A method of growing a leafy vegetable

Abstract

The application provides a leafy vegetable plant cultivation method, comprising the following steps: providing seedlings of target leafy vegetable plants; cultivating the seedlings of the target leafy vegetable plants under preset cultivation conditions to obtain target leafy vegetable plant plants; wherein the preset cultivation conditions comprise: during the cultivation of the seedlings of the target leafy vegetable plants, using an LED artificial light source as an irradiation light source to irradiate the target leafy vegetables, the LED artificial light source comprises mixed light quality formed by red light, green light and blue light, and the light quality ratio of the red light, the green light and the blue light is (6.74-12.15):(1.04-1.46):1. The cultivation method provided by the application can balance the respiration and transpiration of the stomatal conductance of the plant leaves, is simple in process, can greatly reduce the leaf burning rate of the plants, and can effectively promote the growth of the plants and improve the biomass of the plants.

Description

Technical Field

[0001] This application belongs to the field of vegetable cultivation technology, and more specifically, relates to a method for cultivating leafy vegetables. Background Technology

[0002] Leafy vegetables are rich in nutrients and minerals, making them a staple in the fast-food industry. With the increasing demand for vegetables, greenhouse vegetable cultivation, with its safe and efficient production management methods, has been widely adopted in production. Regulating the light environment within greenhouses is an effective way to improve vegetable production efficiency. The light environment includes three aspects: light intensity, light duration, and light quality combination. Leafy vegetables sense different wavelengths of light through different photoreceptors (phytochromes, cryptochromes, and phototropic proteins). Different wavelengths of incident light are absorbed by different photoreceptors, triggering different physiological responses. Therefore, light quality has a significant impact on the growth, development, and morphogenesis of leafy vegetables.

[0003] LED light sources are cold light sources, possessing higher photoelectric conversion efficiency compared to traditional light sources. Using direct current, LED light sources offer advantages such as energy saving, small size, long lifespan, fixed wavelength, and low heat generation. Furthermore, the luminous intensity and light quality can be adjusted, significantly improving the space utilization efficiency of cultivation. Therefore, LED light sources are considered ideal artificial light sources for applications in closed plant factories, tissue culture rooms, and space agriculture.

[0004] In the process of realizing this invention, the inventors discovered at least the following problems in the prior art:

[0005] Under the existing LED artificial light source, leafy vegetables suffer from severe leaf burn, which adversely affects yield and quality, reducing the economic benefits of leafy vegetables.

[0006] Therefore, further research is needed on the cultivation of leafy vegetables to improve the leaf burn problem in leafy vegetables. Summary of the Invention

[0007] In view of this, this application addresses the shortcomings of the prior art by providing a method for cultivating leafy vegetables, which can improve the leaf burn problem of leafy vegetables and enhance their quality.

[0008] In a first aspect, embodiments of this application provide a method for cultivating leafy vegetables, comprising the following steps:

[0009] Provide seedlings of the target leafy vegetable plants;

[0010] Under preset cultivation conditions, the seedlings of the target leafy vegetable are cultivated to obtain the plant of the target leafy vegetable.

[0011] The preset cultivation conditions include: during the cultivation of the seedlings of the target leafy vegetable, irradiation is performed using an LED artificial light source, wherein the LED artificial light source comprises a mixed light quality formed by red light, green light and blue light, and the light quality ratio of red light, green light and blue light is (6.74~12.15):(1.04~1.46):1.

[0012] In some embodiments, when the LED artificial light source illuminates the seedlings of the target leafy vegetable, the seedlings are in a low-density planting and cultivation period.

[0013] In some embodiments, the cultivation method includes at least one of the following features (1) to (4):

[0014] (1) The day and night temperature in the preset culture conditions is (20℃~24℃) / (15~18℃);

[0015] (2) The daytime and nighttime humidity of the preset culture conditions is (55%~65%) / (60%~70%).

[0016] (3) The photoperiod of the preset culture conditions is 16h / 8h;

[0017] (4) The target leafy vegetable includes at least one of lettuce, radish, tomato, cucumber and strawberry.

[0018] In some embodiments, the cultivation method includes at least one of the following features (1) to (2):

[0019] (1) The light source frequency of the LED artificial light source is 50Hz to 60Hz;

[0020] (2) The photosynthetic photon flux density of the LED artificial light source is 160 μmol / (m 2 ·s)~180μmol / (m 2 ·s).

[0021] In some embodiments, the cultivation method includes at least one of the following features (1) to (3):

[0022] (1) The wavelength of the red light is 650nm~670nm;

[0023] (2) The wavelength of the blue light is 440nm~460nm;

[0024] (3) The wavelength of the green light is 510nm~530nm.

[0025] In some embodiments, during the cultivation of seedlings of the target leafy vegetable, the carbon dioxide concentration in the preset cultivation conditions is 600 ppm to 800 ppm.

[0026] In some embodiments, the preset culture conditions further include: cultivating seedlings of the target leafy vegetable using a 4 / 5 dose of Hoagland standard formula nutrient solution.

