Method for improving the microclimate of a daylight greenhouse in cooperation with the height of the cultivation pattern

Abstract

The present application belongs to the technical field of greenhouse environment regulation, and provides a method for improving the microclimate of a sunlight greenhouse by fusing a cultivation mode and plant height, which comprises obtaining greenhouse structure, cultivation space structure, crop growth and external environment parameters; setting different cultivation modes, using Ladybug and Honeybee to establish a greenhouse light environment simulation model; setting different plant height gradients, obtaining soil illumination and solar radiation, establishing a plant height and soil light environment response relationship under different cultivation modes, using elbow point identification method to determine the target plant height; combining different soil space positions and different depth thermal physical parameters to establish a greenhouse thermal environment model, analyzing the soil heat transfer process within the target plant height range, and forming a corresponding plant height optimization regulation scheme. The present application realizes the collaborative regulation of crop cultivation mode and plant height, can effectively utilize solar energy and improve the light and heat environment of the greenhouse, and provides a scientific basis for the microclimate regulation of the sunlight greenhouse and green low-carbon and efficient production.

Description

Technical Field

[0001] This invention belongs to the field of greenhouse environment control technology, specifically involving a method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation mode and plant height. Background Technology

[0002] Solar greenhouses are an important type of facility for winter horticultural production in northern my country. Their thermal environment relies primarily on solar radiation input, insulation from the building envelope, and soil heat storage and release. Different types of solar greenhouses have varying building envelope structures and thermal performance. Some structures primarily serve an insulation function, with limited heat storage capacity, making the winter indoor thermal environment highly dependent on solar radiation and soil heat storage and release. Especially in greenhouses lacking thick heat-storing walls, solar radiation is a crucial source of heat during the day, while the ground soil plays a vital role in heat storage and release. Therefore, fully utilizing solar radiation and improving soil heat storage and release efficiency are important ways to reduce the need for active heating and improve the winter thermal environment of solar greenhouses. However, crop canopies intercept and block solar radiation entering the greenhouse. As plant height increases and canopy coverage strengthens, solar radiation reaching the soil gradually decreases, affecting the soil's daytime heat storage and nighttime heat release. Different cultivation models also have different spatial structures, leading to variations in the response relationship between plant height and soil light environment.

[0003] However, current methods for controlling the light and heat environment in solar greenhouses mainly focus on greenhouse structure, covering materials, and active heating, with insufficient consideration given to the synergistic impact of cultivation patterns and plant height on the soil's light and heat environment. Different cultivation patterns result in varying spatial structures, and changes in plant height alter the canopy shading range and the amount of solar radiation received by the soil, thus affecting the soil's heat storage and release processes. This makes it difficult to simultaneously achieve crop growth and efficient solar energy utilization. Therefore, there is an urgent need for a method to synergistically control cultivation patterns and plant height for green, low-carbon, and efficient production in solar greenhouses. This method involves constructing greenhouse light environment simulation models under different cultivation patterns, analyzing the response relationship between different plant heights and the soil light environment, and determining the optimal plant height that balances crop growth, soil heat storage and release, and the greenhouse's light and heat environment. This would reduce the need for active heating and achieve green, low-carbon, and intelligent control of greenhouse production. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, this invention proposes a method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation models and plant height, comprising the following steps: S1. Obtain basic greenhouse parameters; S2. Set at least two different cultivation modes and obtain the crop cultivation parameters corresponding to each cultivation mode; S3. Based on the basic parameters of the greenhouse and the crop cultivation parameters, use Ladybug and Honeybee to establish a greenhouse light environment simulation model under each cultivation mode. S4. By changing the plant height in the greenhouse light environment simulation model under various cultivation modes, soil light environment parameters under different plant height conditions are obtained. S5. Establish the relationship between plant height and soil light environment response under various cultivation modes based on soil light environment parameters; S6. Curve fitting was performed on the relationship between plant height and soil light environment response to obtain response curves. Elbow point identification method was used to determine the turning points in each response curve. The plant height corresponding to the turning point was determined as the target plant height under each cultivation mode. S7. Obtain soil thermal properties parameters corresponding to different soil spatial locations and soil depths for each cultivation mode, establish a greenhouse thermal environment model, and use the greenhouse thermal environment model to simulate the soil heat transfer process within the target plant height range to obtain soil thermal environment parameters. S8. Verify the soil heat storage and release effects corresponding to the target plant height based on soil thermal environment parameters, and evaluate the degree of coordination between solar radiation utilization and soil heat storage and release processes. S9. Based on the evaluation results of the degree of coordination, determine the final plant height and plant height control scheme suitable for each cultivation mode.

[0005] Preferably, the basic parameters of the greenhouse include greenhouse structural parameters, enclosure structural parameters, and external environmental parameters; crop cultivation parameters include cultivation space structural parameters, crop growth characteristic parameters, and soil spatial structural parameters; soil light environment parameters include soil illuminance, solar irradiance, cumulative solar radiation, solar radiation per unit area, and solar radiation at different time periods; soil thermal property parameters include soil thermal conductivity, volumetric heat capacity, density, specific heat capacity, moisture content, and porosity; and soil thermal environment parameters include soil surface heat flow, soil internal heat flow, soil heat storage during the day, soil heat release at night, and soil temperature change parameters.

