Special fertilizer for oilseed rape and application of special fertilizer to prevention and treatment of sclerotinia rot of oilseed rape

Abstract

The invention relates to the technical field of agricultural science, and discloses a special fertilizer for oilseed rape and application of the special fertilizer to prevention and treatment of sclerotinia rot of oilseed rape, and the special fertilizer comprises the following components in percentage by mass: a selenium source which is sodium selenite with the content of 0.05%-0.1% (in terms of selenium element); the microbial agent is bacillus subtilis, the content is 5-10%, and the viable count is greater than or equal to 10 < 9 > CFU / g; the nutrient elements comprise the following components in percentage by weight: 20%-30% of urea, 15%-20% of diammonium phosphate and 10%-15% of potassium sulfate; the slow-release carrier is polylactic acid microspheres, and the content of the polylactic acid microspheres is 10-15%; and the auxiliary material comprises 5-10% of humic acid, 3-5% of a binder and less than or equal to 5% of water. The sodium selenite is combined with the bacillus subtilis, so that additional application of a bactericide is not needed, and chemical residues and environmental pollution are avoided.

Description

Technical Field

[0001] The invention relates to the field of agricultural science and technology, in particular to a special fertilizer for rapeseed and application thereof in preventing and controlling sclerotinia rot of rapeseed. Background Art

[0002] As an important oil crop, rapeseed (Brassicanapus) is widely planted around the world, and its yield and quality directly affect the agricultural economy. However, rapeseed sclerotinia (caused by Sclerotiniasclerotiorum) is one of the main diseases that restrict its production, especially under conditions of suitable humidity and temperature, which is prone to break out, resulting in bud shedding, stem rot and grain yield reduction. At present, the existing technologies for preventing and controlling rapeseed sclerotinia mainly include the application of chemical fungicides and agricultural tillage measures. Chemical fungicides such as carbendazim and prochloraz are usually sprayed during the flowering period of rapeseed to reduce the incidence rate by inhibiting the growth of pathogens; while tillage measures such as crop rotation, deep plowing of soil and adjustment of planting density indirectly control the disease by reducing the inoculation source of pathogens and improving the field environment. In addition, the application of traditional nitrogen, phosphorus and potassium fertilizers (such as urea, diammonium phosphate, potassium sulfate) is widely used to meet the growth needs of rapeseed to improve the overall health of the plant. These methods have alleviated the harm of sclerotinia to a certain extent and have become a routine practice in rapeseed cultivation.

[0003] However, the existing technology has significant drawbacks in the prevention and control of rapeseed sclerotinia, especially the over-reliance on chemical fungicides has brought multiple problems. First, the frequent use of fungicides leads to drug resistance in pathogens. For example, studies have shown that the use effect of carbendazim in some areas has decreased by 20%-30%, and the prevention and control efficiency has weakened year by year. Secondly, the residues of chemical fungicides in the soil and plants increase the risk of environmental pollution. For example, the half-life of carbendazim in the soil can reach several months, and after accumulation, it poses a potential threat to soil microbial communities and water ecology. In addition, the application of fungicides requires precise control of the timing of disease occurrence, and the operation is complicated and the cost is high (such as the cost of fungicides per hectare is about 100-200 yuan), which challenges the technical level and economic affordability of farmers. Although traditional fertilizers can promote growth, they lack direct disease resistance and cannot replace the role of fungicides in the prevention and control of sclerotinia. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a special fertilizer for rapeseed and its application in preventing and controlling rapeseed sclerotinia disease, which solves the problem that the residues of chemical fungicides in the soil and plants increase the risk of environmental pollution.

[0005] To achieve the above purpose, the present invention is implemented by the following technical scheme: a special fertilizer for rapeseed, comprising the following components in percentage by mass:

[0006] The selenium source is sodium selenite, with a content of 0.05%-0.1%, calculated as selenium element;

[0007] The microbial agent is Bacillus subtilis, with a content of 5%-10% and a viable count of greater than or equal to 10 9 CFU / g;

[0008] The nutrients include urea, which is 20%-30%, diammonium phosphate, which is 15%-20%, and potassium sulfate, which is 10%-15%;

[0009] The sustained-release carrier is polylactic acid microspheres with a content of 10%-15% and a particle size of 50-100 μm;

[0010] The auxiliary materials include humic acid with a content of 5%-10%, a binder with a content of 3%-5%, and a moisture content less than or equal to 5%.

[0011] Preferably, the Bacillus subtilis is strain ATCC6633.

[0012] Preferably, the content of sodium selenite is 0.07%-0.09%, providing a soil selenium concentration of 0.1-0.5 mg / kg.

[0013] Preferably, the sustained-release carrier polylactic acid microspheres are prepared by coating sodium selenite with high-speed stirring at a speed of 450-550 rpm and a temperature of 35-45°C.

[0014] Preferably, the binder is starch, and the content is 3.5%-4.5%.

[0015] Preferably, a method for preparing a special fertilizer for rapeseed comprises the following steps:

[0016] S1. Ferment Bacillus subtilis in liquid culture medium until the number of viable bacteria is greater than or equal to 10 9 CFU / g, the bacteria were collected by centrifugation and mixed with humic acid to make bacterial agent granules;

[0017] S2, dissolving sodium selenite in water, coating with polylactic acid microspheres under high-speed stirring, and forming sustained-release selenium particles after drying;

[0018] S3, mixing urea, diammonium phosphate and potassium sulfate in proportion, and adding a binder to prepare base fertilizer granules;

[0019] S4. Mix the bacterial agent granules, slow-release selenium granules and base fertilizer granules in a granulator, control the particle size to be 2-4 mm, and dry until the moisture content is less than or equal to 5% to obtain the finished product.

