A citrus planting method for reducing huanglongbing

Abstract

The application discloses a citrus planting method for reducing Huanglongbing, and is implemented according to the following process: selecting seedlings without Huanglongbing pathogenic bacteria through molecular detection, pre-treating root systems and branch and trunk epidermis by soaking in a treatment solution of an osmotic regulator and chelated trace elements, deeply ploughing a land plot, applying a composite modifier and then covering a film to be closed, digging a planting hole according to a preset plant spacing, planting the treated seedlings, backfilling a mixed substrate of microwave-disinfected cultivated soil and biochar in layers, irrigating a root-fixing nutrient solution, spraying a disease-resistant nutrient agent every preset period, arranging a trapping device containing a sex pheromone and a contact-killing agent, and supplementing a soil repair agent. The application forms a closed loop from seedling pretreatment, land plot improvement, planting protection to growth period management and postharvest maintenance through a whole-process collaborative prevention and control scheme, solves the limitation of single prevention and control in the prior art, improves the disease resistance of seedlings and the soil bacteriostatic capacity through special functional formulations, and effectively removes potential pathogenic bacteria and transmission media in each link.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of citrus disease prevention, in particular to a citrus planting method for reducing Huanglongbing. BACKGROUND

[0002] In the current field of citrus planting, the prevention and control of Huanglongbing mainly relies on single technical means. The common methods include planting with conventional disease-free seedlings, spraying antibacterial agents in the field, basic ploughing and weeding of the planting plot, and setting up simple insect prevention devices around the plot to reduce the activity of insect transmission media. These techniques can reduce the probability of Huanglongbing to some extent and have become a relatively common prevention and control mode in the industry, which is widely used in major citrus producing areas.

[0003] However, the existing technology has obvious deficiencies. On the one hand, conventional disease-free seedlings lack targeted pretreatment, and the disease resistance of seedlings cannot be improved, and the residual pathogenic bacteria in the soil cannot be effectively removed after ploughing the plot. On the other hand, the use of agents in field management and insect prevention measures are not well connected, and it is difficult to form a whole cycle prevention and control system, which leads to the recurrence of Huanglongbing during the growth period or after harvesting. At the same time, the influence of traditional technology on soil ecology and long-term growth of plants is not considered, which easily leads to soil quality decline or weakened plant stress resistance. SUMMARY

[0004] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0005] In view of the above and / or existing problems in a citrus planting method for reducing Huanglongbing, the present application is proposed.

[0006] To solve the above technical problems, the present application provides the following technical scheme: a citrus planting method for reducing Huanglongbing, which comprises the following steps:

[0007] Select seedlings without Huanglongbing pathogen detected by molecular detection, and gradient soak the root system and branch bark with a treatment solution of osmotic regulator and chelated trace elements at a predetermined ratio for pretreatment. Then, place the pretreated seedlings in a sterile environment and cultivate them with a substrate containing humic acid and probiotic bacteria until new shoots germinate and grow healthy.

[0008] After deep ploughing the plot, apply a composite modifier composed of mature organic fertilizer, mineral source bacteriostatic agent and soil structure modifier, and then cover the film and seal it.

[0009] Digging planting hole according to preset plant spacing, laying isolation layer of insect-proof fiber film and slow-release insect repellent on hole bottom;

[0010] After implanting the seedlings, backfilling the mixed substrate of microwave sterilized cultivated soil and biochar, and irrigating the rooting nutrient solution containing amino acid and rooting promoter after planting.

[0011] Periodically checking and removing diseased and dead plants and weeds, and spraying disease-resistant nutrient agent containing plant-derived disease resistance inducer, trace element foliar fertilizer and adjuvant every preset period; setting up trapping device containing sex pheromone and contact-killing agent, and immersing operation tools in solution containing quaternary ammonium salt disinfectant before field operation.

[0012] After harvesting, pruning off branches with potential pathogenic bacteria, spraying protection liquid containing broad-spectrum antibacterial agent and plant growth regulator, and secondary deep ploughing the field and supplementing soil repair agent containing organic fertilizer and microbial agent.

[0013] As a preferred scheme of the citrus planting method for reducing Huanglongbing, the osmotic regulator is at least one of polyethylene glycol, propylene glycol or glycerol, and the chelated trace element is a mixture of chelated iron, chelated zinc and chelated manganese in a mass ratio of (1-3):(1-2):1.

[0014] As a preferred scheme of the citrus planting method for reducing Huanglongbing, the mass fraction of humic acid in the substrate containing humic acid and probiotic bacteria is 5%-15%, the probiotic bacteria are a complex bacterial group composed of Bacillus subtilis and Paenibacillus mucilaginosus in a ratio of (2-3):1 in terms of colony number, and the effective viable bacterial count of the probiotic bacteria in the substrate is not less than 1×10 8 CFU / g.

[0015] As a preferred scheme of the citrus planting method for reducing Huanglongbing, the mass ratio of the composted organic fertilizer, the mineral source antibacterial agent and the soil structure modifier in the complex modifier is (8-12):(1-2):(0.5-1), the mineral source antibacterial agent is made of montmorillonite or zeolite powder loaded with antibacterial components, and the soil structure modifier is vermiculite or perlite.

[0016] As a preferred scheme of the citrus planting method for reducing Huanglongbing, the slow-release insect repellent in the isolation layer is a mixture of pyrethrin or azadirachtin and a slow-release carrier in a mass ratio of (1-3):(10-20), the slow-release carrier is starch-based microspheres or chitosan microspheres, and the insect-proof fiber film is a polyester fiber film pretreated with an insect repellent.

[0017] As a preferred scheme of the citrus planting method for reducing Huanglongbing, in the mixed matrix of the cultivated soil and the biochar, the mass fraction of the biochar is 5-15%, and the biochar is made of citrus branches or wood waste through high-temperature carbonization and activation, and a phosphoric acid solution with a mass fraction of 5-10% is used for activation treatment in the activation process.

[0018] As a preferred scheme of the citrus planting method for reducing Huanglongbing, in the anti-disease nutrient agent, the plant-derived anti-disease inducer is at least one of salicylic acid, methyl jasmonate or chitosan oligosaccharide, the adjuvant is a non-ionic surfactant, and the mass ratio of the plant-derived anti-disease inducer, the trace element foliar fertilizer and the adjuvant is (1-2):(5-8):(0.5-1).

[0019] As a preferred scheme of the citrus planting method for reducing Huanglongbing, in the protective solution, the broad-spectrum antibacterial agent is kasugamycin or zinc thiazole, the plant growth regulator is brassinolide or gibberellin, and the mass ratio of the broad-spectrum antibacterial agent and the plant growth regulator is (5-10):(1-2); in the soil repair agent, the mass ratio of the organic fertilizer and the microbial agent is (10-15):(1-2), and the microbial agent is a composite microbial agent of nitrogen-fixing bacteria and phosphorus-dissolving bacteria.

[0020] In a second aspect, some embodiments of the present application provide an electronic device, including: one or more processors; a storage device having one or more programs stored thereon, when the one or more programs are executed by the one or more processors, the one or more processors implement the method described in any of the implementation manners of the first aspect.

[0021] In a third aspect, some embodiments of the present application provide a computer readable medium having a computer program stored thereon, wherein the program is executed by a processor to implement the method described in any of the implementation manners of the first aspect.

[0022] The present application forms a closed loop through the whole-process collaborative prevention and control scheme from seedling pretreatment, land improvement, planting protection to growth period management and post-harvest maintenance, which not only solves the limitations of single prevention and control in the prior art, but also improves the disease resistance of seedlings and the soil bacteriostatic ability through special functional formulations, effectively removes potential pathogenic bacteria and transmission media at each link. At the same time, the scheme takes into account soil ecological restoration and long-term health of plants, avoids the adverse effects of the prior art on the environment and plants, significantly reduces the risk of Huanglongbing, and ensures the stability and sustainability of citrus planting. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A flow structure diagram of the citrus planting method for reducing Huanglongbing in Example 1;

[0024] Figure 2 An electronic structure diagram for implementing the railway cutting sand retaining wall design optimization method based on simulation in Example 8.

