium-containing fertilizers, and sewage sludge. By migrating through farmland soils and water bodies, it severely impacts soil quality and land productivity, adversely affecting plant growth. Furthermore, cadmium toxicity can directly enter crops, accumulating and amplifying through the food chain, transferring to agricultural products, and ultimately entering the human food chain, endangering food safety and human health. Reducing soil cadmium toxicity and minimizing crop absorption of cadmium has long been a challenging problem in agriculture.

[0003] To address the problem of cadmium toxicity in soil, current solutions mostly focus on the following: applying fertilizers such as silicon, boron, magnesium, and organic matter to enhance the plant's antioxidant capacity, and simultaneously increasing the soil pH to reduce the ionic form of cadmium in the soil, thereby decreasing plant absorption of cadmium ions. While these solutions can mitigate the toxic effects of cadmium on plants to some extent, overall effectiveness and long-term practical feedback indicate that their mitigation effect on cadmium toxicity is still insufficient to meet the needs of plants for normal growth and development in cadmium-contaminated soil environments. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a foliar spray that can alleviate the toxicity of heavy metal cadmium to plants such as rice and cabbage, thereby reducing the growth inhibition effect of cadmium stress on plants and increasing the biomass and yield of plants under cadmium toxicity.

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a foliar spray, which is simple to prepare and the foliar spray obtained can alleviate the toxicity of heavy metal cadmium to plants such as rice and cabbage.

[0006] The technical problem to be solved by the present invention is to provide the application of the above-mentioned foliar spray in alleviating cadmium toxicity in plants under cadmium stress.

[0007] To solve the above-mentioned technical problems, the present invention provides a foliar spray agent, wherein the raw materials of the foliar spray agent include polyethyleneimine and water-soluble silicon fertilizer;

[0008] The amount of polyethyleneimine added in the foliar spray is 0.0005 g / L to 0.008 g / L;

[0009] The amount of water-soluble silicon fertilizer added to the foliar spray is 0.5 mL / L to 5 mL / L;

[0010] The water-soluble silicon fertilizer is a liquid fertilizer containing nano-silicon.

[0011] As an improvement to the above technical solution, the polyethyleneimine is branched polyethyleneimine.

[0012] As an improvement to the above technical solution, the branched polyethyleneimine has a density of 1 g / mL to 1.15 g / mL at 25°C and a viscosity of 10000 mPa·s to 20000 mPa·s at 50°C.

[0013] As an improvement to the above technical solution, the amount of nano-silicon added in the water-soluble silicon fertilizer is ≥100g / L.

[0014] Accordingly, the present invention also provides a method for preparing a foliar spray agent, which includes the following steps:

[0015] (1) Disperse polyethyleneimine in water according to the specified ratio to obtain a polyethyleneimine dispersion;

[0016] (2) Add water-soluble silicon fertilizer to the polyethyleneimine dispersion, mix well, and obtain a foliar spray.

[0017] As an improvement to the above technical solution, in step (1), polyethyleneimine is added to water and subjected to ultrasonic treatment and vortex oscillation to completely disperse the polyethyleneimine and obtain a polyethyleneimine dispersion.

[0018] In step (2), water-soluble silicon fertilizer is added to the polyethyleneimine dispersion, and ultrasonic treatment and vortex oscillation are performed to fully combine the polyethyleneimine and nano-silicon to obtain a foliar spray.

[0019] In steps (1) and (2), the power of ultrasonic treatment is 500W to 1000W, the temperature is 20℃ to 37℃, and the frequency of vortex oscillation is 20Hz to 50Hz.

[0020] Accordingly, the present invention also provides the application of foliar sprays in alleviating cadmium toxicity in plants under cadmium stress.

[0021] Accordingly, the present invention also provides the application of foliar sprays in promoting plant biomass increase under cadmium stress.

[0022] Accordingly, the present invention also provides the application of foliar sprays in promoting plant photosynthesis under cadmium stress.

[0023] Preferably, the plants include rice, cabbage, wheat, and corn.

[0024] More preferably, the plant is rice, and the foliar spray is applied to the leaf surface of rice at the tillering stage, the booting stage, and the grain-filling stage, respectively.

