Application of bean root exudates in allelopathic effect of hydroponic barley grass

Abstract

The invention belongs to the technical field of plant allelopathy, and particularly relates to application of bean root exudates in allelopathy of hydroponic barley grass. On the basis of a hydroponic barley grass technology, a hydroponic wheat-bean mixed planting mode is created for the first time, allelopathy effects between different bean root exudates and hydroponic barley grass are mined and analyzed by surrounding bean root exudates and utilizing the allelopathy effects among organisms, specific responses of hydroponic barley grass to the bean root exudates in physiological and biochemical indexes are determined, and the method has a good application prospect. And identifying the physicochemical property change of the hydroponic barley grass. A novel method is provided for a novel efficient, safe and environment-friendly bacteriostatic mode of the hydroponic barley grass, a theoretical basis and an improvement direction are provided for developing a novel biological bacteriostatic agent and a hydroponic barley grass planting facility, and a hydroponic wheat and bean mixed planting mode is further promoted to become a planting technology for effectively improving green feed nutrition.

Description

Technical Field

[0001] The present invention belongs to the technical field of allelopathic effects of plants, and specifically relates to the application of root exudates of legumes in the allelopathic effect on hydroponic barley grass. Background Art

[0002] In winter and spring in rural and pastoral areas, green forage grass can hardly grow. In case of natural disasters such as snow disasters and droughts, there is no emergency technology to deal with them. The emergence of hydroponic grass technology has opened up new ways in key issues such as improving land utilization rate, continuous annual supply, and water consumption savings. However, contamination of plug trays and seedlings, and the growth of microorganisms are likely to cause a decline in the growth and quality of green seedlings, becoming the "bottleneck" in the application of this production technology. The traditional chemical reagent sterilization method has low efficiency, incomplete sterilization, questionable safety, and is not easy to be applied on a large scale, which restricts the industrial application of hydroponic grass. Leguminous crops are rich in protein. Mixing the two can, to a certain extent, make up for the energy loss of green forage. However, there is no report on whether there is an antibacterial or allelopathic effect between the two after hydroponic cultivation of wheat and beans. Therefore, it is particularly important to study the antibacterial or allelopathic effect between the two for promoting the mixed planting mode of wheat and beans. Summary of the Invention

[0003] The purpose of the present invention is to provide the application of root exudates of legumes in the allelopathic effect on hydroponic barley grass, and this research provides a theoretical basis and improvement direction for the development of new biological bacteriostatic agents and hydroponic wheat grass planting facilities.

[0004] The present invention provides the application of root exudates of legumes in the allelopathic effect on hydroponic barley grass, and the allelopathic effect includes positive allelopathic effect and negative allelopathic effect.

[0005] As a preferred scheme, the allelopathic effect includes at least one of the following: the influence on the mildew of barley grass, the influence on the germination of barley grass, the influence on the physiological indexes of barley grass, and the influence on the biochemical indexes of barley grass.

[0006] The present invention also provides a biological bacteriostatic agent, which includes root exudates of legumes, and the concentration of the root exudates of legumes is 66.67 - 142.86 g / L.

[0007] As a preferred scheme, the biological bacteriostatic agent further includes Na2CO3 solution, and the mass percentage of Na2CO3 solution is 0.05% - 0.15%; the volume ratio of root exudates of legumes to Na2CO3 solution is 1:1.

[0008] The present invention also provides the application of the biological bacteriostatic agent in reducing the mildew rate of plant growth.

[0009] The present invention also provides a method for reducing the mildew rate during the growth of barley grass, including the following step: treating barley grass with the biological bacteriostatic agent.

[0010] The present invention also provides a method for reducing the negative allelopathic effect of legume root exudates on hydroponic barley grass, which comprises the following steps: treating the barley grass with Na2CO3; the barley grass is the barley grass that generates a negative allelopathic effect after being treated with legume root exudates.

[0011] As a preferred embodiment, the Na2CO3 is a Na2CO3 solution with a mass percentage of 0.05% - 0.15%.

[0012] The present invention also provides a method for reducing the allelopathic effect in hydroponic wheat-bean mixed planting, which comprises the following steps: adding Na2CO3 to the hydroponic solution.

[0013] As a preferred embodiment, the Na2CO3 is a Na2CO3 solution with a mass percentage of 0.05% - 0.15%.

