Saline-alkali land remediation method based on simultaneous activation of leymus chinensis rhizome and sexual complementary sowing in different layers

Abstract

The method for saline-alkali land remediation based on simultaneous activation of Leymus chinensis rhizome and sexual complementary sowing in different layers belongs to the technical field of ecological remediation and sustainable utilization of grassland. The method solves the technical problem that there is currently a lack of a collaborative remediation technology that can combine low disturbance, activation of the original Leymus chinensis vegetative propagation potential, and efficient introduction of sexual reproduction. The method comprises the following steps: S1, determining a saline-alkali region that needs to be remediated; S2, determining a time window for remediation operation; S3, implementing narrow-width low-disturbance deep ploughing, and leaving a width between adjacent deep ploughing strips that is greater than the width of the deep ploughing narrow strips; S4, implementing in-situ collaborative seeding and directional root induction, and synchronously implementing precision seeding, positioning fertilization and habitat directional induction in the narrow strips where deep ploughing is completed by using a mechanical linkage device; and S5, field management.

Description

Technical Field

[0001] This invention belongs to the field of ecological restoration and sustainable grassland utilization technology, specifically involving a method for the restoration of saline-alkali land based on simultaneous heterogeneous layering of Leymus chinensis root and rhizome activation and sexual reseeding. Background Technology

[0002] Due to the combined effects of human activities, natural conditions, and global change, the Songnen Plain suffers from severe salinization and degradation. As salinization intensifies, the relative biomass of high-quality forage grasses declines rapidly, and their cover decreases. Intense evaporation causes soluble salts in the soil to rise to the surface via capillary water, exacerbating soil salinization. Species with low salt tolerance gradually decrease, while those with higher tolerance (such as *Suaeda salsa*, *Salvia splendens*, *Kochia scoparia*, and *Suaeda salsa*) rapidly occupy habitats, forming mixed or dominant salt-tolerant plant communities. With increasing salinity, large areas of salt-alkali efflorescence even appear, and the original sheepgrass-dominated grassland habitat continues to fragment and disappear. Therefore, the Songnen Plain has become one of the most important areas of soda-alkali soil distribution in my country and even the world, with significant spatial variations in soil salinization. This poses a serious obstacle to grassland restoration and saline-alkali land ecological management, and the contradiction between grassland salinization and livestock development is becoming increasingly prominent.

[0003] Leymus chinensis, a perennial xerophytic to mesoproterophytic rhizomatous grass belonging to the genus Leymus in the family Poaceae, is mainly distributed in eastern Eurasia. It is an important forage resource in northern my country and was the original dominant vegetation of the Songnen Grassland. High in crude protein and palatable, it is known as the "King of Grasses." In natural grassland ecosystems, Leymus chinensis primarily reproduces asexually, relying on its strong rhizome propagation ability for reproduction and vegetation renewal. However, in recent years, with the increasing degradation of grasslands and soil salinization, Leymus chinensis grasslands have shown a significant trend of degradation, with decreasing area, shorter plants, and reduced biomass.

[0004] Under field conditions, the germination rate, seed setting rate, and seedling emergence rate of Leymus chinensis seeds are relatively low, resulting in a severe shortage of seed production, especially for ecological restoration. Meanwhile, Leymus chinensis breeding in my country faces bottlenecks such as a limited number of approved varieties, low seed yield, slow propagation speed, and outdated breeding techniques. For moderately to severely degraded grasslands, existing ecological restoration technologies mostly focus on comprehensive soil improvement and transplanting of improved varieties or widespread sowing. For example, the Chinese invention patent application "A method for rapid restoration of top-level vegetation using Leymus chinensis patches in situ to treat alkaline patches" (publication number CN104541642A) provides a comprehensive method for restoring saline-alkali land by combining comprehensive soil improvement and transplanting of improved varieties.

