A method for cultivating and field planting of endangered semi-mangrove plant Aegiceras corniculatum seedlings

Abstract

The application discloses a kind of endangered semi-mangrove plant seafront cat tail wood seedling cultivation and field planting method, and relates to the technical field of plant cultivation.The seedling cultivation method mainly includes seed collection, seed pretreatment, seed germination, seedling raising, hardening-off and planting, and the field planting method mainly includes seedling selection, planting area selection, habitat reconstruction and seedling field planting.The method of the present application overcomes the shortcomings of the prior art, provides the best conditions for the adaptation of the natural environment of the seafront cat tail wood, significantly improves the survival rate of the seedlings, which is as high as 90%, and also provides a population recovery method for the endangered mangrove plant seafront cat tail wood.The method has low cost and good effect.

Description

Technical Field

[0001] This invention relates to the field of plant cultivation technology, and in particular to a method for cultivating seedlings and planting them in the wild of the endangered semi-mangrove plant, *Cercis chinensis*. Background Technology

[0002] *Dolichandrone spathacea*, commonly known as the seaside cat's tail tree, is an evergreen tree belonging to the genus *Dolichandrone* in the family Bignoniaceae. It is a semi-mangrove plant, reaching a height of 5-20 meters. The bark is gray to dark brown, and the twigs are stout. The leaves are opposite, odd-pinnate compound leaves with 2-4 pairs of leaflets, which are ovate to ovate-lanceolate, 5-16 cm long and 3-7 cm wide. The racemes have 2-8 flowers with stout pedicels. The calyx is green, tubular, 4-8 cm long, and splits nearly to the base on one side near the axis at flowering time, forming a spathe-like structure with a blunt apex bearing a short, reflexed point covered with purple glands. The corolla is initially green, turning white when open, trumpet-shaped, with glands on the upper outer part of the tube. The capsule is tubular and slightly flattened, drooping, usually slightly curved, 25-50 cm long and about 1.8 cm wide, splitting into two valves when mature. The seeds are numerous, with corky wings, and oblong. It grows in mudflats accessible by high tides, but can also grow on land completely unaffected by tides. *Cynodon dactylon* is naturally distributed in southern India, Sri Lanka, and New Caledonia (island), and also on the east coast of Hainan Island and Zhanjiang City, Guangdong Province, China. Habitat destruction is its main cause of endangerment, and in 2006, *Cynodon dactylon* was listed in the "List of Key Protected Wild Plants of Hainan Province". *Cynodon dactylon* is a good species for coastal protection forests, as well as an ornamental and street tree for cities, possessing significant ecological and economic value and broad prospects for development and utilization. The "Special Action Plan for the Protection and Restoration of Mangroves (2020-2025)" issued by the Ministry of Natural Resources and the National Forestry and Grassland Administration in 2020 clearly stipulates the protection of rare and endangered mangrove species and the expansion of the area inhabited by rare and endangered mangrove species.

[0003] Our research team previously solved the seedling cultivation technology of *Cercis chinensis*, and through technical exploration, introduced the cultivated seedlings into the wild, significantly improving their survival rate. We have now mastered a mature set of planting and nurturing techniques, which have important guiding significance for the conservation of endangered mangrove plants in my country. Summary of the Invention

[0004] To address the aforementioned deficiencies in the existing technology, this invention proposes a method for seedling cultivation and field planting of the endangered semi-mangrove plant, *Cercidiphyllum heliotropium*, in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0007] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0008] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 3-10 hours, then wrap them in gauze soaked in 0.1-0.6% emodin methyl ether and place them in an incubator for variable temperature culture for 8-12 days to obtain pretreated seeds; the pretreatment solution, by weight, includes 30-50 parts rice husk liquid, 10-16 parts 1-hydroxy-2-piperidinecarboxylic acid, 5-10 parts azelaic acid and 500-700 parts water;

[0009] (3) Seed germination: Spread the pretreated seeds obtained in step (2) evenly on the seedbed, and spray 15-25 ml of 6-benzyladenine solution with a mass concentration of 20-45 mg / L per square meter of seedbed every day, 2-3 times a day, for 10-20 days to obtain germinating seeds.

