Application of small molecule peptide in nitrogen fertilizer

Abstract

The invention provides an application of a small molecule peptide in a nitrogen fertilizer. Wherein the small molecule peptide is N-(1-oxopropyl)-L-isoleucyl-L-isoleucyl glycyl-L-leucinamide (PAPA), and the small molecule peptide is N-(1-oxopropyl)-L-isoleucyl-L-isoleucyl glycyl The invention provides application of PAPA as a synergist in promoting plants to absorb nitrogen elements in a nitrogen fertilizer. The mass ratio of PAPA to the nitrogen elements in the nitrogen fertilizer is (1: 10)-(1: 12000). The invention further provides application of the small molecule peptide composition in promoting plants to absorb nitrogen elements in nitrogen fertilizer, and the small molecule peptide composition comprises PAPA. The PAPA and the nitrogen fertilizer are uniformly mixed and then applied to crops, so that the growth of crop roots can be promoted at low temperature, the water absorption of the crops is improved, the photosynthesis efficiency of plants is promoted, the growth rate of the plants is increased, the demand on the nitrogen fertilizer is improved, the utilization rate of nitrogen elements is increased, and the absorption of the crops on the nitrogen elements in the nitrogen fertilizer is increased; and the purpose of increasing both production and income is achieved.

Description

Technical Field

[0001] The invention relates to the field of agriculture, and in particular to application of a small molecule peptide: N-(1-oxopropyl)-L-isoleucyl-L-isoleucylglycyl-L-leucinamide in nitrogen fertilizer. Background Art

[0002] During the growth process, crops often face the influence of adverse factors such as low temperature, which will seriously affect the growth and yield of crops. Plant frost damage is a non-infectious disease caused by climatic factors. There are usually three situations of low temperature frost damage: First, it is an indirect damage caused by low temperature. When there is wind or it is not too cold and the sun is sufficient, the transpiration rate of green crops is relatively high, and the soil temperature is very low, so that the roots absorb water very slowly, the water in the body cannot maintain a normal balance, and the tissue becomes dry and damaged. This is actually a kind of drought damage, also called winter drought; second, when the soil with high water content is frozen, especially when thawing and freezing are repeated, the frozen soil will destroy the close contact between the roots and the soil or tear the roots off. Before the root system has time to recover, it encounters atmospheric conditions that promote strong transpiration, and the plants will wither and die. This damage is called frost pull; third, at extremely low temperatures, the water in the plant tissue forms ice crystals, which harms the crop cells and tissues. The latter two situations are usually physical damages that occur when the temperature is below zero degrees Celsius. Many crops face the first type of frost damage during their growth.

[0003] The temperature range suitable for most crops to grow is 15-25℃. Under transpiration, water enters the plant body from the capillary roots, and at the same time brings nutrients from the soil into the plant body. When the soil temperature is below 15℃, the viscosity of the cytoplasm in the root system increases, and it is difficult for water to pass through the cytoplasm. At the same time, the respiration is weakened, affecting the root pressure. The lower temperature slows down the growth of the root system, which will hinder the increase of the water absorption surface. Leafy crops, whose leaf area accounts for a high proportion of the entire crop, still have a strong transpiration effect when the temperature is below 15℃, and the water absorption capacity of the root system at this time decreases as the temperature decreases. The leaves wither due to lack of water. Therefore, maintaining the vitality of the crop root system and maintaining the normal growth process of the crop is the key to preventing frost damage to crops at 0-15℃. At the same time, it is also important to maintain the absorption and conversion of nitrogen fertilizer by crops.

[0004] There are many measures to prevent frost damage at low temperatures, which can be divided into two categories. One is regulation with plant regulation function, such as highly active rooting substances such as naphthylacetic acid, indolebutyric acid, and indoleacetic acid. These substances are usually obtained by chemical synthesis and have high technical requirements for use. Improper use or dosage often causes serious pesticide damage (Pesticide Science and Management, 2013, 34(2), p56-58). The other is biostimulants such as humic acid from natural sources, seaweed extracts, and hydrolyzed animal and plant proteins. They are reported to have rooting and certain anti-low temperature effects, and promote the absorption of nitrogen fertilizers. Due to the different sources and processing techniques of these substances, the effects are usually not stable, and the effects of most of these substances are relatively weak (Phosphate Fertilizer and Compound Fertilizer, 2020.11, p22-26).

