Device and method for simulating influence of salinity stress in freezing and thawing periods on germination of rhizomes of emergent aquatic plants

Abstract

The invention discloses a device and a method for simulating influence of salinity stress in freezing and thawing periods on germination of rhizomes of emergent aquatic plants, and belongs to the field of germination experiments of emergent aquatic plants in cold and arid regions. The device comprises an outdoor main pool and a research laboratory auxiliary pool which are communicated through a closed channel with double gates, the bottoms of the main pool and the auxiliary pool are provided with sliding ways and moving ways, and translation lead screws in the moving ways are matched with electromagnets to drive a base frame to move without icebreaking; and the main pond is matched with a freeze thawing, salinity and nutritive salt regulation and control module. According to the method, an L18 (3 * 6) orthogonal table is adopted to design a freeze-thaw mode, salinity and nutritive salt three-factor experimental combination, a base frame is transferred to an auxiliary pool without icebreaking, layering morphology and physiological indexes are measured synchronously, harvesting is conducted at the last stage of an experiment, and data variance analysis is conducted. According to the invention, undisturbed monitoring of the experimental environment is realized, the composite stress environment is accurately restored, the three-factor effect is quantified, a scientific basis is provided for ecological restoration of the saline-alkali wetland, the operation is convenient, and the repeatability is high.

Description

Technical Field

[0001] This invention relates to the field of emergent plant germination experiments in cold and arid regions, specifically to a device and method for simulating the effect of salinity stress during freeze-thaw cycles on the germination of rhizomes in emergent plants. Background Technology

[0002] Global climate change and human activities have exacerbated the salinization process in coastal and inland wetlands, making salinity stress a key environmental factor threatening the stability of wetland ecosystems and the survival of plant communities. Emergent plants, as crucial primary producers and structural components of wetland ecosystems, directly determine the community's resilience and succession direction through the germination, colonization, and growth dynamics of their rhizomes. Especially in seasonally frozen soil regions or waters that freeze in winter, emergent plants must simultaneously cope with the combined stresses of low-temperature freezing, water salinity, and nutrient limitation, rather than just salinity stress. Their tolerance mechanisms and adaptation strategies provide important scientific evidence for ecological restoration.

[0003] Existing research indicates significant interspecific differences in the tolerance of different wetland plants to salinity, cold, and nutrients, and clear interactions exist among these environmental factors. For example, low nutrient levels exacerbate the damage of salinity stress to rhizomes, and rapid freezing and thawing amplifies the inhibitory effect of high salinity. However, current studies on the impact of salinity stress on emergent plants mostly use single salinity factor simulations, failing to consider the coupling effect of freeze-thaw cycles and nutrients. Furthermore, the experimental environments are disconnected from real-world combined stress scenarios in the field, making it difficult to accurately guide the ecological restoration of degraded saline-alkali wetlands.

[0004] To approximate real habitats, some researchers have attempted to conduct experiments directly in outdoor natural water bodies or large simulated ponds during winter, placing potted plants at the bottom of the ponds with different salinity gradients. However, this method struggles to achieve precise gradient control and orthogonal combination simulation of freeze-thaw cycles, salinity, and nutrients under controlled conditions. It also fails to quantify the main effects of each factor on rhizome germination and the interaction effects between factors, resulting in insufficient in-depth research on the compound stress tolerance mechanisms of emergent plants and a lack of targeted scientific evidence for wetland ecological restoration. Furthermore, after the water surface freezes in winter, it is difficult to obtain plant samples regularly and non-destructively for morphological and physiological measurements without damaging the experimental environment. The traditional solution is to manually break the ice and retrieve the plants, pots and all, from the bottom. However, this method has the following serious drawbacks, directly affecting the accuracy and reliability of the experimental data: First, it disrupts the stability of the experimental environment: repeated ice-breaking and dredging drastically disturbs the water, leading to sudden and inconsistent water temperatures before and after the experiment. Water temperature is a key factor affecting plant metabolism, especially rhizome germination and dormancy breaking. Fluctuations in water level also alter the hydrostatic pressure and gas exchange conditions experienced by the plants. These additional interference variables introduced by the measurement operation itself make it difficult to distinguish whether the plant response stems from the pre-set salinity gradient or from environmental fluctuations caused by the measurement, severely reducing the internal validity of the experiment.

[0005] Secondly, the operation is difficult and risky: For deep water or large-area experimental pools, retrieving heavy, muddy flowerpots on ice is labor-intensive, inefficient, and poses safety hazards such as people falling into the water and equipment damage.

[0006] Finally, high-frequency, non-destructive monitoring is not possible: ice-breaking and retrieval is a destructive sampling method, usually only performed once at the end of the experiment, or at a few time points for destructive harvesting of a portion of the samples. This cannot meet the research needs for continuous, non-destructive tracking and observation of rhizome germination dynamics (such as emergence time and rate) and seedling growth processes, resulting in the loss of a large amount of crucial temporal biological information.

[0007] There is an urgent need in this field for an experimental method that can simulate the orthogonal stress of three factors: freeze-thaw, salinity, and nutrients. Combined with a stable experimental setup, this method can accurately recreate the real environment of saline-alkali wetlands during the freeze-thaw period in cold and arid regions, enabling quantitative analysis of the effects of each factor. This will provide technical support for screening stress-resistant species and elucidating the adaptation mechanisms of plants to complex stresses. Summary of the Invention

[0008] The purpose of this invention is to provide a device and method for simulating the effect of salinity stress on the rhizome germination of emergent plants during freeze-thaw cycles. This invention addresses the problems in existing technologies, such as the disconnect between single salinity stress simulation and actual field conditions under combined stress, the inability to achieve accurate orthogonal simulation of the three factors of freeze-thaw, salinity, and nutrients, and the difficulty in quantifying the effects of each factor. This invention enables accurate simulation of rhizome germination of emergent plants under three-factor orthogonal stress, clarifies the main effects and interaction effects of each factor on rhizome germination, and provides a more accurate scientific basis for the ecological restoration of saline-alkali wetlands.

[0009] To achieve the above objectives, the present invention provides the following technical solution: a device for simulating the effect of salinity stress during freeze-thaw cycles on the germination of emergent plant rhizomes, comprising a main pool and flower pots. Several main pools are set up outdoors, and several base frames carrying multiple flower pots are placed in each main pool. Emergent plant rhizomes are buried in the flower pots. The effect of salinity on the germination of emergent plant rhizomes is observed by controlling different water salinities in the main pools. A strong magnet is fixedly connected to the bottom of the base frame, and the strong magnet slides in a slide rail. Each of the main pools is also connected to a secondary pool located in the research room through a closed channel. The closed channel is equipped with gates at both ends, and the base frame can move in the main pool, pass through the closed channel, and reach the secondary pool. The main pool, enclosed channel, and auxiliary pool are equipped with slides on the bottom surface and sliding channels under the bottom surface at corresponding positions of the slides, and the base frame slides guided by the slides; Each of the aforementioned channels is rotatably connected to a motor-driven translation screw, with a screw slider threaded onto the translation screw, and an electromagnet fixedly connected to the screw slider. The electromagnet attracts a strong magnet through magnetic force. The main pool and the auxiliary pool are equipped with a salvage device, which is used to salvage the base frame in the main pool and the auxiliary pool.

