High-calcium foliar fertilizer capable of enhancing salt and alkali tolerance of crops, and preparation method and application thereof

Abstract

The application provides a high-calcium foliar fertilizer capable of enhancing salt and alkali tolerance of crops, and a preparation method and application thereof, and belongs to the technical field of crop planting. The high-calcium foliar fertilizer takes citric acid fermentation tail liquid, inorganic chemical fertilizer and anhydrous calcium chloride as raw materials, and comprises the following effective components: organic matter of 0.4 g / L or more, N of 0.2 g / L or more, P2O5 of 0.12 g / L or more, K2O of 0.08 g / L or more, and 0.25% to 2.0% of anhydrous calcium chloride. The raw material components in the high-calcium foliar fertilizer are mutually matched and synergistically enhanced, and jointly play a role in significantly enhancing the salt and alkali tolerance of crops, and have remarkable application effects in improving the biomass of crops, promoting the growth of crops, improving the photosynthetic capacity, resisting active oxygen damage, and expelling salt base ions. In addition, the application is also of great significance in solving environmental pollution, recycling waste liquid, reducing the production cost of fertilizers, and developing green and healthy agriculture.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of crop planting, and particularly relates to a high-calcium foliar fertilizer capable of enhancing the salt and alkali tolerance of crops, and a preparation method and application thereof. BACKGROUND

[0002] Soil salinization is an important environmental problem affecting crop growth and limiting the sustainable development of agriculture and animal husbandry. Salt stress can cause ion stress, osmotic stress and oxidative damage in plants, leading to blocked metabolism, ion imbalance in cells, and affected synthesis of photosynthetic pigments, protein content, lipid content, antioxidant enzyme activity and antioxidant content. Limited plant growth is the most obvious phenomenon caused by salt and alkali stress, and slow plant development further inhibits plant differentiation function and establishment of various organs, and advances the original development process of plants. During plant growth, photosynthesis and physiological metabolism of plants are affected by salt stress, leading to metabolic disorder during plant growth period, and appearance of plant wilting or death.

[0003] Salinization is widely distributed in more than 100 countries and regions in the world, and 50% of the irrigation areas are at risk of salinization or potential salinization. The problem of salinization in China ranks third in the world. There are about 550 million mu of various types of available saline-alkali land resources in China, of which 185 million mu of saline-alkali land has agricultural utilization prospects, accounting for only 33.6% of the available saline-alkali land. The development of new products for improving the salt and alkali tolerance of crops is one of the inevitable conditions for the development of modern agriculture.

[0004] Excessive application of chemical fertilizers is one of the important reasons for soil salinization. The application of organic liquid fertilizer together with chemical fertilizer can reduce the negative effects caused by excessive application of chemical fertilizer, and the application of organic liquid fertilizer together with chemical fertilizer in the form of water drop or foliar spraying can further promote the absorption and utilization of nitrogen, phosphorus and potassium nutrients by plants, thereby improving the yield and quality of crops. Therefore, the new crop foliar fertilizer product needs to consider the problem of application of organic liquid fertilizer together with inorganic fertilizer as raw materials.

[0005] With the rapid development of agricultural production and rapid development of land resources, the problem of soil salinization is becoming more and more serious, and people's demand for strengthening the improvement of salinization is getting higher and higher. In order to improve the salt tolerance of plants and help plants better adapt to salt environment, many scholars have carried out research on the effects of exogenous substances on the salt and alkali tolerance of plants and the mechanism of action. There are more than 50 kinds of exogenous substances reported. According to the properties of exogenous substances or their use methods, they can be divided into five categories: sugars, antioxidant substances non-enzymes, plant growth substances, signal molecules and polyols.

