A method for assisting populus euphratica seed germination and seedling growth in saline-alkali land

Abstract

The application discloses a method for assisting Populus euphratica seed germination and seedling growth in saline-alkali land, and the method is characterized in that a seedling making base is applied in a high-alkali environment to block the surface layer of saline-alkali, so that the Populus euphratica seed germinates and grows in the base, and a low-to-high saline-alkali gradient is formed from the center to the edge of the seedling making base, so that the early seedling of the Populus euphratica gradually adapts to the saline-alkali environment; when the root system of the seedling is completely developed and the seedling preliminarily has the stress resistance to the saline-alkali, the seedling penetrates the seedling making base to contact the saline-alkali soil in the natural environment, so that the transition of the life process of the Populus euphratica seed developing into a whole body is realized, the adverse effect of a large amount of saline-alkali left on the surface layer after the evaporation of the perennial large amount of river water irrigation on the germination of the Populus euphratica is avoided, and the survival rate of the seedling growth of the Populus euphratica seed is increased.

Description

Technical Field

[0001] The invention relates to the technical field of poplar seed seedling cultivation in a high-alkali environment, and in particular to a method for assisting poplar seeds in germination and seedling development in saline-alkali soil. Background Art

[0002] Traditional methods of raising seedlings in saline-alkali soil primarily rely on methods such as imported soil or "salt washing." These methods are costly, but as soil moisture evaporates, the salt and alkali in the lower layers gradually move to the upper soil layers. Therefore, it is necessary to constantly monitor changes in soil salinity and alkali content, and regularly renew the soil or "wash the salt" to maintain a low salinity and alkali content. In some areas, methods such as laying gravel, spraying chemical film agents, and filling the gaps between saline-alkali soil and imported soil or "salt-washed" soil disrupt the soil pore structure, thereby reducing the upward migration of salt and alkali substances due to soil capillary phenomena. However, this method also reduces the replenishment of water in the upper soil layers.

[0003] Imported soil and "salt washing" are mainly aimed at the phenomenon of soil salinization caused by the evaporation of groundwater and soil moisture from salt and alkali in groundwater. The salt and alkali content in this type of saline-alkali land will increase with the depth of the soil layer. In the habitat of Populus euphratica, the source of salt and alkali is the accumulation of surface salt and alkali substances caused by the residue of salt and alkali after the evaporation of river water. The salt and alkali content of the lower soil is low, so methods such as imported soil or "salt washing" cannot be used. In the early days, the method of large-scale stripping of the surface saline-alkali soil was used to promote the regeneration of Populus euphratica seedlings under the forest. Since most of the habitats of Populus euphratica are desert areas, large-scale stripping of the surface saline-alkali soil caused serious damage to the soil, exacerbating the damage to the desert soil caused by disturbance factors such as wind erosion in the desert area. Summary of the Invention

[0004] The object of the present invention is to provide a method for assisting Populus euphratica seeds to germinate and develop into seedlings in saline-alkali soil, so as to solve the problems raised in the above-mentioned background technology.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for assisting Populus euphratica seeds to germinate and develop into seedlings in saline-alkali soil, comprising the following steps:

[0006] S1. Prepare a seedling base plate using a mold with an outer diameter of 10 cm, a depth of 25 cm, an inner diameter of 4 cm, and a depth of 10 cm;

[0007] S2. Before the Populus euphratica capsules crack and according to the planting requirements in the forest, the prepared seedling base tray is buried in the forest, wherein the spacing between trees and rows in the forest is 2m×2m, the pre-buried distance of the seedling base tray is consistent with the spacing between trees and rows in the forest, and the edge of the seedling base tray is 3-5cm higher than the forest, so that river water can enter the seedling base tray through lateral transportation, and the outer wall of the seedling base tray and the matrix are used to filter and intercept some saline-alkali substances;

[0008] S3. Fill the seedling tray with clean soil, 1 cm below the top of the tray to prevent the seeds from floating away with the water after sowing. Spray enough water until the soil inside and outside the tray is fully moistened.

