Cultivation nutrient solution suitable for directionally improving maximum water-holding capacity of coral island calcareous sand cyanobacteria crust

Abstract

The invention discloses a culture nutrient solution suitable for directionally improving the maximum water-holding capacity of coral island calcareous sand cyanobacteria crust. The culture nutrient solution contains 25g / L of glucose, 0.025 g / L of sodium dihydrogen phosphate, 0.1 g / L of potassium chloride, 0.05 g / L of magnesium chloride, 0.1 g / L of sodium nitrate, 0.005 g / L of ferrous chloride and the balance of water. Based on the cyanobacteria crust collected in situ, the hydrological characteristics of the cyanobacteria crust from the coral island calcareous sand are directionally improved by utilizing the artificially prepared culture nutrient solution, so that the development of the cyanobacteria crust can be promoted, the maximum water holding capacity of the crust can be improved, the use amount of an inoculation material is saved, the influence on the environment is reduced, and the economic benefit is increased. Therefore, the accumulation capacity of fresh water in the coral island is improved, a good material foundation is laid for change of an ecological environment system of the coral island, and the method has wide application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of artificial cultivation of cyanobacterial crusts, and is applicable to calcareous sand substrates. Specifically, it relates to a cultivation nutrient solution suitable for improving the maximum water holding capacity of cyanobacterial crusts on calcareous sand of coral islands. Background Art

[0002] Biological soil crusts (BSC) are complexes formed by cryptogams such as algae, lichens, mosses and soil microorganisms through secretions, rhizoids, hyphae, etc. cemented with surface soil particles. They are the most important surface coverings in desert and polar regions, and their coverage can be as high as 60% - 70% in the Loess Plateau region. Biological soil crusts profoundly affect the material cycle and energy exchange processes of the surface soil, significantly improve the physical, chemical and biological properties of the surface soil, and have multiple ecological functions such as wind prevention and sand fixation, water and heat regulation, carbon and nitrogen sequestration, improvement of soil enzyme activity and increase of biodiversity, playing an important role in the soil and vegetation restoration of fragile ecological areas. Biological soil crusts have extremely strong stress resistance and can adapt to extremely arid and barren environments, and thus become pioneer taxa driving soil formation and primary succession.

[0003] Biological soil crusts are the most important surface coverings on tropical coral islands. The main dominant genus is Chroococcidiopsis, which belongs to the phylum Cyanobacteria. Previous studies have shown that the biological soil crusts on tropical coral islands are all in the primary stage of succession, also known as cyanobacterial crusts. The main component of tropical coral islands is calcareous coral sand, with a carbonate content as high as 95%, and has unique environmental characteristics, including the lack of real soil and fresh water resources, high salinity and alkalinity, high temperature, and strong and long-term ultraviolet radiation. Almost no plant species can grow and settle on tropical coral islands. However, the presence of biological soil crusts can effectively enhance the soil and water erosion resistance ability, reduce soil and water loss, and provide good biological conditions for improving these island substrates to create an environment suitable for plant growth, especially the accumulation of fresh water resources. Research shows that biological soil crusts can increase rainfall interception, promote condensation water capture, enhance the water holding capacity of the soil surface layer, reduce water infiltration into the deep layer, improve the growth environment of herbaceous plants, and promote the rapid succession of artificial vegetation communities. At present, biological soil crusts have been widely applied to ecological restoration projects in desert areas, but the research and application in the terrestrial environment of coral islands with calcareous sand as the substrate are still in their infancy. Due to its good fresh water accumulation ability and the function of promoting natural vegetation succession, the cultivation method based on improving the maximum water holding capacity of biological soil crusts has good application prospects. Summary of the Invention

[0004] In view of the fact that there is no relevant cultivation nutrient solution for specifically improving the maximum water holding capacity of cyanobacterial crusts in the environment of tropical coral islands at home and abroad, the present invention aims at the characteristics of large rainfall and concentrated distribution in Chinese tropical coral islands, and based on the principle that the native biota can ensure the maximum adaptability, uses in-situ biological crusts as the cultivation object, artificially prepares the cultivation nutrient solution, promotes the development of cyanobacterial crusts on calcareous coral sand and improves their maximum water holding capacity.

