Microbial agent for promoting cucumber growth and preparation method and application thereof

Abstract

The invention discloses a microbial agent for promoting cucumber growth and a preparation method and application thereof, and belongs to the technical field of agricultural microorganisms. The microbial agent is prepared from the following components: achromobacter denitrificans, bradyrhizobium angularis and Vilnelandan nitrogen-fixing bacteria in a volume ratio of 2 to 1 to 1. Bacteria with a growth promoting effect are reasonably combined for use, so that the growth promoting effect of the mixed flora on cucumbers is better than that of a single strain, and the adaptability of the synergistic effect of the strains in the actual soil rhizosphere complex environment is higher. By determining the number of strains and mixing according to a specific proportion, germination of cucumber seeds is stably and effectively promoted, root elongation is promoted, the flowering and fruit setting rate is increased, and meanwhile the plant height, plant biomass and chlorophyll content of cucumbers in the seedling stage are increased. Besides, the microbial agent disclosed by the invention is beneficial to improving the growth quality and yield of plants and reducing environmental pollution, has wide application potential in the fields of agriculture and ecology, and is worthy of popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of agricultural microorganisms, and particularly relates to a microbial agent for promoting cucumber growth and a preparation method and application thereof. Background Art

[0002] Long-term application of chemical fertilizers will increase the salt concentration in the soil, leading to soil compaction, acid-base imbalance and other problems, which will affect the growth and development of cucumbers at the least and cause secondary salinization of the soil at the worst. Similarly, improper fertilization will destroy the soil structure, resulting in poor soil permeability and water retention, affecting the normal growth of cucumbers. Therefore, the lack of standardized fertilization guidance will lead to low crop yields and many deformed fruits, affecting the cultivation benefits. At present, with the deepening of research on microbial agents, people have found that the use of agents prepared by microorganisms in agricultural production can promote plant growth, which has very important practical significance for the growth regulation of cucumber plants and provides new ideas for the ecological cultivation of cucumbers.

[0003] For example, Chinese patent CN113249243A discloses a strain of Pseudomonas, a microbial biocontrol agent containing the strain and its application, discloses a microbial biocontrol agent containing the Pseudomonas and its preparation method, and the application of ZL8 and its biocontrol agent in inhibiting plant pathogenic fungi and promoting plant growth. The provided biocontrol strain ZL8 has a strong inhibitory effect on cucumber brown spot fungus, rapeseed sclerotinia, wheat fusarium, potato wilt or Salvia miltiorrhiza pathogenic fungi, and has good disease prevention and control effects and growth promotion and yield increase effects in cucumber and Panax notoginseng plants.

[0004] For another example, Chinese patent CN116286550A discloses a multifunctional Pusha rhizobium, a microbial agent containing it, and its application. The Pusha rhizobium strain was isolated from the rhizosphere soil of cucumbers where root-knot nematodes were infected. The fermentation supernatant of the strain has a strong contact killing ability to root-knot nematodes and has the functions of salt tolerance, dissolving insoluble inorganic phosphorus and secreting auxin. The strain can not only significantly promote the growth of cucumber seedlings, but also retard the development process of root-knot nematodes in the cucumber root system, significantly reduce the number of root knots and egg masses per unit of the cucumber root system, and is conducive to the early prevention and control of root-knot nematodes. However, the complexity and variability of the current agricultural production environment make it impossible for single-function microbial agents to fully exert their expected growth-promoting effects in actual applications.

[0005] Therefore, the development of mixed inoculants of multiple microbial strains is of great significance for improving agricultural production efficiency and quality. Inoculants prepared from multiple microbial strains can be more adaptable in the complex environment of the actual soil rhizosphere, thereby effectively promoting the growth and high yield of crops. Summary of the invention

[0006] The present invention provides a microbial agent for promoting cucumber growth, a preparation method and an application thereof. A plurality of microbial strains are rationally compounded to obtain a microbial agent which stably and effectively promotes cucumber seed germination, promotes root elongation, improves flowering and fruit setting rate and increases single plant yield, and simultaneously improves plant height, plant biomass and chlorophyll content in the cucumber seedling stage. Therefore, the microbial agent of the present invention can have a growth-promoting effect on cucumber seeds and seedlings throughout the entire growth period.

