A method for screening a salt-tolerant pepper variety

Abstract

The application provides a screening method for salt-tolerant pepper varieties, comprising the following steps: S1, acquiring soil salt time series data of a target planting area in a continuous time period, the soil salt time series data being collected from multiple sampling points in the target planting area, and the soil salt concentrations of the multiple sampling points being different from each other at the same time point; S2, constructing multiple groups of concentration dynamic curves with different soil salt concentrations based on the soil salt time series data of the multiple sampling points; S3, constructing a salt stress treatment corresponding to each group of concentration dynamic curves based on the concentration dynamic curve; the change of the salt concentration in the cultivation substrate of each salt stress treatment with time dynamically follows the corresponding concentration dynamic curve; S4, planting multiple candidate pepper varieties under each salt stress treatment, and measuring evaluation indexes of each candidate pepper variety in the growth period; and S5, determining at least one target pepper variety based on the evaluation indexes. The application realizes dynamic following screening, and improves the consistency between indoor screening results and actual performance in the field.

Description

Technical Field

[0001] This application relates to the field of plant variety screening technology, and in particular to a method for screening salt-tolerant pepper varieties. Background Technology

[0002] my country has approximately 99.13 million hectares of saline-alkali land, widely distributed in the Northwest, North China, Northeast, and coastal areas. About 80% of this land remains undeveloped and represents a significant reserve of arable land. As a major vegetable and cash crop in my country, exploring the potential of chili pepper cultivation in saline-alkali land is crucial for alleviating the competition for land between food and vegetable crops. However, chili pepper cultivation in mildly to moderately saline-alkali land is severely limited. The primary prerequisite for achieving large-scale chili pepper cultivation in saline-alkali land is the selection of salt-tolerant varieties truly adapted to the target growing environment.

[0003] Existing methods for screening salt-tolerant pepper varieties are conducted in greenhouses or artificial climate chambers. The process involves: pre-preparing several fixed-gradient salt solutions (e.g., setting low, medium, and high salt concentration levels) to perform a one-time salinization treatment on the cultivation substrate of candidate pepper varieties, maintaining a constant concentration; after cultivating the candidate varieties under the set fixed salt concentration stress for a period of time, measuring their phenotypic indicators such as plant height and biomass, and selecting varieties with relatively better performance based on these indicators.

[0004] However, in actual field planting areas, soil salinity concentration exhibits a dynamic change characteristic that fluctuates continuously over time due to a combination of factors such as natural rainfall, evaporation, irrigation, and seasonal fluctuations in groundwater levels. This leads to a disconnect between indoor screening results and actual field performance, making it impossible to accurately obtain chili varieties that truly match the dynamic salinity environment of the target planting area. Summary of the Invention

[0005] The purpose of this application is to provide a method for screening salt-tolerant chili pepper varieties, so as to provide a method for screening chili pepper varieties that can accurately reproduce the dynamic changes in salinity in the field of the target planting area.

[0006] To address the aforementioned technical problems, the embodiments of this application provide the following technical solutions: This application provides a method for screening salt-tolerant chili pepper varieties, including: S1 acquires soil salinity time series data of the target planting area over a continuous period of time. The soil salinity time series data is collected from multiple sampling points in the target planting area, and the soil salinity concentration of the multiple sampling points is different at the same time point. S2 constructs multiple sets of dynamic concentration curves for different soil salinity concentrations based on the soil salinity time series data from multiple sampling points; S3 In an artificial climate chamber, based on the concentration dynamic curves of each group, a corresponding salt stress treatment is constructed; wherein, the change of salt concentration in the cultivation substrate of each salt stress treatment over time dynamically follows the corresponding concentration dynamic curve. S4. Multiple candidate chili pepper varieties were planted under each of the salt stress treatments, and the evaluation indicators of each candidate chili pepper variety were measured during the growth period. Based on the evaluation indicators, S5 determines at least one target chili pepper variety suitable for the target planting area.

[0007] In some embodiments, the soil salinity time series data for each sampling point includes time series data on the concentrations of multiple salt ions; the multiple salt ions are selected from at least two of sodium ions, potassium ions, calcium ions, magnesium ions, and chloride ions; Each set of concentration dynamic curves is constructed based on the concentration time series data of multiple salt ions corresponding to the sampling point, and each set of concentration dynamic curves contains sub-concentration dynamic curves that correspond one-to-one with multiple salt ions; The change in the concentration of each salt ion in the irrigation solution of each salt stress treatment over time dynamically follows the corresponding ion concentration dynamic curve.

[0008] In some embodiments, the soil salinity time series data for each sampling point corresponds to the soil salinity time series data for multiple soil layers at different depths; Each set of concentration dynamic curves is constructed based on the soil salinity time series data of multiple soil layers at different depths corresponding to the sampling points, and each set of concentration dynamic curves contains sub-concentration dynamic curves that correspond one-to-one with multiple soil layers at different depths; Based on the vertical salinity profile characteristics represented by the multiple sub-concentration dynamic curves in each set of concentration dynamic curves, irrigation solution concentration control parameters that change over time are determined; irrigation is carried out on the corresponding cultivation substrate for the salt stress treatment according to the irrigation solution concentration control parameters, so that when the actual salinity profile of the cultivation substrate in the vertical direction is within a preset time step and the profile error is within a preset tolerance range, it matches the target salinity profile represented by the multiple sub-concentration dynamic curves.

[0009] In some embodiments, step S1 further includes: acquiring environmental parameter time series data and soil moisture time series data of multiple sampling points, wherein the environmental parameter time series data and the soil moisture time series data correspond to the soil salinity time series data in time. The S2 step further includes: constructing multiple sets of environmental parameter curves and multiple sets of soil moisture curves based on the environmental parameter time series data and the soil moisture time series data of multiple sampling points, respectively. The S3 step further includes: constructing the salt stress treatment corresponding to each sampling point based on the concentration dynamic curve, the environmental parameter curve, and the soil moisture curve; wherein, the changes in salt concentration, environmental parameters, and water content in the cultivation substrate of each salt stress treatment over time dynamically follow the corresponding curves.

