Staphylococcus warneri fungicide for inhibiting pythium aphanidermatum as well as preparation method and application thereof

Abstract

The invention relates to the technical field of agricultural microbial agents, and particularly discloses a staphylococcus warneri microbial agent for inhibiting pythium aphanidermatum as well as a preparation method and application of the staphylococcus warneri microbial agent. The staphylococcus warneri bacterial agent is prepared by mixing staphylococcus warneri bacterial slurry and a sustained-release auxiliary material according to a mass ratio of 1: (1-3) and granulating, the staphylococcus warneri bacterial slurry comprises staphylococcus warneri bacterial liquid and a drying protective agent, the solid content of the staphylococcus warneri bacterial liquid is 60-80%, and the mass of the drying protective agent is 1-10% of the mass fraction of the staphylococcus warneri bacterial liquid; the slow-release auxiliary material is prepared by mixing a carrier auxiliary material, a slow-release auxiliary material and trace elements in a mass ratio of (6-8): (1.5-3): (0.5-1). The staphylococcus warneri bacterial agent has a remarkable inhibition effect on pythium aphanidermatum, can remarkably reduce the harm of pythium aphanidermatum to various crops, and can be used as an efficient and environment-friendly agricultural disease control means.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of agricultural microbial inoculants, and specifically discloses a Staphylococcus warneri inoculant for inhibiting Pythium aphanidermatum, a preparation method and application thereof. BACKGROUND

[0002] Pythium spp. is a kind of pathogenic fungi with wide host range and strong invasion ability, which is widely distributed in the world, in various habitats such as land, salt water or fresh water, cultivated or uncultivated soil, and in plants or animals. According to statistics, the diseases caused by Pythium spp. in different crops have caused billions of dollars of global food economic losses.

[0003] Pythium aphanidermatum is an important plant pathogenic fungus, and is one of the most invasive pathogenic fungi in the genus Pythium. Pythium aphanidermatum has a wide host range, mainly including common plants such as Cucurbitaceae, Solanaceae, Leguminosae and Gramineae, and causes serious harm to economic crops such as vegetables and fruits and important food crops. The disease symptoms caused by Pythium aphanidermatum mainly include the rotting and sudden collapse of various crops. In recent years, Pythium has been widely reported as an important pathogenic fungus that can cause many seedling diseases of crops such as sudden collapse, stand failure, root rot, stem rot and fruit rot. The seedling diseases caused by Pythium aphanidermatum mainly manifest in the waterlogged appearance of the plant embryo stem base or middle part, resulting in the collapse of cotyledons before wilting. Pythium aphanidermatum often occurs in melon, legume, pepper and eggplant and other fruit vegetables, especially in crops such as cucumber and tomato, and often causes the corruption and deterioration of fruit vegetables, causing great losses to agricultural production and food safety. Pythium aphanidermatum is a fungus with strong adaptability, so the tomato wilt caused by Pythium aphanidermatum does not only occur in high-temperature seasons, but also can occur seriously in environments with low temperature and high humidity. The disease cycle of Pythium aphanidermatum is that the oospores overwinter in the soil, the sporangia and zoospores produced on the diseased residues can be transmitted and infected by rainwater, or directly grow out of the germ tube to invade the host, and finally form oospores to overwinter in the diseased tissue. The occurrence of the disease caused by Pythium aphanidermatum tends to be more serious with the improvement of soil water and fertilizer conditions.

[0004] Biological control has attracted widespread attention due to its environmental friendliness and non-toxicity to non-target organisms. The microorganisms reported to have inhibitory effect on Pythium aphanidermatum include Bacillus subtilis, Trichoderma harzianum and Streptomyces microflavus, but there is no report on the inhibition of Staphylococcus warneri on Pythium aphanidermatum. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art, and provides a Staphylococcus warneri inoculant for inhibiting Pythium aphanidermatum, a preparation method and application thereof.

