Microalgae nutrient solution, fertilizer composition and sugar beet fertilizing method

Abstract

The invention provides a microalgae nutrient solution and application thereof, and belongs to the technical field of agriculture. The invention provides a microalgae nutrient solution. The microalgae nutrient solution comprises nitrogen-fixing blue-green algae and photosynthetic nutrient green algae, the content of algae single cells in the microalgae nutrient solution is greater than or equal to 1.0 * 10 < 6 >. The microalgae nutrient solution provided by the invention, as a microalgae fertilizer, can significantly improve the activities of urease, sucrase and catalase in soil and reduce the activity of polyphenol oxidase in the soil; the content of alkali-hydrolyzable nitrogen in soil is increased, and the nitrogen fertilizer absorption amount of beet is improved; the richness of soil microbial communities can be increased, and the number of actinomycetes and proteobacteria is increased; growth and development of the beet can be remarkably promoted, the plant height, fresh weight, leaf number, chlorophyll content and net photosynthetic rate of the beet can be improved, accumulation of dry matter of beet tuberous roots can be promoted, timely transfer of beet growth centers can be regulated, and then the yield and sugar yield of the beet can be increased.

Description

Technical Field

[0001] The invention belongs to the technical field of agriculture, and in particular relates to a microalgae nutrient solution, a fertilizer composition and a beet fertilization method. Background Art

[0002] Sugar beet (Beta vulgaris L.) is one of the important sugar crops, which has the characteristics of cold resistance, drought resistance, salt and alkali resistance, wide adaptability, high economic value, etc. At present, the mechanization of sugar beet planting has been gradually improved, and the scale of sugar beet planting has also changed greatly.

[0003] While the scale of sugar beet cultivation has been steadily increasing, achieving cost savings, efficiency improvement, high yield and high sugar content in sugar beet cultivation has increasingly become an important goal for the development of the sugar beet industry. In recent years, with the increase in sugar beet planting area, some growers have relied too much on chemical fertilizers, especially excessive use of nitrogen fertilizers, in pursuit of higher yields. This has led to an unbalanced nutrient supply for sugar beets and low fertilizer utilization, which ultimately affected the yield and quality improvement of sugar beets. How to solve the many problems caused by excessive use of chemical fertilizers in sugar beet production, including increasing planting costs, reducing sugar beet quality, weakening soil fertility, and causing non-point source pollution, is one of the main problems facing sugar beet cultivation. Therefore, it has become an important issue that needs to be urgently addressed to reasonably regulate the amount of chemical fertilizers applied in sugar beet cultivation and improve fertilizer utilization. Summary of the invention

[0004] In view of the defects in the prior art, the object of the present invention is to provide a microalgae nutrient solution, which can be used as a microalgae fertilizer to increase the yield of sugar beets while reducing the application of chemical fertilizers.

[0005] The objective of the present invention is achieved through the following technical solutions:

[0006] The present invention provides a microalgae nutrient solution, which comprises, by percentage of single algae cells, 30% to 50% of nitrogen-fixing cyanobacteria No. 1, 10% to 20% of nitrogen-fixing cyanobacteria No. 2, and 40% to 50% of photosynthetic green algae; the single algae cell content in the microalgae nutrient solution is ≥1.0×10 6 Pieces / mL;

[0007] The nitrogen-fixing cyanobacteria No. 1 includes Anabaena; and the nitrogen-fixing cyanobacteria No. 2 includes Monochamus.

[0008] Preferably, the microalgae nutrient solution, calculated as a percentage of algae single cells, comprises:

[0009] Nitrogen-fixing cyanobacteria No. 1 40%, nitrogen-fixing cyanobacteria No. 2 20% and photosynthetic green algae 40%.

[0010] The present invention provides a fertilizer composition, comprising the microalgae nutrient solution described in the above technical solution and an inorganic fertilizer.

[0011] The present invention provides the use of the microalgae nutrient solution described in the above technical solution or the fertilizer composition described in the above technical solution in promoting sugar beet growth and / or improving soil physical and chemical properties.

[0012] Preferably, the method for promoting the growth of beets includes any one or more of the following (1) to (9):

[0013] (1) Increase sugar beet yield; (2) Increase sugar beet yield; (3) Increase sugar beet plant height; (4) Increase the number of sugar beet leaves; (5) Increase the fresh weight and / or dry weight of sugar beets; (6) Improve the root-to-shoot ratio of sugar beets; (7) Increase the photosynthetic rate of sugar beets; (8) Increase the chlorophyll content of leaves; (9) Enhance the nitrogen absorption capacity of sugar beets.

[0014] Preferably, increasing the fresh weight and / or dry weight of sugar beets includes any one or more of increasing the fresh weight and / or dry weight of sugar beets above ground, increasing the fresh weight and / or dry weight of sugar beets underground, increasing the dry matter accumulation of sugar beet leaves and increasing the dry matter accumulation of sugar beet roots.

[0015] Preferably, the improvement of soil physical and chemical properties includes any one or more of the following (a) to (d):

[0016] (a) Improve soil pH; (b) Increase soil alkaline nitrogen; (c) Improve soil enzyme activity; (d) Improve soil microbial community.

[0017] Preferably, the improvement of soil enzyme activity includes any one or more of increasing urease activity in the soil, increasing sucrase activity in the soil, increasing catalase activity in the soil and reducing soil polyphenol oxidase activity; the improvement of soil microbial community includes any one or more of increasing the richness of soil microbial community, increasing the number of actinomycetes, increasing the number of proteobacteria, reducing the relative abundance of acidobacilli and increasing the number of sphingomonas.

[0018] The invention provides a beet fertilization method, comprising:

[0019] Applying basal fertilizer when planting beets; the basal fertilizer includes nitrogen fertilizer, phosphorus fertilizer and potash fertilizer;

[0020] The microalgae nutrient solution described in the above technical solution was applied to 15 true leaves of beet seedlings.

[0021] Preferably, the application rate of the microalgae nutrient solution is 6 to 12 L / hm 2 ; The application rate of the nitrogen fertilizer is 94.5~135kg / hm 2 .

[0022] Beneficial effects of the present invention: The present invention provides a microalgae nutrient solution, which comprises, by percentage of single algae cells, 30% to 50% of nitrogen-fixing cyanobacteria No. 1, 10% to 20% of nitrogen-fixing cyanobacteria No. 2, and 40% to 50% of photosynthetic green algae; the single algae cell content in the microalgae nutrient solution is ≥ 1.0×10 6 / mL; the nitrogen-fixing cyanobacteria No. 1 includes Anabaena; the nitrogen-fixing cyanobacteria No. 2 includes Monochamus. The photosynthetic green algae and nitrogen-fixing cyanobacteria in the microalgae nutrient solution provided by the present invention carry out oxygen-producing photosynthesis and nitrogen fixation with heteromorphic cells as carriers, which helps to enrich the diversity of soil flora structure, maintain the appropriate pH of the soil, and optimize the physical and chemical properties of the soil. The nitrogen-fixing cyanobacteria can effectively utilize the nutrients in the soil and stimulate photosynthetic bacteria to adjust and improve the pH. At the same time, the algae single cells in the microalgae nutrient solution can exist in the form of a covering layer around the root hairs, forming an external symbiotic relationship with the surface of the beet root hairs, and the nutrients produced by the microalgae during the growth process can be directly absorbed and utilized by the beet root system, which is beneficial to promote the growth and development of beets. The microalgae nutrient solution provided by the present invention can be used as a microalgae fertilizer to significantly increase the activities of urease, sucrase, and catalase in the soil, and reduce the activity of soil polyphenol oxidase; increase the content of alkaline nitrogen in the soil, and increase the absorption of nitrogen fertilizer by beets; increase the richness of soil microbial communities, and increase the number of actinomycetes and proteobacteria. The improvement of the rational properties of the soil by the microalgae nutrient solution of the present invention is beneficial to promoting the absorption and utilization of nutrients by beets. In the present invention, the microalgae nutrient solution can significantly promote the growth and development of beets, increase the height and fresh weight of beets, increase the number of leaves, increase the chlorophyll content, improve the net photosynthetic rate of beets, promote the accumulation of dry matter of beet tubers, and regulate the timely transfer of the growth center of beets, thereby helping to increase the yield and sugar yield of beets. In the present invention, when the microalgae nutrient solution is combined with a 10% nitrogen-reducing inorganic fertilizer, relative to the microalgae nutrient solution combined with a non-nitrogen-reducing inorganic fertilizer, the soil alkaline nitrogen, urease, sucrase, and catalase activities can be effectively increased, the soil polyphenol oxidase activity can be reduced, the soil alkaline nitrogen content can be increased, the net photosynthetic rate of beets can be enhanced, and the accumulation of beet substances can be promoted. Therefore, the microalgae nutrient solution provided by the present invention can achieve the purpose of reducing nitrogen and increasing the yield of beets as a fertilizer for beets. In summary, the microalgae nutrient solution provided by the present invention can improve the physical and chemical properties of the soil while promoting the growth of beets as a microalgae fertilizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0024] Figure 1The figure is the effect of different fertilizer compositions on urease activity in sugar beet soil;

