A coastal saline-alkali soil wheat stress-resistant high-yield breeding material screening method

Abstract

The present application relates to the field of wheat breeding and saline-alkali resistant germplasm screening, and discloses a kind of coastal saline-alkali soil wheat stress-resistant high-yield breeding material screening method;The same isolated generation of wheat candidate family is respectively arranged in two planting units, and two salt tracks with different salt peaks in different growth stages are formed under the condition that the target cumulative effective salt exposure is consistent;In the recovery stage after the salt peak, the newly formed recovery source tiller is marked, and after the salt in the root zone rises again, the earing and grain formation are continuously tracked, the recovery source earing proportion, the recovery source yield contribution proportion and the total grain yield are obtained, and the candidate family that meets the selection conditions under the two salt tracks is screened according to the selection conditions;Further determine the limiting growth stage of the candidate family, and adjust the salt exposure time sequence for subculture screening under the condition that the target cumulative effective salt exposure remains unchanged in the next isolated generation.

Description

Technical Field

[0001] This invention relates to the field of wheat breeding and salt-tolerant germplasm screening, specifically to a method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land. Background Technology

[0002] In coastal saline-alkali areas, soil salinity is not stable throughout the wheat growth cycle due to factors such as groundwater depth, evaporation intensity, precipitation leaching, and irrigation / drainage conditions. Instead, it may fluctuate, rising, falling, and then rising again in stages throughout the growth process. Because wheat responds differently to salt stress at different growth stages (tillering, jointing, and heading), even the same breeding material experiencing similar overall salt stress levels may show significant differences in tillering, heading, and grain formation depending on the stage at which the salt peak occurs. Therefore, screening for breeding materials with both stress resistance and high yield in coastal saline-alkali areas requires not only considering the salt levels the material can tolerate but also the temporal distribution of salt stress at different growth stages and its impact on subsequent yield formation.

[0003] Current methods for screening salt-tolerant or salt-alkali-tolerant wheat materials typically involve setting salt concentrations, salt pond treatment, or planting in saline-alkali soils. Indicators such as seedling rate, tiller number, plant height, ear number, and grain yield are measured at the seedling stage, mature plant stage, or throughout the entire growth period. Salt-tolerant materials are then determined based on individual indicators or comprehensive evaluation results. While this screening method reflects the overall performance of materials under given salt stress conditions, differences in the growth stages of different candidate materials mean that a particular material may exhibit better survival or yield due to its salt-sensitive stage coinciding with the actual salt peak, which does not necessarily indicate that the material possesses stable salt-resistance recovery ability. Furthermore, existing methods for assessing the recovery process after salt reduction usually focus on post-recovery plant height, tiller number, or final total yield, making it difficult to further distinguish whether the yield at maturity is contributed by the main stem and tillers already formed before salt stress or by the recovery growth that occurs after salt damage and continues to experience subsequent salt increases.

[0004] Meanwhile, in the continuous generation breeding selection process, existing methods often use the same salt concentration, the same salt pond conditions, or an overall increase in salt stress intensity to continue screening the selected materials. The specific salt-sensitive growth stages exposed in the previous segregating generation are usually not directly used to adjust the salt stress sequence of the next segregating generation. When the overall salt stress intensity changes, it is also difficult to distinguish whether the changes in the next generation's performance stem from an increase in the total amount of salt stress or from the material's true response to salt damage at a specific growth stage. Therefore, how to distinguish the impact of different salt peak sequences on the same wheat candidate family under conditions of comparable overall salt exposure levels, and how to continuously trace the source of tillers formed after salt damage recovery and their subsequent ear and grain formation, while simultaneously using the screened restrictive growth stages for targeted selection in the next segregating generation, are problems that need to be solved in the screening of stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali lands. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for screening stress-resistant and high-yield wheat breeding materials in coastal saline-alkali lands, thereby solving the technical problems existing in the prior art.

[0006] The above-mentioned technical objective of the present invention is achieved through the following technical solution: A method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land, characterized by comprising the following steps: S1: All wheat candidate families of the same segregating generation are assigned to the first planting unit and the second planting unit respectively, and the correspondence between the same wheat candidate family and the two planting units is established. S2: Monitor the changes in wheat root zone salinity in two planting units as the growth process progresses. Determine the cumulative effective salt exposure based on the increase in root zone salinity relative to the initial root zone salinity and the corresponding duration. Form a first salinity trajectory and a second salinity trajectory according to the same target cumulative effective salt exposure. Both the first and second salinity trajectories include the main salinity peak, the root zone salinity decrease process after the main salinity peak, and the re-increase process after the root zone salinity decreases. Moreover, the main salinity peaks of the two salinity trajectories are located at different wheat growth stages. S3: During the process of decreasing salinity in the root zone, the recovery stage is determined, and the newly formed tillers in the recovery stage are identified as recovery source tillers and their source is marked; after the salinity in the root zone rises again, the recovery source tillers are tracked until maturity to obtain the number of recovery source tillers, the number of effective ears formed by recovery source tillers, and the corresponding recovery source grain yield, and the total grain yield of the corresponding wheat candidate family is obtained; S4: Determine the proportion of ears formed from the recovery source based on the number of tillers and the number of effective ears; determine the contribution ratio of the recovery source yield based on the grain yield and total grain yield of the recovery source; determine the selection criteria based on the proportion of ears formed from the recovery source and the contribution ratio of the recovery source yield of the salt-tolerant control material in the same period and the total grain yield of the high-yield control material in the same period; retain wheat candidate families that meet the selection criteria under both the first and second salt trajectories. S5: For the retained wheat candidate families, compare their contribution ratio of recovery source yield under the two salinity trajectories, and determine the wheat growth stage at which the main salinity peak of the salinity trajectory with the lower contribution ratio of recovery source yield is located; when the contribution ratio of recovery source yield is the same under the two salinity trajectories, determine the restricted growth stage according to the recovery source grain yield under the two salinity trajectories, and retain the seed of the retained wheat candidate families respectively. S6: For wheat candidate families with a determined restricted fertility stage, the target cumulative effective salt exposure remains unchanged in the next segregation generation, the interval salt exposure in the non-restricted fertility stage is reduced, and the reduced interval salt exposure is added to the restricted fertility stage in equal amounts to form a reinforced salt trajectory; for wheat candidate families without a determined restricted fertility stage, the first and second salt trajectories continue to be used in the next segregation generation. Following steps S3 to S4, successive generations of screening were conducted, and wheat candidate families that met the selection criteria for two or more consecutive segregation generations were identified as high-yield and stress-resistant breeding materials for wheat in coastal saline-alkali lands.