[0010] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 2-5 cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 20-30 parts peat, 10-15 parts Chlorella vulgaris and 1-5 parts fulvic acid. The promoter, by weight, includes 5-16 parts paclitaxel, 3-7 parts D-carvone, 1-5 parts dodecyl aldehyde, 1-3 parts geraniol and 1-3 parts water.

[0011] (5) Hardening off seedlings: After the seedlings have grown to more than 4cm in height, transfer them to hardening off bags and set up hardening off substrate in the bags. After placing the seedlings, cover them with a thin layer of sand, spray hardening off agent, and then harden off seedlings.

[0012] (6) Planting: After the seedlings have grown to 30-40cm in height after hardening treatment, they can be planted in the wild.

[0013] Preferably, the preparation method of the pretreatment liquid in step (2) is as follows: 1-hydroxy-2-piperidinic acid, azelaic acid and water are mixed and heated to 35-40°C while stirring to obtain a mixed liquid; the mixed liquid is placed in a ventilated place, and rice husk liquid is added after the temperature of the mixed liquid drops to 22-25°C to obtain the pretreatment liquid.

[0014] Preferably, the method for preparing the rice husk liquid in step (2) is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g:(10-15) mL, stir and heat to 70-80°C, let stand for 30-60 min, and filter to obtain the rice husk liquid.

[0015] Preferably, the incubator in step (2) is set up with the following conditions: first, medium temperature incubation at 30-40℃ for 4-7 hours, then low temperature incubation at 15-20℃ for 1-3 hours, and finally high temperature incubation at 42-50℃ for 8-12 hours, and so on until the variable temperature incubation ends.

[0016] Preferably, the salinity of the water in step (4) is 8-12‰.

[0017] Preferably, the seedling substrate in step (5) comprises, by weight, 15-20 parts biochar, 10-12 parts tea residue, 10-12 parts rice husk, 7-12 parts sumac (root, leaf, flower, and fruit of sumac Mill., a plant of Anacardiaceae family), 5-10 parts salvia europaea L. (an annual herb of the genus Salvia in the Amaranthaceae family), 5-10 parts calcium magnesium phosphate fertilizer, 1-3 parts potassium sulfate, and 30-45 parts seawater.

[0018] Preferably, a method for planting the endangered semi-mangrove plant *Cercidiphyllum heliotropium* in the wild includes the following steps:

[0019] S1. Seedling selection: Select seaside cat's tail tree seedlings cultivated according to the seedling cultivation method of any one of claims 1 to 6;

[0020] S2. Planting area selection: Select the area within 0 to 10 meters of the outer edge of the supratidal zone where true mangroves are distributed, preferably abandoned aquaculture ponds with semi-mangroves distributed around them;

[0021] S3. Habitat modification: Remove debris from the planting area, level the land to an elevation of 1.0 to 3.0 meters, and dig longitudinal tidal ditches every 5.0 meters, with a width of 1.0 meter at the top and 0.5 meters at the bottom, and a depth of 1.0 meter;

[0022] S4. Seedling planting in the wild: Select the planting month, set the planting spacing to 2m*2m, the diameter of the planting hole to be 15-20cm, and the depth to be 20-30cm; when planting, use a tool to cut off the bottom of the seedling bag, put the remaining seedling bag and seedling into the planting hole, compact the soil of the planting hole, and water it thoroughly with fresh water to complete the planting in the wild.

[0023] Preferably, the seaside cattail seedlings selected in step S1 are three-year-old seedlings.

[0024] Preferably, the elevation in step S3 is 2.0 meters.

[0025] Preferably, the planting month in step S4 is March.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] (1) Pre-treatment of seeds by soaking in pre-treatment solution + emodin methyl ether + variable temperature culture can not only provide the water required for seed germination and ensure seed germination, but also shorten the seed germination time. Rice husk liquid contains a variety of nutrients, such as nitrogen, phosphorus and potassium, which can participate in protein synthesis and chlorophyll formation, providing the nutrients required for seed germination. Variable temperature culture can effectively and quickly break the dormancy of seashore cattail seeds through temperature cycling, while improving the seed germination rate and increasing the efficiency and economic benefits of batch cultivation.

