A method and system for rice seedling raising based on plant factories

Abstract

This application relates to the field of rice seedling cultivation technology, and discloses a method and system for rice seedling cultivation based on a plant factory. The method includes: constructing a fully intelligent plant factory seedling cultivation system; placing seedling trays in a storage facility and maintaining their fixed position throughout the entire process; performing dark germination and three-dimensional microenvironment-based synergistic dehumidification; inducing root and crown growth through reverse coupling of water temperature during the greening stage; constructing wind-light synergistic seedling hardening using reconstructed spectra and pneumatic pulses; and removing the finished seedling trays after verifying that the growth indicators are qualified. The system includes: a multi-layer three-dimensional cultivation rack, a seed soaking system, a drying system, a sowing system, a seedling storage system, an air conditioning system, a plant LED lighting system, an irrigation system, a carbon dioxide control system, and a central control system. This invention maintains the physical position of the seedling trays fixed throughout the entire seedling cultivation cycle by using a seedling storage system in conjunction with dynamic switching logic of environmental parameters, thereby eliminating the mechanical costs and manual labor input of transporting seedling trays across regions.

Description

Technical Field

[0001] This invention relates to the field of rice seedling cultivation technology, specifically to a rice seedling cultivation method and system based on a plant factory. Background Technology

[0002] Rice cultivation is rapidly shifting towards a fully mechanized model. Mechanical transplanting has imposed strict quantitative standards on the agronomic traits of seedlings. Qualified machine-transplanted seedlings must have suitable plant height, strong stem mechanical strength, and a tightly coiled root system. To meet the needs of large-scale and intensive production, multi-layer cultivation racks can be constructed in enclosed spaces to overcome the limitations of natural seasons and achieve high-density, year-round continuous production.

[0003] Existing factory-style seedling cultivation typically employs a segmented process management model. Production lines are physically divided into functionally independent work areas. Seed germination takes place in a temperature- and humidity-controlled dark room, while the greening and growth stage is moved to an artificial light seedling room or a multi-span greenhouse. The hardening-off stage before transplanting often requires transporting the seedlings to a hardened outdoor area. Seedling trays need to be sequentially moved between these independent physical spaces. In terms of environmental control, existing facilities largely rely on central air conditioning systems or circulating fans. Control strategies focus on uniformly regulating the temperature and humidity of the entire workshop's macroscopic space. Artificial light sources typically provide a relatively constant spectrum and light intensity to meet the basic photosynthetic needs of the seedlings.

[0004] However, existing rice seedling raising technologies, with their segmented operations, require frequent physical transfers of seedling trays across regions, increasing logistics and machinery costs as well as manual handling. Vibrations during transport can easily damage the substrate structure within the seedling trays, affecting the early anchorage stability of the seedling roots. Furthermore, effective ventilation of the macroscopic space is difficult to penetrate deep into the seedling trays, easily leading to a relatively static, high-humidity boundary layer on the surface of the seedling trays and in the canopy area. This localized moisture accumulation often induces fungal growth and the spread of damping-off disease. Therefore, this invention provides a rice seedling raising method and system based on a plant factory to address the shortcomings of existing technologies. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a rice seedling raising method and system based on plant factories. It solves the problems in existing factory-based seedling raising processes, such as the need for frequent physical transfer of seedling trays across regions, resulting in high logistics costs and easy damage to the substrate structure; the accumulation of heat and humidity in the microenvironment of high-density shelves, which is difficult to dissipate and thus induces diseases; and the excessive growth of seedlings above ground and weak root cohesion under constant superior conditions, which makes it difficult to meet the requirements of mechanized rice transplanting.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] The first aspect of this invention provides a rice seedling raising method based on a plant factory. This method is applied to a fully intelligent environmental control system equipped with a central control system and controlled systems including a seed soaking system, a drying system, a sowing system, a seedling storage system, an air conditioning system, a carbon dioxide control system, a plant LED lighting system, an irrigation system, and a circulating fan system. The method includes the following steps:

[0008] S1, constructing a fully intelligent plant factory seedling raising system;

[0009] S2. Using the seedling storage system, rice seedling trays are transported to a multi-layer three-dimensional cultivation rack, and the static spatial coordinates of the rice seedling trays are established to define an independent control domain, and the physical position is kept fixed throughout the seedling raising process.

[0010] S3. Based on the independent control domain, perform dark germination, turn off the plant LED lighting system and maintain high temperature and high humidity, collect microenvironment data in real time, and when the microenvironment data indicates local humidity accumulation, drive the air conditioning system and the circulating fan system to work together to perform three-dimensional microenvironment dehumidification.

[0011] S4. After germination, turn on the plant LED lighting system and enter the greening growth mode. The real-time substrate moisture content data fed back by the irrigation system is mapped to the water temperature inverse coupling model to generate a dynamic nighttime temperature setpoint to drive the air conditioning system to operate, build the root-crown balance physiological basis, drive the carbon dioxide control system to release carbon dioxide to the air conditioning system outlet, and deliver it to the seedling tray through the circulating fan system.

[0012] S5. Based on the physiological basis of root-crown balance, seedling cultivation is carried out. By reconstructing the short-wavelength spectral output of the plant LED lighting system, wind field disturbance commands are generated to drive the circulating fan system to construct a wind-light synergistic physical acclimatization environment.

[0013] S6. Verify the seedling growth indicators. When they meet the preset standards, generate an outbound command to drive the seedling storage system to remove the finished seedling trays.

[0014] Preferably, in step S3, the step of coordinating the driving air conditioning system and the circulating fan system to perform three-dimensional microenvironment dehumidification further includes:

[0015] The central control system continuously monitors the local relative humidity data distributed on the multi-layer three-dimensional cultivation rack as microenvironment data.

[0016] When the local relative humidity in the microenvironment data continues to be higher than the preset safety threshold or when the irrigation system detects the completion signal of the sprinkler operation, an air conditioning fan linkage dehumidification command is generated.