[0020] Preferably, the liquid culture medium in step S1 is LB culture medium, the fermentation temperature is 35-39° C., and the fermentation time is 45-50 hours.

[0021] Preferably, the high-speed stirring conditions in step S2 are stirring speed 450-550 rpm, temperature 35-45° C., and coating time 25-35 minutes.

[0022] Preferably, the use of a special fertilizer for rapeseed in preventing and controlling rapeseed sclerotinia disease comprises the following steps:

[0023] Before rapeseed is sown or in the seedling stage, the rapeseed special fertilizer is applied as a base fertilizer at an application rate of 150-200 kg per hectare, and mixed evenly into the soil in combination with tillage;

[0024] Used to control rapeseed sclerotinia and increase yield.

[0025] Preferably, the method further comprises spraying a selenium solution on the leaves of rapeseed during its flowering period, wherein the concentration of the selenium solution is 8-12 mg / L and the spraying amount is 200-300 L per hectare.

[0026] The present invention provides a special fertilizer for rapeseed and its application in preventing and controlling sclerotinia sclerotiorum of rapeseed. It has the following beneficial effects:

[0027] 1. The present invention is to prepare sodium selenite (0.05%-0.1%) and Bacillus subtilis (5%-10%, viable bacteria count ≥ 10 9 CFU / g), and utilize the dual mechanism of selenium enhancing the plant antioxidant system (such as increasing the activity of superoxide dismutase by 20%-30%) and microorganisms secreting antibacterial substances (such as lipopeptides) to inhibit Sclerotinia sclerotiorum, thereby significantly reducing the incidence of sclerotinia disease (such as from 30% to 5%, a reduction of 83%) in Example 2; unlike the prior art that relies on chemical fungicides (such as carbendazim), this solution does not require additional application of fungicides, thereby avoiding chemical residues and environmental pollution.

[0028] 2. The present invention uses polylactic acid microspheres (10%-15%, particle size 50-100 μm) as slow-release carriers to coat sodium selenite and some nutrients. This solution allows selenium and nutrients to be gradually released during the rapeseed growth period (about 120 days) (such as a daily release rate of 0.001-0.002 mg / g microspheres), increasing the selenium utilization rate from 30%-40% of traditional quick-release fertilizers to 60%-70%, and increasing the nitrogen, phosphorus and potassium utilization rates by 15%, 20% and 18%, respectively; in the prior art, most fertilizers are quick-release, easy to lose and unable to provide continuous disease protection, while the slow-release technology of the present solution not only prolongs the fertilizer effect, but also accurately supplies active ingredients during the high incidence period of sclerotinia disease (such as the flowering period).

[0029] 3. The present invention promotes rapeseed root development, photosynthesis and grain formation by balancing nutrient supply (20%-30% urea, 15%-20% diammonium phosphate, 10%-15% potassium sulfate) combined with the synergistic effect of humic acid (5%-10%) and selenium, and the yield is significantly increased (such as from 2200kg / ha to 2600kg / ha in Example 2, an increase of 18.2%), and the oil content of the grain is increased by 1.5%-3%. Compared with the prior art that only increases yield through NPK fertilizer (such as 9.5%), this solution combines disease resistance with nutritional optimization, and additionally improves the quality of rapeseed (such as an increase of 10%-15% in the number of siliques).

[0030] 4. The present invention improves soil structure (such as increasing organic matter content by about 5%-10%) by adding humic acid (5%-10%) and Bacillus subtilis, and improves soil structure by microbial colonization (rhizosphere bacteria density reaches 10 7 -10 8 CFU / g soil) enhances the disease suppression ability of the soil and inhibits the survival of pathogens; compared with the simple application of inorganic fertilizers in the prior art, this solution optimizes the soil microecology through the synergistic effect of organic and microorganisms, and reduces the inoculation source of sclerotinia disease (such as the survival rate of sclerotia is reduced by about 30%).

[0031] 5. The fertilizer application rate (150-200kg / ha) of the present invention can be adjusted according to soil fertility and disease severity, and can be combined with foliar spraying of selenium solution (8-12mg / L, 200-300L / ha) during the flowering period, which is suitable for different climates and soil conditions (such as the Yangtze River Basin and the Huanghuai Plain). In the prior art, the use of fertilizers and fungicides is relatively fixed and lacks flexibility, while this solution optimizes the application effect (such as reducing the number of lesions by another 30%) through the combination of base fertilizer and foliar spraying. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of a method for preparing a special fertilizer for rapeseed. DETAILED DESCRIPTION

[0033] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] Please see attached Figure 1 The embodiment of the present invention provides a rapeseed fertilizer, comprising the following components in percentage by mass:

[0035] The selenium source is sodium selenite, with a content of 0.05%-0.1%, calculated as selenium element;

[0036] The microbial agent is Bacillus subtilis, with a content of 5%-10% and a viable count of greater than or equal to 10 9 CFU / g;

[0037] The nutrients include urea, which is 20%-30%, diammonium phosphate, which is 15%-20%, and potassium sulfate, which is 10%-15%;

[0038] The sustained-release carrier is polylactic acid microspheres with a content of 10%-15% and a particle size of 50-100 μm;

[0039] The auxiliary materials include humic acid with a content of 5%-10%, a binder with a content of 3%-5%, and a moisture content less than or equal to 5%.

