Salinity regulation and control seedling raising method for hibiscus syriacus

Abstract

The invention discloses a salinity regulation and control seedling culture method for hibiscus syriacus, and belongs to the technical field of hibiscus syriacus seedling culture. The method comprises the following steps: (1) seed treatment; (2) preparing a substrate; (3) after sowing, culturing in a greenhouse; (4) transplanting and salinity control: a) when the seedlings grow to have 3-4 true leaves, transplanting the seedlings into a nutrition bag, adding 0.4-0.6 wt% of a microbial liquid into the matrix at the same time, the microbial liquid containing nitrogen-fixing bacteria Azobacter chrocococcus and phosphate-solubilizing bacteria Bacillus licheniformis, and the total number of viable bacteria being greater than or equal to 1 * 10 < 9 > CFU / mL; after transplanting, carrying out drip irrigation with brackish seawater, and spraying a 0.1% monopotassium phosphate solution on leaf surfaces every half a month for three times in total; b) directly carrying out drip irrigation on brackish seawater in the nutrition bag; and (5) outdoor cold-resistant treatment: 30 days before winter, spraying 0.2-0.5 L of 0.2-0.4 wt% potassium sulfate aqueous solution to leaf surfaces for each plant, spraying once every 6-8 days, and spraying 3-5 times in total. Through salinity gradient domestication and use of the microbial agent, the biomass loss rate of the hibiscus syriacus under the salinity of 0.5% is remarkably reduced, and the annual increment of the plant height is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of cultivating Hibiscus sempervirens seedlings, and in particular relates to a salinity-controlled seedling cultivation method for Hibiscus sempervirens. Background Art

[0002] Thepesia populneoides is a small, evergreen tree in the Malvaceae family, growing 6-10 meters tall. Its leaves are ovate and heart-shaped at the base. The color of its flowers changes with time of day, from yellow in the morning to yellow in the afternoon. Its pedicels are 6-9 cm long, and its capsules are nearly spherical with a leathery exocarp. It blooms year-round. Commonly found within the inner margins of mangroves and along coastal forests, the plant is an important semi-mangrove species in Wenchang and Sanya, Hainan Province, my country. In 2006, it was listed in the Hainan Provincial List of Key Protected Wild Plants. Thepesia populneoides is a light-loving plant that prefers warm, humid environments and is tolerant of humidity. It has both ecological revetment and ornamental uses, as well as medicinal value (its leaves and bark contain anti-inflammatory and anti-tumor active ingredients). However, due to its seed set rate exceeding 95% and its leathery exocarp resulting in poor water permeability (water absorption rate of 0.02 g / h), conventional seedling cultivation has a very low success rate, with a natural germination rate of <10%. Traditional mangrove seedling cultivation mostly uses direct seeding on tidal flats, but the long-stemmed hibiscus seedlings are sensitive to salinity (biomass decreases by 30% when >5‰) and have weak cold resistance (leaf frost damage rate >40% below 5°C), resulting in a transplant survival rate of less than 50%.

[0003] Among existing semi-mangrove seedling cultivation technologies, trials with the introduction of Hibiscus truncatum (a related genus) have shown that salinity control (≤3‰) and cold-hardening are key. In container-based cultivation of Hibiscus truncatum, seed soaking in a gibberellin aqueous solution and optimizing the substrate formulation can significantly improve the emergence rate. Hibiscus truncatum, a semi-mangrove plant with both coastal protection and medicinal value, is in high demand and requires high quality seedlings. Conventional seeding has an extremely low success rate, necessitating the development of a targeted seedling cultivation system to promote its widespread application in mangrove ecological restoration and the development of its medicinal value. Summary of the Invention

[0004] The present invention provides a salinity-controlled seedling cultivation method for Hibiscus sempervirens, which comprises the following steps:

[0005] (1) Seed treatment: Soak the seeds in a 150-250 ppm gibberellin aqueous solution for 4-8 hours, then soak in clean water for at least 20 hours;

[0006] (2) Substrate preparation: peat soil, river sand, decomposed straw powder, and vermiculite are mixed in a volume ratio of 3-5:2-4:1-3:0.5-1.5. After mixing, 8-12g of ternary compound fertilizer is added per kilogram of substrate, and then 2.5-3.5wt% of ferrous sulfate is added and the mixture is piled and covered for 6-8 days;

[0007] (3) Seeding, culture temperature 25-28°C;

[0008] (4) Transplanting and salinity control:

[0009] a) When the seedlings grow to 3-4 true leaves, they are transplanted into nutrient bags. The substrate is the same as in step (2), and 0.4-0.6 wt% microbial solution containing nitrogen-fixing bacteria Azotobacter chroococcum and phosphate-solubilizing bacteria Bacillus licheniformis is added to the substrate. The total number of viable bacteria is ≥1×10 9 CFU / mL, the ratio of the number of nitrogen-fixing bacteria to that of phosphate-solubilizing bacteria was 1-2:1-2; after transplanting, drip irrigation with brackish seawater was applied, and 0.1% potassium dihydrogen phosphate solution was sprayed on the leaves every half month for a total of 3 times;

[0010] b) drip irrigation with brackish seawater, ambient temperature 25-28°C;

[0011] Direct drip irrigation in the nutrient bag, 1-2L per plant each time, irrigate 2 to 3 times a day, the specific drip irrigation process is as follows:

[0012] ① Adaptation period: 1-3 months: fresh water, salinity 0‰;

[0013] ② Transition period: 4-6 months: fresh water and 1-2‰ sea water alternate;

[0014] ③ Strengthening period 7-8 months: 2-3‰ seawater;

[0015] ④ Stable period 9-11 months: 3-4‰ seawater;

[0016] ⑤Maturity period 12-14 months: 4-5‰ seawater;

[0017] After drip irrigation is completed, transplant the nutrient bags outdoors to exercise them against the cold;

[0018] (5) Outdoor cold resistance treatment: 30 days before winter, spray the leaves with 0.2-0.4 wt% potassium sulfate aqueous solution, 0.2-0.5 L per plant, once every 6-8 days, for a total of 3-5 times.

[0019] In one embodiment of the present invention, the concentration of the gibberellin aqueous solution in step (1) is 200 ppm, the soaking time is 6 hours, and then soaking in clean water for 24 hours.

[0020] In one embodiment of the present invention, the volume ratio of peat soil, river sand, decomposed straw powder and vermiculite in step (2) is 4:3:2:1.

[0021] In one embodiment of the present invention, the amount of the ternary compound fertilizer added in step (2) is 10 g, and the amount of ferrous sulfate added is 3 wt %.

[0022] In one embodiment of the present invention, the amount of microbial liquid added in step (4) is 0.5 wt%.

[0023] In one embodiment of the present invention, during the drip irrigation in step (4), the flow rate is 2.0-4.0 L / h, and the single irrigation time is 30 minutes.

[0024] In one embodiment of the present invention, in step (5), the leaves are initially sprayed with a 0.3 wt% potassium sulfate aqueous solution.

[0025] In one embodiment of the present invention, in step (5), 0.3 L of potassium sulfate aqueous solution is sprayed on each plant.

[0026] In one embodiment of the present invention, the potassium sulfate aqueous solution is sprayed once every 7 days in step (5), and sprayed 4 times in total.

[0027] Mechanism of action:

[0028] Seed soaking in a gibberellin aqueous solution breaks dormancy, softens the seed coat, and improves water absorption and germination uniformity. A strategically formulated mix of peat, river sand, composted straw powder, and vermiculite in the substrate optimizes moisture and air conditions, ensuring slow-release nutrients. Combined with a three-element compound fertilizer and microbial solution, it promotes root development and enhances stress resistance. Stepwise salinity control (from 0‰ to 3‰ to 5‰ seawater) simulates natural salinity conditions, enhancing seedling cell ion regulation and salt tolerance.

[0029] During the cold-resistant seedling hardening period, the fertilization structure and light intensity are adjusted to improve the stability of the cell membrane and the activity of stress-resistant enzymes, thereby enhancing cold resistance.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) Mechanical exocarp removal and seed soaking in gibberellin solution significantly increased the germination rate (60% vs 10%);

[0032] (2) Through salinity gradient acclimation, the ion compartmentalization ability of seedlings was improved, and the biomass loss rate was ≤15% at a salinity of 5‰;

[0033] (3) Microbial agents promote the activation of nitrogen and phosphorus in the rhizosphere, increasing the annual increase in plant height by 20%-30%;

[0034] (4) After hardening the seedlings, the critical temperature of the seedlings dropped to 0℃, making them suitable for introduction to the northern edge, such as the coastal areas of Fujian. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention is a flowchart of the seedling cultivation of Hibiscus sempervirens.