[0027] In some embodiments, the pH of the nutrient solution is 5.5 to 6.5.

[0028] In some embodiments, the conductivity of the nutrient solution is 1.8 mS / cm to 2 mS / cm.

[0029] In some embodiments, the dissolved oxygen content of the nutrient solution is 5 mg / L to 10 mg / L.

[0030] Compared with the prior art, this application has at least the following beneficial effects:

[0031] This application cultivates seedlings of target leafy vegetables using a mixed light quality of red, green, and blue light, controlling the light quality ratio of red, green, and blue light to be (6.74–12.15):(1.04–1.46):1. On the one hand, under the irradiation of the above-mentioned specific mixed light quality, it is beneficial to induce chlorophyll synthesis in plants, promote light energy absorption, stimulate electron transport, produce ATP and NADPH (reduced coenzyme II), form organic matter, and increase the biomass of leafy vegetables. On the other hand, the specific mixed light quality of this application can increase the stomatal conductance of leafy vegetables, increase the channels for gas exchange between plant leaves and the outside world, thereby increasing the intercellular CO2 concentration, accelerating the absorption and transport of water and nutrients in plant leaves, and achieving a balance between respiration and transpiration in plant leaves, thereby reducing the rate of leaf burn and improving the quality of leafy vegetables.

[0032] In summary, the cultivation method provided in this application is simple in process, can greatly reduce the leaf burn rate of leafy vegetables, and can effectively promote plant growth and increase plant biomass. Attached Figure Description

[0033] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0034] Figure 1 This is a flowchart illustrating the cultivation method for leafy vegetables in this application;

[0035] Figure 2 Image of the lettuce prepared in Example 1 of this application;

[0036] Figure 3Image of the lettuce prepared in Example 5 of this application;

[0037] Figure 4 Image of the lettuce prepared in Example 9 of this application;

[0038] Figure 5 Image of the lettuce prepared for Comparative Example 1. Detailed Implementation

[0039] To better understand the technical solution of this application, the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0040] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0041] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0042] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0043] In this application, the term "seedling" refers to a young plant that has been cultivated.

[0044] In this application, the term "transplanting" refers to moving seedlings from their nursery structure to their future growing location. Specifically, it refers to transplanting vegetable seedlings to the target planting site after they have grown to a certain stage or extent.

[0045] In this application, the term "low-density planting period" refers to the period when the seedlings of the target leafy vegetable have grown to 4-5 true leaves and are fully unfolded.

[0046] Tipburn is a common physiological disorder in leafy vegetable production. Initially, symptoms appear as small, dark spots on new tissue, which gradually merge. Early on, brown or water-soaked spots appear on the edges of young leaves. In later stages, the leaf edges dry out and rot, leaf growth ceases, and the entire leaf margin turns brown and necrotic. Currently, tipburn in leafy vegetables during their growth stage is mainly affected by the following factors: a. increased light intensity and prolonged photoperiod; b. sustained high temperatures; c. high humidity; d. unsuitable airflow; e. nutrient supply. Excessive nitrogen fertilizer easily leads to tipburn, with ammoniacal nitrogen fertilizer causing even more severe symptoms. Tipburn seriously affects the marketability of vegetables, reducing their quality and market value.

[0047] Light-emitting diodes (LEDs), as a new type of artificial light source, have advantages such as emitting monochromatic light, small size, low heat generation, long lifespan, and high energy efficiency, and have become an ideal tool for studying the effects of light on plant growth and development. However, current LED light sources with full spectrum (R:G:B = 1.31:1.59:1), red light, blue light, and red / blue light with different light quality ratios cannot effectively solve the problem of leaf burn in leafy vegetables.

[0048] In view of this, embodiments of this application provide a method for cultivating leafy vegetables, comprising the following steps:

[0049] Provide seedlings of the target leafy vegetable plants;

[0050] Under preset cultivation conditions, seedlings of the target leafy vegetable are cultivated to obtain plants of the target leafy vegetable.

[0051] The preset cultivation conditions include: during the cultivation of the target leafy vegetable seedlings, the seedlings are irradiated with an LED artificial light source. The LED artificial light source includes a mixed light quality composed of red, green and blue light, and the light quality ratio of red, green and blue light is (6.74~12.15):(1.04~1.46):1.

[0052] In the above-mentioned scheme, this application cultivates seedlings of target leafy vegetables using a mixed light quality of red, green, and blue light, and controls the light quality ratio of red, green, and blue light to be (6.74–12.15):(1.04–1.46):1. On the one hand, under the irradiation of the above-mentioned specific mixed light quality, it is beneficial to induce the synthesis of chlorophyll in plants, promote the absorption of light energy, stimulate electron transport, produce ATP and NADPH (reduced coenzyme II), form organic matter, and increase the biomass of leafy vegetables. On the other hand, the specific mixed light quality of this application can improve the stomatal conductance of leafy vegetables, increase the channels for gas exchange between plant leaves and the outside world, thereby increasing the intercellular CO2 concentration, accelerating the absorption and transport of water and nutrients in plant leaves, and achieving a balance between respiration and transpiration in stomatal conductance of plant leaves, thereby reducing the rate of leaf burn and improving the quality of leafy vegetables.