[0017] Based on the dehumidification command linked to the air conditioner fan, the central control system drives the carbon dioxide control system to block the carbon dioxide supply, simultaneously drives the air conditioning system to switch from constant temperature mode to powerful dehumidification mode to output dry cold air, and forcibly starts the circulating fan system to pump the dry cold air into the shelf to create a gas-liquid coordinated dehumidification flow field.

[0018] Preferably, the circulating fan system includes a fan array disposed between the multi-layer three-dimensional cultivation racks, with the air outlet direction pointing towards the seedling tray area;

[0019] When constructing the gas-liquid synergistic dehumidification flow field, the circulating fan system generates forced convection based on the dry cold air output by the air conditioning system. The forced convection penetrates the dense area of ​​the three-dimensional cultivation rack, destroys the static high-humidity boundary layer on the surface of the rice seedling tray, and brings the accumulated water vapor into the circulation space. The air conditioning system in strong dehumidification mode then condenses and recovers the accumulated water vapor.

[0020] Preferably, in step S4, the step of mapping the real-time substrate moisture content data fed back by the irrigation system to the water temperature inverse coupling model further includes:

[0021] The central control system collects the volumetric water content of the substrate in the seedling tray as real-time substrate water content data through a humidity detection probe.

[0022] At the end of the daily light cycle, it is determined whether the real-time matrix moisture content is below a preset stress response threshold based on the real-time matrix moisture content data.

[0023] When the water content falls below the stress response threshold, it is confirmed that the current period is a dry window, and the difference between the real-time matrix water content data and the stress response threshold is used as an input parameter to import the water temperature inverse coupling model.

[0024] Preferably, in step S4, the water temperature reverse coupling model is used to execute the following computational logic:

[0025] A positive correlation mapping relationship is established between the nighttime temperature setpoint and the real-time matrix moisture content data. The lower the real-time matrix moisture content data, the closer the generated dynamic nighttime temperature setpoint is to the preset induced low temperature lower limit.

[0026] The central control system uses the generated dynamic nighttime temperature setpoint to drive the air conditioning system to adjust the ambient temperature, and cooperates with the low-speed operation of the circulating fan system to ensure low temperature conduction. Through the synergistic effect of the low-temperature environment constructed by the air conditioning system and the real-time substrate moisture content data, which indicates the substrate dryness state, the above-ground growth of seedlings is inhibited and root elongation is induced.

[0027] Preferably, in step S5, the step of generating wind field disturbance commands to drive the circulating fan system to construct a wind-solar synergistic physical acclimatization environment further includes:

[0028] The central control system generates wind field disturbance commands that include preset change frequencies and wind speed ranges.

[0029] The circulating fan system is driven by the wind field disturbance command to perform frequency conversion and speed change or intermittent start and stop actions, and the fans set between the multi-layer three-dimensional cultivation racks are controlled to generate gusts of wind, creating an irregular disturbance wind field between the racks to apply mechanical stimulation to the seedlings.

[0030] Preferably, in step S5, the step of generating pneumatic pulse commands to drive the carbon dioxide control system to construct a wind-solar synergistic physical acclimatization environment further includes:

[0031] The central control system generates pneumatic pulse commands containing preset frequency and pressure parameters.

[0032] The pneumatic pulse command drives the solenoid valve array of the carbon dioxide control system to perform high-frequency intermittent action, controlling the carbon dioxide outlet at the air outlet of the air conditioning system to perform pulsed gas injection. After the pulsed airflow mixes with the air conditioning supply air, the circulating fan of the circulating fan system opens the disturbed wind field to apply mechanical stimulation to the seedlings.

[0033] The construction of the wind-solar synergistic physical acclimatization environment also follows synchronous control logic:

[0034] The effective hardening-off period is determined only when the plant LED lighting system outputs blue or ultraviolet light in response to the spectral reconstruction command and the disturbed wind field is in an active state, ensuring the synchronous superposition of mechanical stimulation and photomorphogenesis signal in the time dimension.

[0035] The central control system performs closed-loop regulation of the wind-solar synergistic physical acclimatization environment based on the comprehensive seedling hardening intensity index, which is jointly determined by light quality factors and aerodynamic factors.

[0036] The seedling hardening comprehensive intensity index is constructed to be positively correlated with the proportion of blue and ultraviolet light quantum flux in the full spectrum, and also positively correlated with the rotational speed change frequency and average wind speed of the circulating fan system.

[0037] A second aspect of the present invention provides a rice seedling raising system based on a plant factory, comprising:

[0038] Multi-layer vertical cultivation racks are set up in the enclosed space of plant factories to accommodate rice seedling trays at high density.

[0039] The seed soaking system, the drying system, and the sowing system are used for the pretreatment and sowing of rice seeds.

[0040] The seedling storage system is used to transport rice seedling trays to the multi-layer three-dimensional cultivation rack;

[0041] The air conditioning system includes air conditioning units and temperature and humidity sensors distributed on the multi-layer three-dimensional cultivation rack, used to regulate the temperature and humidity in the space;

[0042] The circulating fan system includes a fan assembly disposed between the rows of the multi-layer three-dimensional cultivation racks, used to promote airflow circulation inside the racks and deliver the airflow of the carbon dioxide control system to the seedling tray area;

[0043] The plant LED lighting system includes LED light groups installed on top of the multi-layered three-dimensional cultivation rack for providing adjustable spectrum artificial light;

[0044] An irrigation system is used to provide water and nutrient solution to the rice seedling trays and to monitor the substrate moisture content;

[0045] The carbon dioxide control system includes a carbon dioxide gas source and a control valve. The gas outlet of the carbon dioxide control system is located in the air supply channel of the air conditioning system and is used to deliver carbon dioxide gas to the multi-layer three-dimensional cultivation rack area.

[0046] The central control system is used to control the operation of the above systems.