[0007] Preferably, in step S1, the seeds of each generation of each wheat candidate family are divided into a first seed group and a second seed group, and sown in the first planting unit and the second planting unit respectively. The two planting units used the same sowing time, sowing density and basic cultivation conditions, and the planting positions of the first seed group and the second seed group were recorded according to the wheat candidate family number and plant position to maintain the correspondence of the same wheat candidate family under the first salinity trajectory and the second salinity trajectory.

[0008] Preferably, in step S2, the soil electrical conductivity of the wheat root zone is used to characterize the salinity of the root zone, and the soil electrical conductivity of the root zone before the formation of the salinity trajectory is used as the initial salinity of the root zone. For each monitoring interval where the root zone soil conductivity is higher than the initial root zone salinity, the increase in root zone soil conductivity relative to the initial root zone salinity at the start and end times of the monitoring interval is obtained. The product of the average of the two increases and the duration of the monitoring interval is taken as the interval salt exposure. The cumulative effective salt exposure is obtained by accumulating the salt exposure of each interval.

[0009] Preferably, in step S2, the historical root zone soil conductivity monitoring data of at least one complete wheat growth cycle in the target coastal saline-alkali area are processed according to the same cumulative effective salt exposure determination method as in step S2 to obtain the target cumulative effective salt exposure. By adjusting the saline water input period and freshwater leaching period of the first and second planting units, the salt exposure of each wheat growth stage is changed, so that the two planting units can reach the target cumulative effective salt exposure, and the period when the soil electrical conductivity of their respective root zones is at its maximum corresponds to different wheat growth stages.

[0010] Preferably, in step S3, after the main salt peak appears, the root zone soil electrical conductivity is continuously acquired at the same monitoring interval. When the root zone soil electrical conductivity acquired at three consecutive monitoring times decreases sequentially, the monitoring interval between the first two monitoring times is determined as the starting interval of the recovery phase. Initially identify the main stems and tillers that have already formed in the initial interval. Tillers that form after the initial interval and do not have initial identification are identified as recovery source tillers. Establish source identification between each recovery source tiller and the corresponding wheat candidate family number and plant position.

[0011] Preferably, in step S3, the soil electrical conductivity of the root zone is continuously acquired at monitoring intervals during the recovery phase. When the soil electrical conductivity of the root zone acquired at three consecutive monitoring times increases sequentially, it is determined that the salinity of the root zone has increased again. After the salinity in the root zone increases again, the source identifiers of each restored tiller are maintained until maturity. Based on the source identifiers, the number of restored tillers, the number of effective ears formed by restored tillers, and the grain quality formed by effective ears are counted. At the same time, the grain quality formed by all effective ears of the corresponding wheat candidate families is counted.

[0012] Preferably, in step S4, the ratio of the number of effective ears formed by the tillers from the recovery source to the number of tillers from the recovery source is determined as the recovery source ear formation ratio, the grain quality corresponding to the effective ears formed by the tillers from the recovery source is determined as the recovery source grain yield, and the ratio of the recovery source grain yield to the total grain yield formed by all effective ears of the corresponding wheat candidate line is determined as the recovery source yield contribution ratio.

[0013] Preferably, in step S4, salt-tolerant control material and high-yield control material are planted simultaneously in the first planting unit and the second planting unit, respectively; For each salt content trajectory, the proportion of ears formed from the recovery source of the salt-tolerant control material was used as the selection limit for ears formed, the proportion of yield contribution from the recovery source of the salt-tolerant control material was used as the selection limit for yield recovery, and the total grain yield of the high-yield control material was used as the selection limit for high yield. When the proportion of ears formed from the recovery source of a wheat candidate family is not lower than the ear-forming selection threshold, the proportion of yield contribution from the recovery source is not lower than the yield recovery selection threshold, and the total grain yield is not lower than the high-yield selection threshold, the wheat candidate family is deemed to have met the selection criteria under the salinity trajectory.

[0014] Preferably, in step S5, when the contribution ratio of the recovery source yield under the first salt trajectory and the second salt trajectory is different, the wheat growth stage corresponding to the main salt peak of the lower recovery source yield contribution ratio is determined as the restricted growth stage. When the contribution ratio of the recovery source yield is the same under the two salt trajectories, the wheat growth stage at which the main salt peak corresponding to the lower recovery source grain yield is located is determined as the growth restriction stage. When the contribution ratio of recovery source yield and the recovery source grain yield are the same under both salinity trajectories, the stage of restricted fertility is uncertain.

[0015] Preferably, in step S6, for wheat candidate families with a restricted reproductive stage, the salt exposure of at least one interval in the previous segregating generation that is in the unrestricted reproductive stage is determined, and the salt exposure of the interval is reduced in the next segregating generation. The reduction is increased to the salt exposure of the interval corresponding to the restricted reproductive stage, so that the sum of the salt exposure of each interval in the next segregating generation is consistent with the target cumulative effective salt exposure. For wheat candidate families whose reproductive stage has not been determined, the distribution pattern of salt exposure between the first and second salt trajectories in the next segregation generation remains unchanged.

[0016] In summary, the present invention has the following main beneficial effects: This application involves placing candidate wheat families from the same segregating generation in a first planting unit and a second planting unit, respectively. While maintaining the same target cumulative effective salt exposure in both planting units, the main salt peaks of the first and second salt trajectories are located at different wheat growth stages. This allows candidate families to be screened under different salt stress sequences under comparable overall salt stress levels. This avoids evaluating the salt tolerance of materials solely based on fixed salt concentrations or single salt peaks, and also reduces screening bias caused by differences in the growth process of candidate families that happen to avoid salt-sensitive stages. This improves the accuracy of screening wheat stress-resistant breeding materials in coastal saline-alkali lands and effectively eliminates stage-escape materials.