[0036] Figure 2The comparison results of seedling biomass under different salinities in Example 1 (drip irrigation for 3 months). DETAILED DESCRIPTION

[0037] Example 1

[0038] This embodiment provides a method for growing seedlings of Hibiscus sempervirens under salinity control, the steps of which are as follows:

[0039] (1) Seed treatment: Mature fruits were collected from Sanya, Hainan, and plump seeds were selected after shelling. The seeds were soaked in a 200 ppm gibberellin aqueous solution for 6 hours and then soaked in clean water for 24 hours.

[0040] (2) Substrate preparation: peat soil: river sand: decomposed straw powder: vermiculite = 4:3:2:1 (volume ratio). After mixing, add 10g of ternary compound fertilizer (N:P2O5:K2O = 15:15:15) per kilogram of substrate, and then mix in 3% by mass of ferrous sulfate and pile it for 7 days;

[0041] The preparation process for the decomposed straw powder is as follows: pulverize rice straw into a 1.0mm powder, sterilize with high-pressure wet heat at 121°C, and dry at 60°C for later use. Add a straw composting agent to the powder at a mass ratio of 1:200. Place the powder in a 120L plastic barrel, cover the barrel with gauze, and allow it to ferment naturally at room temperature. Composting is complete after 15-20 days (in summer) or 35-50 days (in winter). The straw composting agent is manufactured by Shanghai Lianye Agricultural Technology Co., Ltd., and they market their "Gulin" brand straw composting agent.

[0042] (3) Sowing management: Sow seeds in a 50-hole tray (hole diameter 5 cm × 10 cm), 1-2 seeds per hole, cover with 0.5 cm of substrate, press lightly and spray until moist, cover with non-woven fabric to keep moisture, and cultivate in a greenhouse at 25°C. The emergence rate reaches 92% in 15 days;

[0043] (4) Transplanting and salinity control:

[0044] a) When the seedlings have 3-4 true leaves, transplant them into nutrient bags with a diameter of 15 cm and a height of 20 cm. Add 0.5 wt% microbial solution (nitrogen-fixing bacteria Azotobacter chroococcum + phosphate-solubilizing bacteria Bacillus licheniformis, with a viable count of ≥ 1 × 10 9 CFU / ml, the ratio of the number of live nitrogen-fixing bacteria to that of live phosphate-solubilizing bacteria is 1:1). After transplanting, drip irrigation is used to control watering, and 0.1% potassium dihydrogen phosphate solution is sprayed on the leaves every half month for a total of 3 times.

[0045] b) drip irrigation with brackish seawater (salinity gradient: 0‰ → 3‰ → 5‰), ambient temperature 25-28°C;

[0046] Direct drip irrigation in the nutrient bag, each time 1-2L per plant (per bag), irrigation frequency 2 to 3 times a day, drip flow 2.0-4.0L / h, single irrigation time 30 minutes. The initial drip irrigation salinity of the bagged seedlings is controlled at 0-3‰, and gradually increased to 4-5‰ in the middle and late stages. After the 5‰ salt water drip irrigation is completed, the nutrient bag is transplanted outdoors for cold resistance training:

[0047] ① Adaptation period (1-3 months): fresh water, salinity 0‰;

[0048] ② Transition period (4-6 months): fresh water and 1‰ seawater (brackish seawater) alternate;

[0049] ③ Strengthening period (7-8 months): 2‰ seawater (brackish seawater);

[0050] ④ Stable period (9-11 months): 3‰ seawater (brackish seawater);

[0051] ⑤Maturity period (12-14 months): 5‰ seawater (brackish seawater);

[0052] Figure 2 Comparison results of seedling biomass under different salinities;

[0053] (5) Outdoor cold-resistant treatment: 30 days before winter (average monthly temperature 13-15°C), spray the leaves with 0.3 wt% potassium sulfate aqueous solution, 0.2-0.5 L per plant, once every 7 days, for a total of 4 sprays, covering the entire cold-resistant induction period (30 days), and gradually remove the sunshade net; the changes in leaf electrolyte permeability before and after cold-resistant treatment are shown in the following table:

[0054] Table 1

[0055]

[0056]

[0057] (6) Seedling effect: The average plant height of 1.5-year-old seedlings was 48 cm, the survival rate was 85% in a salinity of 5‰ environment, and no cold damage symptoms occurred after 5 days of low temperature treatment at 0℃.

[0058] Comparative Example 1

[0059] The operation steps of this comparative example are the same as those of Example 1, except that the exocarp and seeds are not treated in any way and are directly sown. The comparative data of this comparative example and Example 1 are as follows:

[0060] Table 2

[0061] Treatment group Germination rate Example 1 60％ Comparative Example 1 10％

[0062] Comparative Example 2

[0063] The operation steps of this comparative example are the same as those of Example 1, except that:

[0064] (1) The seeds were not treated with the exocarp or soaked, but were directly sown in the same medium as in Example 1. The natural emergence rate under greenhouse conditions was 10%.