[0047] This invention provides a method and system for rice seedling cultivation based on a plant factory. It has the following beneficial effects:

[0048] 1. This invention, through the seedling storage system and the phased dynamic switching logic of the central control system, maintains the fixed physical position of the seedling trays on the multi-layer three-dimensional cultivation rack throughout the entire seedling cultivation cycle, from sowing to finished product delivery. This changes the traditional factory seedling cultivation production mode that requires multiple transfers between different functional workshops such as germination rooms and greening rooms. It eliminates the mechanical energy consumption and labor costs caused by cross-regional transportation of seedling trays, while avoiding physical damage to the tender root system caused by transportation vibrations, thus maximizing the utilization efficiency of the three-dimensional planting space.

[0049] 2. This invention adopts a deep collaborative strategy of air conditioning dehumidification mode and circulating fan system. When local humidity accumulation is detected, the high-speed forced convection generated by the circulating fan is used to forcefully pump the dry cold air output by the air conditioner into the depth of the shelf, which breaks the static high humidity boundary layer on the surface of the seedling tray and the canopy, and carries the accumulated water vapor into the external circulation space for condensation and recovery by the air conditioning system, thus realizing precise dehumidification and disease prevention and control of the three-dimensional microenvironment.

[0050] 3. This invention establishes a correlation control mechanism between substrate moisture and ambient temperature. When substrate water shortage is detected, the nighttime temperature is automatically reduced. The low temperature and dry environment work together to inhibit excessive elongation of the above-ground parts of the seedlings and promote the root system to grow downward to form a dense root layer. By combining short-wavelength light and the changing wind field generated by the circulating fan, the thickness and toughness of the seedling stems are increased through the synergistic effect of light regulation and wind physical stimulation, ultimately cultivating strong seedlings with suitable plant height, well-developed root system and strong stress resistance. Attached Figure Description

[0051] Figure 1 This is a flowchart of the rice seedling raising process in the plant factory according to the present invention;

[0052] Figure 2 This is a system architecture diagram of the present invention;

[0053] Figure 3 This is a diagram illustrating the air conditioning temperature and humidity control of the present invention.

[0054] Figure 4 This is a flowchart of the carbon dioxide control process of the present invention;

[0055] Figure 5 This is a flowchart of the plant LED lighting control process of the present invention. Detailed Implementation

[0056] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] See attached document Figure 1 - Appendix Figure 5 , Figure 1 This is a flowchart of rice seedling cultivation in a plant factory according to an embodiment of the present invention. Figure 2 This is a system architecture diagram according to an embodiment of the present invention. The present invention provides a rice seedling raising system based on a plant factory, which is set inside a fully enclosed plant factory. The plant factory is equipped with multi-layer three-dimensional cultivation racks for placing seedling trays carrying rice seeds at high density. The plant factory is isolated from the external natural environment by the enclosure structure, forming an independent and controlled cultivation space.

[0058] See attached document Figure 2 The rice seedling raising system communicates with and controls multiple execution subsystems through a central control system. The central control system is used to send control commands to each execution subsystem according to preset rice growth model parameters and to receive environmental data fed back by each sensor.

[0059] The execution subsystem includes a seed soaking system, a drying system, a sowing system, and a seedling storage system. These systems work together to complete seed pretreatment and sowing operations. The seedling storage system is used to automatically transport the sown seedling trays to designated levels of the multi-layer vertical cultivation rack.

[0060] The execution subsystem also includes an air conditioning system for regulating the cultivation environment. The air conditioning system includes upper-level air conditioning units distributed in the upper area of ​​the plant factory and lower-level air conditioning units distributed in the lower area. Temperature and humidity sensors are arranged in the middle area of ​​the multi-layer three-dimensional cultivation rack. The temperature and humidity sensors are used to collect temperature and relative humidity data inside the plant factory in real time and transmit the signals to the central control system. The central control system adjusts the operating power and dehumidification mode of the upper-level and lower-level air conditioning units according to the feedback signals.

[0061] To address the issues of airflow circulation and material transport within the vertical cultivation racks, a transport architecture combining air conditioning and fans is employed. Specifically, the execution subsystem further includes a circulating fan system positioned between each row of multi-layered vertical cultivation racks. This circulating fan system comprises multiple sets of axial or cross-flow fans arranged vertically, with the fan outlets directed towards the seedling trays on both sides, forcibly transporting ambient air blown by the air conditioning system into the high-density rack interior.

[0062] The execution subsystem also includes a carbon dioxide control system responsible for releasing carbon dioxide gas. The output pipe of the carbon dioxide control system is located at the air outlet of the air conditioning system, allowing the released carbon dioxide gas to mix with the airflow output by the air conditioning system. When the air conditioning system is running, the carbon dioxide airflow is driven by the air output by the air conditioning system at the air outlet, causing the carbon dioxide airflow to flow to the area of ​​the circulating fan system, where the circulating fan system delivers the carbon dioxide airflow to the canopy area of ​​the rice seedling tray.

[0063] The execution subsystem also includes a plant LED lighting system, which includes LED light groups installed on the top of each multi-layer three-dimensional cultivation rack and directly above the seedling tray, as well as a light sensor installed below the seedling tray. The LED light groups are used to provide an artificial light source with adjustable quantum flux density and spectral ratio.

[0064] The execution subsystem also includes an irrigation system, which is equipped with nutrient solution delivery pipelines and drip irrigation components to provide water and nutrient solution to the substrate in the seedling tray.

[0065] See attached document Figure 1 Based on the above system architecture, this invention provides a rice seedling raising method based on a plant factory, comprising the following steps:

[0066] S1 is a fully intelligent plant factory seedling raising system, including a central control system, a controlled seed soaking system, a drying system, a sowing system, a seedling storage system, an air conditioning system, a carbon dioxide control system, a plant LED lighting system, and an irrigation system.

[0067] S2 utilizes a seedling storage system to transport rice seedling trays that have completed sowing to designated layers of a multi-layered vertical cultivation rack, and maintains the physical position of the seedling trays fixed throughout the subsequent seedling raising process;

[0068] S3, execute the darkening germination stage control:

[0069] The central control system shuts down the plant LED lighting system. In order to maintain a high temperature and humidity environment, the central control system sets the air conditioning system to operate in heating or constant temperature mode.

