Light rare earth foliar fertilizer and method for increasing absorption capability of plant to mineral nutrient element

Abstract

A light rare earth foliar fertilizer and a method for increasing the absorption capability of a plant to a mineral nutrient element. The light rare earth foliar fertilizer comprises a solid light rare earth foliar fertilizer and a liquid light rare earth foliar fertilizer. The solid light rare earth foliar fertilizer comprises a trivalent light rare earth element (LREE), and the mass content of the trivalent LREE is 0.15-1.2%. The light rare earth foliar fertilizer is proposed on the basis of the discovered mechanism of trace LREEs inducing cascade endocytosis-transcytosis activation in trichomes and pavement cells in plant leaf epidermis. By means of this mechanism, the present invention can realize efficient absorption of mineral nutrients by plants, can solve the problem in the prior art of the excessively large application amount of rare earth foliar fertilizers, and is applicable to the technical field of plant nutrition.

Description

Light rare earth foliar fertilizer and method for increasing plant's ability to absorb mineral nutrients

[0001] This application is based on the Chinese application with CN application number 202410149238.4 and application date January 31, 2024, and claims its priority. The disclosed content of the CN application is again introduced as a whole into this application. Technical Field

[0002] The present invention relates to the technical field of plant nutrition, in particular to a light rare earth foliar fertilizer and a method for increasing a plant's ability to absorb mineral nutrients. Background Art

[0003] Fertilizer, as an important agricultural production material, is a crucial condition for ensuring food security. Although great progress has been made in developing more efficient fertilizers and fertilization strategies, low fertilizer or nutrient utilization efficiency remains a major obstacle to fertilizer application and the green transformation of agriculture. Therefore, it is imperative to develop innovative solutions that promote more effective plant nutrient absorption. Since Chinese and American scholars discovered in 1917 that leaf absorption of rare earth elements (REEs) has a "low-promoting and high-inhibiting" effect on the growth of sponge plants, agricultural experts have confirmed from theory to practice that the application of appropriate amounts of REEs to plant leaves can increase the plant's absorption of nutrients such as nitrogen, phosphorus, and potassium, and improve plant yield and quality. REEs are a general term for 17 elements in the periodic table of chemical elements, including 7 light REEs [LREEs, including lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm) and europium (Eu)] and 10 heavy REEs [HREEs, including gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), scandium (Sc) and yttrium (Y)].

[0004] To overcome the low nutrient absorption efficiency of foliar fertilizers, scientists began adding 16 trivalent REEs (REE(III), excluding one radioactive Pr) to foliar fertilizers in the 1970s, resulting in a diverse range of REEs-based foliar fertilizers, including REEs-based compound fertilizers, REEs-based foliar fertilizers, and REEs-based micronutrient fertilizers. However, despite the half-century of agricultural use of foliar fertilizers containing 16 REEs, key scientific questions remain: how the added REEs trigger nutrient absorption into leaves, and how leaf absorption patterns relate to dose-response relationships. As a result, there are many technical problems such as the large number of REEs added to foliar fertilizers, large REE application doses (Agathokleous E, Kitao M, Calabrese E J. Hormetic dose responses induced by lanthanum in plants[J]. Environmental Pollution, 2019, 244: 332-341.), and inappropriate REE foliar fertilizer application methods, which in turn lead to low absorption efficiency of mineral nutrients in fertilizers, hidden dangers to food safety and human health, and negative effects on agricultural production.

[0005] Summary of the Invention

[0006] The present invention has discovered a mechanism by which trace amounts of light rare earth elements (LREEs) induce the activation of a cascade of endocytosis and transcytosis in plant leaf epidermal trichomes and plating cells. This mechanism enables efficient mineral nutrient absorption by plants. Based on this novel mechanism, the present invention primarily aims to provide a light rare earth foliar fertilizer and a method for increasing a plant's ability to absorb mineral nutrients, addressing the issue of excessive application of rare earth foliar fertilizers in the prior art.

[0007] To achieve the above object, according to a first aspect of the present invention, a light rare earth foliage solid fertilizer is provided. The light rare earth foliage solid fertilizer comprises trivalent light rare earth elements, and the mass content of the trivalent light rare earth elements is 0.15% to 1.2%.

[0008] Furthermore, the light rare earth foliar solid fertilizer also contains mineral nutrient elements, which include one or more of nitrogen (N), phosphorus (P), potassium (K), sulfur (S), magnesium (Mg), calcium (Ca), manganese (Mn), zinc (Zn), copper (Cu), iron (Fe), chlorine (Cl), boron (B) or molybdenum (Mo).