[0028] (2) The growth fertilizer and accelerator used in seedling cultivation effectively ensure the nutrients required for seedling growth, and most of the components are plant-derived effective ingredients. Plant-derived organic fertilizer contains abundant macromolecules such as cellulose, hemicellulose, lignin, and protein, which enhances the soil's ability to retain and supply nutrients and its buffering capacity within the seedling bags, creating favorable soil conditions for crop growth while reducing the use of chemical fertilizers. The salinity of the water in the accelerator is 8-12‰. A suitable salinity setting can maintain good seedling growth while providing a simulated environment for subsequent field planting of *Ceratophyllum demersum*.

[0029] (3) The sumac powder and salsa powder in the seedling hardening substrate are both made from salt-tolerant plants. They contain special substances that help the plants adapt to the salt-alkali environment, which can help the seaside cattail seedlings better adapt to the high salt environment when planted in the wild and improve the seedlings' salt tolerance.

[0030] (4) The method of the present invention overcomes the shortcomings of the prior art and provides the best conditions for the growth characteristics of seashore cattail wood to adapt to the natural environment, significantly improving the survival rate of seedlings, which is as high as 90%. It also provides a method for the population restoration of the endangered mangrove plant seashore cattail wood. This method is low in cost and effective. Attached Figure Description

[0031] Figure 1 A schematic diagram of the wild planting area for seashore cat's tail seedlings (supratidal zone);

[0032] Figure 2 This is a schematic diagram of seaside cat's tail tree planting; where A represents two-year-old seedlings; B represents the planting spacing; and C represents plants that have reached stable growth after six months.

[0033] Figure 3 This is a diagram showing the plant one year after planting.

[0034] Figure 4 This is a diagram showing the plant two years after planting; A represents the mature fruit; B represents the plant that produced the fruit. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below with reference to specific embodiments.

[0036] Example 1

[0037] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0038] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0039] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 3 hours, then wrap them in gauze soaked in 0.1% emodin methyl ether and place them in an incubator for variable temperature culture for 8 days to obtain pretreated seeds.

[0040] The pretreatment solution is prepared by mixing 10 parts of 1-hydroxy-2-piperidinecarboxylic acid, 5 parts of azelaic acid and 500 parts of water, stirring and heating to 35°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 22°C, 30 parts of rice husk liquid are added to obtain the pretreatment solution.

[0041] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 10 mL, while stirring, heat to 70°C, let stand for 30 min, and filter to obtain the rice husk liquid.

[0042] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 30℃ for 4 hours, then at a low temperature of 15℃ for 1 hour, and then at a high temperature of 42℃ for 8 hours, and this cycle is repeated until the variable temperature incubation ends.

[0043] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 15 ml of 6-benzyladenine solution with a mass concentration of 20 mg / L per square meter of seedbed every day, spray twice a day for 10 days to obtain germinating seeds.

[0044] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay a 2cm high layer of growth fertilizer and promoter in the seedling bag from bottom to top. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 20 parts peat, 10 parts Chlorella vulgaris and 1 part fulvic acid. The promoter, by weight, includes 5 parts paclitaxel, 3 parts D-carvone, 1 part dodecyl aldehyde, 1 part geraniol and 1 part water with a salinity of 8‰.

[0045] (5) Hardening off seedlings: After the seedlings have grown to more than 4cm in height, transfer them to hardening off bags and set up hardening off substrate in the bags. After placing the seedlings, cover them with a thin layer of sand, spray hardening off agent, and then harden off seedlings.

[0046] The seedling hardening substrate comprises, by weight, 15 parts biochar, 10 parts tea residue, 10 parts rice husk, 7 parts sumac powder, 5 parts saltwort powder, 5 parts calcium magnesium phosphate fertilizer, 1 part potassium sulfate and 30 parts seawater.

