Water culture system and water culture method for tartary buckwheat during whole growth period

Abstract

The application discloses a whole growth period water culture system and method for tartary buckwheat, and relates to the field of agricultural technology. The system comprises a water culture plate for seed germination of tartary buckwheat, a container for seedling transplanting, and a lamp plate for providing illumination. The method based on the system comprises the following steps: germination; seedling transplanting: adding a nutrient solution with a concentration of n into the container, planting tartary buckwheat seedlings after germination into the cracks of the foam plate and placing the foam plate in the container, and placing the container in a ventilated place; applying standard intensity illumination to the seedlings through the lamp plate; nutrient growth period: reducing the addition amount of the nutrient solution, so that at least one third of the root system of the tartary buckwheat is exposed to air between the liquid surface and the foam plate; and propagation period: from the present budding period to the grain filling period, the concentration of the nutrient solution and the illumination intensity are sequentially increased in each cycle.

Description

Technical Field

[0001] This application relates to the field of agricultural technology, and in particular to a hydroponic system and method for the entire growth period of buckwheat. Background Technology

[0002] Buckwheat is a special grain crop that can be used for both food and medicine. It is a harmless Chinese medicinal material that has been transformed into a staple food in my country and occupies an important position. Buckwheat is rich in flavonoids, polyphenols, proteins, dietary fiber and other bioactive compounds, and has the effect of lowering "three highs" (high blood pressure, high blood sugar, and high cholesterol).

[0003] Currently, buckwheat is mainly cultivated in the mountainous areas of southwestern China, such as Sichuan and Guizhou. With the deepening development of buckwheat's functional components and the exploration of its tolerance to poor soil conditions, hydroponic experiments related to buckwheat's stress resistance and the nutritional quality of its sprouts are increasing year by year. However, these experiments are currently limited to the seedling stage. The changes in buckwheat plants after they enter vegetative growth are difficult to conduct due to the limitations of hydroponic technology. For large-scale standardized buckwheat hydroponics, there are existing devices capable of hydroponically cultivating buckwheat during the seedling stage. However, these devices rely on an integrated circulating system, making it impossible to treat each buckwheat seedling individually, thus failing to meet experimental needs, and the cost is relatively high. While there are experimental devices for hydroponically cultivating buckwheat seedlings, these only address the issue of seedling hypoxia and do not meet the requirements of complex experimental environments. In summary, if a full-growth-cycle hydroponic experiment is to be conducted, current hydroponic technology can only perform single-treatment of buckwheat, failing to meet the needs of complex experimental treatments, and no invention has yet demonstrated the growth of buckwheat throughout its entire growth cycle. Summary of the Invention

[0004] To address at least one of the aforementioned problems, this application provides a hydroponic system and method for the entire growth cycle of buckwheat.

[0005] To achieve the above objectives, this application provides a hydroponic system for the entire growth cycle of buckwheat, comprising: A hydroponic tray for germinating buckwheat seeds, wherein the hydroponic tray is provided with water-absorbing material and the top of the hydroponic tray is covered with a film; A container for transplanting seedlings, the container having a variable diameter with its upper diameter being larger than its lower diameter, the container having a foam board inside, the foam board having at least one through slit, and the diameter of the foam board being between the upper diameter and the lower diameter of the container; A light panel for providing illumination is disposed on the culture rack, and the container is disposed at the lower part of the culture rack.

[0006] One embodiment of the present invention is that the absorbent material includes toilet paper, cotton, and transplanted cotton; each of the through-slits has a groove at one end facing the bottom of the container, the through-slit passes through the groove, the thickness of the foam board is no more than 1 cm, and the length of the through-slit is 4-5 cm; the maximum light intensity provided by the lamp panel is no less than 40000 lx; ​​the cultivation rack has several layers, the height of each layer of the cultivation rack is at least 20 cm higher than the height of the buckwheat plant, and each layer of the cultivation rack is equipped with a lamp panel.