[0005] However, for mildly to moderately degraded natural grasslands that still retain a certain proportion of native Leymus chinensis, comprehensive restoration methods involving excessive disturbance are costly and cause significant ecological damage. Currently, there is a lack of a synergistic restoration technology that can combine low-disturbance restoration, activate the asexual propagation potential of native Leymus chinensis, and efficiently introduce sexual reproduction. Summary of the Invention

[0006] To address the current lack of a synergistic remediation technology that combines low-disturbance activation of the asexual propagation potential of native Leymus chinensis with efficient introduction of sexual reproduction, this invention provides a method for remediating saline-alkali land based on simultaneous and heterogeneous activation of Leymus chinensis rhizomes and sexual reseeding.

[0007] The method includes the following steps:

[0008] S1. Identify the saline-alkali land areas that need restoration;

[0009] S2. Determine the time window for carrying out repair work;

[0010] S3. Implement narrow-span, low-disturbance deep tillage, with the width between adjacent deep tillage strips being greater than the width of the narrow deep tillage strip;

[0011] S4. Implement in-situ coordinated reseeding and directional root introduction of seeds. Within the narrow strips where deep loosening has been completed, use mechanical linkage devices to simultaneously implement precision sowing, fixed-position fertilization and habitat directional induction.

[0012] S5. Field management.

[0013] Furthermore, when identifying the saline-alkali land areas that need restoration, the areas that need restoration are characterized by the native Leymus chinensis population being in a natural degradation stage due to physiological aging, with the community characteristics being: Leymus chinensis coverage of 20-50%, and accompanied by salt-tolerant plants.

[0014] Furthermore, the time window for restoration work is within a limited time frame each year, after the soil thaws and before or after the sheepgrass turns green again, and before other species have turned green and sprouted.

[0015] Furthermore, when implementing narrow-span, low-disturbance deep tillage, the deep tillage depth is 15-20cm, the width of the narrow deep tillage strip is 15-30cm, and an undisturbed area with a width of 50-70cm is retained between adjacent deep tillage strips.

[0016] Furthermore, step S4 specifically involves: placing Leymus chinensis seeds in a shallow soil layer of 1-2 cm in the axial area of ​​the vertical projection of the deep loosening furrow, with a sowing rate of 2-3 kg / mu; simultaneously, placing fertilizer at a location 9-13 cm directly below the seeds, with the fertilizer placement area forming a nutrient core, inducing the expansion of the original rhizomes to reside and grow horizontally in the deep soil layer of 10-15 cm within the deep loosening furrow, thereby constructing a spatially displaced synchronous heterogeneous distribution structure with the root system of the re-sown seedlings distributed in the shallow soil layer of 1-5 cm.

[0017] Furthermore, specific field management measures include: from sowing to the seedling stage of Leymus chinensis, drip irrigation or sprinkler irrigation should be carried out on the sowing area according to rainfall conditions to ensure the germination of Leymus chinensis seeds and the establishment of seedlings, and to prevent grazing in the first year.

[0018] The beneficial effects of the method described in this invention are as follows:

[0019] This invention is applicable to mildly to moderately degraded natural grasslands that still retain a certain proportion of native Leymus chinensis. The core innovation lies in implementing low-disturbance operations within a precise time window: after soil thawing, before and after Leymus chinensis regrowth, and before other species have regrowth and emerged, minimizing ecological damage to non-target species. Through the physical channels created by narrow-width deep loosening and the nutrient core constructed by precise fertilization, the nutrient-seeding propagation of native rhizomes and the in-situ planting of reseeded seeds are simultaneously activated. Through the spatial dislocation mechanism of shallow sexual individuals occupying space and deep asexual rhizomes expanding, the invention fundamentally solves the problems of low efficiency and intense nutrient competition associated with single mechanisms in traditional restoration methods. It provides a new method that differs from existing ecological restoration technologies, which often focus on comprehensive soil improvement and transplanting of improved varieties or widespread sowing. This method offers minimal ecological disturbance, simple operation, synergistic dual-mechanism approach, and high Leymus chinensis recovery efficiency. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method described in an embodiment of the present invention;

[0021] Figure 2 This is a scenario diagram of narrow-span, low-disturbance deep tillage operation in an embodiment of the present invention (before the sheepgrass turns green in April 2025).