[0014] Beneficial effects: The present invention provides the application of legume root exudates in the allelopathic effect on hydroponic barley grass. Based on the hydroponic barley grass technology, the present invention firstly creates a hydroponic wheat-bean mixed planting mode. Around the legume root exudates, using the allelopathic interaction between organisms, it excavates and analyzes the allelopathic effects between different legume root exudates and hydroponic barley grass, clarifies the specific responses of hydroponic barley grass to legume root exudates in physiological and biochemical indexes, and identifies the changes in the physical and chemical properties of hydroponic barley grass. It provides a new method for a new type of antibacterial method for hydroponic barley grass that is highly efficient, safe and environmentally friendly, provides a theoretical basis and improvement direction for the development of new biological antibacterial agents and hydroponic wheat grass planting facilities, and further promotes the hydroponic wheat-bean mixed planting mode to become a planting technology for effectively improving the nutrition of green forage. Specific embodiments

[0015] The present invention provides the application of legume root exudates in the allelopathic effect on hydroponic barley grass, and the allelopathic effect includes positive allelopathic effect and negative allelopathic effect.

[0016] As a specific embodiment, by comparing the effects of different legume root exudates on the allelopathic effect of hydroponic barley grass, it shows that different legume root exudates all have the effect of reducing mold contamination on hydroponic barley grass, but generally reduce the seed germination vigor, root length growth rate and leaf fresh weight, etc. in physiological indexes. The order of the allelopathic effect strength of different legume root exudates is: black bean > small green lentil > mung bean > red bean > hemp skin pea > red hemp pea > medium-sized soybean. Among them, the black bean has the strongest allelopathic effect on hydroponic barley grass, and the allelopathic effect index is 8.12831, showing a negative allelopathic effect; the medium-sized soybean has the weakest allelopathic effect on hydroponic barley grass, and the allelopathic effect index is 0.56825, showing a positive allelopathic effect.

[0017] As a specific embodiment, the allelopathic effect includes at least one of the following: the effect on the mildew of barley grass, the effect on the germination of barley grass, the effect on the physiological indexes of barley grass, and the effect on the biochemical indexes of barley grass. In the embodiments of the present invention, the effect on the mildew of barley grass includes the effect on the number and growth rate of mildewed barley grass seeds; the effect on the germination of barley grass includes the effect on the germination rate and germination potential of barley grass seeds; the effect on the physiological indexes of barley grass includes the effect on the plant height, fresh weight of leaves, fresh weight of roots, total fresh weight, etc. of barley grass; the effect on the biochemical indexes of barley grass includes the effect on the plasma membrane permeability of roots, plasma membrane permeability of leaves, content of chlorophyll a, content of chlorophyll b, content of total chlorophyll, content of MDA in leaves, content of MDA in roots, content of CAT in leaves, content of CAT in roots, content of POD in leaves, content of POD in roots, and content of soluble sugar in leaves, etc. of barley grass.

[0018] The present invention also provides a biological bacteriostatic agent, which includes legume root exudates, and the concentration of the legume root exudates is 66.67 - 142.86 g / L. As a specific embodiment, the concentration of the legume root exudates is calculated as follows: take 100 g of beans, after soaking, germination acceleration and hydroponics, make the root length of the beans reach 5 - 7 cm, put the beans with a root length of 5 - 7 cm into 1500 mL of high-temperature sterilized deionized water for cultivation for 24 h, and the obtained legume root exudates are defined as the initial concentration of 66.67 g / L. As another specific embodiment, take 100 g of beans, after soaking, germination acceleration and hydroponics, make the root length of the beans reach 5 - 7 cm, put the beans with a root length of 5 - 7 cm into 700 mL of high-temperature sterilized deionized water for cultivation for 24 h, and the obtained legume root exudates are defined as the initial concentration of 142.86 g / L. As a specific embodiment, the root length of the beans can be any one of 5 cm, 6 cm or 7 cm.

[0019] As a specific embodiment, the biological bacteriostatic agent further includes a Na2CO3 solution, and the mass percentage of the Na2CO3 solution is 0.05% - 0.15%. As a specific embodiment, the mass percentage of the Na2CO3 solution can be any one of 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14% or 0.15%; as a specific embodiment, the volume ratio of the legume root exudates to the Na2CO3 solution is 1:1.

[0020] The present invention also provides an application of the biological bacteriostatic agent in reducing the mildew rate of plant growth. As a specific embodiment, experiments show that root exudates of different legumes all have the effect of reducing mold contamination on hydroponic grass. After the root exudates of legumes are combined with Na2CO3 treatment, the harmful effects caused by allelopathy can also be effectively alleviated.

[0021] The present invention also provides a method for reducing the mildew rate during the growth of barley grass, comprising the following step: treating the barley grass with the biological bacteriostatic agent.

[0022] The present invention also provides a method for reducing the allelopathic effect of legume root exudates on hydroponic barley grass, comprising the following steps: treating the barley grass with Na2CO3; the barley grass is the barley grass that produces an allelopathic effect after being treated with legume root exudates. As a specific embodiment, the Na2CO3 is a Na2CO3 solution with a mass percentage of 0.05% - 0.15%. As a specific embodiment, the mass percentage of the Na2CO3 solution can be any one of 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14% or 0.15%.