[0010] In some embodiments, the method for dynamically tracking the change in salt concentration in the cultivation substrate under each of the salt stress treatments over time according to the corresponding concentration dynamic curve includes: The current salt concentration value in the cultivation substrate of each salt stress treatment is acquired in real time or at a preset frequency. The current salt concentration value is compared with the target salt concentration value at the corresponding time point in the concentration dynamic curve to obtain the concentration deviation; Based on the concentration deviation, the concentration of the salt solution supplied to the cultivation substrate under salt stress treatment is adjusted.

[0011] In some embodiments, step S1 further includes: obtaining the area proportion of each of the soil salinity concentrations in the target planting area; Step S5 includes: S501 determines the weight of the corresponding salt stress treatment based on the area ratio of each of the soil salinity concentrations. S502 Based on the evaluation indicators, the evaluation results of each candidate chili pepper variety under each salt stress treatment are obtained; S503 Based on the weights, calculate the weighted average of the evaluation results of each candidate chili pepper variety under all salt stress treatments; The candidate chili pepper variety with the highest weighted average value is determined as the target chili pepper variety suitable for the target planting area.

[0012] In some embodiments, step S5 includes: S511 Based on the evaluation index, select at least one of the candidate chili pepper varieties that performs well from the multiple candidate chili pepper varieties under each of the salt stress treatments, and obtain multiple preliminary screening varieties. S512 divides the target planting area into multiple planting plots, and each planting plot plants multiple of the pre-screened varieties; S513 During the growth period of each of the pre-screened varieties, the evaluation index is measured, and based on the comprehensive evaluation results of the evaluation index of each of the pre-screened varieties in all the planting plots, at least one of the target chili pepper varieties suitable for the target planting area is determined.

[0013] In some embodiments, the evaluation index measured in step S4 is a first type of evaluation index, which includes at least one of salt damage index, plant height, root length, fresh weight, and chlorophyll content. The evaluation index measured in step S513 is a second type of evaluation index, which includes at least one of survival rate, growth vigor, number of flowers, fruit setting rate and stress resistance. The evaluation indicators also include a third type of evaluation indicator for evaluating the genetic stability of the salt and alkali tolerance trait of the target chili variety. The third type of evaluation indicator includes the genotype of the stress-resistance molecular marker of the target chili variety.

[0014] In some embodiments, step S5 is followed by: S6 cultivates the target chili variety in the target planting area using raised ridges and mulch film, and irrigates and fertilizes it according to a preset water and fertilizer supply plan using a drip irrigation system.

[0015] In some embodiments, the method further includes the following steps prior to step S6: Based on the location of the multiple sampling points and the corresponding soil salinity concentration in step S1, the target planting area is divided into multiple improvement plots, and each improvement plot corresponds to one sampling point; Organic amendments matching the corresponding soil salinity concentration are applied to each of the improved plots.

[0016] Compared with existing technologies, the method for screening salt-tolerant chili varieties provided in this application obtains soil salinity time series data from multiple sampling points in the target planting area over a continuous period of time. Moreover, the salinity concentration at the sampling points is different at the same time point, so that the obtained data can simultaneously reflect the spatial heterogeneity (differences in basic salinity levels at different sites) and temporal dynamics (continuous fluctuation characteristics driven by natural factors such as rainfall and evaporation) of salinity in the region.

[0017] Based on the aforementioned time-series data with both spatiotemporal dimensions, multiple sets of concentration dynamic curves are constructed. This transforms the complex and unsteady salinity changes in the field into a parameterized stress model that can be standardized and executed in an artificial climate chamber. In the artificial climate chamber, the salinity concentration of the cultivation substrate is controlled in real time according to each concentration dynamic curve. This allows salt stress treatment to break through the traditional static model of "one-time salt addition and constant maintenance," and to reproduce the unique salinity dynamic stress process of the target planting area with high fidelity.

[0018] Because the candidate chili pepper varieties were subjected to a dynamic stress environment synchronized with the actual salt concentration fluctuations in the field throughout their entire growth period, and evaluation indicators were measured under these conditions, their salt tolerance was no longer limited to an instantaneous response to a fixed salt concentration, but rather reflected a systematic adaptability to continuously fluctuating salt environments. Therefore, the target chili pepper varieties ultimately selected fundamentally avoided the field adaptability bias caused by environmental distortion in traditional static screening methods.

[0019] This invention introduces the real spatiotemporal dynamic salinity characteristics of the target planting area into the indoor screening system, realizing a paradigm shift from static constant screening to dynamic follow-up screening. This significantly improves the consistency between indoor screening results and actual field performance, thereby accurately obtaining chili pepper varieties that truly fit the dynamic salinity environment of the target planting area. Attached Figure Description

[0020] The above and other objects, features, and advantages of exemplary embodiments of this application will become readily understood by reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of this application are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein: Figure 1 A flowchart illustrating the screening method for salt-tolerant chili pepper varieties of this application is shown schematically. Detailed Implementation

[0021] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0022] It should be noted that, unless otherwise stated, the technical or scientific terms used in this application shall have the ordinary meaning as understood by one of ordinary skill in the art to which this application pertains.

[0023] The screening method provided by this invention has a clear process and is easy to operate. Key steps (such as salinity time series data collection, dynamic curve construction, and stress simulation) all have standardized implementation conditions and do not rely on complex equipment or special environments. This method is applicable to typical saline-alkali areas in Northwest, North, and Northeast my country, facilitating localized application and large-scale promotion in saline-alkali lands of different ecological types, and providing reliable technical support for the cultivation of specialty vegetable industries in saline-alkali lands.

[0024] like Figure 1 As shown, this application provides a method for screening salt-tolerant chili varieties, including: S1 acquires soil salinity time series data of the target planting area over a continuous period of time. The soil salinity time series data is collected from multiple sampling points in the target planting area, and the soil salinity concentration of the multiple sampling points is different at the same time point.

[0025] In some embodiments, data for characterizing soil salinity can be obtained in any of the following ways: Soil saturated extracts were prepared according to standard methods, and their conductivity was measured using a portable conductivity meter (hereinafter referred to as...). (Unit: dS / m); This method has good comparability and accuracy, and conforms to internationally accepted soil salinity assessment standards; In-situ conductivity was measured using an embedded soil salinity sensor (hereinafter referred to as...). (Unit: dS / m); This method enables non-destructive, continuous dynamic monitoring and is suitable for real-time feedback and process control. The total soluble salt content (based on dry soil mass, unit: g / kg) was determined by preparing a saturated soil extract and using a gravimetric method. This method directly reflects the absolute mass of soluble salts in the soil and has high accuracy. Measured by a portable conductivity meter Measured with embedded soil salinity sensor Combination: Established through synchronous sampling and The calibration model (such as linear regression relationship) between them will enable the real-time data of the embedded sensor. Data conversion with standards Comparable equivalent values ​​are obtained, thus balancing real-time measurement with data standardization, providing a reliable basis for accurate simulation and closed-loop control of salt stress. This application preferably uses... and A combination of methods.