[0010] Preferably, the slide includes an exit slide, a translation slide, an auxiliary slide, and a detection slide. The number of exit slides is consistent with the maximum number of base frames that the main pool can accommodate. Multiple exit slides are parallel to each other. The translation slide and auxiliary slide intersect all exit slides perpendicularly and are located on the side closest to the closed passage. Only one translation slide is provided, and a parallel auxiliary slide is provided on each side of the translation slide. One detection slide is provided, connected to one of the exit slides. The slide and the exit slide are on the same straight line. The detection slide starts from the main pool, passes through the closed channel, and extends into the auxiliary pool. The exit slide, the translation slide, and the auxiliary slide are set in the main pool. The sliding track includes the exit sliding track, the translation sliding track, and the detection sliding track. Each exit slide is provided with a corresponding exit sliding track below it, and the length of the exit sliding track is shorter than the exit slide. The translation slide is provided with a translation sliding track below it, and the detection slide is provided with a detection sliding track below it. The exit sliding track, the translation sliding track, and the detection sliding track do not intersect.

[0011] Preferably, the strong magnet includes an outgoing magnet, a translation magnet, and a detection magnet, and both ends of the base frame are provided with handles for retrieval.

[0012] Preferably, the base frame is U-shaped, and several pot supports are fixedly connected to the base frame. The side walls of the flower pots are made of transparent material, and sampling holes with sealed caps are provided on the sides. The retrieval device is divided into a large hanger and a small hanger.

[0013] Preferably, the large gantry includes two symmetrically arranged large retrieval shafts. The lower ends of a side connecting rod are fixedly connected to both ends of each large retrieval shaft. The upper ends of the side connecting rods on the same side of the two large retrieval shafts are threaded to the same large lead screw. The same end of the two large lead screws is rotatably connected to the same large crossbar. The large lead screw is a bidirectional lead screw and is driven by a motor. The two ends of the large crossbar are vertically slidably connected to a large support rod through an electric lead screw or a cylinder. A large base is provided under each large crossbar. The lower ends of the two large support rods connected to the same large crossbar are fixedly connected to the same large base.

[0014] Preferably, the small rigging frame includes two symmetrically arranged small retrieval shafts. Each small retrieval shaft is fixedly connected to both ends of a Y-shaped rod. The other end of the Y-shaped rod is threaded to a small lead screw. The small lead screw is a bidirectional lead screw and is driven by a motor. Its two ends are rotatably connected to the upper end of an upper rod. The lower end of the upper rod is slidably connected to the lower rod. The upper rod is driven by a cylinder or an electric push rod.

[0015] The simulation method for the effect of salinity stress during freeze-thaw cycles on the rhizome germination of emergent plants using a simulation device includes the following steps: A. Preparation of experimental facilities; Determine the number of main ponds needed based on the salinity gradient required for the experiment, and prepare flower pots and base frames according to the number of plants; B. Preparation of experimental soil: Select native soil without submerged plant propagules as experimental substrate; soak the substrate in clean water several times to ensure that excess salt is washed away, and let it air dry for later use; mix it thoroughly with 3mm sieved fine sand at a volume ratio of 1:1, remove large benthic animals from the mud, mix and let it air dry for later use, and use the mixture of sand and soil as experimental soil; select flower pots and place the above mixture in the flower pots; C. Preparation of underground rhizomes of emergent plants: Emergent plants were selected as the research object of this experiment. In winter, a number of healthy and uniform rhizomes of emergent plants were collected from lakes with abundant distribution. The bottom mud on the roots was carefully washed away with clean water, and the rhizomes of emergent plants were transplanted into flower pots for later use. D. Experimental Implementation Process: A cosmic simulation experiment on the effects of salinity stress on emergent plants was conducted in the main pool. Flower pots of emergent plant samples prepared in step C were placed in the main pool with different salinity gradients. Salinity stress control: Use edible NaCl granules as solute to prepare salinity culture solution. Prepare several salinity culture solutions of different concentrations and add them to the main pool. Transplant the emergent plant rhizomes selected in step C into flower pots with mixed substrate, and plant one emergent plant rhizome in each flower pot. E. Process Monitoring: The experiment began at the start of the ice-melting period, with monitoring conducted every 15 days. The monitoring process followed the ice-free transfer procedure of the device's base frame: the target base frame was smoothly transferred to the auxiliary pool using electromagnets and translation screws. The gates of the closed channel were operated on an open-close principle to prevent water from overflowing from the main pool and flowing into the auxiliary pool. The temperature of the auxiliary pool was adjusted to match the temperature of the main pool. Simultaneous measurement of morphological and physiological indicators was completed in the auxiliary pool or by retrieving the device. The monitoring system utilizes the combination of a base frame and an electromagnet to transfer the base frame to the auxiliary tank, thus enabling detection without breaking the ice and avoiding the impact of water temperature changes caused by repeated ice breaking. After monitoring is completed, the base frame is precisely returned to its original position in the main tank according to the original device procedure to continue the cultivation process. F. Data Analysis; The experiment lasted for 5 months, approximately one month after the ice melted. After the experiment, all the base frames in the main pool were retrieved from the water using a large hoist. The rhizomes / plants in the flowerpots were disassembled into layers, and samples from each soil layer were separated. The bottom was gently rinsed. The dry weight of the aboveground and underground parts, the length and number of stolons, the root length, and the plant height were measured for each soil layer and the whole plant. At the same time, the final values ​​of the physiological indicators of the rhizomes were measured: the remaining starch content and the antioxidant enzyme activity. The stratified monitoring data and the final comprehensive index data were integrated, and statistical analysis methods were used to conduct multi-factor ANOVA and orthogonal experimental ANOVA on the experimental data.