[0023] As a specific embodiment, after the root exudates of peas are combined with Na2CO3 treatment, different barleys show different allelopathic effects. In terms of physiological indexes, it has a positive promoting effect on the increase of plant height and fresh weight of hydroponic barley grass. Except that there is no significant difference in Ganken Beer No. 7, in the comparison between Ganken Glutinous No. 2 and Ganken No. 5 groups, the treatment effect of the combination of pea root exudates and Na2CO3 is better than that of pea root exudates alone and better than that of Na2CO3 alone. In terms of biochemical indexes, the harm during the growth of hydroponic barley grass is mainly concentrated in the roots. Using the combination of pea root exudates and Na2CO3 treatment can effectively alleviate the harmful effects of harmful substances.

[0024] The present invention also provides a method for reducing the allelopathic effect in hydroponic wheat and bean mixed planting, comprising the following step: adding Na2CO3 to the hydroponic solution. As a specific embodiment, the Na2CO3 is a Na2CO3 solution with a mass percentage of 0.05% - 0.15%. As a specific embodiment, the mass percentage of the Na2CO3 solution can be any one of 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14% or 0.15%.

[0025] Based on the hydroponic wheatgrass technology, the present invention first created a hydroponic wheat-bean mixed planting mode. Focusing on the root exudates of beans and using the allelopathic effect between organisms, it explored and analyzed the allelopathic effects between the root exudates of different beans and hydroponic barley grass, clarified the specific responses of hydroponic barley grass to the root exudates of beans in terms of physiological and biochemical indexes, and identified the changes in the physical and chemical properties of hydroponic barley grass. It provides a new method for a new type of antibacterial method for hydroponic barley grass that is highly efficient, safe, and environmentally friendly, provides a theoretical basis and improvement direction for the development of new biological antibacterial agents and hydroponic barley grass planting facilities, and further promotes the hydroponic wheat-bean mixed planting mode to become an effective technology for improving the nutrition of green fodder.

[0026] To further illustrate the present invention, the following examples are used to describe in detail the application of the root exudates of beans provided by the present invention in the allelopathic effect on hydroponic barley grass, but they should not be construed as limiting the protection scope of the present invention.

[0027] Unless otherwise specified, the present invention has no special requirements for the preparation raw materials, and commercially available products well-known to those skilled in the art can be used.

[0028] The tested barley materials in the present invention are: Ganken 5 (https: / / d.wanfangdata.com.cn / periodical / mlzwxb201304042) (black barley), Ganken Beer 7 (Ganken Beer 7 - Bilibili https: / / www.bilibili.com / video / av583033176 / ?vd_source=83f095dd05a829d5b0efb6e96c6e3e4b) (white hulled barley), Ganken Glutinous 2 (Zhang Xiangping et al., New Barley Varieties Ganken Glutinous 2 and Ganken Beer 8. Acta Triticeae Sinica, 2022.42(3): p. 389.) (white naked barley). The tested bean materials (all commercially available varieties well-known to those skilled in the art) are respectively: medium-grained soybeans, hemp skin peas, mung beans, black beans, red beans, red hemp peas, and small green lentils. The main chemical reagents required are: sodium hypochlorite, anhydrous sodium carbonate.

[0029] Preparation of root exudates of beans: Weigh 100 g of each different bean respectively, soak the seeds in water at room temperature of 28°C for 24 h, lay all the seeds flat in the bean hydroponic device, place it in a dark environment at 30°C for germination, and cover the surface with a wet towel. Take out the hydroponic device and place it in a natural light environment for cultivation. When observing that the root of the bean has elongated to 5 cm, replace it with 1500 mL of high-temperature sterilized deionized water. After 24 h, collect the root extracts of different peas and define the initial concentration as 66.67 g / L (mass / volume). Store at 4°C for later use.

[0030] Example 1 Allelopathic effects of the root exudates of hemp skin peas on different hydroponic grasses