[0026] First, before sampling, initial sampling points can be set up in the target planting area using a grid method. For example, the basic sampling units can be divided into 50 m × 50 m units, and an initial sampling point can be set up in the center of each unit, for a total of 20–30 initial sampling points.

[0027] Then, at the beginning of the chili pepper growing season (e.g., early April), topsoil samples (e.g., 0-20 cm) were collected simultaneously from all initial sampling points, and saturated extracts were prepared according to standard methods. The extracts were then measured using a portable conductivity meter. .

[0028] Based on each initial sampling point The measurement results were used to classify the initial sampling points according to the preset salinization level standards, including: Low salt: <2 dS / m; Medium salt content: 2 dS / m ≤ <4 dS / m; High salt content: ≥4 dS / m.

[0029] The above thresholds can be adjusted based on the salt tolerance of chili varieties or local agronomic practices.

[0030] Within each salinization level, if multiple If sampling points have similar values ​​(e.g., the relative deviation between any two points is ≤10%), then select one of them as the typical sampling point for that level. Preferably, [the following is a list of sampling points]. The point whose value is closest to the median within that grade group; if multiple points If they are the same, choose the point that is more centrally located and more representative.

[0031] Ultimately, three or more typical sampling points should be retained to ensure coverage of low, medium, and high salinity levels.

[0032] At each typical sampling point, an embedded soil salinity sensor is deployed (for continuous monitoring). Simultaneously, soil samples were collected and measured during the key growth stages of chili peppers (such as seedling stage, flowering stage, and fruiting stage). Soil samples are typically collected every 5–7 days; during periods when salinity may change dramatically (such as 1–3 days before or after events that cause rapid salt migration, such as rainfall or irrigation), the sampling frequency is increased to once a day, ultimately forming a high-resolution soil salinity time series containing multiple time points.

[0033] S2 constructs multiple sets of dynamic concentration curves for different soil salinity concentrations based on the soil salinity time series data from multiple sampling points.

[0034] Specifically, the measurements taken at each typical sampling point at each sampling time point... Value (or equivalent value after correction model transformation) The data were organized chronologically to form corresponding time-soil salinity concentration pairs. Subsequently, data visualization software (such as Microsoft Excel) was used for plotting. For each sampling point, the horizontal axis represented the number of days the pepper had grown since transplanting, and the vertical axis represented the corresponding soil salinity concentration value, thus forming a concentration dynamic curve that characterizes the dynamic change trend of soil salinity during the pepper's growth period.

[0035] Each typical sampling point corresponds to a unique set of soil salinity time series data, and this set of data uniquely corresponds to a concentration dynamic curve. That is, there is a one-to-one correspondence between the sampling point, the soil salinity time series data, and the concentration dynamic curve. In this way, the dynamic changes of soil salinity during the growth period of chili peppers under different initial salinization levels (low salinity, medium salinity, and high salinity) can be intuitively presented.

[0036] S3 In an artificial climate chamber, based on the concentration dynamic curves of each group, a corresponding salt stress treatment is constructed; wherein, the change of salt concentration in the cultivation substrate of each salt stress treatment over time dynamically follows the corresponding concentration dynamic curve.

[0037] Specifically, artificial climate chambers are controllable environmental experimental facilities widely used in agricultural, ecological and plant physiological research. They can integrate temperature and humidity sensors, light systems, CO2 control devices and central control systems, and can accurately simulate and stably maintain set environmental parameters such as temperature, humidity, light cycle and gas composition, thereby eliminating external climate interference and achieving highly repeatable plant cultivation conditions. There are currently many mature products on the market that can be directly used in the implementation of this scheme.

[0038] Multiple independent cultivation units (i.e. salt stress treatment units) are set up in an artificial climate chamber. Each cultivation unit implements a salt stress treatment defined by a set of concentration dynamic curves, so as to achieve a one-to-one correspondence between salt stress treatments, cultivation units and concentration dynamic curves.

[0039] To achieve dynamic matching of salt concentration over time with the concentration dynamic curve in the cultivation substrate for each of the aforementioned salt stress treatments, drip irrigation can be used for control. For example, an independent automatic drip irrigation system can be configured for each cultivation unit in an artificial climate chamber. This drip irrigation system includes a multi-channel intelligent fertigation device and drip irrigation pipelines connected to it; wherein, the drip irrigation pipelines are led out from the multi-channel intelligent fertigation device, laid along the edge of the salt stress treatment unit, and deliver irrigation solution directly into the cultivation substrate through insertable drippers (e.g., buried 2-5 cm below the soil surface to ensure effective moisture in the root zone).

[0040] The multi-channel intelligent fertigation system incorporates multiple storage tanks, each capable of holding deionized water and salt mother liquors of varying concentrations. The outlet of each tank is connected to a mixing chamber via a solenoid valve, and the mixing chamber integrates an online conductivity monitoring module. This multi-channel intelligent fertigation system is connected to the central control system of the artificial climate chamber via wired or wireless means.

[0041] Before the formal experiment, the central control system pre-executed a calibration procedure based on the concentration dynamic curve: by injecting a series of irrigation solutions with known conductivity into the cultivation substrate, and simultaneously measuring the concentration of the substrate saturated extract. Value, establish the relationship between irrigation fluid conductivity and target The mapping relationship between them.

[0042] During normal operation, the central control system determines the target number of growing days since transplanting for the next irrigation time. The system calculates the required salt concentration of the irrigation solution in real time based on the mapping relationship, and automatically adjusts the opening duration and flow rate ratio of the solenoid valves in each channel to complete the online mixing of the salt solution. Subsequently, the mixed irrigation solution is injected into the cultivation substrate at corresponding time points and in corresponding quantities through the drip irrigation pipeline, so that its salt concentration dynamically tracks the preset concentration dynamic curve.