[0006] Ca 2+ As a signal molecule, Ca 2+ Effect of mixed inorganic fertilizer with citric acid fermentation tail liquid of industrial waste on plant salt and alkali stress. SUMMARY

[0007] In order to solve the above technical problems, the present application provides a high calcium foliar fertilizer capable of enhancing the salt and alkali tolerance of crops, and a preparation method and application thereof. The high calcium foliar fertilizer takes citric acid fermentation tail liquid, inorganic chemical fertilizer and anhydrous calcium chloride as raw materials, and comprises the following concentrations of effective components: ≥0.4 g / L of organic matter, ≥0.2 g / L of N, ≥0.12 g / L of P2O5, ≥0.08 g / L of K2O and 0.25% to 2.0% of anhydrous calcium chloride. The raw material components of the high calcium foliar fertilizer cooperate with each other and have synergistic effect, and jointly play a role in significantly enhancing the salt and alkali tolerance of crops. The application effect is remarkable in improving the biomass of crops, promoting the growth of crops, improving the photosynthetic capacity, resisting active oxygen damage and the ability to expel salt base ions, etc. In addition, the present application is also of great significance in solving environmental pollution, recycling waste liquid, reducing the production cost of fertilizer and developing green and healthy agriculture.

[0008] In order to achieve the above purpose, the present application adopts the following technical solutions:

[0009] The present application provides a high calcium foliar fertilizer capable of enhancing the salt and alkali tolerance of crops, which takes citric acid fermentation tail liquid, inorganic chemical fertilizer and anhydrous calcium chloride as raw materials, and comprises the following concentrations of effective components: ≥0.4 g / L of organic matter, ≥0.2 g / L of N, ≥0.12 g / L of P2O5, ≥0.08 g / L of K2O and 0.25% to 2.0% of anhydrous calcium chloride. The main component composition of the citric acid fermentation tail liquid is: organic matter ≥220 g / L, pH (1:250) = 4.2 to 6.2, N = 8 to 12 g / L, K2O = 16 to 20 g / L, amino acid = 8.5 to 9.5 g / L, total sugar = 75 to 85 g / L, and peptide = 35 to 40 g / L. The inorganic chemical fertilizer is urea, potassium sulfate and water-soluble monoammonium phosphate. The N content in the urea is ≥46.0%, the K2O content in the potassium sulfate is ≥51%, and the P2O5 content in the water-soluble monoammonium phosphate is ≥73%.

[0010] The present application also provides a preparation method of the high calcium foliar fertilizer, comprising the following steps:

[0011] (1) taking the citric acid fermentation tail liquid as a mother liquor; (2) mixing the mother liquor with the inorganic chemical fertilizer according to a ratio of mother liquor: urea: water-soluble monoammonium phosphate: potassium sulfate = (950-1050): (190-200): (80-85): (40-45); (3) determining the nutrient content of the obtained mixture after the mixing, so that the organic matter content is greater than or equal to 220 g / L, the N content is greater than or equal to 100 g / L, the P2O5 content is greater than or equal to 60 g / L, and the K2O content is greater than or equal to 40 g / L, to obtain a liquid fertilizer, and the liquid fertilizer is diluted by a corresponding multiple; and (4) mixing the diluted liquid fertilizer with anhydrous calcium chloride, so that the anhydrous calcium chloride content is 0.25-2.0%, and adjusting the pH to 6.5-7.5, to obtain the high-calcium foliar fertilizer.

[0012] The mother liquor of step (1) contains starch, protein, fermentation residues, glucose, ammonia nitrogen and fat and other organic matters.

[0013] Further, the mixing ratio of the mother liquor and the inorganic chemical fertilizer in step (2) is mother liquor: urea: water-soluble monoammonium phosphate: potassium sulfate = 1000:195.7:82.2:43.2.

[0014] Further, the mixing in step (2) is performed by shaking the shaking box at 28-32℃ constant temperature for 22-26h.

[0015] Further, the mixing in step (2) is performed by shaking the shaking box at 30℃ constant temperature for 24h.

[0016] Further, the dilution multiple of the liquid fertilizer in step (3) is 450-550 times.

[0017] Further, the dilution multiple of the liquid fertilizer in step (3) is 500 times.

[0018] The mixing process in step (4) is: adding the anhydrous calcium chloride into the diluted liquid fertilizer, stirring while adding, and stopping until the liquid is uniform and lump-free.

[0019] Further, the pH is adjusted by using ammonia water in step (4).

[0020] The application also provides an application of the high-calcium foliar fertilizer in crop planting.