[0025] Figure 2 The figure is the effect of different fertilizer compositions on the sucrase activity in sugar beet soil;

[0026] Figure 3 is a graph showing the effect of different fertilizer compositions on soil catalase activity;

[0027] Figure 4 is a graph showing the effect of different fertilizer compositions on soil polyphenol oxidase activity;

[0028] Figure 5 The figure shows the effect of different fertilizer combinations on soil community composition;

[0029] Figure 6 Circos diagram of soil sample communities after application of different fertilizer combinations;

[0030] Figure 7 The figure shows the effect of different fertilizer combinations on sugar beet plant height;

[0031] Figure 8 The figure is the effect of different fertilizer compositions on the number of sugar beet leaves;

[0032] Fig. 9 The figure shows the effect of different fertilizer compositions on the fresh weight of sugar beets;

[0033] Fig.10 The figure is the effect of different fertilizer compositions on the dry matter accumulation of sugar beet leaves;

[0034] Fig.11 The figure is the effect of different fertilizer compositions on the dry matter accumulation of sugar beet roots;

[0035] Fig.12 The figure shows the effect of different fertilizer compositions on the root-to-crown ratio of sugar beet;

[0036] Fig.13 The figure is the effect of different fertilizer compositions on the net leaf photosynthetic rate of sugar beet;

[0037] Fig.14 The effect of different fertilizer compositions on the net leaf SPAD value of sugar beet;

[0038] Fig.15 Microscopic structure of beet root hairs for the application of microalgae fertilizer;

[0039] Fig.16 This is a microscopic picture of the root hairs of beets without the application of microalgae fertilizer;

[0040] Fig.17 This is the correlation analysis chart between soil characteristic index and sugar beet yield and quality;

[0041] Fig.18 This is a correlation analysis chart between sugar beet physiological characteristics and sugar beet yield and quality. DETAILED DESCRIPTION

[0042] The present invention provides a microalgae nutrient solution, which comprises, by percentage of single algae cells, 30% to 50% of nitrogen-fixing cyanobacteria No. 1, 10% to 20% of nitrogen-fixing cyanobacteria No. 2, and 40% to 50% of photosynthetic green algae; the single algae cell content in the microalgae nutrient solution is ≥1.0×10 6 In the present invention, there is no order of precedence between nitrogen-fixing cyanobacteria No. 1 and nitrogen-fixing cyanobacteria No. 2, and they are only for the purpose of distinction.

[0043] The microalgae nutrient solution provided by the present invention includes 30% to 50% of nitrogen-fixing cyanobacteria No. 1, and may be 40%, based on the percentage of single algae cells. The nitrogen-fixing cyanobacteria No. 1 provided by the present invention includes Anabaena. The Anabaena can convert free nitrogen in the air into nitrogen-containing biological fertilizers, thereby promoting the growth of plants.

[0044] According to the percentage of single algae cells, the microalgae nutrient solution provided by the present invention includes 10% to 20% of nitrogen-fixing cyanobacteria No. 2, which can be 20%. The nitrogen-fixing cyanobacteria No. 2 provided by the present invention includes monophyll. The monophyll has efficient nitrogen fixation and decomposition functions, can fix molecular nitrogen in the atmosphere into bound nitrogen, and further synthesize protein to increase soil fertility; after the algae cells enter the soil, they can wrap the plant root system, and extend with the root system to provide sufficient nutrients for the root.

[0045] The microalgae nutrient solution provided by the present invention includes 40% to 50% of photosynthetic nutrient green algae, which can be 40%, based on the percentage of single algae cells. The photosynthetic nutrient green algae can improve soil organic matter while the amino acids and hormone substances contained in it can also play a positive role in promoting plant growth.

[0046] The microalgae nutrient solution provided by the present invention has a single cell content of ≥1.0×10 6 / mL, which can be 1.0×10 6 Pieces / mL.

[0047] In addition to promoting the growth of beets through self-metabolism, the algae single cells in the microalgae nutrient solution provided by the present invention can also exist in the form of a covering layer around the root hairs, forming an external symbiotic relationship with the surface of the beet root hairs, and the nutrients produced by the microalgae during the growth process can be directly absorbed and utilized by the beet root system, which is beneficial to promoting the growth and development of beets. In the present invention, the microalgae nutrient solution can significantly promote the growth and development of beets as a microalgae fertilizer, increase the plant height and fresh weight of beets, increase the number of leaves, increase the chlorophyll content, improve the net photosynthetic rate of beets, promote the accumulation of dry matter of beet tubers, regulate the timely transfer of beet growth centers, and thus increase the yield and sugar production of beets; the microalgae nutrient solution can significantly increase the activities of urease, sucrase, and catalase in the soil as a microalgae fertilizer, and reduce the activity of soil polyphenol oxidase; increase the alkaline nitrogen content in the soil, and increase the absorption of nitrogen fertilizer by beets; increase the richness of soil microbial communities, increase the number of actinomycetes and proteobacteria, etc., and thus promote the absorption and utilization of nutrients by beets. Furthermore, the microalgae nutrient solution provided by the present invention can be used together with inorganic fertilizers that reduce nitrogen, which is beneficial to better promote the growth of sugar beets and increase the yield of sugar beets, and also has a good effect on improving the physical and chemical properties of the soil. The microalgae nutrient solution provided by the present invention provides an effective way for the rational fertilization of sugar beets. In the present invention, when the microalgae nutrient solution is combined with inorganic fertilizers that reduce nitrogen by 10%, compared with the microalgae nutrient solution combined with inorganic fertilizers that do not reduce nitrogen, it can effectively increase the soil alkaline nitrogen, urease, sucrase, and catalase activities, reduce the soil polyphenol oxidase activity, increase the soil alkaline nitrogen content, enhance the net photosynthetic rate of sugar beets, and promote the accumulation of sugar beet substances. Therefore, the microalgae nutrient solution provided by the present invention can achieve the purpose of reducing nitrogen and increasing sugar beet production as a fertilizer for sugar beets.

[0048] The present invention provides a fertilizer composition, comprising the microalgae nutrient solution and inorganic fertilizer described in the above technical solution. In the present invention, the inorganic fertilizer may include any one or more of nitrogen fertilizer, phosphorus fertilizer and potassium fertilizer. The microalgae nutrient solution in the fertilizer composition provided by the present invention may be applied in a different manner from the inorganic fertilizer, or may be applied in the same manner. In the present invention, the application method of the microalgae nutrient solution may be drip irrigation; the application method of the inorganic fertilizer may be a one-time application as a base fertilizer, or a one-time application or application in batches as a topdressing. As an optional embodiment of the present invention, the microalgae nutrient solution may be applied in the form of drip irrigation, and the application amount of the microalgae nutrient solution may be 6 to 12 L / hm 2 , can also be 6, 7, 8, 9, 10, 11 or 12 L / hm 2 As an optional embodiment of the present invention, the inorganic fertilizer includes nitrogen fertilizer, phosphate fertilizer and potash fertilizer. The nitrogen fertilizer is expressed as N, the phosphate fertilizer is expressed as P 2 O 5 The potassium fertilizer is K2 O, the mass ratio of the nitrogen fertilizer, the phosphorus fertilizer and the potassium fertilizer can be (94.5-135):150:150, or any one or more of 94.5:150:150, 108:150:150, 121.5:150:150 or 135:150:150. In the present invention, if the fertilizer composition is used for beets, the microalgae nutrient solution in the fertilizer composition can be 6-12 L / hm 2 , can also be 6, 7, 8, 9, 10, 11 or 12 L / hm 2 ; Nitrogen fertilizer is expressed as N, and phosphorus fertilizer is expressed as P 2 O 5 Potassium fertilizer is K 2 O, the nitrogen fertilizer in the inorganic fertilizer can be 94.5-135kg / hm 2 , can also be 94.5, 108, 121.5 or 135 kg / hm 2 ; Phosphate fertilizer in the inorganic fertilizer can be 150kg / hm 2 ; The potassium fertilizer in the inorganic fertilizer can be 150kg / hm 2 In the present invention, when the fertilizer composition is used for beets, the microalgae nutrient solution is preferably applied in the form of drip irrigation; the application is preferably applied when the beets have 15 true leaves in the seedling stage. The inorganic fertilizer is preferably applied in the form of basal fertilizer.

[0049] The fertilizer composition provided by the present invention can promote the growth of sugar beets and improve the physical and chemical properties of soil. The microalgae nutrient solution in the fertilizer composition provided by the present invention is used in combination with inorganic fertilizers, which can significantly promote the growth of sugar beets while reducing the nitrogen fertilizer in the inorganic fertilizers to a certain extent, and can significantly increase the yield of sugar beets while also improving the physical and chemical properties of soil.

[0050] The present invention provides the use of the microalgae nutrient solution described in the above technical solution or the fertilizer composition described in the above technical solution in promoting sugar beet growth and / or improving soil physical and chemical properties.

