Selenium-rich foliar fertilizer for pitaya and preparation method of selenium-rich foliar fertilizer

Abstract

The invention discloses a selenium-rich foliar fertilizer for pitaya and a preparation method thereof, and belongs to the technical field of pitaya planting.By means of the selenium-rich foliar fertilizer for the pitaya, common pitaya can be converted into selenium-rich functional fruits with high added value, and the selenium-rich foliar fertilizer is accurately applied in key periods of 3 days, 13 days and 25 days after flowering and pollination, so that the yield of the pitaya is increased, and the yield of the pitaya is increased. The selenium element accumulation and fruit weight gain effects are maximized, and meanwhile, the selenium element is quickly transferred to the fruits after being absorbed by leaves by targeted spraying on the fruits and branches, so that the bioavailability of selenium is improved; the foliage application mode avoids excessive accumulation of selenium in soil, prevents the risk of soil selenium pollution, promotes the development of ecological agriculture, solves the problem of lack of special selenium-rich fertilizer for pitaya compared with the prior art, realizes synchronous improvement of nutritional quality and yield, and is suitable for large-scale popularization and application. The key technical support is provided for the development of the high-quality functional dragon fruit industry.

Description

Technical Field

[0001] The invention relates to the technical field of pitaya planting, and in particular to a selenium-rich foliar fertilizer for pitaya and a preparation method thereof. Background Art

[0002] The main source of selenium intake by the human body is food, especially plant-based food. Low selenium content and effectiveness in the soil, which leads to low selenium content in plants, is the main cause of selenium deficiency in humans or animals. Applying selenium-containing fertilizers is a common method used to produce selenium-rich crops. In terms of applying selenium-containing fertilizers, the three most common methods are soil application, seed mixing, and foliar spraying. Among them, seed mixing is difficult to master and is therefore less used in production; soil application of selenium is costly, and selenium easily reacts with soil components; foliar spraying is gradually becoming the mainstream selenium enrichment technology due to its high absorption efficiency, small dosage, and quick effect.

[0003] Red-fleshed pitaya is a perennial, evergreen vine-bearing berry tree with edible flowers, stems, and fruit, boasting high medicinal value. The introduced pitaya exhibits rapid growth, early fruiting, and high yields. It tolerates heat and drought, but is vulnerable to cold, and is highly disease-resistant. Its white flowers and red fruit are highly valuable for both medicinal and edible uses, making it ideal for ornamental potting or field production, making it a high-quality variety for tourism agriculture.

[0004] Chinese patent document CN117466679A discloses a pitaya fruit weight-increasing foliar fertilizer and its application method. The pitaya fruit weight-increasing foliar fertilizer is a liquid fertilizer comprising the following components by weight: 1.5-2.5 mg / L of S-inducible, 0.03-0.04 mg / L of 1,4-hydroxybrassinosteroid, 0.008-0.012 g / L of forchlorfenuron, 0.001-0.0015 g / L of diethylaminoethyl hexanoate, 0.2-0.3 g / L of amino acids, 0.5-1 g / L of chelated zinc, 0.5-1 g / L of chelated copper, 1-2 g / L of urea, and 0.5-1 g / L of calcium ammonium nitrate. When the pitaya fruit is in its fruit expansion phase, the foliar fertilizer is sprayed on the fruit and stems at night 12-14 days and / or 22-24 days after pollination, until the fruit surface is evenly covered with droplets. After treatment, the average single fruit weight increased significantly compared to before treatment, with a 22% increase in fruit weight, demonstrating a good weight-increasing effect. This patent focuses solely on the weight-increasing function of pitaya fruit, lacking nutritional enhancement, and failing to meet current consumer demand for functional agricultural products. While this technical solution can achieve a 22% increase in fruit weight, it does not involve the enrichment of functional nutrients such as selenium, and is unable to transform ordinary pitaya into a high-value-added selenium-rich functional fruit, limiting the product's market competitiveness and economic benefits. Summary of the Invention