[0053] Therefore, the cultivation method provided in this application is simple in process, can greatly reduce the rate of leaf burn in plants, and can effectively promote plant growth and increase plant biomass.

[0054] It is understandable that different wavelengths of light have different effects on plant growth and development. Normally, plant growth and development occur under the full spectrum of sunlight (a mixture of red, green, and blue light with a light quality ratio of R:G:B = 1.31:1.59:1). However, different light qualities have different effects on photosynthesis, pigment formation, phototropism, and the induction of morphogenesis in plants. The spectral range of photosynthesis is only in the visible light region (380nm–760nm). Red and orange light are mainly absorbed by chlorophyll, promoting chlorophyll formation. Blue-violet light can also be absorbed by chlorophyll and carotenoids; this part of the radiation is usually called physiologically effective radiation. Green light is rarely absorbed and utilized, and is called physiologically ineffective radiation. Generally, plants cannot utilize yellow-green light, only red and blue-violet light. Experiments have shown that red light helps with sugar synthesis in plants, and red light quality can inhibit internode elongation and increase the plant width of leafy vegetables. Blue-violet light aids in plant protein synthesis, and blue light can significantly shorten the internodes of vegetables, promoting their lateral growth. This application's research found that a light quality ratio of (6.74–12.15):(1.04–1.46):1 for red, green, and blue light promotes the absorption of green light by plants, enhancing photosynthesis in deeper leaves and below the canopy, and inducing chlorophyll synthesis. Simultaneously, it also improves stomatal conductance, achieving a balance between respiration and transpiration, thereby reducing leaf burn.

[0055] Light quality refers to the presence of different wavelengths of light in the illumination. The light quality ratio in this application is different from the photon number ratio. The photon number ratio mainly emphasizes the proportion of the intensity and energy of a certain type of light in the light source. The two have different directions of regulation on plant growth. The applicant found through research that simply adjusting the energy and intensity of light cannot improve the photosynthesis of deep and lower leaves of plants or the pore conductance of plant leaves.

[0056] In this application, stomatal conductance refers to the degree of stomata opening in plant leaves. It can be determined by measuring the size of the stomatal opening (stomatal diameter) or the resistance to the transport of carbon dioxide and water vapor between the atmosphere and the internal tissues of the leaf caused by the stomata (stomatal resistance). Stomata are the main channels for gas exchange between plant leaves and the external environment. Gases diffused through stomata include oxygen, carbon dioxide, and water vapor. Plants perform photosynthesis under light, absorbing carbon dioxide through stomata, so the stomata must be open. However, stomatal opening inevitably leads to transpiration. Therefore, it is necessary to control the stomatal conductance of plant leaves within a suitable range to promote plant growth and development.

[0057] In some implementations, the LED artificial light source is white light supplemented with different proportions of red and blue light, resulting in a red-green-blue mixed light quality ratio of (6.74–12.15):(1.04–1.46):1. Specific ratios include 6.74:1.04:1, 7.85:1.15:1, 8.81:1.19:1, 9.87:1.30:1, 10.58:1.35:1, or 12.15:1.46:1. If the proportion of red light is too low, it will inhibit the formation of chlorophyll, carbohydrates, and photosynthetic organs, leading to stunted and thin plants with low chlorophyll content. If the proportion of red light is too high, it will cause excessive vegetative growth, low chlorophyll content, and a higher incidence of leaf burn. If the proportion of green light is too low, it will affect the photosynthesis of the deeper leaves and leaves below the canopy, reducing the formation of organic matrix in the plant. Furthermore, the stomatal conductance of the plant leaves will be lower, leading to a significant increase in leaf burn rate and affecting biomass. Conversely, if the proportion of green light is too high, the stomatal conductance of the plant leaves will be too large, affecting transpiration. Although photosynthesis in the deeper leaves and leaves below the canopy is stronger, it will still affect leaf growth, leading to an increased leaf burn rate.

[0058] The cultivation method of leafy vegetables described in this application is detailed below with reference to the accompanying drawings. Please refer to the attached drawings. Figure 1 It includes the following steps:

[0059] S100, Provide seedlings of the target leafy vegetable plants.

[0060] In some implementations, the target leafy vegetable is a plant cultivated in a semi-artificial or fully artificial environment such as a greenhouse or plant factory. The target leafy vegetable includes, but is not limited to, at least one of lettuce, radish (especially cherry radish), tomato, cucumber, and strawberry.

[0061] In some implementations, step S100 specifically includes:

[0062] S101: Sowing is carried out in a seedling sponge to germinate the seeds of the target leafy vegetable.