[0005] Peptide compounds also have practical uses in agriculture. The most widely used in agriculture are long-chain peptide compounds polyaspartic acid and polyglutamic acid, which are prepared by polymerization of the corresponding single amino acids. In actual agricultural production, they have the characteristics of moisturizing, stress resistance, and promoting crop growth. However, their low temperature resistance effect on crops is not very obvious. Some small molecule peptide compounds have been reported to have low temperature resistance effects. CN109824757A discloses a cyclic (isoleucine-isoleucine) dipeptide, which can reduce the frost damage of potted tomatoes at a concentration of 1-5ng / ml, but it is obtained from the fermentation of Paecilomyces variotii, and the fermentation and extraction process is complicated. CN109722430A discloses a formula containing glutathione as a crop stress defense enzyme, but it does not clarify whether it works and the effect on crops at low temperatures. Summary of the invention

[0006] N-(1-oxopropyl)-L-isoleucyl-L-isoleucylglycyl-L-leucinamide, referred to as PAPA, is prepared from natural sources of isoleucine and leucine, CAS: 256419-86-0, molecular weight: 469.33, solubility in water 0.37g / L (25°C).

[0007]

[0008] Leucine and isoleucine are important components of plant protein and play an important role in plant growth and development. However, this role is not significant, and the effect on crop growth at low temperatures and promoting the absorption and utilization of nitrogen is not outstanding. However, experiments have found that under conditions below 15°C, the leaf area of ​​leafy crops is relatively large, the transpiration is strong, and the root system is affected by low temperatures, the water absorption and conduction are slow, and the crop growth is easily affected significantly. When the small molecule peptide compound PAPA is used together with nitrogen fertilizer at low temperature, under low temperature conditions, especially in the range of -5℃-15℃, PAPA can stimulate the growth of the root system, maintain the water absorption activity of the root system, and absorb the nitrogen fertilizer in the soil into the crops, thereby promoting the good growth of the crops. At the same time, it stimulates the plants to produce some functional substances, such as the increase of proline, which will stabilize the metabolic process in the protoplasm colloid and tissues, and the increase of soluble protein, which can regulate substances and nutrients, and is used to increase and accumulate. It can improve the water retention capacity of cells and protect the life substances and biofilms of cells. Therefore, PAPA has a good anti-low temperature effect on leafy vegetables at low temperatures, and it also has a good absorption promoting effect on nitrogen fertilizers.

[0009] Therefore, the present invention provides an application of a small molecule peptide PAPA in promoting crop absorption of nitrogen in nitrogen fertilizer, which comprises adding PAPA to the nitrogen fertilizer, and the mass ratio of PAPA to the nitrogen in the nitrogen fertilizer is 1:10 to 1:12000.

[0010] The crops described in the present invention include not only leafy crops such as cabbage, celery, spinach, kale, rapeseed and lettuce whose leaves are the main food, but also various crop seedlings, such as cucumber, tomato, pepper, potato and peanut seedlings; wherein the seedlings in the present invention refer to plants in the growth period dominated by stem and leaf growth.

[0011] PAPA can increase the stress resistance of plants at low temperatures, increase the absorption of nitrogen in nitrogen fertilizers by plants, and promote the growth of crops, providing an effective solution for ensuring plant yields. Preferably, the plants are leafy crops and plant seedlings. The low temperature described in the present invention is generally lower than the temperature range for normal crop growth. In actual agricultural production, it usually refers to -10°C-15°C, especially -5°C-15°C.

[0012] Furthermore, the mass ratio of PAPA to the nitrogen element in the fertilizer is 1:50 to 1:6000, which is beneficial to promoting the absorption of nitrogen element in leafy vegetables as fertilizer under low temperature; preferably 1:200 to 1:2300; more preferably 1:350 to 1:2300.

[0013] The PAPA described in the present invention includes itself and salts, wherein the salts include organic salts and inorganic salts, wherein the organic salts include formates, acetates, propionates, citrates, malates and maleates, etc., and the inorganic salts include hydrochlorides, nitrates, sulfates and phosphates.

