Method for increasing biomass, yield and nitrogen utilization rate of crops, and iron-rich compound fertilizer

Abstract

Provided in the present disclosure are a method for increasing the biomass, yield and nitrogen utilization rate of crops, and an iron-rich compound fertilizer. The method comprises: supplementing and applying an iron fertilizer to a crop, wherein the microelement iron in the iron fertilizer can significantly promote the absorption and assimilation of the mineral nutrition of a nitrogen-containing chemical fertilizer by the crop to which the fertilizer is applied, thereby producing a synergistic effect, and the amount of the iron fertilizer applied to the crop is 0.37-0.74 kg per Chinese acre. Moreover, by means of the method provided by the present disclosure, the tillering number and the nutrient absorption and utilization of the crop can be improved after fertilization according to a method for field crops and normal field management of crops, thereby effectively improving the biomass, yield and nitrogen utilization rate of the crop.

Description

Method for improving crop biomass, yield and nitrogen utilization rate and iron-rich compound fertilizer Technical Field

[0001] The present disclosure relates to the technical field of crop fertilizers and fertilization, and in particular to a method for increasing crop biomass, yield and nitrogen utilization rate, an iron-rich compound fertilizer and applications thereof. Background Art

[0002] Rice and wheat are important food crops, and their production is crucial for addressing the food crisis and is crucial to the national economy. With population growth, declining arable land, and increasing water scarcity, the imbalance between food demand and demand is becoming increasingly prominent, making increasing rice and wheat production imperative.

[0003] Currently, the application of chemical fertilizers is the primary measure for increasing rice and wheat yields, but traditional compound fertilizer formulas are inefficient. To boost yields, fertilizer application rates are often blindly increased. However, despite significant annual increases in fertilizer application, grain production has only grown slowly. Excessive fertilizer application leads to soil residue and acidification, causing residual fertilizer to escape into rivers, lakes, and oceans, causing serious environmental pollution and ecological imbalance while also increasing grain production costs. Furthermore, current fertilization practices are plagued by excessive nitrogen fertilizer application and low nitrogen utilization rates.

[0004] Therefore, improving nitrogen utilization efficiency during fertilization is not only related to the vital interests of farmers, but also to food safety and environmental quality. Developing a fertilizer formula that can significantly increase yields while reducing costs is of great significance and has good application prospects for achieving green and high yields of rice and wheat.

[0005] Summary of the Invention

[0006] In response to the above technical problems, the present disclosure provides a method for improving crop biomass, yield and nitrogen utilization efficiency, an iron-rich compound fertilizer and its application, in order to at least partially solve the above-mentioned technical problems.

[0007] In order to solve the above technical problems, the present disclosure provides the following technical solutions:

[0008] As a first aspect of the present disclosure, there is provided a method for increasing crop biomass, yield and nitrogen utilization efficiency, comprising:

[0009] Supplementing iron fertilizer to crops allows the trace element iron in the iron fertilizer to promote the crops' absorption and assimilation of mineral nutrients in nitrogen-containing fertilizers, thus playing a synergistic role;

[0010] Among them, the application amount of iron fertilizer is 0.37 to 0.74 kilograms per mu.

[0011] According to an embodiment of the present disclosure, the molar concentration ratio of nitrogen in the nitrogen-containing fertilizer to iron in the iron fertilizer is 83:1 to 20:1, which is applicable to the improvement of any fertilizer.

[0012] According to an embodiment of the present disclosure, when applied to foliar spraying, the molar concentration ratio of nitrogen in the nitrogen-containing fertilizer to iron in the iron fertilizer is 83:1 to 1.5;

[0013] When used for root fertilization, the molar concentration ratio of nitrogen in nitrogen-containing fertilizers to iron in iron fertilizers is 50:1~2.5.

[0014] As a second aspect of the present disclosure, there is provided an iron-rich compound fertilizer comprising:

[0015] Nitrogen fertilizer, iron fertilizer;

[0016] The molar concentration ratio of nitrogen in the nitrogen fertilizer to iron in the iron fertilizer is 83:1 to 20:1, so as to increase crop biomass, grain yield and nitrogen utilization efficiency.

[0017] According to an embodiment of the present disclosure, when applied to root fertilization, the iron-rich compound fertilizer further includes: phosphorus fertilizer and potash fertilizer, so that the compound fertilizer can be applied to the roots of crops;

[0018] Among them, the molar concentration ratio of nitrogen in nitrogen fertilizer, phosphorus in phosphorus fertilizer and potassium in potash fertilizer is 50:15~25:8~15.

[0019] According to an embodiment of the present disclosure, the nitrogen fertilizer includes any one or more of sodium nitrate, calcium nitrate, ammonium nitrate, calcium ammonium nitrate, ammonium sulfate nitrate, and urea;

[0020] Iron fertilizers include: soluble free iron salts and / or chelated iron;

[0021] The chelated iron includes any one or more of sodium ferric ethylenediaminetetraacetate, ferric ethylenediamine di-o-hydroxyphenyl acetate, ferric diethylenetriamine pentaacetate, ferric N-hydroxyethylethylenediamine triacetate, ferric ethylenediamine di-o-hydroxy-p-methylphenyl acetate, ferric iminodisuccinate, and ferric ethylenediamine disuccinate.

[0022] According to an embodiment of the present disclosure, the phosphate fertilizer includes any one or more of superphosphate, triple superphosphate, calcium magnesium phosphate, and phosphate rock powder;

[0023] Potash fertilizers include: any one or more of potassium chloride, potassium sulfate, potassium dihydrogen phosphate, sylvite, potassium magnesium salt, carnallite, potassium nitrate, and kiln dust potash fertilizer.

[0024] As a third aspect of the present disclosure, there is provided an application of an iron-rich compound fertilizer for increasing crop yield, comprising:

[0025] Apply iron-rich compound fertilizer to crops during their growth, and manage production in the same manner as normal crop planting fields;

[0026] Crops include any one or more of agricultural crops and economic crops.

[0027] According to an embodiment of the present disclosure, the period for applying the iron-rich compound fertilizer includes: the tillering period;

[0028] Tillering period includes: early tillering period, middle tillering period and late tillering period;

[0029] Crops are tillering crops, including rice, wheat, barley, and millet;

[0030] Cash crops include forage, vegetables and fruits.

[0031] According to the embodiments of the present disclosure, iron-rich compound fertilizer is sprayed on the leaves or poured into the roots in the early stage of crop tillering to promote crop tillering and improve crop yield and nitrogen utilization rate.

