Plant cold-resistant composition as well as preparation method and application thereof

Abstract

The invention relates to the technical field of plant cultivation, and particularly discloses a plant cold-resistant composition and a preparation method thereof.The plant cold-resistant composition is prepared from, by weight, 15-35 parts of willow bark natural extract, 5-10 parts of silicon source, 5-10 parts of molybdenum source, 5-10 parts of selenium source and 5-10 parts of water. The dosage of the silicon source is 1-5 parts by weight of SiO2, the dosage of the molybdenum source is 0.01-0.05 part by weight of Mo, the dosage of the selenium source is 0.01-0.05 part by weight of Se, and the balance is water. According to different types of crops, low-temperature cold damage can be effectively prevented, flexible blending can be performed according to element demand characteristics of different crops, and targeted cold resistance protection is achieved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of plant cultivation, and particularly relates to a plant cold resistance composition and a preparation method and application thereof. BACKGROUND

[0002] Low temperature cold damage is one of the main abiotic stress factors that limit the growth, yield and geographical distribution of crops. Traditional crop cold protection and frost resistance measures, such as mulching and building a shed film, have certain effects, but have the disadvantages of high cost, complicated operation, and being easily affected by environmental conditions. Developing efficient, environmentally friendly and easy-to-use plant cold resistance agents has become a research hotspot in modern agriculture.

[0003] Willow bark is used to prepare cold resistance agents in some prior art (such as CN 112640921 A). However, such plant extract-based solutions still have obvious limitations: first, their cold resistance mechanism is relatively simple and mainly relies on organic active substances, and their effectiveness needs to be further improved; second, the design and verification of existing solutions are usually targeted at specific crops (such as rice), and their formula is fixed and cannot be flexibly adjusted according to the sensitivity and demand differences of different types of crops (such as field crops, vegetable crops, fruit tree crops or other economic crops) for elements, and their universality and effectiveness stability cannot be guaranteed; third, the synergistic effect of multiple functional elements and plant-derived active substances has not been systematically integrated.

[0004] Although the role of trace elements in improving plant cold resistance has been reported, different crops have significant differences in their demand and response to these elements. However, according to the element preference characteristics of crops, the scientific compounding and flexible compounding of willow bark natural extract and multiple functional elements have not been disclosed and verified by prior art.

[0005] In addition, most existing cold resistance agents or foliar fertilizers usually need to add additional chemical surfactants, such as Tween 80, in order to promote leaf absorption. This not only increases the cost and complexity of the formula, but also may introduce new environmental burdens and has the risk of compatibility with other ingredients. SUMMARY

[0006] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a plant cold resistance composition and a preparation method thereof, which can effectively prevent low temperature cold damage according to different types of crops and can be flexibly adjusted according to the element demand characteristics of different crops to achieve targeted cold resistance protection.

[0007] The purpose of the present application is also to provide a plant cold resistance composition and a preparation method thereof, which utilizes its own components to achieve leaf spreading function, thereby reducing or avoiding the addition of additional chemical surfactants.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a plant-based cold-resistant composition comprising a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water, wherein the natural extract of willow bark is used in an amount of 15-35 parts by weight of dry matter; the silicon source is used in an amount of 1-5 parts by weight of SiO2, and the mass concentration of SiO2 in the silicon source is not less than 20%; the molybdenum source is used in an amount of 0.01-0.05 parts by weight of Mo; the selenium source is used in an amount of 0.01-0.05 parts by weight of Se; and the balance is water (by weight).

[0009] The natural extract of willow bark is obtained by water extraction followed by ultrasonic-assisted treatment, and the content of salicin in the natural extract of willow bark is not less than 60%.

[0010] In some embodiments, the natural extract of willow bark is prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder is mixed with deionized water at 50-60 ℃ at a material-to-liquid ratio of 1:12 to 1:15, and the mixture is stirred and extracted at a constant speed for 25-40 min to obtain a mixture. The material-to-liquid ratio is measured in g / mL. The mixture was placed in an ultrasonic device and ultrasonically treated for 20-30 min at a frequency of 20-100 kHz and a power of 100-150 W using pulse mode and ice bath cooling. The ultrasonically treated mixture is then filtered. Centrifuge the filtered mixture, collect the supernatant, and finally concentrate it under low temperature and reduced pressure to 1 / 5 to 2 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0011] In some preferred embodiments, the amount of the natural willow bark extract is 15-25 parts by weight of dry matter, and the ratio of the amount of silicon source (calculated as SiO2), molybdenum source (calculated as Mo), and selenium source (calculated as Se) is 100:(0.5-2):(0.5-2).

[0012] In some preferred embodiments, the silicon source is selected from one or more of potassium silicate, sodium silicate, and organosilicon sol, wherein the particle size of the organosilicon sol is 10-50 nm; the molybdenum source is selected from one or more of sodium molybdate and ammonium molybdate; and the selenium source is selected from one or more of sodium selenite and sodium selenate.