[0014] The nitrogen fertilizer described in the present invention refers to nitrogen-containing substances used in existing agriculture to promote crop growth, including inorganic fertilizers containing nitrogen such as urea, ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium phosphate, potassium nitrate, diammonium phosphate, diammonium hydrogen phosphate, ammonium polyphosphate or ammonia water, and also organic fertilizers containing nitrogen, such as feces, straw, fermented products of plants and animals, and other industrial wastes containing amino acids and nitrogen. The nitrogen fertilizer described in the present invention can be in the form of solid fertilizer, liquid fertilizer or paste fertilizer.

[0015] The nitrogen fertilizer described in the present invention can be a single fertilizer or a compound fertilizer, and it can also contain one or more trace elements. The compound fertilizer includes an inorganic compound fertilizer, an organic compound fertilizer or an organic-inorganic compound fertilizer. Inorganic compound fertilizer refers to fertilizers of various specifications in inorganic form, such as compound fertilizers composed of the nitrogen fertilizer described in the present invention and various types of potash fertilizers and phosphate fertilizers, such as urea, potassium chloride and diammonium phosphate. Organic compound fertilizers are organic compound fertilizers composed of various wastes and fermented materials that can be used in agriculture, such as a mixture of fermented pig manure and straw. Organic-inorganic compound fertilizers refer to compound fertilizers composed of the above two types of fertilizers, such as inorganic compound fertilizers containing ammonium sulfate, potassium sulfate, and diammonium phosphate, and compound fertilizers formed by adding humic acid.

[0016] The present invention also provides an application of a small molecule peptide composition in promoting crops to absorb nitrogen in nitrogen fertilizer, wherein the small molecule peptide composition includes PAPA, and PAPA is uniformly mixed with the nitrogen fertilizer and applied to the crop to stimulate the root growth of the crop and promote the absorption of the nitrogen fertilizer, and the mass ratio of PAPA to the nitrogen in the nitrogen fertilizer is 1:10 to 1:12000.

[0017] Furthermore, the application method includes foliar spraying, broadcasting, flushing or drip irrigation, etc.

[0018] Furthermore, the mass ratio of PAPA in the small molecule peptide composition to the nitrogen element in the fertilizer is 1:50 to 1:6000, which is beneficial to promoting the absorption of nitrogen elements in leafy vegetables as fertilizers under low temperatures.

[0019] Furthermore, the main component of the small molecule peptide composition is PAPA, and its dosage form can be a solid preparation or a liquid preparation. Among them, the solid preparation can be a granule, a powder, a water-dispersible granule, a soluble granule, a soluble powder or a tablet; the liquid preparation can be an emulsifiable concentrate, a suspension, a microemulsion, an emulsion in water, a microcapsule preparation, an oil suspension and a suspension seed coating agent, etc. The small molecule peptide composition can be any preparation in the national standard "Names and Codes of Pesticide Formulations" (GB / T 19378-2017).

[0020] In order to obtain a stable preparation, the small molecule composition may further include at least one auxiliary agent selected from fillers, solvents, surfactants, defoaming agents, preservatives and warning colors according to the characteristics of each preparation and the processing technology.

[0021] When the dosage form of the small molecule peptide composition is a solid preparation, the auxiliary agent includes an organic filler, an inorganic filler or any combination of the two, the organic filler includes one or more of starch, cellulose, modified starch and modified cellulose, and the inorganic filler includes one or more of diatomaceous earth, kaolin, clay, attapulgite and white carbon black. When the small molecule peptide composition is a powder, it is obtained by crushing and mixing various raw materials, and the crushing process can be air flow crushing or mechanical crushing. When the small molecule peptide composition is a granule, it is also necessary to add a viscous substance and a disintegrating substance, add a small amount of water or solvent to prepare a wet material, and then granulate to obtain it. The granulation method includes extrusion, drum, fluidized bed and disc granulation methods. When the small molecule peptide composition is a tablet, it can be obtained by directly pressing the powdered material containing PAPA into a dry tablet, or the granular material after granulation can be pressed into a tablet.

[0022] When the small molecule peptide composition is a liquid preparation, it includes an organic solvent, and the organic solvent includes a protic solvent or an aprotic solvent, a protic solvent such as methanol, ethanol, butanol, etc., and an aprotic solvent such as ethyl acetate, toluene, xylene, solvent oil, N-methylpyrrolidone, butanone, cyclohexanone, acetonitrile, etc. When the small molecule peptide composition is an oil suspension, it is mainly added to an inert oil, such as vegetable oil or mineral oil, and then necessary additives such as a dispersant, an emulsifier and a viscosity regulator are added, and a stable finished product is obtained after sand grinding.