[0021] Further, the application time of the high-calcium foliar fertilizer in the application is the seedling stage of the crops.

[0022] Further, the application is specifically the application in the planting of salt-tolerant crops.

[0023] Compared with the prior art, the application has the following technical effects:

[0024] (1) The present application effectively solves the problem of excessive discharge of citric acid fermentation tail liquid and excessive application of chemical fertilizer to the environment, and also makes the tail liquid resourceful, turns waste into treasure, can be fully utilized, can also reduce the production cost of liquid fertilizer, and truly realizes the healthy development of green agriculture.

[0025] (2) The citric acid fermentation tail liquid disclosed by the present application is rich in a large amount of organic matter, amino acids, polypeptides and sugar substances, can promote crop nutrient absorption, improve soil fertility and improve fertilizer utilization rate; the organic matter contains rich carbon source, has a very important influence on the nutrient supply of plants, and can resist oxidative damage, improve photosynthetic characteristics and salt-tolerant ability of crops.

[0026] (3) The nitrogen, phosphorus and potassium contain a large amount of nutrient components needed by plants, and can promote the growth of plants.

[0027] (4) After the citric acid fermentation tail liquid and the chemical fertilizer are mixed, complexation, chelation or physical-chemical adsorption may occur, so as to regulate the fertilizer conversion process, improve the coincidence degree of nutrient supply and crop demand, and optimize the effect of fertilizer.

[0028] (5) The CaCl2 can improve the material accumulation amount of plants under salt stress, improve the ability of plants to resist oxidative damage, improve the Na + efflux capacity and K + / Na + in the body, improve the photosynthetic capacity and salt-tolerant ability of crops.

[0029] (6) Experiments prove that the raw material components in the high-calcium foliar fertilizer of the present application can mutually cooperate and synergistically enhance the salt-tolerant ability of crops, and the application effect is remarkable in improving the biomass of rape, promoting the growth of rape, improving the photosynthetic capacity, resisting active oxygen damage and the ability of expelling salt base ions. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The determination results of chlorophyll fluorescence parameters of rape seedlings in Example 2 of the present application;

[0031] Figure 2 The determination results of malondialdehyde content and relative permeability of leaf membrane of rape seedlings in Example 2 of the present application;

[0032] Figure 3 The determination results of Na + , K + , Ca 2+ content and K + / Na + in the body of rape seedlings in Example 2 of the present application;

[0033] Figure 4 The determination results of the rape seedling chlorophyll fluorescence parameters in Example 3 of the present application;

[0034] Figure 5 The determination results of the rape seedling leaf antioxidant enzyme activity and malondialdehyde content in Example 3 of the present application;

[0035] Figure 6 The determination results of the Na + , K + contents and K + / Na + in the rape seedling plant in Example 3 of the present application. DETAILED DESCRIPTION

[0036] The following examples are intended to illustrate the present application but not to limit the scope of the present application. Modifications or substitutions of the method, steps or conditions of the present application without departing from the spirit and essence of the present application shall fall within the scope of the present application. The present application does not have special limitation on the source of the citric acid fermentation tail liquid, and any source of the citric acid fermentation tail liquid known in the art can be used. In the present example, the citric acid fermentation tail liquid is from Jiangsu Guoxin Xielian Energy Co., Ltd. The present application does not have special limitation on the source of the inorganic chemical fertilizer, and any source of the inorganic fertilizer commonly used in the art can be used. The present application does not have special limitation on the source of the CaCl2, and any conventional analytical pure drug can be used. In the present example, the CaCl2 is from Shanghai Maikelin Biochemical Co., Ltd. In the present example, the equipment and raw materials used are commercially available unless otherwise specified, and the method used is consistent with the commonly used method unless otherwise specified.

[0037] The technical solutions of the present application will be further described in detail below in combination with examples.

