Rapid propagation method for aquatic green manure azolla

Abstract

The invention relates to the technical field of azolla cultivation, in particular to a rapid propagation method for aquatic green manure azolla, and provides a special fertilizer for rapid propagation of azolla through water culture experiment exploration, namely the optimal nutrient supply amount and the optimal nutrient matching proportion of phosphorus, potassium, calcium and magnesium nutrient elements. And a low amount of organic fertilizer is applied, so that the azolla seedlings can be successfully subjected to'strong azolla ', namely, azolla individuals are robust, fat, bright green and strong in resistance. Thirdly, by establishing a small field parcel, putting azolla seedlings into the small field parcel and conducting small-scale centralized water and fertilizer management, water and fertilizer can be saved, the appropriate azolla population density, thickness and field surface water level are controlled, the biological nitrogen fixation efficiency of azolla can be greatly improved, and therefore rapid growth and successful propagation of azolla are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of Azolla breeding, and particularly relates to a method for rapidly breeding water green manure Azolla. BACKGROUND

[0002] Azolla has a very high biological nitrogen fixation capacity and is a high-quality water green manure. Rice farmers have introduced Azolla into rice fields more than 2,000 years ago, and used the biological nitrogen fixation of Azolla to provide additional nitrogen for rice, thereby increasing rice yield. Whether the Azolla seedlings can rapidly grow and cover the entire field after being put into the rice field is the first step of the Azolla breeding technology in the rice field. When the Azolla seedlings grow slowly, the Azolla population cannot rapidly cover the entire field (the coverage is less than 100%), and part of the sunlight penetrates into the water body, and water mites and algae begin to breed in the water body, attach to and entangle the Azolla roots, inhibit the growth of Azolla, and the young roots of Azolla are easily damaged by light, which may cause the death of Azolla and the failure of growth.

[0003] Azolla is a water floating plant, and mainly absorbs nutrients from the water body. Under the most suitable nutrient supply and growth environment, the biomass of Azolla can double every 2 days. When the nutrients in the water body are insufficient or unbalanced, the growth rate and resistance of Azolla decrease rapidly.

[0004] Phosphorus, potassium, calcium and magnesium are four kinds of macronutrients required for the growth of Azolla, and the insufficient supply or excessive supply of any one of the nutrient elements will cause the slow growth of Azolla. Under the traditional Azolla breeding technology in the rice field, only phosphorus and potassium fertilizers are applied to the Azolla seedlings put into the rice field, or no fertilizer is applied, and the demand of Azolla for calcium and magnesium and the nutrient allocation ratio of phosphorus, potassium, calcium and magnesium are ignored, which causes the low biological nitrogen fixation efficiency of Azolla, slow growth and failure of growth in high-temperature and strong-light weather, and makes it difficult for the Azolla in the rice field to play its role as a green manure. SUMMARY

[0005] Based on the above problems, the present application provides a method for rapidly breeding water green manure Azolla. The present application explores and proposes a special fertilizer for rapidly breeding Azolla through water culture experiments, i.e., the optimal nutrient supply amount and the most suitable nutrient matching ratio of phosphorus, potassium, calcium and magnesium. The present application can successfully achieve the "strong Azolla" of the Azolla seedlings by using the special fertilizer for rapidly breeding Azolla and applying a low amount of organic fertilizer, i.e., the Azolla individuals are healthy, large, fresh green and resistant. Then, the Azolla seedlings are put into a small field plot, and small-scale concentrated water and fertilizer management is carried out, so as to achieve water and fertilizer saving, control the appropriate density, thickness and water level of the Azolla population, and greatly improve the biological nitrogen fixation efficiency of Azolla, thereby achieving the rapid growth and successful breeding of Azolla. The method comprises the following steps:

[0006] Step one, establish a salvinia seedling pool near the rice field, and make the salvinia in the salvinia seedling pool strong, apply the special fertilizer for rapid propagation, and apply the organic fertilizer (the organic matter content is 30%, and the total nutrient content is 4%) to provide trace nutrients for the growth of the salvinia, so that the salvinia put into the rice field is fresh green, strong and fat, and the red and weak small individual is avoided, when the salvinia covers the whole water surface and the thickness reaches 0.5cm-1cm, the salvinia is in the exponential growth period, and the salvinia individual is the strongest and the propagation speed is the fastest.

[0007] Preferably, the application amount of the organic fertilizer is 200-400g / m 2 .

[0008] Step two, after ploughing the field, the soil is taken near the water inlet to establish a dike and enclose a small field, the dike is 15cm high, the water depth in the field is maintained at 5-10cm, the salvinia in the seedling pool is put into the small field, the salvinia covers 20%-40% of the water surface of the small field, and the special fertilizer for rapid propagation of salvinia is applied, and the water level of the small field is managed every two days to ensure that the water depth in the small field is 5-10cm.

[0009] Preferably, the area specification of the small field is 10m x 20m.