[0023] Whether it is a solid preparation or a liquid preparation, the auxiliary agent may also include a surfactant. Functionally, the surfactant is an emulsifier, a wetting agent, a dispersant, a synergist or any combination thereof. Chemically, the surfactant may be a nonionic, anionic or cationic surfactant, and the auxiliary agent may contain one or more types of surfactants. Both solid preparations and liquid preparations are prepared using existing preparation processing methods.

[0024] Furthermore, the small molecule peptide composition includes uniformly mixed PAPA and nitrogen fertilizer. Thus, the preparation method of the small molecule peptide composition includes uniformly adding PAPA to the nitrogen fertilizer by a suitable manner during the preparation of the nitrogen fertilizer using the existing preparation process. Common methods for manufacturing solid fertilizers include high tower method, drum granulation method and spray granulation method, as well as mixed fertilizers. For example, in drum granulation, a composite fertilizer containing the substance is prepared by spraying the suspending agent of the PAPA. For the solid fertilizer prepared by the above method, the PAPA can also be coated on the surface of the fertilizer by a wrapping process. The method for preparing a liquid fertilizer containing PAPA includes directly adding it to the liquid fertilizer to allow it to fully dissolve to obtain the corresponding fertilizer, and also includes adding a suitable preparation of the compound to the liquid fertilizer to form a more stable liquid fertilizer.

[0025] The small molecule peptide composition can be used to evenly mix the PAPA-containing substance and the nitrogen fertilizer in a tank mixing manner, wherein the tank mixing method described in the present invention refers to any form of fertilizer, which is mixed with a PAPA solution or a product in the form of a preparation before use, and then applied, or is applied in the field in a short period of time in sequence by foliar spraying, broadcasting, flushing, drip irrigation or coating.

[0026] Therefore, after the above-mentioned small molecule peptide PAPA provided by the present invention is uniformly mixed with nitrogen fertilizer and applied to crops, it can promote the growth of crop roots at low temperatures, thereby improving the crop's absorption of water, promoting the efficiency of plant photosynthesis, and increasing the plant's growth rate, thereby increasing the demand for nitrogen fertilizer, improving the utilization rate of nitrogen, and increasing the crop's absorption of nitrogen in nitrogen fertilizer; the PAPA used in the present invention is a small peptide compound, the raw materials of which are derived from natural products, have the characteristics of low carbon emissions and are more environmentally friendly; the present invention provides an efficient solution for increasing agricultural production and income and ensuring crop safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 These are photos of the growth status of cucumber seedlings after the samples provided in Example 2 and Comparative Example 4 of the present invention were applied to the seedlings and maintained at 7° C. for 24 hours. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further described in detail below through specific implementation methods.

[0029] Unless otherwise specified, the terms used in the present invention are commonly used terms in the relevant field. The raw materials, equipment, preparation processes, testing methods, etc. used in the embodiments are all prior arts in the relevant field unless otherwise specified.

[0030] Example 1-8 Effect of PAPA dosage on plant growth

[0031] PAPA can increase the stress resistance of leafy crops or other plant seedlings at low temperatures, increase the absorption of nitrogen in nitrogen fertilizers, and promote crop growth. The following study uses 3-4 leaf cucumbers as the research object to test the content of free proline and soluble protein in cucumber leaves under different temperatures, different PAPA dosages, and added fertilizers. These two main antifreeze indicators are used to show the effects of different treatments. At the same time, experiments are set up to investigate the effects of different ratios of PAPA and N on the main antifreeze indicators of crops.

[0032] The treated samples are shown in Table 1, wherein the amount of urea used as nitrogen fertilizer in Examples 1 to 4 is 25 kg / mu, and the amount of PAPA is 10 g / mu; the amount of urea used as nitrogen fertilizer in Examples 5 to 8 is 25 kg / mu, and the amounts of PAPA are 1 g / mu, 2 g / mu, 4 g / mu, and 50 g / mu, respectively; Comparative Examples 1 to 4 are control groups, wherein Comparative Example 1 is 25 kg / mu of urea + 10 g / mu of γ-PGA (polyglutamic acid), and Comparative Example 2 uses 25 kg / mu of urea; Comparative Example 3 uses 10 g / mu of PAPA; Comparative Example 4 is a blank test (neither urea nor PAPA is applied). The N content of urea used in this test is 46.4%.