[0040] Specifically, the rapeseed-specific fertilizer is designed to achieve effective prevention and control of rapeseed sclerotinia by integrating a variety of functional components, while meeting the nutritional needs of rapeseed growth. Sodium selenite, as a selenium source, can enhance the antioxidant capacity by increasing the selenium content in plants, thereby inhibiting the infection of the sclerotinia pathogen Sclerotinias clerotiorum. Its content range of 0.05%-0.1% is based on the optimization result of the soil selenium background value and the plant absorption efficiency, ensuring that it can play an anti-disease role without exceeding the safety limit. Bacillus subtilis, as a microbial agent, can secrete antibacterial substances such as lipopeptides and proteases to directly inhibit the growth of pathogens. At the same time, it changes the soil microbial community structure through competition and reduces the survival space of pathogens. Its content is 5%-10% and the number of live bacteria is greater than or equal to 10 9 The design of CFU / g can ensure biological activity after field application. The nutrient elements urea, diammonium phosphate and potassium sulfate provide three main nutrients: nitrogen, phosphorus and potassium respectively. Among them, urea content of 20%-30% can promote rapeseed leaf growth and photosynthesis, diammonium phosphate content of 15%-20% can enhance root development and flower bud differentiation, and potassium sulfate content of 10%-15% can improve plant stress resistance and grain quality. These proportions have been optimized through field tests to ensure nutritional balance. Polylactic acid microspheres are used as slow-release carriers. Their particle size of 50-100μm can effectively encapsulate selenium sources and some nutrients, and release active ingredients through slow degradation, extending the fertilizer effect to about 120 days during the entire growth period of rapeseed, avoiding nutrient loss and environmental pollution caused by excessive application. The humic acid content of 5%-10% not only improves soil structure and promotes the absorption of nutrients by roots, but also enhances the survival rate and activity of microbial agents; the binder content of 3%-5% ensures the stability of the particles after forming, avoiding breakage during transportation and application; the moisture content is less than or equal to 5% to ensure the stability of the fertilizer during storage, preventing premature degradation of microorganisms or nutrient loss. The comprehensive design of this fertilizer enables it to significantly increase yield while preventing and controlling rapeseed sclerotinia, and is suitable for rapeseed cultivation in different soil types and climatic conditions.

[0041] The Bacillus subtilis was strain ATCC6633.

[0042] Specifically, the strain ATCC6633 of Bacillus subtilis was selected based on its excellent performance in the prevention and control of various agricultural diseases. After laboratory screening and field verification, the strain can efficiently produce antibacterial substances, such as surfactin and iturin, and has a significant inhibitory effect on Sclerotiniasclerotiorum, and its inhibition zone diameter can reach 15-20mm. In addition, the ATCC6633 strain shows good adaptability under different soil pH values ​​(5.5-7.5) and temperature ranges (15-35°C), and can stably function under the diverse environmental conditions of the main rapeseed producing areas. This strain was also selected because of its strong spore-forming ability. It can withstand adverse conditions such as high temperature and dryness during fertilizer production, storage and application, ensuring that the number of live bacteria is maintained at 10 9 CFU / g or more, thus ensuring rapid soil colonization and biological control after field application. Compared with other Bacillus subtilis strains, ATCC6633 has a stronger colonization ability in the rhizosphere of rapeseed, and the rhizosphere bacterial density can reach 10 7 -10 8 CFU / g soil, further enhancing the protection against Sclerotinia sclerotiorum.

[0043] The content of sodium selenite is 0.07%-0.09%, providing soil selenium concentration of 0.1-0.5 mg / kg.

[0044] Specifically, the sodium selenite content is set at 0.07%-0.09% based on the absorption characteristics of rapeseed to selenium and the optimal range of the control effect of sclerotinia. Through field experiments, it is found that when the soil selenium concentration reaches 0.1-0.5mg / kg, the selenium content in rapeseed leaves can be increased to 0.15-0.25mg / kg. This concentration range can significantly increase the activity of superoxide dismutase and peroxidase in plants, increasing by 20%-30% and 15%-25% respectively, thereby enhancing resistance to pathogen infection. In addition, this content range can also effectively reduce the diameter of sclerotinia lesions. Experiments show that the diameter of lesions is reduced from 5-8cm in the control group to 2-4cm, and the incidence rate is reduced by about 40%. This content design of sodium selenite also takes into account environmental safety, avoids excessive accumulation of soil selenium (the national standard is less than 3mg / kg), and controls the release rate through a slow-release carrier, so that selenium is continuously supplied during the critical stage from the seedling stage to the flowering stage of rapeseed, further optimizing the disease resistance effect.

[0045] The sustained-release carrier polylactic acid microspheres are prepared by coating sodium selenite with high-speed stirring at a speed of 450-550 rpm and a temperature of 35-45°C.

[0046] Specifically, the sustained-release carrier polylactic acid microspheres are made by coating sodium selenite with high-speed stirring. The process parameters of stirring speed of 450-550rpm and temperature of 35-45℃ have been optimized through multiple experiments, which can ensure that sodium selenite is evenly attached to the surface of the microspheres and embedded in their microporous structure to form a stable sustained-release system. The biodegradable characteristics of polylactic acid microspheres match their decomposition rate in the soil with the growth period of rapeseed, with a decomposition cycle of about 90-120 days. They can continuously release selenium during the flowering period of rapeseed (the peak period of sclerotinia disease), with a release rate of about 0.001-0.002mg / g microspheres per day, ensuring the disease resistance needs of plants at critical stages. The stirring speed range of 450-550rpm can avoid uneven coating caused by too low speed or microsphere breakage caused by too high speed, while the temperature of 35-45℃ ensures that the polylactic acid microspheres maintain physical stability during processing and avoid high-temperature degradation. Compared with traditional quick-release fertilizers, this slow-release design increases the utilization rate of selenium from 30%-40% to 60%-70%, significantly reducing nutrient waste.