[0043] In some embodiments, the method for dynamically tracking the change in salt concentration in the cultivation substrate under each of the salt stress treatments over time according to the corresponding concentration dynamic curve includes: The current salt concentration value in the cultivation substrate of each salt stress treatment is acquired in real time or at a preset frequency. The current salt concentration value is compared with the target salt concentration value at the corresponding time point in the concentration dynamic curve to obtain the concentration deviation; Based on the concentration deviation, the concentration of the salt solution supplied to the cultivation substrate under salt stress treatment is adjusted.

[0044] Specifically, embedded soil salinity sensors can be installed in the root zone of the cultivation substrate in each cultivation unit (e.g., at a depth of 2–5 cm below the dripper). During drip irrigation, the embedded soil salinity sensors acquire the current salinity concentration value of the cultivation substrate in each cultivation unit in real time or at a preset frequency. The soil salinity sensors communicate with the central control system of the artificial climate chamber via wired or wireless communication, uploading the real-time collected current salinity concentration value to the central control system.

[0045] The central control system pre-stores dynamic concentration curve data with the number of growth days since the chili pepper transplanting date as the x-axis. Each time a current salt concentration value is received, the system calculates the corresponding number of growth days based on the difference between the current precise system timestamp and the transplanting baseline time, and interpolates the value from the curve to obtain the precisely corresponding target value. The value is used to calculate the concentration deviation using the following formula:

[0046] in, Concentration deviation, in dS / m; The equivalent value after matrix calibration model transformation of the original sensor readings Value, in dS / m; The target at the current time point Value, in dS / m.

[0047] Subsequently, the central control system was based on The ratio of the salt solution supplied to this cultivation unit is dynamically adjusted: when -0.2dS / m ≤ When ≤0.2 dS / m, at this time Within the allowable error range, the system maintains the current ratio unchanged; when When the concentration is >0.2 dS / m, the mixing ratio of the mother salt solution in the mixing chamber is automatically reduced until... Falling back to within the allowable error range; when When the concentration is less than -0.2 dS / m, the mixing ratio of the mother salt solution in the mixing chamber is automatically increased until... It has fallen back to within the allowable error range.

[0048] It should be noted that the dynamic following referred to in this application means maintaining dynamic following within a preset allowable error range.

[0049] Regarding salt concentration, the permissible error range (e.g., the aforementioned -0.2 dS / m to +0.2 dS / m) is preset based on sensor measurement accuracy, irrigation system adjustment resolution, and the physiological tolerance threshold of chili peppers to short-term salt fluctuations. That is, the dynamic tracking of salt concentration and concentration dynamic curve described in this application means that at any given control time, the absolute value of the concentration deviation between the current salt concentration value of the cultivation substrate and the corresponding target salt concentration value does not exceed the preset permissible deviation threshold for the salt stress treatment. When the deviation between the measured concentration and the target curve remains within this permissible error range, dynamic tracking is considered to have been achieved, thus ensuring the accuracy of biological simulation while also considering the engineering feasibility and operational stability of the control system.

[0050] Similarly, the dynamic tracking of environmental parameters (including temperature, light, humidity, etc.), soil moisture content, and pH value over time with their corresponding dynamic curves, as described in this application, means that the deviation between the measured values ​​of each parameter and the target value of the dynamic curve at the corresponding time point remains within the preset allowable error range for that parameter (e.g., allowable error of ±1℃ for temperature, ±3% for soil moisture content, and ±0.2% for pH). By configuring corresponding sensors and closed-loop control modules in each salt stress treatment unit, the synchronous dynamic tracking of the above-mentioned multiple environmental factors with the target curve can be achieved.

[0051] Through a closed-loop control process of monitoring-feedback-adjustment, salt fluctuations caused by factors such as evaporation, plant absorption, and leaching are effectively suppressed, ensuring that the salt concentration in each cultivation unit closely tracks its corresponding dynamic concentration curve, and significantly improving the accuracy and timeliness of salt stress simulation.

[0052] In some embodiments, the soil salinity time series data for each sampling point includes time series data on the concentrations of multiple salt ions; the multiple salt ions are selected from at least two of sodium ions, potassium ions, calcium ions, magnesium ions, and chloride ions; Each set of concentration dynamic curves is constructed based on the concentration time series data of multiple salt ions corresponding to the sampling point, and each set of concentration dynamic curves contains sub-concentration dynamic curves that correspond one-to-one with multiple salt ions; The change in the concentration of each salt ion in the irrigation solution of each salt stress treatment over time dynamically follows the corresponding ion concentration dynamic curve.

[0053] Specifically, time-series data of various salt ion concentrations at typical sampling points can be obtained using portable multi-parameter ion detection equipment, forming independent multi-dimensional time-series datasets for each typical sampling point.

[0054] Based on this dataset, a set of concentration dynamic curves is constructed for each sampling point, including sub-concentration dynamic curves corresponding to the measured ions, which respectively characterize the target trajectory of the change of each ion concentration with the number of days the pepper grows from the transplanting date.

[0055] To achieve multi-ion synergistic regulation, the central control system has multiple independent storage tanks that can separately hold deionized water and high-concentration mother liquors with different salt ions (such as NaCl, KCl, etc.). (e.g., solutions). The system interpolates the corresponding ion concentration dynamic curves based on the current number of days of chili pepper growth to obtain the target concentration of each ion, and performs addition constraint verification in conjunction with the co-ion relationship of each mother liquor salt to ensure the physicochemical compatibility of the mixing scheme.

[0056] Simultaneously, a solid-state ion-selective electrode array is arranged on the drip irrigation line of each cultivation unit (preferably in the bypass flow tank at the outlet of the mixing chamber). The irrigation solution to be dripped into the substrate is monitored online at a preset frequency (e.g., every 2 hours) to obtain the current measured concentration of each ion. The selectivity coefficient of the selected solid-state ion-selective electrode in an aqueous environment where the target ion and potential interfering ions coexist must meet predetermined accuracy requirements, and cross-sensitivity correction is introduced into the algorithm to eliminate the water substrate effect. After real-time temperature compensation, the electrode signal is converted into the concentration value of the corresponding ion through a pre-calibrated Nernst response model.