[0006] Preferably, in S2, different cultivation modes are formed by changing the cultivation space structure parameters and soil space structure parameters.

[0007] Preferably, in S3, the light environment simulation boundary conditions are set according to the greenhouse's geographical location, greenhouse structural dimensions, simulation date, solar radiation conditions, greenhouse enclosure structural parameters, cultivation space structural parameters, and crop canopy parameters.

[0008] Preferably, in S6, the elbow point identification method is used to identify the location where the trend of soil light environment parameters changes significantly during the increase of plant height, and to determine the plant height corresponding to the location as the target plant height under the corresponding cultivation mode. The elbow point identification method includes one or more of the following: curvature method, slope change method, derivative method, Kneedle algorithm, and identification method based on fitting curve turning feature; the target plant height represents the key height at which the soil light and heat input changes from the early rapid decay stage to the later slow decay stage as the plant height increases.

[0009] Preferably, the greenhouse thermal environment model in S7 adopts the DO radiation model.

[0010] Preferably, when the amount of solar radiation received by the soil under the target plant height condition can meet the soil heat storage requirements during the day, and the soil heat storage during the day and the soil heat release at night are kept within the preset range, the target plant height is determined as the final plant height suitable for the corresponding cultivation mode.

[0011] Preferably, the plant height control scheme refers to using methods such as pruning, trellising, topping, or other control measures to prevent the plant canopy from growing too tall, which would significantly reduce the amount of sunlight received by the soil and the actual heat storage capacity of the soil. This keeps the plant height within a suitable range and reduces soil shading caused by the continuous increase in plant canopy height.

[0012] Preferably, crop growth characteristic parameters include plant height, canopy width, canopy thickness, leaf area, leaf area index, canopy coverage, and planting density.

[0013] Compared with the prior art, the present invention has the following outstanding advantages: (1) A novel method is proposed to improve the microclimate of a solar greenhouse by integrating cultivation mode and plant height. Based on the differences in cultivation space and soil space structure under different cultivation modes, and combined with the growth characteristics of plants, the degree of canopy shading is changed by adjusting the height of crop plants, so that crop growth and soil light reception are coordinated. This not only meets the needs of crop growth, but also greatly improves the efficiency of solar energy utilization and improves the light and heat environment of the greenhouse.

[0014] (2) A method is proposed to cleverly determine the elbow point plant height by establishing the relationship between plant height and soil light environment response. Multiple plant heights are set for different cultivation modes. Soil illuminance and solar irradiance in soil areas such as ridges and furrows are obtained using Ladybug and Honeybee. Fitting curves of soil illuminance, solar irradiance and plant height are established, and the target plant height is determined by elbow point identification method.

[0015] (3) It has green, low-carbon, and high-efficiency production characteristics and good applicability for promotion. This invention does not limit the specific cultivation mode, crop type, or plant height. It can establish corresponding light environment response relationships and thermal environment analysis models based on different greenhouse structures, cultivation spaces, crop growth characteristics, and soil thermophysical parameters to determine the appropriate plant height. It is applicable to the light and heat environment control of different types of solar greenhouses.

[0016] (4) A new strategy for improving the light and heat environment of solar greenhouses in winter is provided. Based on the analysis results of soil light environment under different cultivation modes and soil heat storage and release performance, the appropriate plant height is determined, and plant height is controlled by pruning, trellising, and topping to reduce the shading of soil by excessively tall canopies and improve the efficiency of soil solar energy storage and release, thus providing a new low-carbon strategy for improving the light and heat environment of solar greenhouses in winter. Attached Figure Description

[0017] Figure 1 This is a flowchart of the method for synergistically improving the microclimate of a solar greenhouse according to Embodiment 1 of the present invention; Figure 2 This is a three-dimensional light environment modeling diagram of a greenhouse according to Embodiment 1 of the present invention; Figure 3 This is a diagram showing the relationship between plant height and soil illuminance in Embodiments 1 and 2 of the present invention; Figure 4 The above are plant height-solar irradiance diagrams for Embodiments 1 and 2 of the present invention. Figure 5 This is the excavation site of the soil profile structure in Embodiment 1 of the present invention; Figure 6 This is a temperature comparison chart of Embodiment 3 of the present invention; Figure 7 This is a diagram showing the greenhouse environment test phenomenon with a plant height of 80 cm in Embodiment 3 of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0019] Example 1

[0020] Embodiment 1 of this invention proposes a method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation methods and plant height, specifically including the following steps: This embodiment uses strawberry and tomato as the experimental crops, and a ridge cultivation model with a center-to-center distance of 1.5 m as the basis. Through a combination of actual greenhouse cultivation experiments, numerical simulation of light and heat environments, the relationship between plant height and soil light environment response under different cultivation models was established. The elbow point identification method was used to determine the target plant height. Furthermore, a greenhouse heat environment model considering the thermal properties of soil stratification was used to verify the soil heat storage and release capacity corresponding to the target plant height. Figure 1 As shown.