[0007] Another object of the present invention is to provide a hydroponic method for buckwheat throughout its entire growth period, comprising the following steps: S1. Germination: Take buckwheat seeds, disinfect, clean and soak them, and then germinate them in a hydroponic tray; S2. Transplanting and planting: Add nutrient solution of concentration n to the container, take the germinated buckwheat seedlings and plant them in the cracks of the foam board and place them in the container, ensuring that the foam board is floating, and place the container in a ventilated place; apply the reference intensity of light to the seedlings through the lamp board. S3, vegetative growth period: reduce the amount of nutrient solution added so that at least one-third of the buckwheat roots are exposed to the air between the liquid surface and the foam board; S4. Propagation period: From the budding stage to the grain-filling stage, the nutrient solution concentration and light intensity are increased sequentially in each cycle.

[0008] The beneficial effects of the present invention are as follows: 1. The hydroponic device of the present invention avoids the need for an integrated nutrient solution circulation system and an oxygenation device for seedling hydroponics required for conventional hydroponic buckwheat. Normal development of seedlings can be guaranteed by using conventional hydroponic equipment. Individual plants can be treated, the entire life cycle of buckwheat can be observed, it can be used for experimental research, and it also provides ideas for the hydroponic domestication of other crops.

[0009] 2. The hydroponic method of the present invention sets the spacing, water spraying method and light intensity reasonably during the seed germination period to ensure the excellent development of the root system and stem of the seed from germination to transplanting, and enhances the adaptability of seedlings to the new environment after transplanting; the use of foam board and non-porous flower pots for planting simplifies the planting device.

[0010] 3. Assisted hulling treatment is applied to buckwheat seedlings to accelerate cotyledon development, promote timely growth of true leaves, and enhance seedling resistance to diseases. A well-ventilated environment is selected to accelerate air circulation, prevent pathogen accumulation, and reduce seedling disease incidence. Various nutrients are supplemented promptly during the plant's growth period to ensure morphological development is consistent with field cultivation. During the propagation period, light intensity and nutrient solution concentration are adjusted synchronously to improve the seed setting rate of hydroponically grown buckwheat. This invention is the first to propose a hydroponic method for the entire life cycle of buckwheat, providing a feasible solution for standardized buckwheat cultivation. Attached Figure Description

[0011] Figure 1 The effect of setting the spacing during buckwheat seed germination on the mold rate; Figure 2 The effect of temperature on germination rate of buckwheat seeds; Figure 3 The effect of water spraying and light-shielding operation during buckwheat seed germination on taproot length; Figure 4 The effect of light intensity on stem length of buckwheat seedlings before transplanting; Figure 5 The effect of manual shelling on the shelling rate; Figure 6 The impact of ventilation environment on morbidity and mortality; Figure 7 To supplement the effects of calcium nitrate on the growth of buckwheat; Figure 8 The effect of chelated iron spraying on the photosynthetic pigment content of chlorotic young leaves; Figure 9 The effect of gibberellin spraying on the breeding period of tartary buckwheat; Figure 10 To investigate the effects of nutrient solution concentration and light intensity on the fruit setting rate. Detailed Implementation

[0012] The technical solution of this application will be clearly described below with reference to the embodiments thereof. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the protection scope of this application.

[0013] In this embodiment, germination refers to the germination of a seed until the hypocotyl is observed to break through the seed coat; when transplanting seedlings, the main root of the germinated seed should be about 3 cm long and the stem should be more than 1 cm long.

[0014] In this embodiment, the vegetative growth period refers to the growth stage between when the seedling grows three true leaves and when it begins to bud.

[0015] In this embodiment, the early stage of grain filling refers to the period when 20%-30% of the flowers on the main stem begin to bear fruit. The seeds are very small, soft, and light green in color. They are easily deformed by hand and there is no endosperm accumulation inside.