[0032] According to an embodiment of the present disclosure, the crop is rice containing the OsNLP4 gene or a crop containing an OsNLP4 homologous gene.

[0033] According to an embodiment of the present disclosure, rice varieties include wild-type rice and transgenic rice;

[0034] Wild rice includes japonica rice and indica rice.

[0035] According to an embodiment of the present disclosure, types of japonica rice include: Zhonghua 11, Longjing 31;

[0036] Indica rice types include: Xiushui 134, 9311, and R527;

[0037] Transgenic rice includes: OsNLP4 gene knockout mutant in japonica rice Zhonghua 11 background and OsNLP4 overexpression rice.

[0038] According to an embodiment of the present disclosure, an iron-rich compound fertilizer is applied to a crop containing the OsNLP4 gene in the early tillering stage to significantly promote tillering of the crop, and improve the yield and nitrogen utilization efficiency of the crop.

[0039] Based on the above technical solutions, the present disclosure provides a method for increasing crop biomass, yield and nitrogen utilization efficiency, an iron-rich compound fertilizer and its application, which have at least one of the following beneficial effects:

[0040] (1) In the embodiments of the present disclosure, by supplementing iron fertilizer to crops and adjusting the application amount of iron fertilizer, the molar concentration ratio of iron in compound fertilizer is changed, and the ratio of nitrogen in nitrogen fertilizer and iron in iron fertilizer is balanced, the OsNLP4 protein can be strongly induced to enter the cell nucleus, promoting the absorption and utilization of nitrogen nutrients and the tillering of crops, thereby effectively increasing crop biomass, grain yield and nitrogen utilization rate.

[0041] (2) In the embodiments of the present disclosure, by determining the optimal period for supplementary application of iron fertilizer, the fertilizer formula, the application method and the target crops, the yield and nitrogen utilization rate of crops with tillering characteristics can be significantly improved, which provides theoretical support and technical guidance for improving the fertilization method of agricultural production, improving the fertilizer utilization efficiency, and achieving green and high-yield crops.

[0042] (3) In the embodiments of the present disclosure, the method of enhancing the synergistic effect of nitrogen-containing fertilizers by supplementing with iron fertilizers can be applied to various crops by methods such as foliar spraying or root irrigation, and is applicable to the improvement of any fertilizer. For example, iron fertilizer can be added to compound fertilizers containing multiple additives such as phosphorus, potassium, and zinc for improvement. The operation is simpler, the cost is low, and it is easy to promote.

[0043] (4) In the embodiments of the present disclosure, the supplementary application of iron fertilizer during the tillering period of crops can promote the tillering of crops during the tillering period, effectively improve the absorption and utilization of nitrogen and iron elements by crops, thereby increasing the yield and nitrogen utilization rate of crops and playing a synergistic role. DETAILED DESCRIPTION

[0044] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0045] However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is obvious that one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0046] Currently, the blind pursuit of high crop yields, coupled with excessive nitrogen fertilizer application and reliance on it, is a widespread phenomenon in agricultural production. However, despite the increased use of fertilizers, crop yields have not significantly improved. Instead, excessive fertilization has led to a series of environmental pollution problems and increased planting costs. One of the main reasons for this dilemma is the lack of a proper balance of fertilizer nutrients, which in turn leads to low fertilizer utilization.

[0047] In the process of realizing the research disclosed herein, it was found that iron (Fe) is a trace nutrient element necessary for the normal growth and development of plants and is an indispensable cofactor in many important cellular processes. It is not only an important component of iron-sulfur (Fe-S) clusters, heme and some ferritins, but also participates in physiological processes such as the synthesis of plant chlorophyll, respiration and redox reaction, and has a significant impact on the yield of crops and the protein content of grains. The iron content of compound fertilizers currently on the market is relatively low, and iron is only used as a trace element added to compound fertilizers. When plants need iron, it is necessary to add or spray iron fertilizers. In the crop planting stage, it is necessary to consume extra manpower or material resources to add iron, which is very inconvenient.

[0048] Iron also has a synergistic relationship with nitrogen, a major component of compound fertilizers, promoting nitrogen utilization efficiency in crops and increasing crop yields. However, conventional compound fertilizer formulas contain low iron content, which prevents crops from achieving optimal nutrient utilization. Therefore, improving the iron content in compound fertilizers is crucial to increase crop utilization efficiency and reduce fertilizer input costs, thereby providing a means for green and sustainable agricultural development.

[0049] In view of the technical problems existing in the related art, the present disclosure provides a method for increasing crop biomass, yield and nitrogen utilization rate and an iron-rich compound fertilizer. By increasing the trace element iron in the fertilizer and balancing the nitrogen-iron ratio in the fertilizer, the biomass, yield and nitrogen utilization rate of crops can be significantly improved. It also provides a guide for the innovation of new compound fertilizer formulas and the iron-rich improvement of existing chemical fertilizers, so as to significantly improve the nitrogen utilization rate and yield of crops and reduce the application amount of nitrogen fertilizer.

[0050] Specifically, as a first aspect of the present disclosure, a method for increasing crop biomass, yield and nitrogen utilization efficiency is provided, comprising:

[0051] Supplementing iron fertilizer to crops allows the trace element iron in the iron fertilizer to promote the crops' absorption and assimilation of mineral nutrients in nitrogen-containing fertilizers, thus playing a synergistic role;

[0052] Among them, the application amount of iron fertilizer is 0.37 to 0.74 kilograms per mu.

[0053] According to the embodiments of the present disclosure, by supplementing the application of iron fertilizer, the molar concentration of iron in the fertilizer is increased, which can be synergistically utilized with nitrogen, one of the main components of compound fertilizers, to induce the OsNLP4 protein in the crop to enter the cell nucleus, regulate the genes in the crop cell nucleus, and promote the nitrogen utilization efficiency of the crop under the action of iron and nitrogen to increase crop yield. The application rate of iron fertilizer can be 0.37 kg per mu, 0.45 kg per mu, 0.7 kg per mu, 0.74 kg per mu, etc., but is not limited to the listed values, and other values ​​not listed within this numerical range are also applicable.

[0054] According to an embodiment of the present disclosure, the molar concentration ratio of nitrogen in the nitrogen-containing fertilizer to iron in the iron fertilizer is 83:1 to 20:1, which is applicable to the improvement of any fertilizer.