[0009] Furthermore, in the light rare earth foliar solid fertilizer, the mass content of the N element is 10% to 20%, the mass content of the P element is 5% to 10%, the mass content of the K element is 20% to 30%, the mass content of the S element is 20% to 30%, the mass content of the Mg element is 4% to 5%, the mass content of the Ca element is 15% to 25%, the mass content of the Mn element is 0.01% to 0.02%, the mass content of the Zn element is 0.01% to 0.02%, the mass content of the Cu element is 0.001% to 0.002%, the mass content of the Fe element is 0.2% to 0.4%, the mass content of the Cl element is 1% to 3%, the mass content of the B element is 0.02% to 0.04%, and the mass content of the Mo element is 0.0005% to 0.001%.

[0010] To achieve the above object, according to a second aspect of the present invention, a light rare earth foliar liquid fertilizer is provided. The light rare earth foliar liquid fertilizer comprises an aqueous solution of a trivalent light rare earth element, and the concentration of the trivalent light rare earth element is 3.6 μM to 30 μM.

[0011] Furthermore, the light rare earth foliar liquid fertilizer also contains mineral nutrient elements, which include one or more of N, P, K, S, Mg, Ca, Mn, Zn, Cu, Fe, Cl, B or Mo.

[0012] Furthermore, in the light rare earth foliar liquid fertilizer, the concentration of N element is 0.05mM~0.11mM, the concentration of P element is 0.6mM~1.3mM, the concentration of K element is 1.8mM~3.1mM, the concentration of S element is 2.2mM~3.7mM, the concentration of Mg element is 0.58mM~0.82mM, the concentration of Ca element is 1.3mM~2.5mM, the concentration of Mn element is 0.6μM~1.5μM, the concentration of Zn element is 0.5μM~1.2μM, the concentration of Cu element is 0.06μM~0.13μM, the concentration of Fe element is 12μM~28μM, the concentration of Cl element is 0.1mM~0.3mM, the concentration of B element is 6.5μM~14.8μM, and the concentration of Mo element is 0.02μM~0.04μM.

[0013] Furthermore, the pH of the light rare earth foliar liquid fertilizer is 6.0-6.8.

[0014] In order to achieve the above-mentioned purpose, according to the third aspect of the present invention, a method for increasing the absorption capacity of plants for mineral nutrients is provided, the method comprising: spraying the above-mentioned light rare earth foliar liquid fertilizer, or the liquid fertilizer obtained by preparing the above-mentioned light rare earth foliar solid fertilizer, above the plant leaves; the spraying amount is limited to the amount that does not drop from the plant leaves; above the plant leaves includes 10 cm-2 m directly above the plant leaves.

[0015] Furthermore, the spraying time is from the time when the first true leaf of the plant is fully expanded to the time when the fourth true leaf is fully expanded.

[0016] In order to achieve the above-mentioned purpose, according to the fourth aspect of the present invention, there is provided an application of the above-mentioned light rare earth foliar solid fertilizer, or the above-mentioned light rare earth foliar liquid fertilizer, or the above-mentioned method for increasing the plant's ability to absorb mineral nutrients in plant cultivation.

[0017] By applying the technical solution of the present invention, in the above-mentioned light rare earth foliar solid fertilizer, the content of trivalent light rare earth elements is low, but it can still achieve the improvement of the ability of plant leaves to absorb mineral nutrient elements, thereby achieving the effect of promoting plant growth at low rare earth concentrations, reducing the application amount of rare earth elements, and reducing the accumulation of rare earth elements in plants and the increase in the background value of rare earth elements in the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0019] FIG1 shows the Zn 2+ Confocal fluorescence microscopy results of entering the plant body.

[0020] FIG2 shows the results of the effect of applying light rare earth foliar liquid fertilizer on plant traits according to Test Example 1 of the present invention.

[0021] FIG3 shows the results of the effect of applying light rare earth foliar liquid fertilizer on plant yield according to Test Example 1 of the present invention.

[0022] FIG. 4 shows a test diagram of the Tyndall effect of the sample according to Test Example 2 of the present invention.

[0023] FIG5 shows the adhesion work results of the sample according to Test Example 2 of the present invention on the surface of a plant leaf.

[0024] FIG6 shows a graph showing the absorption time results of the samples of Test Example 2 on leaf trichomes according to the present invention. DETAILED DESCRIPTION

[0025] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0026] As mentioned in the background art, rare earth fertilizers in the prior art have technical problems such as excessive application amount and inappropriate application method, which in turn lead to low absorption efficiency of mineral nutrients in fertilizers, hidden dangers to food safety and human health, and negative effects on agricultural production. In recent years, a large number of studies have shown that fertilizers containing a mixture of 16 REEs, including LREEs and HREEs, sold on the global market will cause human health risks (various HREEs have varying degrees of toxicity to the liver, kidneys, nervous system, etc., and can cause teratogenicity and carcinogenicity). The application amount of REEs in the prior art is large (80μM~200μM), which leads to the accumulation of REEs in plants and an increase in the background value of rare earth elements in the environment, which in turn affects food safety and human health.