[0051] In the present invention, the promotion of sugar beet growth includes any one or more of the following (1) to (9): (1) increasing sugar beet yield; (2) increasing sugar beet sugar yield; (3) increasing sugar beet plant height; (4) increasing the number of sugar beet leaves; (5) increasing the fresh weight and / or dry weight of sugar beets; (6) improving the root-to-crown ratio of sugar beets; (7) increasing the photosynthetic rate of sugar beets; (8) increasing the chlorophyll content of leaves; and (9) enhancing the nitrogen absorption capacity of sugar beets.

[0052] In the present invention, the increase in the fresh weight and / or dry weight of sugar beets includes any one or more of increasing the fresh weight and / or dry weight of sugar beets above ground, increasing the fresh weight and / or dry weight of sugar beets underground, increasing the dry matter accumulation of sugar beet leaves and increasing the dry matter accumulation of sugar beet roots.

[0053] In the present invention, the improvement of soil physical and chemical properties includes any one or more of the following (a) to (d): (a) improving soil pH; (b) increasing soil alkaline nitrogen; (c) improving soil enzyme activity; (d) improving soil microbial community. In the present invention, the improvement of soil enzyme activity includes any one or more of increasing soil urease activity, increasing soil sucrase activity, increasing soil catalase activity and reducing soil polyphenol oxidase activity; the improvement of soil microbial community includes any one or more of increasing the richness of soil microbial community, increasing the number of actinomycetes, increasing the number of proteobacteria, reducing the relative abundance of acidobacteria and increasing the number of sphingomonas.

[0054] The invention provides a beet fertilization method, comprising:

[0055] Applying basal fertilizer when planting beets; the basal fertilizer includes nitrogen fertilizer, phosphorus fertilizer and potash fertilizer;

[0056] The microalgae nutrient solution described in the above technical solution is applied to 15 true leaves of beet seedlings.

[0057] In the present invention, the application amount of the microalgae nutrient solution is 6 to 12 L / hm 2 As an optional embodiment of the present invention, the application rate of the microalgae nutrient solution can be 6, 7, 8, 9, 10, 11 or 12 L / hm 2 In the present invention, nitrogen fertilizer is expressed as N, and phosphate fertilizer is expressed as P. 2 O 5 Potassium fertilizer is K 2 O, the nitrogen fertilizer in the inorganic fertilizer can be 94.5-135kg / hm 2 , can also be 94.5, 108, 121.5 or 135 kg / hm 2 ; Phosphate fertilizer in the inorganic fertilizer can be 150kg / hm 2 ; The potassium fertilizer in the inorganic fertilizer can be 150kg / hm 2 In the present invention, the microalgae nutrient solution is preferably applied in the form of drip irrigation; the application is preferably applied when the beet seedling has 15 true leaves. In the present invention, the microalgae nutrient solution is preferably diluted 100 times for application. In the present invention, the inorganic fertilizer is preferably applied in the form of basal fertilizer.

[0058] In order to further illustrate the present invention, the technical solution provided by the present invention is described in detail below in conjunction with the accompanying drawings and embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0059] Example 1

[0060] A microalgae nutrient solution, based on the percentage of single algae cells, is composed of: 40% of nitrogen-fixing cyanobacteria No. 1, 20% of nitrogen-fixing cyanobacteria No. 2, and 40% of photosynthetic green algae, wherein the nitrogen-fixing cyanobacteria No. 1 is specifically Anabaena; the nitrogen-fixing cyanobacteria No. 2 is specifically Monochamus. The single algae cell content in the microalgae nutrient solution is 1.0×10 6 Pieces / mL.

[0061] Example 2

[0062] A microalgae nutrient solution, calculated by the percentage of single algae cells, is composed of: 40% of nitrogen-fixing cyanobacteria No. 1, 10% of nitrogen-fixing cyanobacteria No. 2, and 50% of photosynthetic green algae, wherein the nitrogen-fixing cyanobacteria No. 1 is specifically Anabaena; the nitrogen-fixing cyanobacteria No. 2 is specifically Monochamus. The single algae cell content in the microalgae nutrient solution is 1.0×10 6 Pieces / mL.

[0063] Example 3

[0064] A fertilizer composition, comprising: 6 L of the microalgae nutrient solution of Example 1, 135 kg of nitrogen fertilizer (N), and 135 kg of phosphate fertilizer (P). 2 O 5 150kg and potassium fertilizer K 2 O total 150kg.

[0065] Example 4

[0066] A fertilizer composition, comprising: 9 L of the microalgae nutrient solution of Example 1, 135 kg of nitrogen fertilizer (N), and 135 kg of phosphate fertilizer (P). 2 O 5 150kg and potassium fertilizer K 2 O total 150kg.

[0067] Example 5

[0068] A fertilizer composition, comprising: 12 L of the microalgae nutrient solution of Example 1, 135 kg of nitrogen fertilizer (N), and 135 kg of phosphate fertilizer (P). 2 O 5 150kg and potassium fertilizer K 2 O total 150kg.

[0069] Example 6

[0070] A fertilizer composition, comprising: 9 L of the microalgae nutrient solution of Example 1, 121.5 kg of nitrogen fertilizer (N), and 121.5 kg of phosphate fertilizer (P). 2 O 5 150kg and potassium fertilizer K 2 O total 150kg.

[0071] Example 7

[0072] A fertilizer composition, comprising:

[0073] 9 L of microalgae nutrient solution of Example 1, 108 kg of nitrogen fertilizer (N), and 108 kg of phosphate fertilizer (P) 2 O 5 150kg and potassium fertilizer K 2 O total 150kg.

[0074] Example 8

[0075] A fertilizer composition, comprising: 9 L of the microalgae nutrient solution of Example 1, 94.5 kg of nitrogen fertilizer (N), and 94.5 kg of phosphate fertilizer (P). 2 O 5 150kg and potassium fertilizer K 2 O total 150kg.

[0076] Application Example 1

[0077] Effects of the microalgae nutrient solution of Example 1 as a fertilizer composition obtained by combining microalgae fertilizer with chemical fertilizer on the growth of sugar beets and on the fertility of sugar beet soil.

[0078] 1. Overview of the test site

[0079] The experimental site is located at the Agricultural and Animal Husbandry Science Academy of Ulanqab, Inner Mongolia (40.9232°N, 113.1196°E), which has a temperate continental monsoon climate, mostly cold and dry, with more wind and less rain, and a large temperature difference between day and night. The average annual temperature is 4.5℃, the highest temperature is 39.7℃, and the lowest temperature is -34.4℃; the annual precipitation is 376.1mm, and most of it is concentrated in July and early August; the average annual frost-free period is 131d.

[0080] 2. Experimental Design

[0081] 1) Test materials

[0082] Beet variety: IM1162. Tested microalgae fertilizer: the microalgae nutrient solution of Example 1.

[0083] Fertilizers tested: urea (N 46%), diammonium phosphate (N 18%, P 2 0 5 46%), potassium sulfate (K 2 O 50%).

[0084] Main instruments: conductivity meter, pH meter, portable chlorophyll fluorescence meter (PAM-2500), portable photosynthetic measurement system (HI-6400), constant temperature incubator, autoclave, clean bench, and ELISA reader.

[0085] 2) Experimental design and treatment

[0086] This experiment adopted a randomized block design and set three concentration gradients of microalgae fertilizer (6, 9, 12 L / hm2) based on a certain amount of chemical fertilizer. 2), the nitrogen fertilizer was reduced by 10%, 20%, and 30% respectively when the concentration of microalgae fertilizer remained unchanged, and the control group without microalgae fertilizer was set as CK, and a blank control group without fertilizer was set at the same time. The specific treatment conditions are shown in Table 1.

[0087] Table 1 Application of microalgae fertilizer with chemical fertilizer

[0088]

[0089]

[0090] In May 2023, paper tube seedlings were used for mechanical transplanting and planting. Fertilizer was applied once in the form of basal fertilizer, and then artificial seedlings were supplemented. Each treatment was repeated 3 times, with a total of 24 plots, each plot was 6.5m long, 5m wide, and 32.5m in area. 2 , with 3m protection rows around, 50cm planting row spacing, and 20cm plant spacing. When the beet seedlings have 15 true leaves (about 35-40 days after transplanting), drip irrigate the corresponding plot with 100 times diluted microalgae nutrient solution. Irrigate 4 times during the growth period, and irrigate once every 30 days after transplanting, with an irrigation volume of 450m3 each time. 3 / hm 2 , other field management methods are consistent with conventional field production.

[0091] 3) Sample collection

[0092] Plant samples: Take samples once 5 days after the microalgae fertilizer is applied, once during the rapid growth period of leaves, once during the tuber and sugar growth period, once during the sugar accumulation period, and once before harvest, for a total of 5 samples. Five beets with uniform growth were selected from each plot.

[0093] Soil samples: Sampling was carried out 5 times at four growth stages of sugar beet, using soil drill to press into the sample, and the sampling depth was 30cm. The soil samples to be tested were sealed in plastic bags and stored in a 4℃ refrigerator, and brought back to the laboratory for soil index measurement. 20-30g of fresh soil was selected and passed through a 2mm (10 mesh) sieve to measure soil enzyme activity. The remaining part was naturally air-dried, impurities were picked out, and ground through 0.125mm (100 mesh) for soil nutrient determination.