[0055] According to the embodiments of the present disclosure, for example, the ratios may be 83:1, 83:1.5, 50:1.5, 50:2, 50:2.5, etc., but are not limited to the listed values. Other values ​​not listed within this range are also applicable. This ratio adjustment method is applicable to the improvement of all fertilizers. By balancing the nitrogen-iron ratio of the fertilizer, it can increase crop biomass, grain yield, and nitrogen utilization efficiency.

[0056] According to an embodiment of the present disclosure, when applied to foliar spraying, the molar concentration ratio of nitrogen in the nitrogen-containing fertilizer to iron in the iron fertilizer is 83:1 to 1.5;

[0057] When used for root fertilization, the molar concentration ratio of nitrogen in nitrogen-containing fertilizers to iron in iron fertilizers is 50:1~2.5.

[0058] According to an embodiment of the present disclosure, when the method of foliar spraying of nitrogen-iron compound fertilizer is adopted, the molar concentration ratio of nitrogen in nitrogen-containing fertilizer and iron in iron fertilizer can be, for example, 83:1, 83:1.25, 83:1.5, etc., and only nitrogen fertilizer and iron fertilizer can be used for configuration, and the fertilizer can be applied more evenly by foliar spraying, especially for compound fertilizer containing trace elements of iron.

[0059] According to the embodiments of the present disclosure, when applied to root fertilization, the molar concentration ratio of nitrogen in nitrogen-containing fertilizers and iron in iron fertilizers can be, for example, 50:1, 50:1.25, 50:1.5, 50:2, etc., which can be used to improve all other compound fertilizers for root application, promote crop tillering to absorb mineral nutrients in fertilizers to increase crop yields.

[0060] As a second aspect of the present disclosure, there is provided an iron-rich compound fertilizer comprising:

[0061] Nitrogen fertilizer, iron fertilizer;

[0062] The molar concentration ratio of nitrogen in the nitrogen fertilizer to iron in the iron fertilizer is 83:1 to 20:1, so as to increase crop biomass, grain yield and nitrogen utilization efficiency.

[0063] According to an embodiment of the present disclosure, when used for root fertilization, the iron-rich compound fertilizer also includes: phosphate fertilizer and potash fertilizer, so that the compound fertilizer can be fertilized at the roots of crops; wherein the molar concentration ratio of nitrogen in the nitrogen fertilizer, phosphorus in the phosphate fertilizer, and potassium in the potash fertilizer is 50:15 to 25:8 to 15. For example, the molar concentration ratio of nitrogen:phosphorus:potassium in the compound fertilizer can be 50:15:8, 50:20:8, 50:25:10, 50:20:15, 50:25:10, etc., but is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable. Among them, 50:20:10 can be preferred.

[0064] According to an embodiment of the present disclosure, when applied to leaves for spraying, the iron-rich compound fertilizer is configured into a nitrogen-iron compound fertilizer aqueous solution for spraying, and the nitrogen-iron compound fertilizer aqueous solution can be composed of a nitrogen fertilizer aqueous solution and a chelate iron fertilizer aqueous solution.

[0065] According to the embodiments of the present disclosure, the proportion formula of the iron-rich compound fertilizer can meet the needs of crops for intake of various elements during the growth stage, simplify the fertilization process during planting, improve fertilization efficiency, and effectively save manpower and material resources.

[0066] According to an embodiment of the present disclosure, the nitrogen fertilizer includes any one or more of sodium nitrate, calcium nitrate, ammonium nitrate, calcium ammonium nitrate, ammonium sulfate nitrate, and urea. Other nitrogen-containing compounds may also be selected as needed.

[0067] According to an embodiment of the present disclosure, the iron fertilizer includes: soluble free iron salts and / or chelated iron;

[0068] The chelated iron includes any one or more of ethylenediaminetetraacetic acid sodium iron (EDTA-Fe), ethylenediamine di-o-hydroxyphenyl iron (EDDHA-Fe), diethylenetriamine pentaacetic acid iron (DTPA-Fe), N-hydroxyethylethylenediamine triacetic acid iron (HEDTA-Fe), ethylenediamine di-o-hydroxy-p-methylphenyl iron (EDDHMA-Fe), iminodisuccinate iron (IDHA-Fe), and ethylenediamine disuccinate iron (EDDS-Fe).

[0069] According to the embodiments of the present disclosure, the iron fertilizer may be either soluble free iron salt or chelated iron, preferably chelated iron. The iron ions in chelated iron are not easily precipitated, are absorbed more efficiently by plants, and have a more stable fertilizer effect.

[0070] According to the embodiment of the present disclosure, the concentration of the nitrogen fertilizer aqueous solution in the nitrogen-iron compound fertilizer aqueous solution used for leaf spraying is 0.1-1.5%, for example, the concentration of the urea aqueous solution is 0.1-1.5%, which can be selected as 0.1%, 0.5%, 1.0%, 1.5%, etc.; the concentration of the chelate iron fertilizer aqueous solution is 0.5-1.5mM, for example, the concentration of the EDTA-Fe aqueous solution is 0.5-1.5mM, which can be selected as 0.5mM, 1.0mM, 1.5mM, etc.; the amount of the nitrogen-iron compound fertilizer aqueous solution sprayed each time is 500-600L / hm 2 , of which 500L / hm2 can be selected 2 、550L / hm 2 、600L / hm 2 wait.

[0071] According to an embodiment of the present disclosure, the phosphate fertilizer includes any one or more of superphosphate, double superphosphate, calcium magnesium phosphate, and phosphate rock powder. Other phosphorus-containing compounds may also be selected as needed.

[0072] Potash fertilizers include any one or more of potassium chloride, potassium sulfate, potassium dihydrogen phosphate, sylvite, potassium magnesium salt, carnallite, potassium nitrate, and kiln dust potash fertilizer. Other potassium-containing compounds may also be selected as needed.

[0073] It should be noted that nitrogen fertilizers, phosphorus fertilizers, potassium fertilizers and iron fertilizers are not limited to the types listed, and other fertilizers with the same properties and similar functions are also applicable.

[0074] As a third aspect of the present disclosure, there is provided an application of an iron-rich compound fertilizer for increasing crop yield, comprising:

[0075] Apply iron-rich compound fertilizer to crops during their growth, and manage production in the same manner as normal crop planting fields;

[0076] Crops include any one or more of agricultural crops and economic crops.