[0033] The treatment method is as follows: after the cucumber seedlings at the 3-4 leaf stage are transplanted into pots, after 2 days, the fertilizer and additives are diluted with water according to the treatment amount and then flushed into the pots. Three replicates are used for each treatment, and then the treated cucumber seedlings are placed under corresponding temperature conditions for 24 hours of growth. A leaf from each treatment is taken, and the free proline content is measured after extraction. The free proline is tested by the ninhydrin method (on the discussion of the reaction of proline and ninhydrin in the determination of proline content by the ninhydrin method, Plant Physiology Communications, 2005 (03), 365). The specific test method includes testing soluble protein by the Lowry method, and the specific test method is described in the public literature. The chlorophyll content is tested by the Japanese Konica Minolta SPAD-502Plus chlorophyll meter, and all tests take the average value of three tests. The results are shown in Table 1, where the growth conditions of Example 2 and Comparative Example 4 after the above treatment are as follows: Figure 1 shown.

[0034] Table 1. Results of indicators of cucumber seedlings under low temperature

[0035]

[0036] from Figure 1It can be seen that: the cucumber seedlings treated with Comparative Example 4 are obviously wilted, the leaves are soft and drooping, and the growth is not vigorous; while the cucumber seedlings treated with Example 2 are obviously growing vigorously, the leaves are stretched, and the growth vitality is strong; this is mainly because after 24 hours of low temperature treatment, the transpiration in the growth process of the cucumber seedlings still continues, but the speed at which the roots of the cucumber seedlings treated with Comparative Example 4 absorb water is significantly reduced, and the water in them cannot be balanced, thus showing the phenomenon of wilting; the roots of the cucumber seedlings treated with Example 4 can still absorb a large amount of water at low temperature, maintain the water balance therein, thereby achieving the purpose of still growing vigorously at low temperature.

[0037] Combined with Table 1, at low temperatures, nitrogen fertilizer and PAPA can effectively increase the content of proline, soluble protein and chlorophyll in cucumber leaves, which is better than either alone; at 7°C, overall, different ratios of nitrogen fertilizer and PAPA can increase the content of proline, soluble protein and chlorophyll in cucumber leaves to varying degrees, and are better than γ-PGA. Therefore, when the mass ratio of PAPA to nitrogen in nitrogen fertilizer (PAPA:N) is 1:200 to 1:12000, the absorption rate of nitrogen fertilizer can be effectively improved at low temperatures.

[0038] Example 9

[0039] This embodiment provides a 17-17-17 water-soluble fertilizer containing PAPA, with a trace element Zn content of 0.5% and a B content of 0.5%. Its composition is shown in Table 3.

[0040] The preparation method is to weigh the materials shown in Table 2 and then crush them twice.

[0041] Table 2 Composition of PAPA-containing water-soluble fertilizer

[0042]

[0043] Example 10

[0044] This embodiment provides a PAPA 7-25-15 compound fertilizer, in which Zn is 0.2%, B is 0.2%, Mn is 0.1%, Cu is 0.1%, Mg is 0.3%, and Mo is 0.05%. Its composition is shown in Table 3.

[0045] The preparation method is to weigh the materials shown in Table 3, crush them, and then extrude them into granules using a screw granulator.

[0046] Table 3 Composition of PAPA-containing water-soluble fertilizer

[0047]

[0048] Embodiment 11

[0049] This embodiment provides a 10-5-10 organic-inorganic compound fertilizer containing PAPA, with organic matter ≥10%, and its composition is shown in Table 4.

[0050] The preparation method is to dry the bean cake and the straw, weigh the materials shown in Table 4, and then crush them.