[0007] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0008] A microbial agent for promoting cucumber growth, comprising the following components: Achromobacter denitrificans, Bradyrhizobium elkanii, and Azotobacter vinelandii, in a volume ratio of 2:1:1;

[0009] The denitrifying Achromobacter was purchased from the General Microbiological Center of China Microbiological Culture Collection Administration (CGMCC), with the strain number of CGMCC No.1.2684; the original preservation time was July 11, 2000;

[0010] The Bradyrhizobium elsdenii was purchased from the General Microbiological Center of China Microorganism Culture Collection Administration (CGMCC), with the strain number of CGMCC No.1.15559; the original preservation time was December 30, 2015;

[0011] The Vinelandia nitrogen-fixing bacteria were purchased from the General Microbiology Center of China Microorganism Culture Collection Administration (CGMCC), with the strain number of CGMCC No.1.7741; the original preservation time was July 24, 2008.

[0012] The three microbial strains used in the present invention can be purchased through the strain catalog of the General Microbiological Center of the China Microbiological Culture Collection Administration, without the need for repeated biological preservation.

[0013] Furthermore, the viable bacteria count of the denitrifying Achromobacter is 1×10 7 cfu / mL; the viable bacterial count of Bradyrhizobium elsdenii is 1×10 7 cfu / mL; the viable bacterial count of the Vineland nitrogen-fixing bacteria is 1×10 7 cfu / mL.

[0014] Furthermore, the microbial agent is a liquid agent.

[0015] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0016] (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0017] (2) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution;

[0018] (3) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0019] (4) The three bacterial solutions were mixed in a volume ratio of 2:1:1 to obtain the final product microbial agent.

[0020] Furthermore, the method for preparing the fermentation medium of Achromobacter denitrifyingensis is as follows: 10 g / L peptone, 3 g / L beef extract powder, 5 g NaCl, 15 g agar, add distilled water to 1 liter, and the pH is 7.

[0021] Further, the preparation method of the fermentation medium of Bradyrhizobium elsdenii and Azotobacter vinelanderi is as follows: 20 g of mannitol, 15 g of agar, 0.5 g of yeast extract, KH 2 PO 4 0.2g, K 2 HPO 4 0.8 g MgSO 4 7H 2 O 0.2g, CaSO 4 ·2H 2 O0.1g, FeCl 3 0.1g, Na 2 MoO 4 ·2H 2 O 0.1g, add distilled water to 1 liter, pH 7.

[0022] Furthermore, the microbial agent is used to promote the growth of cucumbers.

[0023] Furthermore, the microbial agent is used in promoting seed germination, promoting root elongation, increasing flowering and fruiting rate, increasing single plant yield, plant height of cucumber seedlings, plant biomass and chlorophyll content.

[0024] Furthermore, the application method of the microbial agent is seed soaking and root application.

[0025] The microbial agent of the present application can be used for root irrigation during the plant growth stage or seedling stage. The prepared microbial agent is diluted 100 times, 100 ml is used for each plant, and applied once every two weeks, and the application period includes the cucumber seedling stage, flowering stage and / or fruiting stage.

[0026] The present invention introduces denitrifying Achromobacter, which can effectively promote the growth of crops and show stronger adaptability in complex soil environments. They participate in the nitrogen cycle in the soil, optimize the conversion of nitrogen, improve the absorption and utilization efficiency of nitrogen by plants, and increase crop yields.

[0027] Secondly, the introduction of Bradyrhizobium elsdenii can promote growth by producing plant hormones and improving plant nutrient absorption. In addition, Bradyrhizobium elsdenii can indirectly improve plant growth by inducing systemic resistance in host plants. It can also increase the adhesion of roots to the soil by releasing extracellular polysaccharides, thereby regulating the movement of water and soil nutrients.