[0022] Figure 3 This is a field landscape image of Leymus chinensis after sexual reproduction was introduced in an embodiment of the present invention.

[0023] Figure 4 This is a landscape image showing the seedling emergence of Leymus chinensis after sowing in an embodiment of the present invention.

[0024] Figure 5 This is a community landscape image showing the coordinated restoration of grassland vegetation four months after the implementation of the restoration technology in this embodiment of the invention. Detailed Implementation

[0025] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0026] Example 1

[0027] This embodiment provides a method for the remediation of saline-alkali land based on simultaneous heterogeneous reseeding of Leymus chinensis rhizomes and sexual reseeding, enabling the asexual propagation and sexual reproduction of native Leymus chinensis, thereby rapidly and efficiently restoring Leymus chinensis vegetation. Figure 1 As shown, please follow these steps:

[0028] I. Location of Coupled Restoration Area and Assessment of Ecological Base. Moderately saline-alkali grasslands that have been continuously used for more than 8 years and have not undergone any treatment such as tilling or reseeding during this period were selected as restoration areas. The restoration areas are characterized by the native Leymus chinensis population being in a natural degradation stage due to physiological aging, with the following community characteristics: Leymus chinensis coverage of 20-50%, accompanied by salt-tolerant plants such as Imperata cylindrica and Scutellaria barbata.

[0029] The location of the restoration area combines the composition of surface vegetation and the activity status of underground rhizomes. The mildly or moderately degraded grassland has a high proportion of aging underground rhizomes and is in a state of growth stagnation after being used continuously for more than 8 years without human intervention.

[0030] II. Precise Time Window Limitation. The method is implemented within a limited time window each year, after the soil thaws and before or after the sheepgrass turns green again, and before other species have turned green and sprouted.

[0031] The precise time window is defined by the difference in phenological periods between Leymus chinensis and its companion species. That is, low-disturbance operations are carried out within the window when Leymus chinensis first enters the early stage of greening, while salt-tolerant companion species such as Imperata cylindrica and Scutellaria barbata have not yet broken dormancy or emerged.

[0032] III. Implement narrow-span, low-disturbance deep tillage and microhabitat construction. Use mechanical implements to carry out narrow-span strip deep tillage operations, with a deep tillage depth of 15-20cm / 25cm and a narrow strip width of 15-30cm. Retain an undisturbed area of ​​50-70cm between adjacent deep tillage strips. Utilize deep tillage to physically cut off aging rhizomes to stimulate the endogenous driving force for axillary bud germination and break up surface compaction to provide conditions for subsequent sexual seed germination.

[0033] IV. In-situ coordinated reseeding of seeds and directional root introduction. Within the narrow strips of deep-plowing, precision sowing, targeted fertilization, and habitat-oriented induction are simultaneously implemented using a mechanical linkage device: In the axial area of ​​the vertical projection of the deep-plowing furrow, Leymus chinensis seeds are precisely sown in a shallow soil layer of 1-2 cm, at a rate of 2-3 kg / mu. The deep-plowing breaks up the surface compaction, creating low-resistance physical channels to construct a "seed bed" conducive to seed germination. Simultaneously, a specialized compound fertilizer, such as urea, is applied 9-13 cm directly below the seeds, constructing a long-lasting nutrient core with a vertical nutrient gradient. Utilizing the nutrient concentration gradient difference between this core and the undisturbed areas on either side, the aging rhizomes on both sides, which have been mechanically truncated and deprived of apical dominance by the deep-plowing, are induced to exhibit a nutrient-seeking response, prompting their lateral buds to transform into "pioneer organs" that migrate and merge towards the central axis of the deep-plowing strip. By controlling the depth of the nutrient core application, the expanding rhizomes are induced to reside horizontally in the deeper soil layer of 10-15 cm within the deep-plowing furrow, thus interacting with the rhizomes distributed in the 1-5 cm layer... The root systems of seedlings replanted in shallow soil layers construct a synchronous heterogeneous distribution structure with spatial dislocation, achieving asexual-sexual synergistic restoration based on complementary spatial resources.