[0025] Figure 2 In the figure, 301 is a processing device, 302 is a ROM, 303 is a RAM, 304 is a bus, 305 is an I / O interface, 306 is an input device, 307 is an output device, 308 is a storage device, and 309 is a communication device. DETAILED DESCRIPTION

[0026] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0027] Example 1

[0028] Reference Figure 1 For the first embodiment of the present application, the embodiment provides a citrus planting method for reducing Huanglongbing, which is implemented according to the following process:

[0029] The seedlings without Huanglongbing pathogen are selected, the root system and branch bark are gradiently soaked with a treatment liquid of osmotic regulator and chelated trace elements according to a preset ratio for pretreatment, and then the pretreated seedlings are placed in a sterile environment and cultivated in a substrate containing humic acid and probiotic flora until new shoots are germinated and healthy; the osmotic regulator is at least one of polyethylene glycol, propylene glycol or glycerol, and the chelated trace elements are a mixture composed of chelated iron, chelated zinc and chelated manganese according to a mass ratio of (1-3):(1-2):1; in the substrate containing humic acid and probiotic flora, the mass fraction of humic acid is 5%-15%, and the probiotic flora is a complex bacterial flora composed of Bacillus subtilis and Paenibacillus gummosus according to a ratio of (2-3):1 in terms of colony number, and the effective viable bacterial number of the probiotic flora in the substrate is not less than 1×10 8 CFU / g.

[0030] After deep ploughing of the land, a composite modifier composed of mature organic fertilizer, mineral source bacteriostatic agent and soil structure modifier is applied, and then a film is covered for sealing. In the composite modifier, the mass ratio of the mature organic fertilizer, the mineral source bacteriostatic agent and the soil structure modifier is (8-12):(1-2):(0.5-1), wherein the mineral source bacteriostatic agent is made of montmorillonite or zeolite powder loaded with antibacterial components, and the soil structure modifier is vermiculite or perlite.

[0031] A planting hole is excavated according to a preset plant spacing, and an isolation layer composed of a pest-resistant fiber film and a slow-release insect repellent is laid on the bottom of the hole; in the isolation layer, the slow-release insect repellent is a mixture of pyrethrin or azadirachtin and a slow-release carrier according to a mass ratio of (1-3):(10-20), the slow-release carrier is a starch-based microsphere or a chitosan microsphere, and the pest-resistant fiber film is a polyester fiber film pretreated with a pest-resistant agent.

[0032] The seedlings after the implanting treatment are backfilled with a mixed substrate of the microwave sterilized cultivated soil and the biochar, and after planting, a rooting nutrient solution containing amino acids and rooting promoters is poured. In the mixed substrate of the cultivated soil and the biochar, the mass fraction of the biochar is 5%-15%, and the biochar is made of citrus branches or wood waste through high-temperature carbonization and activation, and a phosphoric acid solution with a mass fraction of 5%-10% is used for activation treatment in the activation process.

[0033] Periodically, the diseased residues and weeds are patrolled and cleared, and every preset period, a disease-resistant nutrient agent containing a plant-derived disease-resistant inducer, a trace element foliar fertilizer and an auxiliary agent is sprayed; a trapping device containing a sex pheromone and a contact-killing agent is arranged, and before field operation, the operation tools are soaked in a solution containing a quaternary ammonium salt disinfectant. In the disease-resistant nutrient agent, the plant-derived disease-resistant inducer is at least one of salicylic acid, methyl jasmonate or chitosan oligosaccharide, the auxiliary agent is a non-ionic surfactant, and the mass ratio of the plant-derived disease-resistant inducer, the trace element foliar fertilizer and the auxiliary agent is (1-2):(5-8):(0.5-1).

[0034] After fruit picking, the branches with potential pathogenic bacteria are pruned, a protective solution containing a broad-spectrum antibacterial agent and a plant growth regulator is sprayed, the land is ploughed again, and a soil repair agent containing organic fertilizer and microbial agents is supplemented.

[0035] In the protective solution, the broad-spectrum antibacterial agent is kasugamycin or zinc thiazole, the plant growth regulator is brassinolide or gibberellin, and the mass ratio of the broad-spectrum antibacterial agent and the plant growth regulator is (5-10):(1-2); in the soil repair agent, the mass ratio of the organic fertilizer and the microbial agent is (10-15):(1-2), and the microbial agent is a composite microbial agent of nitrogen-fixing bacteria and phosphorus-dissolving bacteria.

[0036] Embodiment 2

[0037] The second embodiment of the present application is different from the first embodiment in that it further includes a test preparation and implementation process.

[0038] The test is located in a professional seedling base in a main citrus production area in the south, the base is provided with a temperature control seedling shed, a molecular detection laboratory and a precise irrigation system, and the test period is 45 days (covering the key period of new shoot germination of citrus seedlings). The tested material is selected from one-year-old Wohuan seedlings, the variety has a wide planting area in the local area, and has a medium sensitivity to Huanglongbing, and is representative. Before the test, 180 seedlings with consistent plant height, same stem thickness and no diseases and pests are selected from the base nursery, the Candidatus Liberibacter asiaticus of all the seedlings is detected by real-time fluorescent quantitative PCR technology, it is confirmed that all the seedlings are negative, the initial pathogenic bacteria interference is excluded, and the test baseline is unified.

[0039] Test reagent preparation: Osmotic regulator is selected from polyethylene glycol, propylene glycol and glycerol; chelated trace elements are selected from EDTA chelated iron, EDTA chelated zinc and EDTA chelated manganese; deionized water is self-made in the laboratory. According to the defined "osmotic regulator is at least one of polyethylene glycol, propylene glycol or glycerol, and chelated trace elements are composed of chelated iron, chelated zinc and chelated manganese in a mass ratio of (1-3):(1-2):1", six groups of formulations are designed, wherein group 1 is a blank control group (only treated with deionized water), and groups 2-6 are test groups, and the specific grouping is as follows: group 1: deionized water (without osmotic regulator and chelated micro-fertilizer);

[0040] Group 2: Osmotic regulator (polyethylene glycol) + chelated micro-fertilizer (1:1:1);

[0041] Group 3: Osmotic regulator (polyethylene glycol) + chelated micro-fertilizer (2:1:1);

[0042] Group 4: Osmotic regulator (polyethylene glycol) + chelated micro-fertilizer (3:2:1);

[0043] Group 5: Osmotic regulator (polyethylene glycol: propylene glycol = 1:1) + chelated micro-fertilizer (2:1:1);

[0044] Group 6: Osmotic regulator (polyethylene glycol: glycerol = 1:1) + chelated micro-fertilizer (2:1:1).

[0045] Preparation process of treatment solution (take group 4 as an example): first calculate the amount of each component, set the total mass of the treatment solution to be 10 kg, then the total mass of chelated trace elements is 120 g (accounting for 1.2%), according to the ratio of 3:2:1, the mass of chelated iron is 60 g, the mass of chelated zinc is 40 g, and the mass of chelated manganese is 20 g; the amount of osmotic regulator is 100 g. Add the above reagents to the deionized water in turn, stir for 30 minutes with a magnetic stirrer until completely dissolved, and measure the pH value of the solution to be 6.5±0.2, which meets the tolerance range of citrus root system.

[0046] Seedling treatment and cultivation: immerse the root system and lower part of the branches and stems of the seedlings in the corresponding treatment solution, and use gradient temperature immersion method, stir the treatment solution gently every 15 minutes during the immersion process to ensure uniform contact. After immersion, the seedlings are taken out and drained, and then transferred to the seedling pots in the sterile seedling shed, and the seedling pots are uniformly sized with an upper diameter of 20 cm, a lower diameter of 15 cm and a height of 18 cm. Each pot is filled with 1.5 kg of seedling substrate containing humic acid and probiotic bacteria. The environmental parameters of the seedling shed are controlled as follows: daytime temperature 25±2℃, nighttime temperature 22±1℃, relative humidity 65±5%, daily light for 12 hours, and water is poured once a day by using a drip irrigation system. When the cultivation is carried out for 45 days, the indicators of each group of seedlings are measured, and 10 seedlings are selected from each group for artificial inoculation of Huanglongbing pathogen, and the inoculation is continued for 30 days, and the incidence rate is counted.

[0047] Table 1 Effects of different seedling treatment liquid formulations on the growth and disease resistance of Citrus sinensis seedlings

[0048]

[0049] As can be clearly seen from the data in Table 1, the blank control group (group 1) performed the worst in all indicators, with only 3.2 new shoots per plant, an average new shoot length of 8.5 cm, a root fresh weight of 28.6 g per plant, a leaf SPAD value of 32.1, a POD activity of 85.3 U / (g·min), and a disease incidence of 42.5% after artificial inoculation with the Huanglongbing pathogen. This result is consistent with the current situation in the prior art, i.e., only using water to simply treat seedlings without targeted functional component supplementation, highlighting the core deficiency of the prior art that cannot effectively improve the growth potential and disease resistance of seedlings - water treatment can only maintain the basic physiological activities of seedlings, cannot enhance root absorption capacity through nutrient supplementation and osmotic regulation, and cannot activate the plant's own disease resistance enzyme system, resulting in seedlings being easily attacked by pathogens during subsequent growth.