[0031] Select 100 intact seeds each of Ganken 5, Ganken Beer 7, and Ganken Glutinous 2 barley, with 3 replicates for each sample. Place all the barley seeds into a 0.2% sodium hypochlorite solution and take them out after 1 h and lay them flat on filter paper. Pea root exudate group: Starting from the 1st day, spray the extract of pea root exudate of hemp pea on the surface of the barley seeds 3 times a day until they are in a moist state (the dosage is 2 mL each time, and the spraying times are: 8:30 - 9:00 am; 14:00 - 14:30 pm; 20:00 - 20:30 pm); by the 4th day, spray the extract of pea root exudate of hemp pea 2 times on the leaves of the seedlings for treatment (the dosage is 8 - 10 mL each time, and the spraying times are: 8:30 - 9:00 am; 20:00 - 20:30 pm). Control group (CK): Starting from the 1st day, spray high-temperature sterilized deionized water 3 times a day (the dosage is 2 mL each time, and the spraying times are: 8:30 - 9:00 am; 14:00 - 14:30 pm; 20:00 - 20:30 pm); by the 4th day, spray high-temperature sterilized deionized water 2 times on the leaves of the seedlings for treatment (the dosage is 8 - 10 mL each time, and the spraying times are: 8:30 - 9:00 am; 20:00 - 20:30 pm). 0.2% sodium hypochlorite group: Starting from the 1st day, spray 0.2% sodium hypochlorite 3 times a day (the dosage is 2 mL each time, and the spraying times are: 8:30 - 9:00 am; 14:00 - 14:30 pm; 20:00 - 20:30 pm); by the 4th day, spray 0.2% sodium hypochlorite 2 times on the leaves of the seedlings for treatment (the dosage is 8 - 10 mL each time, and the spraying times are: 8:30 - 9:00 am; 20:00 - 20:30 pm).

[0032] Sampling and determination: When the seeds are germinating stably, count the number of germinations, moldy numbers, bud lengths, and plant heights in different culture dishes from the third day until the eighth day. When the eighth day is over, take fresh leaves from different treatments and store them in a refrigerator at 4°C. The remaining materials are dried and ground into powder for later use. Calculate the seed germination potential, growth rate, etc. based on the actual results. According to the references and experimental methods, the chlorophyll content (Zhang Xianzheng. Determination of plant chlorophyll content-acetone ethanol mixture method [J]. Liaoning Agricultural Science, 1986, (03): 26-28.), plasma membrane permeability (Luo Fan et al. Comprehensive Experimental Tutorial of Biotechnology [M]. Sichuan Science and Technology Press, 2023: 176-200.), malondialdehyde, soluble sugar (3. Zhang Zhiliang et al. Plant Physiology Experimental Guide [M]. Higher Education Press, 2012.), and fresh weight of green stems, leaves and roots of seedlings were determined respectively; CAT and POD activities were determined according to the kit method (catalase (CAT) activity detection kit (Cat. No.: BC0200; Brand: Solarbio); peroxidase (POD) activity detection kit (Cat. No.: BC0090; Brand: Solarbio).

[0033] Results: The effects of pea root exudates on the germination and growth of hydroponic barley were determined. As shown in Table 1, the number of moldy plants and the growth rate of moldy plants in 5 days of Ganken 5, Ganken Beer 7 and Ganken Nuo 2 under the treatment of pea root exudates were all lower than those of the control. The number of germinations in 7 days, germination potential in 3 days, plant height, leaf fresh weight and total fresh weight were slightly higher than those of the control, but the difference was not significant. The number of moldy plants and the growth rate of moldy plants in 5 days of the three kinds of barley treated with sodium hypochlorite were all lower than those of the control. The number of germinations in 7 days, germination potential in 3 days, plant height, leaf fresh weight and total fresh weight were all lower than those of the control, and the difference was significant. By comparing the groups, the number of moldy plants and the growth rate of moldy plants under the treatment of pea root exudates were lower than those under the treatment of sodium hypochlorite. The number of germinations in 7 days, germination potential in 3 days, plant height, leaf fresh weight and total fresh weight were all higher than those of the control. Among the varieties, the moldy quantity and mold growth rate of Ganken Beer No. 7 are higher than those of other barleys, but the other indicators are higher than those of other barleys.

[0034] Table 1 Comparison of the effects of root secretions of pea on different physiological parameters of barley

[0035]

[0036] As shown in Table 2, except for Ganken 5, the leaf plasma membrane permeability of Ganken Glutinous 2 and Ganken Beer 7 was slightly higher under the treatment of pea root exudates than that under the sodium hypochlorite treatment, and higher than that of the control. Under the treatment of pea root exudates and sodium hypochlorite, the contents of chlorophyll a, chlorophyll b, and total chlorophyll in Ganken 5 and Ganken Beer 7 were lower than those of the control, but the treatment of pea root exudates among groups was higher than that of sodium hypochlorite in all barley varieties, and the contents of chlorophyll a, chlorophyll b, and total chlorophyll in Ganken Glutinous 2 were higher than those of the control. Except for Ganken Beer 7, the MDA content in the leaves of Ganken 5 and Ganken Glutinous 2 was higher under the treatment of pea root exudates than that under the sodium hypochlorite treatment and higher than that of the control. CAT mainly exists in chloroplasts, and the CAT value under each treatment was correlated with the chlorophyll content, and the results were consistent with the chlorophyll data analysis. Except for Ganken Glutinous 2, the POD values of the leaves of Ganken 5 and Ganken Beer 7 showed that the treatment of pea root exudates was lower than that of sodium hypochlorite treatment, but higher than that of the control.