[0028] In addition, the introduction of Vinelandia nitrogen-fixing bacteria can secrete a variety of plant growth regulating hormones, such as auxin (IAA), gibberellin (GA) and cytokinin (CTK), thereby promoting plant growth and development. These hormones not only help to increase the respiration rate and metabolism of plant roots, but also stimulate the formation of root hairs, thereby enhancing the plant's ability to absorb minerals. In addition, Vinelandia nitrogen-fixing bacteria convert nitrogen in the air into ammonia nitrogen that can be used by plants through its nitrogen fixation, providing plants with essential nitrogen nutrition. This nitrogen fixation process not only increases the nitrogen content in the soil, but also reduces the use of chemical fertilizers, thereby reducing environmental pollution.

[0029] Beneficial Effects

[0030] The mixed bacterial community of the present invention has a better effect on promoting the growth of cucumber than a single strain, and the synergistic effect between bacterial species is more adaptable in the complex environment of the actual soil rhizosphere. By determining the number of strains and the mixing of a specific ratio, the cucumber seed germination, root elongation, flowering and fruiting rate, and single plant yield can be stably and effectively promoted, while the plant height, plant biomass, and chlorophyll content of the cucumber seedling stage can be increased. In addition, the bacterial combination is better than the fungal combination. The bacterial culture time is short, and the bacterial culture efficiency is better than that of fungi. And bacteria are more tolerant to complex and harsh environments than fungi.

[0031] The microbial agent of the present invention helps to improve the growth quality and yield of plants while reducing environmental pollution, has broad application potential in the fields of agriculture and ecology, and is worthy of promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 This is a diagram of the growth status of different strains in LB medium. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is further described below in conjunction with specific embodiments, but is not limited thereto.

[0034] Example 1

[0035] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0036] (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0037] (2) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution;

[0038] (3) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0039] (4) The three bacterial solutions were mixed in a volume ratio of 2:1:1 to obtain the final product microbial agent.

[0040] Verification of strain antagonism:

[0041] The frozen Achromobacter denitrifyingus, Bradyrhizobium elsdenii and Azotobacter vinelandii were activated, streaked on LB medium plates and cultured at 25-30°C for 3-5 days.

[0042] The three bacteria were streaked onto one culture medium, with the horizontal line representing Achromobacter denitrificans, the vertical line representing Bradyrhizobium elsdenii, and the diagonal line representing Azotobacter veneri, to fully demonstrate that there was no mutual inhibition between the strains. Figure 1 As shown, there is no obvious inhibition zone between the three bacteria, indicating that there is no obvious inhibitory effect between them, and the composite bacterial solution can be compounded.

[0043] Comparative Example 1

[0044] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0045] (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0046] (2) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution;

[0047] (3) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0048] (4) The three bacterial solutions were mixed in a volume ratio of 1:2:1 to obtain the final product microbial agent.

[0049] Comparative Example 2

[0050] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0051] (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0052] (2) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution;

[0053] (3) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0054] (4) The three bacterial solutions were mixed in a volume ratio of 1:1:2 to obtain the final product microbial agent.

[0055] Comparative Example 3

[0056] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0057] (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0058] (2) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution;

[0059] (3) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0060] (4) The three bacterial solutions were mixed in a volume ratio of 1:1:1 to obtain the final product microbial agent.

[0061] Comparative Example 4

[0062] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0063] (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0064] (2) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution;

[0065] (3) The two bacterial solutions were mixed in a volume ratio of 2:1 to obtain the final product, a microbial agent.

[0066] Except that no nitrogen-fixing bacteria Vinelandia was added in this comparative example, the other raw materials and steps were the same as those in Example 1.

[0067] Comparative Example 5

[0068] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0069] (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0070] (2) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0071] (3) The two bacterial solutions were mixed in a volume ratio of 2:1 to obtain the final product, a microbial agent.

[0072] In this comparative example, except that Bradyrhizobium elsdenii was not added, the remaining raw materials and steps were the same as those in Example 1.