[0027] In addition, the inventors have investigated and analyzed the application timing and application mode of existing foliar fertilizers, and found that the spraying timing of REEs foliar fertilizers on the market is included in multiple different developmental stages such as plant seedling stage, vigorous growth period and maturity period, such as rice, spraying in tillering stage, panicle differentiation stage and filling stage; soybean, spraying in seedling stage and flower pod stage, and the earliest seedling stage is also after the third true leaf. In these growth stages, the leaf epidermal trichomes are wrapped with a thick wax layer and a mineral layer, and there is also a thick wax layer in the leaf epidermis, so the absorption efficiency of mineral nutrients is very low. Moreover, in order to make each element in REEs foliar fertilizer exist in the form of ion state (i.e., bioavailable state), the pH of most REEs foliar fertilizers is adjusted to 4.0, causing plants to withstand the acid damage of low pH, such as burn spots appearing in leaves, photosynthesis being inhibited, thereby affecting the growth-promoting effect of REEs foliar fertilizers.

[0028] In this application, the inventors attempted to explore the mechanism by which rare earth elements affect the absorption of mineral nutrients by leaves, developed a new type of light rare earth foliar solid fertilizer based on the new mechanism, and proposed a series of protection plans for this application.

[0029] In a first typical embodiment of the present application, a light rare earth foliage solid fertilizer is provided. The light rare earth foliage solid fertilizer includes a trivalent light rare earth element, and the mass content of the trivalent light rare earth element is 0.15% to 1.2%.

[0030] The trivalent light rare earth elements (trivalent LREEs or LREE(III)) in the light rare earth foliar solid fertilizer include any one or more of La, Ce, Pr, Nd, Sm, or Eu. The trivalent light rare earth elements in the fertilizer can be provided by any substance containing the above elements in a stable valence state, preferably a water-soluble substance.

[0031] In the present study, the inventors discovered that when fertilizers containing rare earth elements (LREEs) (III) are sprayed, they induce the activation of a cascade of endocytosis and transcytosis in the trichome-plating cell epidermis of plant leaves. This cascade of endocytosis and transcytosis begins with the branching of the trichome cells (protrusions) and consists of multiple, sequential, six-step endocytosis-transcytosis reactions. The first six-step endocytosis-transcytosis occurs in the epidermal trichome cells, starting from their (protrusion) branches. The six steps include: invagination of the epidermal trichome cell (protrusion) plasma membrane, vesicle formation, vesicle migration to the trichome cell base, vesicle anchoring at the basal plasma membrane, complete fusion of the anchored vesicle with the basal plasma membrane, and vesicle release of its contents outside the plasma membrane of the plating cell (connected to the trichome). Subsequently, the second six-step endocytosis-transcytosis reaction occurs in the plating cell connected to the trichome cell. Subsequently, the third, fourth, fifth, and so on, six steps of endocytosis-transcytosis occur sequentially in more plated cells. This continuous six-step endocytosis-transcytosis process is defined as a cascade of endocytosis-transcytosis. This theoretical basis is first discovered in this application, which also finds that relatively low concentrations of LREE(III) can induce the opening of this new transport channel.

[0032] Based on the aforementioned theoretical foundation, once the endocytosis-transcytosis cascade is activated, mineral nutrients are absorbed and transported into leaf cells in large quantities. When the aforementioned micronutrient fertilizer is sprayed onto leaves during the seedling stage, the leaves activate a new, precise absorption and transport pathway for mineral nutrients, improving their efficiency, thereby promoting leaf and root growth and development, and increasing plant yield. In other words, the aforementioned light rare earth foliar solid fertilizer can be used to enhance foliar mineral nutrient absorption.

[0033] In the above-mentioned light rare earth foliar solid fertilizer, the mass content of LREE (III) element includes but is not limited to 0.15%, 0.3%, 0.45%, 0.6%, 0.75%, 0.9%, 1.05% or 1.2%.

[0034] In a preferred embodiment, the light rare earth foliar solid fertilizer also contains mineral nutrient elements, and the mineral nutrient elements include one or more of N element, P element, K element, S element, Mg element, Ca element, Mn element, Zn element, Cu element, Fe element, Cl element, B element or Mo element.