[0013] Another aspect of the present invention provides a method for preparing a plant-based cold-resistant composition, comprising: (1) Preparation of natural extracts from willow bark; (2) The natural extract of willow bark, silicon source, molybdenum source, selenium source and water are mixed in proportion; The willow bark natural extract is used in an amount of 15-25 parts by weight of dry matter, the silicon source is used in an amount of 1-5 parts by weight of SiO2, the molybdenum source is used in an amount of 0.01-0.05 parts by weight of Mo, the selenium source is used in an amount of 0.01-0.05 parts by weight of Se, and the balance is water.

[0014] In some embodiments, the natural extract of willow bark is prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder is mixed with deionized water at 50-60 ℃ at a material-to-liquid ratio of 1:12 to 1:15, and the mixture is stirred and extracted at a constant speed for 25-40 min to obtain a mixture. The material-to-liquid ratio is measured in g / mL. The mixture was placed in an ultrasonic device and ultrasonically treated for 20-30 min at a frequency of 20-100 kHz and a power of 100-150 W using pulse mode and ice bath cooling. The ultrasonically treated mixture is then filtered. Centrifuge the filtered mixture, collect the supernatant, and finally concentrate it under low temperature and reduced pressure to 1 / 5 to 2 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0015] In some preferred embodiments, the pulse mode is to work for 2 to 5 seconds and pause for 1 to 2 seconds; the temperature of the ice bath cooling is 4 to 10 °C.

[0016] In some preferred embodiments, the ultrasonically treated mixture is filtered through a 100-200 mesh sieve.

[0017] In some preferred embodiments, the filtered mixture is centrifuged at 8000~10000 r / min for 15~30 min, the supernatant is collected, and finally concentrated under reduced pressure at 50~55 ℃ to 1 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0018] In some preferred embodiments, the silicon source is selected from one or more of potassium silicate, sodium silicate, and organosilicon sol, and the particle size of the organosilicon sol is 10~50 nm; The organosilicon sol is prepared by the following method: Industrial water glass is passed through a strongly acidic cation exchange resin to remove sodium ions (Na). + Impurities such as ) are removed to obtain an active silicic acid solution; Under ultrasonic assistance, the active silicic acid solution was used as the silicon source, and dilute ammonia water was used as the alkali source. The polymerization reaction was carried out at 60~70 °C and under uniform stirring conditions. The pH value of the reaction system was controlled between 9.0 and 10.5 to form a monodisperse silica sol primary product. The initial silica sol product was concentrated by cyclic filtration using an ultrafiltration membrane, and chitosan quaternary ammonium salt solution was added dropwise as a stabilizer during the process to obtain nano-silica sol.

[0019] In another aspect, the present invention provides an application of a plant cold-resistant composition in crop cultivation, wherein the plant cold-resistant composition is sprayed onto the leaves of crops 3 to 7 days before the arrival of a cold wave.

[0020] In some embodiments, 3 to 7 days before the arrival of a cold wave, the plant cold-resistant composition is diluted 100 to 200 times and applied evenly to the leaves of crops by manual spraying; or diluted 10 to 20 times and applied evenly to the leaves of crops by drone spraying.

[0021] The plant-based cold-resistant composition of the present invention can be flexibly formulated according to the elemental requirements of the target crop to achieve targeted and efficient cold-resistant protection.

[0022] For crops with high silicon requirements (such as rice and corn), the amount of silicon source (calculated as SiO2) in the composition can be appropriately increased, for example, to the upper limit of the dosage range (5 parts); for molybdenum-sensitive crops (such as tea trees and citrus), the amount of molybdenum source (calculated as Mo) in the composition can be appropriately increased, for example, to the upper limit of the dosage range (0.05 parts); for crops with strong selenium accumulation capacity or when used as a selenium supplement (such as Isatis indigotica and okra), the amount of selenium source (calculated as Se) in the composition can be appropriately increased, for example, to the upper limit of the dosage range (0.05 parts).

[0023] The dosage adjustments of the above elements are all made within the total ratio range described in this invention, thereby achieving precise and efficient cold resistance for different crops based on a universal formula.

[0024] The beneficial effects of this invention are: This invention provides a plant-based cold-resistant composition. The main component is a natural extract of willow bark prepared by low-temperature water extraction combined with ultrasound assistance, scientifically compounded with functional elements such as silicon, molybdenum, and selenium. This composition significantly enhances the overall cold resistance of crops through the synergistic effect of organic active substances and inorganic nutrients. Furthermore, it can be flexibly adjusted according to the elemental requirements of different crops to achieve targeted cold protection, as detailed below: (I) Innovative Extraction Method, Safe and Highly Active: This invention employs a low-temperature water extraction-ultrasound-assisted method to replace traditional organic solvent methods (such as ethanol-butanediol mixed extraction) for preparing natural extracts from willow bark. This method avoids the risk of organic solvent residue, making it more environmentally friendly and safer. Simultaneously, the ultrasonic cavitation effect can more efficiently break down cell walls, maximizing the extraction of active substances such as salicin, phenols, and polysaccharides from willow bark. Furthermore, the low-temperature conditions effectively protect the bioactivity of heat-sensitive components.