[0057] The system compares the measured concentration of each ion with its corresponding target concentration, calculates the concentration deviation of each ion, and independently adjusts the opening duration and flow rate ratio of the corresponding mother liquor channel solenoid valve based on the deviation of each ion. This allows the concentration of each target salt ion in the irrigation solution to dynamically track its ion concentration dynamic curve. By precisely controlling the ion composition and dynamic trajectory of the irrigation solution at the input end, the system can reproduce the salt ion input characteristics of the target planting area to the greatest extent possible.

[0058] In some embodiments, the soil salinity time series data for each sampling point corresponds to the soil salinity time series data for multiple soil layers at different depths; Each set of concentration dynamic curves is constructed based on the soil salinity time series data of multiple soil layers at different depths corresponding to the sampling points, and each set of concentration dynamic curves contains sub-concentration dynamic curves that correspond one-to-one with multiple soil layers at different depths; Based on the vertical salinity profile characteristics represented by the multiple sub-concentration dynamic curves in each set of concentration dynamic curves, irrigation solution concentration control parameters that change over time are determined; irrigation is carried out on the corresponding cultivation substrate for the salt stress treatment according to the irrigation solution concentration control parameters, so that when the actual salinity profile of the cultivation substrate in the vertical direction is within a preset time step and the profile error is within a preset tolerance range, it matches the target salinity profile represented by the multiple sub-concentration dynamic curves.

[0059] Specifically, at typical sampling points in the target planting area, soil salinity time-series data were acquired at multiple different target soil depths (e.g., the surface layer of 0-10 cm, the middle layer of 10-20 cm, and the deep layer of 20-40 cm). This can be achieved by embedding soil salinity sensors at each depth. In conjunction with periodic stratified soil sampling to prepare saturated soil extracts, a portable conductivity meter was used to measure the conductivity. This is achieved by generating independent soil salinity time series data for each typical sampling point at each depth.

[0060] Based on this multi-depth dataset, a set of concentration dynamic curves is constructed for each typical sampling point, which includes sub-concentration dynamic curves corresponding to each depth, representing the target trajectory of the change in salt concentration of soil layer at each specific depth with the number of days of growth after pepper transplanting.

[0061] When simulating salt stress in cultivation units, based on the vertical salt profile characteristics characterized by multi-depth sub-concentration dynamic curves and combined with the water-salt transport lag effect, irrigation control parameters are inversely calculated through water-salt dynamics: First, the system reads the target ECs at each depth after a preset time step (e.g., 24 hours). eThe value is used to calculate the interlayer salinity gradient in order to determine in advance whether the target salinity profile will be "surface aggregation type" (concentration difference is significantly greater than 0) or "leaching type" (concentration difference is close to or less than 0).

[0062] Secondly, control parameters (including irrigation fluid conductivity and single irrigation volume) are determined in advance based on profile characteristics. For example, if the target is to be "surface-accumulating", the system outputs "low volume, high concentration" parameters to suppress deep seepage and keep salts on the surface; if the target is to be "leaching", the system outputs "large volume, low concentration" parameters to use gravity flow to drive surface salts to the lower layers.

[0063] Finally, the system controls the water and fertilizer equipment to irrigate according to the above parameters. Due to the physical lag in water infiltration and salt redistribution, after completing one irrigation, the system waits for a preset time step (until the substrate water and salt reach dynamic equilibrium) before acquiring the actual salt distribution through multi-layer salt sensors embedded in the substrate. The system compares the actual profile with the target sub-concentration dynamic curve (for example, setting the tolerance range for profile matching to each depth). The deviation should not exceed ±0.5 dS / m; if the actual surface aggregation is slow, the water volume should be further reduced in the next round; if the overall salinity is too low, the proportion of mother liquor should be increased in the next round, so that the actual vertical salinity profile evolution trend of the cultivation substrate matches the target profile within the allowable tolerance and time lag range.

[0064] In some embodiments, step S1 further includes: acquiring environmental parameter time series data and soil moisture time series data of multiple sampling points, wherein the environmental parameter time series data and the soil moisture time series data correspond to the soil salinity time series data in time. The S2 step further includes: constructing multiple sets of environmental parameter curves and multiple sets of soil moisture curves based on the environmental parameter time series data and the soil moisture time series data of multiple sampling points, respectively. The S3 step further includes: constructing the salt stress treatment corresponding to each sampling point based on the concentration dynamic curve, the environmental parameter curve, and the soil moisture curve; wherein, the changes in salt concentration, environmental parameters, and water content in the cultivation substrate of each salt stress treatment over time dynamically follow the corresponding curves.

[0065] Specifically, typical sampling points were selected in the target planting area, and time-series data on environmental parameters, soil moisture, and soil salinity were acquired simultaneously throughout the entire growth period of the chili peppers, ensuring that the three types of data were aligned in the time dimension. Among them, environmental parameters (including air temperature, light intensity, relative humidity, etc.) were continuously and automatically collected by deploying miniature weather stations; soil moisture data were acquired by burying FDR or TDR type soil moisture sensors.

[0066] Based on the above multi-source data, with the number of days of growth after pepper transplanting as the x-axis, multiple sets of dynamic curves were constructed for each sampling point, including sub-curves of environmental parameters such as temperature, light, and humidity, as well as dynamic curves of soil moisture and salinity.

[0067] During the stress simulation of step S3 in the artificial climate chamber, a multi-factor closed-loop regulation of "environment-water-salinity" is formed. To eliminate physical coupling conflicts among multiple factors, the system adopts a hierarchical decoupling scheduling strategy with "environmental parameters as the primary factor and water and salinity parameters as secondary factors." For environmental parameters (temperature, light, and humidity), as basic pre-variables, the existing temperature, light, and humidity control system in the climate chamber is directly called to force the tracking of the corresponding environmental parameter sub-curves; the evolution of environmental parameters will directly change the potential evaporation and transpiration rate of the substrate. For moisture and salinity, as follow-up variables, the controller synchronously acquires the measured moisture and salinity of the current cultivation substrate and compares them with the target values ​​at the corresponding time. The system dynamically feeds forward to compensate for the water and salinity baseline values ​​based on the evolution trend of environmental parameters: for example, when the light intensity curve is in an upward phase, the system predicts an increase in evaporation, automatically raises the trigger threshold of the moisture curve, and simultaneously slightly increases the ratio of the salinity stock solution to offset the rapid accumulation of surface salts that may be caused by strong evaporation. During specific irrigation, the system uses moisture deviation as the basis for calculating the irrigation trigger condition and baseline water volume, and simultaneously uses salinity deviation as the basis for adjusting the irrigation solution concentration (for example, if the substrate salinity is lower than the target value, the conductivity of the mixed solution is increased; if abnormal evaporation results in extremely low moisture content and high salinity, a large volume of diluent irrigation is prioritized to ensure plant survival, temporarily suspending precise tracking of the salinity curve, and reverting to salinity adjustment after moisture recovery). Finally, the system couples and outputs the target water volume and target conductivity for this irrigation.