[0047] The binder is starch, and the content is 3.5%-4.5%.

[0048] Specifically, starch is selected as the binder, and the content is set at 3.5%-4.5% because starch has good biodegradability and bonding properties, and can firmly bind the various components of the fertilizer into particles with a particle size of 2-4mm, ensuring that they are evenly distributed in the soil when applied. When the starch content is lower than 3.5%, the particles are easy to break, affecting the transportation and application effects; when it is higher than 4.5%, it may increase production costs and reduce the air permeability of the fertilizer, affecting the activity of microbial agents. After experimental verification, the starch content of 3.5%-4.5% makes the compressive strength of the particles reach 10-15N, which can withstand the pressure of conventional mechanized fertilization equipment. At the same time, it slowly decomposes after encountering water in the soil, and does not affect the release of nutrients and microorganisms. In addition, as a natural substance, starch will not introduce chemical residues, and synergistically with humic acid can also provide an additional carbon source for Bacillus subtilis, promoting its proliferation in the soil.

[0049] A method for preparing a special fertilizer for rapeseed comprises the following steps:

[0050] S1. Ferment Bacillus subtilis in liquid culture medium until the number of viable bacteria is greater than or equal to 10 9 CFU / g, the bacteria were collected by centrifugation and mixed with humic acid to make bacterial agent granules;

[0051] S2, dissolving sodium selenite in water, coating with polylactic acid microspheres under high-speed stirring, and forming sustained-release selenium particles after drying;

[0052] S3, mixing urea, diammonium phosphate and potassium sulfate in proportion, and adding a binder to prepare base fertilizer granules;

[0053] S4. Mix the bacterial agent granules, slow-release selenium granules and base fertilizer granules in a granulator, control the particle size to be 2-4 mm, and dry until the moisture content is less than or equal to 5% to obtain the finished product.

[0054] Specifically, the preparation method ensures the activity of each component and the realization of the overall function of the fertilizer through step-by-step processing and composite granulation process. In step S1, Bacillus subtilis is fermented to 10 9 CFU / g and then mixed with humic acid, which not only protects the survival of the bacteria, but also enhances its colonization ability in the soil. Humic acid can also absorb water and nutrients to provide a suitable microenvironment for the strain. In step S2, sodium selenite is coated on polylactic acid microspheres by high-speed stirring, and the drying process adopts 40-50℃ low-temperature drying to avoid volatilization of selenium or destruction of the microsphere structure, forming stable slow-release particles with a coating rate of 85%-90%. In step S3, the mixing ratio of urea, diammonium phosphate and potassium sulfate is accurately calculated to ensure that the ratio of nitrogen, phosphorus and potassium is about 2:1:1, which meets the growth requirements of rapeseed, and the base fertilizer particles formed after adding the binder have good physical strength. The granulation process of step S4 adopts a drum granulator, and the speed is controlled at 30-40rpm during the mixing process to avoid excessive or uneven particles. The drying temperature is controlled at 50-60℃ to ensure that the moisture content is less than or equal to 5%. The finished particles have high hardness and storage resistance, and can maintain stability under different climatic conditions.

[0055] In step S1, the liquid culture medium is LB culture medium, the fermentation temperature is 35-39° C., and the fermentation time is 45-50 hours.

[0056] Specifically, LB medium is selected in step S1 because it is rich in peptone and yeast extract, which can provide sufficient carbon and nitrogen sources for Bacillus subtilis, promote rapid growth and spore formation of the strain, and the fermentation temperature is 35-39°C to avoid the inhibition of high temperature on the activity of the strain, while ensuring the fermentation efficiency. The fermentation time is 45-50 hours so that the number of viable bacteria can stably reach 10 9 CFU / g or more. The pH value of LB medium is controlled at 6.8-7.2 to ensure that the strain is in the best growth state. After the fermentation is completed, the centrifugal speed is 8000-10000rpm. The collected bacteria are of high purity. The diameter of the particles formed after mixing with humic acid is about 0.5-1mm, which is convenient for the uniformity of the subsequent granulation process.

[0057] The conditions for high-speed stirring in step S2 are stirring speed 450-550 rpm, temperature 35-45° C., and coating time 25-35 minutes.

[0058] Specifically, in step S2, the high-speed stirring conditions are 450-550rpm, the temperature is 35-45°C, and the coating time is 25-35 minutes, which can form uniform slow-release selenium particles. The stirring speed range ensures that the sodium selenite solution is fully in contact with the polylactic acid microspheres, and the temperature range avoids the softening of polylactic acid or the decomposition of selenium. The coating time is 25-35 minutes so that the coating layer thickness reaches 10-15μm to ensure the slow-release effect. The drying process adopts hot air drying, with a wind speed of 2-3m / s, a temperature of 40-50°C, and a drying time of 2-3 hours to ensure that the moisture content of the particles is less than 5%. The selenium release cycle of the finished slow-release selenium particles can reach 90-120 days, which is highly matched with the growth period of rapeseed.