[0073] Comparative Example 6

[0074] A method for preparing a microbial agent for promoting cucumber growth comprises the following preparation steps:

[0075] (1) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution;

[0076] (2) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution;

[0077] (3) The two bacterial solutions were mixed in a volume ratio of 1:1 to obtain the final product, a microbial agent.

[0078] In this comparative example, except that Achromobacter denitrificans was not added, the remaining raw materials and steps were the same as those in Example 1.

[0079] Performance Testing

[0080] Test 1: Seed germination rate determination

[0081] Select Zhongnong 116 cucumber seeds with full seeds and no damage, and set 120 seeds as a group, and set one group each of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6 and blank control, for a total of 8 groups.

[0082] Seed treatment: The cucumber seeds were soaked in 75% alcohol for 30 seconds for surface sterilization, rinsed once with sterile water, and then soaked in 6% sodium hypochlorite for 15 minutes, shaken from time to time during the period, and the sodium hypochlorite was poured out. After rinsing with sterile water for 6 times, the seeds were soaked in 50°C warm water for 1 hour, and the surface moisture of the seeds was absorbed with absorbent paper. Then, they were soaked in the solutions of the embodiment, comparative example and blank control for 10 hours, and then cultured in a culture dish.

[0083] Each treatment setting: Use the aqueous solution diluted 100 times with each group of microbial agents in the embodiment and comparative example, and soak each group of cucumber seeds with an equal amount of water in the blank control group. Each group of cucumber seeds is placed in a 100×100mm culture dish, and 2 layers of filter paper are added to the bottom of the culture dish. 40 seeds are evenly placed in each culture dish, and each treatment is repeated 3 times. After soaking in the solution of the embodiment, comparative example and blank control for 10 hours, 5mL of purified water is added to each culture dish, and 1mL of purified water is added every day. After being placed in a dark incubator at 25°C for 5 days, the number of germinations in each group is counted, and the germination rate is calculated in Table 1.

[0084] Germination rate (%) = (germinated seeds / test seeds) × 100%, and cucumber seeds are considered germinated when their white length is greater than or equal to 80%.

[0085] Table 1. Germination of cucumber seeds after 5 days of soaking in different solutions

[0086]

[0087] It can be seen from Table 1 that the seed germination rate using the microbial agent of Example 1 of the present invention is greatly improved.

[0088] Experiment 2: Root growth measurement

[0089] Select Zhongnong 116 cucumber seeds with full seeds and no damage, and set 60 seeds as a group, and set one group each of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6 and blank control, for a total of 8 groups.

[0090] Seed treatment: The cucumber seeds were soaked in 75% alcohol for 30 seconds for surface sterilization, rinsed once with sterile water, and then soaked in 6% sodium hypochlorite for 15 minutes, shaking from time to time during the period, and the sodium hypochlorite was poured out. After rinsing with sterile water for 6 times, the seeds were soaked in 50°C warm water for 1 hour, and the surface moisture of the seeds was absorbed with absorbent paper. Then, they were soaked in the solutions of the embodiment, comparative example and blank control for 10 hours, and then rinsed with distilled water and placed in a culture dish.

[0091] Each treatment setting: Use the aqueous solution diluted 100 times with each group of microbial agents in the embodiment and comparative example, and soak the cucumber seeds of each group in the blank control group and the same amount of water for 10 hours. After rinsing each group of cucumber seeds with distilled water, put the seeds in a 100×100mm culture dish, add 2 layers of filter paper to the bottom of the culture dish, and evenly place 20 seeds in each culture dish. Repeat each treatment 3 times. Add 5mL of purified water to each culture dish, add 1mL of purified water every day, and place it in a dark incubator at 25℃ for 5 days. Randomly take out 10 seedlings from each culture dish, and measure the taproot length and the number of primary lateral roots of each seedling in Table 2. The results of each experimental group are averaged.