[0006] The application discloses a Staphylococcus warneri bacterial agent for inhibiting Pythium aphanidermatum. The Staphylococcus warneri bacterial agent for inhibiting Pythium aphanidermatum comprises: Staphylococcus warneri bacterial slurry and slow-release auxiliary materials which are mixed at a mass ratio of 1:1-3 to form granules; the Staphylococcus warneri bacterial slurry comprises Staphylococcus warneri bacterial liquid and a dry protective agent, the solid content of the Staphylococcus warneri bacterial liquid is 60-80%, and the mass fraction of the dry protective agent is 1-10% of the mass fraction of the Staphylococcus warneri bacterial liquid; the slow-release auxiliary materials comprise carrier auxiliary materials, slow-release auxiliary materials and trace elements which are mixed at a mass ratio of 6-8:1.5-3:0.5-1.

[0007] Preferably, the Staphylococcus warneri is from the CGMCC (China General Microbiological Culture Collection Center), and the strain preservation number is CGMCC1.2824.

[0008] Preferably, the carrier auxiliary materials comprise diatomite, attapulgite and bran which are mixed at a mass ratio of 1-3:1-3:1.

[0009] Preferably, the slow-release auxiliary materials comprise chitosan, humic acid and amino acid powder which are mixed at a mass ratio of 1-2:1-2:1.

[0010] Preferably, the trace elements comprise zinc sulfate, FeEDTA, manganese sulfate, cobalt chloride and sodium molybdate which are mixed at a mass ratio of 2-4:2-4:1-2:1-2:1-2.

[0011] Preferably, the dry protective agent comprises trehalose, lactose, glycerol and dimethyl sulfoxide which are mixed at a mass ratio of 1:1-2:1-2:2-4.

[0012] The application discloses a Staphylococcus warneri bacterial agent for inhibiting Pythium aphanidermatum. The application discloses a Staphylococcus warneri bacterial agent for inhibiting Pythium aphanidermatum. Step one, primary seed liquid culture: Staphylococcus warneri is inoculated into a seed liquid culture medium, and is cultured in a 25-35 DEG C incubator at a shaking speed of 150-200 rpm for 18-30 h to obtain a primary seed liquid; Step two, secondary seed liquid culture: the primary seed liquid is inoculated into a primary seed tank at an inoculation amount of 10-20%, and is cultured at a temperature of 25-35 DEG C, a rotating speed of 150-200 rpm, a pH of 6.5-7.2 and a dissolved oxygen of 20-50% for 18-30 h to obtain a secondary seed liquid; Step three, fermenter culture: inoculate 10-20% volume fraction of the secondary seed liquid and 1% volume fraction of Pythium aphanidermatum into the fermenter, and the culture conditions are temperature 25-35℃, rotation speed 150-200rpm, pH 6.5-7.2, and culture for 20-36h until Pythium aphanidermatum is not detected in the fermentation broth; Step four, treatment of bacterial liquid: centrifuge the fermentation broth, adjust the solid content of Staphylococcus warneri bacterial liquid to 60-80%, and add 1-10% mass fraction of dry protective agent to the adjusted Staphylococcus warneri bacterial liquid to obtain bacterial slurry; Step five, granulation and drying: mix the bacterial slurry with excipients to granulate, and vacuum dry the solid particles at a temperature of 30-50℃ for 10-20h to obtain a solid product.

[0013] Preferably, the seed liquid culture medium in step one is LB culture medium.

[0014] Preferably, the primary seed tank in step two and the fermenter in step three each comprises the following components: glucose 2-5g / L, corn syrup 2-5g / L, molasses 0.5-1g / L, (NH4)2SO40.3-0.8g / L, K2HPO40.1-0.5g / L, NaH2PO40.1-0.5g / L, MnSO4·H2O 0.01-0.05g / L, FeSO4·7H2O 0.01-0.05g / L, Na2MoO40.01-0.05g / L, MgSO4·7H2O 0.01-0.05g / L, and CoCl20.01-0.05g / L.

[0015] In a third aspect, the application discloses an application of Staphylococcus warneri bacterial agent for inhibiting Pythium aphanidermatum, which can be used as base application and follow-up application, and the application amount is 1-10kg / acre.