[0077] According to the embodiments of the present disclosure, the iron-rich compound fertilizer can be configured into a nitrogen-iron compound fertilizer aqueous solution and sprayed on the leaves of crops, or the iron-rich compound fertilizer can be used to improve any chemical fertilizer for root irrigation.

[0078] According to an embodiment of the present disclosure, the application period includes: tillering period;

[0079] Tillering period includes: early tillering period, middle tillering period and late tillering period;

[0080] Crops are tillering crops, including rice, wheat, barley, and millet;

[0081] Cash crops include forage, vegetables and fruits.

[0082] It should be noted that the application method of the iron-rich compound fertilizer provided in the present disclosure is also applicable to other crops with tillering characteristics, and is not limited to the agricultural crops and economic crops listed in the present disclosure. No further examples or limitations are given on the types and varieties of crops.

[0083] According to the embodiments of the present disclosure, iron-rich compound fertilizer is sprayed on the leaves or poured into the roots in the early stage of crop tillering to promote crop tillering and improve crop yield and nitrogen utilization rate.

[0084] According to the embodiments of the present disclosure, applying a novel iron-rich compound fertilizer to crops at appropriate stages during crop growth can promote tillering of the crops during the tillering period, increase the number of tillers, and thus improve crop yield. Compared to applying nitrogen fertilizer or iron fertilizer alone, or conventional compound fertilizers, the iron-rich compound fertilizer can further increase the number of tillers and improve crop yield and nitrogen utilization efficiency.

[0085] According to the embodiments of the present disclosure, the iron-rich compound fertilizer is prepared into a nitrogen-iron compound fertilizer aqueous solution and sprayed on the leaves of crops. The spraying frequency is 2 to 3 times with an interval of 5 to 7 days. The production management is the same as the normal crop planting field management. It can promote the tillering of crops during the tillering period, increase the number of tillers of crops, and thus increase the yield of crops.

[0086] According to an embodiment of the present disclosure, the crop is rice containing the OsNLP4 gene or a crop containing an OsNLP4 homologous gene.

[0087] According to the embodiments of the present disclosure, the OsNLP4 gene is a nitrogen-efficient utilization gene that can efficiently utilize nitrogen in compound fertilizers, promote rapid root growth of crops, and significantly promote stem and leaf growth and the development of tiller primordia.

[0088] According to the embodiments of the present disclosure, rice itself contains the OsNLP4 gene. When nitrogen fertilizer or chelated iron fertilizer is applied alone, the OsNLP4 protein can be induced to migrate from the cytoplasm to the cell nucleus, transcriptionally activate genes for tillering development, and promote rice tillering; a nitrogen-iron compound fertilizer aqueous solution obtained by mixing nitrogen fertilizer and chelated iron fertilizer in a ratio of 83:1 to 1.5 can further enhance the induction of OsNLP4 protein into the cell nucleus, further promoting rice tillering.

[0089] According to an embodiment of the present disclosure, rice varieties include wild-type rice and transgenic rice;

[0090] Wild rice includes japonica rice and indica rice.

[0091] According to an embodiment of the present disclosure, types of japonica rice include: Zhonghua 11, Longjing 31;

[0092] Indica rice types include: Xiushui 134, 9311, and R527;

[0093] Transgenic rice includes: OsNLP4 gene knockout mutant in japonica rice Zhonghua 11 background and OsNLP4 overexpression rice.

[0094] According to the embodiments of the present disclosure, the compound fertilizer provided by the present disclosure is also applicable to other crops with tillering characteristics, not limited to the rice, wheat and their varieties listed in the present disclosure. No further examples or limitations are given on the types and varieties of crops.

[0095] According to an embodiment of the present disclosure, an iron-rich compound fertilizer is applied to a crop containing the OsNLP4 gene in the early tillering stage to significantly promote tillering of the crop, and improve the yield and nitrogen utilization efficiency of the crop.

[0096] According to the embodiments of the present disclosure, transgenic rice contains more OsNLP4 protein. The use of the iron-rich compound fertilizer provided by the present disclosure can induce more OsNLP4 protein to enter the cell nucleus and promote rice tillering, thereby increasing its yield and nitrogen utilization efficiency more significantly than that of ordinary rice.

[0097] In order to make the purpose, technical solutions and advantages of the present disclosure more clear and explicit, the technical solutions and principles of the present disclosure are further explained below through specific embodiments in combination with the accompanying drawings. It should be noted that the following specific embodiments are only for illustration and the scope of protection of the present disclosure is not limited thereto.

[0098] Unless otherwise specified, the experimental materials and reagents used in the following examples are commercially available. Where specific techniques or conditions are not specified in the examples, these are conventional methods and can be performed according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0099] Field experiments were conducted using an OsNLP4 knockout mutant (nlp4-1) and an OsNLP4-overexpressing rice line (OE-9) from the japonica rice variety Zhonghua 11 (ZH11), the japonica rice variety Longjing 31 (LG31), the indica rice variety Xiushui 134 (XS134), the indica rice variety 9311, the indica rice variety R527, and the japonica rice variety Zhonghua 11. The nlp4-1 mutant was generated using CRISPR / Cas9-based gene editing, while the overexpressing line was obtained through Agrobacterium (EHA105) transformation and resistance screening.

[0100] Examples of the embodiments of the present disclosure are as follows:

[0101] Example 1

[0102] The study was conducted on the effect of iron-rich compound fertilizers on increasing crop biomass. The experimental site was a certain location in Hefei, Anhui Province. The formulas of the four compound fertilizers used in the experiment are as follows:

[0103] (1) Ordinary compound fertilizer 1: 1mM KNO3 + 2mM NaH2PO4·2H2O + 0.5mM K2SO4 + 0.05mM Fe(Ⅱ)-EDTA;

[0104] (2) Iron-rich compound fertilizer 1: 1mM KNO3+2mM NaH2PO4·2H2O+0.5mM K2SO4+0.2mM Fe(Ⅱ)-EDTA;

[0105] (3) Ordinary compound fertilizer 2: 5mM KNO3+2mM NaH2PO4·2H2O+0.5mM K2SO4+0.05mM Fe(Ⅱ)-EDTA;

[0106] (4) Iron-rich compound fertilizer 2: 5mM KNO3+2mM NaH2PO4·2H2O+0.5mM K2SO4+0.2mM Fe(Ⅱ)-EDTA.

[0107] The experimental subjects were: japonica rice variety Zhonghua 11 (ZH11), OsNLP4 gene knockout mutant (nlp4-1) under ZH11 background, and rice line with overexpression of OsNLP4 (OE-9). ZH11 treated with ordinary compound fertilizer 1 served as the control group.