[0005] The main purpose of the present invention is to provide a selenium-rich foliar fertilizer for pitaya and a preparation method thereof. By applying the selenium-rich foliar fertilizer for pitaya on the surface of pitaya fruit and branches, ordinary pitaya can be converted into a high-value-added selenium-rich functional fruit. This not only solves the problem of lack of special selenium-rich fertilizer for pitaya, but also achieves a simultaneous improvement in nutritional quality and yield, providing key technical support for the development of a high-quality functional pitaya industry. To achieve the above objectives, the present invention provides a selenium-rich foliar fertilizer for pitaya, comprising the following components: 1.5-2.5 mg / L S-inducer, 5-8 g / L sodium selenite, 2.2-2.8 g / L biochemical potassium humate, 30-50 g / L dipotassium hydrogen phosphate, 20-40 g / L urea, and 10-20 g / L synergist.

[0006] Preferably, the selenium-rich foliar fertilizer for pitaya comprises the following components: 1.8-2.2 mg / L S-absorbent, 5-7 g / L sodium selenite, 2.4-2.6 g / L biochemical potassium humate, 35-45 g / L dipotassium hydrogen phosphate, 25-35 g / L urea, and 14-18 g / L synergist.

[0007] The S-inducing agent in the selenium-enriched foliar fertilizer of the present invention has the effects of regulating plant growth and enhancing stress resistance, can improve the disease resistance of pitaya seedlings and promote nutrient absorption; biochemical potassium fulvate has a growth-promoting factor with high biological activity function, has good stability, strong comprehensive ability, and can improve the absorption and utilization of trace elements by plants; the synergist can chelate with sodium selenite to promote the absorption of selenium by pitaya leaves and fruits, and can also effectively reduce the content of heavy metals such as lead and cadmium in crops, thereby improving the stress resistance of crops. The present invention uses sodium selenite, biochemical potassium fulvate, and the synergist in combination to promote the absorption of selenium by plants, effectively degrade the content of heavy metals, and has the effects of regulating pitaya growth and enhancing the stress resistance of pitaya seedlings.

[0008] Preferably, the preparation method of the synergist is as follows: (1) Dispersing microcrystalline cellulose powder in dimethyl sulfoxide, adding glutaric anhydride, heating to react, adding ice water after the reaction is completed to precipitate the product, centrifuging and freeze-drying to obtain carboxylated cellulose; (2) Resveratrol is added to dimethyl sulfoxide, stirred to dissolve, carboxylated cellulose and p-toluenesulfonic acid are added, and the temperature is raised to react. After the reaction is completed, the solvent is evaporated under reduced pressure, the solid is collected, washed and dried, and then added to N,N-dimethylformamide, castor oil maleate and ammonium persulfate are added, and the reaction is stirred. After the reaction is completed, the solvent is evaporated under reduced pressure, and the residue is collected, washed and dried to obtain the enhancer.

[0009] Preferably, in step (1), the mass ratio of microcrystalline cellulose to glutaric anhydride is 8-12:1; the heating reaction temperature is 50-80° C., and the heating time is 6-8 h.

[0010] Preferably, in step (2), the mass ratio of resveratrol, carboxylated cellulose, and castor oil maleate is 3-5:10-15:8-20; the temperature of the heating reaction is 80-120°C, and the reaction time is 5-8h; the temperature of the stirring reaction is 60-80°C, and the reaction time is 4-6h.

[0011] By adding synergists, the adhesion and spreadability of foliar fertilizers on pitaya leaves can be significantly improved, the splashing during foliar fertilizer spraying can be reduced, the foliar fertilizer is more evenly distributed on the leaf surface, and the wetting and spreading area of the droplets after spraying is increased, thereby improving the utilization rate of foliar fertilizers and forming a three-dimensional network structure. This three-dimensional network can adsorb active ingredients such as selenium, reduce the loss caused by wind or gravity, and improve the accumulation efficiency of selenium in the leaves; moreover, the excess polar groups in resveratrol can not only form hydrogen bonds with water molecules, reduce the surface tension of the fertilizer, enhance its affinity with the leaves, and achieve the effect of rapid absorption, but also by introducing castor oil maleate, its long hydrophobic chain can emulsify lipid dirt on the leaf surface, and can also enhance the respiration of the leaves, promote the penetration of fertilizer solution into the wax layer, accelerate the transport of selenium to the stomata and mesophyll cells, and thus promote the growth of pitaya.