[0094] 4) Index determination method

[0095] (1) Determination of sugar beet yield and quality

[0096] Yield: Remove the side rows of each plot, count the remaining beetroots, and convert them into per-acre yield. Sugar content: Use a polarimeter to measure. And calculate the sugar content and sugar yield according to the following formula:

[0097] Sugar content (%) = Brix × 0.85; Sugar yield (kg / hm 2) = output (kg / hm 2 )×sugar content (%).

[0098] (2) Determination of soil physical and chemical properties

[0099] Soil pH determination: Use air-dried soil that has passed through a 30-mesh sieve and mix it at a water-soil mass ratio of 2.5:1, and then use a pH meter to determine the soil pH value; Soil alkaline nitrogen: Soil alkaline nitrogen is determined using the alkaline diffusion method. Each soil sample was repeated 3 times and the average value was taken.

[0100] (3) Determination of soil enzyme activity

[0101] About 0.3 g of air-dried soil samples were taken from each treatment group, and 3 samples were taken from each treatment group. The activities of soil-related enzymes were measured using the following methods.

[0102] Soil sucrase activity: 3,5-dinitrosalicylic acid colorimetric method; soil urease activity: phenol-sodium hypochlorite colorimetric method; soil catalase and polyphenol oxidase activities: pyrogallol colorimetric method.

[0103] (4) Soil microbial determination

[0104] About 35 days after the beet seedlings were transplanted, rhizosphere soil was collected for rhizosphere microbial diversity interactive cloud sequencing analysis using the QIIME2 process (provided by Meiji Biotech) to analyze the diversity, composition, and differences of soil microbial communities.

[0105] (5) Determination of beet morphological indicators

[0106] Plant height: Measure the longest leaf height with a ruler. Number of leaves: Count the number of functional leaves.

[0107] Leaf area index: Use the punch weighing method (calculated based on fresh weight).

[0108] Fresh weight: Select five beets with uniform growth in each plot and weigh the above-ground and underground parts.

[0109] Dry weight: The obtained samples were inactivated at 105°C for 30 min, dried at 60°C to constant weight, the dry weight was determined, and the samples were crushed and sieved for storage in order to determine the nutrient content.

[0110] Root-to-shoot ratio: calculate the dry weight of tubers / dry weight of leaves.

[0111] (6) Determination of photosynthetic indexes of sugar beet

[0112] Chlorophyll content: Use a SPAD meter to measure the SPAD value of the tip of the fourth leaf. Randomly select 5 beets from each plot with uniform growth for measurement. Avoid leaf veins during each measurement, and measure 5 times to get the average value.

[0113] Photosynthesis parameters: The net photosynthetic rate, stomatal conductance, transpiration rate, and intercellular CO2 of the fourth leaf of sugar beet were measured from 9:00 to 11:00 on sunny days using the Li-6400 portable photosynthesis system. 2 The red and blue light source leaf chamber (LED) was used, and the LED light quantum was set to 1500 μmol CO 2 ·m -2 ·s -1 Each treatment was measured three times.

[0114] (7) Determination of nutrient content of sugar beet plants

[0115] Determination of nitrogen content: concentrated sulfuric acid-hydrogen peroxide digestion, Kjeldahl method.

[0116] 5) Results and analysis

[0117] (1) Effects of different fertilizer combinations on sugar beet root yield, sugar content and sugar yield.

[0118] The sugar beet yield, sugar content and sugar yield of the groups treated with different fertilizer compositions are shown in Table 2.

[0119] Table 2 Sugar beet yield, sugar content and sugar yield of different fertilizer composition treatment groups

[0120] deal with <![CDATA[Yield (kg / hm 2 )]]> Sugar content (%) <![CDATA[Sugar yield (kg / hm 2 )]]> NW1 66574.23±1003.98b 17.82±0.98ab 11863.52±487.03b NW2 67875.34±901.90ab 18.03±1.02a 12237.92±536.22ab NW3 68278.09±893.61ab 17.62±1.13b 12030.60±537.09ab N1W2 70480.86±759.28a 17.73±0.89b 12496.26±730.06a N2W2 69230.08±941.73a 17.96±0.90ab 12433.72±680.09a N3W2 66347.87±881.78b 17.52±1.05b 11624.15±665.45b CK 63624.25±876.32c 16.94±0.90c 10777.95±760.23c

[0121] Note: Different lowercase letters indicate significant differences (P<0.05), the same below.

[0122] In terms of beet yield, as shown in Table 2, the application of microalgae fertilizer on the basis of chemical fertilizer, with the increase of microalgae fertilizer application, the beet yield showed a trend of gradual increase, showing NW3>NW2>NW1>CK. Among them, the yield of NW3 treatment was the highest and significantly different from CK, with an increase of 7.3% compared with CK. This shows that the application of microalgae fertilizer combined with chemical fertilizer can promote the increase of beet yield to a certain extent. When the application of microalgae fertilizer is 9L / hm 2 Under the same conditions, the amount of nitrogen fertilizer was appropriately reduced. The results showed that with the reduction of nitrogen fertilizer, the beet yield showed a gradual downward trend, which was N1W2>N2W2>N3W2. However, the yield was significantly higher than that of CK, among which the yield of N1W2 (nitrogen reduction 10%) treatment was the highest, reaching 70480.86 kg / hm 2 , an increase of 10.8% compared with CK. This shows that appropriate nitrogen reduction combined with microalgae fertilizer can promote the increase of sugar beet yield to a certain extent.

[0123] In terms of sugar content of beets, the results in Table 2 show that when microalgae fertilizer is applied in combination with chemical fertilizer, the sugar content of beets first increases and then decreases with the increase in the amount of microalgae fertilizer applied, showing NW2>NW1>NW3>CK. Among them, the sugar content of NW2 treatment is the highest, reaching 18.03%, indicating that the appropriate application of microalgae fertilizer has a certain effect on increasing the sugar content of beet roots. At the same time, the results of reducing chemical fertilizer and applying microalgae fertilizer show that when the application amount of microalgae fertilizer is 9L / hm 2 Under the same conditions, its sugar content was still significantly higher than that of CK, showing N2W2>N1W2>N3W2, among which the sugar content of N2W2 (20% nitrogen reduction) treatment was the highest at 17.96%, indicating that appropriate nitrogen reduction combined with microalgae fertilizer can increase the sugar content of beetroot to a certain extent.

[0124] The results of comprehensive analysis of sugar beet production are shown in Table 2. When the application rate of microalgae fertilizer is 9L / hm 2 Its sugar production can reach the highest level, reaching 12237.92 kg / hm 2 , which was significantly higher than CK. 2 When nitrogen was reduced appropriately, the sugar yield was N1W2>N2W2>N3W2>CK, and the sugar yield of each nitrogen reduction treatment was still significantly higher than that of CK, among which N1W2 treatment had the highest sugar yield. This shows that the appropriate microalgae fertilizer combined with chemical fertilizer treatment has a certain effect on improving the yield and quality of sugar beets.

[0125] (2) Effects of different fertilizer combinations on the physical and chemical properties of sugar beet soil

[0126] a. The effects of different fertilizer compositions on the pH of sugar beet soil are shown in Table 3.

[0127] Table 3 Effect of different fertilizer compositions on sugar beet soil pH

[0128]

[0129] Soil pH is an important indicator of soil physical and chemical properties. The results in Table 3 show that after the application of microalgae fertilizer with chemical fertilizer, the soil pH value showed an overall increasing trend with the increase of microalgae fertilizer application during the seedling age of 60 to 120 days, and was significantly higher than CK, but there was no significant difference among the treatments. 2 Under the same conditions, the soil pH value after nitrogen reduction treatment showed a slight increase trend during the 40-120 days of seedling age with the reduction of nitrogen fertilizer, which was higher than CK and the difference was significant. In general, the application of chemical fertilizers and microalgae fertilizers can stabilize the soil pH value between 7.5 and 8.0, which is conducive to the normal growth and development of sugar beets and the reproduction of alkaline active microalgae.

[0130] During the growth and development of beets, the closer the soil pH is to neutral or slightly alkaline, the more conducive it is to the growth of beets. Microalgae fertilizers stimulate photosynthetic bacteria, which decompose organic matter in the soil and produce carbon sources. After a certain period of reproduction, they help stabilize the soil pH and avoid the problem of excessive soil acidification. The application of microalgae fertilizers can effectively regulate the acid-base balance of the soil, especially in the late growth period, it can maintain the soil pH between 7.5-8.0.

[0131] b. The effects of different fertilizer compositions on soil alkaline nitrogen content are shown in Table 4.

