Water-soluble fertilizer for promoting color change of tomatoes and preparation method of water-soluble fertilizer

Abstract

The invention discloses a water-soluble fertilizer for promoting tomato color change and a preparation method thereof, and relates to the technical field of fertilizers, the water-soluble fertilizer comprises the following raw materials by weight: 15-25 parts of a nitrogen source raw material, 10-25 parts of a phosphorus source raw material, 45-65 parts of a potassium source raw material, 1-2 parts of a magnesium source raw material, and 0.1-0.5 part of astaxanthin. According to the water-soluble fertilizer prepared by the preparation method disclosed by the invention, large, medium and trace elements such as nitrogen, phosphorus, potassium, calcium, magnesium, zinc and boron are reasonably prepared according to physiological demand characteristics of tomatoes in a fruit swelling period, astaxanthin is added, the activity of astaxanthin is ensured, function exertion and a coloring effect tend to be synergistic by strictly controlling an addition amount ratio, and the effects of improving the coloring quality of the tomatoes and increasing the yield are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of fertilizers, and in particular to a water-soluble fertilizer for promoting tomato color change and a preparation method thereof. Background Art

[0002] Fruit color is one of the important indicators of its commercial quality. Fruit color is mainly determined by the pigment composition of the fruit. The essence of fruit color change is the metabolism of chlorophyll in the fruit, part of the chlorophyll is converted into carotenoids, and anthocyanins begin to accumulate in large quantities, so that the fruit shows brilliant colors.

[0003] The color of tomato peels greatly affects consumers' choices. However, in tomato planting, it is easy to have slow color change or poor coloring of the fruit, which directly affects the fruit quality and commerciality of tomato agricultural products and has a relatively serious impact on planting. The main reasons are insufficient nutrients in the soil and the ambient temperature. When planting tomatoes, physiological diseases such as difficulty in color change or deformity, navel rot, etc. may occur in hot weather or under nutrient deficiency. At present, the existing technology adopts more spraying of plant regulators or foliar fertilizers on the whole plant, or directly accelerating the redness of the fruit after picking, so as to improve the commerciality of tomatoes and realize the early listing of tomatoes. However, in the implementation process, the timing and amount of operation are difficult to control. Excessive or residual on the leaves can easily cause the plant to wither, which is inconvenient to operate, and is prone to drug damage and fertilizer damage, which is not conducive to the commerciality and healthy implementation of healthy tomato products.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] In view of the existing problems, the present invention provides a water-soluble fertilizer for promoting color change of tomatoes, which not only effectively improves the stress resistance of tomatoes in high temperature weather but also improves the quality of tomatoes, enhances the ability of tomatoes to cope with stress environments during tomato fruit setting, but also promotes the synthesis rate of lycopene to enhance and change the color change effect, thereby improving the quality of tomato products.

[0006] The first object of the present invention is to provide a water-soluble fertilizer for promoting tomato color change, comprising the following raw materials in parts by weight: 15-25 parts of nitrogen source raw materials, 10-25 parts of phosphorus source raw materials, 45-65 parts of potassium source raw materials, 1-2 parts of magnesium source raw materials and 0.1-0.5 parts of astaxanthin.

[0007] In some preferred embodiments, the nitrogen source raw material is at least one of urea, ammonium sulfate and ammonium bicarbonate; the phosphorus source raw material is at least one of industrial monoammonium, ammonium polyphosphate and nitrophosphate compound fertilizer; the potassium source raw material is at least one of potassium sulfate, potassium carbonate and potassium chloride; the magnesium source raw material is at least one of magnesium sulfate, magnesium nitrate and magnesium chloride.

[0008] The second object of the present invention is to provide a method for preparing astaxanthin for preparing a water-soluble fertilizer that promotes tomato color change, the steps of which include: inoculating crimson yeast in a prepared first fermentation medium for culturing and screening, inoculating crimson yeast screened by the first fermentation medium in a prepared second fermentation medium for fermentation, and after the fermentation is completed, centrifuging the fermentation liquid, taking the supernatant after centrifugation, evaporating and concentrating, adding dimethyl sulfoxide and ethanol for extraction, and finally drying and concentrating to constant weight to prepare the product.