[0092] Table 2 Root growth of cucumber seeds 5 days after soaking in different solutions

[0093] Group Taproot length / cm Number of primary lateral roots Blank control 3.25 2.9 Example 1 4.57 5.3 Comparative Example 1 3.46 3.7 Comparative Example 2 3.91 3.9 Comparative Example 3 3.64 4.5 Comparative Example 4 3.43 3.5 Comparative Example 5 3.41 3.5 Comparative Example 6 3.36 3.3

[0094] As can be seen from Table 2, the taproot length and the number of primary lateral roots of Example 1 are better than those of the blank control and each comparative example. The taproot length of Example 1 increased by 40.6% compared with the blank control, and the number of primary lateral roots increased by 76.7% compared with the blank control, which proves that Example 1 can significantly promote the taproot length and the number of primary lateral roots of cucumber seedlings.

[0095] Test 3

[0096] Select Zhongnong 116 cucumber seeds with full seeds and no damage, and set 30 seeds as a group, and set one group each of Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6 and blank control, for a total of 8 groups.

[0097] Seed treatment: Soak the cucumber seeds in 75% alcohol for 30 seconds for surface sterilization, rinse once with sterile water, and then soak in 6% sodium hypochlorite for 15 minutes. Shake occasionally during the period, pour out the sodium hypochlorite, rinse with sterile water 6 times, soak the seeds in 50℃ warm water for 1 hour, wash with distilled water, wipe dry and set aside.

[0098] Each treatment setting: Place the treated cucumber seeds of each group in a 100×100 mm culture dish, add 2 layers of filter paper to the bottom of the culture dish, evenly place 10 seeds in each culture dish, and repeat each treatment 3 times. Add 5 mL of purified water to each culture dish, add 1 mL of purified water every day, and place it in a 25°C incubator for dark culture for 5 days. Randomly take out 5 seedlings of the same growth in each group from each culture dish, inoculate each group of seedlings into a seedling box, and then take 100 ml of a 100-fold diluted aqueous solution of the microbial agent in each group of the embodiment and the comparative example, and irrigate the blank control group and water in each group of seedling boxes. When the cucumber seedlings of each group are 30 days old, the biomass of the plants is measured, and the growth promotion effect is shown in Table 3.

[0099] Table 3 Biomass of cucumber plants after root irrigation with different solutions

[0100] Group Plant height / cm Fresh weight of aboveground parts / g Aboveground dry weight / g Chlorophyll content mg / L Blank control 16.5 4.1 0.77 9.73 Example 1 21.3 8.1 1.42 20.12 Comparative Example 1 18.9 6.9 1.24 17.43 Comparative Example 2 19.4 7.3 1.29 17.81 Comparative Example 3 20.1 7.6 1.35 18.25 Comparative Example 4 17.6 5.4 0.98 13.69 Comparative Example 5 17.8 5.7 1.04 13.94 Comparative Example 6 16.9 5.1 0.95 11.28

[0101] As shown in Table 3, after 30 days of planting, the use of the microbial agent of Example 1 of the present invention increased the height, fresh weight of the aboveground part, dry weight of the aboveground part and chlorophyll of cucumber by 29.1%, 97.6%, 84.4% and 106.7% respectively compared with the blank control, indicating that the microbial agent of the present invention has a significant promoting effect on the growth of cucumber seedlings. In addition, compared with Example 1 of the present invention, after changing the ratio of bacterial species, the various indicators of the growth promotion of cucumber seedlings in the comparative example are lower than those in Example 1, indicating that the specific ratio of bacterial species in Example 1 of the present invention can play the greatest effect.

[0102] Determination of flowering, fruit setting and yield in Experiment 4

[0103] The cucumber seedlings of three leaves and one heart are selected for transplanting and planting in the greenhouse, and embodiment 1, comparative example 1, comparative example 2, comparative example 3, comparative example 4, comparative example 5, comparative example 6 and blank are set, a total of 8 groups. Each group selects 10 seedlings with the same and healthy growth to be planted, and a group of blank is set between each group to do protection row. After planting for one week, the microbial agent prepared by each group is diluted 100 times, and the blank is used for root irrigation treatment with equal amount of water, and each group is irrigated with 100ml, and continues to be irrigated once after two weeks. After planting for one and a half months, the flowering number of each group of individual plants is counted, and the fruiting number (length greater than 5 centimeters) of each group of individual plants is counted after one week, and then each plant is harvested for five consecutive days, and the total harvest of each group of individual plants on 5 days is counted, and each data statistics is in table 4.

