Overwintering preservation method for azolla seedlings in rice field

Abstract

The invention relates to the technical field of azolla cultivation, in particular to an overwintering preservation method of azolla seedlings in a rice field, which utilizes a greenhouse or a greenhouse to preserve azolla seedlings, covers a light-transmitting plastic film to improve local environment temperature of azolla growth so as to avoid freeze injury stress on azolla caused by low temperature, and meanwhile, applies special azolla overwintering fertilizer to prevent overwintering of azolla. According to the method, azolla seedlings are stored in a nearby field, and after the azolla overwinter smoothly, the azolla seedlings are directly transferred to the nearby field for large-scale propagation; therefore, the problems of energy consumption and cost of transportation of azolla seedlings in different places and broken azolla and rotting in the transportation process are avoided, and the survival rate of the azolla seedlings can be effectively increased.

Description

Technical Field

[0001] The invention relates to the technical field of Azolla cultivation, and in particular to a method for overwintering storage of Azolla seedlings in rice fields. Background Art

[0002] Azolla is a symbiotic aquatic fern-algae organism that, in symbiosis with the nitrogen-fixing alga Anabaena within its leaf cavities, possesses a highly potent biological nitrogen-fixing capacity. Introducing Azolla into rice fields, utilizing its biological nitrogen fixation to provide nitrogen to rice, can effectively alleviate nitrogen pollution in farmland and increase rice yields.

[0003] Currently, my country's traditional rice field azolla cultivation model relies primarily on the natural overwintering of Azolla in the paddy field water, lacking measures to strengthen and preserve its seeds. However, Azolla is intolerant to low temperatures. Typically, when temperatures drop below -4°C, it suffers severe freezing damage and gradually dies, making it unable to survive the harsh winter under natural conditions. When Azolla seedlings lack nutrient accumulation, they become weak, prone to reddening, and have weak resistance, making them susceptible to rot. Furthermore, Azolla seedlings suffer from severe breakage and rot during transportation, reducing their survival rate. Traditional rice field azolla cultivation neglects nutrient supply and lacks measures to maintain its health. This results in insufficient nutrient accumulation before overwintering, leading to weakness, reddening, and decreased resistance, significantly reducing Azolla's cold tolerance. Summary of the Invention

[0004] In order to solve the above problems, a shed or greenhouse is used to preserve the Azolla seedlings, and a transparent plastic film is covered to increase the local environmental temperature of the Azolla growth, thereby avoiding the frost damage stress caused by low temperature to the Azolla. At the same time, a special fertilizer for Azolla overwintering is applied to allow Azolla to accumulate sufficient nutrients before overwintering, thereby effectively improving the cold resistance of Azolla and reducing the rot disease of Azolla. The present invention advocates preserving Azolla seedlings in nearby fields. After Azolla successfully overwintered, it is directly transferred to nearby fields for large-scale propagation, thereby avoiding the energy consumption and cost of transporting Azolla seedlings to other places and the problems of broken Azolla and rotting during transportation, and can effectively improve the survival rate of Azolla seedlings. Specifically comprising the following steps:

[0005] Step 1: half a month before the onset of winter, build a greenhouse and set up a seedling pool in the greenhouse with a water depth of ≥5cm.

[0006] Preferably, the half month before the onset of winter is the half month before the onset of climate temperature ≤-4°C.

[0007] Preferably, the water depth of the seedling pond is 5cm-20cm.

[0008] Step 2: Apply special fertilizer for Azolla overwintering and organic fertilizer to the seedling pond. After the special fertilizer for Azolla overwintering is applied, the P concentration in the water of the seedling pond is 3-10ppm, the K concentration is 10-20ppm, the Ca concentration is 10-20ppm, and the Mg concentration is 10-20ppm. The total nutrient content of the organic fertilizer is ≥4%, and the organic matter content is ≥30%.

[0009] Preferably, the amount of organic fertilizer applied is 300g / m 2 Most preferably, the organic fertilizer is obtained by fermenting livestock manure and vinegar residue in a mass ratio of 7:3. Most preferably, the livestock manure is cow manure or pig manure.