[0108] Each compound fertilizer was applied to the roots of rice, 24 rice plants were treated, and 3 biological replicates (3 × 24 plants) were set up. Vermiculite pot experiments were conducted with a pot size of 15 × 15 × 15 cm. 3 , one rice plant was planted in each pot, and each group of 6 pots was placed in a hydroponic box (size 60×40×20cm) filled with nutrient solution. 3 ), add 10 liters of nutrient solution each time, for a total of 12 times.

[0109] Rice samples were collected after 30 days of growth, and biomass was counted. Significance and correlation analyses were performed using SPSS 20.0. The LSD and Duncan methods in the one-way ANOVA were used for significance analysis, with a significance level of 0.05. The specific results are shown in Table 1.

[0110] As shown in Table 1, the formula of iron-rich compound fertilizer 2 was the best formula that could significantly increase rice biomass in this experiment. The optimal ratio of nutrients in the iron-rich compound fertilizer was 5 mM KNO3 + 2 mM NaH2PO4·2H2O + 0.5 mM K2SO4 + 0.2 mM Fe(Ⅱ)-EDTA. Under this ratio, the molar concentration ratio of nitrogen in the nitrogen fertilizer to iron in the iron fertilizer was 50:2. At this ratio, the effect on increasing the biomass of OsNLP4-overexpressing rice was most significant.

[0111] Table 1. Effects of different compound fertilizers on rice biomass during growth period

[0112] Note: Letters a, b, c, d, e, f, g, h indicate significant differences, p < 0.05

[0113] Example 2

[0114] Research on the effect of iron-rich compound fertilizer on increasing the effective tiller number, yield and nitrogen utilization efficiency of rice:

[0115] The same compound fertilizer and experimental subjects as in Example 1 were used to apply compound fertilizer to the roots of crops for cultivation and cultivation, and the yield-increasing effects of different nitrogen-phosphorus-potassium-iron compound fertilizer formulas on rice were compared, with ZH11 applied with ordinary compound fertilizer 1 as the control group.

[0116] Samples were taken at the rice maturity stage, and tiller number, yield, and nitrogen utilization efficiency (yield obtained per unit mass of nitrogen in the nutrient solution) were calculated. The results of this experiment were analyzed for significance and correlation using SPSS 20.0. The LSD and Duncan methods in the one-way variance analysis were used for significance analysis, with a significance level of 0.05.

[0117] The specific experimental results are shown in Table 2, Table 3, and Table 4.

[0118] Table 2. Effects of different compound fertilizers on the number of rice tillers

[0119] Note: Letters a, b, c, d, e, f, g, h, i indicate significant differences, p < 0.05

[0120] Table 3. Effects of different compound fertilizers on rice yield

[0121] Note: Letters a, b, c, d, e, f, g, h, i indicate significant differences, p < 0.05

[0122] Table 4. Effects of different compound fertilizers on nitrogen utilization efficiency of rice

[0123] Note: Letters a, b, c, d, e, f, g, h, i indicate significant differences, p < 0.05

[0124] The experimental results in Tables 2 through 4 show that the application of iron-rich compound fertilizer 2 significantly increased tiller number per plant, yield, and nitrogen use efficiency (NUE) in wild-type rice (japonica rice variety Zhonghua 11, ZH11). However, because the rice plants received only compound fertilizer throughout their growth cycle (the vermiculite medium contained no nutrients), higher fertilization levels than those used in field management were employed to ensure significant experimental results. Consequently, NUE was lower than the average level observed in normal field management.

[0125] Tables 2-4 show that the number of tillers per plant in ZH11 rice treated with iron-rich compound fertilizer 2 increased by 2-fold (200%), yield by 10.44-fold (1044%), and nitrogen use efficiency by 1.28-fold (128%) compared to the control (ZH11, conventional compound fertilizer 1). The number of tillers per plant, yield, and nitrogen use efficiency of the OsNLP4 knockout mutant (nlp4-1) rice treated with iron-rich compound fertilizer 2 were also the highest among all treatments, but lower than those of the ZH11 rice line treated with iron-rich compound fertilizer 2. The OsNLP4-overexpressing rice (OE-9) treated with iron-rich compound fertilizer 2 showed the greatest increases among all treatments, with increases of 3.69-fold (369%), 15.11-fold (1511%), and 2.17-fold (217%), respectively, compared to the control (ZH11, conventional compound fertilizer 1).

[0126] It can be seen that iron-rich compound fertilizer 2 is the optimal formula that can significantly increase the tiller number, yield and nitrogen utilization efficiency of rice. The optimal nutrient ratio of the iron-rich compound fertilizer is 5mM KNO3+2mM NaH2PO4·2H2O+0.5mM K2SO4+0.2mM Fe(Ⅱ)-EDTA. Under this ratio, the molar concentration ratio of nitrogen in the nitrogen fertilizer to iron in the iron fertilizer is 50:2. At this ratio, the effect on increasing the biomass of OsNLP4-overexpressing rice is the most significant, especially the significant increase in the tiller number of OsNLP4-overexpressing rice, thereby effectively improving the yield and nitrogen utilization efficiency of OsNLP4-overexpressing rice.

[0127] Example 3

[0128] The effects of iron-rich compound fertilizers on increasing the number of effective tillers, yield, and nitrogen utilization efficiency of different rice varieties were studied:

[0129] The same compound fertilizer and cultivation methods as in Example 1 were used to apply compound fertilizer to the crop roots. The only difference was that the experimental subjects were replaced with the japonica rice variety Longjing 31 (LG31), the indica rice variety Xiushui 134 (XS134), the indica rice variety 9311, and the indica rice variety R527. The response of different rice types to the iron-rich compound fertilizer was studied. Rice lines that received standard compound fertilizer 1 served as controls.

[0130] Samples were collected at the maturity stage of different rice varieties, and tiller number, yield, and nitrogen use efficiency were calculated. Significance and correlation analyses were performed using SPSS 20.0. The LSD and Duncan methods in the one-way ANOVA were used for significance analysis, with a significance level of 0.05. The specific experimental results are shown in Tables 5, 6, and 7.