[0047] (6) Planting: Once the seedlings have grown to 30cm in height after hardening treatment, they can be planted in the wild.

[0048] Example 2

[0049] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0050] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0051] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 10 hours, then wrap them in gauze soaked in 0.6% emodin methyl ether and place them in an incubator for variable temperature culture for 12 days to obtain pretreated seeds.

[0052] The pretreatment solution is prepared by mixing 16 parts of 1-hydroxy-2-piperidinecarboxylic acid, 10 parts of azelaic acid and 700 parts of water, stirring and heating to 40°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 25°C, 50 parts of rice husk liquid are added to obtain the pretreatment solution.

[0053] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 15 mL, stir and heat to 80°C, let stand for 60 min, and filter to obtain the rice husk liquid.

[0054] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 40℃ for 7 hours, then at a low temperature of 20℃ for 3 hours, and then at a high temperature of 50℃ for 12 hours, and this cycle is repeated until the temperature variation incubation ends.

[0055] (3) Seed germination: Spread the pretreated seeds obtained in step (2) evenly on the seedbed, spray 25 ml of 6-benzyladenine solution with a mass concentration of 45 mg / L per square meter of seedbed every day, spray 3 times a day for 20 days to obtain germinating seeds;

[0056] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay a 5cm high layer of growth fertilizer and promoter in the seedling bag from bottom to top. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 30 parts peat, 15 parts Chlorella proteoglycans and 5 parts fulvic acid. The promoter, by weight, includes 16 parts paclitaxel, 7 parts D-carvone, 5 parts dodecyl aldehyde, 3 parts geraniol and 3 parts water with a salinity of 12‰.

[0057] (5) Hardening off seedlings: After the seedlings have grown to more than 4cm in height, transfer them to hardening off bags and set up hardening off substrate in the bags. After placing the seedlings, cover them with a thin layer of sand, spray hardening off agent, and then harden off seedlings.

[0058] The seedling hardening substrate comprises, by weight, 20 parts biochar, 12 parts tea residue, 12 parts rice husk, 12 parts sumac powder, 10 parts saltwort powder, 10 parts calcium magnesium phosphate fertilizer, 3 parts potassium sulfate and 45 parts seawater.

[0059] (6) Planting: Once the seedlings have grown to 40cm in height after hardening treatment, they can be planted in the wild.

[0060] Example 3

[0061] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0062] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0063] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds.

[0064] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0065] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0066] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 35℃ for 5 hours, then at a low temperature of 18℃ for 2 hours, and then at a high temperature of 45℃ for 10 hours, and this cycle is repeated until the variable temperature incubation ends.

[0067] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0068] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 3cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella proteoglycans and 2 parts fulvic acid. The promoter, by weight, includes 10 parts paclitaxel, 5 parts D-carvone, 3 parts dodecyl aldehyde, 2 parts geraniol and 2 parts water with a salinity of 10‰.

[0069] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0070] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0071] Comparative Example 1

[0072] The difference between this comparative example and Example 3 is that the pretreatment liquid in step (2) is replaced with 42°C warm water, while the other components and steps remain unchanged.

[0073] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0074] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0075] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in 42℃ warm water for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds;

[0076] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 35℃ for 5 hours, then at a low temperature of 18℃ for 2 hours, and then at a high temperature of 45℃ for 10 hours, and this cycle is repeated until the variable temperature incubation ends.

[0077] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0078] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 3cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella proteoglycans and 2 parts fulvic acid. The promoter, by weight, includes 10 parts paclitaxel, 5 parts D-carvone, 3 parts dodecyl aldehyde, 2 parts geraniol and 2 parts water with a salinity of 10‰.

[0079] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0080] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0081] Comparative Example 2

[0082] The difference between this comparative example and Example 3 is that the emodin methyl ether in step (2) is replaced with a gibberellin solution with a mass concentration of 0.1 g / L, while the other components and steps remain unchanged.