[0021] S1. Obtain the basic parameters of the greenhouse, including greenhouse structural parameters, enclosure structure parameters and external environmental parameters.

[0022] The greenhouse structural parameters include greenhouse length, span, ridge height, wall structure, roof structure, greenhouse space dimensions, and geographical location; the enclosure structural parameters include plastic film, flexible covering materials, insulation materials, and their thermal properties such as density, thermal conductivity, and specific heat capacity; and the external environmental parameters include outdoor solar radiation, air temperature, air humidity, and other environmental boundary conditions.

[0023] In this first embodiment, no active heating equipment is installed inside the greenhouse. The winter thermal environment is mainly maintained by solar radiation input, soil heat storage and release, and insulation of the enclosure structure. Therefore, the soil's ability to acquire solar radiation and its heat storage and release process are important aspects of the greenhouse thermal environment analysis.

[0024] S2. Through actual greenhouse cultivation experiments, set up at least two different cultivation modes and obtain the crop cultivation parameters corresponding to each cultivation mode. The crop cultivation parameters include cultivation space structure parameters, crop growth characteristic parameters and soil space structure parameters. The crop growth characteristic parameters include plant height, canopy width, canopy thickness, leaf area, leaf area index, canopy coverage and cultivation density, etc.

[0025] The cultivation pattern is formed by changing the cultivation space structure parameters and soil space structure parameters. The cultivation space structure parameters include row spacing, plant spacing, ridge spacing, ridge height, ridge width, ridge furrow width, cultivation density, cultivation area size, and cultivation direction.

[0026] The actual greenhouse cultivation experiment refers to obtaining the spatial structure parameters of the ridge area and furrow area under different cultivation modes, and obtaining the soil temperature and soil thermophysical parameters at different spatial locations, in order to characterize the soil environmental characteristics of the cultivation area and non-cultivation area corresponding to different cultivation modes.

[0027] This first embodiment is based on ridge cultivation, establishing a 1.5 m ridge center-to-center spacing cultivation model. The specific parameters of this cultivation model are: ridge center-to-center spacing of 1.5 m, row spacing of 0.4 m, ridge height of 0.2 m, upper ridge width of 0.6 m, and lower ridge width of 0.8 m. Based on the above cultivation model, the spatial structure of the cultivation and non-cultivation areas within the greenhouse is established. The greenhouse ground soil is divided into ridge soil areas and furrow soil areas, and the soil environmental characteristics of different spatial locations are characterized respectively.

[0028] S3. Based on the greenhouse basic parameters and crop cultivation parameters, use Ladybug and Honeybee to establish greenhouse light environment simulation models under various cultivation modes, and set light environment simulation boundary conditions according to greenhouse geographical location, greenhouse structural dimensions, simulation date, solar radiation conditions, greenhouse enclosure structural parameters, cultivation space structural parameters and crop canopy parameters.

[0029] Based on the greenhouse structural parameters and external environmental parameters obtained in S1, and the crop cultivation parameters and cultivation space structural parameters obtained in S2, a three-dimensional geometric model of the greenhouse was established on the Rhino / Grasshopper platform. A greenhouse light environment simulation model was then built using Ladybug and Honeybee. Figure 2 As shown. Figure 2 The circles in the diagram represent different directions, the green cuboids represent plants, and the small balls represent the sun. The small balls in different positions represent the sun's trajectory throughout the day.

[0030] Specifically, a geometric model was built using Rhinoceros 3D software. The model was created based on actual measurements of the greenhouse dimensions, crop layout, and height. A soil model with a depth of 1 m was built beneath the greenhouse, along with a soil model of the raised beds in the cultivation area. Plant modeling was simplified based on the principles of equivalent shading area and identical volume. The Ladybug plugin in the Grasshopper platform was used to simulate and analyze the greenhouse's light intensity. The Ladybug climate analysis plugin can import standard EnergyPlus Weather files (.EPW) into Grasshopper to collect regional climate data.

[0031] In this embodiment, a strawberry-tomato canopy model was established based on actual cultivation conditions, with plant height as the main adjustable growth characteristic parameter. By changing the plant height parameter while keeping other greenhouse structure and cultivation space parameters constant, the influence of plant height changes on the soil's ability to capture solar radiation was analyzed. The winter solstice was selected as a typical low solar altitude angle condition in winter, and the period of daylight exposure from 9:00 to 15:00 was selected as the main analysis period to obtain the solar radiation distribution in the greenhouse soil area under different plant height conditions.

[0032] S4. Set multiple different plant heights for each cultivation mode. By changing the plant height in the greenhouse light environment simulation model, obtain soil light environment parameters under different plant height conditions. Soil light environment parameters include soil illuminance, solar irradiance, cumulative solar radiation, solar radiation per unit area, and solar radiation at different time periods.