[0017] This application identifies the recovery phase during the decline of root zone salinity after the main salinity peak, identifies the source of newly formed tillers during the recovery phase, and continuously tracks the formation of effective ears and grains by these tillers after the root zone salinity rises again. Simultaneously, it screens based on the proportion of ears formed from the recovery source, the grain yield from the recovery source, the proportion of yield contribution from the recovery source, and the total grain yield. This extends the evaluation from simply survival, tillering, or final total yield to whether tillers formed after salinity damage can continue to be converted into effective yields after a further rise in salinity. This distinguishes materials that primarily rely on the yield formed by the main stem and tillers before stress from materials with genuine stress recovery and post-recovery yield formation capabilities, achieving a targeted screening effect for breeding materials that balances stress resistance, recovery ability, and high yield.

[0018] This application compares the yield contribution of the recovery source under the first and second salt trajectories of the same candidate family to determine the reproductive stage that has a greater restriction on the yield recovery of the candidate family. The reproductive stage that restricts the reproductive stage is then fed back to the next segregating generation. While keeping the target cumulative effective salt exposure unchanged, part of the salt exposure of the non-restricting reproductive stage is redistributed to the reproductive stage to form a reinforced salt trajectory. This is then combined with the reference salt trajectory for successive generations of screening. This allows the actual screening results of the previous segregating generation to directly participate in the salt stress timing setting of the next segregating generation. This avoids continuous screening by simply increasing the overall salt concentration or mechanically repeating the same salt treatment. It achieves the effect of targeted selection for the weak reproductive stage of the candidate family, improving the stability of screening for stress-resistant and high-yield traits in consecutive generations, and enhancing the reliability of genetic selection of breeding materials. Attached Figure Description

[0019] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0020] 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.

[0021] Example 1 refer to Figure 1 A method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land includes the following steps: S1: All wheat candidate families of the same segregating generation are assigned to the first planting unit and the second planting unit respectively, and the correspondence between the same wheat candidate family and the two planting units is established. S2: Monitor the changes in wheat root zone salinity in two planting units as the growth process progresses. Determine the cumulative effective salt exposure based on the increase in root zone salinity relative to the initial root zone salinity and the corresponding duration. Form a first salinity trajectory and a second salinity trajectory according to the same target cumulative effective salt exposure. Both the first and second salinity trajectories include the main salinity peak, the root zone salinity decrease process after the main salinity peak, and the re-increase process after the root zone salinity decreases. Moreover, the main salinity peaks of the two salinity trajectories are located at different wheat growth stages. S3: During the process of decreasing salinity in the root zone, the recovery stage is determined, and the newly formed tillers in the recovery stage are identified as recovery source tillers and their source is marked; after the salinity in the root zone rises again, the recovery source tillers are tracked until maturity to obtain the number of recovery source tillers, the number of effective ears formed by recovery source tillers, and the corresponding recovery source grain yield, and the total grain yield of the corresponding wheat candidate family is obtained; S4: Determine the proportion of ears formed from the recovery source based on the number of tillers and the number of effective ears; determine the contribution ratio of the recovery source yield based on the grain yield and total grain yield of the recovery source; determine the selection criteria based on the proportion of ears formed from the recovery source and the contribution ratio of the recovery source yield of the salt-tolerant control material in the same period and the total grain yield of the high-yield control material in the same period; retain wheat candidate families that meet the selection criteria under both the first and second salt trajectories. S5: For the retained wheat candidate families, compare their contribution ratio of recovery source yield under the two salinity trajectories, and determine the wheat growth stage at which the main salinity peak of the salinity trajectory with the lower contribution ratio of recovery source yield is located; when the contribution ratio of recovery source yield is the same under the two salinity trajectories, determine the restricted growth stage according to the recovery source grain yield under the two salinity trajectories, and retain the seed of the retained wheat candidate families respectively. S6: For wheat candidate families with a determined restricted fertility stage, the target cumulative effective salt exposure remains unchanged in the next segregation generation, the interval salt exposure in the non-restricted fertility stage is reduced, and the reduced interval salt exposure is added to the restricted fertility stage in equal amounts to form a reinforced salt trajectory; for wheat candidate families without a determined restricted fertility stage, the first and second salt trajectories continue to be used in the next segregation generation. Following steps S3 to S4, successive generations of screening were conducted, and wheat candidate families that met the selection criteria for two or more consecutive segregation generations were identified as high-yield and stress-resistant breeding materials for wheat in coastal saline-alkali lands.

[0022] In this embodiment, wheat segregating generation families in the continuous selection phase are used as wheat candidate families. By constructing two salt trajectories with similar cumulative salt exposure levels but major salt peaks at different growth stages, the source of recovery growth after salt damage and its contribution to final yield are traced, and the salt exposure sequence of the next segregating generation is adjusted according to the screening results.

[0023] In this embodiment, the specific salinity level, salt exposure, and yield selection limits are not fixed values ​​that are detached from the actual conditions of the experimental area. Instead, they are derived from the historical root zone salinity monitoring results of the target coastal saline-alkali land area, the actual performance of the control materials at the same time, and the actual screening results of the previous segregation generation, to ensure that different coastal saline-alkali land areas can be implemented according to the same technical logic.

[0024] Select representative coastal saline-alkali land as the target screening area, and obtain root zone soil salinity change data for at least one complete wheat growth cycle in the area before formally conducting breeding screening of candidate families.

[0025] In this embodiment, the soil electrical conductivity of the root zone is used to characterize the salinity of the root zone. The root zone soil layer is determined based on the actual distribution range of the main wheat root system in the target area. Once determined, the same root zone soil layer is used as the salinity monitoring area for the first planting unit, the second planting unit, the salt-tolerant control material, the high-yield control material, and subsequent segregating generations in this round of experiments.

[0026] For the same round of screening, the historical root zone salinity data, the current round of experimental data, and the data from subsequent segregation generations all used the same conductivity measurement system. When using in-situ conductivity testing, the type of testing device, installation depth, and temperature compensation method remained consistent; when using soil sample extraction testing, the sampling depth, soil-to-water ratio, extraction method, and testing conditions remained consistent.