[0016] Compared with the prior art, the application has at least the following beneficial effects: The Staphylococcus warneri bacterial agent has a significant effect on inhibiting Pythium aphanidermatum, can significantly reduce the harm of Pythium aphanidermatum to various crops such as cucumber, pumpkin, tomato, pepper and eggplant, and can be used as an efficient and environmentally friendly agricultural disease control method. In addition, the bacterial agent can be slowly released in the soil by mixing the Staphylococcus warneri bacterial slurry and the slow-release excipient at a specific mass ratio, thereby prolonging the effective action time of the bacterial agent and improving the utilization rate and control effect of the bacterial agent. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned purposes, features and advantages of the application more apparent and easy to understand, the application will be further described in detail below with reference to the specific embodiments.

[0018] Example 1 The embodiment discloses a staphylococcus warneri agent for inhibiting pythium aphanidermatum, and a preparation method thereof. Step one, primary seed liquid culture: staphylococcus warneri is inoculated into a seed liquid culture medium, and is cultured in a 30 DEG C incubator for 24 h at a rotating speed of 180 rpm, so that a primary seed liquid is obtained; Step two, secondary seed liquid culture: the primary seed liquid is inoculated into a primary seed tank at a 15% inoculation amount, and is cultured for 24 h under the conditions of a temperature of 30 DEG C, a rotating speed of 180 rpm and a pH of 7.0 and a dissolved oxygen of 40%, so that a secondary seed liquid is obtained; Step three, fermenter culture: the secondary seed liquid with a volume fraction of 15% and pythium aphanidermatum with a volume fraction of 1% are inoculated into a fermenter, and are cultured for 30 h under the conditions of a temperature of 30 DEG C and a rotating speed of 180 rpm and a pH of 7.0, so that pythium aphanidermatum is not detected in the fermentation liquid; Step four, bacterial liquid treatment: the fermentation liquid obtained in step three is centrifuged, the solid content of the staphylococcus warneri bacterial liquid is adjusted to 60%, and 5% of a dry protection agent is added into the adjusted bacterial liquid, so that a bacterial slurry is obtained; Step five, granulation and drying: the bacterial slurry is mixed with auxiliary materials at a mass ratio of 1:1.5 for granulation, and the solid particles are vacuum dried at a temperature of 30 DEG C for 20 h, so that a solid product is obtained.

[0019] In step one, the staphylococcus warneri is purchased from the CGMCC (China General Microbiological Culture Collection Center), and the strain preservation number is CGMCC1.2824. In step one, the seed liquid culture medium is an LB culture medium.

[0020] The primary seed tank in step two and the fermenter in step three are both prepared from the following components: glucose 4 g / L, corn syrup 4 g / L, molasses 1 g / L, (NH4)2SO4 0.6 g / L, K2HPO4 0.2 g / L, NaH2PO4 0.3 g / L, MnSO4·H2O 0.04 g / L, FeSO4·7H2O 0.04 g / L, Na2MoO4 0.04 g / L, MgSO4·7H2O 0.04 g / L and CoCl2 0.04 g / L.

[0021] The pythium aphanidermatum added in step three is a pythium aphanidermatum zoospore suspension, and the preparation method of the pythium aphanidermatum zoospore suspension is as follows: (1) The preserved pythium aphanidermatum strain is activated and grown on a 10% V8 culture medium, and is cultured in a 25 DEG C constant-temperature incubator in the dark, and the culture time is generally 1-2 days; (2) The pythium aphanidermatum strain cultured for 1-2 days is cut into a mycelium block with a size of 10 mm*15 mm by using a scalpel; (3) 10-20 pieces of the above mycelium blocks are placed in 15 mL of sterilized tap water, and the mycelium surface of the mycelium blocks is replaced with water every 30 min; (4) After repeating the above steps for 3 times, 8 mL of sterilized water is added to just cover the mycelium surface; (5) The culture is placed in a 25°C constant temperature incubator for 20-24 h to induce the production of zoospores; (6) The zoospore suspension is adjusted to a concentration of about 1-5 x 10 6 / mL with sterile water, and the concentration of the present embodiment is 1 x 10 6 / mL.

[0022] In step four, the dry protective agent includes trehalose, lactose, glycerol, and dimethyl sulfoxide mixed in a mass ratio of 1:1.5:2:2.