[0083] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0084] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0085] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in gibberellin solution with a mass concentration of 0.1 g / L, and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds;

[0086] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0087] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0088] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 35℃ for 5 hours, then at a low temperature of 18℃ for 2 hours, and then at a high temperature of 45℃ for 10 hours, and this cycle is repeated until the variable temperature incubation ends.

[0089] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0090] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 3cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella proteoglycans and 2 parts fulvic acid. The promoter, by weight, includes 10 parts paclitaxel, 5 parts D-carvone, 3 parts dodecyl aldehyde, 2 parts geraniol and 2 parts water with a salinity of 10‰.

[0091] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0092] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0093] Comparative Example 3

[0094] The difference between this comparative example and Example 3 is that the variable temperature culture in step (2) is replaced with a constant temperature of 15°C, while the other components and steps remain unchanged.

[0095] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0096] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0097] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator at a constant temperature of 15℃ for 10 days to obtain pretreated seeds.

[0098] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0099] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0100] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0101] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 3cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella proteoglycans and 2 parts fulvic acid. The promoter, by weight, includes 10 parts paclitaxel, 5 parts D-carvone, 3 parts dodecyl aldehyde, 2 parts geraniol and 2 parts water with a salinity of 10‰.

[0102] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0103] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0104] Comparative Example 4

[0105] The difference between this comparative example and Example 3 is that the temperature order of the variable temperature culture in step (2) is changed, while the other components and steps remain the same.

[0106] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0107] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0108] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds.

[0109] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0110] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0111] The incubator is set up with the following conditions: first, it is incubated at a low temperature of 18℃ for 2 hours, then at a high temperature of 45℃ for 10 hours, and then at a medium temperature of 35℃ for 5 hours, and this cycle is repeated until the variable temperature incubation ends.

[0112] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0113] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 3cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella proteoglycans and 2 parts fulvic acid. The promoter, by weight, includes 10 parts paclitaxel, 5 parts D-carvone, 3 parts dodecyl aldehyde, 2 parts geraniol and 2 parts water with a salinity of 10‰.

[0114] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0115] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0116] Comparative Example 5

[0117] The difference between this comparative example and Example 3 is that there is no growth fertilizer in step (4), while the other components and steps remain unchanged.

[0118] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0119] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0120] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds.

[0121] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0122] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0123] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 35℃ for 5 hours, then at a low temperature of 18℃ for 2 hours, and then at a high temperature of 45℃ for 10 hours, and this cycle is repeated until the variable temperature incubation ends.

[0124] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0125] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay a 3cm high layer of accelerator in the seedling bag. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The accelerator, by weight, includes 10 parts of leucine, 5 parts of D-carvone, 3 parts of dodecyl aldehyde, 2 parts of geraniol and 2 parts of water with a salinity of 10‰.

[0126] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0127] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0128] Comparative Example 6

[0129] The difference between this comparative example and Example 3 is that there is no accelerator in step (4), while the other components and steps remain unchanged.

[0130] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0131] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0132] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds.

[0133] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0134] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0135] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 35℃ for 5 hours, then at a low temperature of 18℃ for 2 hours, and then at a high temperature of 45℃ for 10 hours, and this cycle is repeated until the variable temperature incubation ends.

[0136] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0137] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay a 3cm high layer of growth fertilizer in the seedling bag. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten them, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella vulgaris and 2 parts humic acid.

[0138] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0139] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0140] Comparative Example 7

[0141] The difference between this comparative example and Example 3 is that the water in step (4) is fresh water, while the other components and steps remain unchanged.

[0142] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0143] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0144] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds.

[0145] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0146] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0147] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 35℃ for 5 hours, then at a low temperature of 18℃ for 2 hours, and then at a high temperature of 45℃ for 10 hours, and this cycle is repeated until the variable temperature incubation ends.

[0148] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0149] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay a 3cm high layer of growth fertilizer and promoter in the seedling bag from bottom to top. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella vulgaris and 2 parts humic acid. The promoter, by weight, includes 10 parts paclitaxel, 5 parts D-carvone, 3 parts dodecyl aldehyde, 2 parts geraniol and 2 parts water.