[0033] For different cultivation modes established in S2, multiple plant heights were set. By changing the plant height parameters in the light environment simulation model, the shading effect of the crop canopy on solar radiation in the greenhouse soil under different plant height conditions was simulated. In this embodiment, eight plant height gradients were set: 30 cm, 50 cm, 70 cm, 90 cm, 110 cm, 130 cm, 150 cm, and 170 cm.

[0034] Soil light environment parameters were extracted for each plant height, and the average values ​​during the effective lighting period were calculated. Soil illuminance in the greenhouse soil area was extracted using the HB Point-In-Time Grid-Based battery pack on the Grasshopper platform in Rhino software; solar irradiance in the greenhouse soil area was extracted using the HB Cumulative Radiation battery pack; and the average solar radiation during the effective lighting period was directly calculated using the LB Analysis Period battery pack. The soil areas included the ridge soil area, the furrow soil area, and other soil areas.

[0035] Using the above method, a dataset of "plant height - soil light environment parameters" was obtained.

[0036] S5. Based on the "plant height - soil light environment parameters" dataset, establish the relationship between plant height and soil light environment response under various cultivation modes.

[0037] The results of the "plant height-soil light environment parameters" dataset in Example 1 show that as the plant height increases from 30cm to 170cm, the solar radiation received by the greenhouse soil generally shows a continuous downward trend. This indicates that as the plant height increases, the interception effect of the strawberry-tomato canopy on the solar radiation entering the greenhouse gradually increases, while the solar radiation reaching the soil surface gradually decreases.

[0038] For the cultivation pattern with a center-to-center spacing of 1.5 m, when the plant height increased from 30 cm to 170 cm, the average soil illuminance decreased from 15337 Lux to 9211 Lux, a decrease of 40.0%; the average solar irradiance decreased from 169 W / m² to 100 W / m², a decrease of 40.8%.

[0039] Further analysis showed that when the plant height increased from 30 cm to 70 cm, both the average soil illuminance and the average solar irradiance decreased by about 23%, which was the main stage of rapid decline in soil light and heat input. When the plant height continued to increase to over 90 cm, the soil light environment still declined, but the rate of decline gradually decreased.

[0040] S6. Curve fitting is performed on the relationship between plant height and soil light environment response to obtain plant height and soil light environment response curves under each cultivation mode. An elbow point identification method is used to determine the inflection points in each response curve, and the plant height corresponding to the inflection points is determined as the target plant height for each cultivation mode. The elbow point identification method is used to identify locations where the trend of soil light environment parameters changes significantly during the increase of plant height, and the plant height corresponding to these locations is determined as the target plant height for the corresponding cultivation mode. The elbow point identification method includes one or more of the following: curvature method, slope change method, derivative method, Kneedle algorithm, and inflection feature identification method based on fitted curves.

[0041] In order to quantitatively identify the location where the soil light and heat input changes from rapid to slow decay during the process of increasing plant height, plant height was used as the independent variable and average soil illuminance or average solar irradiance was used as the dependent variable. The simulation results under different plant height conditions were fitted with exponential decay curves, as shown in Equation (1).

[0042] (1) In equation (1), y ( h ( ) represents plant height h The light environment response variables under the given conditions can be represented by average soil illuminance or average solar irradiance, respectively. h Plant height, in cm; h 0 represents the initial plant height, which is taken in this embodiment. h 0 = 30 cm; p This represents the progressive value when the soil light environment tends to stabilize after the plant height continues to increase; k The attenuation coefficient is denoted as . The model parameters are estimated using the least squares method, i.e., determined by the minimum sum of squared residuals, as shown in equation (2).

[0043] (2) In equation (6), y i The simulated light environment response values ​​are as follows: y p These are the fitted values ​​for the corresponding plant height. n The sample size is given. The model fit is expressed using R1. 2 The RMSE was evaluated. The R value corresponding to soil illuminance at a center-to-center distance of 1.5 m was...2 With RMSE values ​​of 0.994 and 146.64 Lux respectively, the corresponding R value for solar irradiance at a ridge center-to-center distance of 1.5 m is... 2 The RMSE values ​​were 0.997 and 1.18 W / m², respectively.

[0044] After obtaining the continuous fitted curve, the Kneedle elbow identification algorithm is used to determine the curve inflection point. Since soil illuminance and solar irradiance decrease monotonically with increasing plant height, the plant height and fitted response value are first normalized, as shown in equations (3) and (4).

[0045] (3) (4) In equations (3) and (4), x ( h (This refers to the normalized plant height.) z ( h () represents the normalized ambient light response value; h min and h max These represent the minimum and maximum plant heights within the study area, respectively. After normalization, the starting and ending points of the curves correspond to (0,1) and (1,0), respectively. If the soil light environment decreases linearly with plant height, the normalized curve should be close to the straight line connecting the starting and ending points, as shown in equation (5).

[0046] (5) The degree of deviation of the actual fitted curve from the line connecting the point can be represented by the distance from the point to the line, as shown in equation (6).

[0047] (6) In equation (6), when d ( h When the value reaches its maximum, it indicates that the deviation of the fitted curve from the linear descent baseline is most significant at that point, which is the location where the attenuation of light and heat input to the ground soil is most prominent.