[0051] Table 4 Composition of organic and inorganic compound fertilizer containing PAPA

[0052]

[0053] Example 12

[0054] This embodiment provides a liquid fertilizer of PAPA. 1000 g of urea ammonium nitrate aqueous solution with a nitrogen content of 32%, including 120 g / L nitrate nitrogen, 120 g / L ammonia nitrogen, and 182 g / L amide nitrogen, is weighed and diluted with water to a nitrogen content of 28%. Then 0.12 g of PAPA (content 98%) is added and heated to 40° C. to dissolve completely to obtain a liquid nitrogen fertilizer in good condition, wherein N:PAPA=2333.3.

[0055] Embodiment 13

[0056] This embodiment provides a preparation of a PAPA suspension, and its composition is shown in Table 6.

[0057] After weighing the materials shown in Table 5, high shear was first performed, and then sand milled for 3 hours to obtain a stable 10% suspension product.

[0058] Table 5 Composition of PAPA suspension

[0059] Element Addition amount / g Mass content% Remark PAPA (98%) 10.2 10 Atlox4913 2 2 Atlox4894 2 2 Xanthan gum 0.1 0.1 Magnesium aluminum silicate 0.5 0.5 Preservative BT 0.2 0.2 water Top up to 100

[0060] Embodiment 14

[0061] This embodiment provides a preparation of an oil suspension of PAPA, and its composition is shown in Table 6.

[0062] After weighing the materials shown in Table 6, high shear was first performed, and then sand milled for 3 hours to obtain a stable 10% suspension product.

[0063] Table 6 PAPA oil suspension composition table water

[0064]

[0065]

[0066] Embodiment 15

[0067] This example provides a preparation method for 60% water dispersible granules of PAPA, the composition of which is shown in Table 7.

[0068] The preparation method comprises the following steps: air flow pulverizing the weighed material, adding 10% of the weight of the collected material into water for kneading, and then obtaining granules through a rotary granulator, and drying the granules to obtain the product.

[0069] Table 7. Composition of PAPA water dispersible granules

[0070] Element Addition amount / g Mass content% Remark PAPA (98%) 61.22 60.0 Dispersogen LFS 5 5.0 NNO 10 10.0 Pull open powder BX 2 2.0 PVP K30 2 2.0 Calcined Diatomaceous Earth Top up to 100

[0071] Example 16

[0072] This embodiment provides a compound fertilizer containing PAPA. 100 g of the 10% suspension prepared in Example 5 is weighed, 10 g of a 2% ethylene alcohol aqueous solution is added and stirred evenly, and then slowly added to 15 kg of solid compound fertilizer particles of 25-10-15, stirred to allow the liquid to evenly adhere to the fertilizer surface, and then dried to obtain a compound fertilizer containing PAPA, wherein N:PAPA=375.

[0073] The PAPA-containing preparations and fertilizers provided in the above embodiments can be applied to plants by root dipping, seed coating, foliar spraying, soil application or flushing.

[0074] Field implementation cases

[0075] The invention adopts ammonium dihydrogen phosphate (P2O5 content 61%, N content 12%), potassium sulfate (K2O content 52%), and urea (N content 46.4%) as raw materials to prepare a 370-80-50 water-soluble fertilizer. The water-soluble fertilizer preparation method comprises the following steps: weighing 765kg of urea, 132kg of ammonium dihydrogen phosphate, and 97kg of potassium sulfate, and then adding 3kg of a water-soluble anti-caking agent and 3kg of water-soluble starch, stirring the mixture fully and uniformly with a mechanical stirring device, randomly taking 3 batches of samples, and analyzing the contents of the three macroelements to determine that the contents are not less than the index of 370-80-50.

[0076] The field test was conducted in Renzhang Village, Sanqiao Town, Runan County, Henan Province. The soil in the test area was calcareous sand ginger black soil. The soil conditions were tested as follows: pH value was 7.11, organic matter content was 1.32%, and the test vegetable variety was large-leaf spinach, which was planted outdoors. Before celery was planted, decomposed pig manure was applied as base fertilizer at a dosage of 100kg / 667m 2 The experimental fields are covered with mulch and equipped with complete drip irrigation facilities, and the management level of the entire experimental plot is the same.