[0025] (II) Synergistic Effect of Multiple Mechanisms on Cold Resistance: This invention is the first to scientifically combine a natural compound extract of willow bark with multiple functional elements such as silicon, molybdenum, and selenium. The natural extract of willow bark acts as an organic signaling substance to activate the plant's systemic resistance; silicon is deposited in the cell wall and cuticle, enhancing mechanical strength and water retention; molybdenum plays a key role in regulating nitrogen metabolism and the synthesis of antioxidant enzymes; and selenium enhances the activity of glutathione peroxidase, effectively scavenging free radicals. Through the synergistic effect of these four elements via organic induction, inorganic nutrition, physical barriers, and biochemical antioxidant pathways, a leapfrog improvement in cold resistance is achieved, with effects far superior to simple combinations of single or a few components.

[0026] (III) Flexible and adjustable formula with wide crop applicability: This invention can provide significant cold resistance for different crops (such as rice, vegetables, fruit trees, tea trees, etc.).

[0027] (iv) Low application cost and environmentally friendly: This invention uses silica sol as the silicon source. Its nanoparticles naturally possess the physical functions of reducing surface tension and enhancing leaf spread and adhesion, realizing the integration of fertilizer and adjuvant. This allows the composition of this invention to achieve excellent leaf absorption efficiency without the need for additional chemical surfactants, simplifying the formulation and reducing overall cost and environmental residue risks. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail below. This 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 this invention.

[0029] 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.

[0030] In a first aspect, the present invention provides a plant-based cold-resistant composition comprising a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water.

[0031] The willow bark natural extract is used in an amount of 15-35 parts by weight of dry matter; the silicon source is used in an amount of 1-5 parts by weight of SiO2; the molybdenum source is used in an amount of 0.01-0.05 parts by weight of Mo; the selenium source is used in an amount of 0.01-0.05 parts by weight of Se; and the remainder is water (by weight). After mixing the above components, water is added to bring the total to 100 parts, thus obtaining the concentrated plant-based cold-resistant composition of the present invention. It should be noted that, unless otherwise specified, all amounts mentioned in the present invention are by weight, and all compositions are concentrated solutions.

[0032] The natural extract of willow bark is obtained by low-temperature water extraction followed by ultrasonic-assisted treatment, and the content of salicin in the natural extract of willow bark is not less than 60%.

[0033] The mass concentration of SiO2 in the silicon source is not less than 20%.

[0034] In some preferred embodiments, the amount of the natural willow bark extract is 15-25 parts by weight of dry matter, and the ratio of the silicon source (calculated as SiO2), molybdenum source (calculated as Mo), and selenium source (calculated as Se) is 100:(0.5-2):(0.5-2), more preferably 100:1:1.

[0035] In some preferred embodiments, the silicon source is selected from one or more of potassium silicate, sodium silicate, and organosilica sol; the molybdenum source is selected from one or more of sodium molybdate and ammonium molybdate; and the selenium source is selected from one or more of sodium selenite and sodium selenate. From the perspective of reducing the total electrolyte concentration in the composition and improving the chemical stability of the system, the present invention provides the following preferred component combinations: More preferably, the molybdenum source is ammonium molybdate. This effectively avoids the introduction of Na without changing the effect. + This improves the stability of the system.

[0036] Based on this, the silicon source is preferably an organosilicon sol. This not only avoids the Na+ introduced by sodium silicate... + Its nano-properties can also provide silicon nutrition and leaf spreading function at the same time, which helps to replace traditional surfactants.

[0037] Although sodium selenite and sodium selenate introduce Na... + However, given their versatility, effectiveness, and cost advantages in agricultural applications, they remain the most realistic and feasible selenium sources currently available. By prioritizing the aforementioned sodium-free or low-sodium silicon and molybdenum sources, the total electrolyte concentration of the system can be significantly reduced. Those skilled in the art will understand that if other forms of selenium sources (such as nano-selenium, organic selenium, etc.) with comparable cost and proven effectiveness can be obtained, they should also fall within the scope of protection of this invention.

[0038] The particle size of the organosilicon sol is 10-50 nm. As a basic implementation, a silica sol with a particle size in the range of 10-15 nm can be selected; as a more preferred implementation, a silica sol with a particle size in the range of 20-40 nm prepared by a specific sodium-free process can be selected, which shows better effects in terms of synergistic effect with natural willow bark extract and system stability.

[0039] The organosilicon sol is prepared by the following method, with the specific steps as follows: (1) Ion exchange purification: Industrial water glass is passed through a strongly acidic cation exchange resin to remove Na. + Impurities were removed to obtain an active silicic acid solution; (2) Controlled polymerization growth: Under ultrasonic assistance, the active silicic acid solution is used as the silicon source and dilute ammonia water is used as the alkali source. The polymerization reaction is carried out at 60~70 °C and under uniform stirring conditions. The pH value of the reaction system is controlled between 9.0 and 10.5 to induce the directional and uniform condensation of silicic acid molecules to form a monodisperse silica sol primary product. (3) Membrane concentration and stabilization: The initial silica sol product is concentrated by ultrafiltration membrane and chitosan quaternary ammonium salt solution is added dropwise as a stabilizer to obtain high-purity, narrow-distribution nano silica sol.

[0040] Preferably, the modulus of the industrial water glass is 3.0 to 3.4.