[0132] Table 4 Effect of different fertilizer compositions on soil alkaline nitrogen content (unit: mg / kg)

[0133]

[0134] From the results in Table 4, it can be seen that the application of different amounts of microalgae fertilizer and the treatment of reduced nitrogen and microalgae fertilizer can significantly increase the soil alkaline nitrogen content compared with CK. Among them, the treatment of chemical fertilizer combined with microalgae fertilizer showed an overall increasing trend in soil alkaline nitrogen content at each growth period with the increase of microalgae fertilizer application amount. Among them, the soil alkaline nitrogen content of NW2 treatment was the highest at 40d and 100-120d of seedling age, while the difference in soil alkaline nitrogen content between NW2 and NW3 was not significant at 60-120d. When microalgae fertilizer was applied and nitrogen was reduced, the soil alkaline nitrogen content showed a gradual downward trend with the reduction of nitrogen fertilizer, but the soil alkaline nitrogen content of each treatment was still higher than that of CK, especially the N1W2 treatment was significantly different from CK. The soil alkaline nitrogen content of this treatment in each growth period was increased by 18.4%, 13.8%, 16.35%, 14.22% and 10.87% respectively compared with CK. It shows that the appropriate application of chemical fertilizer combined with microalgae fertilizer has a promoting effect on the increase of soil alkaline nitrogen content.

[0135] The application of microalgae fertilizer can significantly increase the alkaline nitrogen content of sugar beet soil. The higher the application concentration, the more obvious the effect is, and it is reflected in the uninterrupted effect during the whole growth period. It is also found that after the dosage reaches a certain level, the effect is basically constant, which is manifested as an application amount of 9L / hm 2 and 12L / hm 2 There was no significant difference in the alkaline nitrogen content in the soil.

[0136] (3) Effects of different fertilizer combinations on sugar beet soil enzyme activity

[0137] a. Effects of different fertilizer compositions on urease activity in sugar beet soils are shown in Tables 5 and Figure 1 shown.

[0138] Table 5 Effects of different fertilizer combinations on urease activity in sugar beet soil (mg·g -1 ·d -1 )

[0139]

[0140] The activity of soil urease (S-UE) is positively correlated with soil N utilization efficiency. Figure 1 From the results in Table 5, it can be seen that after the application of microalgae fertilizer with chemical fertilizer, the soil urease activity showed an increasing trend with the increase of microalgae fertilizer application during the seedling age of 60-100 days, showing NW3>NW2>NW1, and NW2 and NW3 were significantly higher than CK. Among them, the soil urease activity of NW3 treatment reached the maximum value at 60-120 days, increasing by 9%, 15%, 14.6% and 7.1% respectively compared with CK. This shows that the application of microalgae fertilizer can improve soil urease activity to a certain extent.

[0141] After the application of microalgae fertilizer and nitrogen reduction treatment, the soil urease activity showed a significant downward trend from 60 to 120 days, showing N1W2>N2W2>N3W2>CK, and the difference between CK and soil urease activity was significant. During the period of 60 days to 100 days, the soil urease activity in the N1W2 treatment was the highest, and the soil urease activity at 60 days and 80 days increased by 13.6% and 22.5% respectively compared with CK. The soil urease activity reached the highest level at 100 days, which was 0.52 mg·g -1 ·d -1 This indicates that applying microalgae fertilizer and appropriately reducing nitrogen fertilizer can effectively maintain urease activity in the soil at a high level.

[0142] b. Effects of different fertilizer compositions on the activity of sucrase in beet soil are shown in Tables 6 and Figure 2 shown.

[0143] Table 6 Effects of different fertilizer combinations on sucrase activity in sugar beet soil (mg·g -1 ·d -1 )

[0144]

[0145]

[0146] The activity of soil sucrase (S-SC) is positively correlated with the transformation of organic matter in the soil. Figure 2The results show that when microalgae fertilizer was applied on the basis of chemical fertilizer, there was no significant difference among the treatments at 40 days of seedling age with the increase of microalgae fertilizer application. During the period of 60-100 days of seedling age, the soil urease activity increased first and then decreased with the increase of microalgae fertilizer application, showing NW2>NW3>NW1. And the soil urease activity of NW2 and NW3 treatments was significantly higher than that of CK. Among them, the soil urease activity of NW2 treatment reached the maximum at 100 days of seedling age, an increase of 22.2% compared with CK, while the soil urease activity of NW3 treatment reached the highest at 120 days of seedling age, an increase of 13.7% compared with CK. It shows that microalgae fertilizer has a promoting effect on the improvement of soil sucrase activity.

[0147] When the application rate of microalgae fertilizer is 9L / hm 2 Under the same conditions, the amount of nitrogen fertilizer was appropriately reduced, and the soil sucrase activity showed a significant downward trend during the 60-120 days, showing N1W2>N2W2>N3W2; among them, the soil sucrase activity in the N1W2 treatment was the highest in each growth period, increasing by 23.56%, 18.9%, 20.32%, and 24.81% compared with CK, respectively, and there were significant differences with CK except for the 40 days of seedling age. This shows that the application of microalgae fertilizer and the appropriate reduction of nitrogen fertilizer can effectively promote the activity of sucrase in the soil.

[0148] c. The effects of different fertilizer compositions on soil catalase activity are shown in Tables 7 and Figure 3 shown.

[0149] Table 7 Effects of different fertilizer compositions on soil catalase activity (μmol·h -1 ·g -1 )

[0150]

[0151] Soil catalase (S-CAT) is positively correlated with soil enzymatic reactions and can reduce the damage of excessive accumulation of hydrogen peroxide in the soil to plant roots. Figure 3 The results show that when microalgae fertilizer is applied on the basis of chemical fertilizer, with the increase of microalgae fertilizer application, soil urease activity shows a trend of first increasing and then decreasing during the seedling age of 80-120 days, and soil urease activity shows a gradual increase trend during the seedling age of 80-120 days, showing NW3>NW2>NW1, and reaches the maximum value at the seedling age of 100 days, increasing by 8.4%, 4.6%, and 2% respectively compared with CK. This shows that the application of microalgae fertilizer can promote soil catalase activity to a certain extent.

[0152] When the application rate of microalgae fertilizer is 9L / hm 2Under the same conditions, the amount of nitrogen fertilizer was appropriately reduced, and it showed a gradual decrease during the seedling age of 60-120 days, showing N1W2>N2W2>N3W2, among which N1W2 was significantly different from CK, increasing by 18.39%, 15.23%, 20.79%, and 17.28% respectively compared with CK. This shows that appropriate nitrogen reduction combined with microalgae fertilizer can effectively increase soil catalase activity.

[0153] d. The effects of different fertilizer compositions on soil polyphenol oxidase activity are shown in Table 8 and Figure 4 shown.

[0154] Table 8 Effects of different fertilizer combinations on soil polyphenol oxidase activity (μmol·h -1 ·g -1 )

[0155]

[0156]

[0157] Polyphenol oxidase (S-OOP) is an important oxidase in the process of humus synthesis, and it is negatively correlated with organic matter and humus in the soil. Figure 4 The results show that when microalgae fertilizer is applied in combination with chemical fertilizer, the change pattern of soil polyphenol oxidase activity during the seedling age of 60-120 days is CK>NW1, NW2>NW3 with the increase of microalgae fertilizer application rate. Among them, the soil polyphenol oxidase activity of NW3 treatment is the lowest and significantly different from CK. At the seedling age of 120 days, the soil polyphenol oxidase activity of NW3 treatment is 6.1% lower than that of CK, indicating that microalgae fertilizer treatment can maintain the activity of soil polyphenol oxidase at a low level.

[0158] When the application rate of microalgae fertilizer is 9L / hm 2 Under the same conditions, the amount of nitrogen fertilizer was appropriately reduced. The activity of soil polyphenol oxidase showed a continuous upward trend during the 80-120 days of seedling age, showing N1W2<N2W2<N3W2<CK. And the nitrogen reduction treatments were significantly different from CK. Among them, N1W2 was extremely different from CK, and it was reduced by 11.7%, 14.07% and 7.44% respectively during the 80-120 days of seedling age. The overall results show that nitrogen reduction combined with microalgae fertilizer treatment can effectively reduce soil polyphenol oxidase activity.

[0159] In summary, the application of different concentrations of microalgae fertilizer had different effects on soil enzyme activity at different stages of sugar beet production. 2The concentration of microalgae fertilizer increased the activities of soil urease, sucrase, and catalase during the growth period and was significantly higher than the control. The higher the concentration of microalgae fertilizer, the more obvious the effect of enhancing soil urease activity. The effect of microalgae fertilizer on soil peroxidase activity was more significant in the early growth period of beets, while the effect on polyphenol oxidase was significant after the microalgae entered the soil and fully multiplied and expanded. It can effectively reduce the activity of polyphenol oxidase in the soil in the late growth period.

[0160] (4) Effects of different fertilizer compositions on the abundance of sugar beet soil microbial communities

[0161] a. The effects of different fertilizer compositions on soil microbial community diversity are shown in Table 9.

[0162] Table 9 Effects of different fertilizer compositions on soil microbial community diversity

[0163]

[0164] By understanding the soil microbial diversity index, we can better understand the richness and distribution uniformity of soil microorganisms in the soil ecosystem, thereby evaluating the stability and health of the soil ecosystem. Three representative treatments were selected for soil microbial diversity evaluation: no microalgae fertilizer treatment (CK), microalgae fertilizer treatment (NW2) and microalgae fertilizer reduced nitrogen treatment (N3W2). Chao, Sobs and ACE indices are commonly used indices for estimating the total number of species in ecology, which can directly reflect the community richness, while the Shannon index can reflect the community diversity. As shown in Table 9, the Chao index, Sobs index, ACE index and Shannon index of the soil bacterial community in the three treatments of algae fertilizer treatments NW2 and N3W2 showed NW2>N3W2>CK, and the various indexes of NW2 treatment were significantly different from those of CK. This shows that the application of microalgae fertilizer can improve the richness and diversity of soil microbial communities to a certain extent, while the treatment of reduced nitrogen fertilizer will affect the richness and diversity of microbial communities in the soil.