[0037] Table 2 Comparison of the effects of mungbean pea root exudates on the biochemical indexes of different barleys

[0038]

[0039] Example 2 Effects of mungbean pea root exudates and sodium carbonate treatment on the growth of hydroponic grass

[0040] Weigh 10 g of barley grains of Ganken 5, Ganken Beer 7, and Ganken Glutinous 2 respectively, with 3 replicates for each sample. Put all the barley seeds into 0.2% sodium hypochlorite solution, and take them out after 1 h and spread them out on filter paper. From the 1st day to the 3rd day, all treatments (i.e., the root exudates group of hemp skin peas, 0.1% Na2CO3 group, root exudates of hemp skin peas + 0.1% Na2CO3 group, CK group) were sprayed with autoclaved deionized water 3 times a day (the dosage was 5 mL each time, and the spraying times were: 8:30 - 9:00 am; 14:00 - 14:30 pm; 20:00 - 20:30 pm). From the 4th day, in the root exudates group of hemp skin peas: spray the root exudates of hemp skin peas 2 times a day (the dosage was 5 mL each time, and the spraying times were: 8:30 - 9:00 am; 20:00 - 20:30 pm). From the 6th day to the end of the experiment on the 8th day, spray the root exudates of hemp skin peas 2 times a day (the dosage was 8 - 10 mL each time, and the spraying times were: 8:30 - 9:00 am; 20:00 - 20:30 pm). From the 4th day, in the 0.1% Na2CO3 group: spray 0.1% Na2CO3 by mass 2 times a day (the dosage was 5 mL each time, and the spraying times were: 8:30 - 9:00 am; 20:00 - 20:30 pm). From the 6th day to the end of the experiment on the 8th day, spray 0.1% Na2CO3 by mass 2 times a day (the dosage was 8 - 10 mL each time, and the spraying times were: 8:30 - 9:00 am; 20:00 - 20:30 pm). From the 4th day, in the root exudates of peas + 0.1% Na2CO3 group: spray the root exudates of hemp skin peas + 0.1% Na2CO3 by mass (the volume ratio of the root exudates of hemp skin peas to 0.1% Na2CO3 by mass was 1:1) (spray 5 mL of the root exudates of hemp skin peas at 8:00 - 8:30 am and spray 5 mL of 0.1% Na2CO3 at 20:00 - 20:30 pm). From the 6th day to the end of the experiment on the 8th day, spray the root exudates of hemp skin peas + 0.1% Na2CO3 by mass 2 times a day (spray 8 - 10 mL of the root exudates of hemp skin peas at 8:00 - 8:30 am and spray 8 - 10 mL of 0.1% Na2CO3 at 20:00 - 20:30 pm). From the 4th day, in the CK group: spray autoclaved deionized water 2 times a day (the dosage was 5 mL each time, and the spraying times were: 8:30 - 9:00 am; 20:00 - 20:30 pm). From the 6th day to the end of the experiment on the 8th day, spray autoclaved deionized water 2 times a day (the dosage was 8 - 10 mL each time, and the spraying times were: 8:30 - 9:00 am; 20:00 - 20:30 pm).

[0041] Sampling and determination: When the seeds are germinating stably, count the number of germinations, moldy numbers, bud lengths, and plant heights in different culture dishes from the third day until the eighth day. When the eighth day is over, take fresh leaves after different treatments and store them in a refrigerator at 4°C. The remaining materials are dried and ground into powder for later use. Calculate the seed germination potential, growth rate, etc. based on the actual results. According to the references and experimental methods, the chlorophyll content (Zhang Xianzheng. Determination of plant chlorophyll content-acetone ethanol mixture method [J]. Liaoning Agricultural Science, 1986, (03): 26-28.), plasma membrane permeability (Luo Fan et al. Comprehensive Experimental Tutorial of Biotechnology [M]. Sichuan Science and Technology Press, 2023: 176-200.), malondialdehyde, soluble sugar (3. Zhang Zhiliang et al. Plant Physiology Experimental Guide [M]. Higher Education Press, 2012.), and fresh weight of green stems, leaves and roots of seedlings were determined respectively; CAT and POD activities were determined according to the kit method (catalase (CAT) activity detection kit (Cat. No.: BC0200; Brand: Solarbio); peroxidase (POD) activity detection kit (Cat. No.: BC0090; Brand: Solarbio).