[0010] Step three, on the seventh day after fertilization, the salvinia can grow on the water surface of the small field, at this time, the thickness of the salvinia population is thin, about 0.5cm, and the special fertilizer for rapid propagation of salvinia needs to be applied again, and after one week, the salvinia population can reach the ideal thickness of 1cm.

[0011] Step four, when the thickness of the salvinia population reaches 1cm, the salvinia individual is in the most robust and fastest propagation stage, and the salvinia in the small field needs to be divided and put into the rice field outside the small field, and the special fertilizer for rapid propagation of salvinia is applied to the salvinia in the rice field, so that the salvinia can be massively propagated.

[0012] Preferably, when the special fertilizer for rapid propagation of salvinia is applied, the water reaches 16-32ppm P, 20-40ppm K, 20-40ppm Ca and 20-40ppm Mg. Most preferably, when the special fertilizer for rapid propagation of salvinia is applied, the water reaches 32ppm P, 40ppm K, 20ppm Ca and 20ppm Mg.

[0013] The application has the following advantages:

[0014] (1) The salvinia treated by the strong salvinia measure is selected for putting, the strong salvinia has strong disease resistance and stress resistance, and is extremely beneficial to the rapid propagation of the salvinia.

[0015] (2) The present application establishes a small field block at the irrigation inlet of a large field block, and the red algae treated by the strong algae measure is first put into the small field block for small-scale concentrated water and fertilizer management, so that water and fertilizer can be saved.

[0016] (3) The red algae likes to grow in groups, and the red algae is bred in the small field block. The red algae can grow full in the small field block in a short time, which not only inhibits the growth of algae and waterweed, but also provides shading conditions for the root system. When the red algae population grows to the best thickness, the red algae grows most vigorously and reproduces fastest. At this time, the red algae in 4 / 5 area of the small field block is transferred to the large field block, and the red algae rapid breeding special fertilizer is applied, so that large-scale rapid expansion can be carried out.

[0017] (4) Under the traditional rice field algae breeding technology system, no fertilizer is applied to the red algae or only phosphorus and potassium fertilizer is applied to the red algae, and calcium and magnesium fertilizer is ignored. The low concentration of calcium and magnesium in the field water cannot meet the needs of the rapid growth of the red algae, resulting in weak growth of the red algae, which is easy to die under stress such as high temperature and strong light. The present application explores and optimizes the best supply amount and the most suitable matching ratio of phosphorus, potassium, calcium and magnesium required for the rapid growth of the red algae, so that the rapid breeding of the red algae can be realized. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and those skilled in the art can obtain other drawings according to the provided drawings without creative labor.

[0019] Figure 1 The influence of different concentrations of phosphorus, potassium, calcium and magnesium on the growth rate of red algae under greenhouse water culture conditions.

[0020] Figure 2 The red algae growth condition comparison chart of traditional rice field algae breeding and the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described in detail below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0022] Test Example 1

[0023] In this test example, different concentration levels of phosphorus, potassium, calcium and magnesium and their combinations required by the red algae are set through greenhouse water culture experiment, and the initial amount of fresh algae is 200g / m 2, the nutrient solution was replaced once a week (all treatments had the same concentration of microelements: 2 ppm Fe, 0.5 ppm Mn, 0.2 ppm B, 0.1 ppm Mo, 0.01 ppm Zn, 0.01 ppm Cu, 0.01 ppm Co, but the concentrations of macroelements P, K, Ca and Mg were different, see the description of each treatment below), and the fresh weight of duckweed was maintained at the initial amount. The greenhouse culture conditions were 16 h / 8 h of day and night, 26℃ / 21℃, and 450 μmol quantam of white light intensity. -2 s -1 , RH 40%. Three concentration gradients of P, K, Ca and Mg were set, namely high concentration (32 ppm P, 40 ppm K, 40 ppm Ca and 40 ppm Mg), medium concentration (1 / 2 of the high concentration) and low concentration (1 / 4 of the high concentration); the control group: simulated no fertilization of field water phosphorus, potassium, calcium and magnesium concentration, 0.1 ppm P, 0.1 ppm K, 0.1 ppm Ca, 0.1 ppm Mg, the results are shown in Figure 1 .