[0009] In some preferred embodiments, the first fermentation medium comprises 20-25 g / L glucose, 10-15 g / L beef peptone, 5.5-6 g / L yeast extract, 8.5-10 g / L sodium chloride, 1.5-2 g / L magnesium sulfate and 5-6 g / L potassium dihydrogen phosphate, which are mixed evenly, adjusted to pH 4.5-5, and sterilized;

[0010] The second fermentation medium includes 20-25 g / L glucose, 10-15 g / L beef peptone, 15-20 g / L yeast extract, 8.5-10 g / L sodium chloride, 0.1-0.2 g / L magnesium sulfate, 0.15-0.2 g / L potassium hydrogen phosphate, and 0.65-1 g / L Tween, which are mixed evenly, adjusted to pH 4.5-5, and sterilized.

[0011] In some preferred embodiments, the fermentation is inoculated with 4-6% red yeast and cultured at 24-28° C. for 3-4 days.

[0012] In some preferred embodiments, the mass ratio of the dimethyl sulfoxide to the ethanol is 2.7-3:1.8-2, and the pH value of the extraction is 5.5-6.0.

[0013] In some preferred embodiments, the evaporation concentration is performed using a rotary evaporator at 40-45 rpm and 40-45°C.

[0014] In some preferred embodiments, the dry concentration is performed in a nitrogen generator.

[0015] The third object of the present invention is to provide a method for preparing a water-soluble fertilizer for promoting tomato color change, the steps of which include: heating and melting a nitrogen source, then passing it into a primary mixing tank, and adding a potassium source to the primary mixing tank, then passing the molten mixture in the primary mixing tank into a secondary mixing tank, and adding a phosphorus source and a magnesium source to the secondary mixing tank, and again passing the molten mixture in the secondary mixing tank into a granulating device for granulation, and finally cooling and solidifying to obtain a granular composite fertilizer, dissolving astaxanthin with anti-caking oil, and evenly spraying it on the surface of the composite fertilizer to prepare a water-soluble fertilizer for promoting tomato color change.

[0016] In some preferred embodiments, the granulation method is any one of high tower granulation, rotary drum fluidized bed granulation, disc granulation, and spray granulation.

[0017] The present invention has the following beneficial effects:

[0018] 1. The water-soluble fertilizer prepared by the present invention is configured with multiple nutrients through a scientific formula: the water-soluble fertilizer is reasonably matched with nitrogen, phosphorus, potassium, magnesium and other macro- and micro-elements according to the physiological needs of tomatoes during the fruit expansion period, and active astaxanthin is added at the same time, which fully meets the nutrients required for the growth and development of tomatoes and lays a good nutritional foundation for the expansion of fruits and the improvement of quality.

[0019] 2. The technical solution of the present invention utilizes the unique effect of astaxanthin to synergistically improve color change and yield: by utilizing the property of astaxanthin that can promote the large-scale synthesis of related synthases, relying on its strong oxidizing and high permeability to accelerate cytoplasmic flow and enhance metabolism, natural coloring and uniform color effects are achieved, and by strictly controlling the addition ratio, the function of astaxanthin is synergistically coordinated with the color change effect, ultimately achieving the purpose of improving the color change quality of tomatoes and increasing yields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 SPAD changes in tomato leaves;

[0022] Figure 2 The wilting of tomato leaves;

[0023] Figure 3 This is a comparative test of single fruit weight of tomatoes;

[0024] Figure 4 This is a comparative test of tomato deformed fruits;

[0025] Figure 5 This is a comparative test on tomato fruit cracking. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0027] The water-soluble fertilizer for promoting tomato color change and the preparation method thereof provided by the present invention are specifically described below.

[0028] The invention provides a water-soluble fertilizer for promoting tomato color change, comprising the following raw materials in parts by weight: 15-25 parts of nitrogen source raw materials, 10-25 parts of phosphorus source raw materials, 45-65 parts of potassium source raw materials, 1-2 parts of magnesium source raw materials and 0.1-0.5 parts of astaxanthin.