[0077] Each treatment area is 6.5m×5m, and repeated 3 times. The experiment adopts a randomized block design. Planting was carried out on February 25, 2024, and the number of celery planted in each treatment was 180. The first drip irrigation and fertilization was carried out on March 1, the second drip irrigation and fertilization was carried out on March 10, and the third drip irrigation and fertilization was carried out on March 25. The test results were investigated on April 5. The fertilization method is to weigh the corresponding fertilizer, add an appropriate amount of water to dissolve it, and then use it for drip irrigation; if the samples of the synergists shown in Table 8 are used, the synergist is first added to the corresponding fertilizer and mixed, and then drip fertilization is carried out. Among them, the synergist PAPA shown in Table 8 is a 10% suspension, and isoleucine and leucine are both 95% solid raw materials. For the blank treatment, the same amount of water was irrigated by drip irrigation.

[0078] Experimental time: 2024.02.25-2024.04.05. During this period, the temperature was in the range of -3℃-30℃. The main growing period was March 2024, with the lowest average temperature of 6℃ and the highest average temperature of 18℃.

[0079] Table 8. Effect of PAPA and fertilizer on spinach yield

[0080]

[0081]

[0082] Table 8 shows that the combined application of PAPA and nitrogen fertilizer can effectively improve crop products; although the crop yield increased with the increase in fertilizer dosage, it was not obvious. However, with the addition of PAPA, the yield increased significantly with the increase in fertilizer dosage; there was no significant synergistic effect when PAPA was used together with phosphorus and potassium fertilizers; compared with the synergist γ-PGA and leucine, PAPA and nitrogen fertilizer had a significant yield-increasing effect.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or some technical features can be replaced by equivalents without departing from the spirit of the technical solution of the present invention, which should be included in the scope of the technical solution for protection of the present invention.

Claims

1. Application of a small molecule peptide PAPA as a synergist in promoting plant absorption of nitrogen in nitrogen fertilizer, characterized in that: The mass ratio of PAPA to the nitrogen element in the nitrogen fertilizer is 1:10 to 1:12000; Preferably, PAPA comprises itself and its salts; Preferably, the salt of PAPA is an organic salt, including at least one of formate, acetate, propionate, citrate, malate and maleate; Preferably, the salt of PAPA is an inorganic salt, including at least one of hydrochloride, nitrate, sulfate and phosphate.

2. The use according to claim 1, characterized in that: PAPA stimulates plant root growth at low temperatures, wherein the low temperature is -10°C to 15°C; Preferably, the low temperature is -5°C-15°C; Preferably, the use is manifested as increasing the chlorophyll content, soluble protein content or free proline content in the plant.

3. The use according to claim 1 or 2, characterized in that: The mass ratio of PAPA to the nitrogen element in the fertilizer is 1:50 to 1:6000.

4. The use according to claim 1 or 2, characterized in that: The plants include leafy vegetables or seedlings of various crops; Preferably, the crops include cabbage, celery, spinach, kale, spinach, rapeseed or lettuce; Preferably, the crop seedlings include cucumber seedlings, tomato seedlings, pepper seedlings, potato seedlings or peanut seedlings.

5. The use according to claim 1 or 2, characterized in that: The nitrogen fertilizer is inorganic fertilizer, organic fertilizer or any two fertilizers containing nitrogen; Preferably, the inorganic fertilizer is urea, ammonium sulfate, ammonium nitrate, ammonium chloride, ammonium phosphate, potassium nitrate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, ammonium polyphosphate or ammonia water.

6. Application of a small molecule peptide composition in promoting plant absorption of nitrogen in nitrogen fertilizer, characterized in that: The small molecule peptide composition is firstly evenly mixed with the nitrogen fertilizer and then applied to plants; wherein the small molecule peptide composition includes PAPA, and the mass ratio of PAPA to the nitrogen element in the nitrogen fertilizer is 1:10 to 1:12000.

7. The use according to claim 6, characterized in that PAPA stimulates plant root growth at low temperatures, wherein the low temperature is -10°C to 15°C; Preferably, the low temperature is -5°C-15°C; Preferably, the use is manifested as increasing the chlorophyll content, soluble protein content or free proline content in the plant.

8. The use according to claim 7, characterized in that: The application methods include foliar spraying, broadcasting, flushing or drip irrigation.

9. The use according to claim 6, 7 or 8, characterized in that: The mass ratio of PAPA to the nitrogen element in the fertilizer is 1:50 to 1:6000.

10. The use according to claim 6, 7 or 8, characterized in that: The main component of the small molecule peptide composition is PAPA, and its dosage form is a solid preparation or a liquid preparation.

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