[0025] Implementing this invention has the following beneficial effects:

[0026] 1. In response to the problem of cadmium toxicity in soil, this embodiment provides a foliar spray that can endow plant roots and leaves with a certain biomineralization capacity, effectively reduce the absorption of cadmium by plants, reduce the toxicity of heavy metal cadmium to crops such as rice, cabbage, wheat and corn, and achieve the purpose of improving the growth and development and nutritional quality of plants under cadmium stress, and can also improve acidic soil.

[0027] 2. By selecting and using a high-molecular-weight material—branched polyethyleneimine (PEI)—mixed with water-soluble silicon fertilizer, the adsorption capacity of nano-silicon can be further improved. After foliar spraying of crops, better spraying effect can be achieved, further reducing the absorption of cadmium by crops, significantly reducing the inhibitory effect of cadmium stress on crop growth, thereby increasing the growth of crops under cadmium toxicity, promoting the photosynthesis of crops under cadmium toxicity, and thus significantly improving the economic benefits of crops. This is of great significance for crop planting and ensuring food security in cadmium-polluted areas.

[0028] 3. Cadmium stress significantly reduces rice plant height, stem diameter, effective panicles, number of filled grains, thousand-grain weight, root fresh weight, and dry weight. By spraying foliar agents on the leaves during the tillering, booting, and grain-filling stages of rice, the growth-inhibiting effect of cadmium stress can be reduced, effectively restoring plant height and stem diameter, and increasing biomass. Furthermore, foliar spraying under cadmium stress can enhance photosynthesis and chlorophyll content in rice, and spraying during the grain-filling stage can delay rice senescence and increase yield. In conclusion, spraying foliar agents on rice leaves can effectively reduce cadmium absorption by rice, thereby promoting rice growth and improving its nutritional quality. Attached Figure Description

[0029] Figure 1 The image shows the chlorophyll content measurement results of rice during the tillering stage in Example 1 of the present invention.

[0030] Figure 2 This is a graph showing the chlorophyll content measurement results of rice during the booting stage in Example 1 of the present invention;

[0031] Figure 3 This is a graph showing the chlorophyll content measurement results of rice during the grain-filling stage in Example 1 of the present invention;

[0032] Figure 4 This is a graph showing the plant height measurement results of rice at the jointing stage in Example 1 of the present invention;

[0033] Figure 5 This is a graph showing the plant height measurement results of mature rice at harvest time in Example 1 of the present invention;

[0034] Figure 6 This is a graph showing the results of stem diameter measurement of mature rice at harvest time in Example 1 of the present invention. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0036] Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Raw materials whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0037] This embodiment discloses a foliar spray agent, the raw materials of which include polyethyleneimine and water-soluble silicon fertilizer;

[0038] The amount of polyethyleneimine added in the foliar spray is 0.0005 g / L to 0.008 g / L, and exemplary amounts are 0.0005 g / L, 0.001 g / L, 0.002 g / L, 0.003 g / L, 0.004 g / L, 0.005 g / L, 0.006 g / L, 0.007 g / L, and 0.008 g / L, but is not limited thereto;

[0039] The amount of water-soluble silicon fertilizer added to the foliar spray is 0.5 mL / L to 5 mL / L, exemplarily 0.5 mL / L, 1 mL / L, 2 mL / L, 2.5 mL / L, 3 mL / L, 4 mL / L, and 5 mL / L, but not limited thereto;

[0040] The water-soluble silicon fertilizer is a liquid fertilizer containing nano-silicon.

[0041] It is worth noting that spraying foliar agents onto the leaf surface of plants allows polyethyleneimine to induce the deposition of nano-silicon on the cell walls, endowing plants with a certain degree of biomineralization capacity. This reduces the toxicity of cadmium to crops and other plants, thereby mitigating the growth-inhibiting effect of cadmium stress on crops and other plants, promoting plant growth and development under cadmium stress, and increasing chlorophyll content, photosynthetic rate, and yield of crops under cadmium toxicity. Furthermore, foliar sprays can also remediate cadmium-contaminated soil and prevent the transfer of cadmium from plants to grains, ensuring rice yield while reducing the risk of cadmium exceeding standards, which is of great significance for ensuring food security and the ecological environment.

[0042] Specifically, foliar sprays with different concentrations of polyethyleneimine and water-soluble silicon fertilizer can be selected according to different plants. When the plant leaves are non-edible parts, it is preferable to use foliar sprays with higher concentrations of polyethyleneimine and water-soluble silicon fertilizer; when the plant leaves are edible parts, it is preferable to use foliar sprays with lower concentrations of polyethyleneimine and water-soluble silicon fertilizer.