[0068] By configuring corresponding sensors and closed-loop control modules in each salt stress treatment unit, the synchronous dynamic tracking of the aforementioned multiple environmental factors and target curves can be achieved. Furthermore, under extreme operating conditions where environmental parameters, moisture, and salinity physically couple and conflict, the system makes compromise adjustments based on a preset priority strategy of "environmental protection, water priority, and salt follow-up." The resulting instantaneous overshoot of moisture or salinity is still considered to be within the allowable error range within the overall dynamic evolution cycle.

[0069] Thus, each salt stress treatment unit rigorously reproduces the atmospheric environment evolution, water consumption rhythm and salt dynamic accumulation process of the corresponding field sampling point in the time dimension, and accurately reshapes the vertical salt profile characteristics in the spatial dimension, thereby forming a highly simulated multi-factor coupled salt stress environment.

[0070] Considering that saline-alkali land is often accompanied by dynamic fluctuations in pH value, in order to accurately obtain chili germplasm that truly has both salt and alkali tolerance capabilities, in some embodiments, step S1 further includes: acquiring soil pH time series data from multiple sampling points, wherein the soil pH time series data corresponds to the soil salinity time series data in time. The S2 step further includes: constructing multiple sets of pH dynamic curves based on the soil pH time series data from multiple sampling points; The S3 step further includes: constructing the salt stress treatment corresponding to each of the sampling points based on the concentration dynamic curve and the pH dynamic curve; wherein, the salt concentration and pH value in the cultivation substrate of each salt stress treatment change with time, dynamically following the corresponding curves, for example, by adding an acid / alkali mother liquor storage tank and coordinating the adjustment of its solenoid valve opening to achieve dynamic pH tracking.

[0071] To balance the scalability of the screening system with controllable hardware costs, the multiple independent cultivation units adopt a "gradient sharing, group distribution" design pattern in their hardware control architecture. For the concentration dynamic curves constructed based on the same salinity level (e.g., low, medium, high), cultivation units corresponding to all candidate varieties are divided into a control group. Each cultivation unit within the same control group shares the same set of control modules (i.e., a shared multi-channel intelligent fertigation device, ion-selective electrode array, and acid / alkali mother liquor adjustment unit) to output irrigation solution with the same target concentration, target ion composition, and target pH value. Each cultivation unit receives this shared irrigation solution only through an independent solenoid valve distribution branch. Therefore, regardless of the increase in the number of candidate varieties or the number of repetitions, the number of core dynamic control modules corresponds only to the number of salinity gradients in the target planting area, thus achieving large-scale parallel dynamic stress screening of varieties with extremely low incremental hardware costs.

[0072] S4 planted multiple candidate chili pepper varieties under each of the salt stress treatments, and measured the evaluation indicators of each candidate chili pepper variety during the growth period.

[0073] Specifically, candidate chili varieties include Longjiao No. 9 and Haijiao Wang.

[0074] In some embodiments, the evaluation index measured in step S4 is a first type of evaluation index, which includes at least one of salt damage index, plant height, root length, fresh weight, and chlorophyll content. Based on the evaluation indicators, S5 determines at least one target chili pepper variety suitable for the target planting area.

[0075] In some embodiments, step S1 further includes: obtaining the area proportion of each of the soil salinity concentrations in the target planting area; Step S5 includes: S501 determines the weight of the corresponding salt stress treatment based on the area ratio of each of the soil salinity concentrations. S502 Based on the evaluation indicators, the evaluation results of each candidate chili pepper variety under each salt stress treatment are obtained; S503 Based on the weights, calculate the weighted average of the evaluation results of each candidate chili pepper variety under all salt stress treatments; The candidate chili pepper variety with the highest weighted average value is determined as the target chili pepper variety suitable for the target planting area.

[0076] Specifically, each initial sampling point is set to represent the salinity level of its grid. The number of initial sampling points belonging to low, medium, and high salinity levels after classification is counted, and the actual area proportion of each salinization level in the target planting area is calculated (for example, if 15 out of 30 sampling points belong to low salinity, then the area proportion of low salinity area is 50%, and the weight is 0.5).

[0077] The evaluation result refers to the score obtained by comprehensively quantifying multiple Class I evaluation indicators of a candidate chili pepper variety under specific salt stress treatment. In practical applications, conventional comprehensive evaluation models such as the membership function method can be used to standardize positive indicators (such as fresh weight) and negative indicators (such as salt damage index) and assign weights to sum them, thereby transforming multidimensional indicators into a comprehensive evaluation result of 0–100 points.

[0078] For example, assuming the target planting area has low, medium, and high salinity areas accounting for 50%, 30%, and 20%, respectively, the evaluation scores of "Longjiao No. 9" under the three stresses are 90, 75, and 40 points, respectively, with a weighted score of 75.5 points; the corresponding scores of "Haichao Wang" are 85, 60, and 65 points (performing well under high salinity but with average growth under medium and low salinity), with a weighted score of 73.5 points. Since 75.5 points is greater than 73.5 points, "Longjiao No. 9" is selected as the target variety.

[0079] This method avoids the limitations of screening based solely on a single salinity environment. By transforming the actual spatial heterogeneity of salinity in the field into evaluation weights, the selected varieties are not winners of a certain extreme habitat, but rather the comprehensive optimal varieties that fit the overall salinity pattern of the target planting area, thereby ensuring the actual yield and benefits of the field.

[0080] In other embodiments, step S5 includes: S511 Based on the evaluation index, select at least one of the candidate chili pepper varieties that performs well from the multiple candidate chili pepper varieties under each of the salt stress treatments, and obtain multiple preliminary screening varieties. S512 divides the target planting area into multiple planting plots, and each planting plot plants multiple of the pre-screened varieties; S513 During the growth period of each of the pre-screened varieties, the evaluation index is measured, and based on the comprehensive evaluation results of the evaluation index of each of the pre-screened varieties in all the planting plots, at least one of the target chili pepper varieties suitable for the target planting area is determined.