[0016] In this embodiment, the early to mid-stage of grain filling refers to the rapid growth of seeds, reaching a length of 4-4.5 mm and a width of 2-2.5 mm. The seeds are soft in texture, light green in color, and easily deformed by hand. They contain a small amount of milky white paste-like endosperm or have no endosperm accumulation. More than 50% of the seeds in the whole plant reach this state.

[0017] In this embodiment, the mid-stage of grain filling refers to the period when the seed continues to grow, reaches a length of 5-6 mm and a width of 3-4 mm, the seed coat begins to harden, the seed texture becomes hard, and it turns dark green. It is not easily deformed when gently squeezed by hand, and there is an accumulation of milky white pasty endosperm inside. More than 50% of the seeds of the whole plant reach this state.

[0018] In this embodiment, the mid-to-late stage of grain filling refers to the seed being fully developed, with its length reduced to 4-6 mm and its width reaching 4-4.5 mm. The seed coat is completely hardened, the seed texture is hard, the seed coat begins to turn yellow or yellowish-brown, it does not deform when gently squeezed by hand, and white or yellow solid endosperm is formed inside. More than 50% of the seeds of the whole plant have reached this state.

[0019] In this embodiment, the late stage of grain filling refers to the final black or yellow color of the seeds. Based on the color of mature seeds of each variety, more than 50% of the seeds of the whole plant have reached this state.

[0020] Example 1: A hydroponic system for the entire growth period of buckwheat, comprising: A hydroponic tray for germinating buckwheat seeds, wherein the hydroponic tray is provided with water-absorbing material and the top of the hydroponic tray is covered with a film; A container for transplanting seedlings, the container having a variable diameter with its upper diameter being larger than its lower diameter, the container having a foam board inside, the foam board having at least one through slit, and the diameter of the foam board being between the upper diameter and the lower diameter of the container; A light panel for providing illumination is disposed on the culture rack, and the container is disposed at the lower part of the culture rack.

[0021] For the aforementioned hydroponic tray, a conventional hydroponic tray can be used, which can be purchased directly from the market. In this embodiment, the length, width, and height of the hydroponic tray used are 34cm, 24cm, and 4cm, respectively. For the membrane material on top of the hydroponic tray, similar to existing hydroponics methods, a thin and transparent membrane material is usually chosen, such as conventional PP film or PVC film. Its main function is to maintain humidity within the hydroponic tray and reduce water evaporation. As for the absorbent material, its main function is to serve as a carrier for the germination of buckwheat seeds, keeping them moist. Common planting cotton can be used as an absorbent material, or cheaper cotton or even toilet paper can be chosen.

[0022] The aforementioned containers are primarily used to provide a hydroponic growth environment for buckwheat from seedling to propagation stages. Common options include large-top-small-bottom flowerpots, or custom-made larger hydroponic trays. Inside the container is a foam board, which is crucial for achieving full-cycle hydroponics of buckwheat: the foam board has at least one through-slit, such as 1, 3, 6, 10, or even more, depending on the size of the foam board. During transplanting, the buckwheat seedlings are planted into the container through this through-slit. The diameter of the foam board is between the upper and lower diameters of the container, allowing it to be secured in the middle of the container when needed. The through-slits on the foam board should not be too long, as excessively long through-slits make it difficult to provide adequate clamping force in the early stages of buckwheat seedling growth; the through-slits should not be too short, as short through-slits will cause the buckwheat seedlings to be clamped too tightly and are not conducive to the subsequent growth of the buckwheat stems. Therefore, after extensive experiments by the inventors, and considering the characteristics of buckwheat plants, the slit length was set at 4-5 cm. As for the thickness of the foam board, it only needs to be sufficient to support the growth of the buckwheat seedlings. In the later stages of buckwheat growth, the buckwheat is mainly supported by the root system and the container, so it does not need to be very thick. It can be set to 3-10 mm, such as 3 mm, 5 mm, 6 mm, 8 mm, and 10 mm.