[0070] To address the localized high-humidity stagnant layer that easily forms inside the shelving unit, a three-dimensional microenvironment dehumidification control strategy involving fans is implemented.

[0071] Specifically, the central control system monitors local relative humidity data in real time. When the monitoring data indicates that the local humidity accumulation exceeds the safety threshold (e.g., 95%) or when it is detected that the irrigation operation has just ended, the central control system generates a "dehumidification linkage command".

[0072] Based on this dehumidification linkage command, the central control system drives the air conditioning system to switch to dehumidification mode, outputs dry air, forcibly starts the circulating fan system, and increases the fan speed. The air conditioning unit in dehumidification mode reduces the ambient background humidity, while the high-speed circulating fan forcefully blows dry air deep into the shelves, breaking the static high-humidity boundary layer on the surface of the seedling trays, carrying away the accumulated water vapor, and condensing it by the air conditioning system's return air.

[0073] S4, execute green growth stage control: turn on the plant LED lighting system and enter photosynthesis mode;

[0074] The central control system activates the LED lights and calculates the amount of carbon dioxide to be released based on photosynthetic requirements. The system then opens the valve of the carbon dioxide control system, releasing CO2 gas into the air outlet path of the air conditioning system. At this time, the air conditioning system remains on to maintain the set growth temperature, and the circulating fan system operates synchronously, evenly delivering a mixed airflow rich in carbon dioxide and at a suitable temperature to each layer of seedling trays, ensuring a sufficient and evenly distributed supply of carbon source required for photosynthesis.

[0075] At this stage, a water-temperature reverse coupling control strategy based on root-crown balance is introduced. When the substrate moisture content is detected to be below the stress threshold and the dry window period is entered, the central control system adjusts the nighttime temperature setpoint of the air conditioning system and the circulating fan system keeps running at low speed or intermittently to ensure that the low temperature environment can be effectively transferred to the substrate and root area. The dual signals of low temperature and drought are used to induce the roots to grow downward.

[0076] S5, execute the seedling strengthening stage control: adjust the spectral output of the plant LED lighting system, reduce the temperature and humidity parameters set by the air conditioning system, introduce the wind-solar synergistic physical seedling strengthening strategy, and achieve this through the frequency conversion control of the circulating fan system. Specifically, the central control system generates wind field disturbance commands to drive the circulating fan system to perform high-frequency intermittent start-stop or sinusoidal speed changes. This gust effect generated by the fan directly acts on the seedling stems and leaves, causing them to sway physically.

[0077] The physical disturbance is synchronized with the short-wavelength spectrum output by the LED system. Only when the LED lights are turned on and the circulating fan is in disturbance mode is it determined to be an effective seedling hardening period. The mechanical stress generated by the fan promotes the deposition of cellulose in the seedling stems, and the light quality regulation inhibits excessive growth.

[0078] S6. Once the seedling growth indicators reach the preset transplanting standards, the finished seedling trays are removed from the plant factory.

[0079] The environmental control strategies and subsystem linkage logic in each of the above steps will be explained in detail below.

[0080] In this embodiment, step S1 is performed to construct a fully intelligent plant factory seedling raising system. This plant factory seedling raising system is constructed based on a sealed, insulated space, with the main internal structure being a seedling storage system. This seedling storage system adopts a multi-layered, three-dimensional cultivation rack structure to accommodate standard rice seedling trays at high density.

[0081] The central control system is connected to the environmental control and execution unit via fieldbus or industrial Ethernet. The specific arrangement of the environmental control and execution unit is as follows:

[0082] The air conditioning system is arranged in zones along the vertical height of the seedling storage system, divided into an upper return air unit and a lower supply air unit to form air circulation in the three-dimensional space. Temperature and humidity sensors and carbon dioxide sensors are arranged on each layer of the cultivation rack or at a preset key layer height to collect environmental parameters of the local microenvironment.

[0083] To address the issues of airflow circulation and material transport within the vertical cultivation rack, this embodiment incorporates a circulating fan system. This system is positioned between each row of multi-layer vertical cultivation racks and includes multiple sets of axial flow fans or cross-flow fans arranged vertically. The fans' airflow direction is towards the seedling trays on both sides, forcibly transporting the ambient air blown out by the air conditioning system into the high-density rack interior.

[0084] The carbon dioxide control system employs a simplified gas path design. The output pipe of the carbon dioxide control system is located at the air outlet of the air conditioning system, allowing the released carbon dioxide gas to mix with the airflow output by the air conditioning system. When the air conditioning system is running, the carbon dioxide airflow, driven by the air output from the air conditioning system, flows to the circulating fan system area, where the circulating fan system delivers the carbon dioxide airflow to the canopy area of ​​the rice seedling trays.

[0085] The plant LED lighting system is installed on the top inner side of each cultivation rack, directly above the seedling trays. The light source components include independently adjustable red, blue, and ultraviolet light chips to provide photosynthetic quantum flux density (PPFD) and adjust the spectral ratio. The main delivery pipeline of the irrigation system connects to each cultivation rack, with drip or micro-sprinkler irrigation components at the end, and is equipped with a substrate moisture detection probe to monitor the volumetric water content of the substrate in the seedling trays in real time.

[0086] After completing the above system construction and debugging, proceed to step S2. Sow the rice seeds that have undergone seed selection, soaking, disinfection, and pre-germination treatment (or direct dry sowing) into seedling trays containing substrate. Transport the seedling trays to the designated shelf positions of the seedling storage system via automatic conveying equipment or manually.

[0087] After the seedling trays are placed in the storage, their physical position remains fixed throughout the entire seedling cultivation cycle until the seedlings are shipped out, without any physical movement across regions. Switching between seedling cultivation stages is entirely controlled by the central control system, which modifies the operating parameters and logic of the air conditioning system, carbon dioxide system, plant LED lighting system, and irrigation system.