[0104] Table 4 Flowering, fruit setting and yield of cucumber plants after root irrigation with different solutions

[0105]

[0106]

[0107] As shown in Table 4, the number of flowering per plant, the number of fruiting per plant, the weight of single fruit, and the harvest per plant of Example 1 are all higher than those of the blank control group and the comparative example group. Compared with the data of the blank control group, Example 1 shows that Example 1 has a significant promoting effect on the flowering of cucumber per plant, the number of fruiting per plant, and the harvest per plant of single fruit weight. In addition, compared with the data of each comparative example, the data of Example 1 are also better than those of the comparative examples, indicating that the specific ratio of the three bacteria of the present invention can maximize the growth-promoting effect of cucumber.

[0108] It should be noted that the above embodiments are only preferred embodiments of the preferred methods of implementing the present invention, rather than all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

Claims

1. A microbial agent for promoting cucumber growth, characterized in that: The following components are included: Achromobacter denitrificans, Bradyrhizobium elkanii, and Azotobacter vinelandii, in a volume ratio of 2:1:1; The denitrifying Achromobacter was purchased from the General Microbiological Center of China Microbiological Culture Collection Administration (CGMCC), with the strain number of CGMCC No.1.2684; the original preservation time was July 11, 2000; The Bradyrhizobium elsdenii was purchased from the General Microbiology Center of China Microorganism Culture Collection Administration (CGMCC), with the strain number of CGMCC No.1.15559; the original storage time was December 30, 2015; The Vinelandia nitrogen-fixing bacteria were purchased from the General Microbiology Center of China Microbiological Culture Collection Administration (CGMCC), with the strain number of CGMCC No.1.7741; the original preservation time was July 24, 2008.

2. The microbial agent for promoting cucumber growth according to claim 1, characterized in that: The viable bacteria count of the denitrifying achromobacter is 1×10 7 cfu / mL; the viable bacterial count of the Bradyrhizobium elsdenii is 1×10 7 cfu / mL; the viable bacterial count of the Vinelandia nitrogen-fixing bacteria is 1×10 7 cfu / mL.

3. The microbial agent for promoting cucumber growth according to claim 1, characterized in that: The microbial agent is a liquid agent.

4. A method for preparing the microbial agent for promoting cucumber growth according to any one of claims 1 to 3, characterized in that: The method comprises the following preparation steps: (1) Thaw the denitrifying Achromobacter and inoculate it into the fermentation medium. Cultivate it at 30°C with a stirring speed of 170 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution; (2) Thaw the Bradyrhizobium elsdenii and inoculate it into the fermentation medium. Cultivate it at 28°C with a stirring speed of 180 r / min until the number of viable cells reaches 1×10 7 cfu / mL of bacterial solution; (3) Thaw the Vinelandia nitrogen-fixing bacteria and inoculate them into the fermentation medium. Cultivate them at 30°C with a stirring speed of 200 r / min until the number of viable bacteria reaches 1×10 7 cfu / mL of bacterial solution; (4) The three bacterial solutions were mixed in a volume ratio of 2:1:1 to obtain the final product microbial agent.

5. Use of the microbial agent according to any one of claims 1 to 3 in promoting the growth of cucumbers.

6. The use of the microbial agent in promoting cucumber growth according to claim 5, characterized in that: The microbial agent is used in promoting seed germination, promoting root elongation, increasing flowering and fruiting rate, increasing single plant yield, plant height, plant biomass and chlorophyll content of cucumber seedlings.

7. The use of the microbial agent in promoting cucumber growth according to claim 6, characterized in that: The application method is seed soaking and root application.

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