[0009] S4. Observe the development of the Populus euphratica seedlings in the seedling tray, perform appropriate thinning and seedling replacement according to the germination and growth of the seeds in the seedling tray, and reasonably control the seedling density;

[0010] S5. Irrigate the afforestation land after the seeds germinate. Irrigate once a day after the seeds germinate with shallow water flow to ensure the water required by the seedlings during growth;

[0011] S6. After the seedlings grow to 30 cm, apply top dressing to the seedlings in the seedling tray to promote leaf growth and prepare a nutritional basis for lignification in the later growth stage of the seedlings.

[0012] Preferably, in S5, no thinning is required from the time the seeds germinate to the time they grow to 2 leaves;

[0013] When the seeds germinate and grow to 4 leaves, the seedling base with low seedling density should be supplemented with seeds or poplar catkins should be spread;

[0014] When the seedlings grow to 8 leaves, thin them out and control the number of 8-leaf seedlings in the seedling tray to 10-15;

[0015] When the seedlings grow to a height greater than 20 cm, thin out the seedlings in the seedling tray to 3-5 plants in each seedling tray.

[0016] Preferably, in S6, topdressing the seedlings in the seedling base tray is performed by pouring 100 g / L urea solution into the seedling base tray and its surroundings or fertilizing and irrigating according to 50 kg / mu of urea.

[0017] Preferably, the preparation of the seedling base plate in S1 comprises the following steps:

[0018] S11. Dry peat soil, perlite, vermiculite, sphagnum moss, and sheep dung soil are mixed thoroughly in a volume ratio of 8:2:1:8:1, and then soaked in water until all the materials have absorbed enough water to prepare a matrix soil for later use.

[0019] S12. Select viscous riverbed mud from local rivers, dry it in the oven or sun, and then crush it into powder for use as a natural binder;

[0020] S13, evenly mixing S11 and S12 until the matrix soil is squeezed into shape, and filling the matrix soil into the seedling base tray mold, continuously compacting the filler while filling, and then pressing into shape using the mold;

[0021] S14, placing the seedling base plate formed by pressing in S13 in a cool and ventilated place to dry in the shade for 3 days to prevent the seedling base plate from losing moisture too quickly, causing cracking and changing the compactness;

[0022] S15, baking the seedling base plate in S14 to kill insect eggs and microorganisms;

[0023] S16. Use a spray bottle to evenly spray or apply 4% diluted polyurethane on the outside of the seedling base tray in 2-3 layers. After spraying or applying one layer, wait until it forms a milky white or light yellow film, then spray or apply another layer. Then, let the seedling base tray sprayed or applied with polyurethane dry completely.

[0024] Preferably, the matrix soil forming standard in S13 is that it basically maintains its original shape after a 30 cm free fall and basically maintains its original shape when immersed in water.

[0025] Preferably, the seedling base plate in S15 is baked in a 105°C oven for 24 hours.

[0026] Preferably, the main components of the polyurethane in S16 are: polyurethane, content 74%; toluene diisocyanate, content 11%; butanone, content 15%.

[0027] Compared with the prior art, the beneficial effects of the present invention are: by applying the seedling base in a high-alkali environment to block the surface salt and alkali, the poplar seeds germinate and grow therein, and a salt and alkali gradient is formed from low to high from the center to the edge of the seedling base, so that the early poplar seedlings gradually adapt to the saline-alkali environment. When the seedling root system is fully developed and initially has resistance to salt and alkali, it penetrates the seedling base and contacts the saline-alkali soil in the natural environment, thereby realizing the transition of the life process of the poplar seeds into complete individuals, avoiding the adverse effects of the large amount of salt and alkali left on the surface after the evaporation of a large amount of river water throughout the year on the germination of the poplar, and increasing the survival rate of the poplar seedlings. DETAILED DESCRIPTION

[0028] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0029] The present invention uses the long-term fixed monitoring sample site of Erdaoqiao in Ejina Banner, Alxa League, Inner Mongolia Autonomous Region, a saline-alkali land in an inland high-temperature area, as the afforestation land of the present invention.