[0088] After step S2 is completed, i.e., the rice seedling trays are placed in the storage, the central control system executes step S3, which is the control of the dark germination stage. During this stage, the central control system sends a shutdown command to the plant LED lighting system, maintaining the photon flux density at 0, thus providing a practically dark germination environment for the seeds. Simultaneously, the central control system sets the operating parameters of the air conditioning system, controlling the overall ambient temperature inside the plant factory within the range of 25℃ to 32℃, and maintaining the relative humidity in the high-humidity range of 80% to 95%. This high-temperature, high-humidity environment aims to promote rapid water absorption by the rice seeds and break their dormancy.

[0089] Given that the seedling storage system employs a multi-layered, densely arranged structure, in a continuously high-humidity environment, the seedling tray area in the lower part of the shelves is prone to forming airflow dead zones. This leads to the local microenvironment remaining saturated with relative humidity for extended periods, potentially inducing mold growth or seedling rot. To further optimize the local microclimate, this embodiment includes a three-dimensional microenvironment dehumidification control strategy in step S3, which links the dehumidification mode of the air conditioning system with the circulating fan system to replace the local high-humidity stagnant layer.

[0090] Specifically, the central control system monitors the local relative humidity data transmitted back by temperature and humidity sensors distributed across each shelf in real time. Once the monitored data meets the preset trigger conditions, the central control system executes a tidal displacement ventilation operation. As a preferred control method, to prevent the equipment from falling into a logic dead zone of frequent starts and stops near the humidity critical point, an interval control algorithm with hysteresis is introduced here.

[0091] See attached document Figure 4 During the tidal displacement ventilation operation, the central control system drives the air conditioning unit to switch from the conventional constant temperature mode to a powerful dehumidification mode with constant temperature compensation, outputting dry air at a suitable temperature to reduce the ambient background humidity. Simultaneously, the central control system forcibly starts the corresponding area's circulating fan system or increases the fan speed. The high-speed circulating fans forcefully blow the dry air generated by the air conditioning system deep into the shelves, using directional convection to break the static high-humidity boundary layer on the surface of the seedling trays and the leaf canopy, and carrying the accumulated water vapor out of the shelf area for condensation and recovery by the air conditioning system in dehumidification mode.

[0092] This control logic can be expressed using state functions. This indicates the solenoid valve corresponding to the circulating fan system in... On / off state at any given time:

[0093] ;

[0094] In the formula, Indicates the current time. This indicates the preset upper limit for relative humidity at startup. This indicates the preset lower limit for stopping the machine due to relative humidity. express Real-time monitored local relative humidity data, Indicates the time when irrigation operations have ended. This indicates the duration of the replacement ventilation window. If the relative humidity is between the upper and lower limits, the equipment operation status of the previous moment is maintained. Through the above control, the physical intervention of the microenvironment of vertical cultivation is achieved by utilizing the synergistic effect of air conditioning and fans. While maintaining a suitable macro-environment for germination, the risk of disease caused by poor local ventilation is avoided. Regarding the switching mechanism between carbon dioxide and compressed air sources, the pipeline connection method, and the specific selection of solenoid valves, those skilled in the art can perform conventional design based on actual working conditions. The specific structure is well-known technology in this field and will not be elaborated upon here.

[0095] See attached document Figure 5 Once the seeds have germinated and entered step S4, the greening growth stage, the central control system adjusts the operating strategies of each subsystem to promote seedling photosynthesis and root system establishment. The central control system sends an activation command to the plant LED lighting system and sets the photosynthetic photon flux density to 200 μmol / m³. 2 ·s to 600μmol / m 2 Within the range of ·s, the photoperiod is set to 12 to 14 hours per day. Based on feedback data from the carbon dioxide sensor, the central control system controls the opening of the carbon dioxide gas source valve, releasing CO2 gas into the air conditioning system's ductwork. At this time, the air conditioning system remains on to maintain the temperature, and the circulating fan system operates synchronously, evenly delivering the temperature-appropriate airflow mixed with carbon dioxide to the seedling canopy, dynamically maintaining the carbon dioxide concentration in the environment between 800 ppm and 1400 ppm to meet the rice seedlings' need for rapid carbohydrate accumulation.

[0096] Regarding basic temperature and humidity control, the central control system instructs the air conditioning system to implement a day-night temperature variation strategy. Specifically, during the daytime, the ambient temperature is maintained between 20°C and 28°C; during the nighttime, the ambient temperature is reduced to between 18°C ​​and 24°C, at which time the relative humidity setting is adjusted to 60% to 80%, which is lower than the dark germination stage, in order to match the enhanced transpiration of the seedlings.

[0097] This embodiment introduces a water-temperature inverse coupling control strategy based on root-crown balance in the later stages of green growth, establishing a deep linkage between the irrigation and air conditioning systems. From a plant physiological perspective, drought in nature is often accompanied by a sharp drop in temperature at night. This combined environmental stress effectively promotes the synthesis of abscisic acid in plants and guides dry matter transfer to the roots. This scheme simulates this microclimate pattern for artificial intervention.

[0098] In practice, the central control system monitors the volumetric moisture content of the substrate in real time using a humidity detection probe inserted into the seedling tray substrate. At the end of each day's light cycle, the system allows the substrate moisture content to drop to a preset stress response threshold. (This threshold corresponds to the near-wilt point of the seedlings; in this embodiment,) The value range is usually set to 30% to 40% of the matrix saturation moisture content, thereby constructing a controlled drying window.

[0099] During this drying window, the air conditioning system dynamically calculates and adjusts the target nighttime temperature based on the degree of decrease in substrate moisture content. The control logic follows a water temperature reverse coupling model:

[0100] ;

[0101] In the formula, This indicates the standard nighttime temperature as normally set. This indicates the lower limit of induced low temperature that can be adjusted (e.g., 15°C). This is the coupling coefficient, and its value is set between 0.3 and 0.8. In practical applications, The specific value can be determined through preliminary tests based on the cold resistance characteristics of rice varieties. Smaller values ​​should be used for indica rice varieties with weaker cold resistance, and larger values ​​should be used for japonica rice varieties with stronger cold resistance.