[0043] For example, when applied to plants like rice and wheat where the leaves are not edible, a foliar spray with a polyethyleneimine concentration of 0.001 g / L to 0.008 g / L and a water-soluble silicon fertilizer concentration of 2 mL / L to 5 mL / L can be selected; when applied to plants like cabbage where the leaves are edible, a foliar spray with a polyethyleneimine concentration of 0.0005 g / L to 0.003 g / L and a water-soluble silicon fertilizer concentration of 0.5 mL / L to 2 mL / L can be selected.

[0044] In one embodiment, the polyethyleneimine is a branched polyethyleneimine.

[0045] It is worth noting that common types of polyethyleneimine include linear polyethyleneimine and branched polyethyleneimine. Linear polyethyleneimine is basically insoluble in water at room temperature and has poor binding with nano-silicon. If linear polyethyleneimine is used to prepare foliar sprays, the resulting foliar sprays have little effect on alleviating cadmium toxicity in plants. Therefore, in the preferred embodiment of this invention, branched polyethyleneimine is used to prepare foliar sprays. The molecular chain of branched polyethyleneimine has many branches. This unique molecular structure increases the intermolecular interaction forces, enhances the stability of branched polyethyleneimine in foliar sprays, and allows nano-silicon to fully bind with branched polyethyleneimine. Moreover, the unique molecular structure of branched polyethyleneimine gives it excellent adsorption properties, which can significantly improve the adsorption capacity of nano-silicon, thereby effectively reducing the absorption of cadmium by plants, reducing the growth-inhibiting effect of cadmium stress on plants, promoting the growth and development of plants under cadmium stress, and thus increasing crop yield.

[0046] In one embodiment, the branched polyethyleneimine has a density of 1 g / mL to 1.15 g / mL at 25°C and a viscosity of 10,000 mPa·s to 20,000 mPa·s at 50°C. Branched polyethyleneimine with this density and viscosity range has better adsorption performance and can further reduce the absorption of cadmium by plants.

[0047] More preferably, the branched polyethyleneimine has a density of 1.01 g / mL to 1.08 g / mL at 25°C and a viscosity of 13000 mPa·s to 18000 mPa·s at 50°C. Branched polyethyleneimine with these density and viscosity ranges has better adsorption performance, which is beneficial for further reducing the absorption of cadmium by plants.

[0048] In one embodiment, the amount of nano-silicon added in the water-soluble silicon fertilizer is ≥100g / L. The high content of nano-silicon in the water-soluble silicon fertilizer ensures that the content of nano-silicon in the prepared foliar spray is within a high range. In turn, under the action of polyethyleneimine, nano-silicon can be induced to deposit on the cell wall of plants, thereby alleviating cadmium toxicity in plants such as rice and Chinese cabbage.

[0049] More preferably, the water-soluble silicon fertilizer also contains K2O, and the K2O content is ≥150g / L.

[0050] Accordingly, the present invention also discloses a method for preparing a foliar spray agent, which includes the following steps:

[0051] (1) Disperse polyethyleneimine in water according to the specified ratio to obtain a polyethyleneimine dispersion;

[0052] (2) Add water-soluble silicon fertilizer to the polyethyleneimine dispersion, mix well, and obtain a foliar spray.

[0053] Specifically, in step (1), polyethyleneimine is added to water and subjected to ultrasonic treatment and vortex oscillation to completely disperse the polyethyleneimine, thereby obtaining a polyethyleneimine dispersion.

[0054] Preferably, in step (1), the ultrasonic treatment power is 500W to 1000W, the frequency is 30kHz to 50kHz, and the temperature is 20℃ to 37℃; the vortex oscillation frequency is 20Hz to 50Hz.

[0055] Specifically, in step (2), water-soluble silicon fertilizer is added to the polyethyleneimine dispersion, and ultrasonic treatment and vortex oscillation are performed to fully combine the nano-silicon with PEI to obtain a foliar spray.

[0056] Preferably, in step (2), the power of ultrasonic treatment is 500W to 1000W, the frequency is 30kHz to 50kHz, and the temperature is 20℃ to 37℃; the frequency of vortex oscillation is 20Hz to 50Hz.