[0016] Preferably, in step D, three experimental factors are set: freeze-thaw mode, salinity, and nutrients. The levels of each factor are set based on actual field monitoring data of saline-alkali wetlands in cold and arid regions, as detailed below: Salinity (S): 6 levels, 0ppt, 2ppt, 4ppt, 6ppt, 8ppt, 10ppt, covering the wetland freshwater-slightly saline-severely saline gradient; Freeze-thaw mode (F): 3 levels, slow freeze-thaw, fast freeze-thaw, and fast freeze-thaw. Slow freeze-thaw has a cooling rate of 0.5℃ / h, freezing temperature of -2 to -5℃, heating rate of 0.5℃ / h, and melting temperature of 0 to 3℃. Fast freeze-thaw has a cooling rate of 2℃ / h, freezing temperature of -8 to -10℃, heating rate of 2℃ / h, and melting temperature of 3 to 5℃. Fast freeze-thaw has a cooling rate of 2℃ / h, freezing temperature of -8 to -10℃, heating rate of 0.5℃ / h, and melting temperature of 0 to 3℃. Nutrient ratio (N / P): 3 levels, low nutrient (TN=0.5mg / L, TP=0.03125mg / L), mesonutrient (TN=2.0mg / L, TP=0.125mg / L), and high nutrient (TN=5.0mg / L, TP=0.3125mg / L), corresponding to oligotrophic, mesotrophic, and eutrophic states of wetlands, with the N / P ratio fixed at 16:1; An L18 (3²×6¹) orthogonal array was used to design experimental combinations, with a total of 18 different factor level combinations. Each experimental combination was set up with 3 biological replicates. A blank control group was added: salinity 0 ppt, slow freezing and slow thawing, mesotrophic, as the experimental baseline. The main pools were allocated in the manner of 1 combination + 3 replicates = 3 main pools. An anti-seepage isolation zone was set between the main pools to prevent cross-contamination of factors.

[0017] Preferably, in step E, the morphological index determination includes measuring the germination rate of each soil layer, the total germination rate, the germination index, the seedling index, the seedling height, the leaf length / area, the stem diameter, the number of asexual clones, and the time of death. Where: germination index = Σ(Gt / Dt), Gt is the number of germinations at time t, and Dt is the number of germination days; Seedling survival index = (Number of seedlings / Number of germination points) × 100%; During the determination of physiological indicators, a small amount of non-destructive sampling was performed through the sampling hole on the side wall of the flowerpot. After sampling, the sample was immediately sealed with a cap to ensure that the salinity and nutrient environment were not disturbed. For the small amount of rhizome samples, the activities of antioxidant enzymes (SOD, POD), osmotic regulators (proline, soluble sugars), rhizome starch content, and relative cell membrane conductivity were measured.

[0018] Compared with existing technologies, the advantages of this invention are: it achieves non-destructive, in-situ plant transfer and monitoring, fundamentally ensuring the stability of core parameters of the experimental environment. Through the main pool-closed channel-sub-pool structure and the movable support frame design, researchers can smoothly transfer the support frame carrying the plants to the warm sub-pool via an underground, ice-free channel, even when the main pool is completely frozen. This process completely avoids disrupting the ice layer of the main pool, thus completely preventing drastic fluctuations in water temperature and water level caused by repeated ice breaking. This ensures that the water temperature, water level, and salinity concentration of each salinity gradient main pool remain highly stable throughout the months-long freeze-thaw experiment, reducing the interference of the measurement operation itself on the experimental environment to zero. This allows all observed plant physiological responses, such as germination time, growth, and mortality, to be accurately attributed to the preset salinity stress variable, greatly improving the accuracy and reliability of the experimental data.

[0019] This invention provides highly controllable, flexible, and efficient sample scheduling and measurement capabilities, improving experimental accuracy and throughput. Through a network of precisely arranged exit, translation, and detection tracks on the bottom of the main and auxiliary pools, along with a track-moving system driven by translation screws and electromagnets below, combined with a specific layout of strong magnets at the bottom of the base frame, automated and programmed transfer of any designated base frame is achieved. This design allows researchers to retrieve any repeatable sample from a specific salinity gradient pool for testing as needed, and then accurately return it to its original location after testing. This flexible scheduling capability supports high-frequency, tracking-style, non-destructive monitoring of plant growth dynamics, overcoming the limitations of traditional destructive sampling which only obtains endpoint data. It can capture the precise timing of key life events such as germination, emergence, and tillering, providing strong technical support for a deeper understanding of the dynamic effects of salinity stress.

[0020] This invention reduces the difficulty and risk of experimental operations, and enhances the feasibility and repeatability of long-term experiments. The clever combination of large and small retrieval devices with the sliding system and handles on the base frame makes retrieving individual samples from the secondary pool or recovering large numbers of samples at the end of the experiment labor-saving, quick, and accurate. The multi-gate system within the enclosed channel effectively prevents water flow between the main and secondary pools during sample transfer, avoiding water level changes that could affect plant growth in the main pool. These designs significantly reduce the labor costs and safety risks associated with heavy and delicate operations in cold, slippery environments, such as falls into water or equipment collisions. This makes large-scale, multi-repetition simulation experiments under real natural freeze-thaw conditions safer, more convenient, and more repeatable, facilitating verification and comparison by different research teams.

[0021] This invention achieves orthogonal stress simulation of three factors: freeze-thaw cycles, salinity, and nutrients. It accurately recreates the complex stress environment faced by emergent plants in saline-alkali wetlands during the freeze-thaw period in arid and cold regions, addressing the disconnect between existing single-factor salinity stress simulations and real-world field conditions. The experimental conclusions can directly guide the ecological restoration of saline-alkali wetlands in the field. Through an L18 (3²×6¹) orthogonal experimental design, it comprehensively examines different combinations of the three factors with a minimum number of experimental groups, accurately analyzing the main effects of each factor on rhizome germination and the interaction effects between factors, clarifying the synergistic / antagonistic patterns between key influencing factors. By screening the optimal factor combination for rhizome germination and determining the composite stress threshold, it provides specific environmental control standards and species selection criteria for the artificial restoration of emergent plants in wetlands with different salinity levels and nutrient states in arid and cold regions. Compared to the qualitative conclusions of previous single-factor salinity studies, the guidance scheme of this invention is more targeted and operable. Attached Figure Description

[0022] Figure 1 This is a structural diagram of the present invention in use; Figure 2 This is a schematic diagram of the main structure of the present invention; Figure 3 This is a schematic diagram of the gate structure of the present invention; Figure 4 This is a schematic diagram of the bottom structure of the main pool of the present invention; Figure 5 This is a schematic diagram of the translation screw structure of the present invention; Figure 6 This is a schematic diagram of the slide structure of the present invention; Figure 7 This is a schematic diagram of the base frame of the present invention; Figure 8 This is a schematic diagram of the structure of the large hanging frame of the present invention; Figure 9 This is a schematic diagram of the structure of the small hanger of the present invention; Figure 10This is a flowchart illustrating the steps of the simulation method of the present invention.

[0023] In the diagram: 1. Main pool; 101. Enclosed passage; 102. Auxiliary pool; 103. Slide; 1031. Exit slide; 1032. Translation slide; 1033. Auxiliary slide; 1034. Detection slide; 104. Transfer track; 1041. Exit transfer track; 1042. Translation transfer track; 1043. Detection transfer track; 105. Gate; 2. Base frame; 201. Basin support; 202. Strong magnet; 2021. Exit magnet; 2022. Translation magnet. 2023, Detecting magnet; 203, Ball bearing; 204, Handle; 3, Flower pot; 4, Translation screw; 401, Screw slider; 402, Electromagnet; 5, Large hanger; 501, Large retrieval shaft; 502, Side connecting rod; 503, Large screw; 504, Large crossbar; 505, Large support rod; 506, Large base; 6, Small hanger; 601, Small retrieval shaft; 602, Y-shaped rod; 603, Small screw; 604, Upper rod; 605, Lower rod. Detailed Implementation

[0024] The technical solutions of 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.