[0023] Specifically, for the through-slit, a groove can be set on the side near the bottom of the container. To ensure the strength of the foam board, the depth of the groove should not exceed 1 / 2 of the depth of the foam board, while its width is not limited, as long as it does not affect the growth of the remaining buckwheat seedlings. The part of air in the groove allows a small number of buckwheat roots to be exposed to the air during the seedling stage, and the air humidity in the groove is relatively high, usually close to the saturation water content, so it will not cause these roots to dehydrate.

[0024] Meanwhile, to facilitate container placement and provide the necessary light for buckwheat growth, a light panel and at least one cultivation rack are provided. The cultivation rack can be single-layered or multi-layered. When using multi-layered racks, the height of each layer must be at least 20cm higher than the height of the buckwheat plant. For example, the height of existing buckwheat plants ranges from 30 to 70cm depending on the variety. The appropriate rack height can be selected based on the specific buckwheat variety. The light panel is located at the top of the cultivation rack. In some cases, a corresponding light panel can also be installed on the side of the cultivation rack. In this embodiment, the maximum light intensity provided by the light panel is not less than 40,000 lx.

[0025] Example 2, a hydroponic method for the entire growth period of buckwheat, includes the following steps: S1. Germination: Take buckwheat seeds, disinfect, clean and soak them, and then germinate them in a hydroponic tray; In this step, the specific disinfection, cleaning, and soaking operations are as follows: First, disinfect the buckwheat seeds with 1% sodium hypochlorite for 5-15 minutes, such as 5 minutes, 8 minutes, 10 minutes, 12 minutes, and 15 minutes; after disinfection, wash the buckwheat seeds with water to remove residual sodium hypochlorite; after washing, soak the buckwheat seeds in water for 6-8 hours. After soaking, remove the buckwheat seeds that float on the surface of the water, and the remaining seeds can be used for germination in a hydroponic tray.

[0026] Next, thoroughly moisten the absorbent material in the hydroponic tray with water, then place the soaked buckwheat seeds on the absorbent material, control the temperature at 20~23℃, and cover the hydroponic tray with a film to ensure the humidity for buckwheat seed germination and increase the germination rate; after the buckwheat seeds have grown taproots, apply 2000~5000 lx of light to the hydroponic tray and continue to grow for 3~6 days.

[0027] In some embodiments, when the soaked buckwheat seeds are placed on the absorbent material, the spacing between the buckwheat seeds is set to 0.6~1cm, such as... Figure 1 As shown, under these conditions, compared with random sowing, setting the spacing between buckwheat seeds to 0.6~1.0cm significantly reduced the mold rate by 43.3%.

[0028] In some embodiments, before the buckwheat seeds root, the temperature is maintained at 20-23°C, and the absorbent material is periodically sprayed with water for 10-12 hours. Figure 2 As shown, a suitable temperature can greatly improve the germination rate of buckwheat seeds.

[0029] In some implementations, after the buckwheat seeds have rooted and come into contact with the absorbent material, the absorbent material is kept moist for 8 hours. Then the film is opened, and water is sprayed once horizontally above the hydroponic tray, followed by 10-15 hours of growth in the dark. This process can significantly increase the length of the taproot of the buckwheat seeds. Figure 3 As shown, using the method of this embodiment, compared to the conventional method of spraying water twice, the length of the taproot increases by 73.7%. Those skilled in the art will know that during seed germination, the longer the taproot, the better the seed absorbs water and minerals after germination, resulting in stronger seedlings.

[0030] In some implementations, after the period of growth in the dark, water is sprayed into the hydroponic tray to moisten the absorbent material, and the plant is grown for 3-6 days under light conditions of 2000-5000 lx, with a daily light duration of 8 hours to mimic the light conditions under natural growth conditions. Figure 4As shown, when the light intensity is 2000~5000 lx, the stem length can be controlled within a suitable range. In particular, when the light intensity is 3000 lx, subsequent increases in light intensity have little effect on the stem length. It is known to those skilled in the art that for seedlings, excessively long stems can lead to a fragile structure and insufficient vigor, thus affecting growth.