[0010] Step 3: Transfer the Azolla to the seedling pond, with the Azolla covering 50% to 90% of the water surface.

[0011] Step 4: Cover the seedling pond with a transparent plastic film and prop up the film with a support rod. Apply special fertilizer for Azolla overwintering once every 30 days. The application amount is the same as in step 2. When the thickness of Azolla is greater than 1 cm, remove one-third of the Azolla area.

[0012] The present invention has the following advantages:

[0013] (1) The present invention utilizes the greenhouse effect of a greenhouse or a greenhouse and covers it with a light-transmitting plastic film to increase the local environmental temperature for the growth of Azolla, thereby promoting the smooth wintering of Azolla seedlings and avoiding frost damage.

[0014] (2) The present invention applies azolla overwintering fertilizer, which allows the azolla to accumulate sufficient nutrients before overwintering, which can effectively improve the resistance of the azolla and reduce the rot disease of the azolla. Since the azolla grows slowly in the low temperature stage in winter, the nutrient concentration supplied to the azolla for growth should not be too high or too low. The International Rice Research Institute's standard azolla nutrient solution formula (IRRI Medium) has exceeded the slow growth requirements of the azolla in the low temperature stage in winter, and is prone to high salt stress symptoms, resulting in a decrease in the resistance of the azolla; while too low a nutrient supply or no fertilization will lead to insufficient nutrients for the azolla, making it difficult to continue growing through the long winter (November to March of the following year). The proposed winter fertilizer for Azolla reduces the amount of four macronutrients required for growth to match the plant's slow growth rate. Furthermore, a single commercial organic fertilizer replaces the trace elements (iron, manganese, boron, zinc, copper, molybdenum, and cobalt) provided by the seven chemicals in IRRI Medium (MnCl2·4H2O, Na2MoO4·2H2O, H3BO3, ZnSO4, CuSO4·5H2O, FeSO4·EDTA, and CoCl2·6H2O). Compared to the seven chemicals in IRRI Medium, the organic fertilizer is not only more cost-effective and easier to weigh, but also slowly releases other trace elements and nutrients, better meeting Azolla's growth needs and significantly improving its resistance to pythium.

[0015] (3) Under traditional rice field cultivation measures, areas without Azolla seedlings usually use Azolla seedlings transported from other places for propagation. The transportation process increases energy consumption and costs, and inevitably causes problems such as broken and rotten duckweed and low survival rate of Azolla seedlings. The present invention preserves Azolla seedlings by building a greenhouse or a greenhouse near the nearby field. After the Azolla successfully survives the winter, it is directly transferred to the nearby field for large-scale propagation, thereby avoiding the energy consumption and cost of transporting Azolla seedlings from other places and the problems of broken and rotten duckweed during transportation, and can effectively improve the survival rate of Azolla seedlings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0017] Figure 1 This is a traditional method of cultivating duckweed in open-air rice fields.

[0018] Figure 2 This is a comparison of duckweed cultivation measures in a greenhouse with and without covering it with translucent plastic film. The left picture shows covered with film, and the right picture shows uncovered with film.

[0019] Figure 3A comparison chart of the azolla cultivation measures in the greenhouse: applying organic fertilizer + special fertilizer for overwintering of azolla (left) and applying azolla nutrient solution formula (right). DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] Example 1

[0022] This embodiment provides a method for overwintering storage of Azolla seedlings in paddy fields, which specifically includes the following steps:

[0023] Step 1: Set up a greenhouse half a month before the arrival of climate temperature ≤-4℃, and set up a seedling pool in the greenhouse with a water depth of 10cm.

[0024] Step 2: Apply special fertilizer for overwintering of Azolla and organic fertilizer to the seedling pond. After the special fertilizer for overwintering of Azolla is applied, the concentration of P in the water of the seedling pond is 5ppm, the concentration of K is 15ppm, the concentration of Ca is 15ppm, and the concentration of Mg is 15ppm. The total nutrient content of the organic fertilizer is ≥4%, the organic matter content is ≥30%, and the application rate of the organic fertilizer is 300g / m 2 .