[0029] Astaxanthin, with its unique molecular structure and strong antioxidant capacity, activates the activity of various physiological and biochemical enzymes in cells, accelerates the accumulation of dry matter and sugar in plant cells, promotes the activity of anthocyanin synthase, accelerates pigment deposition, and thus helps growers grow high-quality healthy agricultural products with high sugar content, bright color, and good taste. First of all, astaxanthin promotes the massive synthesis of carotenoid synthase and anthocyanin synthase, directly acts on the key metabolic pathways of fruit color change, promotes the natural color change of plants, and makes the fruit color uniform and bright. At the same time, astaxanthin can increase the massive synthesis of crop photosynthesis factors, promote the accumulation of dry matter in cells, and increase VC content. Through two-way regulation, it can restore its natural flavor and increase the sugar content of the fruit. Secondly, astaxanthin is the substance with the strongest antioxidant capacity in nature. It can remove nitrogen dioxide, sulfide, disulfide, etc., reduce lipid peroxidation, and effectively inhibit lipid peroxidation caused by free radicals. In addition, astaxanthin can enhance the aggregation force between cells, enhance cell regeneration ability, inhibit the formation of ROS and MPS, effectively remove free radicals that cause peel aging and cell tissue necrosis, and extend the storage period of the fruit.

[0030] In some preferred embodiments, the nitrogen source raw material is at least one of urea, ammonium sulfate and ammonium bicarbonate; the phosphorus source raw material is at least one of industrial monoammonium, ammonium polyphosphate and nitrophosphate compound fertilizer; the potassium source raw material is at least one of potassium sulfate, potassium carbonate and potassium chloride; the magnesium source raw material is at least one of magnesium sulfate, magnesium nitrate and magnesium chloride.

[0031] Scientifically adding nitrogen, phosphorus, potassium and magnesium to fertilizers for growing tomatoes has many benefits. Nitrogen can promote the growth of plants, improve photosynthesis efficiency, and allow leaves to produce more nutrients; phosphorus can stimulate root development, build a solid foundation for plants, and help flower bud differentiation and fruit ripening, improving fruit quality; potassium can enhance plant stress resistance, allowing them to better adapt to adverse environments, and can also optimize the taste, color and storage of fruits; magnesium, as the central atom of chlorophyll, ensures the normal progress of photosynthesis, activates the activity of multiple enzymes, and participates in many physiological processes. The four work together to lay a solid foundation for high-quality and high-yield tomatoes.

[0032] Secondly, the present invention also provides a method for preparing astaxanthin for preparing a water-soluble fertilizer that promotes tomato color change, the steps of which include: inoculating crimson yeast in a prepared first fermentation medium for culturing and screening, inoculating crimson yeast screened by the first fermentation medium in a prepared second fermentation medium for fermentation, and after the fermentation is completed, centrifuging the fermentation liquid, taking the supernatant after centrifugation, evaporating and concentrating, adding dimethyl sulfoxide and ethanol for extraction, and finally drying and concentrating to constant weight to prepare the product.

[0033] Among them, the use of the first fermentation medium can provide a more suitable growth environment for microorganisms. During the culture process of the first culture medium, the rapid reproduction of microorganisms can be emphasized, so that the number of microbial cells increases significantly. Then, during the culture process in the second culture medium, the composition and culture conditions of the culture medium can be used to induce microorganisms to synthesize astaxanthin in large quantities.

[0034] In some preferred embodiments, the first fermentation medium comprises 20-25 g / L glucose, 10-15 g / L beef peptone, 5.5-6 g / L yeast extract, 8.5-10 g / L sodium chloride, 1.5-2 g / L magnesium sulfate and 5-6 g / L potassium dihydrogen phosphate, which are mixed evenly, adjusted to pH 4.5-5, and sterilized;

[0035] The second fermentation medium includes 20-25 g / L glucose, 10-15 g / L beef peptone, 15-20 g / L yeast extract, 8.5-10 g / L sodium chloride, 0.1-0.2 g / L magnesium sulfate, 0.15-0.2 g / L potassium hydrogen phosphate, and 0.65-1 g / L Tween, which are mixed evenly, adjusted to pH 4.5-5, and sterilized.