[0042] Results: As shown in Table 3, the plant height, leaf and root fresh weight of Ganken 5 were higher than those of the control under the treatment of pea root exudates + 0.1% Na2CO3. The 0.1% Na2CO3 treatment significantly reduced the leaf, root and total fresh weight compared with the control, but significantly increased the growth rate of plant height of the three barley species. All the indicators of pea root exudates were slightly lower than those of the control. The plant height of Gankenpi 7 was higher than that of the control under the treatment of pea root exudates + 0.1% Na2CO3, and the plant height growth rate, leaf fresh weight and root fresh weight were slightly lower than those of the control. The 0.1% Na2CO3 treatment significantly reduced the other indicators. The leaf and root fresh weight of pea root exudates were higher than those of the control. Under different treatments, except for the highest root fresh weight in the treatment of pea root exudates + 0.1% Na2CO3, the plant height, plant height growth rate, leaf and root fresh weight of Gankennuo No. 2 were all lower than those of the control. Among the groups, the comparison was pea root exudates + 0.1% Na2CO3 treatment > pea root exudates treatment > 0.1% Na2CO3.

[0043] Table 3 Comparison of the effects of root exudates of pea and sodium carbonate treatment on different physiological parameters of barley

[0044]

[0045]

[0046] As shown in Table 4 and Table 5, compared with the control, for the pea Ganken 5 under the treatment of pea root exudates + 0.1% Na2CO3, the contents of chlorophyll a, chlorophyll b, total chlorophyll, the plasma membrane permeability of leaves and roots, the soluble sugars in leaves and roots, the CAT in roots, and the POD in leaves and roots all decreased, and there was no significant difference in the MDA content in roots and leaves compared with the control. Under the treatment of 0.1% Na2CO3, the plasma membrane permeability of roots, chlorophyll a, chlorophyll b, total chlorophyll content, and the soluble sugars in leaves and roots were all higher than those of the control, and there was no significant difference in the MDA content in roots and leaves compared with the control. Under the treatment of pea root exudates, the plasma membrane permeability of roots, the MDA in roots, and the soluble sugars in leaves and roots were all higher than those of the control, while the chlorophyll and CAT contents were lower than those of the control; among them, the inter-group plasma membrane permeability: pea root exudates + 0.1% Na2CO3 < pea root exudates < 0.1% Na2CO3.

[0047] For Ganken Beer 7 under the treatment of pea root exudates + 0.1% Na2CO3, except that the contents of chlorophyll a, chlorophyll b, and total chlorophyll were significantly lower than those of the control, the other indexes were all higher than those of the control. Under the treatment of 0.1% Na2CO3, except that the MDA in roots and leaves was higher than that of the control, the other indexes were all lower than those of the control. Under the treatment of pea root exudates, the plasma membrane permeability of roots, chlorophyll b, and the soluble sugars in leaves were all higher than those of the control, and the other indexes were all lower than those of the control; among them, the inter-group plasma membrane permeability: 0.1% Na2CO3 > pea root exudates > pea root exudates + 0.1% Na2CO3.

[0048] For Ganken Glutinous 2 under the treatment of pea root exudates + 0.1% Na2CO3, the contents of chlorophyll a, chlorophyll b, total chlorophyll, the MDA in roots, the soluble sugars in roots, and the CAT in roots and leaves were all lower than those of the control. Under the treatment of 0.1% Na2CO3, except that the plasma membrane permeability of roots was higher than that of the control, the other indexes were all lower than those of the control. Under the treatment of pea root exudates, the plasma membrane permeability of roots and the soluble sugars in leaves were all higher than those of the control, and the other indexes were all lower than those of the control; among them, the inter-group plasma membrane permeability: pea root exudates + 0.1% Na2CO3 < pea root exudates < 0.1% Na2CO3.

[0049] Table 4 Comparison of the effects of hemp pea root exudates and sodium carbonate treatments on the biochemical indexes of different barleys - 1

[0050]

[0051] Table 5 Comparison of the effects of hemp pea root exudates and sodium carbonate treatments on the biochemical indexes of different barleys - 2

[0052]

[0053]

[0054] Example 3 Allelopathic Effects of Root Exudates of Different Legumes on Hydroponic Barley Grass

[0055] Take 100 intact grains of Gankeng Beer No. 7 and set 3 replicates. Put all barley seeds into 0.2% sodium hypochlorite solution and take them out after 1 h and lay them flat on filter paper. Different root exudate groups: Starting from the 1st day, spray the root exudate extracts of different legumes (medium-sized soybeans, hemp skin peas, mung beans, black beans, red beans, red hemp peas, small green lentils) on the surface of barley seeds 3 times a day (the dosage is 2 mL each time, and the spraying times are: 8:30 - 9:00 am; 2:00 - 2:30 pm; 8:00 - 8:30 pm) until it is in a moist state. When the bud length is about 1 cm on the 4th day, spray the root exudate extracts of different legumes on the leaves of the seedlings and grass 2 times (the dosage is 8 - 10 mL each time, and the spraying times are: 8:30 - 9:00 am; 8:00 - 8:30 pm). CK group: The spraying amount and spraying time of the control group are the same as those of the different root exudate groups, but the legume root exudates are replaced with high-temperature sterilized deionized water.