[0041] Preferably, the ultrasonic frequency for the controllable polymerization growth is 20~100 kHz, and the ultrasonic power is 100~300 W.

[0042] Preferably, the concentration of the dilute ammonia water is 5% to 10%, and the stirring speed of the polymerization reaction is 500 to 800 rpm.

[0043] Preferably, the ultrafiltration membrane has a molecular weight cutoff of 5-100 kDa, and the chitosan quaternary ammonium salt solution accounts for 0.5%-1.0% of the mass of the organosilicon sol.

[0044] This invention utilizes the dual functions of the organosilicon sol prepared by this method: firstly, it directly enhances crop stress resistance as a silicon nutrient element; secondly, its nano-properties endow the composition with excellent high spreading and high adhesion properties, which can completely replace or reduce the use of traditional chemical surfactants.

[0045] In some embodiments, the natural extract of willow bark is prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder is mixed with deionized water at 50-60 ℃ at a material-to-liquid ratio of 1:12 to 1:15, and the mixture is stirred and extracted at a constant speed for 25-40 min to obtain a mixture. The material-to-liquid ratio is measured in g / mL. The mixture was placed in an ultrasonic device and ultrasonically treated for 20-30 min at a frequency of 20-100 kHz and a power of 100-150 W using pulse mode and ice bath cooling. The ultrasonically treated mixture is then filtered. Centrifuge the filtered mixture, collect the supernatant, and finally concentrate it under low temperature and reduced pressure to 1 / 5 to 2 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0046] In some preferred embodiments, the pulse mode is to work for 2-5 seconds and pause for 1-2 seconds, more preferably, to work for 2-4 seconds and pause for 1-2 seconds; the temperature of the ice bath cooling is 4-10 ℃, more preferably 5-8 ℃.

[0047] In some preferred embodiments, the ultrasonically treated mixture is filtered through a 100-200 mesh sieve, more preferably through a 100-150 mesh sieve.

[0048] In some preferred embodiments, the filtered mixture is centrifuged at 8000-10000 r / min for 15-30 min, the supernatant is collected, and finally concentrated under reduced pressure at 50-55 °C to 1 / 5 of the original volume to obtain a concentrated willow bark natural extract. More preferably, the filtered mixture is centrifuged at 8000-9000 r / min for 15-20 min, the supernatant is collected, and finally concentrated under reduced pressure at 50-53 °C to 1 / 5 of the original volume to obtain a concentrated willow bark natural extract.

[0049] This invention employs a low-temperature water extraction-ultrasound-assisted method to replace traditional organic solvent methods (such as ethanol-butanediol mixed extraction) for preparing natural extracts from willow bark. This method avoids the risk of organic solvent residue, is more environmentally friendly and safer, and the ultrasonic cavitation effect can more efficiently break down cell walls, maximizing the extraction of active substances such as salicin, phenols, and polysaccharides from willow bark. Furthermore, the low-temperature conditions effectively protect the bioactivity of heat-sensitive components. The extraction process uses a staged temperature control strategy. First, water extraction is performed at 50-60 °C to balance extraction efficiency and activity protection. Subsequently, during ultrasonic treatment, the temperature is maintained at 4-10 °C using an ice bath to effectively counteract the heat generated by ultrasonic energy conversion, preventing the inactivation of heat-sensitive active components due to localized high temperatures, thus achieving a balance between high efficiency and high activity yield.

[0050] Another aspect of the present invention provides a method for preparing a plant-based cold-resistant composition, comprising: (1) Preparation of natural extracts from willow bark; (2) The natural extract of willow bark, silicon source, molybdenum source, selenium source and water are mixed in proportion; The natural extract of willow bark mentioned in step (1) is preferably prepared by the low-temperature water extraction-ultrasound-assisted method described above, and the specific steps are the same as those disclosed in the "Preparation of Natural Extract of Willow Bark" section of the specification [Specific Embodiments].

[0051] The willow bark natural extract is used in an amount of 15-35 parts by weight of dry matter, and the content of salicin in the willow bark natural extract is not less than 60%; the silicon source is used in an amount of 1-5 parts by weight of SiO2; the molybdenum source is used in an amount of 0.01-0.05 parts by weight of Mo; the selenium source is used in an amount of 0.01-0.05 parts by weight of Se; and the balance is water.

[0052] In another aspect, the present invention provides an application of a plant cold-resistant composition in crop cultivation, wherein the plant cold-resistant composition is sprayed onto the leaves of crops 3 to 7 days before the arrival of a cold wave.

[0053] In some embodiments, 3 to 7 days before the arrival of a cold wave, the plant cold-resistant composition is diluted 100 to 200 times and applied evenly to the leaves of crops by manual spraying; or diluted 10 to 20 times and applied evenly to the leaves of crops by drone spraying.

[0054] Three to seven days before the arrival of a cold snap, dilute this cold-resistant composition 100 to 200 times and apply it evenly to the crop leaves by manual spraying, or dilute it 10 to 20 times and apply it evenly to the crop leaves by drone spraying. The dosage of the undiluted solution is 500 mL per acre. Users can flexibly adjust the ratio of silicon, molybdenum, selenium, and other elements within the above range according to the characteristics of different crops (such as rice and corn, which have high silicon requirements; tea trees and citrus, which are sensitive to molybdenum; and isatis root, cabbage, and okra, which are representative of high-selenium crops).