[0036] Among them, Tween was added to the second fermentation medium to adjust the medium composition, which can ensure a more even distribution of the yeast on the medium. Magnesium sulfate and potassium dihydrogen phosphate are used to add inorganic salts to the strain. The increase in content is to adjust the pH of the medium and promote the growth of yeast strains.

[0037] In some preferred embodiments, the fermentation is inoculated with 4-6% red yeast and cultured at 24-28° C. for 3-4 days.

[0038] Among them, crimson yeast is selected because it is relatively easy to culture, has no strict requirements on the growth environment, and can grow and reproduce under common laboratory conditions or industrial fermentation conditions; crimson yeast has improved its astaxanthin production through optimizing culture conditions and strain selection, and has great production potential; compared with some natural astaxanthin production methods, crimson yeast has a relatively short fermentation production cycle, which can obtain products faster and improve production efficiency; by controlling fermentation conditions and extraction processes, astaxanthin products with relatively stable quality can be obtained. Compared with chemically synthesized astaxanthin, astaxanthin produced by biological fermentation is closer to natural astaxanthin in structure and biological activity, and does not have the problems of harmful substance residues that may be produced during chemical synthesis, and has higher safety and bioavailability; while producing astaxanthin, crimson yeast itself can also be used as a high-quality protein source, and its cells are rich in amino acids, B vitamins, and nutrients such as manno-oligosaccharides and glucans in yeast cell walls.

[0039] In some preferred embodiments, the mass ratio of the dimethyl sulfoxide to the ethanol is 2.7-3:1.8-2, and the pH value of the extraction is 5.5-6.0.

[0040] In some preferred embodiments, the evaporation concentration is performed using a rotary evaporator at 40-45 rpm and 40-45°C.

[0041] In some preferred embodiments, the dry concentration is performed in a nitrogen generator.

[0042] Because astaxanthin is a strong antioxidant, the polyene bonds in its chemical structure are easily oxidized. During the drying process, if oxygen is present, the polyene bonds of astaxanthin will react with oxygen, causing the astaxanthin to be oxidized. This oxidation reaction will not only reduce the content of astaxanthin, but also change its chemical structure, reducing or even losing its antioxidant activity. Using a nitrogen generator can effectively isolate oxygen. When astaxanthin is dried in an anaerobic environment, the risk of oxidation is greatly reduced, which can extend the shelf life of the product.

[0043] Finally, the present invention provides a method for preparing a water-soluble fertilizer for promoting tomato color change, the steps of which include: heating and melting a nitrogen source, then passing it into a primary mixing tank, and adding a potassium source into the primary mixing tank, then passing the molten mixture in the primary mixing tank into a secondary mixing tank, and adding a phosphorus source and a magnesium source into the secondary mixing tank, again passing the molten mixture in the secondary mixing tank into a granulating device for granulation, and finally cooling and solidifying to obtain a granular composite fertilizer, dissolving astaxanthin with anti-caking oil, and evenly spraying it on the surface of the composite fertilizer to prepare a water-soluble fertilizer for promoting tomato color change.

[0044] In some preferred embodiments, the granulation method is any one of high tower granulation, rotary drum fluidized bed granulation, disc granulation, and spray granulation.

[0045] Example 1

[0046] The present embodiment provides a water-soluble fertilizer for promoting color change of tomatoes, which is made of the following raw materials in the following weight ratio: 16 parts of urea, 16 parts of industrial monoammonium, 61 parts of potassium sulfate, 2 parts of EDTA-Ga, 2 parts of magnesium sulfate, and 0.5 parts of astaxanthin.