[0059] Application of a special fertilizer for rapeseed in preventing and treating sclerotinia sclerotiorum of rapeseed comprises the following steps:

[0060] Before rapeseed is sown or in the seedling stage, apply rapeseed fertilizer as base fertilizer at a rate of 150-200kg per hectare, and mix it evenly into the soil by tilling.

[0061] Used to control rapeseed sclerotinia and increase yield.

[0062] Specifically, this application method is designed according to the occurrence law of sclerotinia rot of rapeseed. Application before sowing or in the seedling stage can establish an early disease-resistant barrier for rapeseed. The application amount of 150-200kg per hectare can be flexibly adjusted according to soil fertility and the historical severity of sclerotinia rot. 150kg / ha can be used in mildly affected areas, and it can be increased to 200kg / ha in severely affected areas. Combined with tillage, the soil is evenly mixed to a depth of 10-15cm to ensure that the fertilizer is in full contact with the root system. The slow-release component begins to release selenium and nutrients when the soil moisture is greater than 50%, and the microbial agent quickly colonizes the rhizosphere within 1-2 weeks after application to form a biological protective layer. Field trials have shown that this method can reduce the incidence of sclerotinia rot from 20%-30% to 5%-10%, while increasing the number of rapeseed siliques by 10%-15%, and the plumpness of the grains by about 20%. It is suitable for rapeseed major producing areas such as the Yangtze River Basin and the Huanghuaihai Plain.

[0063] It also includes spraying selenium solution on the leaves during the flowering period of rapeseed, with a concentration of 8-12 mg / L and a spraying amount of 200-300L per hectare.

[0064] Specifically, the concentration of selenium solution sprayed on the leaves during the flowering period is 8-12 mg / L, which can quickly supplement the selenium content of the plant during the high incidence stage of sclerotinia disease and enhance the antioxidant capacity of the leaves. The spraying amount of 200-300L / ha is adjusted according to the rapeseed planting density. When the density is high (such as 400,000 plants per hectare), 300L / ha is used to ensure uniform leaf coverage. The spraying time is selected in the early morning or evening to avoid high temperature evaporation, and avoid rainfall within 24 hours after spraying to ensure the absorption effect. Experimental data show that foliar spraying can further reduce the number of lesions by about 30%, and synergize with base fertilizer to increase rapeseed yield by 8%-12%, while increasing the oil content of the grain by about 2%-3%, significantly improving the quality of rapeseed.

[0065] The following is an introduction in conjunction with specific embodiments:

[0066] Example 1: Minimum content formulation

[0067] Formula components (mass percentage):

[0068] Selenium source: sodium selenite 0.05%, calculated as selenium element;

[0069] Microbial agent: Bacillus subtilis (strain ATCC6633) 5%, viable count 10 9 CFU / g;

[0070] Nutrient elements: urea 20%, diammonium phosphate 15%, potassium sulfate 10%;

[0071] Sustained release carrier: polylactic acid microspheres 10%, particle size 50 μm;

[0072] Auxiliary materials: humic acid 5%, binder (starch) 3.5%, water 4.5%.

[0073] Preparation method:

[0074] S1: Ferment Bacillus subtilis in LB medium at 35°C for 45 hours until the viable count reaches 10 9 CFU / g, the bacteria were collected by centrifugation at a speed of 8000rpm and mixed with humic acid to form bacterial agent particles with a diameter of 0.5mm.

[0075] S2: Sodium selenite was dissolved in water, and stirred and coated with polylactic acid microspheres at a speed of 450 rpm, a temperature of 35°C, a time of 25 minutes, and hot air dried at 40°C for 2 hours to form sustained-release selenium particles.

[0076] S3: Mix urea, diammonium phosphate and potassium sulfate, add starch to make base fertilizer granules with a granule hardness of 10N.

[0077] S4: Mix the bacterial agent granules, slow-release selenium granules and base fertilizer granules to form granules, with a rotation speed of 30 rpm, a particle size of 2 mm, and dry at 50°C to a moisture content of 4.5%.

[0078] Application method:

[0079] Apply as basal fertilizer before sowing rapeseed, 150kg per hectare, and tillage depth of 10cm.

[0080] Effect:

[0081] Test location: Jingzhou, Hubei, soil selenium content 0.05 mg / kg.

[0082] The incidence of sclerotinia disease dropped from 25% in the control group to 10%, a 60% reduction;

[0083] Rapeseed yield was 2100kg per hectare, 10.5% higher than the control group (1900kg);

[0084] The soil selenium concentration rose to 0.15 mg / kg, and the plant selenium content was 0.12 mg / kg.

[0085] illustrate:

[0086] This embodiment adopts the minimum content of each component, is suitable for areas with high soil fertility and mild occurrence of sclerotinia, has low cost, and is suitable for small-scale planting.

[0087] Example 2: Highest content formula

[0088] Formula components (mass percentage):

[0089] Selenium source: sodium selenite 0.1%, calculated as selenium element;

[0090] Microbial agent: Bacillus subtilis (strain ATCC6633) 10%, viable count 1.2×10 9 CFU / g;

[0091] Nutrient elements: urea 30%, diammonium phosphate 20%, potassium sulfate 15%;

[0092] Sustained release carrier: polylactic acid microspheres 15%, particle size 100 μm;

[0093] Auxiliary materials: humic acid 10%, binder (starch) 4.5%, water 5%.

[0094] Preparation method:

[0095] S1: Bacillus subtilis was fermented in LB medium at 39°C for 50 hours, and the number of viable cells reached 1.2×10 9 CFU / g, the bacteria were collected by centrifugation at a speed of 10000rpm and mixed with humic acid to form bacterial agent particles with a diameter of 1mm.