[0057] Accordingly, the present invention also discloses the application of the above-mentioned foliar spray in alleviating cadmium toxicity in plants under cadmium stress.

[0058] Specifically, by spraying the foliar spray on the leaf surface of plants, cadmium toxicity in plants under cadmium stress can be alleviated, thereby improving plant quality and yield.

[0059] Preferably, the foliar spray can be applied to the leaf surface of plants at different stages of plant growth; or the foliar spray can be applied to the leaf surface of plants periodically, for example, once every 5 to 30 days.

[0060] Accordingly, the present invention also discloses the application of the above-mentioned foliar spray in promoting plant biomass increase under cadmium stress.

[0061] Specifically, biomass refers to the total amount of organic matter (dry weight) actually surviving per unit area at a certain moment, including the roots, stems, leaves, flowers, fruits, etc. of plants.

[0062] Accordingly, the present invention also discloses the application of the above-mentioned foliar spray in promoting plant photosynthesis under cadmium stress.

[0063] The plants mentioned above are preferably crops, but are not limited to them.

[0064] In one embodiment, the plants include rice, cabbage, wheat, and corn.

[0065] More preferably, the plant is rice. Spraying the foliar spray agent onto the leaf surface of rice plants during the tillering, booting, and grain-filling stages can reduce the growth-inhibiting effect of cadmium stress on rice, promote rice growth under cadmium stress, and increase the chlorophyll content, photosynthetic rate, and yield of rice under cadmium toxicity. Furthermore, it can remediate cadmium-contaminated soil and prevent the transfer of cadmium from the plant to the grains. While ensuring rice yield, it can also reduce the risk of cadmium exceeding standards, which is of great significance for ensuring food security and the ecological environment.

[0066] Specifically, foliar sprays are used to increase plant height, stem diameter, effective panicles, number of grains, thousand-grain weight, fresh root weight, and dry root weight of rice under cadmium toxicity conditions; foliar sprays are used to increase chlorophyll content and photosynthetic rate of rice under cadmium toxicity conditions; and foliar sprays are used to reduce the growth-inhibiting effect of cadmium stress on rice.

[0067] Furthermore, when applying the foliar spray of the present invention to rice, the foliar spray does not require dilution during use. The preferred dosage of the foliar spray is 30L to 100L per acre per application. In addition, for ease of storage, the foliar spray can be prepared as a concentrated solution during preparation. Before use, the concentrated solution can be diluted to obtain a foliar spray with a polyethyleneimine concentration of 0.0005g / L to 0.008g / L and a water-soluble silicon fertilizer concentration of 0.5mL / L to 5mL / L. This foliar spray is then sprayed onto the surface of the rice leaves.

[0068] More preferably, when applied to rice, the concentration of polyethyleneimine in the foliar spray is 0.001 g / L to 0.005 g / L, and the concentration of water-soluble silicon fertilizer is 2 mL / L to 4 mL / L.

[0069] The technical solution of the present invention is further described below through embodiments.

[0070] Example 1

[0071] This embodiment provides a foliar spray agent. The raw materials of the foliar spray agent include branched polyethyleneimine (PEI) and water-soluble silicon fertilizer. The amount of branched polyethyleneimine added in the foliar spray agent is 0.001 g / L, and the amount of water-soluble silicon fertilizer added is 2.5 mL / L.

[0072] In this embodiment, the branched polyethyleneimine (PEI) was purchased from Sigma Reagents, with a quality level of 200, a density of 1.030 g / ml at 25°C, impurities ≤1%, and a viscosity of 13000~18000 (50°C).

[0073] The water-soluble silicon fertilizer selected is the Sitingnuo medium-element water-soluble fertilizer product provided by Foshan Zhibao Ecological Technology Co., Ltd. "Sitingnuo" is made from water-soluble nano silicon as raw material, with added organic matter and inorganic nutrients. Among them, Si≥100g / L; K2O≥150g / L; pH: 9.5~11.5; Na≤10g / L. The registration certificate number of the Ministry of Agriculture and Rural Affairs is: Nongfei (2018) Zhunzi 9209.

[0074] The preparation method of the foliar spray in this embodiment is as follows:

[0075] (1) Add 0.08g of branched polyethyleneimine (PEI) to 0.8L of pure water to prepare a PEI solution with a concentration of 0.1g / L. Sonicate (40kHz, 5min) and vortex (20Hz, 10min) at 25℃ to completely dissolve and disperse the branched polyethyleneimine to obtain a polyethyleneimine dispersion.