[0102] Based on the water-temperature inverse coupling model, when the monitored matrix water content... Below the stress response threshold At the same time, the drier the substrate, the lower the nighttime ambient temperature set by the central control system. This control mechanism produces two physiological regulatory effects:

[0103] On the one hand, the moisture deficit signal of the substrate induces the seedling roots to extend rapidly in the longitudinal direction and in all directions to find water sources, promoting the formation of a dense root carpet in the confined space of the three-dimensional cultivation frame.

[0104] On the other hand, the low nighttime temperature effectively reduces the respiration consumption of the above-ground parts of the seedlings, inhibits excessive stem and leaf growth, and forces photosynthetic products (dry matter) to be transferred and accumulated in the roots. The temperature and humidity sensor accuracy calibration and air conditioning frequency conversion control algorithm involved in the above control process can be implemented using existing PID control or fuzzy control techniques by those skilled in the art, and will not be elaborated upon here.

[0105] Before the end of the greening growth stage, in order to enable the cultivated seedlings to adapt to the field environment after transplanting, the central control system executes step S5, namely the seedling strengthening and hardening stage. The system improves the mechanical strength, root vitality and stress resistance of the seedlings by simulating adverse conditions in nature.

[0106] See attached document Figure 3The central control system adjusts the air conditioning system settings to implement cooling and dehumidification strategies, controlling the daytime temperature between 15°C and 25°C and the nighttime temperature between 12°C and 22°C; the relative humidity is set to 50% to 70%; the irrigation system reduces the frequency of water supply, only maintaining the basic physiological water requirements of the seedlings; and promotes the synthesis of abscisic acid (ABA) in the plants through moderate water deficit, thereby improving their cold and drought resistance.

[0107] This embodiment introduces a wind-solar synergistic physical seedling hardening strategy at this stage. This strategy utilizes the spectral adjustment function of the plant LED lighting system and the frequency conversion disturbance function of the circulating fan system to construct a composite seedling hardening mechanism that combines photophysiological inhibition and atmospheric physical stimulation.

[0108] See attached document Figure 5 The central control system adjusts the driving parameters of the LED light group to maintain or increase the photon flux density to 300 μmol / m³. 2 ·s to 500μmol / m 2 Based on the previous method, the spectral composition was altered. Specifically, the proportion of red light was reduced, while the radiant flux of blue light (wavelength around 450nm) and ultraviolet light (UV-A, wavelength 365nm-400nm) was significantly increased. This spectral adjustment, by utilizing the signal transduction functions of cryptochrome and phytochrome, physiologically inhibits excessive elongation of the hypocotyl and internodes in seedlings.

[0109] While adjusting the spectrum, the central control system performs variable speed control on the circulating fan system. Unlike conventional single-speed wind, the system uses a frequency converter to drive the circulating fan to generate a disturbed wind field with alternating speeds across multiple segments. This disturbed wind field simulates the mechanical stimulation of natural gusts on seedlings, forcing them to sway physically, thereby inducing the deposition of cellulose and lignin in the stems, increasing stem diameter and mechanical strength.

[0110] To quantify and precisely control the intensity of the aforementioned physical hardening-off, the central control system is based on a comprehensive hardening-off intensity index. The negative feedback deviation closed-loop regulation is implemented, and the specific control process is as follows: the system pre-sets the target seedling hardening index corresponding to the current rice variety. As a given value, the central control system acquires sensor data in real time and calculates the current actual comprehensive seedling hardening intensity index. As the controlled feedback quantity; the given value Compared with actual value Comparisons can lead to biases, when the actual When the value is lower than the target value, the central control system outputs control commands to increase the short-wavelength light output power of the plant LED lighting system (i.e., increase the light quality factor) and increase the pulse frequency and average output wind speed of the inverter of the circulating fan system (i.e., increase the aerodynamic factor) until the deviation is eliminated and the actual hardening intensity is stabilized within the target range.

[0111] This index is determined by both the light quality factor and the aerodynamic factor, and its calculation model is as follows:

[0112] ;

[0113] In the formula, and These represent the photon flux of blue light and ultraviolet light, respectively. Represents the total photon flux across the entire spectrum; This indicates the frequency of change in the speed of the circulating fan; Indicates the average output wind speed; The synchronization factor is 1 if and only if short-wavelength light (blue light / ultraviolet light) is on and the airflow pulse is active; otherwise, it is 0. and These are transformation weighting coefficients that provide dimensionlessness and order-of-magnitude normalization. They are used to eliminate the dimensional differences and significant magnitude disparities between the optical quality factor and the aerodynamic factor, enabling them to be linearly weighted within the same dimensionless order of magnitude. Weighting coefficients and The specific method for obtaining the data is a conventional engineering experimental approach in this field: for a specific rice variety, an orthogonal experiment is designed with light quality ratio and wind speed frequency as independent variables. The final plant height of the seedlings and the target traits such as stem bending resistance are measured as dependent variables. Then, multiple linear regression analysis is performed using the least squares method, and the specific empirical coefficients corresponding to the variety are obtained by fitting and solving the problem. and .

[0114] Once the pre-set seedling establishment and hardening-off process is completed, and the seedlings are confirmed to have reached the three-leaf-one-heart stage, with well-formed root systems and a plant height meeting mechanized transplanting standards (e.g., 12-18cm), step S6 is executed. The seedling trays are removed from the seedling storage system and prepared for transport to the field for transplanting. The specific drive circuits for the LED spectrum adjustment circuit and the pneumatic solenoid valves involved in the above process are conventional techniques in the field of electronic control. Those skilled in the art can refer to existing technical manuals for implementation, and will not be elaborated upon here.