[0165] b. Effects of different fertilizer combinations on soil community composition Figure 5 and Figure 6 shown.

[0166] Based on the results of taxonomic analysis, we can know the community structure composition of different groups (or samples) at various taxonomic levels (such as domain, kingdom, phylum, class, order, family, genus, species, ASV, etc.). Based on the community bar chart, two aspects of information can be intuitively presented: (1) what kind of microorganisms each sample contains at a certain taxonomic level; (2) the relative abundance (proportion) of each microorganism in the sample. Figure 5As shown, it can be clearly seen that the relative abundance of Actinobacteriota and Proteobacteria increased significantly under the treatment of microalgae fertilizer, and their abundance was NW2>N3W2>CK. Actinomycetes accounted for 37.05%, 27.69%, and 27.06%, respectively. Proteobacteria accounted for 28.22%, 23.35%, and 19.44%, respectively. The relative abundance of Acidobacteriota decreased in NW2 compared with CK, showing NW2<N3W3<CK, accounting for 13.23%, 18.40%, and 23.07%, respectively.

[0167] Circos Figure 6 The proportion of Actinobacteriota in each treatment is NW2>CK>N3W2, accounting for 12%, 11.34% and 10% on average, respectively. Soil actinomycetes can decompose organic matter and convert it into nutrients that can be used by plants, providing nutrients for plant growth. Secondly, antibiotics can be produced to inhibit the growth of other microorganisms and protect crops. In addition, soil actinomycetes can also fix nitrogen, provide nitrogen elements for plants, promote plant growth and development, decompose harmful substances, etc. This shows that microalgae fertilizer can increase the actinomycetes in the soil, but the application of the same microalgae fertilizer and the reduction of nitrogen fertilizer will reduce the actinomycetes in the soil.

[0168] The proportion of Proteobacteria in each treatment was NW2>N3W2>CK, accounting for 12%, 11%, and 10.34% on average, respectively. Proteobacteria plays an important role in ecological processes such as soil nitrogen cycle, organic matter decomposition, and soil remediation. This shows that the application of microalgae fertilizer can increase the number of Proteobacteria and is not affected by nitrogen fertilizer.

[0169] Sphingomonas has the ability to fix nitrogen or promote crop rhizosphere growth. The application of microalgae fertilizer promoted the increase in the relative abundance of Sphingomonas, which was NW2>N3W2>CK, with the proportions of each treatment being 43%, 30%, and 27%, respectively.

[0170] In summary, the application of microalgae fertilizer can increase the abundance of actinomycetes and proteobacteria in the soil, reduce the relative abundance of acidobacteria, increase the number of sphingomonas, and thus increase the number of beneficial bacteria.

[0171] (5) Effects of different fertilizer combinations on sugar beet morphological indicators

[0172] a. The effects of different fertilizer compositions on beet plant height are shown in Tables 10 and Figure 7 shown.

[0173] Table 10 Effect of different fertilizer combinations on beet plant height (cm)

[0174]

[0175] Plant height is one of the important growth indicators of sugar beet. The plant height is closely related to the strength of crop photosynthesis and the accumulation of dry matter. Figure 7 It can be seen that with the advancement of the growth period, the overall height of beet plants showed a trend of first increasing and then decreasing. It was the highest during the rapid growth period of leaf clusters (seedling age 80-100d) and gradually decreased during the sugar accumulation period (seedling age 120d). When microalgae fertilizer was applied on the basis of chemical fertilizer, with the increase of microalgae fertilizer application, the height of beet plants showed an increasing trend with the increase of microalgae fertilizer concentration at 40-80d of seedling age, which was NW3>NW2>NW1. It showed a trend of first increasing and then decreasing at 100-120d of seedling age, and was significantly higher than CK. After the application of microalgae fertilizer and nitrogen reduction treatment, the height of beet plants showed a trend of gradually decreasing with the reduction of nitrogen fertilizer. Among them, N1W2 and N2W2 treatments were significantly higher than CK. At 100d of seedling age, the height of beet plants reached the maximum value, which was 8.9% and 5.9% higher than CK, respectively. It shows that nitrogen reduction and microalgae fertilizer treatment are beneficial to promote the rapid growth of beet to a certain extent.

[0176] b. The effect of different fertilizer compositions on the number of sugar beet leaves is shown in Tables 11 and Figure 8 As shown, Figure 8 The groups corresponding to each column chart are Figure 7 .

[0177] Table 11 Effect of different fertilizer compositions on the number of sugar beet leaves (pieces / plant)

[0178]

[0179] Leaves play an indispensable role in the growth and development of plants. They are not only the site of photosynthesis and water transpiration, but also the basis of plant metabolic stability, directly affecting plant growth and yield. Figure 8 It can be seen that during the entire growth period of beet, the number of beet leaves showed a trend of first increasing and then decreasing as the growth period prolonged. During the root and sugar growth period (seedling age 100 days), the number of beet leaves reached the highest point during the growth period. Subsequently, due to the slow growth of new leaves and the accelerated shedding of senescent leaves, the number of leaves showed a period of stability and began to gradually decrease. In the period of 60-120 days of seedling age, the number of beet leaves increased first and then decreased as the application of microalgae fertilizer increased. Among them, the number of NW2 leaves increased significantly, and the difference was significant compared with CK; when the application of microalgae fertilizer was 9L / hm 2Under the same conditions, after the rapid growth period of leaves (seedling age 80 days), the number of beet leaves showed a downward trend with the decrease of nitrogen fertilizer application, showing N1W2>N2W2>N3W2>CK, and the N1W2 and N2W2 treatments were significantly different from CK. When the number of beet leaves reached the maximum at the 100th day of seedling age, it increased by 10.34% and 9.4% compared with CK, respectively. This shows that the application of appropriate chemical fertilizers combined with microalgae fertilizers is beneficial to the development of the aboveground part of beets.

[0180] c. The effects of different fertilizer compositions on the fresh weight of sugar beets are shown in Tables 12 to 13 and Fig. 9 As shown, Fig. 9 The groups corresponding to each column chart are Figure 7 .

[0181] Table 12 Effect of different fertilizer compositions on fresh weight of sugar beet above ground (kg / plant)

[0182]

[0183] Table 13 Effect of different fertilizer compositions on underground fresh weight of sugar beet (kg / plant)

[0184]

[0185]

[0186] From Tables 12 to 13 and Fig. 9 As shown, it is the fresh weight of the aboveground and underground parts of beets. During this period, the growth of various organs of beets was obvious. After the application of microalgae fertilizer, with the increase of microalgae fertilizer concentration, the leaves, petioles and tubers slowly increased; when the concentration of microalgae fertilizer remained unchanged, with the reduction of nitrogen fertilizer, the weight of various organs showed a downward trend. Among them, N1W2, which is a treatment with 10% nitrogen reduction, the weight of various organs is greater than that of the treatment without nitrogen reduction, and the difference is significant with CK.

[0187] During the sugar growth period (seedling age 100 days), the aboveground part grew slowly, and the beet roots expanded rapidly, and the weight almost reached the maximum value; at this time, the differences among the treatments were obvious. With the increase of microalgae fertilizer concentration, the aboveground part showed a slow increasing trend, and the underground part showed a rapid increasing trend, which was NW3>NW2>NW1. With the unchanged concentration of microalgae fertilizer, the beet roots showed a significant decreasing trend with the reduction of nitrogen fertilizer, which was N1W2>N2W2>N3W2>CK, and all of them were significantly different from CK, increasing by 26.8%, 23.1%, and 6.4% respectively compared with CK. This shows that the application of microalgae fertilizer or the application of microalgae fertilizer and the reduction of nitrogen fertilizer can promote the weight gain of the aboveground and underground parts of beets.

[0188] d. The effects of different fertilizer compositions on the accumulation of sugar beet dry matter are shown in Tables 14 to 15 and Figures 10-11 shown.

[0189] Table 14 Effect of different fertilizer compositions on dry matter accumulation in sugar beet leaves (g / plant)

[0190]

[0191] Table 15 Effect of different fertilizer compositions on the accumulation of dry matter in beetroot (g / plant)

[0192]

[0193] The dry matter of crops is the product of photosynthesis, and its accumulation and distribution are closely related to yield. Figures 10-11 It can be seen that the application of microalgae fertilizer on the basis of chemical fertilizer, during the entire growth period of beet, except for the seedling stage (seedling age 40d), there was no significant difference among the treatments. During the seedling age of 60-120d, the overall trend of the aboveground and underground dry matter accumulation of beet gradually increased with the increase of microalgae fertilizer application, showing NW3>NW2>NW1>CK, and all showed significant differences with CK. When the dry matter accumulation of NW3 treatment reached the maximum at the seedling age of 100d, the aboveground dry matter accumulation increased by 13.36% compared with CK, and the root dry matter accumulation increased by 11.9%. When the microalgae fertilizer application rate was 9L / hm 2 Under the same conditions, with the reduction of nitrogen fertilizer, the dry matter accumulation of the aboveground part during the 60-100 days of seedling age and the underground part during the 60-120 days of seedling age showed a gradual downward trend, showing N1W2>N2W2>N3W2>CK, and there were significant differences with CK. Among them, the dry matter accumulation of the underground part at the 120 days of seedling age increased by 24.59%, 21.85%, and 16.76% respectively compared with CK. This shows that appropriate nitrogen reduction and application of microalgae fertilizer can promote the accumulation of dry matter in sugar beet.