[0031] S2. Transplanting and planting: Add nutrient solution of concentration n to the container, take the germinated buckwheat seedlings and plant them in the cracks of the foam board and place them in the container, ensuring that the foam board is floating, and place the container in a ventilated place; apply the reference intensity of light to the seedlings through the lamp board. In this step, the nutrient solution is Hoagland standard nutrient solution, whose stock solution includes the following components: calcium nitrate tetrahydrate 945 mg / L, potassium nitrate 607 mg / L, ammonium dihydrogen phosphate 115 mg / L, magnesium sulfate heptahydrate 493 mg / L, ferric disodium ethylenediaminetetraacetate 40 mg / L, boric acid 2.86 mg / L, manganese sulfate 2.13 mg / L, zinc sulfate 0.22 mg / L, copper sulfate 0.08 mg / L, and ammonium molybdate 0.02 mg / L. When using, it is prepared according to the ratio of stock solution to water of 1:100 and added to the container. The reference intensity refers to a light intensity of 20000 lx.

[0032] This step also includes manual assisted hulling. For buckwheat, its cotyledons are relatively large, resulting in poor ability to emerge from the soil. Furthermore, compared to soil cultivation, the lack of soil matrix means the stems don't experience friction with the soil during growth, leading to a longer automatic hulling time and impacting subsequent growth. Therefore, this step includes a manual assisted hulling process. This manual hulling method includes: using tweezers to hold the seed coat, or wrapping gauze around the top of the seedling or stem and then pulling the gauze to assist hulling. Manual hulling is performed when more than 50% of the buckwheat seedlings have hulled. The final hulling result is as follows: Figure 5 As shown.

[0033] When manually removing the seed coat with tweezers, select seedlings whose seed coat has been pushed up and whose cotyledons are exposed. Hold the top of the seed coat with tweezers and pinch the exposed cotyledon part with the other hand. Use the tweezers to slowly and forcefully remove the seed coat upwards, avoiding damage to the buckwheat cotyledons.

[0034] When manually removing the seeds using gauze, gently wrap the gauze around the curved top of the plant and the stem to cover the plant, simulating the friction between buckwheat seeds and soil in the field, thus assisting in the removal of the seeds. Remove the gauze promptly after the seeds have been removed from the shell.

[0035] In this step, placing the container in a well-ventilated area is crucial for reducing the disease and mortality rates of buckwheat seedlings. Figure 6 As shown, where, Figure 6(A) in the figure represents the relationship between morbidity and ventilation environment. Figure 6 (B) shows the relationship between mortality rate and ventilation environment. Compared with windowless rooms, rooms with windows and ventilated corridors, open ventilation corridors with better ventilation have reduced morbidity by 85%, 83.27%, and 82.05%, and reduced mortality by 92.83%, 92.22%, and 91.63%, respectively.

[0036] The reference intensity of illumination mentioned in this step refers to illumination with an intensity of 20,000 lx, which imitates natural illumination, and the illumination time is usually 8~12h / d.

[0037] Similar to conventional hydroponics, in this embodiment, during the seedling stage after transplanting, i.e., when there are 1-3 true leaves, the nutrient solution is usually changed every 5-7 days. At the same time, when the temperature is high in summer, the water evaporation is greater, so it is necessary to add nutrient solution during the interval between nutrient solution changes.