[0131] Table 5. Effects of different compound fertilizer ratios on the tiller number of wild-type rice

[0132] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0133] Table 6. Effects of different compound fertilizer ratios on wild rice yield

[0134] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0135] Table 7. Effects of different compound fertilizer ratios on nitrogen utilization efficiency of wild-type rice

[0136] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0137] The experimental results in Table 5 to Table 7 show that iron-rich compound fertilizers 1 and 2 all significantly increase the number of tillers, yield and nitrogen utilization efficiency of different rice varieties, among which iron-rich compound fertilizer 2 has the most significant effect, and the increase rate varies between different rice varieties. Since rice plants only have compound fertilizer to provide nutrition (vermiculite medium does not contain nutrition) throughout the growth cycle, in order to ensure that the experimental effect is obvious, the cultivation process adopts a fertilization level higher than that of field management, so the nitrogen utilization efficiency is lower than the average level of normal field management. The experimental results show that iron-rich compound fertilizer 2 is the best formula that can significantly increase the number of tillers, yield and nitrogen utilization efficiency of rice in the present embodiment, and nitrogen fertilizer and iron fertilizer have a significant effect on improving the number of tillers, yield and nitrogen utilization efficiency of different varieties of rice under the ratio conditions in iron-rich compound fertilizer 2.

[0138] Example 4

[0139] Research on the effect of iron-rich compound fertilizer on improving effective tiller number, yield and nitrogen utilization efficiency of wheat:

[0140] The same compound fertilizer and planting and cultivation method as in Example 1 were used to apply compound fertilizer to the roots of crops. The only difference was that the experimental object was replaced by the wheat variety Annong 210 (AN210), and the wheat applied with ordinary compound fertilizer 1 was used as the control group.

[0141] Samples were taken at the wheat maturity stage, and the tiller number, yield and nitrogen utilization efficiency were counted. SPSS 20.0 was used to perform significance analysis and correlation analysis on the measurement results of this experiment. The significance analysis method used was LSD and Duncan method in one-way variance, and the significance level was set at 0.05.

[0142] The specific experimental results are shown in Table 8, Table 9, and Table 10.

[0143] Table 8. Effects of different compound fertilizer ratios on the number of wheat tillers

[0144] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0145] Table 9. Effects of different compound fertilizer ratios on wheat yield

[0146] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0147] Table 10. Effects of different compound fertilizer ratios on nitrogen utilization efficiency of wheat

[0148] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0149] Tables 8-10 show that the wheat tillering number per plant, yield, and nitrogen use efficiency in the iron-rich compound fertilizer treatment group 2 were the highest among all combinations. However, the standard compound fertilizer treatment group 2 also increased wheat yield and nitrogen use efficiency compared to the control group, a pattern slightly different from that observed for rice. Because rice plants receive only compound fertilizer for their entire growth cycle (the vermiculite medium contains no nutrients), to ensure a significant effect, higher fertilization levels were used during cultivation than in field management. Consequently, nitrogen use efficiency was lower than the average level observed in normal field management.

[0150] Based on the above examples, it can be seen that the iron-rich compound fertilizer formula of the present invention has a more significant yield-increasing effect on wild-type rice (such as japonica rice Zhonghua 11) than ordinary compound fertilizers; for transgenic rice (such as rice with overexpression of OsNLP4), because it contains more OsNLP4 protein, the iron-rich compound fertilizer of the present invention can induce more OsNLP4 protein to enter the cell nucleus to promote the absorption and utilization of nitrogen nutrients and promote rice tillering, thereby increasing the number of tillers, yield and nitrogen utilization efficiency more significantly than ordinary rice (such as japonica rice Zhonghua 11) under the same fertilization conditions.

[0151] Example 5

[0152] The optimal application period of iron fertilizer to crops was studied by foliar spraying, with spraying carried out at the tillering and heading stages of the crops. The experimental location was a certain place in Huzhou City, Anhui Province.

[0153] 1 mM Fe(Ⅱ)-EDTA was sprayed onto the leaves of the crops, with ZH11 rice strains sprayed with water as the control group. Eighty plants were sprayed per treatment, with four biological replicates (4 × 80 plants). Spraying was performed on sunny afternoons, with atomized droplets evenly sprayed on both sides of the rice leaves. Three sprayings were performed, with a five-day interval between sprays, and a spray volume of 550 L / hm2 was used each time. 2 , field management follows normal production management.

[0154] Samples were taken at the rice maturity stage, and the tiller number, yield, and nitrogen utilization efficiency were counted. The measurement results were analyzed for significance and correlation using SPSS 20.0. The LSD and Duncan methods in the one-way variance were used for significance analysis, and the significance level was set at 0.05.

[0155] The experimental results are shown in Table 11, Table 12 and Table 13.

[0156] Table 11 Effects of iron fertilizer spraying at different application periods on crop tillering number

[0157] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0158] Table 12 Effects of spraying iron fertilizer at different application periods on crop yield

[0159] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0160] Table 13 Effects of iron fertilizer spraying at different application periods on crop nitrogen utilization efficiency

[0161] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0162] As shown in Tables 11-13, foliar iron application during the tillering stage in wild-type rice (japonica variety Zhonghua 11) increased tiller number by 9.5% compared to the control (HO), significantly increased yield per plant by 11%, and increased nitrogen use efficiency by 11.2%. The OsNLP4 knockout mutant (nlp4-1) was insensitive to foliar iron application, with no significant increase in tiller number or yield. However, the OsNLP4-overexpressing rice (OE-9) showed the greatest increases in tiller number, yield, and nitrogen use efficiency after iron application, increasing by 23.3%, 36.3%, and 36.5%, respectively.

[0163] There were no significant differences between the groups treated with water spraying at the heading and tillering stages, whereas the effects of iron fertilizer spraying were significant. Iron fertilizer spraying at the heading stage in wild-type rice Zhonghua 11 and an overexpressing rice (OE-9) showed no significant changes in tiller number, yield, or nitrogen use efficiency compared to water spraying under the same conditions. This experiment demonstrates that the tillering stage is a critical period for significantly increasing rice yield and nitrogen use efficiency through foliar iron fertilizer application. In particular, the tiller number in OsNLP4-overexpressing rice increased significantly, effectively improving yield and nitrogen use efficiency in OsNLP4-overexpressing rice.

[0164] Example 6

[0165] Iron-rich foliar fertilizer was prepared and sprayed at the tillering and heading stages of crops to study the yield-increasing effect of crops. The experimental site was a place in Lingshui County, Hainan Province.