[0025] To address the issue of repeated ice-breaking and dredging causing severe water disturbance and resulting in abrupt and inconsistent water temperatures before and after experiments, thus affecting plant metabolism, a method was developed for plant transfer and monitoring without disrupting the main ice layer of the pond. This fundamentally ensures the stability of core parameters in the experimental environment. Please refer to [link / reference]. Figure 1-9 This invention provides a technical solution: a device for simulating the effect of salinity stress on the germination of emergent plant rhizomes during freeze-thaw cycles, comprising a main pool 1 and flower pots 3. Several main pools 1 are provided, and several base frames 2 are placed in each main pool 1. Several flower pots 3 are placed on the base frames 2, and holes are provided at the bottom of the flower pots 3. Emergent plant rhizomes are buried in the flower pots 3. The effect of salinity on the germination of emergent plant rhizomes is observed by controlling different salinities in the main pools 1. A retrieval device is provided for both the main pool 1 and the auxiliary pool 102 to retrieve the base frames 2 in the main pool 1 and the auxiliary pool 102. In this application, electrical components such as motors, cylinders, and push rods all use existing models.

[0026] Each main pool 1 is also connected to one end of a closed channel 101, and the other end of the closed channel 101 is connected to a secondary pool 102. The closed channel 101 is equipped with at least two gates 105, with the distance between the first and last gates 105 greater than the length of a base frame 2. The gates 105 are opened or closed by cylinders or electric push rods, etc., and can completely seal both ends of the closed channel 101, preventing water flow between the main pool 1 and the secondary pool 102. The main pool 1 is located outdoors, and the secondary pool 102 is located in the research room. The base frame 2 can move through the closed channel 101 in the main pool 1 to reach the secondary pool 102, so that the germination status of emergent plant rhizomes can be measured and recorded in the research room without breaking the ice. If needed, the main pool 1, closed channel 101, and secondary pool 102 can be equipped with transparent observation windows and waterproof cameras to photograph the emergent plant rhizomes to determine the plant status. The main pool 1, closed channel 101, and secondary pool 102 are equipped with inlet and outlet pipes and other supporting facilities.

[0027] To ensure that the transplanted plants do not disturb the water in the main pool 1 and do not damage the ice layer, slides 103 are provided on the bottom surfaces of the main pool 1, the enclosed channel 101 and the auxiliary pool 102. The base frame 2 is guided to slide through the slides 103. A transfer channel 104 corresponding to the slides 103 is provided under the bottom surfaces of the main pool 1, the enclosed channel 101 and the auxiliary pool 102.

[0028] Slide 103 includes an exit slide 1031, a translation slide 1032, an auxiliary slide 1033, and a detection slide 1034, such as... Figure 6 As shown, the number of exit slides 1031 is consistent with the maximum number of base frames 2 that the main pool 1 can accommodate. Multiple exit slides 1031 are parallel to each other. The translation slide 1032 and the auxiliary slide 1033 intersect all exit slides 1031 perpendicularly and are set on one side near the closed channel 101. Only one translation slide 1032 is provided. On each side of the translation slide 1032, there is an auxiliary slide 1033 parallel to it. There is one detection slide 1034. The detection slide 1034 is connected to one of the exit slides 1031. The detection slide 1034 and the exit slide 1031 are on the same straight line. The detection slide 1034 starts from the main pool 1, passes through the closed channel 101, and extends into the secondary pool 102. The exit slides 1031, translation slide 1032, and auxiliary slide 1033 are set in the main pool 1.

[0029] The sliding track 104 includes an outgoing sliding track 1041, a lateral sliding track 1042, and a detection sliding track 1043. Each outgoing slide 1031 has a corresponding outgoing sliding track 1041 below it, and the length of the outgoing sliding track 1041 is shorter than that of the outgoing slide 1031. The lateral sliding track 1042 is provided below the lateral sliding track 1032, and the detection sliding track 1043 is provided below the detection slide 1034. The outgoing sliding track 1041, the lateral sliding track 1042, and the detection sliding track 1043 do not intersect.

[0030] To facilitate measurement and retrieval of the base frame 2, the base frame 2 is U-shaped. Several pot supports 201 are fixedly connected to the base frame 2. The pot supports 201 can be shaped to support the flower pots 3, such as multiple positioning blocks, cylindrical shapes, or rings that cooperate with the support rods. A strong magnet 202 is fixedly connected to the bottom of the base frame 2. The strong magnet 202 slides in the slide rail 103. The strong magnet 202 includes an exit magnet 2021, a translation magnet 2022, and a detection magnet 2023. Several ball bearings 203 are rolled at the bottom of the base frame 2 to assist the base frame 2 in sliding in the main pool 1, the closed channel 101, and the secondary pool 102. Both ends of the base frame 2 are provided with handles 204 for retrieval. The handles 204 are inverted U-shaped and can be hung on the large hanger 5 or the small hanger 6. The side walls of the flower pots 3 are made of transparent material, and sampling holes with sealed caps are provided on the sides. The retrieval device consists of a large hanger 5 and a small hanger 6.

[0031] Each sliding track 104 is rotatably connected to a translation screw 4, which is driven by a motor. The translation screw 4 is threadedly connected to a screw slider 401, and an electromagnet 402 is fixedly connected to the screw slider 401. The electromagnet 402 can attract a strong magnet 202 through magnetic force.

[0032] To facilitate the retrieval method required for the experiment, retrieval devices are installed in the main pool 1 and the auxiliary pool 102 to retrieve the base frame 2 in the main pool 1 and the auxiliary pool 102.

[0033] The salvage device is a large lifting frame 5, which includes two symmetrically arranged large salvage shafts 501. The lower ends of a side connecting rod 502 are fixedly connected to both ends of each large salvage shaft 501. The upper ends of the side connecting rods 502 on the same side of the two large salvage shafts 501 are threaded to the same large lead screw 503. The same end of the two large lead screws 503 is rotatably connected to the same large crossbar 504. The large lead screw 503 is a bidirectional lead screw and is driven by a motor. The two ends of the large crossbar 504 are vertically and slidably connected to a large support rod 50 via an electric lead screw or a cylinder. 5. Each large horizontal bar 504 is provided with a large base 506. The lower ends of two large support bars 505 connected to the same large horizontal bar 504 are fixedly connected to the same large base 506. The large base 506 can be provided with universal wheels with locking function for movement. The length of the large retrieval shaft 501 is not less than the width of two base frames 2, so as to realize the simultaneous retrieval of multiple base frames 2. In order to facilitate the positioning of the base frame 2 when lowering it and aligning the base frame 2 with the slide rail 103, the large retrieval shaft 501 is provided with a corresponding groove for positioning.