[0030] Populus euphratica is drought-tolerant and salt-alkali-tolerant. Much of its habitat is saline-alkali soil. Year-round, high levels of river water flooding poplar forests cause water evaporation, leading to a significant accumulation of salt and alkali on the surface, forming a thin salt crust. Populus euphratica seeds cannot survive in high-salinity environments during germination. However, one-year-old seedlings exhibit a certain degree of tolerance to high salinity and alkali stress, and this tolerance gradually increases with age.

[0031] Populus euphratica seeds mainly rely on moist soil to capture seeds carried in flying catkins for spread. The falling position is just on the soil surface. The topsoil contains a large amount of saline-alkali precipitates (salt crust). After germination, the Populus euphratica seeds cannot adapt to the high saline-alkali stress and cannot complete the subsequent development process.

[0032] It has been observed in nature that during the poplar catkin season, river water seeps down near the river channel and washes the surface salt and alkali into the deep soil layer. Sampling and testing of the surface soil (0-10 cm) before and after flooding with river water found that the conductivity of the surface soil would decrease from 5.22±1.29 mS / cm to 1.73±0.79 mS / cm, and the pH of the surface soil would decrease from 9.53±0.67 to 8.39±0.32. After the moisture in the surface soil completely evaporated, the surface soil (0-10 cm) was taken for testing, and the conductivity returned to 5.39±1.63 mS / cm, and the pH returned to 9.59±0.74. The salinity and alkali content in the deep soil of the Populus euphratica population gradually decreased with increasing soil thickness. The soil conductivity at 10-20 cm was 2.11 ± 0.49 mS / cm, 20-40 cm was 0.87 ± 0.19 mS / cm, 40-60 cm was 0.47 ± 0.13 mS / cm, and 60-100 cm was 0.22 ± 0.09 mS / cm. This suggests that the source of salinity and alkali is primarily the accumulation of salinity and alkali in river water, rather than groundwater. Therefore, blocking the surface salinity and alkali environment is of great significance to the development of Populus euphratica seedlings. Once the root system of the Populus euphratica seedlings grows to a length greater than 10 cm, the salinity and alkali content drops below the tolerance threshold of the Populus euphratica seedlings' roots.

[0033] In nature, poplars reproduce asexually through root shoots, which results in a uniform genotype and an imbalanced male-female ratio in the forest, making it difficult to naturally select individuals with greater resilience. Unstable river water levels in poplar habitats prevent seeds from developing into seedlings after landing during the breeding season.

[0034] Therefore, we use degradable artificial seedling bases to help isolate the surface saline-alkali soil from the poplar seeds. When the seedlings' roots are fully developed and initially have resistance to salt and alkali, they can penetrate the seedling base through natural growth and come into contact with the saline-alkali soil in the natural environment, thus completing the life process of the poplar seeds developing into complete individuals and providing assistance for the subsequent natural screening of high-quality stress-resistant genes.

[0035] Preparation of seedling making base plate, comprising the following steps:

[0036] The dry grass charcoal soil, perlite, vermiculite, water moss and sheep manure are respectively mixed according to the volume ratio of 8:2:1:8:1, then fully mixed and soaked with water until all the materials absorb water, so as to prepare the substrate soil for standby use;

[0037] The sticky riverbed sediment is selected from a local river channel, dried or sun-dried, and then crushed into powder as a natural binder for standby use;

[0038] The substrate soil and the natural binder are uniformly mixed until the substrate soil can be formed by extrusion, the forming condition of the substrate soil is adjusted by adding the riverbed sediment powder, the forming standard of the substrate soil needs to keep the original shape after a 30cm free fall and keep the original shape after soaking in water, then the substrate soil is filled into a seedling making base plate mold, the filler is continuously compacted while filling, and then the mold is pressed to form, the mold has an outer diameter of 10cm, a depth of 25cm, an inner diameter of 4cm and a depth of 10cm;

[0039] The seedling making base plate formed by the mold pressing is placed in a cool and ventilated place for 3 days of shade drying, so as to prevent the seedling making base plate from cracking and changing the compactness due to too fast water loss;

[0040] The seedling making base plate after shade drying is placed in a 105°C oven for continuous baking for 24 hours, so as to kill insect eggs and microorganisms;

[0041] The polyurethane (HYCEL OH-1A) diluted by 4% is uniformly sprayed or applied on the outside of the seedling making base plate for 2-3 layers, after spraying a layer, the second spraying or application is performed after a milky white or light yellow film is formed, and then the seedling making base plate is completely dried.