[0166] The nitrogen-iron compound fertilizers with iron-rich compound fertilizer formulas used in the experiment are:

[0167] (1) Formula 1: 0.5% urea;

[0168] (2) Formulation 2: 1 mM Fe(Ⅱ)-EDTA;

[0169] (3) Formulation 3: 0.5% urea + 1 mM Fe(II)-EDTA;

[0170] (4) Formulation 4: 1.5 mM Fe(Ⅱ)-EDTA;

[0171] (5) Formulation 5: 0.5% urea + 1.5 mM Fe(Ⅱ)-EDTA;

[0172] (6) Formulation 6: 1% urea;

[0173] (7) Formulation 7: 1% urea + 1 mM Fe(Ⅱ)-EDTA;

[0174] (8) Formulation 8: 1% urea + 1.5 mM Fe(Ⅱ)-EDTA.

[0175] The experimental subjects were: japonica rice variety Zhonghua 11 (ZH11), OsNLP4 gene knockout mutant (nlp4-1) under the ZH11 background, and rice line overexpressing OsNLP4 (OE-9). ZH11 sprayed with water served as the control group.

[0176] Each fertilizer treatment method was sprayed on 100 crops, with 4 biological replicates (4×100 plants). The spraying was carried out during the tillering stage of rice development, and the spraying method and statistical method were the same as those in Example 5. Samples were taken at the rice maturity stage, and the number of tillers, yield, and nitrogen utilization efficiency were statistically analyzed. The measurement results were analyzed by significance analysis and correlation analysis using SPSS 20.0. The significance analysis method used was LSD and Duncan method in the single-factor variance, and the significance level was set to 0.05. The experimental results are shown in Tables 14, 15, and 16.

[0177] Table 14 Effects of spraying different formulations of nitrogen-iron compound fertilizer on the number of rice tillers

[0178] Note: Letters a, b, c, d, e, f, g indicate significant differences, p < 0.05

[0179] Table 15 Effects of spraying different formulas of nitrogen-iron compound fertilizer on rice yield

[0180] Note: Letters a, b, c, d, e, f, g indicate significant differences, p < 0.05

[0181] Table 16 Effects of spraying different formulas of nitrogen-iron compound fertilizer on nitrogen utilization efficiency of rice

[0182] Note: Letters a, b, c, d, e, f, g indicate significant differences, p < 0.05

[0183] As shown in Tables 14 to 16, spraying various formula concentrations of nitrogen-iron compound fertilizers affected rice tillering, yield, and nitrogen utilization efficiency, and the degree of influence varied. Foliar spraying of wild-type rice (ZH11) with nitrogen fertilizer alone (Formulas 1 and 6) during the tillering period did not significantly increase the number of tillers, yield, and nitrogen utilization efficiency. Foliar spraying of iron fertilizer alone (Formulas 2 and 4) significantly increased the number of tillers, yield, and nitrogen utilization efficiency. Foliar spraying of 0.5% urea + 1mM Fe(Ⅱ)-EDTA compound fertilizer (Formula 3) had the best effect, with the number of tillers, yield, and nitrogen utilization efficiency significantly increasing by 11.6%, 13.1%, and 12.9%, respectively, compared to the control group (H2O). Foliar spraying of a 0.5% urea + 1.5mM Fe(II)-EDTA compound fertilizer (Formulation 5) increased yields comparable to Formula 3 (13.9%), but the application cost was higher. Increasing the urea concentration (1%) resulted in lower yield increases compared to Formula 3 for various nitrogen-iron compound fertilizers (Formulations 7 and 8). Foliar spraying of Formula 3 significantly increased tiller number, yield, and nitrogen use efficiency in OsNLP4-overexpressing rice plants, significantly increasing by 39.3%, 42.3%, and 43.1%, respectively, compared to the control.

[0184] These experimental results are due to the fact that, under balanced nitrogen and iron conditions within the plant, OsNLP4 protein levels are high in the cell nucleus, enhancing transcriptional activation of genes key to tillering, leading to significant increases in rice tiller number, yield, and nitrogen use efficiency. However, when nitrogen fertilizer levels are too high and iron fertilizer levels are too low, OsNLP4 protein levels in the cell nucleus are low, severely impacting rice growth and yield. Similarly, when iron fertilizer levels are too high and nitrogen fertilizer levels are too low, rice growth is also adversely affected.

[0185] Therefore, the foliar spraying scheme of 0.5% urea + 1mM Fe(Ⅱ)-EDTA compound fertilizer (the reagents used in this scheme are calculated based on the price of analytical grade, and the spraying cost per mu of land is about RMB 6.4) is the most effective in increasing rice yield, especially for OsNLP4-overexpressing rice.

[0186] Example 7

[0187] The study was conducted on the effect of iron-rich foliar fertilization on improving effective tiller number, yield and nitrogen utilization efficiency of wheat. The experimental site was a certain place in Hefei, Anhui Province.

[0188] The same compound fertilizer and planting and cultivation method as in Example 6 were used, with the only difference being that the experimental object was replaced by wheat, the variety of which was Yangmai 13, and the wheat sprayed with clear water was used as the control group.

[0189] Wheat samples were collected at the maturity stage, and the tiller number, yield, and nitrogen utilization efficiency were counted. The measurement results were analyzed for significance and correlation using SPSS 20.0. The LSD and Duncan methods in the one-way variance were used for significance analysis, and the significance level was set at 0.05.

[0190] The experimental results are shown in Tables 17, 18 and 19.

[0191] Table 17 Effects of different formulas of nitrogen-iron compound fertilizers on the number of wheat tillers

[0192] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0193] Table 18 Effects of different formulas of nitrogen-iron compound fertilizers on wheat yield

[0194] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0195] Table 19 Effects of different formulas of nitrogen-iron compound fertilizers on nitrogen utilization efficiency of wheat

[0196] Note: Letters a, b, c, d, e, f, g, h, i, j indicate significant differences, p < 0.05

[0197] Tables 17 to 19 show that the patterns of change differ slightly from those observed for rice. Foliar spraying of wheat with nitrogen fertilizer alone during the tillering stage (Formulations 1 and 6) did not significantly increase tiller number, but yield and nitrogen utilization efficiency increased significantly. Foliar spraying of iron fertilizer alone (Formulations 2 and 4) significantly increased tiller number, but yield and nitrogen utilization efficiency did not. Foliar spraying of 0.5% urea with 1 mM Fe(III)-EDTA (Formulation 3) achieved the best results, significantly increasing tiller number, yield, and nitrogen utilization efficiency by 16.9%, 28.9%, and 29.6%, respectively, compared to the control (HO). This indicates that foliar spraying of nitrogen-iron fertilizer during the tillering stage can significantly increase tiller number in wheat, thereby effectively increasing field yield and nitrogen utilization efficiency. The optimal nitrogen-iron fertilizer formulation for wheat spraying is 0.5% urea with 1 mM Fe(III)-EDTA.