[0035] The fertilizer further contains mineral nutrients. By using trivalent LREEs to activate precise absorption and transport pathways for these nutrients, the nutrients in the fertilizer can be absorbed into leaf cells, promoting plant growth. The mineral nutrients in the fertilizer can be provided by any substance containing these elements. Preferably, the mineral nutrients are provided by soluble compounds.

[0036] In a preferred embodiment, the light rare earth foliar solid fertilizer comprises the following: the mass content of the N element is 10% to 20%, the mass content of the P element is 5% to 10%, the mass content of the K element is 20% to 30%, the mass content of the S element is 20% to 30%, the mass content of the Mg element is 4% to 5%, the mass content of the Ca element is 15% to 25%, the mass content of the Mn element is 0.01% to 0.02%, the mass content of the Zn element is 0.01% to 0.02%, the mass content of the Cu element is 0.001% to 0.002%, the mass content of the Fe element is 0.2% to 0.4%, the mass content of the Cl element is 1% to 3%, the mass content of the B element is 0.02% to 0.04%, and the mass content of the Mo element is 0.0005% to 0.001%.

[0037] In a second typical embodiment of the present application, a light rare earth foliar liquid fertilizer is provided. The light rare earth foliar liquid fertilizer includes an aqueous solution of a trivalent light rare earth element, and the concentration of the trivalent light rare earth element is 3.6 μM to 30 μM.

[0038] The above-mentioned light rare earth foliar liquid fertilizer is a form of use of this type of fertilizer. It can be obtained by dissolving the above-mentioned light rare earth foliar solid fertilizer in water, or it can be directly produced and sold in the form of liquid fertilizer. In the light rare earth foliar liquid fertilizer of this application, the concentration of trivalent light rare earth elements is much lower than the amount used for rare earth elements in the prior art, which has the effect of "small amount and significant effect", and can change people's traditional concept of considering REEs (rare earth elements) as large-dose fertilizers. Compared with traditional technologies, while improving the absorption efficiency and yield of mineral nutrients in plant leaves, the dosage of REEs is significantly reduced, thereby improving the safety of agricultural food. In addition, in this technology, the mixture of 16 REEs is adjusted to a pure single (i.e., La, Ce, Pr, Nd, Sm or Eu) or mixed (i.e., two or more of La, Ce, Pr, Nd, Sm or Eu) LREEs. The total concentration of trivalent light rare earth elements only needs to meet the requirements, and the content of each specific element is not required. This type of fertilizer can reduce the use of rare earth elements (REEs), prevent the accumulation of HREEs (heavy rare earth elements) in plants, and improve agricultural food safety. In particular, based on the discovery of a new principle for the precise absorption and transport of nutrient elements, the use of trace amounts of trivalent light rare earth elements (LREEs) unlocks the ability of leaf epidermal trichomes to absorb and transport mineral nutrients, significantly improving the absorption efficiency of foliar fertilizers and crop yields. This light rare earth foliar liquid fertilizer can be used to enhance foliar absorption of mineral nutrients.

[0039] In the above-mentioned light rare earth foliar liquid fertilizer, the concentration of trivalent light rare earth elements includes but is not limited to 3.6 μM, 4 μM, 5 μM, 10 μM, 15 μM, 20 μM, 25 μM or 30 μM.

[0040] In a preferred embodiment, the light rare earth foliar solid fertilizer also contains mineral nutrient elements, and the mineral nutrient elements include one or more of N element, P element, K element, S element, Mg element, Ca element, Mn element, Zn element, Cu element, Fe element, Cl element, B element or Mo element.

[0041] In a preferred embodiment, in the light rare earth foliar liquid fertilizer, the concentration of the N element is 0.05mM~0.11mM, the concentration of the P element is 0.6mM~1.3mM, the concentration of the K element is 1.8mM~3.1mM, the concentration of the S element is 2.2mM~3.7mM, the concentration of the Mg element is 0.58mM~0.82mM, the concentration of the Ca element is 1.3mM~2.5mM, the concentration of the Mn element is 0.6μM~1.5μM, the concentration of the Zn element is 0.5μM~1.2μM, the concentration of the Cu element is 0.06μM~0.13μM, the concentration of the Fe element is 12μM~28μM, the concentration of the Cl element is 0.1mM~0.3mM, the concentration of the B element is 6.5μM~14.8μM, and the concentration of the Mo element is 0.02μM~0.04μM.

[0042] In a preferred embodiment, the pH of the light rare earth foliar liquid fertilizer is 6.0-6.8.