[0096] S2: Sodium selenite was dissolved in water, and stirred with polylactic acid microspheres for coating at a speed of 550 rpm, a temperature of 45°C, a time of 35 minutes, and hot air dried at 50°C for 3 hours to form sustained-release selenium particles.

[0097] S3: Mix urea, diammonium phosphate and potassium sulfate, add starch to make base fertilizer granules with a granule hardness of 15N.

[0098] S4: Mix the bacterial agent granules, slow-release selenium granules and base fertilizer granules to form granules, with a rotation speed of 40 rpm, a particle size of 4 mm, and dry at 60°C to a moisture content of 5%.

[0099] Application method:

[0100] During the rapeseed seedling stage, apply basal fertilizer at a rate of 200 kg per hectare, with a tillage depth of 15 cm; during the flowering stage, spray selenium solution on the leaves at a concentration of 12 mg / L, 300 L per hectare.

[0101] Effect:

[0102] Test location: Yangzhou, Jiangsu, soil selenium content 0.03 mg / kg.

[0103] The incidence of sclerotinia disease dropped from 30% in the control group to 5%, a decrease of 83%;

[0104] The rapeseed yield was 2,600 kg per hectare, an increase of 18.2% over the control group (2,200 kg);

[0105] The soil selenium concentration rose to 0.45 mg / kg, the plant selenium content was 0.25 mg / kg, and the seed oil content increased by 3%.

[0106] illustrate:

[0107] This embodiment adopts the highest content of each component, is suitable for areas with poor soil and severe occurrence of sclerotinia, has the most significant disease resistance and yield-increasing effects, and is suitable for high-yield planting areas.

[0108] Example 3: Intermediate content formulation

[0109] Formula components (mass percentage):

[0110] Selenium source: sodium selenite 0.08%, calculated as selenium element;

[0111] Microbial agent: Bacillus subtilis (strain ATCC6633) 7%, viable count 1.1×10 9 CFU / g;

[0112] Nutrient elements: urea 25%, diammonium phosphate 18%, potassium sulfate 12%;

[0113] Sustained release carrier: polylactic acid microspheres 12%, particle size 75 μm;

[0114] Auxiliary materials: humic acid 8%, binder (starch) 4%, water 4.8%.

[0115] Preparation method:

[0116] S1: Bacillus subtilis was fermented in LB medium at 37°C for 48 hours, and the number of viable cells reached 1.1×10 9 CFU / g, the bacteria were collected by centrifugation at a speed of 9000rpm and mixed with humic acid to form bacterial agent particles with a diameter of 0.8mm.

[0117] S2: Sodium selenite was dissolved in water, and stirred and coated with polylactic acid microspheres at a speed of 500 rpm, a temperature of 40°C, a time of 30 minutes, and hot air dried at 45°C for 2.5 hours to form sustained-release selenium particles.

[0118] S3: Mix urea, diammonium phosphate and potassium sulfate, add starch to make base fertilizer granules with a granule hardness of 12N.

[0119] S4: Mix the bacterial agent granules, slow-release selenium granules and base fertilizer granules to form granules, with a rotation speed of 35 rpm, a particle size of 3 mm, and dry at 55°C until the moisture content reaches 4.8%.

[0120] Application method:

[0121] Apply basal fertilizer before sowing rapeseed, 180kg per hectare, and tillage depth of 12cm; spray selenium solution on the leaves during the flowering period, with a concentration of 10mg / L, 250L per hectare.

[0122] Effect:

[0123] Test location: Hefei, Anhui, soil selenium content 0.04 mg / kg.

[0124] The incidence of sclerotinia disease decreased from 28% in the control group to 8%, a decrease of 71%;

[0125] The rapeseed yield was 2400 kg per hectare, an increase of 14.3% over the control group (2100 kg);

[0126] The soil selenium concentration rose to 0.3 mg / kg, the plant selenium content was 0.18 mg / kg, and the number of siliques increased by 12%.

[0127] illustrate:

[0128] This embodiment adopts an intermediate content formula, balances cost and effect, is suitable for medium fertility soil and areas with moderate occurrence of sclerotinia disease, and has a wide range of applications.

[0129] Table 1:

[0130]

[0131]

[0132]

[0133] Table Description:

[0134] Recipe ingredients:

[0135] Embodiment 1-3: contains selenium, microorganisms and a slow-release carrier, and has an additional anti-disease functional component compared with the prior art.

[0136] Existing technology: Only traditional NPK fertilizers and fungicides (such as carbendazim) are used, without selenium and microbial ingredients.

[0137] Application rate:

[0138] Example 1: The minimum application rate is 150 kg / ha, suitable for areas with mild diseases.

[0139] Example 2: Maximum application rate 200 kg / ha + foliar spraying, suitable for areas with severe diseases.

[0140] Existing technology: additional application of fungicides is required, which increases the complexity of the operation.

[0141] Effect of Sclerotinia control:

[0142] Example 2: The incidence rate was reduced by 83%, with the best effect, thanks to the synergistic effect of high-content selenium and microorganisms.

[0143] Example 1: 60% reduction, still better than the prior art 57%, showing that even the lowest formulation is effective.

[0144] Prior art: relies on fungicides, and the effect is limited by the timing of application, which is inferior to the present invention.

[0145] Increased production:

[0146] Example 2: 18.2% increase in yield, thanks to comprehensive nutrition and disease protection.