[0076] (2) Add 200 mL of water-soluble silicon fertilizer to the polyethyleneimine dispersion in step (1), and perform ultrasonic treatment (40 kHz, 5 min) and vortex oscillation (20 Hz, 10 min) at 25 ℃ to obtain a foliar spray concentrate. The concentration of branched polyethyleneimine in the concentrate is 0.08 g / L, and the concentration of water-soluble silicon fertilizer is 200 mL / L. Store for later use.

[0077] (3) Dilute the foliar spray concentrate 80 times to obtain a foliar spray with a branched polyethyleneimine concentration of 0.001 g / L and a water-soluble silicon fertilizer concentration of 2.5 mL / L.

[0078] Example 2

[0079] This embodiment provides a foliar spray. The difference between the foliar spray in this embodiment and that in Example 1 is that the amount of branched polyethyleneimine added in the foliar spray of Example 2 is 0.003 g / L, and the amount of water-soluble silicon fertilizer added is 2.5 mL / L.

[0080] Example 3

[0081] This embodiment provides a foliar spray. The difference between the foliar spray in this embodiment and that in Example 1 is that the amount of branched polyethyleneimine added in the foliar spray of Example 3 is 0.005 g / L, and the amount of water-soluble silicon fertilizer added is 2.5 mL / L.

[0082] Comparative Example 1

[0083] This comparative example provides a silicon fertilizer spray, which is composed of water-soluble silicon fertilizer and water (i.e., does not contain branched polyethyleneimine). The concentration of water-soluble silicon fertilizer in the silicon fertilizer spray of Comparative Example 1 is 2.5 mL / L.

[0084] The preparation method of the silicon fertilizer spray in Comparative Example 1 is as follows: Take 10 mL of water-soluble silicon fertilizer, dilute it with water 400 times to obtain the silicon fertilizer spray.

[0085] Application Example 1

[0086] This application example uses rice (Oryza sativa) as the experimental material. Rice seeds were washed with pure water for 1 minute, then disinfected with a 5% sodium hypochlorite solution for 30 minutes, and then washed with pure water 5-8 times until the rice seeds were odorless. The rice seeds were sown in petri dishes containing sterilized filter paper. After germination for 7 days, they were transferred to seedling trays. After one week of growth, they were transplanted into Cd-contaminated soil. The Cd-contaminated soil was collected from a typical cadmium-contaminated soil in a rural area of ​​Yingde City, Guangdong Province, South China, at a depth of approximately 20 cm. The soil pH was maintained at 6.5, with total cadmium at 0.62 and available cadmium at 0.35. Green plastic buckets (30 cm in diameter at the top, 20 cm in diameter at the bottom, and 22 cm in height) were used for planting. Each bucket contained a treatment label (written with the treatment number using a thick-tipped oil-based pen), and two rice plants were planted in each bucket.

[0087] This application example was designed with four treatment groups and one control group. The four treatment groups were treatment 1, treatment 2, treatment 3, and treatment 4. Each treatment had three replicates, for a total of 15 potted plants, which were randomly placed and protected in rows. Among them:

[0088] Control group (CK): Conventional fertilization (i.e., 30 kg of 40% compound fertilizer + 7.5 kg of urea + 5 kg of potassium chloride per mu), without the application of other reagents;

[0089] Treatment 1 (T1): Conventional fertilization + silicon fertilizer spray of Comparative Example 1 (water-soluble silicon fertilizer concentration of 2.5 mL / L, without PEI added);

[0090] Treatment 2 (T2): Conventional fertilization + foliar spray of Example 1 (PEI concentration of 0.001 g / L, water-soluble silicon fertilizer concentration of 2.5 mL / L);

[0091] Treatment 3 (T3): Conventional fertilization + foliar spray of Example 2 (PEI concentration of 0.003 g / L, water-soluble silicon fertilizer concentration of 2.5 mL / L);

[0092] Treatment 4 (T4): Conventional fertilization + foliar spray of Example 3 (PEI concentration of 0.005 g / L, water-soluble silicon fertilizer concentration of 2.5 mL / L);

[0093] Select seedlings of uniform growth and transplant them into pots, two seedlings per pot. Spray an appropriate amount of water daily to keep the soil moist. Treatments 1, 2, 3, and 4 were applied to the leaves of rice at the tillering, jointing, booting, and grain-filling stages, respectively, with the same amount of spray applied to each rice plant each time. Samples were taken for measurement and analysis.