[0043] In the prior art, in order to make the elements in REEs foliar fertilizers exist in the form of ions (i.e., bioavailable state), the pH of most REEs foliar fertilizers is adjusted to 4.0, causing plants to suffer from the acid damage caused by low pH, such as burn spots on leaves and inhibition of photosynthesis, which in turn affects the growth-promoting effect of REEs foliar fertilizers. The pH value of the above-mentioned light rare earth foliar liquid fertilizer is adjusted to 6.0-6.8, which avoids plant damage caused by excessive acidity and is beneficial to increasing crop yields. Within this pH range, each element exists in the form of a colloid rather than an ionic form. The new mechanism of activation of nutrient element absorption and transport channels in plants discovered by the above-mentioned inventors shows that rare earth elements in this physical state can be better absorbed and utilized by plants than rare earth elements in an ionic state, thereby inducing the opening of new channels for nutrient element absorption and transport in plants. Light rare earth foliar liquid fertilizer with a pH of 6.0-6.8 can not only protect plant leaves and prevent plants from being corroded by acidic fertilizers, but also open the transport channels in plants, greatly improving the plant's absorption of mineral nutrients. It can also better adhere to the leaves, increase the absorption time on the leaf surface, shorten the absorption time, and further improve the absorption efficiency of mineral nutrients.

[0044] In a third typical embodiment of the present application, a method for increasing the plant's ability to absorb mineral nutrients is provided, the method comprising: spraying the above-mentioned light rare earth foliar liquid fertilizer or the liquid fertilizer prepared from the above-mentioned light rare earth foliar solid fertilizer above the plant leaves; the amount of spraying is limited to the amount that does not drop from the plant leaves; above the plant leaves includes 10 cm-2 m directly above the plant leaves.

[0045] The method for dissolving the above-mentioned light rare earth foliage solid fertilizer to obtain liquid fertilizer includes: dissolving 350-400 mg of the above-mentioned light rare earth foliage solid fertilizer in 1L of water, stirring evenly to prepare a solution, and then using hydrochloric acid (preferably 1 mol / L) and sodium hydroxide (preferably 1 mol / L) as acid-base regulators to adjust the pH to 6.0-6.8, thereby obtaining the corresponding liquid fertilizer, which is the above-mentioned light rare earth foliage liquid fertilizer.

[0046] By spraying the liquid fertilizer on the leaves of plants using an electric ultra-low volume sprayer, an agricultural flying sprayer or other liquid spraying tools, fertilizing the plants can be achieved, thereby improving the plants' ability to absorb mineral nutrients and promoting plant growth. The operation is simple and requires less fertilizer.

[0047] The above-mentioned “increasing the ability of plants to absorb mineral nutrients” refers to increasing the mineral nutrient absorption efficiency of plants by at least 5%, preferably increasing the absorption efficiency by at least 10%.

[0048] In a preferred embodiment, the spraying time is from the time when the first true leaf of the plant is fully expanded to the time when the fourth true leaf is fully expanded.

[0049] In the above method, the fertilizer is sprayed earlier, when the first true leaf is fully expanded. This promotes the absorption of mineral nutrients by plant leaves in the early stages of plant growth and development, thereby increasing chlorophyll a content, enhancing photosynthesis, improving root and leaf growth, and promoting dry matter accumulation. This prevents the subsequent low absorption efficiency of mineral nutrients due to the thick waxy and mineral layers surrounding the leaf epidermal trichomes and the presence of a thick waxy layer on the leaf epidermis. Applying foliar fertilizers at this time also makes it difficult to achieve good results. However, rare earth fertilizers in the prior art, due to their high concentration and strong acidity, can only be applied after the third true leaf has formed, missing the critical early stage of plant growth and development.

[0050] In a fourth typical embodiment of the present application, there is provided an application of the above-mentioned light rare earth foliar solid fertilizer, the above-mentioned light rare earth foliar liquid fertilizer, or the above-mentioned method for increasing the plant's ability to absorb mineral nutrients in plant cultivation.

[0051] In a preferred embodiment, the plants include plants with pubescent hairs on their leaves; more preferably, they include, but are not limited to, grain crops or vegetable crops such as soybeans, rice, wheat, peanuts, or greens. The newly discovered absorption and transport mechanism is prevalent in the leaves of plants with pubescent hairs. The light rare earth foliar solid fertilizer, light rare earth foliar liquid fertilizer, or the aforementioned method can be applied to a variety of plants to promote the absorption of mineral nutrients by plant leaves, increase chlorophyll a content, enhance photosynthesis, improve root and leaf growth, promote dry matter accumulation, and increase yield.

[0052] The beneficial effects of the present application will be further explained in detail below with reference to specific embodiments.