[0012] The present invention also discloses a method for preparing the selenium-rich foliar fertilizer for pitaya, comprising the following steps: Weigh S-inducible, sodium selenite, biochemical potassium humate, dipotassium hydrogen phosphate, urea, and a synergist, add them into water, mix and stir evenly to obtain a selenium-rich foliar fertilizer for pitaya.

[0013] The present invention also discloses the application of the selenium-rich foliar fertilizer for pitaya, which is specifically sprayed on the fruit and branches 3 days, 13 days and 25 days after flowering and pollination, until the surface of the pitaya fruit and branches are evenly covered with droplets. In case of rain, it is necessary to spray again when the weather clears up.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1) Using the selenium-rich foliar fertilizer for pitaya obtained in this application, ordinary pitaya can be converted into high-value-added selenium-rich functional fruit. It is accurately applied at the critical periods of 3d, 13d and 25d after flowering and pollination to maximize selenium accumulation and fruit weight gain effects. At the same time, targeted spraying of fruits and branches ensures that selenium is absorbed by leaves and quickly transported to fruits, thereby improving the bioavailability of selenium; the foliar application method avoids excessive accumulation of selenium in the soil, prevents the risk of soil selenium pollution, and promotes the development of ecological agriculture. Compared with the existing technology, it not only solves the problem of lack of special selenium-rich fertilizers for pitaya, but also achieves the simultaneous improvement of nutritional quality and yield, providing key technical support for the development of high-quality functional pitaya industry; 2) The preparation of the synergist of the present invention first involves carboxylating microcrystalline cellulose, then reacting resveratrol with the carboxyl group and grafting it onto the microcrystalline cellulose to provide a carbon-carbon double bond for subsequent reactions, and finally reacting castor oil maleate with the carbon-carbon double bond to introduce castor oil maleate onto the microcrystalline cellulose to obtain a stable composite structure with microcrystalline cellulose as a skeleton. The composite structure can significantly reduce the surface tension of the aqueous solution, improve the adhesion and spreadability on the wax layer of pitaya leaves, reduce splashing during foliar fertilizer spraying, thereby improving the utilization rate of the foliar fertilizer, and form a three-dimensional network structure. The three-dimensional network The complex can absorb active ingredients such as selenium, reduce the loss caused by wind or gravity, and improve the accumulation efficiency of selenium in the leaves; at the same time, the excess polar groups in resveratrol can not only form hydrogen bonds with water molecules, reduce the surface tension of the fertilizer, enhance its affinity with the leaves, and achieve the effect of rapid absorption, but also through the accession of castor oil maleate, its long hydrophobic chain can emulsify lipid dirt on the leaf surface, and also enhance the respiration of the leaves, promote the penetration of fertilizer liquid into the wax layer, accelerate the transport of selenium to the stomata and mesophyll cells, make it less likely to be washed away by rainwater, achieve a long-term cleaning effect, and thus promote the growth of pitaya. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a transmission electron microscope image of the synergist prepared in Example 1 of the present invention.

[0017] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0018] To avoid redundancy, the items used in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0019] Example 1 A method for preparing selenium-rich foliar fertilizer for pitaya comprises the following steps: Weigh 2 mg of S-absorbent, 6.8 g of sodium selenite, 2.4 g of biochemical potassium humate, 40 g of dipotassium hydrogen phosphate, 30 g of urea, and 15 g of synergist, mix them evenly, add them into water, mix and stir evenly, add water to make the volume to 1 L, and obtain selenium-rich foliar fertilizer for pitaya.