[0094] Growth parameter measurement and analysis

[0095] 1. Results of agronomic trait determination

[0096] Two replicates were taken from each treatment group. Before sampling, plant stem height and chlorophyll content were measured after foliar spraying. Sampling was conducted again at rice maturity to measure physiological indicators such as plant height, stem diameter, effective panicles, number of filled grains, and thousand-grain weight. Two intact rice roots were collected and their fresh weight recorded. The roots were then dried at 70℃ until constant weight, and the dry weight was measured.

[0097] Specifically, the results of the determination of agronomic traits of rice after maturity in this application embodiment are shown in Table 1 below.

[0098] Table 1. Results of agronomic traits of rice after maturity

[0099]

[0100] Table 1 shows that the biomass of all agronomic traits of rice increased to some extent after foliar spraying. Calculations show that, compared with the control group, the plant height of rice in treatments 1, 2, 3, and 4 increased by 6.11%, 8.21%, 16.42%, and 11.65%, respectively; the number of grains per panicle increased by 10.82%, 47.86%, 93.17%, and 46.87%, respectively; the number of effective panicles increased by 7.22%, 33.3%, 57.22%, and 42.78%, respectively; and the number of filled grains increased by [missing data]. The percentages of rice biomass increases were 6.4%, 50.4%, 113.6%, and 48.1%, respectively; the thousand-grain weight increased by 1.4%, 3.6%, 7.7%, and 4.3%; the root fresh weight increased by 4.5%, 13.6%, 26.3%, and 19.9%; the root dry weight increased by 6.9%, 23.1%, 40.5%, and 25%; and the total yield increased by 7.2%, 12.3%, 40.5%, and 15.9%, respectively. Furthermore, compared to treatment 1 which involved spraying silicon fertilizer, treatments 2, 3, and 4, which involved spraying foliar fertilizer, showed more significant increases in the biomass of various agronomic traits of rice.

[0101] 2. Results of chlorophyll content determination in rice during the tillering stage

[0102] Specifically, Figure 1 This figure shows the chlorophyll content measurement results of rice at the tillering stage in the control group (CK), treatment 1 (T1), treatment 2 (T2), treatment 3 (T3), and treatment 4 (T4). Figure 1 It can be concluded that after spraying with a foliar spray containing branched polyethyleneimine (PEI) and nano-silicon in treatments 2, 3 and 4, the chlorophyll content of rice in the tillering stage was significantly increased, with treatment 3 showing the most significant effect.

[0103] 3. Results of chlorophyll content determination in rice during the booting stage

[0104] Figure 2 This is a graph showing the chlorophyll content measurement results of rice during the booting stage in the control group, treatment 1, treatment 2, treatment 3, and treatment 4. Figure 2 It can be concluded that the chlorophyll content of rice in the booting stage was significantly increased after foliar spraying, with treatment 3 showing the most significant effect.

[0105] 4. Results of chlorophyll content measurement in rice during the grain-filling stage

[0106] Figure 3 This is a graph showing the chlorophyll content measurement results of rice during the grain-filling stage in the control group, treatment 1, treatment 2, treatment 3, and treatment 4. Figure 3 It can be concluded that the chlorophyll content of rice during the grain-filling stage was significantly increased after foliar spraying, with treatment 3 showing the most significant effect.

[0107] 5. Results of plant height measurement of rice at the jointing stage

[0108] Figure 4 The graph shows the plant height measurement results of rice at the jointing stage in the control group, treatment 1, treatment 2, treatment 3, and treatment 4. Figure 4 It can be concluded that the plant height of rice at the jointing stage was significantly increased after foliar spraying. Compared with the control group, the height of treatment groups 1, 2, 3, and 4 increased by 7.5%, 9.7%, 12.7%, and 8.1%, respectively, with treatment 3 showing the most significant effect.

[0109] 6. Results of plant height measurement of rice at maturity and harvest

[0110] Figure 5 This is a graph showing the plant height measurement results of rice at maturity and harvest in the control group, treatment 1, treatment 2, treatment 3, and treatment 4. Figure 5 It can be concluded that, compared with the control group, the plant height of rice in the mature harvest treatment groups increased by 6.1%, 8.2%, 16.4%, and 11.6% in treatments 1, 2, 3, and 4, respectively, with treatment 3 showing the most significant effect.