[0025] Step 3: Transfer the Azolla bodies to the seedling pond, with the Azolla bodies covering 70% of the water surface.

[0026] Step 4: Cover the seedling pool with a transparent plastic film and prop up the transparent plastic film with a support rod. Apply special fertilizer for Azolla overwintering once every 28 days. The application amount is the same as in step 2. When the thickness of Azolla is greater than 1 cm, remove one-third of the area of ​​Azolla.

[0027] Comparative Example 1

[0028] The difference from Example 1 is that this comparative example is to culture duckweed in an open air environment instead of in a greenhouse.

[0029] Comparative Example 2

[0030] The difference from Example 1 is that this comparative example is not covered with a transparent plastic film.

[0031] Comparative Example 3

[0032] The difference from Example 1 is that in this comparative example, no organic fertilizer + Azolla wintering fertilizer was applied, but a standard Azolla nutrient solution formula (IRRI Medium) was applied instead.

[0033] Test Example 1

[0034] After the duckweed raising was completed, the duckweed raising conditions of Example 1 and Comparative Examples 1-3 were compared. Figure 1-3 shown.

[0035] Depend on Figure 1 It can be seen that under the traditional rice field duckweed cultivation measures, there is a lack of measures to protect and strengthen duckweed in winter. The red duckweed is thin and red, has weak resistance, and its roots are easily attached to algae when exposed to light, and it is easy to die due to frost damage. Figure 2 It can be seen that the plastic film was not supported by support rods, which led to the collapse of the plastic film and the close contact with the red duckweed, causing rot problems. Figure 3 It can be seen that traditional rice field azolla cultivation practices do not include fertilization before wintering, lacking measures to maintain the azolla's condition. Insufficient nutrient accumulation in azolla seedlings can lead to weak, reddened plants, and weak resistance, making them susceptible to Pythium diseases. The present invention applies azolla-specific wintering fertilizer, allowing the azolla to accumulate sufficient nutrients before wintering, effectively improving its resistance and reducing its Pythium disease risk.

[0036] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for storing Azolla seedlings over the winter, characterized in that: The following steps are involved: Step 1: half a month before the onset of winter, build a greenhouse and set up a seedling pool in the greenhouse with a water depth of ≥5cm; Step 2, applying Azolla wintering fertilizer and organic fertilizer to the seedling pond, wherein the Azolla wintering fertilizer is applied to adjust the P concentration in the seedling pond water to 3-10 ppm, the K concentration to 10-20 ppm, the Ca concentration to 10-20 ppm, and the Mg concentration to 10-20 ppm, and the total nutrient content of the organic fertilizer is ≥4%, and the organic matter content is ≥30%; Step 3: Transfer the Azolla to the seedling pond, with the Azolla covering 50% to 90% of the water surface. Step 4: Cover the seedling pond with a transparent plastic film and prop up the film with a support rod. Apply special fertilizer for Azolla overwintering once every 30 days. The application amount is the same as in step 2. When the thickness of Azolla is greater than 1 cm, remove one-third of the Azolla area.

2. A method for overwintering storage of Azolla seedlings according to claim 1, characterized in that: The half month before the onset of winter in step 1 is the half month before the onset of climate temperature ≤-4°C.

3. A method for overwintering storage of Azolla seedlings according to claim 1, characterized in that: The water depth of the seedling pond described in step 1 is 5cm-20cm.

4. A method for overwintering storage of Azolla seedlings in rice fields according to claim 1, characterized in that: The amount of organic fertilizer applied in step 2 is 300g / m 2 .

5. A method for storing Azolla seedlings over the winter according to claim 1, characterized in that: The organic fertilizer in step 2 is prepared by fermenting livestock manure and vinegar residue in a mass ratio of 7:

3.

6. A method for storing Azolla seedlings over the winter according to claim 5, characterized in that: The livestock excrement is cow dung or pig dung.

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