[0020] The preparation method of the synergist comprises the following steps: (1) Disperse 20 g of microcrystalline cellulose powder in 300 mL of dimethyl sulfoxide, add 2 g of glutaric anhydride, and then heat at 70 °C for 7 h. After the reaction is complete, add 50 mL of ice water to precipitate the product. After centrifugation, collect the solid, wash it, and freeze-dry it to obtain carboxylated cellulose. (2) 4.3 g of resveratrol was added to 200 mL of dimethyl sulfoxide, stirred to dissolve, 12.6 g of carboxylated cellulose and 1 g of p-toluenesulfonic acid were added, and the temperature was raised to 100 ° C for 6 h. After the reaction was completed, the solvent was evaporated under reduced pressure, the solid was collected, washed and dried, and then added to 200 mL of N, N-dimethylformamide, 15 g of castor oil maleate and 0.8 g of ammonium persulfate were added, and the reaction was stirred at 70 ° C for 5 h. After the reaction was completed, the solvent was evaporated under reduced pressure, and the residue was collected, washed and dried to obtain the enhancer.

[0021] The transmission electron microscope image of the synergist prepared in this example is as follows: Figure 1 As shown in the figure, it can be seen that the components of the synergist are interconnected and present a three-dimensional network morphology.

[0022] Example 2 A method for preparing selenium-rich foliar fertilizer for pitaya comprises the following steps: Weigh 1.5 mg of S-inducible, 5 g of sodium selenite, 2.2 g of biochemical potassium humate, 30 g of dipotassium hydrogen phosphate, 20 g of urea, and 10 g of synergist, mix them evenly, add them into water, mix and stir evenly, add water to make the volume to 1 L, and obtain selenium-rich foliar fertilizer for pitaya.

[0023] The preparation method of the synergist comprises the following steps: (1) Disperse 16 g of microcrystalline cellulose powder in 300 mL of dimethyl sulfoxide, add 2 g of glutaric anhydride, and then heat at 70 °C for 7 h. After the reaction is complete, add 50 mL of ice water to precipitate the product. After centrifugation, collect the solid, wash it, and freeze-dry it to obtain carboxylated cellulose. (2) 3 g of resveratrol was added to 200 mL of dimethyl sulfoxide, stirred to dissolve, 10 g of carboxylated cellulose and 1 g of p-toluenesulfonic acid were added, and the temperature was raised to 120°C for reaction for 5 h. After the reaction was completed, the solvent was evaporated under reduced pressure, the solid was collected, washed and dried, and then added to 200 mL of N,N-dimethylformamide, 8 g of castor oil maleate and 0.8 g of ammonium persulfate were added, and the reaction was stirred at 60°C for 6 h. After the reaction was completed, the solvent was evaporated under reduced pressure, and the residue was collected, washed and dried to obtain the enhancer.

[0024] Example 3 A method for preparing selenium-rich foliar fertilizer for pitaya comprises the following steps: Weigh 2.5 mg of S-inducible, 8 g of sodium selenite, 2.8 g of biochemical potassium humate, 50 g of dipotassium hydrogen phosphate, 40 g of urea, and 20 g of synergist, mix them evenly, add them into water, mix and stir evenly, add water to make the volume to 1 L, and obtain selenium-rich foliar fertilizer for pitaya.

[0025] The preparation method of the synergist comprises the following steps: (1) Disperse 24 g of microcrystalline cellulose powder in 300 mL of dimethyl sulfoxide, add 2 g of glutaric anhydride, and then heat at 80 °C for 6 h. After the reaction is complete, add 80 mL of ice water to precipitate the product. After centrifugation, collect the solid, wash it, and freeze-dry it to obtain carboxylated cellulose. (2) 5 g of resveratrol was added to 200 mL of dimethyl sulfoxide, stirred to dissolve, 15 g of carboxylated cellulose and 1.2 g of p-toluenesulfonic acid were added, and the temperature was raised to 80°C for reaction for 8 h. After the reaction was completed, the solvent was evaporated under reduced pressure, the solid was collected, washed and dried, and then added to 200 mL of N,N-dimethylformamide. 20 g of castor oil maleate and 1.3 g of ammonium persulfate were added, and the reaction was stirred at 80°C for 4 h. After the reaction was completed, the solvent was evaporated under reduced pressure, and the residue was collected, washed and dried to obtain the enhancer.