[0055] The technical solution of the present invention will be further described below with reference to specific embodiments and comparative examples.

[0056] Example 1 A plant-based cold-resistant composition comprises a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water. The natural extract of willow bark is used in an amount of 15 parts by weight of dry matter. The silicon source is selected from potassium silicate, and is used in an amount of 2 parts by weight of SiO2. The molybdenum source is selected from ammonium molybdate, and is used in an amount of 0.01 parts by weight of Mo. The selenium source is selected from sodium selenite, and is used in an amount of 0.01 parts by weight of Se. The remainder is water, made up to 100 parts.

[0057] The natural extract of willow bark is prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder was mixed with 50 °C deionized water at a ratio of 1:12 and stirred at a constant speed for 25 min to obtain a mixture. The unit of measurement for the ratio of material to liquid is g / mL. The mixture was placed in an ultrasonic device and cooled in a pulse mode and an ice bath. The pulse mode was operated for 2 seconds and paused for 1 second. The ice bath cooling temperature was 4 ℃. The ultrasonic treatment was carried out for 20 min at a frequency of 20 kHz and a power of 100 W. The ultrasonically treated mixture was filtered through a 100-mesh sieve. The filtered mixture was centrifuged at 8000 r / min for 15 min, the supernatant was collected, and finally concentrated under reduced pressure at 50 ℃ to 1 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0058] Example 2 A plant-based cold-resistant composition comprises a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water. The natural extract of willow bark is used in an amount of 25 parts by weight of dry matter. The silicon source is selected from sodium silicate, and is used in an amount of 2 parts by weight of SiO2. The molybdenum source is selected from ammonium molybdate, and is used in an amount of 0.04 parts by weight of Mo. The selenium source is selected from sodium selenate, and is used in an amount of 0.04 parts by weight of Se. The remainder is water, to a total of 100 parts.

[0059] The natural extract of willow bark is prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder was mixed with 55 °C deionized water at a ratio of 1:15 and extracted by stirring at a constant speed for 35 min to obtain a mixture. The unit of measurement for the ratio of material to liquid is g / mL. The mixture was placed in an ultrasonic device and subjected to pulse mode and ice bath cooling. The pulse mode consisted of 4 seconds of operation followed by 2 seconds of pause. The ice bath cooling temperature was 8 ℃. The ultrasonic treatment was carried out for 25 min at a frequency of 80 kHz and a power of 150 W. The ultrasonically treated mixture was filtered through a 200-mesh sieve. The filtered mixture was centrifuged at 10,000 r / min for 30 min, the supernatant was collected, and finally concentrated under reduced pressure at 55 °C to 1 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0060] Example 3 A plant-based cold-resistant composition comprises a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water. The natural extract of willow bark is used in an amount of 25 parts by weight of dry matter. The silicon source is selected from organosilicon sol and is used in an amount of 3 parts by weight of SiO2. The molybdenum source is selected from ammonium molybdate and is used in an amount of 0.03 parts by weight of Mo. The selenium source is selected from sodium selenite and is used in an amount of 0.03 parts by weight of Se. The remainder is water, to a total of 100 parts.

[0061] The natural extract of willow bark is prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder was mixed with 60 °C deionized water at a ratio of 1:13 and stirred at a constant speed for 40 min to obtain a mixture. The unit of measurement for the ratio of material to liquid is g / mL. The mixture was placed in an ultrasonic device and subjected to ultrasonic treatment for 30 minutes at a frequency of 100 kHz and a power of 100 W using pulse mode and ice bath cooling. The pulse mode consisted of working for 4 seconds and pausing for 2 seconds. The ice bath cooling temperature was 6 ℃. The ultrasonically treated mixture was filtered through a 200-mesh sieve. The filtered mixture was centrifuged at 9000 r / min for 20 min, the supernatant was collected, and finally concentrated under reduced pressure at 52 ℃ to 1 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0062] The particle size of the organosilicon sol is 10~15 nm.

[0063] Example 4 A plant-based cold-resistant composition comprises a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water. The natural extract of willow bark is used in an amount of 25 parts by weight of dry matter. The silicon source is selected from organosilicon sol and is used in an amount of 3 parts by weight of SiO2. The molybdenum source is selected from ammonium molybdate and is used in an amount of 0.03 parts by weight of Mo. The selenium source is selected from sodium selenite and is used in an amount of 0.03 parts by weight of Se. The remainder is water, to a total of 100 parts.