[0034] The retrieval device is a small hanger 6, which includes two symmetrically arranged small retrieval shafts 601. Each small retrieval shaft 601 is fixedly connected to both ends of a Y-shaped rod 602. The other end of the Y-shaped rod 602 is threaded to a small lead screw 603. The small lead screw 603 is a bidirectional lead screw and is driven by a motor. Its two ends are rotatably connected to the upper end of an upper rod 604. The lower end of the upper rod 604 is slidably connected to a lower rod 605. The upper rod 604 is driven by a cylinder or an electric push rod. The small lead screw 603 can just retrieve one base frame 2, so as to retrieve a single base frame 2 and facilitate the measurement of the plant condition. According to the positioning needs, an auxiliary sliding rod can also be set between the two Y-shaped rods 602 to prevent the Y-shaped rod 602 from rotating with the small lead screw 603.

[0035] Main pool 1 is equipped with a freeze-thaw simulation module, a salinity control module, and a nutrient drip irrigation regulation module. Freeze-thaw simulation module: includes layered temperature sensors, microchannel temperature control / cooling device, ice thickness monitor and main pool outer wall insulation layer, to achieve precise control of freezing temperature, melting temperature and freeze-thaw rate; Salinity control module: includes a salinity sensor, salt / water replenishment inlet, and is configured with 0ppt, 2ppt, 4ppt, 6ppt, 8ppt, and 10ppt gradient salinity culture medium to maintain stable salinity in the main tank. Nutrient drip irrigation control module: Includes nutrient sensor and drip irrigation inlet, adds NaNO3 and KH2PO4 at a ratio of N / P=16:1 to achieve precise control of three nutrient gradients: low, medium and high.

[0036] Flowerpot 3 has a layered structure, consisting of three independent cultivation layers: the top layer (0-5cm), the middle layer (5-10cm), and the bottom layer (10-15cm). A water-permeable and air-permeable anti-weed layer is set between the layers. The anti-weed layer can be made of ecological restoration porous concrete, weed control cloth, or horticultural ground cover. The side walls are made of transparent material, and sampling holes with sealed caps are set on the side.

[0037] like Figure 10 This invention proposes a method for simulating the effect of salinity stress during freeze-thaw cycles on the rhizome germination of emergent plants. Taking Wuliangsuhai Lake as an example, the steps are as follows: A. Preparation of experimental facilities; Based on the number of combinations of the three-factor orthogonal experimental design of freeze-thaw-salinity-nutrients, determine the number of main pools 1 required, and prepare flower pots 3 and base frames 2 according to the number of plants; B. Preparation of experimental soil: Select local soil without submerged plant propagules as experimental substrate; the preliminary preparation work for the experiment began in April. Select a certain amount of silt from the bottom of Wuliangsuhai Lake area, soak the substrate in clean water several times to ensure that excess salt in the substrate is washed away, and let it air dry for later use; mix it thoroughly with 3mm sieved fine sand at a volume ratio of 1:1, and remove large benthic animals such as snails and shrimp from the inside of the silt. After mixing and air drying, use the mixture of sand and soil as experimental soil; select a flowerpot 3 with a height of 30cm and a bottom diameter of 25cm, place the above-mentioned mixed substrate in the flowerpot 3, and the depth of the substrate in the flowerpot 3 should be about 15cm; C. Preparation of underground rhizomes of emergent plants: Reed and cattail, typical emergent plants of Wuliangsuhai Lake, were selected as the research objects of this experiment. In winter, a number of healthy and equal rhizomes of the above-mentioned emergent plants were collected from the lake where they are abundant. The bottom mud on the roots was carefully washed away with clean water. The rhizomes of the emergent plants were then buried in flower pot 3 for later use. D. Experimental implementation process: A cosmic simulation experiment on the effect of salinity stress on emergent plants was carried out in the main pool 1. The emergent plant sample flower pots 3 prepared in step C were placed in the main pool 1 with different salinity gradients. Salinity stress control: Using edible NaCl particles as solute, a salinity culture medium was prepared. Several salinity culture media with different salinity concentrations were prepared and added to the main pool 1, the corresponding secondary pool 102, and the closed channel 101, respectively. The salinity of the main pool 1, the closed channel 101, and the secondary pool 102 was consistent. Step D consists of the following steps: D1. Three Factors and Level Settings: Three experimental factors were set up: freeze-thaw pattern, salinity, and nutrients. The levels of each factor were set based on actual field monitoring data of saline-alkali wetlands in cold and arid regions, as detailed below: Salinity (S): 6 levels, 0ppt, 2ppt, 4ppt, 6ppt, 8ppt, 10ppt, covering the wetland freshwater-slightly saline-severely saline gradient; Freeze-thaw mode (F): 3 levels, slow freeze-thaw, fast freeze-thaw, and fast freeze-thaw. Slow freeze-thaw has a cooling rate of 0.5℃ / h, freezing temperature of -2 to -5℃, heating rate of 0.5℃ / h, and melting temperature of 0 to 3℃. Fast freeze-thaw has a cooling rate of 2℃ / h, freezing temperature of -8 to -10℃, heating rate of 2℃ / h, and melting temperature of 3 to 5℃. Fast freeze-thaw has a cooling rate of 2℃ / h, freezing temperature of -8 to -10℃, heating rate of 0.5℃ / h, and melting temperature of 0 to 3℃. Nutrient ratio (N / P): 3 levels, low nutrient (TN=0.5mg / L, TP=0.03125mg / L), mesonutrient (TN=2.0mg / L, TP=0.125mg / L), and high nutrient (TN=5.0mg / L, TP=0.3125mg / L), corresponding to oligotrophic, mesotrophic, and eutrophic states of wetlands, with the N / P ratio fixed at 16:1.

[0038] D2. Orthogonal experimental combination design: An L18 (3²×6¹) orthogonal array was used to design experimental combinations, with a total of 18 different factor level combinations. Each experimental combination was set up with 3 biological replicates. A blank control group was added: salinity 0 ppt, slow freezing and slow thawing, mesotrophic, as the experimental baseline. The main pool was allocated in the manner of 1 combination + 3 replicates = 3 main pools. An anti-seepage isolation zone was set between the main pools to prevent cross-contamination of factors.