[0026] Comparative Example 1 A method for preparing selenium-rich foliar fertilizer for pitaya comprises the following steps: Weigh 2 mg of S-absorbent, 6.8 g of sodium selenite, 2.4 g of biochemical potassium humate, 40 g of dipotassium hydrogen phosphate, 30 g of urea, and 15 g of synergist, mix them evenly, add them into water, mix and stir evenly, add water to make the volume to 1 L, and obtain selenium-rich foliar fertilizer for pitaya.

[0027] The preparation method of the synergist is similar to that of Example 1, except that castor oil maleate is not added, and specifically comprises the following steps: (1) Disperse 20 g of microcrystalline cellulose powder in 300 mL of dimethyl sulfoxide, add 2 g of glutaric anhydride, and then heat at 70 °C for 7 h. After the reaction is complete, add 50 mL of ice water to precipitate the product. After centrifugation, collect the solid, wash it, and freeze-dry it to obtain carboxylated cellulose. (2) 4.3 g of resveratrol was added to 200 mL of dimethyl sulfoxide and stirred to dissolve it. 12.6 g of carboxylated cellulose and 1 g of p-toluenesulfonic acid were added and the temperature was raised to 100° C. to react for 6 h. After the reaction was completed, the solvent was evaporated under reduced pressure, the solid was collected, washed and dried, and the residue was collected, washed and dried to obtain the synergist.

[0028] Comparative Example 2 A method for preparing selenium-rich foliar fertilizer for pitaya comprises the following steps: Weigh 2 mg of S-absorbent, 6.8 g of sodium selenite, 2.4 g of biochemical potassium humate, 40 g of dipotassium hydrogen phosphate, 30 g of urea, and 15 g of synergist, mix them evenly, add them into water, mix and stir evenly, add water to make the volume to 1 L, and obtain selenium-rich foliar fertilizer for pitaya.

[0029] The preparation method of the synergist comprises the following steps: 4.3 g of resveratrol was added to 200 mL of N,N-dimethylformamide, and 15 g of castor oil maleate and 0.8 g of ammonium persulfate were added, and the mixture was stirred at 70° C. for 5 h. After the reaction was completed, the solvent was evaporated under reduced pressure, and the residue was collected, washed, and dried to obtain the synergist.

[0030] Comparative Example 3 A method for preparing selenium-rich foliar fertilizer for pitaya comprises the following steps: Weigh 2 mg of S-absorbent, 6.8 g of sodium selenite, 2.4 g of biochemical potassium humate, 40 g of dipotassium hydrogen phosphate, 30 g of urea, and 15 g of synergist, mix them evenly, add them into water, mix and stir evenly, add water to make the volume to 1 L, and obtain selenium-rich foliar fertilizer for pitaya.

[0031] The synergist is a mixture of 4.3g resveratrol, 12.6g microcrystalline cellulose, and 15g castor oil maleate.

[0032] Comparative Example 4 A method for preparing selenium-rich foliar fertilizer for pitaya comprises the following steps: Weigh 2 mg of S-antibiotic, 6.8 g of sodium selenite, 2.4 g of biochemical potassium humate, 40 g of dipotassium hydrogen phosphate, and 30 g of urea, mix them evenly, add them into water and stir them evenly, add water to make the volume to 1 L, and obtain selenium-rich foliar fertilizer for pitaya.

[0033] Application Examples The selenium-enriched foliar fertilizer obtained in Examples 1-3 and Comparative Examples 1-4 was sprayed on the pitaya fruits and stems at night (after sunset, when the stomata on the pitaya skin open) 3, 13, and 25 days after the pitaya flowers and pollination (the sprayed areas were evenly covered with droplets). In case of rain, re-spraying was required when the weather cleared. The experimental field was divided into three test plots, each measuring 15 m × 10 m, and each test plot measuring 4 m × 2.7 m. ≥30 fruits were sprayed. After the fruits matured, the average weight of 10 pitaya fruits in each plot was randomly calculated. The selenium content in the pitaya pulp was determined by drying the pitaya pulp and then measuring it using atomic fluorescence spectrometry. The results are shown in Table 1.