[0081] In some embodiments, the evaluation index measured in step S513 is a second type of evaluation index, which includes at least one of survival rate, growth vigor, number of flowers, fruit setting rate, and stress resistance.

[0082] In some embodiments, the evaluation index further includes a third type of evaluation index for evaluating the genetic stability of the salt and alkali tolerance trait of the target chili variety, wherein the third type of evaluation index includes the genotype of the stress-resistance molecular marker of the target chili variety.

[0083] Specifically, firstly, based on the aforementioned first-category evaluation indicators, top-performing candidate varieties (e.g., two) are selected from each salt stress treatment as initial screening varieties. Then, the target planting area is divided into multiple field planting plots, each located within an area of ​​different salinity levels, ensuring overall coverage of all salinity levels within the target area. Within each salinity level area, all initially screened varieties are simultaneously planted (e.g., "Longjiao No. 9" and "Haijiao Wang" are simultaneously planted in low, medium, and high salinity plots). In the subsequent S513 evaluation, the evaluation indicators measured for the same initially screened variety in plots of different salinity levels are aggregated and the final average is calculated. This average is used as the comprehensive evaluation result for the variety in the target planting area.

[0084] During the retesting phase (corresponding to step S513), the second type of evaluation indicators are determined. Growth vigor can be assessed by measuring morphological indicators such as plant height, stem diameter, and leaf spread. Stress resistance is specifically manifested in the degree of resistance to secondary diseases induced by salinity and alkali (such as root rot) or physiological damage symptoms in the plant (such as leaf yellowing rate). Simultaneously, a third type of evaluation indicator can be introduced to verify the genetic stability of the variety's salt tolerance trait. The evaluation of this molecular marker genotype can be performed by extracting leaf DNA during the seedling stage for preliminary verification, or by sampling and retesting before the final selection.

[0085] For example, after initial screening, varieties such as "Longjiao No. 9" and "Haijiao Wang" were retained and entered into field trials. Tests showed that "Longjiao No. 9" had a higher fruit set rate and a significantly lower incidence of root rot than "Haijiao Wang" (excellent in the second category of indicators), and its salt tolerance molecular marker detection results showed that the target gene banding was stable and consistent (meeting the third category of indicators). Ultimately, "Longjiao No. 9" was identified as the target variety.

[0086] By examining agronomic traits in real field communities (the second type of indicator) and verifying genetic stability at the molecular level (the third type of indicator), we ensure that the selected varieties are not only salt-tolerant in the laboratory, but also disease-resistant, high-yielding, and stable in actual agricultural production.

[0087] In some embodiments, step S5 is followed by: S6 cultivates the target chili variety in the target planting area using raised ridges and mulch film, and irrigates and fertilizes it according to a preset water and fertilizer supply plan using a drip irrigation system.

[0088] Specifically, to construct a complete cultivation method matching salt-tolerant varieties to reduce salt damage and improve survival rate and yield, the target planting area is prepared for sowing before transplanting. Well-rotted organic fertilizer (to reduce chemical fertilizer input) and soil conditioner are applied, and the soil is deeply tilled to a depth of 30-40 cm to improve soil aggregate structure and enhance water and fertilizer retention buffering capacity. Subsequently, high-ridge mulching cultivation is adopted, with the ridge height controlled at 25-30 cm. The ridge surface is covered with black mulch film, and drip irrigation tape is laid under the film. This method effectively reduces ineffective water evaporation, cuts off capillary action to reduce surface salt accumulation, and simultaneously increases soil temperature to promote early new root development, providing an excellent micro-ecological environment for salt-tolerant varieties.

[0089] In terms of water and fertilizer management, a precise water and fertilizer plan of "small amounts, multiple times, and supply on demand" is implemented based on the drip irrigation system to further improve nutrient utilization: during the seedling stage, drip irrigation is used to apply root-promoting water-soluble fertilizer to accelerate seedling establishment and root development; during the flowering period, a high-phosphorus and potassium formula is switched to promote flower bud differentiation; during the fruit expansion period, calcium, magnesium, and other micronutrients are precisely supplemented, and biological agents can be applied to enhance the plant's physiological resistance to stress. During the growing season, simplified pruning and green pest and disease control are implemented to achieve simplified management throughout the entire process.

[0090] Field verification has shown that this application integrates variety selection and cultivation. By deeply coupling the salt-tolerant varieties selected from S5 with the aforementioned supporting cultivation model, a synergistic "variety-soil-water and fertilizer-management" chain is formed, resulting in a transplant survival rate of over 90% (25%–35% higher than traditional methods), a 15%–25% increase in yield per mu (667 square meters), and a marketable rate increase of over 10%. This model effectively revitalizes mildly to moderately saline-alkali land. Without altering the underlying properties, it promotes stable and efficient chili pepper cultivation in moderately saline-alkali land through "salt-tolerant varieties + microenvironmental regulation + integrated water and fertilizer management," ultimately achieving a win-win situation for both economic and ecological benefits.

[0091] In some embodiments, the method further includes the following steps prior to step S6: Based on the location of the multiple sampling points and the corresponding soil salinity concentration in step S1, the target planting area is divided into multiple improvement plots, and each improvement plot corresponds to one sampling point; Organic amendments matching the corresponding soil salinity concentration are applied to each of the improved plots.

[0092] Specifically, based on the location of each grid sampling point in step S1 and the measured soil salinity concentration, the target planting area is divided into multiple grid-shaped improvement plots (i.e., each plot corresponds to a grid where a sampling point is located).

[0093] Subsequently, the application rate of organic amendments was matched according to the salt concentration gradient of each improved plot. For example, in plots with high salt concentration, decomposed organic fertilizer or straw was applied to increase soil cation exchange capacity and buffering capacity, while in plots with low salt concentration, conventional standards were applied. This achieves "salt-dependent amendment," providing a more uniform rhizosphere microenvironment for subsequent high-ridge mulching cultivation.