[0056] Sampling and determination: After the seeds germinate stably, count the germination number, moldy number, bud length, and plant height of different petri dishes starting from the 3rd day until the 8th day. After the experiment ends on the 8th day, store the fresh leaves after different treatments in a 4°C refrigerator, and kill the remaining materials by blanching and drying them, then grind them into powder for later use. Calculate the seed germination potential, growth rate, etc. according to the actual results. According to the references and experimental methods, determine the chlorophyll content (Zhang Xianzheng. Determination of plant chlorophyll content - acetone ethanol mixture method [J]. Liaoning Agricultural Sciences, 1986, (03): 26 - 28.), plasma membrane permeability (Luo Fan et al. Comprehensive Experimental Course of Biotechnology [M]. Sichuan Science and Technology Press, 2023: 176 - 200.), malondialdehyde, soluble sugar (3. Zhang Zhiliang et al. Experimental Guide for Plant Physiology [M]. Higher Education Press, 2012.), fresh weight of the green stems, leaves and roots of the seedlings; the activities of CAT and POD are determined with reference to the kit method (Catalase (CAT) Activity Detection Kit (product number: BC0200; brand: Solarbio); Peroxidase (POD) Activity Detection Kit (product number: BC0090; brand: Solarbio)).

[0057] Result analysis: As shown in Table 6, except for hemp pea and mung bean, the 3-day germination potential of the secretions of the other beans is lower than that of the control. Among them, the germination potential of hemp pea is the highest at 0.713, and that of small green lentil is the lowest at 0.297. Except for hemp pea, the germination number of the other beans' root exudates at 7 days is lower than that of the control. The number of moldy beans is the highest in red hemp pea and the lowest in mung bean. All the root exudates of the beans can significantly reduce the number of mold contamination, and the root growth rate, fresh leaf weight, and fresh root weight are generally lower than those of the control, but the overall mold growth rate is significantly higher than that of the control.

[0058] Table 6 Comparison of the effects of root exudates of different beans on the physiological indexes of hydroponic barley grass

[0059]

[0060] As shown in Table 7, except that the plasma membrane permeability of red bean roots and the plasma membrane permeability of black bean leaves are lower than those of the control, the secretions of the other beans are higher than those of the control. The total chlorophyll content of all the root exudates of the beans is higher than that of the control, and there is no significant difference in the MDA content. After further calculating the allelopathic effect index, as shown in Table 8, the allelopathic effect of the root exudates of different beans from strong to weak is: black bean > small green lentil > mung bean > red bean > hemp pea > red hemp pea > medium-sized soybean. Among them, the absolute value of the allelopathic effect index of black bean is the largest, at 8.12831, and that of medium-sized soybean is the smallest, at 0.56825. Among them, medium-sized soybean and red hemp pea show positive allelopathic effects on hydroponic grass, and the root exudates of the other beans show negative allelopathic effects on hydroponic grass, among which the negative allelopathic effect of hemp pea is the weakest.

[0061] Table 7 Comparison of the effects of root exudates of different beans on the biochemical indexes of hydroponic barley grass

[0062]

[0063]

[0064] Table 8 Comparison of allelopathic effect indexes of root exudates of different beans

[0065]

[0066]

[0067] Note: R1 total: The sum of all allelopathic effect indexes. R1 total < 0: Inhibitory effect (i.e., negative allelopathic effect); R1 total > 0: Promoting effect (i.e., positive allelopathic effect). The absolute value size represents the strength of allelopathic effect.

[0068] Conclusion: By comparing the allelopathic effects of hemp-peeled peas on the germination and growth of different barleys, it is shown that both sodium hypochlorite and pea root exudate treatments can reduce the number of moldy barleys and the pollution rate in hydroponic barley grass. However, in terms of other physiological indicators such as germination, pea root exudates showed a better positive effect than sodium hypochlorite treatment. In terms of biochemical indicators, it is speculated that although pea root exudates can reduce the accumulation of harmful substances caused by mold stress to a certain extent, when the mold is not severe, the root exudates of hemp-peeled peas, as a type of acidic substance, act together with the acidic substances secreted by hydroponic barley grass itself, aggravating the stress damage of hydroponic barley grass.