[0115] The technical solution of the present invention will be further described below with reference to specific embodiments. The specific parameters provided herein are only used to illustrate the preferred implementation of the method of the present invention in a specific application scenario and do not constitute a limitation on the scope of protection of the present invention.

[0116] In this embodiment, a conventional japonica rice variety (such as Nanjing 9108) was selected as the test subject. Rice seeds, after soaking, disinfection, and pre-germination treatment, were sown at a rate of 120 grams (dry seed weight) per tray into standard seedling trays containing seedling substrate. The sown trays were then placed into the seedling storage system of the plant factory, initiating the fully intelligent seedling raising process. The seedling raising cycle was set to 18 days, and the central control system executed environmental parameter adjustments in stages according to preset time-series logic.

[0117] During the dark germination stage from day 1 to day 3, the central control system keeps the plant LED lighting system completely off, the photon flux density is 0, the ambient temperature is set to a constant 30°C, and the target value of the relative humidity is set to 90%. The system activates the air conditioning fan and three-dimensional microenvironment dehumidification logic: when the humidity sensors distributed on the shelves detect that the local humidity exceeds 95%, the air conditioning is triggered to enter the dehumidification mode, and the circulating fan is controlled to run at full speed for 300 seconds to force dry air into the shelves until the local humidity drops back to 85%. This operation effectively prevents the growth of mold in a high-humidity environment.

[0118] During the 4th to 14th day of the greening growth stage, the central control system turned on the plant LED lighting system, setting the photoperiod to 14 hours of light and 10 hours of darkness. For the first 10 days (days 4 to 13), the photon flux density was set to 350 μmol / m³. 2 The system uses a red-blue light spectrum (e.g., red:blue = 4:1), with daytime temperature set at 26℃ and nighttime temperature at 22℃. The ambient carbon dioxide concentration is maintained at 1000±50ppm via feedback regulation from an array of solenoid valves. Starting from day 12, the system implements a reverse coupling control of water and temperature to maintain root-crown balance: the irrigation system reduces watering frequency, and when the substrate volumetric water content drops below 35% (the set stress response threshold), the central control system automatically adjusts the nighttime ambient temperature setpoint from the standard 22℃ to 16℃. This operation utilizes the dual signals of water deficit and low nighttime temperature to inhibit above-ground plant height growth while inducing deeper root development.

[0119] During the seedling hardening-off stage from day 15 to day 18, the central control system adjusted environmental parameters to simulate the natural environment before transplanting, increasing the photonic flux density to 450 μmol / m³. 2The system adjusts the spectral output, increasing the proportion of blue and ultraviolet light radiation to 40% of the total luminous flux. The daytime temperature setting is lowered to 22°C, the nighttime temperature setting to 15°C, and the relative humidity to 60%. During this period of illumination, the system simultaneously activates the wind-solar synergy physical seedling conditioning logic: the system controls the inverter of the circulating fan to perform sinusoidal frequency modulation, causing the output airflow to fluctuate periodically; simultaneously, the carbon dioxide gas source is controlled to smoothly increase and decrease in amplitude using a proportional valve with flow regulation. This variable frequency airflow, mixed with the air supply from the air conditioner, generates a gentle and varied turbulent wind field between the shelves. This physical disturbance, occurring simultaneously with the high proportion of blue light irradiation, promotes the deposition of cellulose in the seedling stems.

[0120] After 18 days of continuous cultivation, the factory inspection showed that the average height of the seedlings was controlled at about 15 cm, the leaf age reached 3.1 leaves, the stem base was wide, flat and thick, and the root system was tightly intertwined and did not fall apart when lifted, which fully met the agronomic standards for mechanized rice transplanting.

[0121] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for raising rice seedlings based on a plant factory, characterized in that, Includes the following steps: S1. Construct a fully intelligent plant factory seedling raising system, which includes a central control system, a seed soaking system, a drying system, a sowing system, a seedling storage system, an air conditioning system, a carbon dioxide control system, a plant LED lighting system, an irrigation system, and a circulating fan system. S2. Using the seedling storage system, rice seedling trays are transported to a multi-layer three-dimensional cultivation rack, and the static spatial coordinates of the rice seedling trays are established to define an independent control domain, and the physical position is kept fixed throughout the seedling raising process. S3. Based on the independent control domain, perform dark germination, turn off the plant LED lighting system and maintain high temperature and high humidity, collect microenvironment data in real time, and when the microenvironment data indicates local humidity accumulation, drive the air conditioning system and the circulating fan system to work together to perform three-dimensional microenvironment dehumidification. S4. After germination, turn on the plant LED lighting system and enter the greening growth mode. The real-time substrate moisture content data fed back by the irrigation system is mapped to the water temperature inverse coupling model to generate a dynamic nighttime temperature setpoint to drive the air conditioning system to operate, build the root-crown balance physiological basis, drive the carbon dioxide control system to release carbon dioxide to the air conditioning system outlet, and deliver it to the seedling tray through the circulating fan system. S5. Based on the physiological basis of root-crown balance, seedling cultivation is carried out. By reconstructing the short-wavelength spectral output of the plant LED lighting system, wind field disturbance commands are generated to drive the circulating fan system to construct a wind-light synergistic physical acclimatization environment. S6. Verify the seedling growth indicators. When they meet the preset standards, generate an outbound command to drive the seedling storage system to remove the finished seedling trays.

2. The rice seedling raising method based on a plant factory according to claim 1, characterized in that, In step S3, the step of coordinating the driving air conditioning system and the circulating fan system to perform three-dimensional microenvironment dehumidification further includes: The central control system continuously monitors the local relative humidity data distributed on the multi-layer three-dimensional cultivation rack as microenvironment data. When the local relative humidity in the microenvironment data continues to be higher than the preset safety threshold or when the irrigation system detects the completion signal of the sprinkler operation, an air conditioning fan linkage dehumidification command is generated. Based on the dehumidification command linked to the air conditioner fan, the central control system drives the carbon dioxide control system to block the carbon dioxide supply, simultaneously drives the air conditioning system to switch from constant temperature mode to powerful dehumidification mode to output dry cold air, and forcibly starts the circulating fan system to pump the dry cold air into the shelf to create a gas-liquid coordinated dehumidification flow field.