[0050] Comparing the test groups (groups 2-6) with the control group (group 1), all indicators of the test groups were significantly improved, proving that the seedling treatment liquid formulation of the present application has a positive effect on the growth and disease resistance of citrus seedlings, and the effects of different formulations differ significantly. Group 4 performed the best, with specific data comparison and analysis as follows: in terms of growth indicators, group 4 had 6.3 new shoots per plant, an increase of 96.9% compared to group 1, an increase of 40.0% compared to group 2, and an increase of 23.5% compared to group 3; the average new shoot length was 15.3 cm, an increase of 79.9% compared to group 1, an increase of 36.6% compared to group 2, and an increase of 19.5% compared to group 3; the root fresh weight was 46.2 g per plant, an increase of 61.5% compared to group 1, an increase of 29.0% compared to group 2, and an increase of 16.9% compared to group 3. This indicates that polyethylene glycol as an osmotic regulator can effectively destroy the cutin layer structure of the root epidermis, increase cell membrane permeability, and promote the absorption of chelated trace elements; and when chelated iron, chelated zinc, and chelated manganese are in a ratio of 3:2:1, absorption competition among trace elements can be avoided, achieving synergistic supplementation - iron is a key component of chlorophyll synthesis, zinc is involved in auxin synthesis, and manganese can activate photosynthetic enzyme activity, and reasonable ratios of the three can significantly improve leaf photosynthetic efficiency and root growth activity, solving the problem of "chaotic trace element ratios and low absorption efficiency" in the prior art.

[0051] In terms of disease resistance indicators, the leaf POD activity of group 4 is 165.7 U / (g min), which is increased by 94.2% compared with group 1, increased by 19.7% compared with group 3, increased by 8.8% compared with group 5, and increased by 11.6% compared with group 6; the incidence after artificial inoculation is 12.8%, which is reduced by 69.9% compared with group 1, reduced by 54.8% compared with group 2, reduced by 40.7% compared with group 3, reduced by 22.4% compared with group 5, and reduced by 25.6% compared with group 6. The POD enzyme is a key defense enzyme in plant disease resistance, and its activity directly reflects the resistance of the plant to the pathogen, and the high POD activity of group 4 shows that the formula can effectively activate the innate immune mechanism of the plant and enhance the inhibition of the Huanglongbing pathogen; and the low incidence further verifies the effectiveness of the formula in actual prevention and control, which is in sharp contrast with the prior art "only relying on external fungicides, and unable to activate the plant disease resistance", and embodies the creativity of the application - through the double mechanism of "osmotic regulation + nutrition strengthening", the growth basis of the seedling is improved, and the disease resistance is enhanced, realizing the change from "passive defense" to "active immunity".

[0052] In addition, group 5 and group 6 use mixed penetrating agents (polyethylene glycol + propylene glycol / glycerol), although the indicators are better than groups 2 and 3, but not as good as group 4, the reason is that the molecular structures of different components in the mixed penetrating agent are different, the number of hydroxyl groups of propylene glycol and glycerol is relatively large, which is easy to form hydrogen bonds with chelated trace elements, thereby reducing the free mobility of trace elements and affecting the absorption efficiency; and group 2 has a relatively insufficient iron content due to the 1:1:1 ratio of chelated micro-fertilizers, which limits the synthesis of chlorophyll, and the SPAD value is only 36.5, thereby affecting the accumulation of photosynthetic products, resulting in low POD activity and high incidence. These data differences fully prove that the "osmotic regulator selected as polyethylene glycol, and chelated trace elements in a ratio of 3:2:1" defined in the application is not randomly set, but achieves synergistic effect through component adaptability and ratio optimization, filling the gap in the prior art "without clear component ratio of seedling treatment liquid, and unstable prevention and control effect", and providing a precise and efficient technical solution for citrus seedling pretreatment.

[0053] Example 3

[0054] The third embodiment of the application also includes test preparation and implementation process:

[0055] The test was carried out in a citrus seedling test station in a subtropical climate zone, and the test period was set for 60 days (covering the key stages of citrus seedling root development and new shoot lignification). The test material selected was one-year-old sugar orange seedlings, which had sensitive root systems and high requirements for the substrate environment, and could more accurately reflect the differences in substrate formulations. Before the test, 240 seedlings with a height of 28±2 cm, a stem diameter of 0.45±0.05 cm, and no mechanical damage were selected from the nursery, and after real-time fluorescent quantitative PCR detection confirmed that there was no Candidatus Liberibacter asiaticus, they were randomly divided into 6 groups, with 40 seedlings in each group. Group 1 was the blank control group (using conventional garden soil substrate), and groups 2-6 were the test groups (using substrates containing different proportions of humic acid and probiotic bacteria).

[0056] Test material preparation: Humic acid selected from weathered coal-derived biochemical humic acid (humic acid content ≥70%, pH 5.5-6.5); probiotic bacteria selected Bacillus subtilis (viable bacterial count ≥2×10 0 CFU / g) and Paenibacillus gummosus (viable bacterial count ≥1×10 0 CFU / g); conventional garden soil substrate was local cultivated soil; the specifications of the seedling pots were uniform, with an upper diameter of 22 cm, a lower diameter of 16 cm, and a height of 20 cm, and each pot contained 2 kg of substrate. According to the design of "humic acid mass fraction 5%-15%, probiotic bacteria consisting of Bacillus subtilis and Paenibacillus gummosus in a ratio of 2-3:1, with an effective viable bacterial count of not less than 1×10 8 CFU / g", the formulations were specifically grouped as follows:

[0057] Group 1: Conventional garden soil substrate (without humic acid and probiotic bacteria);

[0058] Group 2: Humic acid mass fraction 5% + probiotic bacteria (bacterial count ratio 1:1, effective viable bacterial count 0.8×10 8 CFU / g);

[0059] Group 3: Humic acid mass fraction 10% + probiotic bacteria (bacterial count ratio 2:1, effective viable bacterial count 1×10 8 CFU / g);

[0060] Group 4: Humic acid mass fraction 10% + probiotic bacteria (bacterial count ratio 3:1, effective viable bacterial count 1.2×10 8 CFU / g);

[0061] Group 5: Humic acid mass fraction 15% + probiotic bacteria (bacterial count ratio 2:1, effective viable bacterial count 1×10 8 CFU / g);

[0062] Group 6: Humic acid mass fraction 10% + single Bacillus subtilis (effective viable bacterial count 1×10 8 CFU / g).

[0063] Matrix preparation process (take group 4 as an example): the first step is to calculate the amount of raw materials, the total mass of each pot is 2 kg, 200 g of humic acid needs to be added, and the remaining 1800 g is regular garden soil; the effective viable count of probiotic bacteria needs to meet 1.2 x 10 8 CFU / g, according to the ratio of colony number 3:1, Bacillus subtilis needs to provide 0.9 x 10 8 CFU / g, and Paenibacillus mucilaginosus provides 0.3 x 10 8 CFU / g, converted into the amount of commercial bacterial agent: 18 g of Bacillus subtilis agent and 6 g of Paenibacillus mucilaginosus agent, which are mixed and fully mixed with humic acid and regular garden soil, supplemented with deionized water by spraying method, the water content of the matrix is adjusted to 60%, and the matrix is sealed and piled for 24 hours to activate the bacterial population and ensure uniform distribution and active state of the bacterial population.

[0064] Seedling planting and cultivation management: plant each group of seedlings into the corresponding matrix of the seedling pot, the planting depth is appropriate to make the root soil lump level with the surface of the matrix, and irrigation is carried out after planting. The cultivation environment control: the temperature in the seedling shed is 26±2℃ during the day and 23±1℃ at night, the relative humidity is 60%-70%, the daily light is 13h, intermittent drip irrigation is used to avoid water accumulation in the matrix. Cultivate to the 60th day, measure the root morphology, photosynthetic parameters and disease resistance related indexes of each group of seedlings, and select 15 seedlings from each group for artificial inoculation of Huanglongbing pathogen, continue to cultivate for 35 days after inoculation, and count the incidence.