[0069] The sodium carbonate treatment and the treatment with hemp-peeled pea root exudates were added in the later growth stage. After combining the hemp-peeled pea root exudates with the sodium carbonate treatment, different barleys showed different allelopathic effects. In terms of physiological indicators, it had a positive promoting effect on the increase in plant height and fresh weight of hydroponic barley grass. Except for the insignificant difference in Gankenpi 7, in the comparison between Gankenuo 2 and Ganken 5, the effect of combining the hemp-peeled pea root exudates with the sodium carbonate treatment was better than that of the hemp-peeled pea root exudates alone and better than that of the sodium carbonate alone. In terms of biochemical indicators, the harm during the growth process of hydroponic barley grass mainly concentrated on the roots. Using the combination of hemp-peeled pea root exudates and sodium carbonate treatment could effectively alleviate the harmful effects of harmful substances.

[0070] By comparing the allelopathic effects of root exudates of different legumes on hydroponic barley grass, it is shown that the root exudates of different legumes all have the effect of reducing mold contamination on hydroponic barley grass, but generally reduce the seed germination vigor, root growth rate, and leaf fresh weight in terms of physiological indicators. Among them, black beans have the strongest negative allelopathic effect on hydroponic barley grass, and hemp-peeled peas have the weakest negative allelopathic effect. With the extension of the cultivation time, the potential harmful effects of different legumes on the leaves and roots of hydroponic barley grass may gradually increase. At the same time, existing technologies show that the color of the bean epidermis is related to its antioxidant and other functions, but in this experiment, there is no significant correlation between the color of the beans and the antibacterial strength. In actual hydroponic mixed planting production of wheat and beans, it is necessary to consider that the two crops have the same growth rate, or when adding exogenous root exudates, it is necessary to consider the allelopathic strength and the harm of negative feedback effects.

[0071] Thus, the present invention for the first time creates a hydroponic wheat-bean mixed planting mode on the basis of the hydroponic wheat grass technology. Around the root exudates of legumes, using the allelopathic effect between organisms, it explores and analyzes the allelopathic effects between the root exudates of different legumes and hydroponic barley grass, clarifies the specific responses of hydroponic barley grass to the root exudates of legumes in terms of physiological and biochemical indicators, and identifies the changes in the physical and chemical properties of hydroponic barley grass. It provides a new method for a new antibacterial method for hydroponic barley grass that is highly efficient, safe, and environmentally friendly, provides a theoretical basis and improvement direction for the development of new biological antibacterial agents and hydroponic barley grass planting facilities, and further promotes the hydroponic wheat-bean mixed planting mode to become a planting technology for effectively improving the nutrition of green forage.

[0072] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, rather than all of them. People can also obtain other embodiments based on this embodiment without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Application of legume root exudates in allelopathic effect on hydroponic barley grass, characterized in that, The allelopathic effect includes positive allelopathic effect and negative allelopathic effect.

2. The application according to claim 1, wherein The allelopathic effect includes at least one of the following: the effect on the mildew of barley grass, the effect on the germination of barley grass, the effect on the physiological indexes of barley grass, and the effect on the biochemical indexes of barley grass.

3. A biological bacteriostatic agent, characterized in that, The biological bacteriostatic agent includes the root exudates of legumes, and the concentration of the root exudates of legumes is 66.67 - 142.86 g / L.

4. The biological bacteriostatic agent according to claim 3, characterized in that, The biological bacteriostatic agent also includes a Na2CO3 solution, and the mass percentage of the Na2CO3 solution is 0.05% - 0.15%; the volume ratio of the root exudates of legumes to the Na2CO3 solution is 1:

1.

5. Application of the biological bacteriostatic agent according to claim 3 or 4 in reducing the mildew rate of plant growth.

6. A method for reducing the mildew rate during the growth of barley grass, characterized in that, It includes the following steps: treating barley grass with the biological bacteriostatic agent according to claim 3 or 4.

7. A method for reducing the negative allelopathic effect of legume root exudates on hydroponic barley grass, characterized in that, It includes the following steps: Treating barley grass with Na2CO3; the barley grass is the barley grass that produces a negative allelopathic effect after being treated with the root exudates of legumes.

8. The method according to claim 7, characterized in that, The Na2CO3 is a Na2CO3 solution with a mass percentage of 0.05% - 0.15%.

9. A method for reducing the negative allelopathic effect in hydroponic mixed cultivation of wheat and broad beans, characterized in that, It includes the following steps: Adding Na2CO3 to the hydroponic solution.

10. The method according to claim 9, wherein The Na2CO3 is a Na2CO3 solution with a mass percentage of 0.05% - 0.15%.

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