[0111] 7. Results of stem diameter measurement of rice at maturity and harvest.

[0112] Figure 6 This figure shows the results of stem diameter measurement of mature rice in the control group, treatment 1, treatment 2, treatment 3, and treatment 4. Figure 6 It can be concluded that, compared with the control group, the stem diameter of rice in the mature harvest treatment groups increased by 8.7%, 14%, 22.3%, and 14.4% in treatments 1, 2, 3, and 4, respectively, with treatment 3 showing the most significant effect.

[0113] illustrate: Figures 4-6In the table, different lowercase letters in the same column indicate significant differences between treatments at the P<0.05 level.

[0114] The above test results and analysis show that the foliar spray provided by this invention can not only alleviate the impact of heavy metal cadmium on the growth traits of rice and increase yield, but also has a simple application method, strong operability, and significant economic benefits after use. It is of great significance for preventing and controlling soil pollution in high-cadmium areas and ensuring food security. Furthermore, the above test results and analysis show that the foliar spray provided in Example 2 has a relatively better application effect.

[0115] It is understood that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0116] The above are merely preferred embodiments of this application, and only specifically describe the technical principles of this application. These descriptions are only for explaining the principles of this application and should not be construed as limiting the scope of protection of this application in any way. Based on this explanation, any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application, as well as other specific embodiments of this application that can be conceived by those skilled in the art without creative effort, should be included within the scope of protection of this application.

Claims

1. A foliar spray agent, characterized in that, The raw materials for the foliar spray include polyethyleneimine and water-soluble silicon fertilizer; The amount of polyethyleneimine added in the foliar spray is 0.0005 g / L to 0.008 g / L; The amount of water-soluble silicon fertilizer added to the foliar spray is 0.5 mL / L to 5 mL / L; The water-soluble silicon fertilizer is a liquid fertilizer containing nano-silicon.

2. The foliar spray agent according to claim 1, characterized in that, The polyethyleneimine is a branched polyethyleneimine.

3. The foliar spray agent according to claim 2, characterized in that, The branched polyethyleneimine has a density of 1 g / mL to 1.15 g / mL at 25°C and a viscosity of 10,000 mPa·s to 20,000 mPa·s at 50°C.

4. The foliar spray agent according to claim 1, characterized in that, The amount of nano-silicon added in the water-soluble silicon fertilizer is ≥100g / L.

5. A method for preparing a foliar spray, characterized in that, The preparation of the foliar spray agent according to any one of claims 1-4 comprises the following steps: (1) Disperse polyethyleneimine in water according to the specified ratio to obtain a polyethyleneimine dispersion; (2) Add water-soluble silicon fertilizer to the polyethyleneimine dispersion, mix well, and obtain a foliar spray.

6. The method for preparing the foliar spray agent according to claim 5, characterized in that, In step (1), polyethyleneimine is added to water and subjected to ultrasonic treatment and vortex oscillation to completely disperse the polyethyleneimine and obtain a polyethyleneimine dispersion. In step (2), water-soluble silicon fertilizer is added to the polyethyleneimine dispersion, and ultrasonic treatment and vortex oscillation are performed to fully combine the polyethyleneimine and nano-silicon to obtain a foliar spray. In steps (1) and (2), the power of ultrasonic treatment is 500W to 1000W, the temperature is 20℃ to 37℃, and the frequency of vortex oscillation is 20Hz to 50Hz.

7. The application of foliar sprays in alleviating cadmium toxicity in plants under cadmium stress, characterized in that, The foliar spray agent is the foliar spray agent according to any one of claims 1-4.

8. The application of foliar sprays in promoting plant biomass increase under cadmium stress, characterized in that, The foliar spray agent is the foliar spray agent according to any one of claims 1-4.

9. The application of foliar sprays in promoting plant photosynthesis under cadmium stress, characterized in that, The foliar spray agent is the foliar spray agent according to any one of claims 1-4.

10. The application according to claim 6, 7 or 8, characterized in that, The plants include rice, cabbage, wheat, and corn; When the plant is rice, the foliar spray is applied to the leaf surface of rice plants at the tillering stage, booting stage, and grain-filling stage, respectively.

Images