[0042] The polyurethane (HYCEL OH-1A) used in the application is purchased from the product produced by Japan Meibang Chemical Industry Co., Ltd., and the main components of the polyurethane (HYCEL OH-1A) are: polyurethane (prepolymer), content 74%; toluene diisocyanate (TDI), content 11%; butanone, content 15%.

[0043] A method for assisting Populus euphratica seed germination and seedling growth in saline-alkali land, comprising the following steps:

[0044] Seeding and early seedling cultivation:

[0045] Before the Populus euphratica capsules crack and according to the planting requirements in the forest, the prepared seedling base is buried in the forest, wherein the spacing between trees and rows in the forest is 2m×2m, the pre-buried distance of the seedling base is consistent with the spacing between trees and rows in the forest, and the edge of the seedling base is 3-5cm higher than the forest, so that river water can be transported horizontally into the seedling base, and the outer wall of the seedling base and the matrix are used to filter and intercept some saline-alkali substances;

[0046] Fill the seedling tray with clean soil, the soil height should be 1cm lower than the top of the seedling tray to prevent the seeds from floating away with the water after sowing. Spray enough water until the soil inside and outside the seedling tray is fully moistened.

[0047] Observe the development of Populus euphratica seedlings in the seedling tray, and carry out appropriate thinning and seedling replacement according to the germination and growth of seeds in the seedling tray. Reasonably control the seedling density. No thinning is required from the time the seeds germinate to the time they grow to 2 leaves.

[0048] When the seeds germinate and grow to 4 leaves, the seedling base with low seedling density should be supplemented with seeds or poplar catkins should be spread;

[0049] When the seedlings grow to 8 leaves, thin them out and control the number of 8-leaf seedlings in the seedling tray to 10-15;

[0050] When the seedlings grow to a height greater than 20 cm, thin out the seedlings in the seedling tray to 3-5 plants per tray;

[0051] Irrigate the afforestation land after the seeds germinate. Irrigate once a day after the seeds germinate. It is best to irrigate with a trickle and shallow irrigation in the early morning or evening to avoid large-scale water loss during high temperature periods. Or use drip irrigation for 4 hours after the sun rises and before the sun sets to ensure the water needed during the growth period.

[0052] Management of late seedlings:

[0053] After the seedlings grow to 30 cm, they need to be top-dressed to promote leaf growth and prepare a nutritional basis for lignification in the later growth period of the seedlings. Top-dressing can be done by pouring 100 g / L urea solution into the seedling tray and its surroundings or by fertilizing and irrigating with 50 kg / mu of urea.

[0054] The method comprises mixing peat soil, perlite, vermiculite, sphagnum moss, sheep dung soil and local riverbed mud in proportion, pressing the soil into a specific shape using a die tool, and then drying it in the sun, and spraying low-concentration polyurethane (HYCEL) on the outside. OH-1A) maintains its shape and allows water to pass freely while blocking the lateral movement of salt and alkali with water. The vermiculite and perlite in the seedling base have the characteristics of physical water absorption, which can maintain the moisture of the soil around the seedling base to a certain extent. The sphagnum moss activates biological activity after meeting water, and absorbs saline and alkali substances to a certain extent while retaining water. Since the materials used in the seedling base itself are all natural materials, they can be naturally degraded into soil nutrients to supply other poplar seedlings and other plants for growth and development. The structure of the seedling base is similar to the soil structure in the suitable habitat of poplar. It is loose and breathable, ensuring the free growth and penetration of plant roots. Since the seedling base itself cannot completely block saline and alkali substances, a small amount of saline and alkali remains in the seedling base with the transfer of water. A saline and alkali gradient is formed from low to high from the center to the edge of the seedling base, allowing the early poplar seedlings to gradually adapt to the saline and alkali environment.