[0094] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for screening salt-tolerant chili pepper varieties, characterized in that, include: S1 acquires soil salinity time series data of the target planting area over a continuous period of time. The soil salinity time series data is collected from multiple sampling points in the target planting area, and the soil salinity concentration of the multiple sampling points is different at the same time point. S2 constructs multiple sets of dynamic concentration curves for different soil salinity concentrations based on the soil salinity time series data from multiple sampling points; S3 In an artificial climate chamber, based on the concentration dynamic curves of each group, a corresponding salt stress treatment is constructed; wherein, the change of salt concentration in the cultivation substrate of each salt stress treatment over time dynamically follows the corresponding concentration dynamic curve. S4. Multiple candidate chili pepper varieties were planted under each of the salt stress treatments, and the evaluation indicators of each candidate chili pepper variety were measured during the growth period. Based on the evaluation indicators, S5 determines at least one target chili pepper variety suitable for the target planting area.

2. The method for screening salt-tolerant chili varieties according to claim 1, characterized in that, The soil salinity time series data for each sampling point includes time series data on the concentrations of multiple salt ions; the multiple salt ions are selected from at least two of sodium ions, potassium ions, calcium ions, magnesium ions, and chloride ions; Each set of concentration dynamic curves is constructed based on the concentration time series data of multiple salt ions corresponding to the sampling point, and each set of concentration dynamic curves contains sub-concentration dynamic curves that correspond one-to-one with multiple salt ions; The change in the concentration of each salt ion in the irrigation solution of each salt stress treatment over time dynamically follows the corresponding ion concentration dynamic curve.

3. The method for screening salt-tolerant chili varieties according to claim 1, characterized in that, The soil salinity time series data for each sampling point corresponds to the soil salinity time series data for multiple soil layers at different depths; Each set of concentration dynamic curves is constructed based on the soil salinity time series data of multiple soil layers at different depths corresponding to the sampling points, and each set of concentration dynamic curves contains sub-concentration dynamic curves that correspond one-to-one with multiple soil layers at different depths; Based on the vertical salinity profile characteristics represented by the multiple sub-concentration dynamic curves in each set of concentration dynamic curves, irrigation solution concentration control parameters that change over time are determined; irrigation is carried out on the corresponding cultivation substrate for the salt stress treatment according to the irrigation solution concentration control parameters, so that when the actual salinity profile of the cultivation substrate in the vertical direction is within a preset time step and the profile error is within a preset tolerance range, it matches the target salinity profile represented by the multiple sub-concentration dynamic curves.

4. The method for screening salt-tolerant chili varieties according to claim 1, characterized in that, Step S1 further includes: acquiring environmental parameter time series data and soil moisture time series data of multiple sampling points, wherein the environmental parameter time series data and the soil moisture time series data correspond to the soil salinity time series data in time. The S2 step further includes: constructing multiple sets of environmental parameter curves and multiple sets of soil moisture curves based on the environmental parameter time series data and the soil moisture time series data of multiple sampling points, respectively. The S3 step further includes: constructing the salt stress treatment corresponding to each sampling point based on the concentration dynamic curve, the environmental parameter curve, and the soil moisture curve; wherein, the changes in salt concentration, environmental parameters, and water content in the cultivation substrate of each salt stress treatment over time dynamically follow the corresponding curves.

5. The method for screening salt-tolerant chili varieties according to claim 1, characterized in that, The method for dynamically tracking the change in salt concentration over time in the cultivation substrate under each of the salt stress treatments, following the corresponding concentration dynamic curve, includes: The current salt concentration value in the cultivation substrate of each salt stress treatment is acquired in real time or at a preset frequency. The current salt concentration value is compared with the target salt concentration value at the corresponding time point in the concentration dynamic curve to obtain the concentration deviation; Based on the concentration deviation, the concentration of the salt solution supplied to the cultivation substrate under salt stress treatment is adjusted.

6. The method for screening salt-tolerant chili varieties according to claim 1, characterized in that, The S1 step further includes: obtaining the area proportion of each of the soil salinity concentrations in the target planting area; Step S5 includes: S501 determines the weight of the corresponding salt stress treatment based on the area ratio of each of the soil salinity concentrations. S502 Based on the evaluation indicators, the evaluation results of each candidate chili pepper variety under each salt stress treatment are obtained; S503 Based on the weights, calculate the weighted average of the evaluation results of each candidate chili pepper variety under all salt stress treatments; The candidate chili pepper variety with the highest weighted average value is determined as the target chili pepper variety suitable for the target planting area.

7. The method for screening salt-tolerant chili varieties according to claim 1, characterized in that, The steps in S5 include: S511 Based on the evaluation index, select at least one of the candidate chili pepper varieties that performs well from the multiple candidate chili pepper varieties under each of the salt stress treatments, and obtain multiple preliminary screening varieties. S512 divides the target planting area into multiple planting plots, and each planting plot plants multiple of the pre-screened varieties; S513 During the growth period of each of the pre-screened varieties, the evaluation index is measured, and based on the comprehensive evaluation results of the evaluation index of each of the pre-screened varieties in all the planting plots, at least one of the target chili pepper varieties suitable for the target planting area is determined.

8. The method for screening salt-tolerant chili varieties according to claim 7, characterized in that, The evaluation index measured in step S4 is a first-class evaluation index, which includes at least one of salt damage index, plant height, root length, fresh weight and chlorophyll content. The evaluation index measured in step S513 is a second type of evaluation index, which includes at least one of survival rate, growth vigor, number of flowers, fruit setting rate and stress resistance. The evaluation indicators also include a third type of evaluation indicator for evaluating the genetic stability of the salt and alkali tolerance trait of the target chili variety. The third type of evaluation indicator includes the genotype of the stress-resistance molecular marker of the target chili variety.

9. The method for screening salt-tolerant chili varieties according to claim 1, characterized in that, The process following step S5 also includes: S6 cultivates the target chili variety in the target planting area using raised ridges and mulch film, and irrigates and fertilizes it according to a preset water and fertilizer supply plan using a drip irrigation system.

10. The method for screening salt-tolerant chili varieties according to claim 9, characterized in that, The process preceding step S6 also includes: Based on the location of the multiple sampling points and the corresponding soil salinity concentration in step S1, the target planting area is divided into multiple improvement plots, and each improvement plot corresponds to one sampling point; Organic amendments matching the corresponding soil salinity concentration are applied to each of the improved plots.

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