[0038] Example 1

[0039] The citric acid fermentation tail liquid purchased from Jiangsu Guoxin Xielian Energy Co., Ltd. is used as the mother liquor. The mother liquor and the chemical fertilizer are mixed according to the ratio of mother liquor: urea: water-soluble monoammonium phosphate: potassium sulfate = 1000:195.7:82.2:43.2, and the obtained liquid fertilizer is subjected to oscillation in a constant temperature oscillation box at 30℃ for 24h. The nutrient substance of the liquid fertilizer is determined so that the organic matter content is ≥220g / L, the N content is ≥100g / L, the P2O5 content is ≥60g / L and the K2O content is ≥40g / L. The above liquid fertilizer is diluted 500 times, and different amounts of CaCl2 are added to the diluted liquid fertilizer to determine the pH. The pH is adjusted to 6.5-7.5 by ammonia water to obtain a high-calcium foliar fertilizer. The comprehensive content index of the fertilizer is shown in Table 1.

[0040] Table 1 quality indicators of high calcium foliar fertilizer

[0041]

[0042] Wherein:

[0043] The state of the citric acid fermentation tail liquid is liquid, the state of the inorganic chemical fertilizer (urea, potassium sulfate, monoammonium phosphate) is solid particles or powder, and the state of the anhydrous calcium chloride is powder.

[0044] The main components of the citric acid fermentation tail liquid are: organic matter ≥220 g / L, pH (1:250) = 4.2-6.2, nitrogen (N) = 10 g / L, potassium (K2O) = 18 g / L, amino acid = 8.95 g / L, total sugar = 79.4 g / L, and peptide = 37.75 g / L.

[0045] In the inorganic chemical fertilizer (urea, potassium sulfate, water-soluble monoammonium phosphate), urea (N) is ≥46.0%, potassium sulfate (K2O) is ≥51%, and water-soluble monoammonium phosphate (P2O5) is ≥73%.

[0046] Anhydrous calcium chloride (CaCl2) is ≥99.99%.

[0047] The specific method for obtaining the high calcium foliar fertilizer with different concentrations of CaCl2 is as follows:

[0048] (1) Taking 1 L of citric acid fermentation tail liquid as a mother liquor as an example, the mother liquor: urea: water-soluble monoammonium phosphate: potassium sulfate = 1000:195.7:82.2:43.2 is mixed to obtain a standby liquid fertilizer.

[0049] (2) Taking the preparation of 1 L of high calcium foliar fertilizer as an example, 2 ml of the above liquid fertilizer is taken, and the volume is made up to 1 L. The liquid fertilizer diluted 500 times above: anhydrous calcium chloride (CaCl2) = 1000:2.5 is dissolved, and a high calcium foliar fertilizer containing 0.25% CaCl2 is obtained. The liquid fertilizer diluted 500 times above: anhydrous calcium chloride (CaCl2) = 1000:5 is dissolved, and a high calcium foliar fertilizer containing 0.5% CaCl2 is obtained. The liquid fertilizer diluted 500 times above: anhydrous calcium chloride (CaCl2) = 1000:10 is dissolved, and a high calcium foliar fertilizer containing 1.0% CaCl2 is obtained. The liquid fertilizer diluted 500 times above: anhydrous calcium chloride (CaCl2) = 1000:20 is dissolved, and a high calcium foliar fertilizer containing 2.0% CaCl2 is obtained.

[0050] Example 2

[0051] Experiments were conducted on the high calcium foliar fertilizer prepared in Example 1:

[0052] The pots with same size and filled with vermiculite were selected for pot experiment, and each pot was planted with 3 rape plants, and the plants were cultured with 1 / 2 Hoagland nutrient solution, and the roots were irrigated with 200 ml of the solution every 2 days; the plants were treated after 5 leaf stage. The experiment included 6 treatments, which were: (1) CK: nutrient solution + spraying with equal amount of distilled water; (2) T1: NaHCO3 stress + spraying with equal amount of distilled water; (3) T2: NaHCO3 stress + high calcium foliar fertilizer (containing 0.25% CaCl2); (4) T3: NaHCO3 stress + high calcium foliar fertilizer (containing 0.5% CaCl2); (5) T4: NaHCO3 stress + high calcium foliar fertilizer (containing 1.0% CaCl2); (6) T5: NaHCO3 stress + high calcium foliar fertilizer (containing 2.0% CaCl2). In the above treatments, the application concentration of NaHCO3 solution was 100 mmol·L -1 The NaHCO3 solution based on Hoagland full nutrient solution was uniformly irrigated on the roots of the rape seedlings, and the irrigation amount was 2 times of the water holding capacity of vermiculite, and the deionized water was supplemented every 1 day according to the evaporation. After 4 days of stress, the high calcium foliar fertilizer was sprayed on the leaves every 3 days (the spraying time was 19:00), and the spraying standard was that water droplets just fell. Each treatment had 4 replicates, and 3 plants were determined in each replicate, and the indexes were determined after 5 times of spraying, i.e. 15 days.