[0194] e. The effects of different fertilizer compositions on the root-crown ratio of beets are shown in Tables 16 and Fig.12 shown.

[0195] Table 16 Effect of different fertilizer combinations on sugar beet root-canopy ratio

[0196]

[0197] The root-to-crown ratio is the weight ratio of the underground part to the aboveground part of the plant, which can show the relationship between the underground part and the aboveground part of the plant during its growth and the transfer of the growth center. Fig.12It can be seen that the root-crown ratio of beets continues to increase with the growth period. When the tuber and sugar growth period (seedling age 100 days), the root-crown ratio is greater than 1, indicating that the growth center of beets has completed the transfer from the aboveground part to the underground part. In the period of 80-120 days of seedling age, with the increase of microalgae fertilizer concentration, the root-crown ratio of beets shows an upward trend, showing NW3>NW2>NW1>CK; when the application rate of microalgae fertilizer is 9L / hm 2 Under the same conditions, the root-to-crown ratio showed a downward trend with the reduction of nitrogen fertilizer, showing N1W2>N2W2>N3W2>CK, among which N1W2 and N2W2 treatments were significantly different from CK. When the root-to-crown ratio of sugar beets reached the maximum at 120 days of age, it was 24.58% and 23.46% higher than that of CK, respectively. This shows that the appropriate nitrogen reduction and microalgae fertilizer application have a significant effect on regulating the timely transfer of sugar beet growth center and improving the distribution of substances to the underground part.

[0198] Microalgae fertilizer concentration 12L / hm 2 Treatment is beneficial to promote the rapid growth of beets, and the concentration of 9L / hm 2 Treatment is more conducive to increasing the number of beet leaves, making its root-crown ratio more advantageous in the tuber and sugar growth period, and more conducive to the accumulation of dry matter and the improvement of sugar content in beet. Considering the planting cost and comprehensive characteristics of beet, 9L / hm2 is recommended for production 2 The application of microalgae fertilizer with a concentration of 1.5-2.0 was the best application amount. In summary, the application of microalgae fertilizer had a significant effect on improving the plant height and leaf number of beets in the early and middle growth stages of beets, and had a significant effect on improving the fresh weight of tubers in the tuber and sugar growth period.

[0199] f. Effects of different fertilizer combinations on sugar beet photosynthetic indicators

[0200] The effects of different fertilizer combinations on the photosynthetic rate of sugar beet net leaves are shown in Tables 17 and Fig.13 shown.

[0201] Table 17 Effects of different fertilizer compositions on the photosynthetic rate of sugar beet net leaves (unit: μmol / m 2 s)

[0202]

[0203]

[0204] The level of plant net photosynthetic rate directly reflects the photosynthetic performance level of leaves and is a key indicator for measuring photosynthetic efficiency. Fig.13It can be seen that the net photosynthetic rate of beet showed a trend of first increasing and then decreasing with the growth period, and the net photosynthetic rate of beet leaves reached the highest during the rapid growth period of leaf clusters (60-80d). Microalgae fertilizer was applied on the basis of chemical fertilizers. With the increase of the application amount of microalgae fertilizer, the net photosynthetic rate of beet showed an upward trend, showing NW3>NW2>NW1>CK, which was significantly different from CK. When each treatment reached the maximum value at 80d of seedling age, the net photosynthetic rate of beet increased by 18.5%, 11.88%, and 10.08% respectively compared with CK. This shows that the application of microalgae fertilizer can increase the net photosynthetic rate of beet leaves, and it is particularly obvious during the rapid growth period of leaf clusters. When the application amount of microalgae fertilizer is 9L / hm 2 Under the same conditions, with the reduction of nitrogen fertilizer, the net photosynthetic rate of sugar beet at 60-120 days of seedling age generally showed a downward trend, which was basically N1W2>N2W2>N3W2>CK, and there were significant differences compared with CK, with N1W2 increasing by 16.2% compared with CK. This shows that appropriate nitrogen reduction combined with microalgae fertilizer can maintain the net photosynthetic rate of sugar beet leaves at a high level, while excessive nitrogen reduction will significantly reduce the photosynthetic rate of sugar beet.

[0205] The effects of different fertilizer compositions on the SPAD values ​​of sugar beet net leaves are shown in Tables 18 and Fig.14 shown.

[0206] Table 18 Effect of different fertilizer compositions on the SPAD value of sugar beet net leaves

[0207]

[0208] The leaf SPAD value is an important parameter to measure the relative content of plant chlorophyll and an important indicator to evaluate the growth status of crops. Fig.14 It can be seen that with the advancement of the growth period, the SPAD value of beet leaves showed a slow trend of first increasing and then decreasing. When microalgae fertilizer was applied on the basis of chemical fertilizer, the leaf SPAD value showed a gradual upward trend with the increase of microalgae fertilizer application at 40-120 days of seedling age, showing NW3>NW2>NW1>CK, and at 60-80 days of seedling age, the differences between each treatment and CK were significant. This shows that the application of microalgae fertilizer can increase the chlorophyll content of beet leaves to a certain extent. When the application rate of microalgae fertilizer was 9L / hm 2 Under the same conditions, with the reduction of nitrogen fertilizer, the leaf SPAD value showed a downward trend during the 60-120 days of seedling age, showing N1W2>N2W2>N3W2>CK, among which there was no significant difference between the N1W2 and N2W2 treatments, but both were significantly different from CK; when the leaf SPAD values ​​of the above two treatments reached the maximum value at the 100th day of seedling age, they were 5.5% and 5% higher than those of CK, respectively. This shows that appropriate nitrogen reduction combined with microalgae fertilizer can stabilize the chlorophyll content of plants at a higher level.

[0209] The application of microalgae fertilizer can effectively increase the SPAD value of beet leaves, increase the content of leaf photosynthetic pigments, promote the net photosynthetic rate of beet leaves, maintain a relatively high photosynthetic performance of beets during the rapid growth period of leaves, and be beneficial to the accumulation of dry matter mass of root tubers in the late growth period. The root-crown ratio of beets is significantly increased in the late growth period, and ultimately effectively increase the yield and sugar content of beet tubers, thereby achieving increased production and efficiency of beets.

[0210] g. The effects of different fertilizer compositions on nitrogen absorption by sugar beet plants are shown in Table 19.

[0211] Table 19 Effects of different fertilizer combinations on nitrogen content in the aboveground and underground parts of sugar beets (unit: mg / plant)

[0212]

[0213] Nitrogen is very important for plant growth. It is an essential element for the formation of proteins, cell walls, nucleic acids and amino acids. As shown in Table 19, with the advancement of the growth period of beets, the nitrogen content in the aboveground and underground parts of beets gradually increased. Microalgae fertilizer was applied on the basis of chemical fertilizers. With the increase of the application amount of microalgae fertilizer, the nitrogen content in the aboveground and underground parts of beets showed the same gradual increase trend. The specific treatments were NW3>NW2>NW1>CK. At the age of 100 days, the nitrogen content in the aboveground part reached the highest value. The nitrogen content in the aboveground part of beets in NW1, NW2 and NW3 treatments increased by 12.6%, 13.8% and 16.21% respectively compared with CK; the nitrogen content in the underground part increased by 4%, 4.5% and 12.8% respectively compared with CK. It shows that the application of microalgae fertilizer can increase the nitrogen content in the aboveground and underground parts of beets. When the application amount of microalgae fertilizer is 9L / hm 2 Under the same conditions, the nitrogen content of the aboveground and underground parts of beets showed a gradual downward trend as the nitrogen fertilizer was reduced, but they were higher than CK to varying degrees. When the nitrogen content of the aboveground and underground parts of beets reached the highest at 100d and 120d, the N1W2 treatment had the most obvious advantage, which was significantly different from CK. At 120d, the nitrogen content of the underground part of beets was 28% higher than that of CK. This shows that appropriate nitrogen reduction combined with microalgae fertilizer can enhance the nitrogen absorption capacity of beets.

[0214] The nitrogen-fixing cyanobacteria in the microalgae fertilizer effectively increases the nitrogen content of the above-ground and underground parts of the plants by fixing nitrogen in the atmosphere and soil. At the same time, the photosynthetic green algae, which accounts for 40% of the microalgae fertilizer, can form an internal and external symbiotic relationship with the plant roots, improving the nitrogen utilization efficiency of the plant roots.