[0034] The mechanism of directional root introduction and heterogeneous succession is as follows: By constructing a long-lasting nutrient core at a depth of 10-15 cm along the vertical projection axis of the deep loosening trench, a directional induction gradient is formed with the undisturbed areas on both sides, activating and inducing the native Leymus chinensis rhizomes to produce a nutrient tropism response; the native Leymus chinensis rhizomes physically merge towards the central axis of the trench within the low mechanical resistance physical channel formed by deep loosening, and construct a non-competitive layered mosaic structure in the vertical space with the seedlings developed from the reseeded seeds; the secondary roots of the reseeded seedlings are planted in the shallow soil layer of 1-5 cm, while the native rhizomes that have migrated and expanded directionally are distributed in the deep soil layer of 10-15 cm. The spatial dislocation of the vertical layer avoids nutrient and spatial competition between asexual and sexual individuals, realizing the directional reshaping and synergistic repair of the community structure.

[0035] V. Field Management. From sowing to the seedling stage of Leymus chinensis, drip irrigation or sprinkler irrigation should be carried out on the sowing area according to the rainfall to ensure the germination of Leymus chinensis seeds and the establishment of seedlings. Grazing should be prohibited in the first year.

[0036] VI. Monitoring of Restoration Effects. During the peak growth period of Leymus chinensis in the year following the implementation of the technology, i.e., when Leymus chinensis enters the heading to flowering stage, quadrat surveys are conducted in the restored areas to comprehensively evaluate the restoration effect. Survey indicators include: monitoring the germination rate and establishment status of reseeded Leymus chinensis using quadrat methods; counting the total number of Leymus chinensis plants in the quadrat to evaluate the effect of asexual and sexual synergistic proliferation; measuring the total vegetation cover in the quadrat to assess its coverage capacity for saline-alkali light spots; and measuring the aboveground biomass of Leymus chinensis and its community in the quadrat. These measures are used to comprehensively evaluate the contribution of this restoration method to the structural reshaping and productivity improvement of degraded saline-alkali grasslands.

[0037] Example 2

[0038] This embodiment further defines Embodiment 1. The following experiment was used to verify the effectiveness of the invention: From April 20th to 25th, 2025, this experiment was conducted in the saline-alkali meadow of Taobei District, Baicheng City, western Jilin Province, using the technology of this invention, namely, the method of simultaneous heterogeneous replanting of Leymus chinensis root and rhizome activation and sexual reseeding in a saline-alkali area. The Leymus chinensis was sparsely distributed in this area, and the soil pH was 8.0-9.5, classifying it as mildly to moderately soda-saltified grassland. On August 23rd, 2025, the species composition, vegetation cover, biomass, and other indicators of the experimental site were investigated. Four months after the implementation of the technology, the synergistic restoration technology, through the dual effects of asexual propagation and sexual colonization, achieved structural reshaping and functional restoration of the degraded saline-alkali grassland, such as... Figure 2-5 It records the landscape of the entire process of technology implementation.

[0039] 1. Significantly improved species diversity and community stability.

[0040] The average number of species per quadrat was 18. 2 The average number of species in the control treatment was 14 species / m². 2 The number of species increased significantly. The total vegetation cover reached 82.4%, far exceeding the 63.3% of the control group. This indicates that narrow-span, low-disturbance deep pine not only activated the native root system but also positively promoted the community's species diversity and overall stability.