[0065] Table 2 Effect of different seedling matrix formulations on the growth and disease resistance of sugar orange seedlings

[0066]

[0067] From the data in Table 2, the blank control group is significantly behind in all indicators, with a total root length of only 48.6 cm / plant, a root activity of 18.5 μg / (g·h), a net photosynthetic rate of 5.2 μmol / (m²·s), and a disease incidence of 48.3% after artificial inoculation, which is highly consistent with the current situation of "using ordinary garden soil for seedling raising, lacking humic acid and functional bacterial population supplement", exposing the core defect of the existing technology-the low organic matter content and single bacterial population structure of regular garden soil, which cannot provide sufficient nutrient supply and microecological protection for seedlings, leading to poor root development, weak photosynthetic capacity, and poor resistance to Huanglongbing pathogen.

[0068] The test groups (groups 2-6) are all better than the control group, and group 4 performs best, and the specific data comparison and analysis are as follows: in terms of root development indexes, the total root length of group 4 is 92.4 cm / plant, which is increased by 90.1% compared with group 1, increased by 41.5% compared with group 2, and increased by 17.7% compared with group 3; the average root diameter is 0.51 mm, which is increased by 59.4% compared with group 1, and increased by 6.2% compared with group 5; the root activity is 38.9 μg / (g h), which is increased by 110.3% compared with group 1, and increased by 35.5% compared with group 6. This result shows that 10% humic acid can improve the structure of the substrate granules, increase the porosity, and provide sufficient space for root growth, and the functional groups such as carboxyl and hydroxyl of humic acid can chelate mineral elements in the soil, and improve the nutrient utilization rate; and when the bacillus subtilis and the paste-like bacillus are in a ratio of 3:1, a synergistic effect can be formed - the bacillus subtilis can secrete antibacterial substances to inhibit the growth of pathogenic bacteria, and the paste-like bacillus can decompose silicates in the substrate to release silicon elements to enhance the strength of the root cell wall, and the combination of the two can significantly promote the root development, and solve the problem of "imbalance of substrate microecology and insufficient root activity" in the prior art.

[0069] In terms of photosynthesis and disease resistance indexes, the net photosynthetic rate of group 4 is 9.8 μmol / (m² s), which is increased by 88.5% compared with group 1, increased by 15.3% compared with group 3, and increased by 7.7% compared with group 5; the PAL activity of the leaf is 135.7 U / (g h), which is increased by 117.8% compared with group 1, increased by 58.5% compared with group 2, and increased by 37.8% compared with group 6; the incidence rate after artificial inoculation is 14.2%, which is reduced by 70.6% compared with group 1, reduced by 36.9% compared with group 3, and reduced by 23.7% compared with group 5. PAL enzyme is a key rate-limiting enzyme for plant synthesis of phytoalexin and lignin, and the higher the activity is, the stronger the chemical defense ability of the plant is, and the high PAL activity of group 4 shows that the substrate formula can effectively activate the secondary metabolic defense system of the seedling; and the high net photosynthetic rate can accumulate more photosynthetic products for the seedling, and provide energy and material basis for the disease resistance, which is in sharp contrast with the prior art "only relying on external fertilization, and unable to improve plant disease resistance from the microecological and physiological metabolic level", and embodies the creativity of the present application - through the double paths of "humic acid improving substrate structure + complex microbial community regulating microecology", the growth environment of the seedling is optimized, and the disease resistance mechanism is activated, and the synergistic effect of "environment optimization-physiological strengthening-disease resistance improvement" is realized.

[0070] Further analysis of the differences of groups 2, 5 and 6: group 2 has a limited effect of medium improvement due to the humic acid content of only 5%, and the Bacillus subtilis content is insufficient when the bacterial flora ratio is 1:1, and the antibacterial ability is weak, so the incidence rate is 35.2%; group 5 has a humic acid content of 15% which is too high, resulting in that the pH value of the medium is reduced to below 5.0, which inhibits the absorption of calcium, magnesium and other elements by the root system, and the net photosynthetic rate is 7.1% lower than that of group 4; group 6 uses single Bacillus subtilis, and lacks the phosphorus dissolving and potassium releasing effect of gelatinous Paenibacillus, and the root activity is only 28.7 μg / (g·h), which is 26.2% lower than that of group 4. These data differences fully prove that the "humic acid mass fraction of 10%, and the bacterial flora bacterial colony number ratio of 3:1" defined in the application is not randomly set, but is optimized through the adaptability of the medium physicochemical properties and the function of the bacterial flora, so as to realize the maximization of the effect, and fill the gap in the prior art that "the humic acid and bacterial flora ratio of the seedling medium is not clear, and the seedling quality is unstable", and provide a scientific and efficient technical scheme for citrus disease-free seedling cultivation.

[0071] Example 4

[0072] The fourth embodiment of the application also includes the preparation and implementation process of the test:

[0073] The test site is located in a continuous cropping plot in a southern citrus old production area. The plot has problems such as residual Huanglongbing pathogen in the soil due to long-term planting of citrus, soil compaction, and low organic matter content, which meets the typical scene of "poor soil quality and high residual pathogen" in the prior art. The test cycle is set to 120 days, and the test material is one-year-old navel orange seedlings, a total of 240, which are randomly divided into 6 groups, 40 in each group. Group 1 is the blank control group (no improvement agent is applied), and groups 2-6 are test groups (different ratios of composite improvement agents are applied).

[0074] Test material preparation: the composite improvement agent is composed of composted organic fertilizer, mineral source bacteriostatic agent and soil structure improvement agent. The composted organic fertilizer is cow manure compost (organic matter content ≥45%, pH value 7.0-7.5, and composting degree reaches complete composting); the mineral source bacteriostatic agent is montmorillonite loaded with antibacterial components (montmorillonite purity ≥90%, antibacterial component loading amount ≥5%); and the soil structure improvement agent is vermiculite. The formulation is designed according to the "mass ratio of composted organic fertilizer, mineral source bacteriostatic agent and soil structure improvement agent is (8-12):(1-2):(0.5-1)", and the specific grouping is as follows:

[0075] Group 1: blank control (no composite improvement agent is applied, only conventional ploughing);

[0076] Group 2: mass ratio 8:1:0.5 (composted organic fertilizer: mineral source bacteriostatic agent: soil structure improvement agent);

[0077] Group 3: mass ratio 10:1:0.5;

[0078] Group 4: mass ratio 10:2:1;

[0079] Group 5: mass ratio 12:2:1;

[0080] Group 6: single composted organic fertilizer (the application amount is consistent with that of composted organic fertilizer in group 4).

[0081] Test plot treatment and planting: first, divide the test plot into six plots, each with an area of 20 m2, and set a 1 m wide isolation belt between plots to avoid cross contamination of the amendment. Calculate the plot amount according to the application amount of 2000 kg / mu. For example, group 4, according to the mass ratio of 10:2:1, composted organic fertilizer 60 kg x (10 / 13) ≈ 46.15 kg, mineral source bacteriostatic agent 60 kg x (2 / 13) ≈ 9.23 kg, soil structure modifier 60 kg x (1 / 13) ≈ 4.62 kg, mix them evenly and reserve.

[0082] Plot improvement process: deep plough each group plot, evenly spread the corresponding composite amendment on the soil surface, then plough again to ensure that the amendment is fully mixed with the 0-30 cm plough layer soil; then use polyethylene film for sealing treatment, make sure the film is tightly attached to the soil surface during mulching, and the edges are compacted with soil to prevent air leakage. After 30 days of sealing, remove the film and measure the soil physical and chemical properties and pathogen residue, then dig planting holes according to the plant spacing of 2m x 3m, plant navel orange seedlings in the holes, and irrigate with rooting water after planting.

[0083] Post-planting management: after planting, carry out unified field management, including intermittent irrigation and manual weeding, without applying other fungicides or fertilizers to ensure that the test results are only caused by differences in composite amendments. On the 90th day after planting, measure the soil indicators, plant growth indicators and leaf disease resistance indicators of each group, and at the same time, count the natural disease incidence of each group of plants.

[0084] Table 3 Effect of different composite amendment formulations on citrus planting plot soil and plants

[0085]

[0086] As can be seen from the data in Table 3, the soil and plant indicators of the blank control group (group 1) are the worst, with soil organic matter content of only 1.0%, bulk density of 1.45 g / cm3, pathogen detection rate of 32%, plant natural disease incidence of 28.5%, and new shoot growth of 12.5 cm / plant, which is completely consistent with the current situation that "continuous cropping plots are not specially improved, the soil quality is poor, the pathogen residue is high, which leads to weak plant growth and high disease risk", highlighting the core defect of the prior art in the plot pretreatment link - only relying on conventional ploughing, which cannot improve soil structure, supplement organic matter, and effectively remove residual pathogens, laying a hidden danger for Huanglongbing.