[0053] Example 1

[0054] Prepare a light rare earth foliar liquid fertilizer containing 5 μM LREE(III) and the following mineral nutrients: 0.08 mM N, 0.9 mM P, 2.5 mM K, 2.9 mM S, 0.7 mM Mg, 1.9 mM Ca, 1.1 μM Mn, 0.9 μM Zn, 0.1 μM Cu, 20 μM Fe, 0.2 mM Cl, 10.5 μM B, and 0.03 μM Mo. Adjust the pH to 6.5.

[0055] Example 2

[0056] A light rare earth foliar liquid fertilizer was prepared, wherein the LREE (III) concentration was 5 μM, the mineral nutrient element concentration was the same as in Example 1, and the pH value was adjusted to 4.0.

[0057] Example 3

[0058] A light rare earth foliar liquid fertilizer was prepared, wherein the LREE (III) concentration was 15 μM, the mineral nutrient element concentration was the same as that in Example 1, and the pH value was adjusted to 6.5.

[0059] Example 4

[0060] A light rare earth foliar liquid fertilizer was prepared, wherein the LREE (III) concentration was 15 μM, the mineral nutrient element concentration was the same as in Example 1, and the pH value was adjusted to 4.0.

[0061] Example 5

[0062] A light rare earth foliar liquid fertilizer was prepared, wherein the LREE (III) concentration was 30 μM, the mineral nutrient element concentration was the same as in Example 1, and the pH value was adjusted to 6.5.

[0063] Example 6

[0064] A light rare earth foliar liquid fertilizer was prepared, wherein the LREE (III) concentration was 30 μM, the mineral nutrient element concentration was the same as in Example 1, and the pH value was adjusted to 4.0.

[0065] Comparative Example 1

[0066] The difference between this comparative example and Example 1 is that clean water is used instead of water to prepare the light rare earth foliar liquid fertilizer.

[0067] Comparative Example 2

[0068] The difference between this comparative example and Example 1 is that LREE (III) is omitted; the rest is the same as Example 1.

[0069] Comparative Example 3

[0070] The difference between this comparative example and Example 1 is that mineral nutrients are omitted; the rest is the same as Example 1.

[0071] Test Example 1

[0072] This test example examined the process of nutrient transport from leaf epidermal trichome cells downward, the content of mineral nutrients in leaf cells and roots, and the final plant yield of the light rare earth foliar liquid fertilizers in Examples 1-6 and Comparative Examples 1-3. The specific test process and test results are as follows:

[0073] Four treatment groups were set up: a blank group, control group 1, control group 2, and an experimental group. Each treatment group was replicated three times. A light rare earth foliar liquid fertilizer was sprayed 10 cm to 1 m from the leaf surface when the first and third true leaves of rice, soybeans, wheat, peanuts, and green vegetables were fully expanded and at maturity. The blank control group was sprayed with water from Comparative Example 1, control group 1 was sprayed with the mineral nutrients from Comparative Example 2, control group 2 was sprayed with the LREE(III) from Comparative Example 3, and the experimental groups were sprayed with the nutrients from Examples 1 to 6. After spraying, the dynamic processes of endomembrane transport and mineral nutrient absorption and transport were simultaneously observed using dual fluorescence labeling and rotating disk laser scanning confocal fluorescence microscopy. The mineral nutrient content and LREE(III) content in leaf cells and roots were measured using inductively coupled plasma mass spectrometry. Chlorophyll a fluorescence imaging system, a portable photosynthetic meter, a leaf area meter, and a root analysis system were used to measure chlorophyll a content, photosynthesis rate, and leaf and root growth indicators. After the plants matured, yield was measured.

[0074] The test results are shown in Figures 1, 2 and 3. Figure 1 shows the results of spraying light rare earth foliar liquid fertilizer on plant leaves with Zn 2+ As a proxy for mineral nutrients in fertilizers, dynamic images of rotating disk laser scanning confocal fluorescence microscopy were used to examine the pathways by which mineral nutrients enter the plant body after foliar application of light rare earth liquid fertilizer. Figure 2 shows the mineral nutrient content, chlorophyll a content, net photosynthesis rate, total leaf area, and total root length in leaf cells and roots after application of light rare earth liquid fertilizer to plants. Figure 3 shows crop yield (seed weight per plant) after light rare earth liquid fertilizer application.