[0027] If historical data uses different measurement systems, representative soil samples from the target area are tested in parallel using both the historical and current measurement methods. A conversion relationship is established based on the corresponding results of the two methods, and the historical data is uniformly converted to the measurement system used in this round before subsequent calculations are performed.

[0028] To distinguish between actual salinity changes and detected fluctuations, the conductivity detection method used in this round was repeatedly measured to determine the fluctuation range of the repeated measurements under the same conditions. Subsequent adjacent measurement results were considered to indicate stable salinity in the root zone only if the changes exceeded this fluctuation range; only when the changes exceeded this fluctuation range were they considered to have resulted in an effective increase or decrease.

[0029] Therefore, in this embodiment, the subsequent determinations of salt increase, salt decrease, and initial salt content of the two planting units are based on the repeatability of the actual detection method, rather than artificially setting a fixed conductivity difference.

[0030] Using only the highest conductivity at a certain moment cannot reflect the actual salt effects experienced by wheat throughout its growth process. Therefore, this embodiment also considers the degree and duration of the salt content in the root zone exceeding the baseline salt content.

[0031] The soil electrical conductivity of the root zone was obtained chronologically throughout a complete wheat growth cycle. The soil electrical conductivity of the root zone prior to the formation of the salinity trajectory was used as the initial root zone salinity.

[0032] For any two adjacent monitoring times, when the soil electrical conductivity in the root zone is higher than the initial root zone salinity, the interval salt exposure of the monitoring interval is determined according to the increase in salinity between the two monitoring times relative to the initial root zone salinity and the duration between them.

[0033] The interval salt exposure is determined using the following formula: ; In the formula, For the first Inter-regional salt exposure levels in each monitoring interval; and These represent the effective increase in soil electrical conductivity in the root zone relative to the initial salinity at the start and end times of the monitoring interval, respectively. This represents the actual duration of the monitoring interval.

[0034] When the soil electrical conductivity in the root zone is not higher than the initial salinity in the root zone, the corresponding effective increase is treated as zero, and no negative salt exposure is formed.

[0035] The cumulative effective salt exposure for a complete wheat growth cycle is obtained by summing up the salt exposure levels in each interval.

[0036] When the target coastal saline-alkali area has only one complete reproductive cycle of valid historical data, the cumulative effective salt exposure calculated for that reproductive cycle is used as the target cumulative effective salt exposure. When there is data for two or more complete reproductive cycles, the cumulative effective salt exposure for each reproductive cycle is calculated separately, and the median value that can characterize the normal salt exposure level of the area is used as the target cumulative effective salt exposure.

[0037] The target cumulative effective salt exposure thus obtained comes from the actual salt content changes experienced by the target coastal saline-alkali area, rather than from artificially selecting a fixed NaCl concentration or a fixed EC value.

[0038] Select candidate wheat families from the same segregation generation, and randomly divide the seeds of each candidate wheat family into a first seed group and a second seed group. The first seed group is sown in the first planting unit, and the second seed group is sown in the second planting unit.

[0039] The sowing time, sowing density, basic fertilization method and conventional field management methods of the two planting units were kept consistent, and the evaluation area of ​​the same size was set up.

[0040] For each wheat candidate family, a unique family number is established, and its specific planting location in the first and second planting units is recorded. When plant-by-plant tracking is required, plant location numbers are further set under the family number.

[0041] Before the formation of salinity tracks, the initial root zone soil electrical conductivity of the first and second planting units was measured.

[0042] When the difference between the two is within the fluctuation range of repeated measurements of the aforementioned detection method, the two planting units are considered to have comparable initial root zone salinity. If it exceeds this range, the basic salinity is adjusted by rinsing with fresh water or by supplementing with saline solution that is compatible with the salinity composition of the target area, and the two planting units are retested until they reach a comparable state.

[0043] This avoids the fact that the difference between the first and second salinity trajectories actually stems from the difference in initial salinity.

[0044] Before the experiment began, two different wheat growth stages were determined based on the actual salt return patterns in the target coastal saline-alkali area, serving as the main peak salt levels for the first and second salt paths, respectively.

[0045] The wheat growth stages are determined based on the actual morphological development of the plant, rather than solely on the number of days since sowing. For example, the tillering stage can be determined by the appearance of identifiable tillers at the base of the main stem, the jointing stage by the obvious elongation of the internodes of the main stem, and the heading stage by the swelling of the flag leaf sheath and the development of the young spikelets.

[0046] The same criteria for determining the growth stage were used for the first planting unit, the second planting unit, the wheat candidate family, and the control materials in the same round of screening.

[0047] The two main salt peak target stages are determined before the start of the experiment. After candidate families enter the screening process, the reproductive stage corresponding to the main salt peak is not temporarily changed based on the actual growth of a particular family.

[0048] Both the first and second planting units used the already determined cumulative effective salt exposure as the salt exposure control benchmark for the entire wheat growth cycle.

[0049] By adjusting the timing of saline ingress into the root zone and the timing of freshwater leaching and drainage, the salt exposure levels between the first and second planting units were allocated to different wheat growth stages.

[0050] When it is necessary to increase the salinity of the root zone, saline solution with a composition of main soluble salts adapted to the target coastal saline-alkali area is introduced in stages. After each introduction, the soil electrical conductivity of the root zone is measured, and the cumulative effective salt exposure is updated based on the measured results. When it is necessary to reduce the salinity of the root zone, the salinity of the root zone is reduced by rinsing with fresh water and drainage.

[0051] The amount of saline water input or freshwater leaching is not used as a basis for determining whether a salt trajectory has formed. Ultimately, the determination is based on the actual measured soil electrical conductivity in the root zone and the salt exposure amount obtained from it.

[0052] Through the above methods, the first and second planting units achieve the same cumulative effective salt exposure level throughout the entire growth cycle, while the maximum root zone soil electrical conductivity of the two units occurs at different wheat growth stages, thus forming the first and second salt trajectories.

[0053] Each effective salinity trajectory includes the main salinity peak, the salinity decrease in the root zone after the main salinity peak, and the salinity increase in the root zone after the decrease.