[0005] The purpose of the present invention is to provide a cultivation nutrient solution suitable for directionally improving the maximum water holding capacity of cyanobacterial crusts on coral islands. By using cyanobacterial crusts derived from tropical coral islands and inoculating them on calcareous coral sand under a simulated natural environment of coral islands, adding this cultivation nutrient solution, a method is achieved to obtain artificially cultivated cyanobacterial crusts with high water holding capacity in indoor cultivation with the least inoculation amount.

[0006] The cultivation nutrient solution described above contains glucose, sodium dihydrogen phosphate, potassium chloride, magnesium chloride, sodium nitrate, ferrous chloride and water.

[0007] Preferably, the cultivation nutrient solution contains: 25 g / L of glucose, 0.025 g / L of sodium dihydrogen phosphate, 0.1 g / L of potassium chloride, 0.05 g / L of magnesium chloride, 0.1 g / L of sodium nitrate, 0.005 g / L of ferrous chloride, and the balance is water.

[0008] The second purpose of the present invention is to provide the application of the above-mentioned cultivation nutrient solution in rapidly cultivating cyanobacterial crusts and / or improving their maximum water holding capacity.

[0009] The present invention is applicable to the cultivation process for improving the maximum water holding capacity of cyanobacterial crusts growing on calcareous sand as the substrate, and includes the following steps:

[0010] a. The raw material is cyanobacterial crusts on coral islands growing on calcareous sand as the substrate. After natural air-drying, it is ground to make seed soil similar to the biological community of native biological crusts.

[0011] b. The seed soil is evenly spread and inoculated on calcareous sand for cultivation. After the start of cultivation, at least one spraying of the artificially prepared nutrient solution is carried out, and regular watering is carried out at other times to maintain the moisture content of the calcareous sand at 10% - 15%.

[0012] Preferably, in step a, the collected cyanobacterial crusts on coral islands are air-dried at room temperature (25°C) and then ground to make the inoculation material (seed soil).

[0013] Preferably, in step b, the inoculation amount of the inoculation material is 240 g / m 2 , which is much lower than the dosage in early research, and as much as possible reduces the damage to in-situ biological crusts.

[0014] Preferably, in step b, the water content of the calcareous sand is maintained at 14%.

[0015] Preferably, in step b, after spray-fixing the inoculation material, the artificially prepared nutrient solution is sprayed only once.

[0016] The nutrient solution for cultivating cyanobacterial crust provided by the present invention uses the in-situ cyanobacterial crust collected from tropical coral islands, dries it in the shade and grinds it to make an inoculation material. Nutrients and trace mineral elements that promote the growth of cyanobacteria are selected as the culture solution, and the unit inoculation amount is also considered as an influencing factor. Aiming to minimize the damage to the in-situ environment, artificial directional cultivation of cyanobacterial crust is carried out to obtain the cultivation effect with the maximum water holding capacity.

[0017] This invention is carried out in an artificial climate cultivation chamber. According to the long-term monitoring results of tropical coral islands, the temperature, relative air humidity, photoperiod, and light intensity in the artificial climate chamber are set respectively as (day / night): 33 / 28.5 °C, 68% / 80%, 14 / 10 h, 13000 / 0 lux. At the same time, the cultivation box is regularly sprayed manually every day to ensure that the water content of the calcareous sand in the cultivation box is maintained at 14%.

[0018] Before inoculation, first carry out water mist treatment on the calcareous sand in the cultivation box to make it in a wet state; then evenly spread the ground cyanobacterial crust seed soil from the coral island on the calcareous sand, and then carry out wet treatment on the calcareous sand again. The inoculation amount of the inoculation material is 240 g / m 2 ; After 6 hours, evenly spray the prepared artificially prepared nutrient solution on the surface of the inoculation material at one time. The artificially prepared nutrient solution contains: glucose, sodium dihydrogen phosphate, potassium chloride, magnesium chloride, sodium nitrate, ferrous chloride and water.

[0019] After 120 days of indoor cultivation, obvious cyanobacterial crusts are formed on the calcareous sand in the cultivation box ( Figure 1 ). The maximum water holding capacity of all the inoculated cyanobacterial crusts (and adding the artificially prepared nutrient solution) developed to form crusts is significantly higher than that of the blank control group inoculated with cyanobacterial crusts but without adding nutrient solution (the maximum water holding capacity of the control group is 30.55%), and the higher range is 2.66% - 9.07%.