[0048] Calculation results show that, under the condition of a 1.5 m ridge center-to-center distance, the elbow point of the average soil illuminance response curve is located at 87.17 cm, and the elbow point of the average solar irradiance response curve is located at 87.21 cm. The elbow point heights obtained for the two light environment indices are basically consistent. Figure 3 and 4 As shown.

[0049] When the center-to-center distance of the ridges is 1.5 m, the elbows corresponding to the average soil illuminance and average solar irradiance are 87.17 cm and 87.21 cm, respectively. Therefore, in this embodiment, 87 cm is determined as the initial value of the target plant height under the 1.5 m center-to-center distance cultivation mode.

[0050] The target plant height represents the key height position at which soil light and heat input transitions from a rapid decline phase in the early stage to a slow decline phase as plant height increases.

[0051] S7. Obtain soil thermal properties corresponding to different soil spatial locations and soil depths for each cultivation mode. Use these as the basic parameters for greenhouse thermal environment analysis. Based on the soil thermal properties, greenhouse basic parameters, and target plant height, establish a greenhouse thermal environment model. Use the greenhouse thermal environment model to simulate the soil heat transfer process at the target plant height and obtain soil thermal environment parameters, including soil surface heat flow, soil internal heat flow, daytime soil heat storage, nighttime soil heat release, and soil temperature change parameters. The soil thermal properties are obtained through soil sampling and indoor experiments, including soil thermal conductivity, volumetric heat capacity, density, specific heat capacity, moisture content, and porosity, and are obtained separately according to different cultivation modes, different soil spatial locations, and different soil depths.

[0052] The greenhouse thermal environment model adopts the DO radiation model (Discrete Ordinates), which is applicable to most optical radiation problems. It can handle various complex geometries and multiple boundary conditions, and can numerically simulate the radiation conditions in the greenhouse at different times and seasons. It considers the influence of scattering effects on radiation distribution and sets the solar position, radiation intensity, and radiation thermophysical properties of the materials.

[0053] This first embodiment is based on the actual spatial structure characteristics of greenhouse soil ( Figure 5 The soil was divided into four depth zones: 0–10 cm, 10–30 cm, 30–50 cm, and 50–100 cm, and corresponding soil thermal properties parameters were set for each zone. The soil density of the 0–10 cm layer is 1531 kg / m³, the thermal conductivity is 0.5 W / (m·K), and the specific heat capacity is 2365 J / (kg·K); the soil density of the 10–30 cm layer is 1590 kg / m³, the thermal conductivity is 0.9 W / (m·K), and the specific heat capacity is 2283 J / (kg·K); the soil density of the 30–50 cm layer is 1625 kg / m³, the thermal conductivity is 1.4 W / (m·K), and the specific heat capacity is 3013 J / (kg·K); and the soil density of the 50–100 cm layer is 1698 kg / m³, the thermal conductivity is 2.1 W / (m·K), and the specific heat capacity is 2934 J / (kg·K).

[0054] Based on the actual spatial structure of greenhouse soil, the soil areas in the ridges and furrows were spatially divided, and corresponding soil thermal environment attributes were set according to soil parameters at different spatial locations. On this basis, greenhouse structural parameters, enclosure structural parameters, soil thermal properties, external environmental parameters, and soil solar radiation results under different plant heights were used as input parameters for the greenhouse thermal environment model. The model further simulated and analyzed the soil heat transfer process under different plant heights, obtaining soil thermal environment parameters such as soil temperature at different depths, soil surface heat flow, and soil internal heat flow. Based on the change in soil internal heat flow over time, the model calculated the daytime soil heat storage and nighttime soil heat release. Furthermore, the relationship between soil solar radiation input and soil heat transfer at different time periods was analyzed, mainly by extracting and comparing soil solar radiation and soil temperature data to provide a basis for evaluating the relationship between soil solar radiation utilization and soil heat storage and release processes under different cultivation models.

[0055] S8. Verify the soil heat storage and release effects corresponding to the target plant height based on soil thermal environment parameters, and evaluate the degree of coordination between solar radiation utilization and soil heat storage and release processes.

[0056] S9. Based on the evaluation results of the degree of coordination, determine the final plant height and plant height control scheme suitable for each cultivation mode.

[0057] When the amount of solar radiation received by the soil under the target plant height condition can meet the soil heat storage requirements during the day, and the soil heat storage during the day and the soil heat release at night are kept within the preset range, the target plant height is determined as the final plant height suitable for the corresponding cultivation mode.

[0058] The plant height control scheme refers to controlling the height of crop plants so that they can fully utilize solar radiation reaching the soil to store heat before reaching the final plant height. This is achieved through pruning, trellising, topping, or other control methods to prevent the canopy from growing too tall and significantly reducing the amount of sunlight reaching the soil and the actual heat storage capacity of the soil. The goal is to keep the plant height within a suitable range to reduce soil shading caused by the continuous increase in plant canopy height.