[0047] The preparation method of the water-soluble fertilizer for promoting tomato color change is as follows:

[0048] The urea is heated and melted, and then passed into a primary mixing tank, and potassium sulfate is added to the primary mixing tank. Next, the molten mixture in the primary mixing tank is passed into a secondary mixing tank, and EDTA-Ga, industrial monoammonium and magnesium sulfate are added to the secondary mixing tank. The molten mixture in the secondary mixing tank is again passed into a high tower granulation device for granulation, and finally cooled and solidified to obtain a granular compound fertilizer. After astaxanthin is dissolved with anti-caking oil, it is evenly sprayed on the surface of the compound fertilizer to prepare a water-soluble fertilizer that promotes tomato color change.

[0049] Example 2

[0050] The other steps and parameters of this embodiment are the same as those of embodiment 1, except that:

[0051] The water-soluble fertilizer for promoting tomato color change is made of the following raw materials in the following weight ratio: 16 parts of urea, 16 parts of industrial monoammonium, 61 parts of potassium sulfate, 2 parts of EDTA-Ga, 2 parts of magnesium sulfate, and 0.3 parts of astaxanthin.

[0052] Example 3

[0053] The other steps and parameters of this embodiment are the same as those of embodiment 1, except that:

[0054] The water-soluble fertilizer for promoting tomato color change is made of the following raw materials in the following weight ratio: 16 parts of urea, 16 parts of industrial monoammonium, 61 parts of potassium sulfate, 2 parts of EDTA-Ga, 2 parts of magnesium sulfate, and 0.1 parts of astaxanthin.

[0055] Comparative Example 1

[0056] The other steps and parameters of this embodiment are the same as those of embodiment 1, except that:

[0057] The water-soluble fertilizer for promoting tomato color change is made of the following raw materials in the following weight ratio: 16 parts of urea, 16 parts of industrial monoammonium, 61 parts of potassium sulfate, and 2 parts of magnesium sulfate.

[0058] Test Example 1

[0059] The present invention is used to plant "Provence" tomatoes in Bao'an District, Guangdong Province in summer in June, with a growth period of about 125-145 days, and enters the flowering and fruiting period in mid-to-late July. Seedlings are raised in seedling trays, transplanted when there are 3-4 true leaves, and one tree is planted in each pot. 15-15-15 water-soluble fertilizer is applied in the base fertilizer and seedling stage, and the water-soluble fertilizer for promoting tomato color change and clear water in Examples 1-3 are respectively used as the control group, and 25 kg of fertilizer is applied per mu each time, and fertilizer is applied 4 times in total in the flowering and fruiting period, the young fruit period, the fruit expansion period, and the harvest period. Each fertilization is carried out by drip irrigation, and the fertilizer-water ratio is 1:600. The experiment was conducted outside the experimental platform. The average daytime temperature was 33-36°C, and the highest temperature could reach 37°C. There were no shade nets or other shelters. Pay attention to avoiding rain. Water the plants in the morning and evening according to the dryness and wetness of the soil. Observe the leaves of each group of tomatoes, measure the SPAD value of the tomato leaves with a chlorophyll meter, and calculate the leaf wilting rate (leaf wilting rate = number of wilted leaves ÷ total number of leaves): the total number of leaves and the number of wilted leaves of each genotype in the control group and the treatment group were counted respectively. If more than half of the leaves were wilted, it was recorded as 1, if no more than half of the leaves were wilted, it was recorded as 0.5, and if there was no wilting symptom, it was recorded as 0. The results are as follows: Figure 1 and Figure 2 shown.

[0060] Depend on Figure 1 It can be seen that the SPAD values ​​of tomato leaves under different treatments increased over time, and the SPAD values ​​of the leaves in Example 2 were significantly higher than those in the control group, indicating that the chlorophyll content of the tomato leaves in Example 2 increased significantly. Figure 2 It can be seen that the leaf wilting rate of Example 2 is 30.6%, the leaf wilting rate of Example 1 is 35.4%, the leaf wilting rate of Example 3 is 46.1%, and the leaf wilting rate of the control example is 65.2%. A leaf wilting rate that is too high indicates that the water loss in the plant body is too fast, and the plant will show symptoms such as slow growth, leaf wilting and yellowing, or even death, which shows that Example 2 can significantly reduce leaf wilting.