[0039] D3. Construction of a three-factor orthogonal stress environment: Transplant the emergent plant rhizomes selected in step C into flowerpots 3 with prepared mixed substrate, planting one emergent plant rhizome in each flowerpot; place the flowerpots 3 on the pot supports 201 of the base frame 2, and use the large hanger 5 or small hanger 6 or other tools to place multiple base frames 2 into each main pool 1, so that the strong magnets 202 of the base frame 2 are located in the exit slide 1031, the strong magnets 202 on the side away from the secondary pool 102 are the exit magnets 2021, the strong magnets 202 in the middle are the translation magnets 2022, and the strong magnets 202 on the side closer to the secondary pool 102 are the detection magnets 2023; Using the salinity control module, freeze-thaw simulation module, and nutrient drip irrigation regulation module of main pool 1, each main pool is adjusted to the factor level of the corresponding experimental combination. Main pool 1 is kept at a water level of 30cm. The water is continuously monitored for 7 days until the salinity and nutrient concentration of the main pool water / bottom sediment are stable, the freeze-thaw mode reaches the preset ice layer thickness, and the experimental environment is confirmed to meet the design requirements before the experiment is officially started.

[0040] E. Process Monitoring: The experiment started at the beginning of the ice-melting period, i.e., at the end of winter and the beginning of January. Monitoring was conducted every 15 days. The monitoring process followed the ice-free transfer procedure of the device's base frame: the target base frame 2 was smoothly transferred to the auxiliary pool 102 by the cooperation of electromagnet 402 and translation screw 4. The gate 105 of the closed channel 101 was operated on an open-close principle to prevent water from overflowing from the main pool 1 and flowing into the auxiliary pool 102. The temperature of the auxiliary pool 102 was adjusted to be consistent with the water temperature of the main pool. Simultaneous measurement of morphological and physiological indicators was carried out in the auxiliary pool 102. Morphological index measurements included germination rate of each soil layer, total germination rate, germination index, seedling index, seedling height, leaf length / area, stem diameter, number of asexual clones, and time of death. Where: germination index = Σ(Gt / Dt), Gt is the number of germinations at time t, and Dt is the number of germination days; Seedling survival index = (Number of seedlings / Number of germination points) × 100%; During the physiological index determination, a small amount of non-destructive sampling was performed through the sampling holes on the three side walls of the flowerpot. After sampling, the sample was immediately sealed with a cap to ensure that the salinity and nutrient environment were not disturbed. For the small amount of rhizome samples, the antioxidant enzyme activities (SOD, POD), osmotic regulators (proline, soluble sugar, rhizome starch content, and relative cell membrane conductivity) were measured. SOD was determined using the nitroblue tetrazolium photoreduction method, POD using the guaiacol method, proline using the acidic ninhydrin colorimetric method, soluble sugar using the anthrone colorimetric method, and starch using the iodine-potassium iodide colorimetric method.

[0041] Monitoring utilizes the cooperation of the base frame 2 and electromagnet 402 to transfer the base frame 2 to the auxiliary tank 102, thus achieving detection without breaking the ice and avoiding the impact of water temperature changes caused by repeated ice breaking. After monitoring is completed, the base frame 2 is precisely returned to its original position in the main tank 1 according to the original device procedure to continue cultivation. Specifically: When the base frame 2 is placed in the exit slide 1031, the exit magnet 2021, the translation magnet 2022, and the detection magnet 2023 are collinear. When monitoring is required, the electromagnet 402 below the corresponding base frame 2 is activated first, and then the motor is activated. The motor drives the translation screw 4 to rotate, the translation screw 4 drives the screw slider 401 to move, the screw slider 401 drives the electromagnet 402 to move, the electromagnet 402 drives the strong magnet 202 to move, and the strong magnet 202 drives the base frame 2 to move, sending the base frame 2 and the flower pots 3 on it to the secondary pool 102. Since the secondary pool 102 is located in the research room, the secondary pool 102 will not freeze. The closed channel 101 will also not freeze because it is buried deep underground. The temperature of the research room is controlled to be consistent with the water temperature to avoid affecting the germination of emergent plants.

[0042] Specifically, firstly, the translation screw 4 of the exit track 1041 is activated, and the electromagnet 402 on it attracts the exit magnet 2021, which is away from the auxiliary pool 102, causing it to move in the exit slide 1031. When the electromagnet 402 reaches its maximum moving distance on the exit track 1041, the exit magnet 2021 drives the base frame 2 to slide to the end of the exit slide 1031. At this time, the translation magnet 2022 is aligned with the translation slide 1032, and the exit magnet 2021 and the detection magnet 2023 are respectively aligned with the two auxiliary slides 1033. At this time, the electromagnet 402 is turned off. Secondly, the translation screw 4 of the translation track 1042 is activated, and its... The electromagnet 402 on the base 2 attracts the translation magnet 2022, causing it to move in the translation slide 1032. When it moves to the base 2 and aligns with the detection slide 1034, it stops and the electromagnet 402 is turned off. During this process, the exit magnet 2021 and the detection magnet 2023 slide in the two auxiliary slides 1033. Finally, the translation screw 4 of the detection slide 1043 is activated, and the electromagnet 402 on it attracts the detection magnet 2023, causing it to move in the detection slide 1034, driving the base 2 through the closed channel 101 to the auxiliary pool 102. At this time, the electromagnet 402 is turned off, and the base 2 can be retrieved to measure the emergent plants in it.

[0043] When the base frame 2 reaches the closed channel 101, the cylinder or electric push rod is first activated to open the first gate 105 near the main pool 1. The last gate 105 near the auxiliary pool 102 is closed at this time. After the base frame 2 has completely entered the closed channel 101, the first gate 105 is closed and then the last gate 105 is opened. The base frame 2 continues to move into the auxiliary pool 102. That is, the two gates 105 cannot be opened at the same time, so as to prevent water in the main pool 1 from rushing to the auxiliary pool 102 and ensure the water level in the main pool 1 is stable.

[0044] For the auxiliary pool 102, the small lifting frame 6 can be used for retrieval. Move the small lifting frame 6 to the designated position in the auxiliary pool 102, then activate the electric push rod or cylinder to lower the upper rod 604. The upper rod 604 drives the small retrieval shafts 601 into the water. The two small retrieval shafts 601 are located outside the handle 204 of the base frame 2. Then, start the motor, which drives the small lead screw 603 to rotate. The small lead screw 603 drives the two Y-shaped rods 602 closer together. Move the small retrieval shaft 601 close to the base frame 2 until it is below the handle 204. At this time, start the electric push rod or cylinder to raise the upper rod 604. The small retrieval shaft 601 enters the handle 204 and lifts the base frame 2 out. Measurement can then be performed. After measurement, put the base frame 2 back into the auxiliary pool 102 and position the strong magnet 202 in the detection slide 1034. Use the translation screw 4 to send the base frame 2 back. Repeat the operation to perform all the tests.