[0023] In step five, the auxiliary materials include carrier auxiliary materials, slow-release auxiliary materials, and trace elements mixed in a mass ratio of 6:3:1. The carrier auxiliary materials include diatomite, attapulgite, and bran mixed in a mass ratio of 2:2:1. The slow-release auxiliary materials include chitosan, humic acid, and amino acid powder mixed in a mass ratio of 2:2:1. The trace elements include zinc sulfate, FeEDTA, manganese sulfate, cobalt chloride, and sodium molybdate mixed in a mass ratio of 2:2:1:1:1.

[0024] To verify the effective bacteria preservation effect of the solid granulation treatment of the present scheme, the viable bacteria count of the fermentation broth obtained in step three and the solid product obtained in step five is compared, and the comparison of the rate of miscellaneous bacteria during the preservation process is also made. The detection results are shown in Table 1 and Table 2.

[0025] Table 1. Comparison of viable bacteria count of fermentation broth and solid product during 0-24 months of preservation process

[0026] Table 2. Comparison of the rate of miscellaneous bacteria (%) of fermentation broth and solid product during 0-24 months of preservation process

[0027] From the comparison of the detection results in Table 1 and Table 2, it can be seen that after the treatment of the bacterial solution by adding dry protective agents and the granulation and drying treatment of mixing carrier auxiliary materials, slow-release auxiliary materials, and trace elements, the solid product still has a high level of viable bacteria count after 24 months of preservation, and the rate of miscellaneous bacteria can be maintained at a very low level.

[0028] To verify the contribution effect of the present scheme to the product quality of the microbial inoculant, the following Comparative Examples 1-3 are compared and verified.

[0029] Comparative Example 1 The difference between Example 1 and Comparative Example 1 is only that 1% of Pythium aphanidram was not added in the fermentation tank in Step 3, and the rest is the same as Example 1. The inhibition rate (%) of the solid product prepared in Comparative Example 1 on Pythium aphanidram was detected, and the detection method of the inhibition rate of Pythium aphanidram is as follows: A mycelium block with a diameter of about 5 mm was punched with a sterile punch and transferred to the center of a new PDA medium, and 0.01 g of the fungicide was applied at four equidistant points near the periphery of the culture. The culture was incubated at 25°C for 7 days. After the pathogenic fungus grew on the control plate to the entire surface of the medium, the antifungal activity was estimated by measuring the radial growth diameter of the fungus in the antagonistic experiment. .

[0030] The effect comparison of the inhibition rate (%) of the solid product on Pythium aphanidram is shown in Table 3.

[0031] Table 3. Comparison of the inhibition effect of the solid product prepared in Example 1 and Comparative Example 1 on Pythium aphanidram Inhibition rate (%) Example 1 83.1 Comparative Example 1 62.5 From the inhibition effect comparison in Table 3, the inhibition rate of Comparative Example 1 without adding Pythium aphanidram for fermentation is significantly lower than that of Example 1, which proves that adding Pythium aphanidram for fermentation during the fermentation process can improve the inhibition effect of Staphylococcus warneri on Pythium aphanidram. This is because adding Pythium aphanidram during the fermentation process can significantly improve the inhibition effect of Staphylococcus warneri on Pythium aphanidram through various ways such as activating the induced resistance mechanism of Staphylococcus warneri, establishing a competitive growth advantage, regulating metabolic products, and enhancing strain adaptability.

[0032] Comparative Example 2 The difference between Example 1 and Comparative Example 2 is only that trehalose, lactose, glycerol and dimethyl sulfoxide were used as single dry protection agents instead of the compound dry protection agent of Example 1 in Step 4 under the premise of maintaining the same amount of dry protection agent, and the rest is the same as Example 1. The microbial amount (cfu / g) of the solid product prepared was compared, and the detection results are shown in Table 4.