[0147] Example 1: The yield is increased by 10.5%, slightly higher than the 9.5% of the prior art, and the cost-effectiveness is outstanding.

[0148] Existing technology: Limited yield increase, mainly dependent on fungicide protection rather than nutrient optimization.

[0149] Selenium content in soil and plants:

[0150] Example 1-3: The selenium content in soil is increased to 0.15-0.45 mg / kg, and the selenium content in plants is 0.12-0.25 mg / kg, thereby enhancing disease resistance.

[0151] Existing technology: No selenium supplementation, no change in selenium content in soil and plants.

[0152] Increased oil content in seeds:

[0153] Example 2: Oil content increased by 3%, which is related to high selenium content.

[0154] Existing technology: no significant improvement, lack of functional components.

[0155] Environmental impact and cost:

[0156] Embodiment 1-3: No chemical fungicide, slow-release technology reduces nutrient loss, highly environmentally friendly; cost is comparable to or lower than existing technology.

[0157] Existing technology: Fungicide residues increase environmental risks and costs are higher due to additional agents.

[0158] Summary and Analysis

[0159] Example 1 (minimum content): suitable for low-cost, low-disease scenarios, and the prevention and control effect and yield increase are slightly better than the existing technology.

[0160] Example 2 (highest content): The comprehensive performance is the best, and the control effect and yield significantly exceed the existing technology, which is suitable for high-yield needs.

[0161] Example 3 (intermediate content): Balances cost and effect, and has the widest applicability.

[0162] Existing technology: relies on fungicides, has limited effects and poses environmental risks, and is generally inferior to the present invention.

[0163] Table characters and term explanation:

[0164] Header indicators

[0165] index

[0166] Refers to specific parameters or performance categories used in the table to compare different embodiments and prior art, such as formulation components, application rates, sclerotinia incidence, etc.

[0167] Formula ingredients (mass %)

[0168] Sodium selenite

[0169] Chemical formula: Na2SeO3. As a selenium source, it provides the trace element selenium required by plants. The content is expressed as a mass percentage (such as 0.05%), calculated as selenium element (i.e., the actual selenium content is calculated, not the total amount of the compound). Selenium enhances the antioxidant capacity of plants and inhibits sclerotinia disease.

[0170] Bacillus subtilis

[0171] A beneficial microorganism, scientific name Bacillus subtilis, the content is expressed as mass percentage (such as 5%), and the number of viable bacteria is measured in CFU / g (colony forming units per gram) (such as 10 9 CFU / g) indicates the number of viable bacteria per gram of fertilizer. It is used for biological control of the pathogen Sclerotiniasclerotiorum.

[0172] Urea

[0173] Chemical formula CO(NH2)2, nitrogen fertilizer, provides nitrogen required for plant growth, the content is expressed as mass percentage (such as 20%), and promotes rapeseed leaf growth and photosynthesis.

[0174] Diammonium phosphate

[0175] Chemical formula (NH4)2HPO4, a phosphorus and nitrogen fertilizer, provides phosphorus and part of nitrogen, the content is expressed as mass percentage (such as 15%), enhancing root development and flower bud differentiation.

[0176] Potassium sulfate

[0177] Chemical formula K2SO4, potash fertilizer, provides potassium element, the content is expressed as mass percentage (such as 10%), improves plant resistance and grain quality.

[0178] Polylactic acid microspheres

[0179] A biodegradable slow-release carrier, chemically named polylactic acid (PLA), with a content expressed in mass percentage (such as 10%) and a particle size expressed in micrometers (μm) (such as 50 μm), is used to encapsulate selenium and nutrients to extend the release period.

[0180] Humic acid

[0181] Organic matter, the content of which is expressed as a percentage by mass (e.g. 5%), improves soil structure, enhances microbial activity, and promotes nutrient absorption.

[0182] Binder (starch)

[0183] Natural starch, as a granule forming agent, has a content expressed as a mass percentage (eg 3.5%), to ensure the physical stability of the fertilizer granules.

[0184] Moisture

[0185] The water content in the fertilizer, expressed as a mass percentage (eg, 4.5%), is less than or equal to 5% to ensure storage stability.

[0186] Fungicides

[0187] Commonly used chemical fungicides in the prior art (such as carbendazim) are expressed in "recommended doses" (such as 1-2 kg per hectare) for the prevention and control of sclerotinia disease.

[0188] Application amount and auxiliary measures

[0189] Application rate (kg / ha)

[0190] The mass of fertilizer or fungicide applied per hectare is expressed in kilograms per hectare (kg / ha) (e.g. 150kg / ha), reflecting the actual amount used in the field.

[0191] Foliar spray

[0192] During the flowering period of rapeseed, additional selenium solution is sprayed, with the concentration expressed in milligrams per liter (mg / L) (such as 12 mg / L) and the total amount expressed in liters per hectare (L / ha) (such as 300 L / ha) to enhance the disease resistance effect.

[0193] Performance indicators

[0194] Sclerotinia disease incidence

[0195] The infection rate of Sclerotinia sclerotiorum is expressed as a percentage (such as "control 25% → 10%"), with the reduction rate in brackets (such as "reduction by 60%"). The calculation formula is: (control incidence rate - treatment incidence rate) / control incidence rate × 100%.

[0196] Yield (kg / ha)

[0197] Rapeseed yield is expressed in kilograms per hectare (such as "control 1900→2100"), with the percentage increase in brackets (such as "+10.5%"). The calculation formula is: (treatment yield-control yield) / control yield×100%.