[0064] The natural extract of willow bark is prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder was mixed with 60 °C deionized water at a ratio of 1:13 and stirred at a constant speed for 40 min to obtain a mixture. The unit of measurement for the ratio of material to liquid is g / mL. The mixture was placed in an ultrasonic device and subjected to ultrasonic treatment for 30 minutes at a frequency of 100 kHz and a power of 100 W using pulse mode and ice bath cooling. The pulse mode consisted of working for 4 seconds and pausing for 2 seconds. The ice bath cooling temperature was 6 ℃. The ultrasonically treated mixture was filtered through a 200-mesh sieve. The filtered mixture was centrifuged at 9000 r / min for 20 min, the supernatant was collected, and finally concentrated under reduced pressure at 52 ℃ to 1 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

[0065] The organosilicon sol has a particle size of 20-40 nm and is prepared by the following method: (1) Ion exchange purification: Industrial water glass with a modulus of 3.0~3.4 is passed through a strong acid cation exchange resin to remove Na. + Impurities were removed to obtain an active silicic acid solution; (2) Controlled polymerization growth: Under the assistance of ultrasonic frequency 40 kHz and power 200 W, the entire active silica solution obtained in step (1) is used as the silicon source, and dilute ammonia water with a concentration of 5%~10% is used as the alkali source. The polymerization reaction is carried out under the conditions of 60~70 ℃ and uniform stirring at 500~800 rpm. By precisely controlling the pH value of the reaction system between 9.0 and 10.5, the silica molecules are induced to directionally and uniformly condense to form a monodisperse silica sol primary product. (3) Membrane concentration and stabilization: The initial silica sol product was concentrated by cyclic filtration using an ultrafiltration membrane with a molecular weight cutoff of 10 kDa. During this process, chitosan quaternary ammonium salt solution was added dropwise as a stabilizer. The chitosan quaternary ammonium salt solution accounted for 0.5%~1.0% of the mass of SiO2, and finally high-purity, narrow-distribution nano silica sol was obtained.

[0066] Example 5 This embodiment provides a cold-resistant composition specifically designed for tea trees.

[0067] A plant-based cold-resistant composition comprises a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water. The natural extract of willow bark is used in an amount of 25 parts by weight of dry matter. The silicon source is selected from organosilicon sol (particle size 20-40 nm), and is used in an amount of 3 parts by weight of SiO2. The molybdenum source is selected from ammonium molybdate, and is used in an amount of 0.05 parts by weight of Mo. The selenium source is selected from sodium selenite, and is used in an amount of 0.03 parts by weight of Se. The remainder is water, to a total of 100 parts.

[0068] The preparation methods for the natural extract of willow bark and organosilicon sol are the same as in Example 4.

[0069] Comparative Example 1 A plant-based cold-resistant composition comprising a silicon source, a selenium source, and water, wherein the silicon source is selected from organosilicon sol and is used in an amount of 3 parts by weight of SiO2; the selenium source is selected from sodium selenite and is used in an amount of 0.03 parts by weight of Se; the remainder is water, which is made up to 100 parts.

[0070] Comparative Example 2 A plant-based cold-resistant composition comprising a silicon source, a molybdenum source, and water, wherein the silicon source is selected from organosilicon sol and is used in an amount of 3 parts by weight of SiO2; the molybdenum source is selected from ammonium molybdate and is used in an amount of 0.03 parts by weight of Mo; the remainder is water, which is made up to 100 parts.

[0071] Comparative Example 3 A plant-based cold-resistant composition comprises a silicon source, a molybdenum source, a selenium source, and water. The silicon source is selected from organosilicon sol, and its amount is 3 parts by weight of SiO2. The molybdenum source is selected from ammonium molybdate, and its amount is 0.03 parts by weight of Mo. The selenium source is selected from sodium selenite, and its amount is 0.03 parts by weight of Se. The remainder is water, which is made up to 100 parts.

[0072] Comparative Example 4 A plant-based cold-resistant composition comprises a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water. The natural willow bark extract is extracted using an organic solvent method, and its amount is 25 parts by weight of dry matter. The silicon source is selected from organosilicon sol, and its amount is 3 parts by weight of SiO2. The molybdenum source is selected from ammonium molybdate, and its amount is 0.03 parts by weight of Mo. The selenium source is selected from sodium selenite, and its amount is 0.03 parts by weight of Se. The remainder is water, made up to 100 parts.

[0073] The extraction method for the willow bark extract includes the following steps: crushing the willow bark, mixing it with a solvent, and extracting for 8 hours; filtering, followed by centrifugation and vacuum concentration to obtain a concentrated natural extract of willow bark. The solvent is a mixture of ethanol, water and butanediol; The amount of water used in the solvent is three times the weight of the willow bark; the ethanol concentration is 75%, and the amount used is 15% of the weight of the added water; the amount of butanediol used is 10% of the weight of the added water.

[0074] The cold-resistant agents obtained in the examples and comparative examples were tested below: (1) Test method: Healthy and uniform seedlings of Isatis indigotica, rice, and tea were selected. 3-7 days before the arrival of a cold snap, the seedlings were sprayed with diluted water (control), and diluted solutions of the cold-resistant compositions from Examples 1-5 and Comparative Examples 1-4 (dilution ratio: 100-200 times for manual spraying, 10-20 times for drone spraying). After spraying, the plants were placed in an artificial climate chamber for low-temperature treatment (4°C, 5 days), and then allowed to return to normal temperature for 3 days. Afterwards, the following indicators were measured: Plant biomass (fresh weight, g): weighed immediately after sampling.

[0075] Leaf relative conductivity (%): Measured by a conductivity meter, reflecting cell membrane stability.