[0053] Sample determination and method:

[0054] 1. Determination of rape seedling growth indexes

[0055] The rape seedlings were carefully taken out from the pots, and the vermiculite particles on the root surface were washed with clean water, and the root length and plant height of the rape seedlings were measured with a ruler, and the fresh weight of stems and leaves and the fresh weight of roots were weighed with a thousandth balance. The results are shown in Table 2.

[0056] Table 2 Effect of high calcium foliar fertilizer with different calcium content on biomass of rape seedlings

[0057]

[0058] Results Analysis: Table 2 shows that under salt-alkali stress, the biomass of rapeseed seedlings was significantly reduced. Spraying with high-calcium foliar fertilizers with different calcium contents could alleviate the effects of salt-alkali stress on rapeseed seedlings to varying degrees. Among them, the plant height and root fresh weight of both rapeseed varieties showed the most significant alleviating effect when sprayed with high-calcium foliar fertilizer containing 0.5% CaCl2. The plant height of both varieties increased by 18.55% and 21.15% respectively compared with NaHCO3 stress, and the root fresh weight increased by 70.0% and 133.3% respectively. The stem and leaf fresh weight of "Huayouza 62" and "Xiangyou 15" varieties increased significantly by 117.6% and 88.9% respectively when CaCl2 was 1.0% and 0.5% compared with NaHCO3 stress.

[0059] 2. Measurement of chlorophyll fluorescence parameters during rapeseed seedling stage

[0060] Three representative plants from each replicate were collected at the rapeseed seedling stage. Leaves with the same functional characteristics were selected, and the maximum photochemical efficiency (Fv / Fm) and potential photochemical efficiency (Fv / Fo) of chlorophyll fluorescence parameters were measured using a portable pulse-modulated fluorescence spectrometer. The results are as follows: Figure 1 As shown.

[0061] Results Analysis: Figure 1 It can be seen that, compared with the control group, the application of high-calcium foliar fertilizers with different calcium contents can improve the chlorophyll fluorescence parameters of rapeseed seedlings. Under salt-alkali stress, the potential and maximum photochemical efficiencies of "Huayouza 62" leaves increased most significantly after being sprayed with high-calcium foliar fertilizer containing 2.0% CaCl2, increasing by 8.7% and 35.6% respectively compared with salt-alkali stress. The potential and maximum photochemical efficiencies of "Xiangyou 15" stems and leaves increased most significantly after being sprayed with high-calcium foliar fertilizer containing 1.0% CaCl2, increasing by 2.6% and 19.6% respectively compared with salt-alkali stress.

[0062] 3. Determination of malondialdehyde content and relative permeability of plasma membrane in rapeseed seedling leaves

[0063] Malondialdehyde (MDA) content was determined using the thiobarbituric acid method; relative membrane permeability was expressed as relative conductivity and determined using the conductivity method. Results are as follows: Figure 2 As shown.

[0064] Results Analysis: Malondialdehyde (MDA) and relative cell membrane permeability are indicators of the degree of oxidative damage in plants. High MDA content and high relative cell membrane permeability indicate severe oxidative damage in the plant. Figure 2It can be seen that under saline-alkali stress, the content of malondialdehyde in stems and leaves of rape seedlings increased significantly, and the content of malondialdehyde in leaves of "Huayouza No. 62" decreased most obviously after spraying high-calcium foliar fertilizer containing 1.0% CaCl2, which decreased by 41.3% compared with saline-alkali stress. The effect of spraying high-calcium foliar fertilizer containing 0.5% CaCl2 on "Xiangyou No. 15" rape seedlings was the most obvious, which decreased by 48.2% compared with saline-alkali stress. The plasma membrane permeability decreased more obviously after spraying high-calcium foliar fertilizer containing 0.5% and 1.0% CaCl2.