[0087] The test groups (groups 2-6) are all better than the control group, and group 4 performs best, and the specific data comparison and analysis are as follows: in terms of soil indicators, the soil organic matter content of group 4 is 2.5%, which is increased by 150% compared with group 1, increased by 38.9% compared with group 2, and increased by 19.0% compared with group 6; the soil bulk density is 1.18 g / cm³, which is reduced by 18.6% compared with group 1 and reduced by 5.6% compared with group 3; the detection rate of soil pathogenic bacteria is 8.5%, which is reduced by 73.4% compared with group 1 and reduced by 16.7% compared with group 5. This result shows that the compound modifier with a ratio of 10:2:1 can improve the soil quality through the synergistic effect of each component: the mature organic fertilizer provides sufficient organic matter, improves soil fertility and water and fertilizer retention capacity; the mineral source bacteriostatic agent effectively reduces the number of pathogenic bacteria through physical adsorption and chemical bacteriostasis; and the soil structure modifier improves soil aeration by increasing soil porosity, reducing bulk density, and solves the problem of "single improvement measure limited effect, unable to consider soil fertility, structure and bacteriostasis" in the prior art.

[0088] In terms of plant growth and disease resistance indicators, the new shoot growth of group 4 is 28.4 cm / plant, which is increased by 127.2% compared with group 1, increased by 25.7% compared with group 3, and increased by 59.6% compared with group 6; the dry matter accumulation is 92.5 g / plant, which is increased by 102.8% compared with group 1 and increased by 48.5% compared with group 2; the chitinase activity of leaf is 96.4 U / (g min), which is increased by 99.6% compared with group 1 and increased by 6.8% compared with group 5 (90.3 U / (g min)); the natural incidence of plants is only 6.8%, which is reduced by 76.1% compared with group 1 and reduced by 64.6% compared with group 2. Chitinase is a key enzyme for plants to degrade pathogenic bacterial cell walls, and its activity directly reflects the plant's ability to remove pathogenic bacteria. The high chitinase activity of group 4 shows that the improved soil environment not only provides sufficient nutrients for plants, but also improves the root microecology and activates the plant's own disease resistance enzyme system, achieving the simultaneous improvement of "soil improvement-plant nutrition-disease resistance", which is in sharp contrast to the prior art "only applying single organic fertilizer can only improve fertility, cannot inhibit bacteria and improve structure, and the plant disease risk is still high", and embodies the creativity of the present application.

[0089] Further analysis of the differences of groups 2, 3 and 5: group 2 has insufficient amounts of mature organic fertilizer and mineral source bacteriostatic agent in the modifier ratio, limited improvement of soil organic matter, poor bacteriostatic effect, so the detection rate of pathogenic bacteria is 21.5%, the incidence rate is 19.2%; group 3 increases the amount of mature organic fertilizer, but the mineral source bacteriostatic agent is still insufficient, the detection rate of pathogenic bacteria is 16.8%, the plant growth is 20.4% lower than that of group 4; group 5 has excessive mature organic fertilizer, which causes the soil pH value to rise to 7.8, inhibits the absorption of iron, zinc and other trace elements by the root system, and the dry matter accumulation is 4.2% lower than that of group 4, and the incidence rate is 22.1% higher than that of group 4. These data differences fully prove that the "mature organic fertilizer: mineral source bacteriostatic agent: soil structure modifier = 10:2:1" defined in the application is not randomly set, but through the precise matching of the amounts of each component, the optimal balance of soil fertility, structure and bacteriostatic effect is achieved, filling the gap in the prior art that "the modifier ratio of the plot is not clear, and the prevention and control effect of the continuous cropping plot is poor", and providing an efficient and comprehensive technical solution for the pretreatment of citrus planting plots.

[0090] Example 5

[0091] The fifth embodiment of the application also includes test preparation and implementation process:

[0092] The test was carried out in an open field in the citrus production area in the south, which is a high-incidence area of Huanglongbing transmission vectors, and meets the typical scenario in the prior art that "after planting, the transmission vectors easily invade the roots, leading to the spread of pathogenic bacteria". The test cycle is set to 90 days, and the test material is selected as one-year-old Wenzhou Citrus seedlings, a total of 240, which are randomly divided into 6 groups, 40 in each group, group 1 is the blank control group (without setting the insect-proof isolation layer), and groups 2-6 are the test groups (using different formulations of insect-proof isolation layers).

[0093] Test material preparation: the insect-proof isolation layer is composed of an insect-proof fiber film and a slow-release repellent. The insect-proof fiber film is selected from polyester fiber film (thickness 0.1 mm, air permeability 500 mL / (m²·s), waterproof treatment); the slow-release repellent is prepared by mixing active ingredients (pyrethrin or azadirachtin, purity ≥95%) and slow-release carriers (starch-based microspheres or chitosan microspheres, particle size 50-100 μm); at the same time, a citrus psylla trap is prepared. According to the "mass ratio of slow-release repellent to slow-release carrier (1-3): (10-20), repellent loading capacity 5-15 g / m²" design formula, the specific grouping is as follows:

[0094] Group 1: blank control (without laying insect-proof isolation layer in planting hole);

[0095] Group 2: insect-proof fiber film + pyrethrin-starch-based microsphere repellent (mass ratio 1:20, loading capacity 5 g / m²);

[0096] Group 3: Insect-proof fiber film + pyrethrin-starch-based microsphere repellent (mass ratio 2:15, loading capacity 10 g / m²);

[0097] Group 4: Insect-proof fiber film + azadirachtin-chitosan microsphere repellent (mass ratio 3:10, loading capacity 15 g / m²);

[0098] Group 5: Insect-proof fiber film + azadirachtin-starch-based microsphere repellent (mass ratio 3:10, loading capacity 15 g / m²);

[0099] Group 6: Single insect-proof fiber film (without adding slow-release repellent).

[0100] Preparation and planting of insect-proof isolation layer: First, prepare the slow-release repellent of each group. For example, for Group 4, take azadirachtin 30 g and chitosan microspheres 100 g according to the mass ratio of 3:10, add deionized water 500 mL, and stir for 30 minutes with a high-speed disperser to make the repellent uniformly adsorbed on the surface of the carrier. Then, dry it in a vacuum drying oven at 60°C until the moisture content is ≤5%, crush it, and store it for later use. Cut the insect-proof fiber film into a circle with a diameter of 60 cm, evenly sprinkle the prepared slow-release repellent, and gently press it to make the repellent adhere to the film surface to form the insect-proof isolation layer.

[0101] Planting process: The test plot is first subjected to conventional deep plowing and leveling, and planting holes are dug according to the plant spacing of 2.5 m x 3 m. Forty seedlings of each group correspond to 40 planting holes. The insect-proof isolation layer corresponding to each group is laid at the bottom of each planting hole, and then the planting hole is filled with sterilized cultivated soil to a depth of 1 / 2, and the citrus seedlings are planted, and the soil is backfilled in layers and gently compacted to ensure that the root system is in close contact with the soil. Each plant is irrigated with 5L of rooting water after planting.

[0102] Post-planting management and monitoring: After planting, uniform field management is carried out, including watering once every 5 days, manual weeding once a month, and no other insect repellent is applied to avoid interfering with the test results. Twenty citrus psylla traps are evenly distributed in the test plot, and the number of psyllids in the traps is counted every 15 days to calculate the insect density around the planting holes. On the 90th day of the test, the root damage rate, new shoot growth index, and leaf chlorophyll content of the plants are measured, and the infection of the Huanglongbing pathogen is also detected.

[0103] Table 4 Effect of different insect-proof isolation layer formulations on citrus planting hole insect control and plant growth

[0104]

[0105] As can be seen from the data in Table 4, the insect prevention effect and plant index of the blank control group (group 1) are the worst, the density of wood lice around the planting hole is as high as 10.5 per m2, the root damage rate is 28.6%, the pathogen infection rate is 22.5%, and the number of new shoots is only 3.5 per plant, which is completely consistent with the current situation that "no special insect prevention measures are arranged in the planting hole, and the medium insects are easy to invade and feed on the roots, leading to the spread of the pathogen", highlighting the core defect of the prior art in the planting link - only relying on later field insect prevention, unable to block the path of medium insects invading from the roots, and laying early hidden dangers for Huanglongbing infection.