[0150] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. The hardening off substrate is sprayed with hardening off agent and then hardened off. The hardening off substrate consists of 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 10 parts sumac powder, 8 parts saltwort powder, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0151] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0152] Comparative Example 8

[0153] The difference between this comparative example and Example 3 is that the seedling substrate in step (4) does not contain sumac powder and salvia powder, while the other components and steps remain unchanged.

[0154] A method for cultivating seedlings of the endangered semi-mangrove plant *Cercidiphyllum heptaphyllum* includes the following steps:

[0155] (1) Seed collection: Collect the split fruits from the upper half of the seaside cat's tail tree in August and September and keep them for later use.

[0156] (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 8 hours, then wrap them in gauze soaked in 0.5% emodin methyl ether and place them in an incubator for variable temperature culture for 10 days to obtain pretreated seeds.

[0157] The pretreatment solution is prepared by mixing 15 parts of 1-hydroxy-2-piperidinecarboxylic acid, 7 parts of azelaic acid and 600 parts of water, stirring and heating to 38°C to obtain a mixed solution; the mixed solution is placed in a ventilated place, and after the temperature of the mixed solution drops to 24°C, 40 parts of rice husk liquid are added to obtain the pretreatment solution.

[0158] The method for preparing the rice husk liquid is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: 12 mL, while stirring, heat to 75°C, let stand for 50 min, and filter to obtain the rice husk liquid.

[0159] The incubator is set up with the following conditions: first, it is incubated at a medium temperature of 35℃ for 5 hours, then at a low temperature of 18℃ for 2 hours, and then at a high temperature of 45℃ for 10 hours, and this cycle is repeated until the variable temperature incubation ends.

[0160] (3) Seed germination: Sprinkle the pretreated seeds obtained in step (2) evenly on the seedbed, spray 20 ml of 6-benzyladenine solution with a mass concentration of 35 mg / L per square meter of seedbed every day, spray 3 times a day for 15 days to obtain germinating seeds.

[0161] (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 3cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 25 parts peat, 12 parts Chlorella proteoglycans and 2 parts fulvic acid. The promoter, by weight, includes 10 parts paclitaxel, 5 parts D-carvone, 3 parts dodecyl aldehyde, 2 parts geraniol and 2 parts water with a salinity of 10‰.

[0162] (5) Hardening off seedlings: After the seedlings have grown to a height of more than 4 cm, the seedlings are transferred to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, a thin layer of sand is placed on top. Hardening off agent is sprayed on the seedlings and the seedlings are soaked in the hardening off agent before hardening off treatment. The hardening off substrate includes 18 parts biochar, 11 parts tea residue, 11 parts rice husk, 8 parts calcium magnesium phosphate fertilizer, 2 parts potassium sulfate and 40 parts seawater by weight.

[0163] (6) Planting: Once the seedlings have grown to 35cm in height after hardening treatment, they can be planted in the wild.

[0164] Comparative Example 9

[0165] The planting method described in Example 3 of the patent subject, application number 201911169894.6, is adopted.

[0166] Experimental Example 1: Determination of Seedling Cultivation Methods

[0167] Seashore cattail seedlings were cultivated using the seedling cultivation methods of Examples 1-3 and Comparative Examples 1-9. 100 seedlings were planted using each method. The seedling height, crown width (average width of the seedling in the north-south and east-west directions) and survival rate of the seashore cattail seedlings were measured one year after planting. The average values ​​were taken and are shown in Table 1.

[0168] Table 1. Determination of growth indicators of *Cat's Tail* seedlings.