[0038] Meanwhile, this step, as well as subsequent steps S3 and S4, also include the application of calcium nitrate and chelated iron: when precipitation occurs in the nutrient solution, calcium hydroxide is used to adjust the pH of the nutrient solution to 6-7, and 472 mg / L of calcium nitrate is added to the nutrient solution, of which 25 ml of calcium nitrate is added for every 800 ml of nutrient solution. After 5-10 days, the buckwheat is sprayed with the same concentration of calcium nitrate again; when the young leaves of buckwheat lose their green color, chelated iron at a concentration of 0.1 wt% is sprayed on the leaves.

[0039] Supplementing with calcium nitrate has significant benefits for the overall growth of buckwheat and can also reduce disease incidence. (See [link to relevant documentation]). Figure 7 ,in, Figure 7 (A) in the figure represents the effect of calcium nitrate supplementation on total root length. Figure 7 (B) indicates the effect of calcium nitrate supplementation on total root length. Figure 7 (A) in the figure represents the effect of calcium nitrate supplementation on total root length. Figure 7 (A) in the figure represents the effect of calcium nitrate supplementation on the average root diameter. Figure 7 (C) in the figure represents the effect of calcium nitrate supplementation on root volume. Figure 7 (D) in the figure represents the effect of calcium nitrate supplementation on the number of root tips. Figure 7 (E) in the figure represents the effect of calcium nitrate supplementation on leaf dry weight. Figure 7 (F) in the figure represents the effect of calcium nitrate supplementation on root dry weight. Figure 7 In the figure (G), it represents the effect of calcium nitrate supplementation on stem weight. Figure 7(H) in the figure represents the effect of calcium nitrate supplementation on disease incidence. It can be seen that compared with plants that were not supplemented with calcium nitrate, the total root length, average root diameter, root volume, number of root tips, leaf dry weight, root dry weight, and stem dry weight of buckwheat increased by 20.41%, 20.94%, 21.80%, 70%, 40.45%, 34.25%, and 20.26%, respectively, while the disease incidence decreased by 31.82%.

[0040] Spraying with chelated iron has a significant effect on the photosynthetic pigment content of chlorotic young leaves. (See also:) Figure 8 ,in, Figure 8 (A) in the figure represents the effect of spraying chelated iron on chlorophyll a in chlorotic young leaves. Figure 8 (B) in the figure represents the effect of spraying chelated iron on carotenoids in chlorotic young leaves. It can be seen that compared with the photosynthetic pigments of chlorotic young leaves without chelated iron supplementation, chlorophyll a and carotenoids increased by 51.38% and 36.17%, respectively.

[0041] Simultaneously, this step, as well as subsequent steps S3 and S4, also includes the application of gibberellin: During summer hydroponics, after the cotyledons of buckwheat seedlings unfold, spray the foliage of buckwheat seedlings once with 10 mg / L gibberellin; when buckwheat enters the propagation period, spray the roots of buckwheat exposed to air once with 10 mg / L gibberellin, and simultaneously spray the foliage of buckwheat once with 30 mg / L gibberellin; during winter hydroponics, when transplanting seedlings, use a nutrient solution with a concentration of 1 / 2n for cultivation, and add gibberellin at a ratio of 6.25 mg / L. After 5-10 days, replace the nutrient solution with a nutrient solution with a concentration of n. After 1-2 true leaves have grown, spray the foliage of buckwheat with 20 mg / L gibberellin. After 3-4 true leaves have grown, spray the roots with 10 mg / L gibberellin. When entering the budding stage, spray the foliage of buckwheat once with 30 mg / L gibberellin.

[0042] Spraying gibberellin can significantly improve the seed setting rate of buckwheat during the reproductive period, such as... Figure 9 As shown, where, Figure 9 (A) in the figure represents the effect of gibberellin spraying on the total number of flowers in tartary buckwheat. Figure 9 (B) indicates the effect of gibberellin spraying on grain number. Figure 9 (C) in the figure represents the effect of gibberellin spraying on the number of dead flowers. Figure 9 (D) in the figure represents the effect of gibberellin spraying on the number of effective grains. Compared with tartary buckwheat that was not sprayed with gibberellin, the total number of flowers, the number of grains, the number of dead flowers, and the number of effective grains increased by 33.92%, 65.32%, 40.67%, and 101.87%, respectively.