[0065] 4. Determination of Na + , K + , Ca 2+ contents and K + / Na + ratio in rape seedlings

[0066] After spraying high-calcium foliar fertilizer for 5 times, representative plants in each treatment were taken, and the same functional leaves were selected to determine Na + , K + , Ca 2+ contents and K + / Na + ratio by ion chromatography. The results are shown in Table 2. Figure 3

[0067] Analysis of results: under saline-alkali stress, the content of Na + in stems and leaves of rape seedlings increased significantly, and the contents of K + , Ca 2+ and K + / Na + ratio decreased obviously. After spraying high-calcium foliar fertilizer containing 1.0% CaCl2, the content of K + in stems and leaves of "Huayouza No. 62" increased by 8.4% compared with saline-alkali stress, and the content of K + in stems and leaves of "Xiangyou No. 15" increased by 12.5% compared with saline-alkali stress. The contents of Na + in stems and leaves of the two rape varieties decreased most obviously after spraying high-calcium foliar fertilizer containing 1.0% CaCl2, which decreased by 19.4% and 19.2% compared with saline-alkali stress, respectively. The K + / Na + ratio in stems and leaves of "Huayouza No. 62" increased most obviously after spraying high-calcium foliar fertilizer containing 1.0% CaCl2, which increased by 7.1% compared with saline-alkali stress, and the K + / Na + ratio in stems and leaves of "Xiangyou No. 15" increased most significantly after spraying high-calcium foliar fertilizer containing 0.5% CaCl2, which increased by 58.8% compared with saline-alkali stress.

[0068] ​In summary, the spraying of high calcium foliar fertilizer containing 0.5%-1.0% CaCl2 has the best effect on improving the salt-tolerance of crops.

[0069] Example 3

[0070] The ultrapure water and chemical fertilizer were mixed according to the ratio of ultrapure water:urea:water-soluble monoammonium phosphate:potassium sulfate = 1000:195.7:82.2:43.2, and the mixture was shaken in a shaking box at 30°C for 24 hours to obtain a water-soluble fertilizer. The water-soluble fertilizer was subjected to nutrient substance determination to make the N content ≥100 g / L, the P2O5 content ≥60 g / L, and the K2O content ≥40 g / L. The water-soluble fertilizer was diluted (diluted 500 times), and 1.0% CaCl2 was added to the diluted water-soluble fertilizer to obtain a high calcium foliar fertilizer lacking citric acid fermentation tail liquid.

[0071] The high calcium foliar fertilizer without citric acid tail liquid was tested together with the high calcium foliar fertilizer with citric acid tail liquid in Example 1.

[0072] The test time, method, and details were the same as in Example 2, and the treatment settings were as follows: (1) T1: NaHCO3 stress + spraying of an equal amount of distilled water; (2) T2: NaHCO3 stress + the high calcium foliar fertilizer screened in Example 2 (containing 1.0% CaCl2); (3) T3: NaHCO3 stress + the high calcium foliar fertilizer obtained in this example (containing 1.0% CaCl2, lacking citric acid fermentation tail liquid).

[0073] Sample determination and method:

[0074] 1. Determination of rape seedling growth indicators

[0075] The rape seedlings were carefully taken out of the flowerpots, the root system surface was washed with clean water to remove the vermiculite particles, the rape seedling root length and plant height were measured with a ruler, and the rape stem and leaf fresh weight and root fresh weight were weighed with a thousandth scale. The results are shown in Table 3.

[0076] Table 3 Effect of different high calcium foliar fertilizers on rape seedling biomass

[0077]

[0078] Result analysis: As can be seen from Table 3, spraying the two kinds of high calcium foliar fertilizers can alleviate the influence of salt and alkali stress on rape seedlings to different extents. Among them, the T2 treatment has the most significant effect on alleviating the fresh weight of stems and leaves and roots of "Huayouza No. 62" rape seedlings; compared with T1 treatment, the fresh weight of stems and leaves and roots of "Huayouza No. 62" rape seedlings is increased by 117.03% and 13.28%, respectively; while the T2 treatment and the T3 treatment have no significant difference in the effect of alleviating the fresh weight of stems and leaves and roots of "Xiangyou No. 15" rape seedlings.