[0075] Results showed that applying LREE foliar liquid fertilizer when the first true leaf was fully expanded activated a cascade of endocytosis and transcytosis of nutrients and minerals, starting from the trichome protrusions and then the plating cells. This initiated a new mode of transcellular transport of mineral nutrients, resulting in plant mineral nutrient absorption efficiency far exceeding that of mineral nutrient fertilizers without LREE(III). The enhanced nutrient absorption efficiency of LREE foliar liquid fertilizer applied when the first true leaf was fully expanded was stronger than that applied when the third true leaf was fully expanded. The enhanced nutrient absorption efficiency of LREE foliar liquid fertilizer applied at pH 6.5 was stronger than that of LREE foliar liquid fertilizer applied at pH 4.0. LREE foliar liquid fertilizer activated this new mode of efficient nutrient absorption by plant leaves, leading to a simultaneous increase in mineral nutrient content in leaves and roots, as well as increased chlorophyll a content and photosynthetic rate, resulting in higher yields. For soybeans, the total mineral nutrient content increases by 15% to 35%, and the average yield increases by 10% to 35%; for rice, the total mineral nutrient content increases by 10% to 25%, and the average yield increases by 10% to 25%; for wheat, the total mineral nutrient content increases by 15% to 40%, and the average yield increases by 15-35%; for green vegetables, the total mineral nutrient content increases by 20% to 30%, and the average yield increases by 20-35%. A comparison of prior art reports on the application of light rare earth foliar liquid fertilizers to 50 plants (including but not limited to soybeans, rice, wheat, peanuts, rapeseed, and horseradish) revealed that the application of this technology increased mineral nutrient absorption efficiency and yield by at least 10% compared to prior art, and the LREE(III) application rate was lower than the commonly used rate, avoiding waste of rare earth resources and pollution of plants and soil.

[0076] Test Example 2

[0077] This test example tests the physical properties of the light rare earth foliar liquid fertilizer in Examples 1-6 and Comparative Examples 1-3. The specific test process and test results are as follows:

[0078] Four sample groups were prepared: a blank group, a control group 1, a control group 2, and an experimental group. Each sample group was tested three times. The blank group received the water from Comparative Example 1, Control Group 1 received the mineral nutrients from Comparative Example 2, Control Group 2 was sprayed with the LREE(III) from Comparative Example 3, and the experimental groups received the light rare earth foliar liquid fertilizers from Examples 1-6. After sample preparation, the distribution of LREE(III) and nutrient elements in the samples was measured using a digital camera; the adhesion work of the samples on plant leaf surfaces was measured using a surface tensiometer; and the absorption time of the samples by plant leaf trichomes was measured using a video optical contact angle meter.

[0079] Figure 4 shows a sample's Tyndall effect test. Figure 5 shows the adhesion work of a light rare earth foliar liquid fertilizer on a plant leaf surface, demonstrating its adhesion. Figure 6 shows the absorption time of a light rare earth foliar liquid fertilizer on leaf trichomes. This absorption time was captured by capturing the dynamic absorption process of a droplet on a trichome surface with a camera, measuring the time it takes for the droplet to land and disappear.

[0080] Results showed that a light rare earth foliar fertilizer with a pH of 6.5 exhibited a colloidal state, exhibiting stronger adhesion to plant leaf surfaces and faster absorption than mineral nutrient fertilizers without light rare earths or foliar fertilizers containing only light rare earths. The light rare earth foliar fertilizer with a pH of 6.5 exhibited a stronger Tyndall effect and stronger adhesion to plant leaf surfaces than that with a pH of 4.0, and was absorbed faster by leaf trichomes than that with a pH of 4.0.

[0081] From the above description, it can be seen that the above-mentioned embodiments of the present invention achieve the following technical effects: The present invention provides a technology for activating the cascade endocytosis-transcytosis of plant leaf epidermal trichome cells and plating cells based on trace light rare earth elements (LREEs), thereby achieving efficient absorption of nutrients by plants, and relates to the field of plant nutrition technology. This technology induces plant leaves to accurately and efficiently absorb mineral nutrients by spraying a foliar fertilizer containing trace amounts (3.6μM to 30μM) of trivalent LREEs (i.e., the above-mentioned light rare earth foliar liquid fertilizer) evenly above the plant leaves. The theoretical basis and technology of this invention are that during the seedling stage of plants, when the light rare earth foliar liquid fertilizer is sprayed on the leaves, LREEs (III) initiate the absorption and transport of nutrients from the trichome cell protrusions through the cascade endocytosis-transcytosis of the trichome cell-plating cell, thus opening up a new mode of transcellular transport of mineral nutrients, enabling the precise absorption and transport of mineral nutrients into leaf cells. The light rare earth foliar liquid fertilizer is composed of LREEs (III) and mineral nutrients. The LREEs are any compound of La, Ce, Pr, Nd, Sm, and Eu, or any mixture containing LREEs and any of their stable valence states; the mineral nutrients are provided in the form of any substance containing N, P, K, S, Mg, Ca, Mn, Zn, Cu, Fe, Cl, B, and Mo. The present invention is widely applicable to all crops with trichomes on their leaves, such as rice, soybeans, wheat, peanuts, and green vegetables. When used when the first (or subsequent) true leaves of a plant are fully expanded, this technology can induce the plant leaves to absorb mineral nutrients accurately and efficiently, thereby increasing crop yields. The average nutrient absorption efficiency is increased by 12-40%, and the average yield is increased by 10-35%.