[0106] The test groups (groups 2-6) are better than the control group, and group 4 performs best, and the specific data comparison and analysis are as follows: in terms of insect prevention effect index, the density of wood lice around the planting hole of group 4 is 2.3 per m2, which is reduced by 77.1% compared with group 1, 68.1% compared with group 2, and 73.3% compared with group 6; the root damage rate is 5.8%, which is reduced by 79.7% compared with group 1 and 37.0% compared with group 5; the pathogen infection rate is 3.5%, which is reduced by 84.4% compared with group 1 and 65.7% compared with group 3. This result shows that the azadirachtin-chitosan microsphere insect repellent with a ratio of 3:10 can achieve efficient insect prevention through double action: chitosan microspheres have good sustained-release performance, which can make azadirachtin continuously release within 90 days and maintain a stable insect repellent concentration; azadirachtin as a plant source insect repellent has strong antifeeding and oviposition inhibition effect on wood lice, and the insect prevention fiber film can physically block wood lice from entering the hole to contact the roots, solving the problem of the prior art that "insect prevention measures have short duration and limited physical blocking effect".

[0107] In terms of plant growth index, the number of new shoots of group 4 is 6.8 per plant, which is increased by 94.3% compared with group 1, 33.3% compared with group 3, and 15.3% compared with group 5; the average diameter of new shoots is 3.3 mm, which is increased by 57.1% compared with group 1 and 37.5% compared with group 2; the leaf SPAD value is 42.6, which is increased by 35.2% compared with group 1 and 30.0% compared with group 6. This is because the high-efficiency insect prevention effect of group 4 reduces the feeding damage of wood lice to the roots, ensures the normal nutrient absorption of the roots, and avoids the interference of pathogen infection on plant physiological metabolism, so that the photosynthetic efficiency and new shoot growth are significantly improved, which is in sharp contrast with the prior art that "single physical blocking (group 6) can only slightly reduce the insect density, and the roots are still damaged, and the plant growth is limited", and reflects the creativity of the present application.

[0108] Further analysis of the differences of groups 2, 3 and 5: group 2 has low insecticide ratio and insufficient load, poor slow-release effect, and the psyllid density still reaches 7.2 per m2, and the root damage rate is 19.3%; group 3 improves the ratio and load, but the pyrethrin is more volatile than azadirachtin, and the effective period is short, so the insect density rises in the later stage of the test, and the pathogen infection rate is 10.2%; group 5 uses starch-based microspheres as the carrier, and its slow-release performance is weaker than that of chitosan microspheres, resulting in a decline in the later insect prevention effect, and the root damage rate is 9.2%, which is 58.6% higher than that of group 4. These data differences fully prove that the "azadirachtin-chitosan microsphere ratio of 3:10 and load of 15 g / m2" defined in the application is not randomly set, but through the precise matching of the activity of the insecticide, the slow-release performance of the carrier and the load, long-term and efficient insect prevention is achieved, and the blank of "no clear insect prevention isolation layer formula and poor insect prevention effect during the planting period" in the prior art is filled, which provides key technical support for the prevention and control of citrus Huanglongbing disease during the planting stage.

[0109] Example 6

[0110] The sixth embodiment of the application also includes test preparation and implementation process:

[0111] The test was carried out in a subtropical citrus planting test base. The soil type of the base is red soil, and there are problems such as low organic matter content, poor water and fertilizer retention capacity, and strong acidity, which meets the typical scene of "insufficient soil fertility after planting, affecting plant growth and disease resistance" in the prior art. The test period is set to 100 days, and the test material is selected to be one-year-old Rabu citrus seedlings, a total of 240, which are randomly divided into 6 groups, 40 in each group. Group 1 is the blank control group (only untreated cultivated soil), and groups 2-6 are test groups (adopt different ratios of cultivated soil-biochar mixed substrates).

[0112] Test material preparation: the mixed substrate is composed of microwave-disinfected cultivated soil and self-made biochar. The cultivated soil is taken from the 0-30 cm cultivated layer of the test base, and after screening to remove impurities, it is disinfected for 20 minutes using a microwave disinfection device to kill potential pathogens in the soil; the biochar is made of citrus pruning waste branches and wood waste as raw materials, and the preparation process is as follows: the raw materials are crushed to a particle size of 2-5 cm, placed in a sealed carbonization furnace, carbonized at 500°C under anaerobic conditions for 3 hours, crushed to a particle size of 0.5-1 mm after cooling, then soaked in a 5%-10% phosphoric acid solution for 12 hours, and then dried at 110°C to constant weight to obtain activated biochar. According to the design formula "biochar mass fraction 5%-15%, biochar made from citrus branches or wood waste by high-temperature carbonization and activation", the specific grouping is as follows:

[0113] Group 1: blank control (only microwave-disinfected cultivated soil without biochar);

[0114] Group 2: microwave-disinfected cultivated soil + 5% unactivated biochar (biochar without phosphoric acid activation);

[0115] Group 3: Microwave sterilized cultivated soil + 5% activated biochar (activated with 5% phosphoric acid concentration);

[0116] Group 4: Microwave sterilized cultivated soil + 10% activated biochar (activated with 8% phosphoric acid concentration);

[0117] Group 5: Microwave sterilized cultivated soil + 15% activated biochar (activated with 8% phosphoric acid concentration);

[0118] Group 6: Microwave sterilized cultivated soil + 10% activated biochar (activated with 12% phosphoric acid concentration).

[0119] Preparation of mixed substrates and planting: Each group of mixed substrates was prepared with a dosage of 20 kg per plant. For example, for group 4, 18 kg of microwave sterilized cultivated soil and 2 kg of activated biochar were weighed, and deionized water was added to adjust the water content of the substrate to 25%. An electric mixer was used to stir for 15 minutes to ensure uniform mixing of the biochar and cultivated soil, and the mixture was ready for use. The test plot was excavated and planted with 40 holes, corresponding to 40 plants per group. Each planting hole was filled with the corresponding mixed substrate to a depth of 2 / 3, and the seedlings were planted with a rake. The remaining mixed substrate was backfilled in layers and gently compacted to ensure that the root system was in close contact with the substrate. After planting, each plant was irrigated with 6 L of rooting water containing amino acids and rooting promoters.

[0120] Post-planting management and monitoring: After planting, uniform field management was carried out, including watering once every 6 days and manual weeding once a month. No other fertilizers or fungicides were applied to avoid interfering with the test results. During the test period, substrate samples were collected every 20 days to measure pH, organic matter content, and available nutrient (nitrogen, phosphorus, and potassium) content. On the 100th day of the test, plant root morphological indicators (total root length, root surface area, and root hair number) and aboveground growth indicators (plant height increment, stem diameter increment, and leaf number) were measured. Meanwhile, 15 seedlings from each group were artificially inoculated with the Huanglongbing pathogen, and the incidence rate was recorded 30 days after inoculation.

[0121] Table 5 Effect of different cultivated soil-biochar mixed substrate formulations on citrus growth and disease resistance

[0122]

[0123] From the data in Table 5, the matrix quality and plant indicators of the blank control group (group 1) are the worst, the matrix pH value is only 5.2, the organic matter is 1.1%, the available potassium is 85 mg / kg, the total root length is 52.3 cm / plant, the incidence rate after artificial inoculation is 35.2%, which is completely consistent with the current situation that "only using conventional cultivated soil for planting, the soil is strongly acidic and low in fertility, which cannot meet the growth and disease resistance needs of plants", highlighting the core defect of the prior art in the soil matrix improvement link - lack of targeted matrix optimization measures, leading to limited root growth, poor plant stress resistance, and easy infection by Huanglongbing pathogen.

[0124] The test groups (groups 2-6) are better than the control group, and group 4 performs best, with specific data comparison and analysis as follows: in terms of matrix indicators, the matrix pH value of group 4 is 6.3, which is increased by 21.2% compared with group 1 and by 14.5% compared with group 2; the organic matter content is 2.4%, which is increased by 118.2% compared with group 1 and by 33.3% compared with group 3; the available potassium content is 185 mg / kg, which is increased by 117.6% compared with group 1 and by 3.9% compared with group 6. This result shows that 10% activated biochar can improve the matrix quality through multiple effects: the alkaline nature of biochar can neutralize the acidity of red soil and adjust the pH value to the suitable growth range of citrus; its high specific surface area and pore structure can adsorb and store nutrients, increasing the content of available nutrients; the phosphoric acid activation process can further increase the number of functional groups on the surface of biochar, enhancing the adsorption and fertilizer retention capacity, and solving the problem of "strong soil acidity and easy loss of fertility" in the prior art.