[0079] 2. Determination of chlorophyll fluorescence parameters of rape seedlings

[0080] Three representative plants were selected from each repetition at rape seedling stage; the same functional leaves were selected, and the maximum photochemical efficiency (Fv / Fm) and potential photochemical efficiency (Fv / Fo) of chlorophyll fluorescence parameters were determined by using a portable pulse modulation fluorometer. The results are shown in Figure 4 .

[0081] Result analysis: Chlorophyll fluorescence parameters are variables or constant values used to describe the mechanism and physiological conditions of plant photosynthesis. The parameters change little under non-stress conditions, but significantly decrease under stress conditions. As can be seen from Figure 4 , under saline-alkali stress, T2 treatment significantly increased the potential photochemical efficiency of "Huayouza 62" and "Xiangyou 15", which was increased by 20.80% and 19.60% respectively compared with T1 treatment; while T3 treatment significantly reduced the potential photochemical efficiency of the two, which was reduced by 25.54% and 17.44% respectively compared with T1 treatment. T2 treatment significantly increased the maximum photochemical efficiency of "Huayouza 62", which was increased by 4.71% compared with T1 treatment; T3 treatment significantly reduced the maximum photochemical efficiency of "Huayouza 62" and "Xiangyou 15", which was reduced by 10.46% and 4.80% respectively compared with T1 treatment.

[0082] 3. Determination of antioxidant enzyme activity and malondialdehyde content of rape seedling leaves

[0083] The malondialdehyde content was determined by the thiobarbituric acid method; the superoxide dismutase (SOD) and peroxidase (POD) activities were determined by using the nitro blue tetrazolium method and guaiacol method respectively. The results are shown in Figure 5 .

[0084] Result analysis: As can be seen from Figure 5 , T2 treatment had the most significant effect on the increase of antioxidant enzyme activity and the decrease of malondialdehyde content of the two rape leaves. The POD enzyme activity of "Huayouza 62" leaves under T2 treatment was increased by 35.76% and 12.19% respectively compared with T1 and T3 treatments; the POD enzyme activity of "Xiangyou 15" leaves under T2 treatment was increased by 15.84% and 11.80% respectively compared with T1 and T3 treatments; the SOD enzyme activity of "Huayouza 62" leaves under T2 treatment was increased by 17.54% and 26.21% respectively compared with T1 and T3 treatments; the SOD enzyme activity of "Xiangyou 15" leaves under T2 treatment was increased by 66.21% and 28.53% respectively compared with T1 and T3 treatments; the malondialdehyde content of "Huayouza 62" leaves under T2 treatment was reduced by 41.29% and 12.27% respectively compared with T1 and T3 treatments; the malondialdehyde content of "Xiangyou 15" leaves under T2 treatment was reduced by 36.45% and 36.41% respectively compared with T1 and T3 treatments.

[0085] 4. The determination of Na + , K + contents in rape seedling stage plant body, K + / Na +

[0086] After spraying 5 times of different high calcium foliar fertilizers containing 1.0% CaCl2 on rape seedling stage respectively, representative plants under each treatment were taken; the same functional leaves were selected, and ion chromatograph was used to determine Na + , K + contents, and calculate K + / Na + parameters. The results are shown in Figure 6

[0087] Result analysis: As can be seen from Figure 6 , spraying two kinds of high calcium foliar fertilizers can reduce the Na + content in rape leaves under saline-alkali stress to different degrees, and improve K + / Na + . Among them, the Na + content in the leaves of "Xiangyou 15" under T2 treatment is reduced by 19.16% and 11.08% respectively compared with T1 and T3 treatments; the K + / Na + of "Huayouza 62" under T2 treatment is increased by 7.12% and 38.61% respectively compared with T1 and T3 treatments, and the K + / Na + of "Xiangyou 15" under T2 treatment is increased by 23.70% and 12.62% respectively compared with T1 and T3 treatments.