3. The rice seedling raising method based on a plant factory according to claim 2, characterized in that, The circulating fan system includes a fan array arranged between multi-layer three-dimensional cultivation racks, with the air outlet direction pointing towards the seedling tray area; When constructing the gas-liquid synergistic dehumidification flow field, the circulating fan system generates forced convection based on the dry cold air output by the air conditioning system. The forced convection penetrates the dense area of ​​the three-dimensional cultivation rack, destroys the static high-humidity boundary layer on the surface of the rice seedling tray, and brings the accumulated water vapor into the circulation space. The air conditioning system in strong dehumidification mode then condenses and recovers the accumulated water vapor.

4. The rice seedling raising method based on a plant factory according to claim 1, characterized in that, In step S4, the step of mapping the real-time substrate moisture content data fed back by the irrigation system to the water temperature inverse coupling model further includes: The central control system collects the volumetric water content of the substrate in the seedling tray as real-time substrate water content data through a humidity detection probe. At the end of the daily light cycle, it is determined whether the real-time matrix moisture content is below a preset stress response threshold based on the real-time matrix moisture content data. When the water content falls below the stress response threshold, it is confirmed that the current period is a dry window, and the difference between the real-time matrix water content data and the stress response threshold is used as an input parameter to import the water temperature inverse coupling model.

5. The rice seedling raising method based on a plant factory according to claim 1, characterized in that, In step S4, the water temperature reverse coupling model is used to execute the following computational logic: A positive correlation mapping relationship is established between the nighttime temperature setpoint and the real-time matrix moisture content data. The lower the real-time matrix moisture content data, the closer the generated dynamic nighttime temperature setpoint is to the preset induced low temperature lower limit. The central control system uses the generated dynamic nighttime temperature setpoint to drive the air conditioning system to adjust the ambient temperature, and cooperates with the low-speed operation of the circulating fan system to ensure low temperature conduction. Through the synergistic effect of the low-temperature environment constructed by the air conditioning system and the real-time substrate moisture content data, which indicates the substrate dryness state, the above-ground growth of seedlings is inhibited and root elongation is induced.

6. The rice seedling raising method based on a plant factory according to claim 1, characterized in that, In step S5, the step of generating wind field disturbance commands to drive the circulating fan system to construct a wind-solar synergistic physical domestication environment further includes: The central control system generates wind field disturbance commands that include preset change frequencies and wind speed ranges. The circulating fan system is driven by the wind field disturbance command to perform frequency conversion and speed change or intermittent start and stop actions, and the fans set between the multi-layer three-dimensional cultivation racks are controlled to generate gusts of wind, creating an irregular disturbance wind field between the racks to apply mechanical stimulation to the seedlings.

7. The rice seedling raising method based on a plant factory according to claim 1, characterized in that, In step S5, the step of generating pneumatic pulse commands to drive the carbon dioxide control system to construct a wind-solar synergistic physical domestication environment further includes: The central control system generates pneumatic pulse commands containing preset frequency and pressure parameters. The pneumatic pulse command drives the solenoid valve array of the carbon dioxide control system to perform high-frequency intermittent action, controlling the carbon dioxide outlet at the air outlet of the air conditioning system to perform pulsed gas injection. After the pulsed airflow mixes with the air conditioning supply air, the circulating fan of the circulating fan system opens the disturbed wind field to apply mechanical stimulation to the seedlings.

8. The rice seedling raising method based on a plant factory according to claim 7, characterized in that, The construction of the wind-solar synergistic physical acclimatization environment also follows synchronous control logic: The effective hardening-off period is determined only when the plant LED lighting system outputs blue or ultraviolet light in response to the spectral reconstruction command and the disturbed wind field is in an active state, ensuring the synchronous superposition of mechanical stimulation and photomorphogenesis signal in the time dimension.

9. The rice seedling raising method based on a plant factory according to claim 1, characterized in that, The central control system performs closed-loop regulation of the wind-solar synergistic physical acclimatization environment based on the comprehensive seedling hardening intensity index, which is jointly determined by light quality factors and aerodynamic factors. The seedling hardening comprehensive intensity index is constructed to be positively correlated with the proportion of blue and ultraviolet light quantum flux in the full spectrum, and also positively correlated with the rotational speed change frequency and average wind speed of the circulating fan system.

10. A rice seedling raising system based on a plant factory, applied to the rice seedling raising method based on a plant factory as described in any one of claims 1-9, characterized in that, include: Multi-layer vertical cultivation racks are set up in the enclosed space of plant factories to accommodate rice seedling trays at high density. The seed soaking system, the drying system, and the sowing system are used for the pretreatment and sowing of rice seeds. The seedling storage system is used to transport rice seedling trays to the multi-layer three-dimensional cultivation rack; The air conditioning system includes air conditioning units and temperature and humidity sensors distributed on the multi-layer three-dimensional cultivation rack, used to regulate the temperature and humidity in the space; The circulating fan system includes a fan assembly disposed between the rows of the multi-layer three-dimensional cultivation racks, used to promote airflow circulation inside the racks and deliver the airflow of the carbon dioxide control system to the seedling tray area; The plant LED lighting system includes LED light groups installed on top of the multi-layered three-dimensional cultivation rack for providing adjustable spectrum artificial light; An irrigation system is used to provide water and nutrient solution to the rice seedling trays and to monitor the substrate moisture content; The carbon dioxide control system includes a carbon dioxide gas source and a control valve. The gas outlet of the carbon dioxide control system is located in the air supply channel of the air conditioning system and is used to deliver carbon dioxide gas to the multi-layer three-dimensional cultivation rack area. The central control system is used to control the operation of the above systems.

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