[0169]

[0170]

[0171] Table 1 shows that the seedling survival rate of Examples 1-3 was 100%. Comparing Example 3 with Comparative Examples 1-4, it is evident that adding a seed pretreatment step is beneficial for improving seedling survival rate. A suitable pretreatment solution ratio and variable temperature cultivation accelerate seed germination and provide endogenous nutrients for subsequent seedling growth. If the variable temperature cultivation temperature sequence is changed, it reduces the accumulation of nutrients within the seed, resulting in slow germination, slow plant growth, small canopy size, and low survival rate. Comparing Example 3 with Comparative Examples 5-7, it is evident that growth fertilizer and promoters provide beneficial substances for seedling growth and development. Algal substances and plant-derived active ingredients better promote seedling growth and maintain a high survival rate. At the same time, it increases plant height and crown width. Adding saline water during seedling cultivation helps the seedlings adapt to the subsequent high-salt planting environment in the wild more quickly. Comparing Example 3 with Comparative Example 8, it can be seen that sumac powder and salsa powder contain special substances that help plants adapt to saline-alkali environments, which can help seashore cat's tail seedlings better adapt to the high-salt environment during wild planting and improve the seedlings' salt and alkali tolerance. Comparing Example 3 with Comparative Example 9, it can be seen that the seedling cultivation method of Comparative Example 9 can maintain a 100% survival rate, but the seedling growth indicators show that the plant height is lower and the crown width is smaller. Therefore, it can be seen that the seedling cultivation method of Example 3 is more suitable for the cultivation of seashore cat's tail.

[0172] Experimental Example 2: Seedlings planted in the wild

[0173] Seashore cat's tail seedlings cultivated according to the seedling cultivation method in Example 3 were planted in the wild (see details). Figure 2 , Figure 3 and Figure 4 A schematic diagram of the planting area is shown below. Figure 1 As shown;

[0174] 2.1 Confirmation of planting month

[0175] One hundred two-year-old seashore cat's tail seedlings were planted at an elevation of 3.0 meters in January, March and May 2023 on the periphery of the mangrove forest in Maniao Township, Lingao County, Hainan Province (W109°51'05",E19°54'37"). The survival rate after one year is shown in Table 2.

[0176] Table 2 Survival rate in different planting months

[0177] Planting month Planting quantity Number of surviving plants Survival rate after one year January 100 75 75％ March 100 90 90％ May 100 72 72％

[0178] As shown in Table 2, 75, 90, and 72 plants survived after one year, with survival rates of 75%, 90%, and 72%, respectively, indicating that planting in March resulted in the highest survival rate.

[0179] 2.2 Confirmation of the year the seedlings were planted

[0180] In March 2023, 100 one-year-old seedlings, 100 two-year-old seedlings, and 100 three-year-old seedlings were simultaneously planted on the periphery of the mangrove forest in Maniao Township, Lingao County, Hainan Province (W109°51'05",E19°54'37"). The results are shown in Table 3.

[0181] Table 3 Survival rate of seedlings planted in different years

[0182] Seedling year Planting quantity Number of surviving plants Survival rate after one year one-year seedlings 100 70 70％ Two-year seedlings 100 90 90％ Three-year-old seedlings 100 92 92％

[0183] As shown in Table 3, after one year, 70 one-year-old seedlings survived, 90 two-year-old seedlings survived, and 92 three-year-old seedlings survived, with survival rates of 70%, 90%, and 92%, respectively. This indicates that planting three-year-old seedlings resulted in the highest survival rate.

[0184] 2.3 Confirmation of Planting Elevation

[0185] In March 2023, three elevations were set at (W109°51'05",E19°54'37") around the mangrove forest in Maniao Township, Lingao County, Hainan Province. The elevations were 1.5m, 2.0m, and 2.5m. One hundred two-year-old seashore cat's tail seedlings were planted at each elevation. The results are shown in Table 4.

[0186] Table 4 Survival rate at different planting elevations

[0187] Elevation Planting quantity Number of surviving plants Survival rate 1.5m 100 78 78％ 2.0m 100 90 90％ 2.5m 100 60 60％

[0188] As shown in Table 4, 78, 90, and 60 plants survived after one year, with survival rates of 78%, 90%, and 60%, respectively, indicating that the survival rate was highest at an elevation of 2.0m.