[0063] In practical applications, the seeds of the target leafy vegetable can be sown in the germination holes of a water-soaked seedling sponge for germination. In some cases, the seeds of the target leafy vegetable can be subjected to pre-germination treatment, such as irradiation with artificial light. It should be noted that the artificial light source, light source parameters, irradiation conditions, and other growth environment conditions used in the pre-germination process can be the same as or different from the seedling cultivation process described below, and this application does not impose any restrictions.

[0064] In some implementations, the sowing process specifically involves: soaking a seedling sponge in water, sowing one seed of the target leafy vegetable in each seedling hole, covering the seedling tray with a transparent protective cover or film, and placing the seedling tray on a seedling rack.

[0065] S102: During the transplanting period, add 4 / 5 dose of Hogland standard formula nutrient solution (hereinafter referred to as nutrient solution) to the seedling sponge for seedling cultivation to obtain seedlings of the target leafy vegetable.

[0066] In practical applications, after seed germination, seedlings are cultivated using a nutrient solution to provide nutrients and water to the plants. Specifically, after seed germination, some or all of the moisture in the seedling sponge can be drained, such as draining the surface moisture of the seedling sponge, and nutrient solution can be added to the seedling tray. Understandably, the preset time interval, nutrient solution composition, and concentration can be set according to the actual needs of the target leafy vegetable, such as based on the type of target leafy vegetable, and this application does not impose any restrictions here.

[0067] The 1x dose Hogland standard nutrient solution includes: calcium nitrate tetrahydrate 945 mg / L, potassium nitrate 607 mg / L, ammonium dihydrogen phosphate 115 mg / L, magnesium sulfate heptahydrate 493 mg / L, ferrous sulfate heptahydrate 27.8 mg / L, disodium EDTA 37.3 mg / L, boric acid 2.86 mg / L, manganese sulfate 2.13 mg / L, zinc sulfate 0.22 mg / L, sodium molybdate 0.027 mg / L, and copper sulfate 0.08 mg / L. This nutrient solution contains the essential nutrients for leafy vegetables, including calcium, potassium, phosphorus, magnesium, iron, boron, manganese, zinc, sodium, and copper, and has a suitable total salt content, which is beneficial for seedling growth.

[0068] In some embodiments, the pH of the nutrient solution is 5.5–6.5, specifically 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, or 6.5, and of course, other values ​​within the above range are also possible; this application does not impose any limitations on this. Within the above-defined range, it is beneficial for seedlings to absorb the nutrient solution, improve the effective utilization of nutrients in the nutrient solution by seedlings, and ensure the normal activity of the seedling root system.

[0069] In some embodiments, the electrical conductivity (EC) of the nutrient solution is 1.8 mS / cm to 2 mS / cm, specifically 1.8 mS / cm, 1.9 mS / cm, or 2 mS / cm, or other values ​​within the above range. This application does not impose any limitations on this value. The electrical conductivity of the nutrient solution represents the total salt concentration of the nutrient solution. Within the above-defined range, it indicates that the nutrient solution of this application can provide sufficient nutrients for the seedlings.

[0070] In some implementations, during the seedling process, nutrient solution can be replenished based on a preset time interval, such as 30 minutes / 2 hours during the day and no circulation at night. That is, under the illumination of LED artificial light source, nutrient solution is replenished once every 2 hours, and each replenishment time is half an hour.

[0071] In some embodiments, the dissolved oxygen content of the nutrient solution is 5 mg / L to 10 mg / L, specifically 6 mg / L, 7 mg / L, 8 mg / L, or 10 mg / L, or other values ​​within the above range. This application does not impose any limitations on these values. Within the above range, the growth requirements of leafy vegetables can be met.

[0072] S200: Transplant seedlings of the target leafy vegetable into a cultivation room and cultivate them under preset cultivation conditions to allow the seedlings to grow and obtain the target leafy vegetable plants. The preset cultivation conditions include irradiating the seedlings with an LED artificial light source during the seedling cultivation process.

[0073] In some embodiments, in this application, the LED artificial light source is white light with different proportions of red and blue light added to obtain a red-green-blue mixed light quality with a light quality ratio of (6.74~12.15):(1.04~1.46):1, specifically 6.74:

[0074] Contexts such as 1.04:1, 7.85:1.15:1, 8.81:1.19:1, 9.87:1.30:1, 10.58:1.35:1, or 12.15:1.46:1, etc., indicate that if the proportion of red light is too low, it will inhibit the formation of chlorophyll, chemical components, and photosynthetic organs, resulting in stunted and thin plants with low chlorophyll content, leading to a higher rate of leaf burn. If the proportion of red light is too high, it will cause excessive vegetative growth, but the low chlorophyll content will also result in a higher rate of leaf burn. If the proportion of green light is too low, it will affect the photosynthesis of deeper leaves and leaves below the canopy, reducing the formation of organic matrix and decreasing stomatal conductance, significantly increasing the rate of leaf burn and affecting yield. If the proportion of green light is too high, the stomatal conductance of the plant leaves will be too large, affecting the plant's transpiration. Although the photosynthesis of the deeper leaves and the leaves below the canopy is stronger, it will still affect the plant's leaf growth, leading to an increase in the rate of leaf burn.