[0059] This first embodiment primarily determines the target plant height based on the elbow point of the plant height-soil light environment response curve, and uses soil thermal environment analysis results for auxiliary evaluation, thereby forming a control scheme that matches different cultivation space structures with plant growth height. This first embodiment shows that, under the same greenhouse structure and crop conditions, the cultivation space structure can change the degree to which the plant canopy blocks soil solar radiation, and further affect the response relationship between plant height and soil light environment.

[0060] Example 2

[0061] Embodiment Two of this invention, based on the method described in Embodiment One, modifies the cultivation space structure to further verify the variation pattern of target plant height under different cultivation modes. Embodiment Two uses the same greenhouse structure, crop type, crop canopy parameters, light environment simulation method, simulation date, and analysis period as Embodiment One, only adjusting the center-to-center distance of the rows in the cultivation mode from 1.5 m to 1.8 m. This is to analyze the response relationship between plant height and soil light environment after expanding the inter-row space, and to determine the target plant height that matches the 1.8 m center-to-center distance.

[0062] 1. Establish a cultivation model with a center-to-center spacing of 1.8 m ridges.

[0063] While keeping the greenhouse structure and crop conditions unchanged as described in Example 1, the center-to-center distance between ridges is adjusted from 1.5 m to 1.8 m. In this Example 2, the row spacing remains 0.4 m, the ridge height remains 0.2 m, the upper ridge width remains 0.6 m, and the lower ridge width remains 0.8 m; only the center-to-center distance between adjacent cultivation ridges is changed.

[0064] Based on the above parameters, the spatial structure of the cultivation and non-cultivation areas inside the greenhouse was re-established, forming a greenhouse cultivation spatial structure under a ridge center-to-center distance of 1.8m. By changing the ridge center-to-center distance, the horizontal spacing between crop canopies was altered, thereby changing the shading path and shading range of the plant canopy on the soil solar radiation.

[0065] 2. Establish simulation conditions for the light environment with a center-to-center distance of 1.8 m between ridges.

[0066] Based on the greenhouse light environment simulation model established in Example 1, the cultivation space structure was adjusted to a row center-to-center distance of 1.8 m, while other simulation conditions remained the same. Specifically, the greenhouse structural parameters, greenhouse geographical location, crop type, strawberry-tomato canopy model, solar radiation conditions, simulation date, and effective light-gathering period were all kept consistent with Example 1.

[0067] In this second embodiment, the winter solstice is still selected as the typical low solar altitude angle condition in winter, and 9:00-15:00 is used as the light analysis period. Through the above settings, this allows for a single-factor comparison between this embodiment and the first embodiment, except for the center-to-center distance of the ridges, to analyze the impact of changes in cultivation space structure on the relationship between plant height and soil light environment response.

[0068] 3. Set different plant height gradients.

[0069] For the 1.8 m ridge center-to-center cultivation mode, the same plant height gradient as in Example 1 was set.

[0070] In this second embodiment, eight plant height conditions were set: 30 cm, 50 cm, 70 cm, 90 cm, 110 cm, 130 cm, 150 cm, and 170 cm. Under each plant height condition, the average illuminance and average solar irradiance of the greenhouse soil area were calculated, and soil light environment response data under different plant height conditions were obtained.

[0071] By using the same plant height gradient and evaluation index as in Example 1, the simulation results under different ridge center distances are ensured to be comparable.

[0072] 4. Establish the relationship between plant height and soil light environment response under the condition of 1.8 m ridge center distance.

[0073] Based on the average soil illuminance and average solar irradiance obtained under different plant height conditions, the response relationship between plant height and soil light environment under a ridge center-to-center distance of 1.8m was established.

[0074] The results showed that when the center-to-center distance of the ridges increased to 1.8 m, the space between the plant canopies increased, and the shading effect of the canopies on the soil solar radiation was weakened. However, as the plant height increased, the average soil illuminance and average solar irradiance still showed an overall downward trend.

[0075] This indicates that changes in the cultivation space structure do not alter the overall pattern that increased plant height leads to a decrease in soil light environment, but they do change the specific degree of response of the soil light environment to changes in plant height.

[0076] 5. Fit the response curve under the condition of 1.8 m ridge center distance.

[0077] Plant height was used as the independent variable, and average soil illuminance and average solar irradiance were used as the dependent variables. The same exponential decay model as in Example 1 was used for fitting.

[0078] The fitting results show that, under the condition of 1.8 m ridge center-to-center distance, the fitting determination coefficient R² of the average soil illuminance response curve is 0.988 and the RMSE is 185 Lux; the fitting determination coefficient R² of the average solar irradiance response curve is 0.991 and the RMSE is 2.85 W / m².

[0079] The fitting results above indicate that the exponential decay model can effectively describe the nonlinear response relationship between plant height and soil light environment under a 1.8 m ridge center-to-center distance.

[0080] 6. Determine the target plant height under the condition of 1.8 m ridge center-to-center distance.

[0081] Using the same Kneedle elbow identification algorithm as in Example 1, elbow identification was performed on the response curves of average soil illuminance and average solar irradiance under the condition of 1.8 m ridge center distance.