[0189] In summary, the field planting method presented in this paper, combined with the growth characteristics of *Cercis chinensis*, allows for the selection of appropriate planting month, seedling age, and planting elevation. After one year, the survival rate of *Cercis chinensis* reaches as high as 90%, demonstrating that this method can significantly improve the survival rate of *Cercis chinensis*. Furthermore, this method is simple to operate and easy to promote on a large scale. Regarding the growth characteristics of *Cercis chinensis*, this method provides optimal conditions for its adaptation to the natural environment, significantly improving the survival rate of seedlings. This method also reduces the possibility of *Cercis chinensis* seeds being washed away by seawater, allowing the seeds to remain in a suitable environment and creating the necessary conditions for its natural regeneration.

[0190] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for cultivating seedlings of the endangered semi-mangrove plant, *Cercidiphyllum heliotropium*, characterized in that, Includes the following steps: (1) Seed collection: Collect the fruits of the upper half of the seaside cat's tail tree in August and September and keep them for later use; (2) Seed pretreatment: Remove the seeds from the fruit, soak the seeds in the pretreatment solution for 3-10 hours, then wrap them in gauze soaked in 0.1-0.6% emodin methyl ether and place them in an incubator for variable temperature culture for 8-12 days to obtain pretreated seeds; the pretreatment solution, by weight, includes 30-50 parts rice husk liquid, 10-16 parts 1-hydroxy-2-piperidinecarboxylic acid, 5-10 parts azelaic acid and 500-700 parts water; (3) Seed germination: Spread the pretreated seeds obtained in step (2) evenly on the seedbed, and spray 15-25 ml of 6-benzyladenine solution with a mass concentration of 20-45 mg / L per square meter of seedbed every day, 2-3 times a day, for 10-20 days to obtain germinating seeds; (4) Seedling raising: Place the germinating seeds obtained in step (3) into a seedling bag, and lay growth fertilizer and promoter in the seedling bag from bottom to top with a height of 2-5cm. After placing the pretreated seeds, cover them with a thin layer of sand, spray with water to moisten, and then carry out seedling raising treatment. The growth fertilizer, by weight, includes 20-30 parts peat, 10-15 parts Chlorella vulgaris and 1-5 parts fulvic acid. The promoter, by weight, includes 5-16 parts paclitaxel, 3-7 parts D-carvone, 1-5 parts dodecaldehyde, 1-3 parts geraniol and 1-3 parts water with a salinity of 8-12‰. (5) Hardening off seedlings: After the seedlings have grown to more than 4cm in height, transfer them to hardening off bags. Hardening off substrate is placed in the hardening off bags. After placing the seedlings, cover them with a thin layer of sand, spray hardening off agent, and then harden off the seedlings. The seedling hardening substrate comprises, by weight, 15-20 parts biochar, 10-12 parts tea residue, 10-12 parts rice husk, 7-12 parts sumac powder, 5-10 parts saltwort powder, 5-10 parts calcium magnesium phosphate fertilizer, 1-3 parts potassium sulfate, and 30-45 parts seawater. (6) Planting: After the seedlings have grown to 30-40cm in height after hardening treatment, they can be planted in the wild.

2. The seedling cultivation method according to claim 1, characterized in that, The preparation method of the pretreatment solution in step (2) is as follows: 1-hydroxy-2-piperidinecarboxylic acid, azelaic acid and water are mixed and heated to 35~40℃ while stirring to obtain a mixed solution; the mixed solution is placed in a ventilated place, and rice husk liquid is added after the temperature of the mixed solution drops to 22~25℃ to obtain the pretreatment solution.

3. The seedling cultivation method according to claim 1, characterized in that, The method for preparing the rice husk liquid in step (2) is as follows: after crushing the rice husks, mix them with a potassium hydroxide solution with a mass concentration of 1 mol / L at a solid-liquid ratio of 1 g: (10~15) mL, stir and heat to 70~80℃, let stand for 30~60 min, and filter to obtain the rice husk liquid.

4. The seedling cultivation method according to claim 1, characterized in that, The incubator settings in step (2) are as follows: first, use a medium temperature of 30-40℃ for 4-7 hours, then use a low temperature of 15-20℃ for 1-3 hours, and then use a high temperature of 42-50℃ for 8-12 hours, and repeat this cycle until the variable temperature incubation ends.

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