[0075] In some embodiments, the wavelength of the red light is 650nm to 670nm, specifically 650nm, 653nm, 655nm, 658nm or 670nm, and of course other values ​​within the above range, which are not limited here.

[0076] In some embodiments, the wavelength of blue light is 440nm to 460nm, specifically 440nm, 445nm, 448nm, 450nm, 453nm, 456nm, 458nm or 460nm, and of course other values ​​within the above range, which are not limited herein.

[0077] In some embodiments, the wavelength of the green light is 510nm to 530nm, specifically 510nm, 513nm, 516nm, 520nm, 524nm, 528nm or 530nm, etc., and of course, other values ​​within the above range are also possible, which are not limited here.

[0078] In some embodiments, the light source frequency of the LED artificial light source is 50Hz to 60Hz, specifically 50Hz, 51Hz, 52Hz, 53Hz, 54Hz, 55Hz, 56Hz, 57Hz, 58Hz, 59Hz or 60Hz, and of course other values ​​within the above range are also possible, which are not limited in this application.

[0079] In some implementations, the photosynthetic photon flux density of the LED artificial light source is 160 μmol / (m²). 2 ·s)~180μmol / (m 2 ·s), specifically it can be 160 μmol / (m 2 ·s), 165μmol / (m 2 ·s), 170μmol / (m 2 ·s), 175μmol / (m 2 ·s) or 180μmol / (m 2 The value can be ·s), and of course, it can be other values ​​within the above range, which are not limited herein. Within the above range, it is beneficial to the growth of leafy vegetables. If the photosynthetic photon flux density of the LED artificial light source is less than 160 μmol / (m²), it is beneficial to the growth of leafy vegetables. 2 When the light intensity is low (·s), the transport efficiency and amount of carbohydrates in the leaves decrease. Simultaneously, under the plant's self-regulation mechanism of low light stress, the distribution of photosynthetic products within the plant also changes accordingly. For example, more biomass is allocated to the aboveground parts, resulting in increased plant height, thinner stems, longer and wider leaves, and expanded leaf area to obtain more light energy upwards and outwards. If the photosynthetic photon flux density of the LED light source is higher than 180 μmol / (m²), the plant will be more efficient and efficient in transporting carbohydrates in the leaves. 2 This can cause plant leaves to be easily scorched, resulting in leaf burn, and also reduce the efficiency and utilization of photosynthesis.

[0080] In some embodiments, the preset culture conditions include a daytime temperature of (20℃~24℃) / (15~18℃). Specifically, the daytime temperature can be 20℃, 21℃, 22℃, 23℃, or 24℃, or any other value within that range. This application does not impose any limitations on this. Similarly, the nighttime temperature can be 15℃, 15.5℃, 16℃, 16.5℃, 17℃, 17.5℃, or 18℃, or any other value within that range. This application does not impose any limitations on this.

[0081] In some embodiments, the preset daytime and nighttime humidity of the culture conditions is (55%~65%) / (60%~70%). Specifically, the preset daytime humidity of the culture conditions can be 55%, 58%, 60%, 63%, or 65%, or other values ​​within the above range, which are not limited here. The preset nighttime humidity of the culture conditions can be 60%, 63%, 65%, 68%, or 70%, or other values ​​within the above range, which are not limited here.

[0082] In some embodiments, the preset photocycle for the culture conditions is 16h / 8h. That is, this application uses a 24h cycle, meaning that irradiation is performed for 16 hours within one cycle, and no irradiation is performed for the remaining time.

[0083] In some embodiments, the yield of the target leafy vegetable can be increased by supplementing carbon dioxide in the air. The preset cultivation conditions also include: the carbon dioxide content in the cultivation environment is 600ppm to 800ppm, specifically 600ppm, 630ppm, 650ppm, 680ppm, 700ppm, 750ppm or 800ppm, and of course other values ​​within the above range, which are not limited here.

[0084] In some implementations, nutrient solutions can be added in the cultivation room to cultivate the target leafy vegetables. The nutrient solution includes 4 / 5 of the Hoagland standard formula nutrient solution; that is, seedlings of the target leafy vegetables are cultivated using 4 / 5 of the Hoagland standard formula nutrient solution. Specifically, a 1 / 5 dose Hoagland standard formula nutrient solution includes: calcium nitrate tetrahydrate 945 mg / L, potassium nitrate 607 mg / L, ammonium dihydrogen phosphate 115 mg / L, magnesium sulfate heptahydrate 493 mg / L, ferrous sulfate heptahydrate 27.8 mg / L, disodium EDTA 37.3 mg / L, boric acid 2.86 mg / L, manganese sulfate 2.13 mg / L, zinc sulfate 0.22 mg / L, sodium molybdate 0.027 mg / L, and copper sulfate 0.08 mg / L. The above nutrient solution contains the essential nutrients for leafy vegetables, including calcium, potassium, phosphorus, magnesium, iron, boron, manganese, zinc, sodium, and copper, and has a suitable total salt content, which is beneficial for the suitable growth of seedlings.