[0125] In terms of plant growth and disease resistance indicators, the total root length of group 4 is 98.6 cm / plant, which is increased by 88.5% compared with group 1 and decreased by 6.4% compared with group 5; the plant height increment is 29.8 cm, which is increased by 120.7% compared with group 1 and by 31.9% compared with group 3; the incidence rate after artificial inoculation is 11.5%, which is decreased by 67.3% compared with group 1, by 59.8% compared with group 2, and by 36.8% compared with group 6. This is because the optimized matrix of group 4 provides a suitable pH environment and sufficient nutrients for the root system, promoting root growth and thus improving plant nutrient uptake capacity and photosynthetic efficiency, while the carbonaceous components in biochar can stimulate the plant to produce a stress response, enhance the activity of disease resistance-related enzymes, and reduce the probability of pathogen infection, which is in sharp contrast to the prior art "unactivated biochar can only slightly improve the matrix, and the plant growth and disease resistance are limited", demonstrating the creativity of the present application.

[0126] Further analysis of the differences between groups 2, 3, 5, 6: group 2 is not activated by biochar, the surface pore and the number of functional groups are small, the substrate improvement effect is weak, the available potassium is only 112 mg / kg, and the total root length is 68.5 cm / plant; group 3 is insufficient in biochar dosage, although it can improve the substrate, but the nutrient supply is limited, the increment of plant height is 22.6 cm, which is 24.2% lower than that of group 4; group 5 is excessive in biochar, which leads to excessive porosity of the substrate, and the water retention capacity decreases, the root system is easy to be stressed by drought, and the incidence rate is 15.8%, which is 37.4% higher than that of group 4; group 6 uses 12% high-concentration phosphoric acid for activation, and excessive activation leads to excessive acid functional groups on the surface of biochar, which reduces the pH value of the substrate, and destroys the pore structure of biochar, the available potassium is 178 mg / kg, which is 3.8% lower than that of group 4, and the incidence rate is 18.2%, which is 58.3% higher than that of group 4. These data differences fully prove that the “10% biochar mass fraction, 8% phosphoric acid activation” defined in the present application is not randomly set, but through the precise matching of biochar dosage and activation degree, the optimal balance between the physical and chemical properties of the substrate and the plant demand is realized, and the blank of “unclear tillage soil-biochar ratio and activation process, unstable substrate improvement effect” in the prior art is filled, and a scientific and efficient technical scheme for optimizing the soil environment after citrus planting is provided.

[0127] Example 7

[0128] The seventh embodiment of the present application also includes test preparation and implementation process:

[0129] The test is carried out in an adult citrus orchard in the main citrus producing area in the south, and 5-year-old sugar orange trees are planted in the orchard. The incidence rate of huanglongbing disease is about 15%-20% every year, which meets the typical scene of “only conventional fertilization during the growth period, weak plant disease resistance, and easy to be infected by huanglongbing disease” in the prior art. The test cycle is set to 6 months, 240 sugar orange trees with consistent tree vigor and no pests and diseases are selected, and they are randomly divided into 6 groups, 40 trees in each group, group 1 is a blank control group (only spraying water), and groups 2-6 are test groups (spraying different ratios of disease-resistant nutrient agents).

[0130] Test material preparation: the disease-resistant nutrient agent is composed of plant source disease-resistant inducer, trace element foliar fertilizer and additive. The plant source disease-resistant inducer selects salicylic acid (purity ≥ 99%), methyl jasmonate (purity ≥ 98%) and chitosan oligosaccharide (molecular weight 5000 Da, purity ≥ 95%); the trace element foliar fertilizer is a mixed solution of chelated calcium, magnesium and boron; and the additive is a non-ionic surfactant. According to the defined “at least one of salicylic acid, methyl jasmonate or chitosan oligosaccharide is used as the plant source disease-resistant inducer, the non-ionic surfactant is used as the additive, and the mass ratio of the plant source disease-resistant inducer, the trace element foliar fertilizer and the additive is (1-2):(5-8):(0.5-1)”, the formula is designed as follows:

[0131] Group 1: blank control (spraying water, no nutrient agent composition);

[0132] Group 2: salicylic acid + trace element foliar fertilizer + adjuvant (mass ratio 1:5:0.5);

[0133] Group 3: methyl jasmonate + trace element foliar fertilizer + adjuvant (mass ratio 1:8:0.8);

[0134] Group 4: chitosan oligosaccharide + trace element foliar fertilizer + adjuvant (mass ratio 2:6:1);

[0135] Group 5: salicylic acid + methyl jasmonate (1:1 mixture) + trace element foliar fertilizer + adjuvant (mass ratio 1.5:6:0.8);

[0136] Group 6: chitosan oligosaccharide + trace element foliar fertilizer (no adjuvant, mass ratio 2:6).

[0137] Preparation and spraying of disease-resistant nutrient agents: Each group of nutrient agents was prepared as a 1000-fold dilution liquid. For example, for Group 4, 200 g of chitosan oligosaccharide, 600 g of trace element foliar fertilizer, and 100 g of non-ionic surfactant were mixed, and then deionized water was added to make up to 100 kg to prepare the mother liquor. When spraying, 100 g of the mother liquor was added to 99.9 kg of water and stirred uniformly to obtain a 1000-fold dilution liquid. A backpack electric sprayer was used for spraying to ensure that the droplets uniformly covered the front and back of the leaves and the new shoots. The spraying amount was 500 mL per plant per time, and the spraying period was once every 15 days, for a total of 12 times.

[0138] Growth period management and monitoring: During the test period, unified orchard management was carried out, including watering once every 7 days, manual weeding, and routine pruning. No other fungicides or disease-resistant agents were used to avoid interfering with the test results. Leaf samples were collected from each group of plants every 30 days to measure photosynthetic parameters and disease-resistant enzyme activity. After the test was completed, the number of new shoots and the new shoot damage rate were counted, and the PCR technique was used to detect the infection rate of Huanglongbing pathogen in each group of plants, and the incidence rate was calculated.

[0139] Table 6 Effect of different disease-resistant nutrient agent formulations on the growth and disease resistance of citrus during the growth period

[0140]

[0141] From the data in Table 6, the indicators of the blank control group (group 1) are the worst, the net photosynthetic rate of the leaves is only 6.8 μmol / (m²·s), the POD activity is 92.5 U / (g·min), the new shoot damage rate is 28.5%, and the Huanglongbing disease incidence is 18.6%, which is completely consistent with the current situation in the prior art that "only spraying water during the growth period, lacking disease resistance induction and nutrient supplementation, weak photosynthetic capacity of the plant, low disease resistance enzyme activity, and easy to be infected by the pathogenic bacteria", highlighting the core defect of the prior art in the growth period prevention and control link - only relying on environmental management, unable to enhance the disease resistance of the plant from the physiological level, leading to the new shoots being easily damaged and the high incidence of Huanglongbing disease.

[0142] The test groups (groups 2-6) are better than the control group, and group 4 performs best, and the specific data comparison and analysis are as follows: in terms of photosynthesis and enzyme activity indicators, the net photosynthetic rate of the leaves of group 4 is 11.5 μmol / (m²·s), which is increased by 69.1% and 35.3% compared with group 1, and increased by 20.0% compared with group 6; the POD activity is 186.7 U / (g·min), which is increased by 101.8% compared with group 1, and increased by 28.5% compared with group 3; the PPO activity is 105.8 U / (g·min), which is increased by 81.5% compared with group 1, and increased by 7.3% compared with group 5. This result shows that the disease-resistant nutrient agent with a 2:6:1 ratio can enhance the physiological function of the plant through multiple effects: chitosan as a disease resistance inducer can activate the immune system of the plant and promote the synthesis of disease resistance enzymes (POD, PPO) - POD can remove active oxygen generated by the invasion of pathogenic bacteria, and PPO can catalyze the oxidation of phenolic substances to form antibacterial substances; trace element foliar fertilizer supplements the nutrients required for plant growth, magnesium is the core component of chlorophyll, which can increase the photosynthetic rate; and non-ionic additives can reduce leaf surface tension, increase the adhesion and absorption efficiency of the nutrient agent, solving the problem of "poor absorption of the nutrient agent and weak disease resistance induction effect" in the prior art.