[0033] Table 4. Comparison of microbial amount (cfu / g) of solid product prepared by different dry protection agents

[0034] From the microbial amount detection results of Table 4, it can be seen that different types of dry protection agents have different degrees of influence on the activity of Staphylococcus warneri. Although trehalose, lactose, glycerol and dimethyl sulfoxide can also provide certain dry protection effect for the solid product when used as a single dry protection agent, the single dry protection agent has limitations. For example, although trehalose, lactose and glycerol have good moisturizing property and stability and can provide certain protection effect, the use of trehalose alone at a high concentration can cause excessive osmotic pressure on the surface of Staphylococcus warneri, affecting the activity of the bacterial cells. The use of lactose alone can cause moisture absorption during the drying process, resulting in clumping on the surface of the bacterial cells, affecting the dispersibility and activity of the bacterial cells. The use of glycerol alone can cause excessive stickiness, affecting the dispersibility of the bacterial cells, resulting in aggregation of the bacterial cells during the drying process and reducing the activity of the bacterial cells. Dimethyl sulfoxide has good permeability and protection effect, but its use alone can cause certain toxicity to Staphylococcus warneri due to its strong organic solvent properties, affecting the activity of the bacterial cells. Only the dry protection agent prepared by simultaneously using trehalose, lactose, glycerol and dimethyl sulfoxide in Example 1 can exert the synergistic effect of the components, thereby achieving the ideal microbial amount level and ensuring the effectiveness and stability of the solid product in subsequent applications.

[0035] Comparative Example 3 The difference between Example 1 and Comparative Example 3 is that in Step 5, chitosan, humic acid and amino acid powder are used as single sustained-release adjuvant instead of the compound sustained-release adjuvant of Example 1 under the premise of maintaining the same amount of sustained-release adjuvant, and the rest is the same as Example 1. The sustained-release effect of the solid product is compared, and the detection results are shown in Table 5.

[0036] Table 5. Comparison of sustained-release effect of solid products prepared by different sustained-release adjuvants

[0037] Note: Half-release period: time required for 50% release of the microbial agent.

[0038] 7d release rate: percentage of the number of viable bacteria released within 7d to the total number of bacteria loaded.

[0039] 30d release rate: percentage of the number of viable bacteria released within 30d to the total number of bacteria loaded.

[0040] From the comparison of the slow-release effect detection results in Table 5, it can be seen that different types of slow-release adjuvants have different effects on the slow-release effect of S. warneri solid products. Although chitosan, humic acid and amino acid powder can also play a certain slow-release role as a single slow-release adjuvant, the release speed is relatively fast and the half-release period is relatively short when chitosan, humic acid or amino acid powder is used alone, which cannot meet the long-term slow-release requirement. However, the slow-release adjuvant prepared by compounding chitosan, humic acid and amino acid powder can play a synergistic effect of each component: chitosan provides good biocompatibility and slow-release performance, humic acid provides adsorption, and amino acid powder provides biocompatibility and slow-release performance. This compounding method can fully meet the various needs of the bacterial body in the slow-release process, so as to better achieve the slow-release effect and ensure the persistence and effectiveness of the solid product in the soil.

[0041] Example 2 The present embodiment discloses an application of S. warneri bacterial agent for inhibiting Pythium aphanidermatum, which is specifically as follows. S. warneri is applied to the roots of various plants, and the dosage is 4 kg per mu. The control group is not applied with S. warneri. After 14 days, Pythium aphanidermatum is infected, and the disease index and control effect of the plants are calculated after 7 days of action. The control results are shown in Table 6. .

[0042] Plant judgment criteria: 0-plant remains green and healthy; 1-leaf sheath ring discoloration and lower leaf yellowing; 2-plant survival, but leaf complete yellowing or death; 3-entire plant death.

[0043] .

[0044] Table 6. Control effect of S. warneri bacterial agent on Pythium aphanidermatum

[0045] From the comparison of the control effect of Example 2, it can be seen that the S. warneri solid bacterial agent of the present scheme as a kind of biocontrol agent can significantly reduce the harm of Pythium aphanidermatum to cucumber, pumpkin, tomato, pepper, eggplant and other crops, improve the health level and disease resistance of crops, and provide an efficient and environmentally friendly solution for agricultural disease control.

[0046] The technical solutions provided by the present application are described in detail above, and the principles and implementation manners of the present application are described by applying specific examples. The above description of the examples is only used to help understand the method of the present application and its core idea. Meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed, and the above description should not be understood as a limitation on the present application.