[0020] Main advantages of the present invention: 1. Using in-situ samples as inoculation materials and acclimating them in a simulated environment can maximize the adaptability of artificially cultivated biological soil crusts to the in-situ environment; 2. The preparation of the nutrient solution is mainly targeted at the needs of cyanobacteria development, and the increase in the water holding capacity of the biological soil crust depends on the development state of cyanobacteria. The nutrient solution of the present invention can maximize the promotion of cyanobacteria development, thereby increasing the maximum water holding capacity of the soil crust, reducing the addition of other substances, saving cultivation costs, and reducing the impact on and damage to the environment; 3. Currently, there is no specific nutrient solution specifically for increasing the maximum water holding capacity of cyanobacteria soil crusts at home and abroad. The present invention can fill the technical gap in this field.

[0021] The present invention can be directly applied to the cultivation of in-situ cyanobacteria soil crusts and the improvement of their maximum water holding capacity, with a clear purpose and a relatively fast cultivation speed. It can be applied to both in-situ cyanobacteria soil crusts and indoor artificial cyanobacteria soil crust cultivation, and has broad application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 are the apparent change characteristics of artificially cultivated cyanobacteria soil crusts on the 1st, 60th, and 120th days of cultivation respectively.

[0023] Figure 2 is the net increase in the maximum water holding capacity at the end of cultivation for each combination of nutrient formula and inoculation amount.

[0024] Figure 3 is the development effect of artificial cyanobacteria soil crusts at the end point of the indoor cultivation effect test, including combination 31 and the optimal experimental combination K. DETAILED DESCRIPTION OF THE INVENTION

[0025] The following examples are further illustrations of the present invention, rather than limitations thereof.

[0026] Example 1: Preparation of a cultivation nutrient solution for directionally increasing the maximum water holding capacity of cyanobacteria soil crusts on coral islands

[0027] A method of the present invention for ensuring that artificial cultivated cyanobacteria soil crusts with high water holding capacity are obtained by directional cultivation indoors using a cultivation nutrient solution prepared from different concentration ratios of carbon source, nitrogen source, phosphorus source, and potassium, magnesium, and iron elements in combination with the optimal inoculation amount from the cyanobacteria soil crust seed soil sourced from tropical coral islands under a simulated coral island natural environment. The specific operations are carried out according to the following steps:

[0028] 1. Considering 7 factors including inoculation amount, glucose, sodium nitrate, disodium hydrogen phosphate, potassium chloride, magnesium chloride, and ferrous chloride, each factor is set at 4 levels, and then using a seven-factor four-level orthogonal table, a total of 32 different combinations of nutrient ratios and inoculation amounts are obtained. The specific concentrations and nutrient combinations are shown in Table 1 and Table 2 respectively.

[0029] Table 1 Types of Nutrients, Mineral Elements, and Their Corresponding Different Concentrations and Different Inoculation Amounts

[0030]

[0031] Table 2 Combinations of Nutrient Components and Inoculation Amounts Formed Using an Orthogonal Array

[0032]

[0033]

[0034]

[0035] 2. Treatment of inoculation materials: Collect well-developed cyanobacterial crusts on tropical coral islands and then air-dry them naturally at room temperature (25°C); grind the air-dried cyanobacterial crusts and prepare experimental inoculation materials for subsequent experiments.

[0036] 3. Fill the cultivation box with in-situ collected calcareous sand. The net weight of the sand is 1320 g (dry weight) and the thickness is 35 mm; control the average moisture content of the calcareous sand to 14%, and the initial water addition is 220 g; then, use a self-made spraying device to evenly spread the inoculation materials on the calcareous sand and moisten them with water mist to fix the inoculation materials and start the cultivation.

[0037] 4. According to the long-term monitoring results of tropical coral islands, set the temperature, relative air humidity, photoperiod, and light intensity in the artificial climate chamber to (day / night): 33 / 28.5°C, 68% / 80%, 14 / 10 h, 13000 / 0 lux. At the same time, regularly supplement the lost water every day to maintain the moisture content of the surface calcareous sand in the cultivation box at 14%. 24 hours after the start of the experiment, evenly spread 40 mL of the mixed culture solution of nutrients and mineral elements prepared in advance on the substrate soil. The specific nutrient concentrations and inoculation amounts of the culture solution (the inoculation amounts are all calculated based on the amount of seed soil in the inoculation materials) are shown in Table 2.