[0076] Leaf malondialdehyde content (μmol / kg): determined by the thiobarbituric acid method, reflecting the degree of lipid peroxidation.

[0077] Each treatment was repeated three times, and data are expressed as mean ± standard deviation. Duncan's multiple comparisons were used for significance analysis. P <0.05), with the same letter indicating no significant difference.

[0078] (2) Test results: Table 1. Effects of different cold-resistant agents on the biomass, relative electrical conductivity of leaves, and malondialdehyde content of seedlings of Isatis indigotica after low-temperature treatment in the examples.

[0079] Table 2. Effects of different cold-resistant agents on the biomass, relative electrical conductivity of leaves, and malondialdehyde content of seedlings of Isatis indigotica after low-temperature treatment in Example 4 and each comparative example.

[0080] Table 3. Effects of different cold-resistant agents on seedling biomass, relative leaf conductivity, and malondialdehyde content in rice after low-temperature treatment in the examples.

[0081] Table 4. Effects of different cold-resistant agents on seedling biomass, relative leaf conductivity, and malondialdehyde content in Example 4 and each comparative example on rice seedling biomass, leaf relative conductivity, and malondialdehyde content after low-temperature treatment.

[0082] Table 5. Effects of different cold-resistant agents on the biomass, relative electrical conductivity of leaves, and malondialdehyde content of tea seedlings after low-temperature treatment in the examples.

[0083] Table 6. Effects of different cold-resistant agents on seedling biomass, relative electrical conductivity of leaves, and malondialdehyde content of tea trees after low-temperature treatment in Example 4 and each comparative example.

[0084] (3) Analysis and discussion Based on the test results of the above embodiments and comparative examples, the specific analysis is as follows: This invention successfully replaces the traditional organic solvent extraction process with an environmentally friendly low-temperature water extraction-ultrasound-assisted method, achieving not only equivalent or better results but also demonstrating multiple additional advantages. First, this method possesses excellent universality and reliability. As shown in Tables 1, 3, and 5, Examples 1-5 (low-temperature water extraction-ultrasound-assisted method) exhibited significant and consistent cold resistance effects on various test crops, including Isatis indigotica, rice, and tea. Its core indicators (biomass, relative conductivity, and malondialdehyde content) were significantly better than the water control, and it reached or significantly surpassed the effects of Comparative Example 4 (organic solvent method) in several key indicators. This fully demonstrates that the low-temperature water extraction-ultrasound-assisted method of this invention is an effective, universal, and green alternative. Crucially, as shown in Table 2, the biomass data variability of Example 4 (low-temperature water extraction-ultrasound-assisted method) was much smaller than that of Comparative Example 4 (organic solvent method) (standard deviation: 0.15 for the former; standard deviation: 1.56 for the latter), demonstrating superior process controllability and quality consistency, providing a key guarantee for its industrial application.

[0085] More importantly, the low-temperature water extraction-ultrasound-assisted process described in this invention, combined with a scientifically formulated and flexible compound, constitutes a complete technical system for precisely enhancing cold resistance. This synergistic effect is not only reflected in its broad applicability to crops but also in its superior performance when targeting specific crops. First, the innovative extraction process lays a high-quality foundation of active substances for efficient cold resistance. As shown in Table 6, under the same formulation design framework, Example 4 (low-temperature water extraction-ultrasound-assisted method) using the process of this invention is significantly better than Comparative Example 4 (organic solvent method) in reducing malondialdehyde content in tea trees. This strongly demonstrates that the green extraction process of this invention can better extract or protect heat-sensitive active substances that are particularly effective for cold resistance in tea trees, ensuring the high efficiency of the composition from the source. Furthermore, based on this high quality, the flexibility of the formulation provides targeted and precise control capabilities. As shown in Tables 5 and 6, based on the willow bark natural extract prepared by the optimized process, Example 5 (high-molybdenum composition) specifically designed for tea trees shows further performance optimization. Compared with Example 4, Example 5 shows a statistically significant additional advantage in significantly reducing malondialdehyde content, a key indicator of oxidative damage. This demonstrates that by adjusting the amount of molybdenum source to the optimal upper limit, this targeted formulation can more effectively activate the antioxidant protection system in tea plants, thereby reducing oxidative damage more efficiently at the molecular level.

[0086] In summary, this invention, through the scientific compounding of natural willow bark extract with silicon, molybdenum, and selenium, and combined with an innovative low-temperature water extraction-ultrasound-assisted preparation process, can obtain a plant-based cold-resistant composition with significant cold-resistant efficacy, environmental friendliness, high stability, and broad applicability, effectively overcoming many shortcomings of existing technologies.

[0087] The technical features of the embodiments described above 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 the combination of these technical features does not contradict each other, it should be considered within the scope of this specification. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A plant cold tolerance composition, characterized in that, The product comprises a natural extract of willow bark, a silicon source, a molybdenum source, a selenium source, and water. The natural extract of willow bark is used in an amount of 15-35 parts by weight of dry matter, and the content of salicin in the natural extract of willow bark is not less than 60%. The silicon source is used in an amount of 1-5 parts by weight of SiO2. The molybdenum source is used in an amount of 0.01-0.05 parts by weight of Mo. The selenium source is used in an amount of 0.01-0.05 parts by weight of Se. The remainder is water.