[0054] When a planting unit has two equally significant salt peaks that cannot be distinguished based on the detection accuracy, and the growth stage of the unique significant salt peak cannot be determined, the data from that planting unit in this round will not be used for candidate family screening.

[0055] Therefore, the main difference between the first and second salinity trajectories is the timing and location of salt exposure, rather than simply forming a conventional salt concentration gradient with high salt on one side and low salt on the other.

[0056] After the main salinity peaks of the first and second salinity trajectories appear, the soil electrical conductivity in the root zone will continue to be obtained using a fixed monitoring method.

[0057] When the soil electrical conductivity in the root zone decreases sequentially at three consecutive monitoring times, and the decrease between two adjacent times exceeds the fluctuation range of repeated measurements of the aforementioned detection method, the salinity in the root zone is considered to have entered a continuous decreasing process.

[0058] The monitoring interval between the first two of the three monitoring times is determined as the starting interval of the recovery phase.

[0059] If there is only one decrease followed by an increase, or if the decrease is still within the detection fluctuation range, the recovery phase should not be determined based on this, and monitoring should continue.

[0060] Therefore, the recovery phase is determined based on the actual decrease in salinity in the root zone environment of the candidate family, rather than arbitrarily defining the day after the salt treatment as the recovery phase.

[0061] In the initial phase of the recovery stage, the main stems and tillers that have already formed within the evaluation area of ​​each wheat candidate family are initially identified.

[0062] Initial identification uses a base numbering ring, weather-resistant marking strip, or other sustainable physical identifier that does not hinder the normal growth of the plant.

[0063] After the initial interval of the recovery phase, newly formed tillers that do not have the initial identifier are identified as recovery source tillers.

[0064] Each restored tiller is assigned an independent source identifier, which is able to identify at least the wheat candidate family, the specific plant and the tiller number on that plant.

[0065] This establishes a continuous lineage relationship between wheat candidate families, plants, and restored tillers.

[0066] Once a restored source tiller is formed and its source identification is completed, it is included in the number of restored source tillers.

[0067] Even if the tiller from the restored source dies, degenerates, or fails to form an effective ear during the subsequent rise in salinity, it will not be removed from the number of tillers from the restored source, thus avoiding the overestimation of the ear formation results from the restored source by only counting surviving tillers at maturity.

[0068] Continue to monitor the electrical conductivity of the root zone soil during the recovery phase.

[0069] When the soil electrical conductivity in the root zone increases sequentially over three consecutive monitoring times, and the increase between adjacent monitoring times exceeds the fluctuation range of repeated measurements of the detection method, it is determined that the salinity in the root zone has increased again.

[0070] After the re-increase is confirmed, the source identifier of the regenerated tillers is maintained until maturity.

[0071] In this embodiment, the subsequent evaluation targets are always the same batch of regenerated tillers that formed after the previous major salinity peak ended and the salinity in the root zone decreased, rather than re-counting all tillers at maturity.

[0072] During the maturity stage, the final state of the restored tillers is confirmed one by one according to the source identifier.

[0073] In this embodiment, an effective ear refers to an ear whose corresponding tiller can be identified by its source identifier and which actually forms at least one harvestable grain at maturity.

[0074] Empty ears that have not formed grains, as well as tillers that die before maturity and have not formed complete ears, are not counted in the number of effective ears, but are still counted in the number of tillers from the source of recovery.

[0075] The number of restorer tillers and the number of effective ears formed by restorer tillers were counted for each candidate family, and the ratio of the two was used as the restorer ear formation ratio.

[0076] Further, based on the source identification, the effective ears formed by the tillers of the restored source are harvested and threshed separately to obtain the grain yield of the restored source; at the same time, the total grain yield of all effective ears formed in the same evaluation area of ​​the candidate family is obtained.

[0077] The same cleaning, drying, and weighing conditions were used for both the source grains and all grains to make them comparable.

[0078] The contribution ratio of production from restored sources is determined according to the following formula: In the formula, To restore the contribution ratio of source production; To restore the effective ear yield corresponding to the restored source tiller; The total grain yield is the total yield of all effective ears formed within the same candidate family and the same evaluation area.

[0079] The yield contribution ratio of the recovery source is used to reflect how much of the final grain yield of the candidate family comes from the recovery source tillers that re-formed after salt damage and experienced another increase in salinity.

[0080] When a candidate family fails to produce harvestable grains under a certain salinity profile, i.e., the total grain yield is zero, the contribution ratio of the recovery source yield is no longer calculated, and the candidate family is directly determined not to have met the high-yield selection criteria under that salinity profile.

[0081] This avoids ambiguity in calculation and judgment caused by a denominator of zero.

[0082] Salt-tolerant and high-yield control materials were determined before the candidate families officially entered this round of screening.

[0083] Salt-tolerant control materials are determined based on existing records of salt tolerance performance from regional trials, breeding trials, or production and planting evaluations in the target coastal saline-alkali areas. They should have an existing evaluation basis for maintaining normal ear formation and grain filling under saline-alkali conditions in the target area.

[0084] High-yield control materials are determined based on existing regional yield trials, breeding trials, or production and planting records in the target area, and should have stable yield performance in the local area.

[0085] Once the control materials are determined, they will not be replaced based on the performance of the candidate families after the results of this round of candidate family trials are produced.

[0086] The first and second planting units were planted simultaneously with salt-tolerant control materials and high-yield control materials from the same source, and were subjected to the corresponding first and second salinity trajectories, respectively.

[0087] Salt-tolerant control materials were identified in the same way as candidate families to determine the recovery stage, identify recovery source tillers, track effective panicles from the recovery source, and obtain the yield contribution ratio of the recovery source.

[0088] When the control material has two or more effective replicates, the arithmetic mean of the results of each effective replicate is used as the control evaluation value under the salinity trajectory.

[0089] Invalid duplicates caused by mechanical damage, severe non-target pests and diseases, or irrigation and drainage facility malfunctions will not be included in the average calculation, and the reasons for exclusion will be retained.

[0090] Selection conditions are formed under the first salinity trajectory and the second salinity trajectory, respectively.