[0024] As can be seen from Figure 1 , the growth rate of duckweed in the control treatment without applying phosphorus, potassium, calcium and magnesium fertilizer is the lowest, while the simultaneous application of phosphorus, potassium, calcium and magnesium fertilizer can greatly improve the growth rate of duckweed. The growth rate of duckweed under low concentration of phosphorus, potassium, calcium and magnesium is 1586% higher than that without applying phosphorus, potassium, calcium and magnesium (p<0.05), the growth rate of duckweed under medium concentration of phosphorus, potassium, calcium and magnesium is 102% higher than that under low concentration of phosphorus, potassium, calcium and magnesium (p<0.05), and the growth rate of duckweed under high concentration of phosphorus, potassium, calcium and magnesium is 6% higher than that under medium concentration of phosphorus, potassium, calcium and magnesium (p<0.05). In order to explore the minimum amount of calcium and magnesium and avoid the problem of soil salinization caused by excessive application of calcium and magnesium, the calcium and magnesium regulation treatment was set, that is, maintaining high concentration of phosphorus and potassium, and reducing the application of calcium and magnesium. Compared with high concentration of calcium and magnesium, when the concentration of calcium and magnesium is reduced to medium concentration, the growth rate of duckweed slightly decreases (p>0.05), but the difference is not significant. When the concentration of calcium and magnesium is reduced to low concentration, the growth rate of duckweed is significantly lower than that of high concentration (p<0.05). Similar rules are shown when calcium or magnesium is reduced alone, that is, when the concentration of calcium or magnesium is reduced from high to medium, the growth rate of duckweed slightly decreases (p>0.05), and when the concentration of calcium or magnesium is reduced to low, the growth rate of duckweed is significantly lower than that of high concentration (p<0.05). Based on the above results, the patent proposes a special fertilizer for rapid breeding of duckweed. According to the area of the field and the depth of the water level, the application of the fertilizer can make the P, K, Ca and Mg concentrations of the field water reach 32 ppm P, 40 ppm K, 20 ppm Ca and 20 ppm Mg, which is the optimal nutrient ratio for rapid breeding of duckweed in rice fields.

[0025] Example 1

[0026] Step one, establish Azolla seedling pool near rice field, strengthen Azolla in Azolla seedling pool, apply fast multiplication special fertilizer (32ppm P, 40ppm K, 20ppm Ca, 20ppm Mg) and organic fertilizer (300g / m 2 ), when Azolla covers the whole water surface and the thickness reaches 0.7cm, prepare to put into rice field.

[0027] Step two, after leveling rice field, establish small field (10m x 20m) near water inlet, maintain 7cm water depth in field, put Azolla in seedling pool into field, ensure Azolla covers 30% of field water surface, and apply Azolla fast multiplication special fertilizer (32ppm P, 40ppm K, 20ppm Ca, 20ppm Mg), manage field water every two days to ensure 7cm water depth.

[0028] Step three, on the 7th day after fertilization, Azolla covers the water surface of small field, at this time the thickness of Azolla population is 0.5cm, apply Azolla fast multiplication special fertilizer (32ppm P, 40ppm K, 20ppm Ca, 20ppm Mg) again, after one week, the thickness of Azolla population reaches 1cm.

[0029] Step four, take 4 / 5 area of Azolla in small field to rice field, and apply Azolla fast multiplication special fertilizer (32ppm P, 40ppm K, 20ppm Ca, 20ppm Mg) to Azolla in rice field, Azolla can be massively multiplied, the effect is shown in Figure 2 .

[0030] The above description of disclosed embodiments enables those skilled in the art to carry out or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application. Accordingly, the present application is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for rapid propagation of aquatic green manure duckweed, characterized in that, Includes the following steps: Step 1: Establish a duckweed seedling pond near the paddy field. Apply special fertilizer for rapid propagation of duckweed and organic fertilizer to the seedling pond. When the duckweed covers the entire water surface and reaches a thickness of 0.5cm-1cm, prepare to release the duckweed into the paddy field. Step 2: After leveling the paddy field, use local soil to build dikes and enclose small plots. Maintain a water depth of 5-10cm in the small plots. Place the duckweed from the seedling pond into the small plots, ensuring that the duckweed covers 20%-40% of the water surface. Apply a special fertilizer for rapid propagation of duckweed to the plots and maintain a water depth of 5-10cm in the small plots. Step 3: When the red duckweed reaches a thickness of 0.5cm, apply red duckweed rapid propagation fertilizer to the small plot once more; Step 4: When the thickness of the duckweed population reaches 1cm, scoop out 4 / 5 of the duckweed in the small field and transfer it to the paddy field outside the field. Apply a special fertilizer for rapid propagation of duckweed to the duckweed in the paddy field. When applying the special fertilizer for rapid propagation of Aucklandia lappa, ensure that the water concentrations reach 16-32 ppm P, 20-40 ppm K, 20-40 ppm Ca, and 20-40 ppm Mg.

2. The method for rapid propagation of aquatic green manure duckweed according to claim 1, characterized in that, The amount of organic fertilizer applied in step one is 200-400 g / m³. 2 .

3. The method for rapid propagation of aquatic green manure duckweed according to claim 1, characterized in that, The field area in step two is 10m × 20m.

4. A method for rapid propagation of aquatic green manure duckweed according to any one of claims 1-3, characterized in that, When applying the special fertilizer for rapid propagation of Aucklandia lappa, ensure that the water concentrations reach 32 ppm P, 40 ppm K, 20 ppm Ca, and 20 ppm Mg.

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