[0041] 2. Targeted optimization of dominant species community structure

[0042] Leymus chinensis cover is a key indicator for measuring the success of grassland restoration. The average Leymus chinensis cover in the restored plots jumped to 26.6%, while the control group only reached 5.4%, an increase of nearly four times. This directly demonstrates the powerful ecological effect of synergistic restoration technology in targetedly increasing the proportion of dominant forage grasses. Specifically, the quantity and tillering of native Leymus chinensis were significantly promoted (asexual propagation), while the germination rate of sexually introduced Leymus chinensis seeds reached over 50%, resulting in successful establishment, which were key driving factors for the substantial increase in Leymus chinensis cover.

[0043] 3. Ecosystem productivity has been significantly enhanced:

[0044] The aboveground biomass of the co-remediation plots reached 804.4 g / m³ (fresh and dry weight). 2 and 352.0g / m 2 The two control groups had levels of 457.7 g / m². 2 and 223.1g / m 2The remediation technology increased seeding and dry weight by 75.7% and 57.8%, respectively. This demonstrates that the technology can efficiently translate ecological structure optimization into significant productivity gains, providing an effective solution for degraded saline-alkali grasslands.

Claims

1. A method for remediating saline-alkali land based on simultaneous heterogeneous layering of Leymus chinensis rhizome activation and sexual reseeding, characterized in that, The method includes the following steps: S1. Identify the saline-alkali land areas that need restoration; S2. Determine the time window for carrying out repair work; S3. Implement narrow-span, low-disturbance deep tillage, with the width between adjacent deep tillage strips being greater than the width of the narrow deep tillage strip; S4. Implement in-situ coordinated reseeding and directional root induction. Within the narrow strips where deep loosening has been completed, use a mechanical linkage device to simultaneously implement precision sowing, targeted fertilization, and habitat-oriented induction. Specifically, in the axial area of ​​the vertical projection of the deep loosening furrow, place Leymus chinensis seeds in a shallow soil layer of 1-2 cm at a sowing rate of 2-3 kg / mu. At the same time, place fertilizer at a location 9-13 cm directly below the seeds. The fertilizer application site forms a nutrient core, inducing the expansion of native rhizomes to reside and grow horizontally in the deep soil layer of 10-15 cm within the deep loosening furrow. This creates a spatially displaced, synchronously layered distribution structure with the roots of the reseeded seedlings distributed in the shallow soil layer of 1-5 cm. S5. Field management.

2. The method for remediating saline-alkali land based on simultaneous heterogeneous layering of Leymus chinensis rhizome activation and sexual reseeding as described in claim 1, characterized in that, When identifying saline-alkali land areas requiring restoration, these areas are characterized by native Leymus chinensis populations undergoing natural degradation due to physiological aging, with the following community characteristics: The coverage of sheepgrass is 20-50%, and it is accompanied by salt-tolerant plants.

3. The method for remediating saline-alkali land based on simultaneous heterogeneous layering of Leymus chinensis rhizome activation and sexual reseeding as described in claim 2, characterized in that, The time window for restoration work is within a limited period each year after the soil thaws and before and after the sheepgrass turns green again, before other species have turned green and sprouted.

4. The method for remediating saline-alkali land based on simultaneous heterogeneous layering of Leymus chinensis rhizome activation and sexual reseeding as described in claim 3, characterized in that, When implementing narrow-span, low-disturbance deep tillage, the deep tillage depth is 15-20cm, the width of the narrow deep tillage strip is 15-30cm, and an undisturbed area of ​​50-70cm is reserved between adjacent deep tillage strips.

5. The method for remediating saline-alkali land based on simultaneous heterogeneous layering of Leymus chinensis rhizome activation and sexual reseeding as described in claim 4, characterized in that, Field management specifically involves: from sowing to the seedling stage of Leymus chinensis, drip irrigation or sprinkler irrigation is carried out on the sowing area according to rainfall to ensure the germination of Leymus chinensis seeds and the establishment of seedlings, and to prevent grazing in the first year.

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