[0085] In some embodiments, the pH of the nutrient solution is 5.5–6.5, specifically 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, 6.4, or 6.5, or other values ​​within the above range. This application does not impose any limitations on these values. Within the above-mentioned range, it is beneficial for seedlings to absorb the nutrient solution, improves the effective utilization of nutrients in the nutrient solution by the seedlings, and ensures the normal activity of the seedling root system.

[0086] In some embodiments, the electrical conductivity (EC) of the nutrient solution is 1.8 mS / cm to 2 mS / cm, specifically 1.8 mS / cm, 1.9 mS / cm, or 2 mS / cm, or other values ​​within the above range. This application does not impose any limitations on this value. The electrical conductivity of the nutrient solution represents the total salt concentration of the nutrient solution. Within the above-defined range, it indicates that the nutrient solution of this application can provide sufficient nutrients for the seedlings.

[0087] In some implementations, nutrient solution replenishment can be performed based on preset time intervals. For example, replenishment can be performed every 2 hours from 6:00 to 20:00 every day.

[0088] In some embodiments, the dissolved oxygen content of the nutrient solution is 5 mg / L to 10 mg / L, specifically 6 mg / L, 7 mg / L, 8 mg / L, 9 mg / L, or 10 mg / L, or other values ​​within the above range. This application does not impose any limitations on these values. Within the above range, the growth requirements of leafy vegetables can be met.

[0089] In some embodiments, the composition and form of the culture medium for cultivating the target leafy vegetable in the cultivation chamber can be selected according to the needs of the target leafy vegetable. Specifically, the culture medium in the cultivation chamber can be at least one of a solid culture medium, a liquid culture medium, and a semi-solid culture medium. In some embodiments, based on actual needs, a liquid culture medium (generally water) with similar or different composition from the above-mentioned seedling nutrient solution can be prepared as a preset culture medium for cultivating seedlings. By controlling the preset cultivation conditions in the cultivation chamber, the seedlings are allowed to grow to the target morphology or target growth state under the preset cultivation conditions, thereby achieving the cultivation and harvesting of the target leafy vegetable.

[0090] The embodiments of this application will be further described below with several examples, taking lettuce as an example. However, the embodiments of this application are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of the main claims.

[0091] Example 1

[0092] (1) Sowing: Sowing is carried out in a seedling sponge to allow the lettuce seeds to germinate. The seedling sponge is a water-soaked sponge with multiple seeding holes, in which one lettuce seed is sown.

[0093] Specifically, the seedling sponge can be placed in the seedling tray and covered with a transparent protective cover or film.

[0094] In some cases, artificial light sources are used to irradiate the lettuce seeds in the seedling sponge to promote germination.

[0095] (2) After the seeds germinate, drain some or all of the water from the seedling sponge, add nutrient solution to the sponge, and then plant the seedlings to obtain lettuce seedlings. The seedling nutrient solution includes 4 / 5 dose of Hogland's formula nutrient solution, and 1 dose of Hogland's standard formula nutrient solution includes: calcium nitrate tetrahydrate 945mg / L, potassium nitrate 607mg / L, ammonium dihydrogen phosphate 115mg / L, magnesium sulfate heptahydrate 493mg / L, ferrous sulfate heptahydrate 27.8mg / L, disodium EDTA 37.3mg / L, boric acid 2.86mg / L, manganese sulfate 2.13mg / L, zinc sulfate 0.22mg / L, sodium molybdate 0.027mg / L, and copper sulfate 0.08mg / L.

[0096] (3) When the seedlings in step (2) have grown to 4-5 true leaves and are fully unfolded, select 144 seedlings with uniform growth and transplant them into the planting cover in the cultivation room to ensure that the light intensity received by the lettuce is uniform. Cultivate the lettuce seedlings under the preset cultivation conditions to obtain lettuce plants. The entire cultivation cycle is 35 days.

[0097] The pre-set cultivation conditions include:

[0098] a. Lettuce seedlings are irradiated with artificial light sources, which include a red-green-blue mixed light quality with a light quality ratio of R:G:B = 6.74:1.04:1.

[0099] b. The daytime and nighttime temperatures are 22℃ / 16℃.

[0100] c. The combined photon flux density is 170 μmol / (m 2 ·s).

[0101] d. The photoperiod is 16h / 8h.

[0102] e. The daytime and nighttime humidity is 60% / 65%.

[0103] f. CO2 concentration 700ppm.

[0104] g. The culture nutrient solution includes 4 / 5 doses of Hogland's formula nutrient solution. A 1-dose Hogland standard formula nutrient solution includes: calcium nitrate tetrahydrate 945 mg / L, potassium nitrate 607 mg / L, ammonium dihydrogen phosphate 115 mg / L, magnesium sulfate heptahydrate 493 mg / L, ferrous sulfate heptahydrate 27.8 mg / L, disodium EDTA 37.3 mg / L, boric acid 2.86 mg / L, manganese sulfate 2.13 mg / L, zinc sulfate 0.22 mg / L, sodium molybdate 0.027 mg / L, and copper sulfate 0.08 mg / L. The nutrient solution has a pH of 6.0, a conductivity of 2 mS / cm, and a dissolved oxygen content of 5 mg / L.