[0143] In terms of growth and disease resistance indicators, the number of new shoots of group 4 is 58 per plant, which is increased by 81.3% compared with group 1, and increased by 28.9% compared with group 3; the new shoot damage rate is 8.3%, which is reduced by 70.9% compared with group 1, and reduced by 21.0% compared with group 5; and the Huanglongbing disease incidence is 4.2%, which is reduced by 77.4% compared with group 1, and reduced by 62.8% compared with group 6. This is because the optimized formula of group 4 not only induces the plant to produce systemic resistance through chitosan to reduce pathogenic bacterial infection, but also increases the photosynthetic efficiency through trace elements to provide sufficient energy for the growth of new shoots, and at the same time, the additives ensure efficient absorption of the nutrient agent, forming a synergistic effect of "inducing disease resistance-nutrient strengthening-optimizing absorption", which is in sharp contrast to the prior art "non-additive group (group 6) with low absorption efficiency, POD activity of only 135.2 U / (g·min), and disease incidence of 11.3%", reflecting the inventiveness of the present application.

[0144] Further analysis of the differences of groups 2, 3, 5, 6: group 2 is low in the amount of disease resistance inducer, and the salicylic acid induction effect is weaker than chitosan oligosaccharide, the POD activity is only 128.6 U / (g min), and the new shoot damage rate is 19.2%; group 3 increases the ratio of methyl jasmonate and foliar fertilizer, but methyl jasmonate easily leads to slight early senescence of leaves, and the net photosynthetic rate is 20.0% lower than that of group 4; group 5 uses mixed inducers, which can increase enzyme activity, but the two kinds of inducers compete in the signal pathway, resulting in a disease resistance effect lower than that of single chitosan oligosaccharide; group 6 has no auxiliary agent, and the nutrient agent forms droplets on the leaves and is lost, the absorption efficiency is low, the PPO activity is 78.5 U / (g min), which is 25.8% lower than that of group 4, and the incidence rate is 11.3%, which is 169.0% higher than that of group 4. These data differences fully prove that the "chitosan oligosaccharide as an inducer, mass ratio 2:6:1, and addition of a non-ionic auxiliary agent" defined in the application is not randomly set, but through component selection, ratio optimization and auxiliary agent adaptation, the disease resistance effect is maximized, filling the gap in the prior art that "the composition and proportion of disease resistance nutrients are not clear, and the effect of growth period prevention and control is unstable", and providing an efficient and precise technical solution for the prevention and control of citrus Huanglongbing disease in the growth period.

[0145] Example 8

[0146] Reference will now be made to Figure 2 , which shows a structural diagram of an electronic device suitable for implementing some embodiments of the present application. The electronic device in some embodiments of the present application can include, but is not limited to, mobile terminals such as mobile phones, notebook computers, digital broadcast receivers, PDAs (Personal Digital Assistants), PADs (Tablet PCs), PMPs (Portable Multimedia Players), vehicle terminals (e.g., car navigation terminals), and the like, as well as fixed terminals such as digital TVs, desktop computers, and the like. Figure 2 The terminal device shown is merely an example and should not impose any limitation on the function and use range of the embodiments of the present application.

[0147] As shown in Figure 2 , the electronic device used can include a processing device (e.g., a central processor, a graphic processor, etc.) 301, which can perform various appropriate actions and processes according to programs stored in a read-only memory (ROM) 302 or loaded from a storage device 308 into a random access memory (RAM) 303. In the RAM 303, various programs and data required for the operation of the electronic device are also stored. The processing device 301, the ROM 302, and the RAM 303 are connected to each other through a bus 304. An input / output (I / O) interface 305 is also connected to the bus 304.

[0148] Generally, the following devices can be connected to the I / O interface 305: input devices 306 including, for example, a touch screen, a touch pad, a keyboard, a mouse, a camera, a microphone, an accelerometer, a gyroscope, and the like; output devices 307 including, for example, a liquid crystal display (LCD), a speaker, a vibrator, and the like; storage devices 308 including, for example, a magnetic tape, a hard disk, and the like; and communication devices 309. The communication devices 309 can allow the electronic device to communicate wirelessly or wiredly with other devices to exchange data. Although Figure 2 Electronic devices having various devices are shown, but it is understood that all of the shown devices are not required to be implemented or present. More or less devices can alternatively be implemented or present. Figure 2 Each block shown in the flowcharts of FIGS. 10 and 11 can represent a device or multiple devices as necessary.

[0149] Further, the storage medium of the embodiments of the present application stores program instructions capable of implementing all the methods described above, wherein the program instructions can be stored in the storage medium in the form of a software product, including a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor execute all or part of the steps of the methods described in the embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various media capable of storing program codes, or a computer, a server, a mobile phone, a tablet, and the like.

Claims

1. A citrus planting method for reducing Huanglongbing, characterized by, The following procedure is implemented: The seedlings detected without HLB pathogen are pre-treated by gradient soaking the root system and branch surface with the treatment solution of osmotic regulator and chelated trace elements in a predetermined ratio; then the pre-treated seedlings are placed in a sterile environment and cultivated in a substrate containing humic acid and probiotic bacteria until the new shoots germinate and grow healthily; After deep ploughing the land, a composite amendment composed of mature organic fertilizer, mineral source bacteriostatic agent and soil structure modifier is applied and covered with film; The planting hole is dug according to the predetermined plant spacing, and the isolation layer composed of insect-proof fiber membrane and slow-release insect repellent is laid at the bottom of the hole; The treated seedlings are planted and backfilled with the mixed substrate of microwave-sterilized cultivated soil and biochar, and then the root-fixing nutrient solution containing amino acid and root-promoting agent is poured after planting; The diseased residues and weeds are regularly checked and removed, and the disease-resistant nutrient agent containing plant-derived disease-resistant inducer, trace element foliar fertilizer and auxiliary agent is sprayed every predetermined period; The trapping device containing sex pheromone and contact-killing agent is laid, and the operation tools are soaked in the solution containing quaternary ammonium salt disinfectant before field operation; After fruit picking, the branches with potential pathogens are pruned, the protective solution containing broad-spectrum antibacterial agent and plant growth regulator is sprayed, the land is ploughed again, and the soil repair agent containing organic fertilizer and microbial agent is supplemented; The osmotic regulator is at least one of polyethylene glycol, propylene glycol or glycerol, and the chelated trace elements are a mixture of chelated iron, chelated zinc and chelated manganese in a mass ratio of (1-3):(1-2):

1. In the isolation layer, the slow-release insect repellent is a mixture of pyrethrin or azadirachtin and a slow-release carrier in a mass ratio of (1-3):(10-20), the slow-release carrier is starch-based microspheres or chitosan microspheres, and the insect-proof fiber membrane is polyester fiber membrane pretreated with insect repellent.

2. The citrus planting method for reducing Huanglongbing according to claim 1, wherein, The mass fraction of humic acid in the humic acid and probiotic group-containing substrate is 5%-15%, the probiotic group is a complex bacterial group composed of Bacillus subtilis and jelly-like Paenibacillus according to the colony number ratio (2-3):1, and the effective viable bacterial number of the probiotic group in the substrate is not less than 1×10 8 CFU / g.

3. The citrus planting method for reducing Huanglongbing according to claim 1, wherein, In the composite amendment, the mass ratio of mature organic fertilizer, mineral source bacteriostatic agent and soil structure modifier is (8-12):(1-2):(0.5-1), the mineral source bacteriostatic agent is montmorillonite or zeolite powder loaded with antibacterial components, and the soil structure modifier is vermiculite or perlite.

4. The citrus planting method for reducing Huanglongbing according to claim 1, wherein, In the mixed substrate of cultivated soil and biochar, the mass fraction of biochar is 5%-15%, and the biochar is made of citrus branches or wood waste by high-temperature carbonization and activation, and a phosphoric acid solution with a mass fraction of 5%-10% is used for activation treatment during the activation process.

5. The citrus planting method for reducing Huanglongbing according to claim 1, wherein, In the disease-resistant nutrient agent, the plant-derived disease-resistant inducer is at least one of salicylic acid, methyl jasmonate or chitosan oligosaccharide, the auxiliary agent is a non-ionic surfactant, and the mass ratio of plant-derived disease-resistant inducer, trace element foliar fertilizer and auxiliary agent is (1-2):(5-8):(0.5-1).

6. The citrus planting method for reducing Huanglongbing according to claim 5, wherein, In the protective solution, the broad-spectrum antibacterial agent is kasugamycin or zinc thiazole, the plant growth regulator is brassinolide or gibberellin, and the mass ratio of broad-spectrum antibacterial agent and plant growth regulator is (5-10):(1-2); in the soil repair agent, the mass ratio of organic fertilizer and microbial agent is (10-15):(1-2), and the microbial agent is a composite microbial agent of nitrogen-fixing bacteria and phosphorus-dissolving bacteria.

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