[0043] S3, vegetative growth period: reduce the amount of nutrient solution added so that at least one-third of the buckwheat roots are exposed to the air between the liquid surface and the foam board; After entering the vegetative growth stage, considering the oxygen demand of the buckwheat roots, this embodiment achieves this by reducing the amount of nutrient solution added, so that some of the buckwheat roots are exposed to the air, thus preventing the buckwheat roots from rotting.

[0044] S4. Reproduction period: From the budding stage to the grain-filling stage, the nutrient solution concentration and light intensity are increased sequentially in each cycle.

[0045] The procedure for increasing nutrient solution concentration according to the cycle is as follows: Based on the nutrient solution concentration during the vegetative growth period, the concentration is increased to 1.1 times during the budding stage, 1.2 times during the full bloom stage, 1.3 times during the early grain filling stage, 1.4 times during the early to mid-grain filling stage, 1.5 times during the mid-grain filling stage, and 1.6 times during the late grain filling stage to the end of the growth period. The procedure for increasing light intensity according to the cycle is as follows: Based on the baseline intensity, the light intensity is increased by 5% from the 5 true leaves stage to the budding stage, by another 5% during the full bloom stage, and by another 5% during the early grain filling stage to the end of the growth period.

[0046] During this period, increasing nutrient solution and light is mainly to improve the fruit setting rate. For example... Figure 10 As shown, compared with buckwheat cultured at the baseline nutrient solution concentration and light intensity, increasing only the nutrient solution concentration, increasing only the light intensity, and simultaneously increasing both the nutrient solution concentration and light intensity increased the seed setting rate by 50.98%, 30.69%, and 100.99%, respectively. It should be understood that this application is not limited to the examples described above, and various modifications and changes can be made without departing from its scope. The true scope is indicated by this application.

Claims

1. A hydroponic method for the entire growth period of buckwheat, characterized in that, The buckwheat is cultivated using a hydroponic system covering the entire growth period, which includes: A hydroponic tray for germinating buckwheat seeds, wherein the hydroponic tray is provided with water-absorbing material and the top of the hydroponic tray is covered with a film; A container for transplanting seedlings, the container having a variable diameter with its upper diameter being larger than its lower diameter, the container having a foam board inside, the foam board having at least one through slit, and the diameter of the foam board being between the upper diameter and the lower diameter of the container; A light panel for providing illumination, the light panel being disposed on a culture rack, and the container being disposed at the lower part of the culture rack; The hydroponic method includes the following steps: S1. Germination: Take buckwheat seeds, disinfect, wash and soak them, then germinate them in a hydroponic tray. Specifically, disinfect the buckwheat seeds with 1% sodium hypochlorite, wash them with water after disinfection, soak them in water for 6-8 hours, and remove the buckwheat seeds floating on the surface. Thoroughly moisten the absorbent material in the hydroponic tray with water, then place the soaked buckwheat seeds on the absorbent material, control the temperature at 20-23℃, and cover the hydroponic tray with a film. After the main root of the buckwheat seeds has grown, apply 2000-5000 lx of light to the hydroponic tray and continue to grow for 3-6 days. S2. Transplanting and planting: Add nutrient solution of concentration n to the container, take the germinated buckwheat seedlings and plant them in the cracks of the foam board and place them in the container, ensuring that the foam board is floating, and place the container in a ventilated place; apply the reference intensity of light to the seedlings through the lamp board. S3, vegetative growth period: reduce the amount of nutrient solution added so that at least one-third of the buckwheat roots are exposed to the air between the liquid surface and the foam board; S4. Propagation period: From the budding stage to the grain-filling stage, the nutrient solution concentration and light intensity are increased sequentially in each cycle. Each of the aforementioned through-slits has a groove at the end facing the bottom of the container, the through-slit extends through the groove, and the groove contains a portion of air, allowing a small number of buckwheat roots to be exposed to the air during the seedling stage. The thickness of the foam board is no more than 1 cm, and the length of the through-slit is 4-5 cm. The maximum light intensity provided by the lamp panel is no less than 40,000 lx. The cultivation rack has several layers, and the height of each layer of the cultivation rack is at least 20 cm higher than the height of the buckwheat plant, and each layer of the cultivation rack is equipped with a lamp panel. S2 also includes manual assisted shell removal, wherein the manual shell removal method is to use gauze wrapped around the top of the seedling or stem, and then pull the gauze to assist in shell removal; After transplanting and planting, the process also includes spraying gibberellin: During summer hydroponics, once the cotyledons of the buckwheat seedlings unfold, spray the foliage of the buckwheat seedlings once with 10 mg / L gibberellin; when the buckwheat enters the propagation period, spray the roots of the buckwheat exposed to the air once with 10 mg / L gibberellin, and at the same time spray the foliage of the buckwheat once with 30 mg / L gibberellin; during winter hydroponics, when transplanting and planting, use a nutrient solution with a concentration of 1 / 2n for cultivation, and add gibberellin at a ratio of 6.25 mg / L. After 5-10 days, replace the nutrient solution with a nutrient solution with a concentration of n. After 1-2 true leaves have grown, spray the foliage of the buckwheat with 20 mg / L gibberellin. After 3-4 true leaves have grown, spray the roots with 10 mg / L gibberellin. When the buckwheat enters the budding stage, spray the foliage of the buckwheat once with 30 mg / L gibberellin.