Claims

1. A Staphylococcus warwick inoculant for inhibiting Pythium spp. in melons and fruits, characterized in that, include: Staphylococcus wartii mycelium slurry and slow-release excipients are mixed and granulated at a mass ratio of 1:1 to 3. The Staphylococcus wartii slurry comprises Staphylococcus wartii bacterial liquid and a desiccant, wherein the solid content of the Staphylococcus wartii bacterial liquid is 60-80%, and the mass of the desiccant is 1-10% of the mass fraction of the Staphylococcus wartii bacterial liquid; The sustained-release excipients include carrier-type excipients, sustained-release excipients, and trace elements mixed in a mass ratio of 6~8:1.5~3:0.5~1.

2. The Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables according to claim 1, characterized in that, The *Staphylococcus wartii* strain was obtained from the China General Microbiological Culture Collection Center (CGMCC), with the accession number CGMCC1.2824.

3. The Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables according to claim 1, characterized in that, The carrier-type auxiliary materials include diatomaceous earth, attapulgite, and wheat bran mixed in a mass ratio of 1~3:1~3:

1.

4. The Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables according to claim 1, characterized in that, The sustained-release excipients include chitosan, humic acid, and amino acid powder mixed in a mass ratio of 1~2:1~2:

1.

5. The Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables according to claim 1, characterized in that, The trace elements include zinc sulfate, FeEDTA, manganese sulfate, cobalt chloride, and sodium molybdate mixed in a mass ratio of 2~4:2~4:1~2:1~2:1~2.

6. The Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables according to claim 1, characterized in that, The desiccant comprises trehalose, lactose, glycerol, and dimethyl sulfoxide mixed in a mass ratio of 1:1 to 2:1 to 2:2 to 4.

7. A method for preparing a Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables as described in any one of claims 1-6, characterized in that, Includes the following steps: Step 1, Primary seed culture: Inoculate Staphylococcus warwick into the seed culture medium and culture it in an incubator at 25-35℃ with shaking for 18-30 hours at a speed of 150-200 rpm to obtain the primary seed culture; Step 2, Secondary seed culture: Inoculate the primary seed culture into the primary seed tank at an inoculation rate of 10-20%, and culture under the following conditions: temperature 25-35℃, rotation speed 150-200rpm, pH 6.5-7.2, dissolved oxygen 20-50%, for 18-30 hours to obtain the secondary seed culture; Step 3: Fermentation tank cultivation: Inoculate the secondary seed liquid (10-20% by volume) and Pythium spp. (1% by volume) into the fermentation tank. Cultivation conditions are: temperature 25-35℃, rotation speed 150-200 rpm, pH 6.5-7.2, and cultivation for 20-36 hours until Pythium spp. is no longer detected in the fermentation liquid. Step 4, bacterial culture treatment: Centrifuge the fermentation broth, adjust the solid content of the Staphylococcus wartii bacterial culture to 60-80%, and add 1-10% by mass of a desiccant to the adjusted Staphylococcus wartii bacterial culture to obtain bacterial slurry; Step 5, Granulation and Drying: Mix the bacterial slurry with the excipients and granulate. Vacuum dry the solid particles at a temperature of 30~50℃ for 10~20 hours to obtain the solid product.

8. The method for preparing the Staphylococcus wartii inoculant for inhibiting Pythium spp. in fruits and vegetables according to claim 7, characterized in that, The seed culture medium in step one is LB medium.

9. The method for preparing the Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables according to claim 7, characterized in that, Both the primary seed tank in step two and the fermentation tank in step three are composed of the following components: glucose 2~5g / L, corn steep liquor 2~5g / L, molasses 0.5~1g / L, (NH4)SO4 0.3~0.8g / L, K2HPO4 0.1~0.5g / L, NaH2PO4 0.1~0.5g / L, MnSO4·H2O 0.01~0.05g / L, FeSO4·7H2O 0.01~0.05g / L, Na2MoO4 0.01~0.05g / L, MgSO4·7H2O 0.01~0.05g / L, and CoCl2 0.01~0.05g / L.

10. The application of a Staphylococcus warwick inoculant for inhibiting Pythium spp. in fruits and vegetables as described in any one of claims 1-6, characterized in that, It can be used as a base fertilizer or top dressing, with an application rate of 1-10 kg / mu.

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