[0198] Soil selenium content (mg / kg)

[0199] The concentration of selenium in the soil before and after fertilization, expressed in milligrams per kilogram (such as "initial 0.05→0.15"), reflects the cumulative effect of selenium.

[0200] Plant selenium content (mg / kg)

[0201] The concentration of selenium in rapeseed plants, expressed in milligrams per kilogram (e.g. 0.12 mg / kg), reflects the plant's absorption of selenium.

[0202] Increase in seed oil content (%)

[0203] The percentage increase in rapeseed oil content (e.g. +1.5%), relative to the control group, reflects improved quality.

[0204] Environmental impact

[0205] Qualitatively describe the impact of fertilization on the environment, such as "no chemical residue" means no fungicide pollution, and "slow release reduces loss" means high nutrient utilization rate and reduced environmental load.

[0206] Cost estimation (yuan / ha)

[0207] The estimated cost of applying fertilizer per hectare, expressed in RMB (e.g., "about 600-700"), is based on raw material prices, production process and application rate.

[0208] Examples of specific meanings of table characters

[0209] "0.05%" (sodium selenite in Example 1): means that the sodium selenite in the fertilizer accounts for 0.05% of the total mass, providing the minimum selenium content.

[0210] "10 9 CFU / g”(Bacillus subtilis): Each gram of fertilizer contains 1 billion viable bacterial units to ensure microbial activity.

[0211] "Control 25%→10% (reduction of 60%)" (Sclerotinia disease incidence in Example 1): The incidence of the control group was 25%, which dropped to 10% after application, and the reduction was (25-10) / 25×100%=60%.

[0212] "Control 1900→2100 (+10.5%)" (yield of Example 1): The yield of the control group was 1900 kg / ha, which increased to 2100 kg / ha after application, with an increase of (2100-1900) / 1900×100%=10.5%.

[0213] “Initial 0.05→0.15” (selenium content in soil in Example 1): the selenium content in soil was 0.05 mg / kg before fertilization and increased to 0.15 mg / kg after fertilization.

[0214] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A special fertilizer for rapeseed, characterized in that: The following components are included in mass percentage: The selenium source is sodium selenite, with a content of 0.05%-0.1%, calculated as selenium element; The microbial agent is Bacillus subtilis, with a content of 5%-10% and a viable count of greater than or equal to 10 9 CFU / g; The nutrients include urea, which is 20%-30%, diammonium phosphate, which is 15%-20%, and potassium sulfate, which is 10%-15%; The sustained-release carrier is polylactic acid microspheres with a content of 10%-15% and a particle size of 50-100 μm; The auxiliary materials include humic acid with a content of 5%-10%, a binder with a content of 3%-5%, and a moisture content less than or equal to 5%.

2. The rapeseed fertilizer according to claim 1, characterized in that: The Bacillus subtilis is strain ATCC6633.

3. The rapeseed fertilizer according to claim 1, characterized in that: The content of sodium selenite is 0.07%-0.09%, providing soil selenium concentration of 0.1-0.5 mg / kg.

4. The rapeseed fertilizer according to claim 1, characterized in that: The sustained-release carrier polylactic acid microspheres are prepared by coating sodium selenite with high-speed stirring at a stirring speed of 450-550 rpm and a temperature of 35-45°C.

5. The rapeseed fertilizer according to claim 1, characterized in that: The binder is starch, and the content is 3.5%-4.5%.

6. A method for preparing a special fertilizer for rapeseed, characterized in that: The rapeseed fertilizer according to any one of claims 1 to 5 comprises the following steps: S1. Ferment Bacillus subtilis in liquid culture medium until the number of viable bacteria is greater than or equal to 10 9 CFU / g, the bacteria were collected by centrifugation and mixed with humic acid to make bacterial agent granules; S2, dissolving sodium selenite in water, coating with polylactic acid microspheres under high-speed stirring, and forming sustained-release selenium particles after drying; S3, mixing urea, diammonium phosphate and potassium sulfate in proportion, and adding a binder to prepare base fertilizer granules; S4. Mix the bacterial agent granules, slow-release selenium granules and base fertilizer granules in a granulator, control the particle size to be 2-4 mm, and dry until the moisture content is less than or equal to 5% to obtain the finished product.

7. The method for preparing rapeseed fertilizer according to claim 6, characterized in that: The liquid culture medium in step S1 is LB culture medium, the fermentation temperature is 35-39° C., and the fermentation time is 45-50 hours.

8. The method for preparing rapeseed fertilizer according to claim 6, characterized in that: The conditions for high-speed stirring in step S2 are stirring speed 450-550 rpm, temperature 35-45° C., and coating time 25-35 minutes.

9. Application of a special fertilizer for rapeseed in preventing and treating sclerotinia sclerotiorum of rapeseed, characterized in that: The rapeseed fertilizer according to any one of claims 1 to 5 comprises the following steps: Before rapeseed is sown or in the seedling stage, the rapeseed special fertilizer is applied as a base fertilizer at an application rate of 150-200 kg per hectare, and mixed evenly into the soil in combination with tillage; Used to control rapeseed sclerotinia and increase yield.

10. The use of the rapeseed-specific fertilizer according to claim 9 for preventing and treating rapeseed sclerotinia rot, characterized in that: The method also includes spraying a selenium solution on the leaves of rapeseed during its flowering period, wherein the concentration of the selenium solution is 8-12 mg / L and the spraying amount is 200-300 L per hectare.

Images