[0082] First, the plant height and the corresponding fitted light environment response value were normalized. Then, the line connecting the start and end points of the normalized curve was used as the linear descent benchmark. The deviation of each point of the fitted curve from the benchmark was calculated, and the position with the largest deviation was determined as the elbow point of the response curve.

[0083] Calculation results show that, under a ridge center-to-center distance of 1.8 m, the elbows of both the average soil illuminance response curve and the average solar irradiance response curve are located around 96 cm. Figure 3 and Figure 4 As shown.

[0084] Therefore, in this second embodiment, 96 cm is defined as the initial target plant height under the 1.8 m ridge center-to-center spacing cultivation mode. The target plant height represents the critical height position at which the rate of attenuation of soil solar radiation input changes from a relatively fast stage to a relatively slow stage due to the continued increase in plant height under the 1.8 m ridge center-to-center spacing condition.

[0085] 7. Comparison of target plant height under different cultivation space structures.

[0086] The target plant heights obtained in Example 1 and Example 2 were compared.

[0087] The results showed that when the center-to-center distance of the ridges was 1.5 m, the elbows corresponding to the average soil illuminance and average solar irradiance were 87.17 cm and 87.21 cm, respectively. The heights of the two were basically the same, so 87 cm was taken as the initial value of the target plant height under this cultivation model.

[0088] When the center-to-center distance of the ridges increases to 1.8 m, the elbows corresponding to the average soil illuminance and average solar irradiance are both located around 96 cm. Therefore, 96 cm is taken as the initial value of the target plant height under this cultivation mode.

[0089] The comparison results of the two cultivation modes show that as the center-to-center distance of the ridges increases, the horizontal space between crop canopies increases, and the degree of canopy shading on the soil is relatively reduced. Therefore, the key turning point of the soil light environment response curve shifts towards the higher plant height.

[0090] This indicates that the target plant height is not a fixed parameter that corresponds solely to the crop type, but rather a cultivation regulation parameter that matches the cultivation space structure.

[0091] 8. Develop plant height control schemes under different cultivation models.

[0092] Based on the relationship between plant height and soil light environment response obtained in Examples 1 and 2, corresponding reference values ​​for plant height control can be determined for different cultivation space structures. When using a 1.5 m ridge center-to-center spacing cultivation mode, 87 cm can be used as the reference height for plant height control; when using a 1.8 m ridge center-to-center spacing cultivation mode, 96 cm can be used as the reference height for plant height control.

[0093] In actual production, plant height can be adjusted through cultivation measures such as pruning, trellising, and topping, based on crop growth status, cultivation space, and greenhouse environmental conditions, to maintain the plant height near the target height. When the plant height has not yet reached the target height, normal crop growth can be maintained to make full use of the vertical growth space inside the greenhouse; once the plant height reaches or approaches the target height, appropriate plant height control measures can be used to limit the further upward expansion of the canopy, thereby reducing the degree of soil shading caused by the continued increase in canopy height.

[0094] Example 3

[0095] This third embodiment is based on a cultivation model with a 1.5 m center-to-center spacing between rows. While maintaining other greenhouse structural parameters, cultivation conditions, and environmental conditions, two conditions were set: plant heights of 80 cm and 170 cm. The air temperature inside the greenhouse was compared and analyzed. Figure 6 As shown.

[0096] Based on temperature monitoring results under two plant height conditions, the average air temperature inside the greenhouse was higher when the plant height was 80 cm than when the plant height was 170 cm. Throughout the monitoring period, the average greenhouse temperature at a plant height of 80 cm was 2.85 ℃ higher than that at 170 cm, indicating that appropriately reducing plant height can reduce the shading of solar radiation by the crop canopy, allowing more solar radiation to reach the greenhouse soil surface, thereby enhancing the soil heat storage inside the greenhouse. Figure 7 ).

[0097] The above results further demonstrate that plant height not only affects the greenhouse soil light environment but also has a significant impact on greenhouse air temperature. Under the cultivation model with a 1.5 m ridge center-to-center distance, controlling the plant height within a suitable range is beneficial to improving the greenhouse winter thermal environment level, providing a practical temperature response basis for the aforementioned method of determining the target plant height based on the soil light environment elbow point.

[0098] Therefore, by synergistically matching the cultivation space structure with the plant height, a corresponding height control reference scheme can be determined based on the pattern of soil light environment changes with plant height under different cultivation modes. Combined with the analysis results of soil thermal properties and thermal environment, a scientific basis can be provided for the efficient utilization of solar energy in solar greenhouses and the low-carbon control of greenhouse light and heat environment.