2. The method according to claim 1, characterized in that, When placing the soaked buckwheat seeds on the absorbent material, the spacing between the buckwheat seeds should be 0.6-1 cm. Before the buckwheat seeds root, spray water on the absorbent material periodically for 10-12 hours. After the buckwheat seeds root and come into contact with the absorbent material, keep the absorbent material moist for 8 hours. Then open the film and spray water once horizontally above the hydroponic tray. Then grow in the dark for 10-15 hours. After the growth in the dark is completed, spray water in the hydroponic tray to keep the absorbent material moist, and grow for 3-6 days under light conditions of 2000-5000 lx.

3. The method according to claim 1, characterized in that, In S2, the nutrient solution is Hogland standard nutrient solution, which is prepared and added to the container according to the ratio of mother liquor to water of 1:100; the reference intensity refers to a light intensity of 20000 lx.

4. The method according to claim 1, characterized in that, In S4, the operation of increasing the nutrient solution concentration according to the cycle is as follows: Based on the nutrient solution concentration during the vegetative growth period, the nutrient solution concentration is increased to 1.1 times during the budding stage, 1.2 times during the full bloom stage, 1.3 times during the early grain filling stage, 1.4 times during the early to mid-grain filling stage, 1.5 times during the mid-grain filling stage, and 1.6 times during the late grain filling stage to the end of the growth period. The operation of increasing the light intensity according to the cycle is as follows: Based on the baseline intensity, the light intensity is increased by 5% from the 5 true leaves stage to the budding stage, by another 5% during the full bloom stage, and by another 5% during the early grain filling stage to the end of the growth period.

5. The method according to claim 1, characterized in that, After transplanting and planting, the steps also include spraying calcium nitrate and chelated iron: when precipitation occurs in the nutrient solution, the pH of the nutrient solution is adjusted to 6-7 using calcium hydroxide, and 472 mg / L of calcium nitrate is added to the nutrient solution at the same time, with 25 ml of calcium nitrate added for every 800 ml of nutrient solution. After 5-10 days, the buckwheat is sprayed with the same concentration of calcium nitrate again; when the young leaves of buckwheat lose their green color, chelated iron at a concentration of 0.1 wt% is sprayed on the leaves.

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