[0045] Once the experiment is complete, the large lifting frame 5 can be used to retrieve the base frame 2 in the main pool 1. Move the large lifting frame 5 to the designated position in the main pool 1, and then activate the electric push rod or cylinder to lower the large horizontal bar 504. The large horizontal bar 504 drives the large lead screw 503 to descend, which in turn drives the side connecting rod 502 to descend. The side connecting rod 502 then drives the large retrieval shaft 501 to descend into the water. The two large retrieval shafts 501 are located outside the handles 204 of the multiple base frames 2. Then, start the motor, which drives the large lead screw 503 to rotate. The large lead screw 503 drives the side connecting rod 502 above it to move closer together, and the side connecting rod 502 drives the large retrieval shaft 501 to move closer to the base frame 2 until the large retrieval shaft 501 is below the handle 204. At this point, activate the electric push rod or cylinder to raise the large horizontal bar 504. The large horizontal bar 504 enters the handle 204 and lifts the base frame 2 out. At this point, the final measurement is performed.

[0046] F. Data Analysis; The experiment lasted for 5 months, approximately one month after the ice melted. After the experiment, all the base frames 2 in the main pool 1 were retrieved from the water using a large hoist 5. The rhizomes / plants in the flowerpots 3 were disassembled into layers, and soil samples were separated from each layer. The bottom was gently rinsed. The dry weight of the aboveground and underground parts, the length and number of stolons, root length, and plant height of each soil layer and the whole plant were measured. At the same time, the final values ​​of the physiological indicators of the rhizomes were measured: residual starch content and antioxidant enzyme activity. The stratified monitoring data and the final comprehensive index data were integrated, and statistical analysis methods were used to conduct multi-factor ANOVA and orthogonal experimental ANOVA on the experimental data. The specific analysis content is as follows: Main effect analysis: Calculate the contribution rate of freeze-thaw pattern, salinity, and nutrient salts to rhizome germination indicators, and identify the key factors affecting rhizome germination; Interaction effect analysis: Analyze the significance of the interaction between any two factors to clarify the synergistic / antagonistic effects between factors; Optimal combination screening: Based on the comprehensive results of germination rate, seedling rate, morphological and physiological indicators, the optimal combination of factor levels for rhizome germination was screened. Stress threshold determination: The freeze-thaw-salinity-nutrient salt combined stress threshold for rhizome germination was determined by the influence curves of each factor level on germination indicators.

[0047] 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 simulation device for the effect of salinity stress during freeze-thaw cycles on the rhizome germination of emergent plants, comprising a main pool (1) and flower pots (3), characterized in that: Several main pools (1) are set up outdoors. Each main pool (1) contains several base frames (2) carrying multiple flower pots (3). The flower pots (3) are filled with emergent plant rhizomes. The effect of salinity on the germination of emergent plant rhizomes is observed by controlling the salinity of the water in different main pools (1). A strong magnet (202) is fixedly connected to the bottom of the base frame (2). The strong magnet (202) slides in the slide (103). Each of the main pools (1) is also connected to a secondary pool (102) located in the research room through a closed channel (101). The closed channel (101) is equipped with gates (105) at both ends. The base frame (2) can move through the closed channel (101) in the main pool (1) to reach the secondary pool (102). The main pool (1), the enclosed channel (101) and the auxiliary pool (102) are provided with slides (103) on the bottom surface and sliding channels (104) under the bottom surface at the corresponding positions of the slides (103). The base frame (2) is guided to slide through the slides (103). Each of the aforementioned sliding tracks (104) is rotatably connected to a motor-driven translation screw (4), and a screw slider (401) is threadedly connected to the translation screw (4). An electromagnet (402) is fixedly connected to the screw slider (401), and the electromagnet (402) attracts a strong magnet (202) through magnetic force. The main pool (1) and the auxiliary pool (102) are equipped with a retrieval device, which retrieves the base frame (2) in the main pool (1) and the auxiliary pool (102).

2. The device for simulating the effect of freeze-thaw period salinity stress on the rhizome germination of emergent plants according to claim 1, characterized in that: The slide (103) includes an exit slide (1031), a translation slide (1032), an auxiliary slide (1033), and a detection slide (1034). The number of exit slides (1031) is consistent with the number of the largest base frames (2) that the main pool (1) can accommodate. Multiple exit slides (1031) are parallel to each other. The translation slide (1032) and the auxiliary slide (1033) intersect all exit slides (1031) perpendicularly and are located on one side near the closed channel (101). Only one translation slide (1032) is provided. An auxiliary slide (1033) is provided on each side of the translation slide (1032) and is parallel to it. One detection slide (1034) is provided. The detection slide (1034) is connected to one of the exit slides (1031). The detection slide (1034) is connected to the exit slide (1031). The detection slide (1034) is located on the same straight line, starting from the main pool (1), passing through the closed channel (101), and extending to the auxiliary pool (102). The exit slide (1031), the translation slide (1032), and the auxiliary slide (1033) are set in the main pool (1). The slide (104) includes the exit slide (1041), the translation slide (1042), and the detection slide (1043). Each exit slide... Below each track (1031), there is a corresponding exit track (1041), and the length of the exit track (1041) is shorter than that of the exit track (1031). A translation track (1042) is set below the translation track (1032), and a detection track (1043) is set below the detection track (1034). The exit track (1041), translation track (1042), and detection track (1043) do not intersect.

3. The device for simulating the effect of freeze-thaw period salinity stress on the rhizome germination of emergent plants according to claim 2, characterized in that: The strong magnet (202) includes an outgoing magnet (2021), a translation magnet (2022), and a detection magnet (2023). Both ends of the base frame (2) are provided with handles (204) for retrieval.

4. The device for simulating the effect of freeze-thaw period salinity stress on the rhizome germination of emergent plants according to claim 1, characterized in that: The base frame (2) is U-shaped, and several pot holders (201) are fixedly connected on the base frame (2). The side wall of the flower pot (3) is made of transparent material, and a sampling hole with a sealing cap is provided on the side. The retrieval device is divided into a large hanging frame (5) and a small hanging frame (6).

5. The device for simulating the effect of freeze-thaw period salinity stress on the rhizome germination of emergent plants according to claim 4, characterized in that: The large gantry (5) includes two symmetrically arranged large retrieval shafts (501). The lower ends of a side connecting rod (502) are fixedly connected to both ends of each large retrieval shaft (501). The upper ends of the side connecting rods (502) on the same side of the two large retrieval shafts (501) are threaded to the same large lead screw (503). The same end of the two large lead screws (503) is rotatably connected to the same large crossbar (504). The large lead screw (503) is a bidirectional lead screw and is driven by a motor. The two ends of the large crossbar (504) are vertically slidably connected to a large support rod (505) through an electric lead screw or a cylinder. A large base (506) is provided under each large crossbar (504). The lower ends of the two large support rods (505) connected to the same large crossbar (504) are fixedly connected to the same large base (506).