[0215] h. Effect of microalgae fertilizer application on sugar beet root hair structure

[0216] The structure of root hairs of sugar beets in N1W2 test group and CK control test group was observed when sugar beets entered the rapid leaf growth period at 60 days old.

[0217] Effects of microalgae fertilizer application on the root hair structure of sugar beet Figures 15-16 As shown. Fig.15 Microscopic structure of beet root hairs for the application of microalgae fertilizer; Fig.16 This is a microscopic picture of the root hairs of beets without the application of microalgae fertilizer.

[0218] from Fig.15 and 16 The results of the effects of different microalgae fertilizers on the root hair structure of sugar beet showed that the application of microalgae fertilizer was effective when sugar beet entered the rapid growth period of leaf clusters (seedling age 60 days) ( Fig.15 ), the presence of a green material covering layer can be clearly observed around the root hairs. This covering layer is formed by the active cells of green algae attached to the root hairs and the surface of the beet root hairs to form an external symbiotic relationship. The nutrients produced by the microalgae during the growth process can be directly absorbed and utilized by the beet root system, which is beneficial to the growth and development of the beet. Fig.16 ) were not observed to have active microalgae cells attached around the root hairs of beets.

[0219] (6) Correlation analysis between different fertilizer combinations and sugar beet yield and quality

[0220] a. Correlation analysis between soil characteristic indexes and sugar beet yield and quality Fig.17 shown.

[0221] from Fig.17 The results showed that beet yield was significantly positively correlated with urease, catalase, and alkaline nitrogen. 2 The value was between 0.96 and 0.82, and was positively correlated with sucrase and pH value, but it did not reach a significant level. 2 was between 0.75 and 0.34, and was significantly negatively correlated with polyphenol oxidase; the sugar content of beets was significantly positively correlated with alkaline nitrogen, R 2 was 0.81, and was positively correlated with urease, sucrase, catalase, and pH value, but did not reach a significant level. 2 The value of R was between 0.58 and 0.30, and was negatively correlated with polyphenol oxidase but did not reach a significant level. The sugar yield of sugar beet was significantly positively correlated with urease, catalase, and alkaline nitrogen. 2 was between 0.87 and 0.76; it was positively correlated with sucrase and pH value but did not reach a significant level. 2 It was between 0.68 and 0.34, and was significantly negatively correlated with polyphenol oxidase. In summary, the application of chemical fertilizers combined with microalgae fertilizers significantly improved the yield and quality of sugar beets, and had a significant effect on the enhancement of urease and catalase activities and the increase of soil alkaline nitrogen content.

[0222] b. Analysis of correlation between sugar beet physiological characteristics and sugar beet yield and quality Fig.18 .

[0223] like Fig.18 As shown in the figure, beet yield was significantly positively correlated with plant height, leaf number, fresh weight, dry matter accumulation, root-shoot ratio, SPAD value, and net photosynthetic rate. 2 was between 0.97 and 0.84; it was positively correlated with the nitrogen content of sugar beet but did not reach a significant level. 2 is 0.72; sugar content of beet is significantly positively correlated with leaf number and dry matter accumulation, R 2 The value was 0.83-0.80, and was positively correlated with plant height, fresh weight, root-to-shoot ratio, SPAD value, net photosynthetic rate, and nitrogen content, but did not reach a significant level. 2 The sugar yield of sugar beet was significantly positively correlated with plant height, leaf number, fresh weight, dry matter accumulation, root-shoot ratio, SPAD value, and net photosynthetic rate. 2 The values ​​were between 0.96 and 0.87, and were positively correlated with the nitrogen content index but did not reach a significant level. 2 The above analysis shows that the application of microalgae fertilizer combined with chemical fertilizer can significantly increase sugar beet yield and sugar production, and has a significant impact on sugar beet plant height, leaf number, fresh weight, dry matter accumulation, root-to-crown ratio, SPAD value, and net photosynthetic rate.

[0224] (7) The economic benefit analysis of sugar beets under different fertilizer combination treatments is shown in Table 20.

[0225] Table 20 Economic benefit analysis of sugar beet under different fertilizer combinations

[0226] deal with <![CDATA[Yield (kg / hm 2 )]]> <![CDATA[Total output value (yuan / hm 2 )]]> <![CDATA[Cost input (yuan / hm 2 )]]> <![CDATA[Net income (yuan / hm 2 )]]> NW1 66574.23±1003.98b 38613.05 27040 11573.5±95.78d NW2 67875.34±901.90ab 39367.70 27060 12307.7±155.24cd NW3 68278.09±893.61ab 39601.29 27080 12521.29±86.35c N1W2 70480.86±759.28a 40878.90 27028 13850.9±141.28a N2W2 69230.08±941.73a 40153.45 26996 13157.45±83.05b N3W2 66347.87±881.78b 38481.76 26964 11517.76±99.31d CK 63624.25±876.32c 36902.07 27000 9902.07±107.82e

[0227] Note: The purchase price of sugar beet in 2023-2024 is 0.58 yuan / kg, and the price of microalgae liquid fertilizer is 9L / hm 2 The cost input includes irrigation, fertilization input + production cost. The production cost includes land rental fee, paper tube seedling production materials, sub-film drip irrigation system, pesticides, and labor, totaling 27,000 yuan / hm2.

[0228] The economic benefits of sugar beets directly affect the income increase of growers and enterprises and the sustainable development of the industry. As shown in Table 20, the total output value of sugar beets treated with microalgae fertilizer and microalgae fertilizer with reduced nitrogen was significantly higher than that of CK, and the economic benefits increased by 3976.83 to 1579.69 yuan / hm2 compared with CK. 2 From the perspective of maximizing economic benefits, the total output value of N1W2 treatment was the highest, reaching 40878.90 yuan / hm 2 After deducting the cost, the net profit is the highest among all treatments, and the net profit can be 13850.9 yuan / hm 2 , an increase of 3948.83 yuan / hm2 compared with CK2 , which has application and promotion value in sugar beet production.

[0229] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A microalgae nutrient solution, characterized in that: According to the percentage of single algae cells, the content includes: 30% to 50% of nitrogen-fixing cyanobacteria No. 1, 10% to 20% of nitrogen-fixing cyanobacteria No. 2, and 40% to 50% of photosynthetic green algae; the single algae cell content in the microalgae nutrient solution is ≥ 1.0×10 6 Pieces / mL; The nitrogen-fixing cyanobacteria No. 1 includes Anabaena; and the nitrogen-fixing cyanobacteria No. 2 includes Monochamus.

2. The microalgae nutrient solution according to claim 1, characterized in that: The microalgae nutrient solution, calculated by algae single cell percentage, comprises: Nitrogen-fixing cyanobacteria No. 1 40%, nitrogen-fixing cyanobacteria No. 2 20% and photosynthetic green algae 40%.

3. A fertilizer composition, characterized in that It comprises the microalgae nutrient solution and inorganic fertilizer as described in claim 1 or 2.

4. Use of the microalgae nutrient solution according to claim 1 or 2 or the fertilizer composition according to claim 3 in promoting sugar beet growth and / or improving soil physical and chemical properties.

5. According to the use of claim 4, the method for promoting the growth of sugar beet comprises any one or more of the following (1) to (9): (1) Increase sugar beet yield; (2) Increase sugar yield in sugar beets; (3) Increase beet plant height; (4) Increase the number of beet leaves; (5) increasing the fresh weight and / or dry weight of sugar beets; (6) Improve the root-to-shoot ratio of sugar beets; (7) Increase the photosynthetic rate of sugar beets; (8) Increase leaf chlorophyll content; (9) Enhance the nitrogen absorption capacity of beets.

6. The use according to claim 5, characterized in that: Increasing the fresh weight and / or dry weight of sugar beets includes any one or more of increasing the fresh weight and / or dry weight of sugar beets above ground, increasing the fresh weight and / or dry weight of sugar beets underground, increasing the dry matter accumulation of sugar beet leaves, and increasing the dry matter accumulation of sugar beet roots.

7. The use according to claim 4, characterized in that: The improvement of soil physical and chemical properties includes any one or more of the following (a) to (d): (a) Improve soil pH; (b) increase soil alkaline nitrogen; (c) Improve soil enzyme activity; (d) Improve soil microbial community.

8. The use according to claim 7, characterized in that: The improving soil enzyme activity includes any one or more of increasing the urease activity in the soil, increasing the sucrase activity in the soil, increasing the catalase activity in the soil and reducing the polyphenol oxidase activity in the soil; the improving the soil microbial community includes any one or more of increasing the richness of the soil microbial community, increasing the number of actinomycetes, increasing the number of proteobacteria, reducing the relative abundance of acidobacilli and increasing the number of sphingomonas.

9. A method for fertilizing beets, characterized in that: include: Applying basal fertilizer when planting beets; the basal fertilizer includes nitrogen fertilizer, phosphorus fertilizer and potash fertilizer; The microalgae nutrient solution of claim 1 or 2 is applied to 15 true leaves of beet seedlings.

10. The fertilization method according to claim 9, characterized in that: The application amount of the microalgae nutrient solution is 6 to 12 L / hm 2 ; The application rate of the nitrogen fertilizer is 94.5~135kg / hm 2 .

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