[0088] The above examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements of the technical solutions of the present application made by those skilled in the art shall fall within the protection scope determined by the claims of the present application.​​

Claims

1. A high-calcium foliar fertilizer that enhances crop salt and alkali tolerance, characterized in that, The high-calcium foliar fertilizer uses citric acid fermentation tail liquid, inorganic chemical fertilizer and anhydrous calcium chloride as raw materials, and includes the following effective components at the following concentrations: ≥0.4 g / L organic matter, ≥0.2 g / L N, ≥0.12 g / L P2O5, ≥0.08 g / L K2O and 0.25%~2.0% anhydrous calcium chloride; The main components of the citric acid fermentation tail liquid are: organic matter ≥220 g / L, pH (1:250) = 4.2~6.2, N = 8~12 g / L, K2O = 16~20 g / L, amino acids = 8.5~9.5 g / L, total sugar = 75~85 g / L, peptides = 35~40 g / L; The inorganic chemical fertilizer is urea, potassium sulfate, and water-soluble monoammonium phosphate, wherein the urea contains N ≥ 46.0%, the potassium sulfate contains K2O ≥ 51%, and the water-soluble monoammonium phosphate contains P2O5 ≥ 73%. The preparation method of the high-calcium foliar fertilizer includes the following steps: (1) The citric acid fermentation tail liquid is used as the mother liquor; (2) The mother liquor and the inorganic chemical fertilizer are mixed in a ratio of mother liquor: urea: water-soluble monoammonium phosphate: potassium sulfate = (950~1050): (190~200): (80~85): (40~45); the mixing is carried out by shaking in a shaking box at a constant temperature of 28~32℃ for 22~26 h. (3) The nutrient content of the mixture is determined to meet the following requirements: organic matter content ≥220 g / L, N content ≥100 g / L, P2O5 content ≥60 g / L and K2O content ≥40 g / L, to obtain liquid fertilizer, and the liquid fertilizer is diluted 450~550 times. (4) Mix the diluted liquid fertilizer with anhydrous calcium chloride to achieve an anhydrous chlorine content of 0.25-2.0%, and adjust the pH to 6.5-7.5 to obtain the high-calcium foliar fertilizer.

2. The method for preparing the high-calcium foliar fertilizer according to claim 1, characterized in that, Includes the following steps: (1) The citric acid fermentation tail liquid is used as the mother liquor; (2) The mother liquor and the inorganic chemical fertilizer are mixed in a ratio of mother liquor: urea: water-soluble monoammonium phosphate: potassium sulfate = (950~1050): (190~200): (80~85): (40~45); the mixing is carried out by shaking in a shaking box at a constant temperature of 28~32℃ for 22~26 h. (3) The nutrient content of the mixture is determined to meet the following requirements: organic matter content ≥220 g / L, N content ≥100 g / L, P2O5 content ≥60 g / L and K2O content ≥40 g / L, to obtain liquid fertilizer, and the liquid fertilizer is diluted 450~550 times. (4) Mix the diluted liquid fertilizer with anhydrous calcium chloride to achieve an anhydrous chlorine content of 0.25-2.0%, and adjust the pH to 6.5-7.5 to obtain the high-calcium foliar fertilizer.

3. The preparation method according to claim 2, characterized in that, In step (2), the mixing ratio of mother liquor and inorganic chemical fertilizer is: mother liquor: urea: water-soluble monoammonium phosphate: potassium sulfate = 1000: 195.7: 82.2: 43.

2.

4. The preparation method according to claim 3, characterized in that, In step (3), the liquid fertilizer is diluted 500 times.

5. The preparation method according to claim 4, characterized in that, In step (4), ammonia is used to adjust the pH.

6. The application of the high-calcium foliar fertilizer according to claim 1 or the high-calcium foliar fertilizer prepared by any of the preparation methods according to claims 2 to 5 in crop cultivation.

7. The application according to claim 6, characterized in that, The high-calcium foliar fertilizer mentioned in this application is used during the seedling stage of the crop.

8. The application according to claim 6, characterized in that, The specific application is in the cultivation of salt-tolerant crops.

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