[0091] The proportion of ears produced from the recovery source in the salt-tolerant control material at the corresponding salt concentration trajectory was used as the selection threshold for ear formation. The proportion of the recovery source yield contribution of the salt-tolerant control material at the corresponding salt concentration trajectory was used as the selection limit for recovery yield. The total grain yield of the high-yield control material under the corresponding salinity trajectory was used as the high-yield selection threshold.

[0092] Therefore, the three selection limits were all derived from the control materials planted in the same period of this round, rather than from a fixed percentage pre-specified in the instructions.

[0093] For each wheat candidate family, if the proportion of ears formed from the recovery source is not lower than the ear formation selection threshold, the proportion of yield contribution from the recovery source is not lower than the yield recovery selection threshold, and the total grain yield is not lower than the high-yield selection threshold under the current salinity trajectory, then the candidate family is deemed to have met the selection criteria under the salinity trajectory.

[0094] The same wheat candidate family must meet the above selection criteria under both the first and second salinity trajectories to be retained.

[0095] If the selection criteria are met only under one of the salinity profiles, the wheat family will not be retained in this round of selection.

[0096] This allows us to exclude stage-escape materials that perform well because their reproductive period happens to avoid specific salt peaks.

[0097] For wheat candidate families that meet the selection criteria under both the first and second salinity trajectories, compare their contribution ratio of yield recovery sources under the two salinity trajectories.

[0098] The low contribution of salt to the yield of recovery sources indicates that when the main salt peak is located in the growth stage corresponding to the salt trajectory, the conversion of recovery tillers formed after salt damage into final grain yield is more significantly restricted. Therefore, the wheat growth stage where the main salt peak of the salt trajectory is located is identified as the growth restriction stage.

[0099] When the contribution ratio of the recovery source yield under the two salinity trajectories is the same after processing according to the unified data recording accuracy of this round, the recovery source grain yield under the two salinity trajectories is compared, and the main salinity peak growth stage corresponding to the one with lower recovery source grain yield is determined as the restricted growth stage.

[0100] When the contribution ratio of the restored source of production and the grain production of the restored source are the same, the candidate family is recorded as a retained family with no determined stage of reproductive restriction without artificially designating a stage of reproductive restriction.

[0101] The accuracy of data recording in this round was uniformly determined before the experimental data was generated. All candidate families and control materials adopted the same data retention rules to avoid artificially adjusting the decimal places based on the results of a certain family to obtain the stage of restricted reproduction.

[0102] For wheat candidate families that have been identified as being in the restricted reproductive stage, seed will be retained to establish the next segregation generation.

[0103] The next segregation generation will continue to use the target cumulative effective salt exposure determined by the previous segregation generation, without increasing the total salt exposure borne by wheat throughout its entire growth cycle.

[0104] Based on the comparison of the two salt trajectories of the previous segregation generation, the salt exposure level that needs to be shifted from the unrestricted fertility stage to the restricted fertility stage is determined.

[0105] In practice, the transfer intensity can be determined based on the difference in the proportion of the yield contribution from the recovery source between the two salt trajectories; when the proportions of the yield contribution from the two recovery sources are the same but the grain yields from the recovery sources are different, the transfer intensity can be determined based on the difference in the grain yields from the recovery sources.

[0106] The intensity of migration here is determined by the actual performance of the candidate families in the previous segregation generation, rather than by a fixed proportion uniformly adopted by all candidate families.

[0107] During the non-restricted reproductive period, each monitoring interval with a salt exposure level greater than zero was first identified and then sorted in descending order of salt exposure level.

[0108] Start by reducing salt exposure in the monitoring interval with the highest salt exposure; when that interval can provide all the salt exposure that needs to be transferred, reduce only that interval; if it is insufficient, reduce from the next monitoring interval in sequence until the cumulative reduction reaches the salt exposure that needs to be transferred.

[0109] The reduced salt exposure is increased in equal amounts to the fertility restriction stage.

[0110] The increase in the fertility restriction stage is achieved through a phased adjustment method, rather than by increasing the salt concentration all at once to create an instantaneous salt peak that is out of touch with the actual conditions of the target coastal saline-alkali area.

[0111] After each adjustment, the soil electrical conductivity in the root zone was retested, and the actual salt exposure in the resulting zone was re-determined based on the measured values.

[0112] The increased salt exposure that can be achieved during the fertility restriction period is also constrained by historical monitoring data of the target coastal saline-alkali area, that is, the resulting salinity status should not deviate from the range of existing actual salinity changes in the area.

[0113] If the amount of salt exposure to be transferred, calculated based on the differences in the previous generation, exceeds the increase that the fertility-restricting stage can actually accommodate, then the increase that the fertility-restricting stage can actually generate will be used as the final amount to be transferred.

[0114] Therefore, the next segregation generation reinforces the weak reproductive stage exposed by the previous segregation generation, rather than amplifying the stress by infinitely increasing salt concentration.

[0115] For candidate families that have been identified as being in the restricted reproductive stage, the next segregation generation will still divide the seeds of the same family into two corresponding seed groups and allocate them to two planting units respectively.

[0116] One of the planting units used a salt trajectory without salt exposure time-series redistribution as a reference salt trajectory.

[0117] Another planting unit, based on the restricted fertility stage determined by the previous segregation generation, increases the amount of salt exposure reduced in the non-restricted fertility stage to the restricted fertility stage in an equal amount, thus forming an enhanced salt exposure trajectory.

[0118] The same target cumulative effective salt exposure was used for both the reference salt trajectory and the enhanced salt trajectory over a complete wheat growth cycle.

[0119] Therefore, the next segregation generation is not simply a comparison of lower and higher salinity, but rather a comparison of the performance of candidate families in the face of normal salt exposure time series and salt exposure time series enhanced for their own reproductive restriction stage, while keeping the overall salt exposure level constant.

[0120] Subsequently, the recovery stage was determined using the aforementioned method. The source tillers of the recovery were identified, and after the salinity increased again, they were tracked to maturity to obtain the proportion of ears formed from the recovery source, the grain yield from the recovery source, the proportion of yield contribution from the recovery source, and the total grain yield.