[0082] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A light rare earth foliar solid fertilizer, characterized in that: The light rare earth foliage solid fertilizer includes trivalent light rare earth elements, The mass content of the trivalent light rare earth element is 0.15% to 1.2%.

2. The light rare earth foliage solid fertilizer according to claim 1, characterized in that The light rare earth foliage solid fertilizer also contains mineral nutrient elements. The mineral nutrient elements include one or more of nitrogen, phosphorus, potassium, sulfur, magnesium, calcium, manganese, zinc, copper, iron, chlorine, boron or molybdenum.

3. The light rare earth foliage solid fertilizer according to claim 2, characterized in that In the light rare earth foliage solid fertilizer, The mass content of the nitrogen element is 10% to 20%, and the mass content of the phosphorus element is 5% to 10%. The mass content of the potassium element is 20% to 30%, and the mass content of the sulfur element is 20% to 30%. The mass content of the magnesium element is 4% to 5%, and the mass content of the calcium element is 15% to 25%. The mass content of the manganese element is 0.01% to 0.02%, and the mass content of the zinc element is 0.01% to 0.02%. The mass content of the copper element is 0.001% to 0.002%, and the mass content of the iron element is 0.2% to 0.4%. The mass content of the chlorine element is 1% to 3%, and the mass content of the boron element is 0.02% to 0.04%. The mass content of the molybdenum element is 0.0005% to 0.001%.

4. A light rare earth foliar liquid fertilizer, characterized in that: The light rare earth foliage liquid fertilizer comprises an aqueous solution of a trivalent light rare earth element, and the concentration of the trivalent light rare earth element is 3.6 μM to 30 μM.

5. The light rare earth foliage liquid fertilizer according to claim 4, characterized in that The light rare earth foliage liquid fertilizer also contains mineral nutrient elements. The mineral nutrient elements include one or more of nitrogen, phosphorus, potassium, sulfur, magnesium, calcium, manganese, zinc, copper, iron, chlorine, boron or molybdenum.

6. The light rare earth foliage liquid fertilizer according to claim 5, characterized in that In the light rare earth foliar liquid fertilizer, The concentration of the nitrogen element is 0.05mM to 0.11mM, the concentration of the phosphorus element is 0.6mM to 1.3mM, The concentration of the potassium element is 1.8mM to 3.1mM, and the concentration of the sulfur element is 2.2mM to 3.7mM. The concentration of the magnesium element is 0.58mM to 0.82mM, and the concentration of the calcium element is 1.3mM to 2.5mM. The concentration of the manganese element is 0.6 μM to 1.5 μM, and the concentration of the zinc element is 0.5 μM to 1.2 μM. The concentration of the copper element is 0.06 μM to 0.13 μM, and the concentration of the iron element is 12 μM to 28 μM. The concentration of the chlorine element is 0.1mM to 0.3mM, and the concentration of the boron element is 6.5μM to 14.8μM. The concentration of the molybdenum element is 0.02 μM to 0.04 μM.

7. The light rare earth foliage liquid fertilizer according to any one of claims 4 to 6, characterized in that The pH value of the light rare earth foliage liquid fertilizer is 6.0-6.

8.

8. A method for increasing a plant's ability to absorb mineral nutrients, characterized in that: The method comprises: spraying the liquid fertilizer prepared by the light rare earth foliage liquid fertilizer according to any one of claims 4 to 7 or the liquid fertilizer prepared by the light rare earth foliage solid fertilizer according to any one of claims 1 to 3 on the leaves of the plant; The spraying amount is limited to the amount that droplets do not drip from the leaves of the plant; The area above the plant leaf surface includes 10 cm to 2 m directly above the plant leaf surface.

9. The method according to claim 8, characterized in that The spraying time is from the time when the first true leaf of the plant is fully expanded to the time when the fourth true leaf is fully expanded.

10. Use of the light rare earth foliage solid fertilizer according to any one of claims 1 to 3, or the light rare earth foliage liquid fertilizer according to any one of claims 4 to 7, or the method for increasing the absorption capacity of plants for mineral nutrients according to claim 8 or 9 in plant cultivation.

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