Claims

1. A method of improving the microclimate of a solar greenhouse in synergy with the cultivation pattern and the plant height, characterized in that, Includes the following steps: S1. Obtain basic greenhouse parameters; S2. Set at least two different cultivation modes and obtain the crop cultivation parameters corresponding to each cultivation mode; S3. Based on the basic parameters of the greenhouse and the crop cultivation parameters, use Ladybug and Honeybee to establish a greenhouse light environment simulation model under each cultivation mode. S4. By changing the plant height in the greenhouse light environment simulation model under various cultivation modes, soil light environment parameters under different plant height conditions are obtained. S5. Establish the relationship between plant height and soil light environment response under various cultivation modes based on soil light environment parameters; S6. Curve fitting was performed on the relationship between plant height and soil light environment response to obtain response curves. Elbow point identification method was used to determine the turning points in each response curve. The plant height corresponding to the turning point was determined as the target plant height under each cultivation mode. S7. Obtain soil thermal properties parameters corresponding to different soil spatial locations and soil depths for each cultivation mode, establish a greenhouse thermal environment model, and use the greenhouse thermal environment model to simulate the soil heat transfer process within the target plant height range to obtain soil thermal environment parameters. S8. Verify the soil heat storage and release effects corresponding to the target plant height based on soil thermal environment parameters, and evaluate the degree of coordination between solar radiation utilization and soil heat storage and release processes. S9. Based on the evaluation results of the degree of coordination, determine the final plant height and plant height control scheme suitable for each cultivation mode.

2. The method of synergistically improving the microclimate of a solar greenhouse with the fusion cultivation mode and plant height according to claim 1, characterized in that, Greenhouse basic parameters include greenhouse structural parameters, enclosure structural parameters, and external environmental parameters. Crop cultivation parameters include cultivation space structural parameters, crop growth characteristic parameters, and soil spatial structural parameters. Soil light environment parameters include soil illuminance, solar irradiance, cumulative solar radiation, solar radiation per unit area, and solar radiation at different times. Soil thermal properties parameters include soil thermal conductivity, volumetric heat capacity, density, specific heat capacity, moisture content, and porosity. Soil thermal environment parameters include soil surface heat flow, soil internal heat flow, daytime soil heat storage, nighttime soil heat release, and soil temperature change parameters.

3. The method of synergistically improving the microclimate of a solar greenhouse with the fusion cultivation mode and plant height according to claim 2, characterized in that, In S2, different cultivation modes are formed by changing the cultivation space structure parameters and soil space structure parameters.

4. The method of synergic improvement of the microclimate of a solar greenhouse with the fusion cultivation model and the height of the plants according to claim 2, characterized in that, In S3, the light environment simulation boundary conditions are set according to the greenhouse's geographical location, greenhouse structural dimensions, simulation date, solar radiation conditions, greenhouse enclosure structural parameters, cultivation space structural parameters, and crop canopy parameters.

5. The method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation methods and plant height according to claim 2, characterized in that, In S6, the elbow point identification method is used to identify the location where the trend of soil light environment parameters changes significantly during the increase of plant height, and to determine the plant height corresponding to the location as the target plant height under the corresponding cultivation mode. The elbow point identification method includes one or more of the following: curvature method, slope change method, derivative method, Kneedle algorithm, and identification method based on fitting curve turning feature. The target plant height represents the key height at which the soil light and heat input changes from the early rapid decay stage to the later slow decay stage as the plant height increases.

6. The method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation methods and plant height according to claim 5, characterized in that... The Kneedle algorithm is as follows: after obtaining the continuous fitted curve, the Kneedle elbow point identification algorithm is used to determine the curve turning point; since the ground illuminance and solar irradiance show a monotonically decreasing trend with the increase of plant height, the plant height and the fitted response value are normalized as shown in equations (3) and (4). （3） （4） In the formula, x ( h (This refers to the normalized plant height.) z ( h () represents the normalized ambient light response value; h min and h max These represent the minimum and maximum plant heights within the study area, respectively; after normalization, the start and end points of the curves correspond to (0,1) and (1,0), respectively; if the ground light environment decreases linearly with plant height, the normalized curve should be close to the straight line connecting the start and end points, as shown in equation (5): （5） The degree of deviation of the actual fitted curve from the line connecting the points is represented by the distance from the point to the line, as shown in equation (6): （6） In the formula, when d ( h When the value reaches its maximum, it indicates that the deviation of the fitted curve from the linear descent baseline is most significant at that point, which is the location where the attenuation of light and heat input to the ground soil is most prominent.

7. The method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation methods and plant height according to claim 2, characterized in that, The greenhouse thermal environment model in S7 uses the DO radiation model.

8. The method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation methods and plant height according to claim 2, characterized in that, When the amount of solar radiation received by the soil under the target plant height condition can meet the soil heat storage requirements during the day, and the soil heat storage during the day and the soil heat release at night are kept within the preset range, the target plant height is determined as the final plant height suitable for the corresponding cultivation mode.

9. The method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation model and plant height according to claim 8, characterized in that, Plant height control programs refer to methods such as pruning, trellising, topping, or other adjustments to prevent further increases in plant canopy height, which would significantly reduce soil light exposure and actual heat storage. This keeps plant height within a suitable range and reduces soil shading caused by continuous increases in plant canopy height.

10. The method for synergistically improving the microclimate of a solar greenhouse by integrating cultivation methods and plant height according to any one of claims 2-9, characterized in that, Crop growth characteristic parameters include plant height, canopy width, canopy thickness, leaf area, leaf area index, canopy coverage, and planting density.

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