[0121] The next separation generation will continue to include salt-tolerant control materials and high-yield control materials, and the corresponding selection limits will be formed in the same manner.

[0122] Candidate families will only be retained if they meet the selection criteria under both the reference salinity trajectory and the enhanced salinity trajectory.

[0123] For wheat candidate families whose reproductive restriction stage was not determined in the previous segregation generation, the next segregation generation will not artificially create a salt-enhancing trajectory, but will continue to use the first and second salt-enhancing trajectories for dual-trajectory screening.

[0124] Families that still meet the selection criteria after the next generation of separation screening will continue to be propagated separately.

[0125] Wheat candidate families that meet the corresponding dual-track selection criteria for two or more consecutive segregation generations are identified as high-yield and stress-resistant breeding materials for wheat in coastal saline-alkali lands.

[0126] For families that have been identified as being in a restricted fertility phase, continuously meeting the selection criteria means that the previous segregation generation met the selection criteria under both the first and second salinity trajectories, and the next segregation generation met the selection criteria under both the reference salinity trajectories and the reinforced salinity trajectories.

[0127] For families whose reproductive restriction stage has not been determined, the selection criteria must be met under both the first and second salinity trajectories used in consecutive segregation generations.

[0128] This avoids directly identifying materials that perform well by chance in a particular generation as stress-resistant and high-yielding breeding materials.

[0129] Traditional salt tolerance screening methods often involve treating materials with different salt concentrations and then evaluating them based on survival rate, number of tillers, plant height, or final yield. However, when different materials exhibit different growth processes, the same natural salt return process may occur during the salt-tolerant stage of one material while another is in the salt-sensitive stage. This could lead to the misclassification of materials that avoid the salt peak as salt-tolerant.

[0130] This implementation method does not simply increase the salt concentration, but rather arranges the same wheat candidate family in two planting units, so that the main salt peaks fall at different wheat growth stages while keeping the total cumulative effective salt exposure of the two planting units comparable.

[0131] After the main salt concentration peak ends, instead of simply recording the total number of tillers at maturity, the recovery phase is determined when the salt concentration in the root zone actually begins to decline, and source identifiers are established for each newly formed recovery tiller thereafter.

[0132] Therefore, it is possible to further determine whether the tillers from this batch of restored sources formed effective ears and how many actual grains were produced after the salinity in the root zone increased again.

[0133] Further differentiation can be achieved by restoring the contribution ratio of production from different sources: One type has a higher final total yield, but the yield mainly comes from the main stem and tillers that have formed before the main salt concentration peak; Another type is the ability to regenerate tillers after the stress caused by the main salt peak, and to allow these tillers to continue to form effective ears and grains after experiencing another increase in salt content.

[0134] This method focuses on preserving the latter type of families that possess genuine resilience to adversity and the ability to generate yields after recovery.

[0135] Based on this, the reproductive restriction stage is identified by the difference in the contribution of the recovery source to the yield of the same candidate family during the two major salinity peaks, and the results are fed back to the next segregation generation.

[0136] The next segregation generation will maintain the overall target cumulative effective salt exposure unchanged, but will only redistribute a portion of the salt exposure from the non-restricted fertility stage to the restricted fertility stage, and will be screened again by referring to the salt exposure trajectory and the enhanced salt exposure trajectory.

[0137] This leads to: The technology chain includes pairing of two planting units of the same lineage, equal cumulative salt exposure, different salt peak timing, recovery stage identification, tracing of tillers from the recovery source, ear formation and grain formation after salt concentration rises again, joint selection of dual salt trajectories, determination of the growth restriction stage, redistribution of salt exposure timing in the next segregating generation, and successive screening based on salt trajectory and enhanced salt trajectory.

[0138] Among them, the target cumulative effective salt exposure is derived from historical measured data of the target coastal saline-alkali area; the salt content change is determined based on the actual root zone soil electrical conductivity; the ear formation status of the restored source and the yield contribution of the restored source are derived from the source tracing results; the selection boundary is derived from the control materials of the same period; the fertility restriction stage is derived from the actual comparison results of two salt trajectories of the same family; the enhancement location and salt exposure transfer of the next segregation generation are derived from the screening results of the previous segregation generation.

[0139] Therefore, each key step has a clear data source and sequential relationship, and it does not require the artificial setting of unsourced fixed salt concentrations, recovery thresholds, yield weights, or comprehensive scoring parameters to be implemented.

[0140] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land, characterized in that, Includes the following steps: S1: All wheat candidate families of the same segregating generation are assigned to the first planting unit and the second planting unit respectively, and the correspondence between the same wheat candidate family and the two planting units is established. S2: Monitor the changes in wheat root zone salinity in two planting units as the growth process progresses. Determine the cumulative effective salt exposure based on the increase in root zone salinity relative to the initial root zone salinity and the corresponding duration. Form a first salinity trajectory and a second salinity trajectory according to the same target cumulative effective salt exposure. Both the first and second salinity trajectories include the main salinity peak, the root zone salinity decrease process after the main salinity peak, and the re-increase process after the root zone salinity decreases. Moreover, the main salinity peaks of the two salinity trajectories are located at different wheat growth stages. S3: During the process of decreasing salinity in the root zone, the recovery stage is determined, and the newly formed tillers in the recovery stage are identified as recovery source tillers and their source is marked; after the salinity in the root zone rises again, the recovery source tillers are tracked until maturity to obtain the number of recovery source tillers, the number of effective ears formed by recovery source tillers, and the corresponding recovery source grain yield, and the total grain yield of the corresponding wheat candidate family is obtained; S4: Determine the proportion of ears formed from the recovery source based on the number of tillers and the number of effective ears from the recovery source; determine the yield contribution ratio of the recovery source based on the grain yield of the recovery source and the total grain yield. Selection criteria were determined based on the proportion of ears formed from the recovery source and the proportion of yield contribution from the recovery source in the salt-tolerant control material during the same period, as well as the total grain yield of the high-yielding control material during the same period. Wheat candidate families that met the selection criteria under both the first and second salt trajectories were retained. S5: For the retained wheat candidate families, compare their contribution ratio of recovery source yield under the two salinity trajectories, and determine the wheat growth stage at which the main salinity peak of the salinity trajectory with the lower contribution ratio of recovery source yield is located; when the contribution ratio of recovery source yield is the same under the two salinity trajectories, determine the restricted growth stage according to the recovery source grain yield under the two salinity trajectories, and retain the seed of the retained wheat candidate families respectively. S6: For wheat candidate families with a determined restricted fertility stage, the target cumulative effective salt exposure remains unchanged in the next segregation generation, the interval salt exposure in the non-restricted fertility stage is reduced, and the reduced interval salt exposure is added to the restricted fertility stage in equal amounts to form a reinforced salt trajectory; for wheat candidate families without a determined restricted fertility stage, the first and second salt trajectories continue to be used in the next segregation generation. Following steps S3 to S4, successive generations of screening were conducted, and wheat candidate families that met the selection criteria for two or more consecutive segregation generations were identified as high-yield and stress-resistant breeding materials for wheat in coastal saline-alkali lands.

2. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 1, characterized in that, In step S1, the seeds of each generation of each wheat candidate family are divided into a first seed group and a second seed group, and sown in the first planting unit and the second planting unit respectively. The two planting units used the same sowing time, sowing density and basic cultivation conditions, and the planting positions of the first seed group and the second seed group were recorded according to the wheat candidate family number and plant position to maintain the correspondence of the same wheat candidate family under the first salinity trajectory and the second salinity trajectory.

3. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 2, characterized in that, In step S2, the soil electrical conductivity of the wheat root zone is used to characterize the salinity of the root zone, and the soil electrical conductivity of the root zone before the formation of the salinity trajectory is used as the initial salinity of the root zone. For each monitoring interval where the root zone soil conductivity is higher than the initial root zone salinity, the increase in root zone soil conductivity relative to the initial root zone salinity at the start and end times of the monitoring interval is obtained. The product of the average of the two increases and the duration of the monitoring interval is taken as the interval salt exposure. The cumulative effective salt exposure is obtained by accumulating the salt exposure of each interval.

4. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 3, characterized in that, In step S2, the historical root zone soil electrical conductivity monitoring data of at least one complete wheat growth cycle in the target coastal saline-alkali area are processed according to the same method as in step S2 to obtain the target cumulative effective salt exposure. By adjusting the saline water input period and freshwater leaching period of the first and second planting units, the salt exposure of each wheat growth stage is changed, so that the two planting units can reach the target cumulative effective salt exposure, and the period when the soil electrical conductivity of their respective root zones is at its maximum corresponds to different wheat growth stages.

5. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 4, characterized in that, In step S3, after the main salt peak appears, the root zone soil electrical conductivity is continuously acquired at the same monitoring interval. When the root zone soil electrical conductivity acquired at three consecutive monitoring times decreases sequentially, the monitoring interval between the first two monitoring times is determined as the starting interval of the recovery phase. Initially identify the main stems and tillers that have already formed in the initial interval. Tillers that form after the initial interval and do not have initial identification are identified as recovery source tillers. Establish source identification between each recovery source tiller and the corresponding wheat candidate family number and plant position.

6. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 5, characterized in that, In step S3, during the recovery phase, the soil electrical conductivity in the root zone is continuously acquired at monitoring intervals. When the soil electrical conductivity in the root zone increases sequentially at three consecutive monitoring times, it is determined that the salinity in the root zone has increased again. After the salinity in the root zone increases again, the source identifiers of each restored tiller are maintained until maturity. Based on the source identifiers, the number of restored tillers, the number of effective ears formed by restored tillers, and the grain quality formed by effective ears are counted. At the same time, the grain quality formed by all effective ears of the corresponding wheat candidate families is counted.

7. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 6, characterized in that, In step S4, the ratio of the number of effective ears formed by the tillers from the restoration source to the number of tillers from the restoration source is determined as the ear formation ratio from the restoration source; the grain quality corresponding to the effective ears formed by the tillers from the restoration source is determined as the grain yield from the restoration source; and the ratio of the grain yield from the restoration source to the total grain yield formed by all effective ears of the corresponding wheat candidate line is determined as the yield contribution ratio from the restoration source.

8. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 7, characterized in that, In step S4, salt-tolerant control material and high-yield control material are planted simultaneously in the first planting unit and the second planting unit, respectively. For each salt content trajectory, the proportion of ears formed from the recovery source of the salt-tolerant control material was used as the selection limit for ears formed, the proportion of yield contribution from the recovery source of the salt-tolerant control material was used as the selection limit for yield recovery, and the total grain yield of the high-yield control material was used as the selection limit for high yield. When the proportion of ears formed from the recovery source of a wheat candidate family is not lower than the ear-forming selection threshold, the proportion of yield contribution from the recovery source is not lower than the yield recovery selection threshold, and the total grain yield is not lower than the high-yield selection threshold, the wheat candidate family is deemed to have met the selection criteria under the salinity trajectory.

9. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 8, characterized in that, In step S5, when the contribution ratio of the recovery source yield under the first salt trajectory and the second salt trajectory is different, the wheat growth stage corresponding to the main salt peak of the lower recovery source yield contribution ratio is determined as the restricted growth stage. When the contribution ratio of the recovery source yield is the same under the two salt trajectories, the wheat growth stage at which the main salt peak corresponding to the lower recovery source grain yield is located is determined as the growth restriction stage. When the contribution ratio of recovery source yield and the recovery source grain yield are the same under both salinity trajectories, the stage of restricted fertility is uncertain.

10. The method for screening stress-resistant and high-yielding wheat breeding materials in coastal saline-alkali land according to claim 9, characterized in that, In step S6, for wheat candidate families with a restricted reproductive stage, the salt exposure of at least one interval in the previous segregating generation that is in the unrestricted reproductive stage is determined, and the salt exposure of the interval is reduced in the next segregating generation. The reduction is increased to the salt exposure of the interval corresponding to the restricted reproductive stage, so that the sum of the salt exposure of each interval in the next segregating generation is consistent with the target cumulative effective salt exposure. For wheat candidate families whose reproductive stage has not been determined, the distribution pattern of salt exposure between the first and second salt trajectories in the next segregation generation remains unchanged.

Images