[0038] 5. The artificial cultivation period is 120 days. During the entire experimental process, only one artificial cultivation nutrient solution is sprayed. After 120 days of indoor cultivation, it is found that obvious cyanobacterial crusts have formed on the calcareous sand in all cultivation boxes ( Figure 1 ).

[0039] 6. During the experiment, measure the maximum water-holding capacity of the crust samples at the start and end of the experiment. The specific method is as follows:

[0040] Use a core cutter (100 cm 3)Collect biological soil crust samples and seal both ends. When conducting the measurement, first remove the upper and lower covers of the core cutter. Replace one end with a bottom cover with mesh holes and filter paper, and keep the other end open. Then, place the end with mesh holes and filter paper downward into a porcelain dish (or flat basin), inject water into the porcelain dish and keep the water level up to the upper edge of the core cutter, allowing it to absorb water for 2 hours. At this time, all non-capillary pores and capillary pores in the core cutter soil are filled with water. Cover the upper cover, take it out horizontally, and immediately place the end with mesh holes and filter paper downward on a flat dish covered with dry sand to absorb the excess water, and then immediately weigh it (A). Finally, take out a representative part (20g) of the soil sample in the core cutter and put it into an aluminum box to measure the soil moisture content. Use this soil moisture content to convert the wet soil in the core cutter into dry soil weight, and thus calculate the maximum water holding capacity.

[0041] The maximum water holding capacity of biological soil crust % = (A - W - Wcore) / W * 100%;

[0042] In the formula, W is the dry soil weight (g) in the core cutter; Wcore is the weight of the core cutter (g).

[0043] The measurement of the maximum water holding capacity of artificial cyanobacteria soil crust found that ( Figure 2 ), the net increment of experimental treatment 31 is the highest, which is 7.08 ± 0.029%, but there is no significant difference from the net increments of experimental group 3 and experimental group 5. Among all experimental groups, the experimental group with an inoculation amount of 240g / m 2 has the highest average increase in the maximum water holding capacity, which is 5.14 ± 1.44%. Through the variance analysis of the orthogonal experiment results, it can be seen that 4 factors have significant effects on the water holding capacity of the samples (P < 0.05), namely sodium nitrate, sodium dihydrogen phosphate, potassium chloride, and inoculation amount. Among them, sodium nitrate has the greatest effect on the water holding capacity of the soil crust, and ferrous chloride has the smallest effect. The specific influence degree is: sodium nitrate > sodium dihydrogen phosphate > potassium chloride > inoculation amount > glucose > magnesium chloride > ferrous chloride. In addition, the optimal concentration values of each factor are as follows: glucose concentration: T2 > T3 > T4 > T1, sodium nitrate concentration: T1 > T3 > T2 > T4, sodium dihydrogen phosphate concentration: T2 > T1 > T4 > T3, potassium chloride concentration: T1 > T4 > T3 > T2, magnesium chloride concentration: T1 > T3 > T2 > T4, ferrous chloride concentration: T3 > T1 > T4 > T2, inoculation amount: T1 > T2 > T3 > T4. Therefore, in terms of the maximum water holding capacity, the best combination of the cultivation nutrient solution for directionally improving the maximum water holding capacity of cyanobacteria soil crust on coral islands is: sodium nitrate concentration 0.1g / L + sodium dihydrogen phosphate concentration 0.025g / L + potassium chloride concentration 0.1g / L + inoculation amount 240g / m 2 + glucose concentration 25g / L + magnesium chloride concentration 0.05g / L + ferrous chloride concentration 0.005g / L.