[0034] Table 1 Effects of different fertilizer treatments on pitaya pulp and yield Selenium content in pulp (mg / kg) Average single fruit weight (g) Example 1 0.0203±0.0006b 385.3±51.2a Example 2 0.0195±0.0003b 380.5±36.2a Example 3 0.0199±0.0004b 391.2±25.1a Comparative Example 1 0.0123±0.0012c 346.1±31.5b Comparative Example 2 0.0102±0.0007c 328.6±23.7b Comparative Example 3 0.0094±0.0009c 313.7±18.9c Comparative Example 4 0.0035±0.0008a 300.2±28.8c Note: Different letters in the table indicate significant differences in statistical tests; if the same letters are marked, the differences are not significant.

[0035] It can be seen from the experimental results in Table 1 that the selenium-rich foliar fertilizer for pitaya obtained by the present invention can well promote the absorption and utilization of selenium by pitaya, and at the same time promote the growth of pitaya fruit.

[0036] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of the present invention.

Claims

1. A selenium-rich foliar fertilizer for pitaya, characterized in that: The invention comprises the following components: 1.5-2.5 mg / L S-inducible, 5-8 g / L sodium selenite, 2.2-2.8 g / L biochemical potassium fulvic acid, 30-50 g / L dipotassium hydrogen phosphate, 20-40 g / L urea and 10-20 g / L synergist.

2. Foliar fertilizer according to claim 1, is characterized in that, The invention comprises the following components: 1.8-2.2 mg / L S-antibiotic, 5-7 g / L sodium selenite, 2.4-2.6 g / L biochemical potassium fulvic acid, 35-45 g / L dipotassium hydrogen phosphate, 25-35 g / L urea and 14-18 g / L synergist.

3. Foliar fertilizer according to claim 1, is characterized in that, The preparation method of the synergist is as follows: (1) Dispersing microcrystalline cellulose powder in dimethyl sulfoxide, adding glutaric anhydride, heating to react, adding ice water after the reaction is completed to precipitate the product, centrifuging and freeze-drying to obtain carboxylated cellulose; (2) Resveratrol is added to dimethyl sulfoxide, stirred to dissolve, carboxylated cellulose and p-toluenesulfonic acid are added, and the temperature is raised to react. After the reaction is completed, the solvent is evaporated under reduced pressure, the solid is collected, washed and dried, and then added to N,N-dimethylformamide, castor oil maleate and ammonium persulfate are added, and the reaction is stirred. After the reaction is completed, the solvent is evaporated under reduced pressure, and the residue is collected, washed and dried to obtain the enhancer.

4. Foliar fertilizer according to claim 3, is characterized in that: In the step (1), the mass ratio of microcrystalline cellulose to glutaric anhydride is 8-12:

1.

5. Foliar fertilizer according to claim 3, is characterized in that: In the step (1), the heating reaction temperature is 50-80° C. and the heating time is 6-8 h.

6. Foliar fertilizer according to claim 3, is characterized in that: In the step (2), the mass ratio of resveratrol, carboxylated cellulose, and castor oil maleate is 3-5:10-15:8-20.

7. Foliar fertilizer according to claim 3, is characterized in that, The temperature of the heating reaction in step (2) is 80-120° C., and the reaction time is 5-8 hours.

8. Foliar fertilizer according to claim 3, is characterized in that, The stirring reaction temperature in step (2) is 60-80°C, and the reaction time is 4-6 hours.

9. A method for preparing the foliar fertilizer according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: weighing S-absorbent, sodium selenite, biochemical potassium fulvic acid, dipotassium hydrogen phosphate, urea and a synergist, adding the mixture into water, and mixing and stirring evenly to obtain selenium-rich foliar fertilizer for pitaya.

10. An application of the foliar fertilizer according to any one of claims 1 to 8, characterized in that: Spray the fruits and branches 3d, 13d and 25d after flowering and pollination, until the surface of the dragon fruit fruits and branches are evenly covered with droplets. If it rains, spray again when the weather clears up.

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