[0065] (2) The salinity is not adjusted incrementally and irrigation is directly carried out at 3‰.

[0066] (3) Omit the microbial culture solution.

[0067] Table 3

[0068] Treatment group Salinity control microbial agents Overwintering survival rate Example 1 Step-by-step have 85％ Comparative Example 2 Fixed 3‰ none 63％

[0069] The above comparative example illustrates:

[0070] (1) Mechanical exocarp removal plus gibberellin soaking significantly increased germination rate (60%-92% vs 10%);

[0071] (2) The salinity increase treatment improved the ion regulation ability of seedlings and significantly reduced biomass loss;

[0072] (3) Microbial liquid promotes the activation of rhizosphere nutrients, increases plant height and seedling rate;

[0073] (4) Cold-resistant seedling hardening improves the survival rate over the winter and is suitable for introduction into the northern margin.

[0074] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for raising seedlings of Hibiscus longipes by controlling salinity, characterized in that: The following steps are involved: (1) Seed treatment: Soak the seeds in a 150-250 ppm gibberellin aqueous solution for 4-8 hours, then soak in clean water for at least 20 hours; (2) Substrate preparation: peat soil, river sand, decomposed straw powder, and vermiculite are mixed in a volume ratio of 3-5:2-4:1-3:0.5-1.

5. After mixing, 8-12g of ternary compound fertilizer is added per kilogram of substrate, and then 2.5-3.5wt% of ferrous sulfate is added and the mixture is piled and covered for 6-8 days; (3) Seeding, culture temperature 25-28°C; (4) Transplanting and salinity control: a) When the seedlings grow to 3-4 true leaves, they are transplanted into nutrient bags. The substrate is the same as in step (2), and 0.4-0.6 wt% microbial solution containing nitrogen-fixing bacteria Azotobacter chroococcum and phosphate-solubilizing bacteria Bacillus licheniformis is added to the substrate. The total number of viable bacteria is ≥1×10 9 CFU / mL, the ratio of the number of nitrogen-fixing bacteria to that of phosphate-solubilizing bacteria was 1-2:1-2; after transplanting, drip irrigation with brackish seawater was applied, and 0.1% potassium dihydrogen phosphate solution was sprayed on the leaves every half month for a total of 3 times; b) drip irrigation with brackish seawater, ambient temperature 25-28°C; Direct drip irrigation in the nutrient bag, 1-2L per plant each time, irrigate 2 to 3 times a day, the specific drip irrigation process is as follows: ① Adaptation period: 1-3 months: fresh water, salinity 0‰; ② Transition period: 4-6 months: fresh water and 1-2‰ sea water alternate; ③ Strengthening period 7-8 months: 2-3‰ seawater; ④ Stable period 9-11 months: 3-4‰ seawater; ⑤Maturity period 12-14 months: 4-5‰ seawater; After drip irrigation is completed, transplant the nutrient bags outdoors to exercise them against the cold; (5) Outdoor cold resistance treatment: 30 days before winter, spray the leaves with 0.2-0.4 wt% potassium sulfate aqueous solution, 0.2-0.5 L per plant, once every 6-8 days, for a total of 3-5 times.

2. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 1, wherein: The concentration of the gibberellin aqueous solution in step (1) is 200 ppm, the seeds are soaked for 6 hours, and then soaked in clean water for 24 hours.

3. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 2, wherein: In step (2), the volume ratio of peat soil, river sand, decomposed straw powder and vermiculite is 4:3:2:

1.

4. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 3, characterized in that: In the step (2), the amount of the ternary compound fertilizer added is 10 g, and the amount of ferrous sulfate added is 3 wt %.

5. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 4, characterized in that: The amount of microbial liquid added in step (4) is 0.5 wt%.

6. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 5, characterized in that: During drip irrigation in step (4), the flow rate is 2.0-4.0 L / h, and the single irrigation time is 30 minutes.

7. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 6, characterized in that: In the step (5), the leaves are initially sprayed with a 0.3 wt% potassium sulfate aqueous solution.

8. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 7, characterized in that: In the step (5), 0.3 L of potassium sulfate aqueous solution was sprayed on each plant.

9. The salinity-controlled seedling raising method of Hibiscus longipedus according to claim 8, characterized in that: In the step (5), the potassium sulfate aqueous solution is sprayed once every 7 days, and a total of 4 times.

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