[0061] Test Example 2

[0062] The present invention is used for planting "Provence" tomatoes in Bao'an District, Guangdong Province in summer in June, with a growth period of about 125-145 days, and entering the flowering and fruiting period in mid-to-late July. Seedlings are raised in seedling trays, transplanted when there are 3-4 true leaves, and one tree is planted in each pot. 15-15-15 water-soluble fertilizer is applied as base fertilizer and in the seedling stage. The water-soluble fertilizers for promoting tomato color change of Examples 1-3 and Comparative Example 1 are respectively used, and 25 kg per mu is used for fertilization each time, and fertilization is applied 4 times in total in the flowering and fruiting period, the young fruit period, the fruit expansion period, and the harvest period. Each fertilization is carried out by drip irrigation, and the fertilizer-water ratio is 1:600. The experiment was placed outside the experimental platform, with an average daytime temperature of 33-36°C, and a maximum temperature of 37°C. There were no shade nets or other shelters, and attention was paid to avoiding rain. Watering was carried out in the morning and evening according to the dryness and wetness of the soil. The tomatoes were picked after they were ripe. After the experiment was completed, the number of results, fruit color change rate, total fresh weight of the aboveground part, and vitamin C content, fruit cracking rate, deformity rate, soluble sugar content and soluble protein content of each treatment were measured. The test of vitamin C, soluble sugar content and soluble protein content was based on the standard 2,6-dichlorophenol indophenol method, anthrone method and Coomassie brilliant blue colorimetric method. The deformity rate = number of deformed fruits × 100% / total number of results, the fruit cracking rate = number of cracked fruits × 100% / total number of results, and the fruit color change rate = uniform color change number × 100% / total number of results.

[0063] The experiment was repeated three times, and the aboveground fresh weight, vitamin C, fruit cracking rate, deformity rate, soluble sugar content and soluble protein content of tomatoes obtained from the five experiments were tested and averaged. The results are shown in Tables 1-4 and Figure 3-Figure 5 shown.

[0064] Table 1. Tomato single fruit weight and yield test

[0065]

[0066] Table 2 Tomato special color rate test

[0067] deal with Total number Uniform number of color changes Color change rate Example 1 62 55 88.71 Example 2 69 58 84.06 Example 3 57 49 85.97 Comparative Example 1 52 35 67.31

[0068] Table 3. Tomato fruit deformity rate and fruit cracking rate test

[0069]

[0070] Table 4. Vitamin C content and soluble sugar content test of tomatoes

[0071]

[0072] In the tomato planting experiment, Figure 3It can be seen that the tomato fruits of Example 1 and Example 2 have uniform and bright color change, and the fruit sizes are similar, while the fruits of Example 3 and the comparative example are smaller. Combining Table 1 and Table 2, it can be seen that Example 1 and Example 2 both show significant positive effects in increasing single fruit weight, total yield and color change rate, especially Example 2, which has the highest increase percentages of single fruit weight and total yield, reaching 24.80% and 28.25% respectively. Figure 4 and Figure 5 As shown in Table 3, the fruits of Example 1 and Example 2 have regular shapes and intact surfaces, while the fruits of Example 3 and Comparative Example 1 have irregular shapes and are partially damaged and cracked. In combination with Table 3, Example 1 and Example 2 are also superior to Comparative Example 1 in reducing the deformed fruit rate and the cracked fruit rate. Although the reduction in the deformed fruit rate and the cracked fruit rate of Example 3 is not as significant as that of Example 1 and Example 2, it is still superior to Comparative Example 1. In combination with Table 4, it can be seen that in terms of nutritional components, the vitamin C content and soluble sugar content of Example 1 and Example 2 are also improved, among which the soluble sugar content of Example 2 increases most significantly, reaching 11.51%. These results show that the yield, quality and nutritional value of tomatoes can be effectively improved through appropriate treatment methods.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A water-soluble fertilizer for promoting tomato color change, characterized in that: The invention comprises the following raw materials in parts by weight: 15-25 parts of nitrogen source raw materials, 10-25 parts of phosphorus source raw materials, 45-65 parts of potassium source raw materials, 1-2 parts of magnesium source raw materials and 0.1-0.5 parts of astaxanthin.