[0055] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for assisting Populus euphratica seeds to germinate and grow into seedlings in saline-alkali soil, characterized in that: The following steps are involved: S1. Prepare a seedling base plate using a mold with an outer diameter of 10 cm, a depth of 25 cm, an inner diameter of 4 cm, and a depth of 10 cm; S2. Before the Populus euphratica capsules crack and according to the planting requirements in the forest, bury the seedling base tray prepared in S1 in the forest, wherein the spacing between trees and rows in the forest is 2m×2m, the pre-buried distance of the seedling base tray is consistent with the spacing between trees and rows in the forest, and the edge of the seedling base tray is 3-5cm higher than the forest, so that river water can be transported horizontally into the seedling base tray, and the outer wall of the seedling base tray and the matrix are used to filter and intercept some saline-alkali substances; S3. Fill the seedling tray with clean soil, 1 cm below the top of the tray to prevent the seeds from floating away with the water after sowing. Spray enough water until the soil inside and outside the tray is fully moistened. S4. Observe the development of the Populus euphratica seedlings in the seedling tray, perform appropriate thinning and seedling replacement according to the germination and growth of the seeds in the seedling tray, and reasonably control the seedling density; S5. Irrigate the afforestation land after the seeds germinate. Irrigate once a day after the seeds germinate with shallow water flow to ensure the water required by the seedlings during growth; S6. After the seedlings grow to 30 cm, topdress the seedlings in the seedling tray to promote leaf growth and prepare a nutritional basis for lignification in the later growth stage of the seedlings; The preparation of the seedling base plate in S1 includes the following steps: S11. Dry peat soil, perlite, vermiculite, sphagnum moss, and sheep dung soil are mixed thoroughly in a volume ratio of 8:2:1:8:1, and then soaked in water until all the materials have absorbed enough water to prepare a matrix soil for later use. S12. Select viscous riverbed mud from local rivers, dry it in the oven or sun, and then crush it into powder for use as a natural binder; S13, evenly mixing S11 and S12 until the matrix soil is squeezed into shape, and filling the matrix soil into the seedling base tray mold, continuously compacting the filler while filling, and then pressing into shape using the mold; S14, placing the seedling base plate formed by pressing in S13 in a cool and ventilated place to dry in the shade for 3 days to prevent the seedling base plate from losing moisture too quickly, causing cracking and changing the compactness; S15, baking the seedling base plate in S14 to kill insect eggs and microorganisms, and baking the seedling base plate in a 105°C oven for 24 hours; S16. Use a spray can to evenly spray or apply 2-3 layers of polyurethane diluted 4% on the outside of the seedling base plate. After spraying or applying one layer, wait for it to form a milky white or light yellow film, then spray or apply another layer. Then, completely dry the seedling base plate after spraying or applying polyurethane. By applying the seedling base in a high-alkaline environment to block the surface salt and alkali, the Populus euphratica seeds can germinate and grow inside it, and a salt-alkali gradient from low to high is formed from the center to the edge of the seedling base, so that the early Populus euphratica seedlings can gradually adapt to the saline-alkali environment.

2. The seedling raising method according to claim 1, wherein In S5, thinning was not required from seed germination to the growth of 2 leaves; When the seeds germinate and grow to 4 leaves, the seedling base with low seedling density should be supplemented with seeds or poplar catkins should be spread; When the seedlings grow to 8 leaves, thin them out and control the number of 8-leaf seedlings in the seedling tray to 10-15; When the seedlings grow to a height greater than 20 cm, thin out the seedlings in the seedling tray to 3-5 plants in each seedling tray.

3. The seedling raising method according to claim 1 or 2, wherein: In S6, topdressing of the seedlings in the seedling tray is carried out by pouring 100 g / L urea solution into the seedling tray and its surroundings or fertilizing and irrigating at 50 kg / mu of urea.

4. The seedling raising method according to claim 1, wherein: The standard for the matrix soil formation in S13 is that it basically maintains its original shape after a 30cm free fall and basically maintains its original shape when immersed in water.

5. The seedling raising method according to claim 1, wherein: The main components of polyurethane in S16 are: polyurethane, content 74%; toluene diisocyanate, content 11%; butanone, content 15%.