[0044] Example 2: Indoor test of the cultivation effect of the cultivation nutrient solution

[0045] Carry out the indoor cultivation experiment according to steps 2-5 in Example 1. In the indoor test experiment, there are two experimental groups in total, and their combination is combination 31 in Example 1 (sodium nitrate concentration 0.1 g / L + sodium dihydrogen phosphate concentration 0.025 g / L + potassium chloride concentration 0.1 g / L + inoculation amount 720 g / m 2 + glucose concentration 25 g / L + magnesium chloride concentration 0.1 g / L + ferrous chloride concentration 0.005 g / L) and experimental group K obtained through orthogonal experiments (sodium nitrate concentration 0.1 g / L + sodium dihydrogen phosphate concentration 0.025 g / L + potassium chloride concentration 0.1 g / L + inoculation amount 240 g / m 2 + glucose concentration 25 g / L + magnesium chloride concentration 0.05 g / L + ferrous chloride concentration 0.005 g / L). During the whole experimental process, the artificially prepared cultivation nutrient solution is sprayed only once. The test period is 120 days, and the maximum water holding capacity of the artificial cyanobacterial crust is measured at the beginning and end of the experiment.

[0046] At the end of the indoor cultivation effect test experiment, the development effects of the artificial cyanobacterial crusts of combination 31 and experimental group K are shown in Figure 3 .

[0047] Analyze the results of the indoor test experiment and find that the average net increase in the maximum water holding capacity of combination 31 is 7.11 ±

[0048] 0.53%, while the average net increase of experimental group K is 7.19 ± 0.89%, and there is no significant difference between the two experimental groups, but the average value of experimental group K is slightly higher than that of experimental group 31. The difference in the maximum water holding capacity of the artificial cyanobacterial crusts of the two types of combinations is not obvious, but the inoculation amount of experimental group K is very small, indicating that the artificially prepared cultivation nutrient solution has a significant directional promotion effect on the maximum water holding capacity of the artificial cyanobacterial crust and can reduce the usage amount of environmental samples, directly reducing the damage to the environment.

[0049] The cultivation nutrient solution provided by the present invention can act on the in-situ cyanobacterial crust and can also be applied to the indoor cultivation of artificial cyanobacterial crusts, thereby improving the fresh water accumulation capacity of coral islands and laying a good material foundation for the change of the coral island ecological environment system. Therefore, the present invention has broad application value.

[0050] The above-described embodiments are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary engineering and technical personnel in the art to the technical solutions of the present invention should fall within the protection scope determined by the claims of the present invention.

Claims

1. A nutrient solution for increasing the maximum water holding capacity of coral island cyanobacteria crusts, characterized in that: Contains dextrose, sodium dihydrogen phosphate, potassium chloride, magnesium chloride, sodium nitrate, ferrous chloride and water.

2. The cultivation nutrient solution according to claim 1, characterized in that: The cultivation nutrient solution contains: 25 g / L glucose, 0.025 g / L sodium dihydrogen phosphate, 0.1 g / L potassium chloride, 0.05 g / L magnesium chloride, 0.1 g / L sodium nitrate, 0.005 g / L ferrous chloride, and the balance is water.

3. Application of the cultivation nutrient solution described in claim 1 or 2 in rapidly cultivating cyanobacterial crust and / or improving its maximum water holding capacity.

4. The use according to claim 3, characterized in that: The following steps are involved: a. The raw material is coral island cyanobacteria crust grown on calcareous sand substrate, which is naturally dried and then ground to make seed soil similar to the protist biocrust community; b. Spread the seed soil evenly on the calcareous sand for cultivation. After the start of cultivation, spray the artificially prepared nutrient solution at least once, and water regularly during the rest of the time to maintain the moisture content of the calcareous sand at 10% to 15%.

5. The use according to claim 4, characterized in that: In step a, the collected coral island cyanobacteria crusts are placed in the shade for drying at room temperature, and then ground to prepare seed soil.

6. The use according to claim 4, characterized in that: In step b, the inoculation amount of the seed soil is 240g / m 2 .

7. The use according to claim 4, characterized in that: In step b, the cultivation conditions are: according to day / night, the temperature is 33 / 28.5°C, the relative air humidity is 68% / 80%, the photoperiod is 14 / 10h, and the light intensity is 13000 / 0lux.

8. The use according to claim 4, characterized in that: In step b, the water content of the calcareous sand is maintained at 14%.

9. The use according to claim 4, characterized in that: In step b, after the seed soil is sprayed and fixed, the artificially prepared nutrient solution is sprayed once and only once.

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