[0198] In summary, compared to conventional compound fertilizers, iron-rich compound fertilizers increase the proportion of iron nutrients and can effectively increase tiller number, yield, and nitrogen use efficiency of various crops (such as rice and wheat). When used to prepare nitrogen-iron compound fertilizers, the optimal formula is Formula 3: 0.5% urea + 1mM Fe(II)-EDTA, which can significantly increase crop yield, especially for OsNLP4-overexpressing rice. When used for fertilizer improvement, the optimal ratio of iron-rich compound fertilizers for different crops can be further determined to significantly increase crop yield and nitrogen use efficiency. It can also be used to improve the molar ratios of various elements in compound fertilizers containing nitrogen, phosphorus, potassium, and iron to achieve yield increases. Compared to Iron-Rich Compound Fertilizer 1, Iron-Rich Compound Fertilizer 2 increases the proportion of nitrogen nutrients and is more effective in promoting tiller number, yield, and nitrogen use efficiency of crops (such as rice and wheat). Iron-rich compound fertilizer 2 can be used as the most preferred compound fertilizer ratio for crops. According to the molar concentration ratio of the macroelements nitrogen, phosphorus, potassium and the trace element iron contained therein, the present disclosure sets a more suitable ratio range of the iron-rich compound fertilizer as a concentration ratio of nitrogen fertilizer, phosphorus fertilizer, potassium fertilizer and iron fertilizer of 50:15-25:8-15:1-2.5, preferably 50:20:10:1-2.5.

[0199] The specific embodiments of the present disclosure described above do not limit the scope of protection of the present disclosure. Any other corresponding changes and modifications made based on the technical concept of the present disclosure should be included in the scope of protection of the claims of the present disclosure.

Claims

1. A method for increasing crop biomass, yield and nitrogen utilization efficiency, comprising: Supplementing iron fertilizer to the crops, so that the trace element iron in the iron fertilizer promotes the crops to absorb and assimilate the mineral nutrients in the nitrogen-containing fertilizer, thus playing a synergistic role; Wherein, the application amount of the iron fertilizer is 0.37 to 0.74 kilograms per mu.

2. The method according to claim 1, wherein: The molar concentration ratio of nitrogen in the nitrogen-containing fertilizer to iron in the iron fertilizer is 83:1-20:1, and is suitable for improving any fertilizer.

3. The method according to claim 1 or 2, wherein: When applied to foliar spraying, the molar concentration ratio of the nitrogen in the nitrogen-containing fertilizer to the iron in the iron fertilizer is 83:1-1.5; When applied to root fertilization, the molar concentration ratio of nitrogen in the nitrogen-containing fertilizer to iron in the iron fertilizer is 50:1-2.

5.

4. An iron-rich compound fertilizer comprising: Nitrogen fertilizer, iron fertilizer; The molar concentration ratio of the nitrogen in the nitrogen fertilizer to the iron in the iron fertilizer is 83:1 to 20:1, so as to increase crop biomass, grain yield and nitrogen utilization rate.

5. The iron-rich compound fertilizer according to claim 4, wherein When applied to the roots, the iron-rich compound fertilizer also includes: phosphorus fertilizer and potassium fertilizer, so that the compound fertilizer can be applied to the roots of crops; Wherein, the molar concentration ratio of the nitrogen in the nitrogen fertilizer, the phosphorus in the phosphorus fertilizer and the potassium in the potassium fertilizer is 50:15-25:8-15.

6. The iron-rich compound fertilizer according to claim 4, wherein: The nitrogen fertilizer includes any one or more of sodium nitrate, calcium nitrate, ammonium nitrate, calcium ammonium nitrate, ammonium sulfate nitrate, and urea; The iron fertilizer includes: soluble free iron salt and / or chelated iron; The chelated iron includes any one or more of sodium ferric ethylenediaminetetraacetate, ferric ethylenediamine di-o-hydroxyphenyl acetate, ferric diethylenetriamine pentaacetate, ferric N-hydroxyethylethylenediamine triacetate, ferric ethylenediamine di-o-hydroxy-p-methylphenyl acetate, ferric iminodisuccinate, and ferric ethylenediamine disuccinate.

7. The iron-rich compound fertilizer according to claim 5, wherein The phosphate fertilizer includes any one or more of superphosphate, double superphosphate, calcium magnesium phosphate, and phosphate rock powder; The potash fertilizers include potassium chloride, potassium sulfate, potassium dihydrogen phosphate, sylvite, potassium magnesium salt, carnallite, potassium nitrate, Any one or more of ash-potash fertilizers.

8. An application of the iron-rich compound fertilizer according to any one of claims 4 to 7 in increasing crop yield, comprising: Apply iron-rich compound fertilizer to crops during their growth, and manage production in the same way as normal crop planting field management; The crops include any one or more of agricultural crops and economic crops.

9. The use according to claim 8, wherein: The periods for applying the iron-rich compound fertilizer include: tillering period; The tillering stage includes: early tillering stage, middle tillering stage and late tillering stage; The crops are tillering crops, including rice, wheat, barley, and millet; The economic crops include forage, vegetables and fruits.

10. The use according to claim 9, wherein: The iron-rich compound fertilizer is sprayed on the leaves or poured on the roots in the early stage of tillering of the crop, so as to promote the tillering of the crop and improve the yield and nitrogen utilization rate of the crop.

11. The use according to claim 9, wherein: The crop is rice containing the OsNLP4 gene or a crop containing an OsNLP4 homologous gene.

12. The use according to claim 9, wherein: The rice varieties include wild rice and transgenic rice; The wild type rice includes japonica rice and indica rice.

13. The use according to claim 12, wherein: The types of japonica rice include: Zhonghua 11, Longjing 31; The types of indica rice include: Xiushui 134, 9311, and R527; The transgenic rice includes: OsNLP4 gene knockout mutant and OsNLP4 overexpression rice under the background of japonica rice Zhonghua 11.

14. The use according to claim 11, wherein: The iron-rich compound fertilizer is applied in the early tillering stage of the crop containing the OsNLP4 gene, so as to significantly promote the tillering of the crop and improve the yield and nitrogen utilization rate of the crop.

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