2. The plant cold tolerance composition of claim 1, wherein The natural extract of willow bark was prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder is mixed with deionized water at 50-60℃ at a material-to-liquid ratio of 1:12 to 1:15, and the mixture is stirred and extracted at a constant speed for 25-40 minutes to obtain a mixture. The material-to-liquid ratio is measured in g / mL. The mixture was placed in an ultrasonic device and ultrasonically treated for 20-30 min at a frequency of 20-100 kHz and a power of 100-150 W using pulse mode and ice bath cooling. The ultrasonically treated mixture is then filtered. Centrifuge the filtered mixture, collect the supernatant, and finally concentrate it under low temperature and reduced pressure to 1 / 5 to 2 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

3. The plant cold hardening composition of claim 1, wherein The amount of the natural willow bark extract used is 15-25 parts by weight of dry matter, and the ratio of the amount of silicon source, molybdenum source and selenium source is 100:(0.5-2):(0.5-2).

4. The plant cold hardening composition of claim 1, wherein The silicon source is selected from one or more of potassium silicate, sodium silicate, and organosilicon sol, wherein the particle size of the organosilicon sol is 10-50 nm; the molybdenum source is selected from one or more of sodium molybdate and ammonium molybdate; and the selenium source is selected from one or more of sodium selenite and sodium selenate.

5. A method for the preparation of a plant cold resistance composition according to any one of claims 1 to 4, characterized in that, include: (1) Preparation of natural extracts from willow bark; (2) The natural extract of willow bark, silicon source, molybdenum source, selenium source and water are mixed in proportion; The willow bark natural extract is used in an amount of 15-25 parts by weight of dry matter, the silicon source is used in an amount of 1-5 parts by weight of SiO2, the molybdenum source is used in an amount of 0.01-0.05 parts by weight of Mo, the selenium source is used in an amount of 0.01-0.05 parts by weight of Se, and the balance is water.

6. The method of claim 5, wherein the plant cold tolerance composition is prepared by mixing the plant cold tolerance composition with a carrier. The natural extract of willow bark was prepared by the following method: The dried willow bark is crushed to obtain willow bark powder; Willow bark powder is mixed with deionized water at 50-60℃ at a material-to-liquid ratio of 1:12 to 1:15, and the mixture is stirred and extracted at a constant speed for 25-40 minutes to obtain a mixture. The material-to-liquid ratio is measured in g / mL. The mixture was placed in an ultrasonic device and ultrasonically treated for 20-30 min at a frequency of 20-100 kHz and a power of 100-150 W using pulse mode and ice bath cooling. The ultrasonically treated mixture is then filtered. Centrifuge the filtered mixture, collect the supernatant, and finally concentrate it under low temperature and reduced pressure to 1 / 5 to 2 / 5 of the original volume to obtain a concentrated natural extract of willow bark.

7. The method of claim 6, wherein the plant cold hardening composition is prepared by, The pulse mode is working for 2-5 seconds and pausing for 1-2 seconds; the temperature of the ice bath cooling is 4-10 DEG C; The mixture after ultrasonic treatment is filtered through a 100-200 mesh sieve; The filtered mixture is centrifuged at 8000-10000 r / min for 15-30 min, the supernatant is taken, and finally the supernatant is concentrated to 1 / 5 of the original volume at 50-55 DEG C under reduced pressure to obtain a concentrated solution of willow bark natural extract.

8. The method for preparing the plant-based cold-resistant composition according to claim 6, characterized in that, The silicon source is selected from one or more of potassium silicate, sodium silicate and organic silicon sol, and the particle size of the organic silicon sol is 10-50 nm; The organic silicon sol is prepared by the following method: The industrial water glass is passed through a strong acid cation exchange resin to remove sodium ions and other impurities, and an active silicic acid solution is obtained; Under the assistance of ultrasonic, the active silicic acid solution is used as a silicon source, dilute ammonia is used as an alkali source, and a polymerization reaction is carried out at 60-70 DEG C and under uniform stirring, the pH value of the reaction system is controlled to be between 9.0-10.5, and a monodisperse silica sol primary product is formed; The silica sol primary product is subjected to cyclic concentration by using an ultrafiltration membrane, and a chitosan quaternary ammonium salt solution is added dropwise as a stabilizer during the process to obtain a nano-silica sol.

9. Use of a plant cold resistance composition in the cultivation of a crop plant, characterized in that, The plant cold resistance composition of any one of claims 1-4 is sprayed on the leaf surface of the crops 3-7 days before the arrival of low temperature cold wave.

10. Use according to claim 9, wherein the compound is ###0002### The plant cold resistance composition is diluted by 100-200 times, and is uniformly applied to the leaf surface of the crops by manual spraying 3-7 days before the arrival of low temperature cold wave; or the plant cold resistance composition is diluted by 10-20 times, and is uniformly applied to the leaf surface of the crops by unmanned aerial vehicle spraying 3-7 days before the arrival of low temperature cold wave.

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