6. The device for simulating the effect of freeze-thaw period salinity stress on the rhizome germination of emergent plants according to claim 4, characterized in that: The small gantry (6) includes two symmetrically arranged small retrieval shafts (601). Each small retrieval shaft (601) is fixedly connected to both ends of a Y-shaped rod (602). The other end of the Y-shaped rod (602) is threaded to a small lead screw (603). The small lead screw (603) is a bidirectional lead screw and is driven by a motor. Its two ends are rotatably connected to the upper end of an upper rod (604). The lower end of the upper rod (604) is slidably connected to the lower rod (605). The upper rod (604) is driven by a cylinder or an electric push rod.

7. A method for simulating the effect of freeze-thaw salinity stress on the rhizome germination of emergent plants using the simulation device described in any one of claims 1-6, characterized in that, The steps are as follows: A. Preparation of experimental facilities; Determine the number of main pools (1) required according to the salinity gradient required for the experiment, and prepare flower pots (3) and base frames (2) according to the number of plants. B. Preparation of experimental soil: Select soil from the habitat without submerged plant propagules as experimental substrate; soak the substrate in clean water several times to ensure that excess salt in the substrate is washed away, and let it air dry for later use; mix it thoroughly with 3mm sieved fine sand at a volume ratio of 1:1, remove large benthic animals from the mud, mix and let it air dry for later use, and use the mixture of sand and soil as experimental soil. Select a flowerpot (3) and place the above-mentioned mixed substrate inside the flowerpot (3); C. Preparation of underground rhizomes of emergent plants: Emergent plants were selected as the research object of this experiment. In winter, a number of healthy and equal rhizomes of emergent plants were collected from lakes with abundant distribution. The bottom mud on the roots was carefully washed away with clean water. The rhizomes of emergent plants were transplanted into flower pots (3) for later use. D. Experimental implementation process: A cosmic simulation experiment on the effect of salinity stress on emergent plants was carried out in the main pool (1). The emergent plant sample flower pots (3) prepared in step C were placed in the main pool (1) with different salinity gradients. Salinity stress control: Use edible NaCl particles as solute to prepare salinity culture solution, prepare several salinity culture solutions of different concentrations in sequence and add them to the main pool (1); transplant the emergent plant rhizomes selected in step C into flower pots (3) with mixed substrate prepared, and plant one emergent plant rhizome in each flower pot; E. Process monitoring: The experiment started at the beginning of the ice melting period, and monitoring was carried out every 15 days. The monitoring process followed the ice-free transfer procedure of the device's base frame: the target base frame (2) was smoothly transferred to the auxiliary pool (102) by the cooperation of electromagnet (402) and translation screw (4). The gate (105) of the closed channel (101) was operated according to the principle of opening and closing to prevent water in the main pool (1) from overflowing and rushing to the auxiliary pool (102). The temperature of the auxiliary pool (102) was adjusted to be consistent with the water temperature of the main pool (1). The morphological and physiological indicators were measured simultaneously in the auxiliary pool (102) or by retrieving the device. The monitoring utilizes the cooperation of the base frame (2) and the electromagnet (402) to transfer the base frame (2) to the auxiliary pool (102) so that the detection can be carried out without breaking the ice, avoiding the influence of water temperature changes caused by repeated ice breaking; after the monitoring is completed, the base frame (2) is accurately sent back to the original position of the main pool (1) according to the original device process to continue to receive cultivation. F. Data analysis; The experiment lasted for 5 months, about one month after the ice melted. After the experiment, a large hoist (5) was used to retrieve all the base frames (2) in the main pool (1) and bring them ashore. The rhizomes / plants in the flower pots (3) were disassembled in layers, and samples of each soil layer were separated. The bottom was gently rinsed. The dry weight of the aboveground part, the dry weight of the underground part, the length and number of stolons, the root length, and the plant height of each soil layer and the whole were measured respectively. At the same time, the final values ​​of the physiological indicators of the rhizomes were measured: the remaining starch content and the antioxidant enzyme activity. The layered monitoring data and the final comprehensive index data were integrated. The experimental data were analyzed using statistical analysis methods to perform multi-factor variance analysis and orthogonal experimental variance analysis.

8. The method for simulating the effect of salinity stress during freeze-thaw cycles on the rhizome germination of emergent plants according to claim 7, characterized in that, In step D, three experimental factors are set: freeze-thaw mode, salinity, and nutrients. The levels of each factor are set based on actual field monitoring data of saline-alkali wetlands in cold and arid regions, as detailed below: Salinity (S): 6 levels, 0ppt, 2ppt, 4ppt, 6ppt, 8ppt, 10ppt, covering the wetland freshwater-slightly saline-severely saline gradient; Freeze-thaw mode (F): 3 levels, slow freeze-thaw, fast freeze-thaw, and fast freeze-thaw. Slow freeze-thaw has a cooling rate of 0.5℃ / h, freezing temperature of -2 to -5℃, heating rate of 0.5℃ / h, and melting temperature of 0 to 3℃. Fast freeze-thaw has a cooling rate of 2℃ / h, freezing temperature of -8 to -10℃, heating rate of 2℃ / h, and melting temperature of 3 to 5℃. Fast freeze-thaw has a cooling rate of 2℃ / h, freezing temperature of -8 to -10℃, heating rate of 0.5℃ / h, and melting temperature of 0 to 3℃. Nutrient ratio (N / P): 3 levels, low nutrient (TN=0.5mg / L, TP=0.03125mg / L), mesonutrient (TN=2.0mg / L, TP=0.125mg / L), and high nutrient (TN=5.0mg / L, TP=0.3125mg / L), corresponding to oligotrophic, mesotrophic, and eutrophic states of wetlands, with the N / P ratio fixed at 16:1; The experimental combination was designed using an L18 (3²×6¹) orthogonal array, with a total of 18 different factor level combinations. Each experimental combination was set up with 3 biological replicates. A blank control group was added: salinity 0ppt, slow freezing and slow thawing, and mesonutrient, as the experimental baseline. The main pools were allocated in the manner of 1 combination + 3 replicates = 3 main pools (1). An anti-seepage isolation zone was set between the main pools to prevent cross-contamination of factors.

9. The method for simulating the effect of salinity stress during freeze-thaw cycles on the rhizome germination of emergent plants according to claim 7, characterized in that, In step E, the morphological index determination includes measuring the germination rate of each soil layer, the total germination rate, the germination index, the seedling index, the seedling height, the leaf length / area, the stem diameter, the number of asexual clones, and the time of death. Where: germination index = Σ(Gt / Dt), Gt is the number of germinations at time t, and Dt is the number of germination days; Seedling survival index = (Number of seedlings / Number of germination points) × 100%; When measuring physiological indicators, a small amount of non-destructive sampling was performed through the sampling hole on the side wall of the flowerpot (3). After sampling, the sealed cap was immediately inserted to ensure that the salinity and nutrient environment were not disturbed. For the small amount of rhizome samples, the antioxidant enzyme activity, SOD, POD, osmotic regulators, proline, soluble sugar, rhizome starch content, and relative cell membrane conductivity were measured.

Images