[0105] Figure 2The lettuce plants prepared in this embodiment are shown, such as Figure 2 As shown, the lettuce leaves in this embodiment are thick and numerous, the plant is large, and the number of plants with burnt leaves is small.

[0106] Example 2

[0107] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 8.81:1.04:1.

[0108] Example 3

[0109] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 12.15:1.04:1.

[0110] Example 4

[0111] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 6.74:1.19:1.

[0112] Example 5

[0113] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 8.81:1.19:1.

[0114] Figure 3 The lettuce plants prepared in this embodiment are shown, such as Figure 3 As shown, the lettuce leaves in this embodiment are thick and numerous, the plant is large, and the number of plants with burnt leaves is small.

[0115] Example 6

[0116] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 12.15:1.19:1.

[0117] Example 7

[0118] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 6.74:1.46:1.

[0119] Example 8

[0120] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 8.81:1.46:1.

[0121] Example 9

[0122] Unlike Example 1, the artificial light source in step (2) includes a red-green-blue mixed light quality with a light quality ratio of R:G:B = 12.15:1.46:1.

[0123] Figure 4 The lettuce plants prepared in this embodiment are shown, such as Figure 4 As shown, the lettuce leaves in this embodiment are thick and numerous, the plant is large, and the number of plants with burnt leaves is small.

[0124] Comparative Example 1

[0125] Unlike Example 1, the artificial light source in step (2) includes the full spectrum of LEDs with a light quality ratio of R:G:B = 1.31:1.59:1, which is a red-green-blue mixed light quality.

[0126] Figure 5 The lettuce plants prepared in this comparative example are shown, such as Figure 5 As shown, the lettuce in this embodiment has fewer leaves and a smaller plant size.

[0127] Comparative Example 2

[0128] Unlike Example 1, the artificial light source in step (2) includes the full spectrum of LEDs with a light quality ratio of R:G:B = 6.25:1.04:1, which is a red-green-blue mixed light quality.

[0129] Comparative Example 3

[0130] Unlike Example 1, the artificial light source in step (2) includes the full spectrum of LEDs with a light quality ratio of R:G:B = 13.05:1.04:1, which is a red-green-blue mixed light quality.

[0131] Comparative Example 4

[0132] Unlike Example 1, the artificial light source in step (2) includes the full spectrum of LEDs with a light quality ratio of R:G:B = 6.75:1.00:1, which is a red-green-blue mixed light quality.

[0133] Comparative Example 5

[0134] Unlike Example 1, the artificial light source in step (2) includes the full spectrum of LEDs with a light quality ratio of R:G:B = 6.75:1.50:1, which is a red-green-blue mixed light quality.

[0135] Performance testing

[0136] (1) At harvest time 35 days later, the incidence of leaf burn and the leaf burn index were statistically analyzed and compared. Incidence of leaf burn: Visual observation of all tested plants (plants) showed that leaf burn occurred when more than 3 brown lesions appeared on the leaf margins.

[0137] Leaf burn incidence rate = number of diseased plants / total number of plants × 100%.

[0138] Leaf burn index: When more than three brown lesions appear on the edge of the leaves of all tested plants, they are considered diseased leaves.

[0139] Grading standards for burnt lettuce leaves:

[0140] Level 0: Disease-free throughout the entire plant

[0141] Grade 1: Less than 1 / 5 of the plant's leaves are affected.

[0142] Grade 2: 1 / 5 to 2 / 5 of the leaves of the entire plant are affected.

[0143] Grade 3: Disease affects 2 / 5 to 3 / 5 of the leaves of the entire plant.

[0144] Level 4: Disease affects 3 / 5 to 4 / 5 of the entire plant's leaves.

[0145] Level 5: More than 4 / 5 of the plant's leaves are affected.

[0146] Leaf burn index: ∑(number of diseased plants at each level × disease level) × 100 Total number of plants × highest disease level

[0147] (2) The stomatal conductance (mmol / m²) of the plants in each example and comparative example was measured using an FS-3080CPro plant stomatal meter. The measurement was performed on 8 leaves at the outer edge of each plant, and the stomatal conductance (mmol / m²) was measured at 15 locations in different areas of each leaf. 2 ·s), calculate the average stomatal conductance N of each example and comparative example plant. Using the average stomatal conductance H of the LED full spectrum test in comparative example 1 as the evaluation standard, calculate the stomatal conductance percentage X of examples 1 to 9 and comparative examples 2 to 4 compared to the comparative example, where X = (NH) / H*100%.

[0148] The performance test results of the plants obtained from the above embodiments and comparative examples are shown in Table 1 below, where S1 to S9 represent embodiments 1 to 9, and D1 to D5 represent comparative examples 1 to 5.