2. A water-soluble fertilizer for promoting tomato color change according to claim 1, characterized in that: The nitrogen source raw material is at least one of urea, ammonium sulfate and ammonium bicarbonate; the phosphorus source raw material is at least one of industrial monoammonium, ammonium polyphosphate and nitrophosphate compound fertilizer; the potassium source raw material is at least one of potassium sulfate, potassium carbonate and potassium chloride; the magnesium source raw material is at least one of magnesium sulfate, magnesium nitrate and magnesium chloride.

3. A method for preparing astaxanthin for preparing a water-soluble fertilizer for promoting tomato color change as claimed in claim 1 or 2, characterized in that: The steps include: inoculating deep red yeast in a prepared first fermentation medium for culturing and screening, inoculating deep red yeast screened by the first fermentation medium in a prepared second fermentation medium for fermentation, centrifuging the fermentation liquid after the fermentation is completed, taking the supernatant after centrifugation, evaporating and concentrating, adding dimethyl sulfoxide and ethanol for extraction, and finally drying and concentrating to constant weight to prepare the product.

4. The method for preparing astaxanthin for preparing a water-soluble fertilizer for promoting tomato color change according to claim 3, characterized in that: The first fermentation medium comprises 20-25 g / L glucose, 10-15 g / L beef peptone, 5.5-6 g / L yeast extract, 8.5-10 g / L sodium chloride, 1.5-2 g / L magnesium sulfate and 5-6 g / L dipotassium hydrogen phosphate, which are mixed evenly, the pH is adjusted to 4.5-5, and sterilized; The second fermentation medium includes 20-25 g / L glucose, 10-15 g / L beef peptone, 15-20 g / L yeast extract, 8.5-10 g / L sodium chloride, 0.1-0.2 g / L magnesium sulfate, 0.15-0.2 g / L potassium hydrogen phosphate, and 0.65-1 g / L Tween, which are mixed evenly, adjusted to pH 4.5-5, and sterilized.

5. The method for preparing astaxanthin for preparing a water-soluble fertilizer for promoting tomato color change according to claim 3, characterized in that: The fermentation is carried out by inoculating 4-6% red yeast and culturing at 24-28° C. for 3-4 days.

6. The method for preparing astaxanthin for preparing a water-soluble fertilizer for promoting tomato color change according to claim 3, characterized in that: The mass ratio of the dimethyl sulfoxide to the ethanol is 2.7-3:1.8-2, and the pH value of the extraction is 5.5-6.

0.

7. The method for preparing astaxanthin for preparing a water-soluble fertilizer for promoting tomato color change according to claim 3, characterized in that: The evaporation concentration is carried out by using a rotary evaporator at 40-45 rpm and 40-45°C.

8. The method for preparing astaxanthin for preparing a water-soluble fertilizer for promoting tomato color change according to claim 3, characterized in that: The drying and concentration is carried out in a nitrogen generator.

9. A method for preparing a water-soluble fertilizer for promoting tomato color change according to claim 1 or 2, characterized in that: The steps include: heating and melting a nitrogen source, then passing it into a primary mixing tank, and adding a potassium source into the primary mixing tank; passing the molten mixture in the primary mixing tank into a secondary mixing tank, and adding a phosphorus source and a magnesium source into the secondary mixing tank; passing the molten mixture in the secondary mixing tank into a granulating device for granulation, and finally cooling and solidifying to obtain a granular compound fertilizer; dissolving astaxanthin with anti-caking oil and uniformly spraying it on the surface of the compound fertilizer to prepare a water-soluble fertilizer that promotes tomato color change.

10. The method for preparing a water-soluble fertilizer for promoting tomato color change according to claim 9, characterized in that: The granulation method is any one of high tower granulation, drum fluidized bed granulation, disc granulation and spray granulation.

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