[0149] Table 1. Test results of lettuce plants from each example and comparative example

[0150]

[0151]

[0152] According to the test data from Examples 1-9, the cultivation method for leafy vegetables provided in this application can induce chlorophyll synthesis, promote light energy absorption, stimulate electron transport, produce ATP and NADPH (reduced coenzyme II), form organic matter, and increase the biomass of leafy vegetables. It can also increase the stomatal conductance of leafy vegetables, increasing the channels for gas exchange between the leaves and the external environment, thereby increasing the intercellular CO2 concentration, accelerating the absorption and transport of water and nutrients in the leaves, and achieving a balance between respiration and transpiration in the stomatal conductance, thus reducing leaf burn rate and improving the quality of leafy vegetables. This provides an effective and reasonable light formula for establishing a high-quality, high-yield, and cost-effective cultivation model for leafy vegetables, and has important reference value for high-quality cultivation of leafy vegetables and supplemental lighting in ordinary cultivation.

[0153] In Comparative Examples 2 and 3, the quality of red light was less than the limits specified in this application, which inhibited the formation of chlorophyll, chemical components, and photosynthetic organs, resulting in stunted and thin plants with lower chlorophyll content. The incidence of leaf burn was still significantly higher than in the plants of Examples 1-9. Conversely, when the quality of red light exceeded the limits specified in this application, it caused excessive vegetative growth, but the chlorophyll content was still lower, and the incidence of leaf burn was still significantly higher than in the plants of Examples 1-9.

[0154] In Comparative Examples 4 and 5, the proportion of green light quality is less than the range defined in this application, which affects the photosynthesis of the deeper layers of leaves and leaves below the canopy, reduces the formation of plant organic matrix, and results in lower stomatal conductance of the plant leaves, leading to a significant increase in leaf burn rate and affecting material yield. Conversely, when the proportion of green light quality is greater than the range defined in this application, the stomatal conductance of the plant leaves is too high, affecting plant transpiration. Although photosynthesis is stronger in the deeper layers of leaves and leaves below the canopy, it still affects leaf growth, leading to an increased leaf burn rate.

[0155] Although this application discloses preferred embodiments as described above, it is not intended to limit the claims. Any person skilled in the art can make several possible changes and modifications without departing from the concept of this application. Therefore, the scope of protection of this application should be determined by the scope defined in the claims of this application.

Claims

1. A method for breeding a leafy vegetable plant, characterized by, The method comprises the following steps: providing seedlings of target leafy vegetable plants; cultivating the seedlings of the target leafy vegetable plants under preset culture conditions to obtain target leafy vegetable plants; wherein the preset culture conditions comprise: during the cultivation of the seedlings of the target leafy vegetable plants, irradiation treatment is performed using an LED artificial light source, the LED artificial light source comprises mixed light quality formed by red light, green light and blue light, and the light quality ratio of the red light, green light and blue light is (6.74-12.15):(1.04-1.46):

1.

2. The breeding method according to claim 1, characterized by, When the LED artificial light source irradiates the seedlings of the target leafy vegetable plants, the seedlings of the target leafy vegetable plants are in a low-density planting cultivation period.

3. The breeding method according to claim 1, characterized by, The cultivation method comprises at least one of the following features (1)-(4): (1) the preset culture conditions have a day / night temperature of (20-24) / (15-18) °C; (2) the preset culture conditions have a day / night humidity of (55-65) / (60-70) %; (3) the preset culture conditions have a photoperiod of 16h / 8h; (4) the target leafy vegetable plants comprise at least one of lettuce, radish, tomato, cucumber and strawberry.

4. The breeding method according to claim 1, characterized by, The cultivation method comprises at least one of the following features (1)-(2): (1) the light source frequency of the LED artificial light source is 50-60 Hz; (2) the photosynthetic photon flux density of the LED artificial light source is 160 μmol / (m 2 ·s) to 180 μmol / (m 2 ·s).

5. The breeding method according to claim 1, characterized by, The cultivation method comprises at least one of the following features (1)-(3): (1) the wavelength of the red light is 650-670 nm; (2) the wavelength of the blue light is 440-460 nm; (3) the wavelength of the green light is 510-530 nm.

6. The breeding method according to claim 1, characterized by, During the cultivation of the seedlings of the target leafy vegetable plants, the carbon dioxide concentration in the preset culture conditions is 600-800 ppm.

7. The breeding method according to claim 1, characterized by, The preset culture conditions further comprise: cultivating the seedlings of the target leafy vegetable plants using a 4 / 5 dose of Hoagland standard formula nutrient solution.

8. The breeding method according to claim 7, characterized by, The pH of the nutrient solution is 5.5-6.

5.

9. The breeding method according to claim 7, characterized by, The conductivity of the nutrient solution is 1.8-2 mS / cm.

10. The breeding method according to claim 7, characterized by, The dissolved oxygen content of the nutrient solution is 5-10 mg / L.

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