JP7637542B2 - Composition for improving phosphorus use efficiency in plants and use thereof - Google Patents

Description

The present invention relates to a composition for improving phosphorus uptake efficiency and/or phosphorus utilization efficiency in plants, and its use.

Establishing technology to improve the productivity of agricultural crops and useful plants is an urgent task as one of the solutions to the ongoing food problem on a global scale. Efficient fertilization during plant cultivation is the key to solving this problem. The three major nutrients for plants are nitrogen, phosphorus, and potassium, and these nutrients are essential for plant cultivation.

The appropriate amount of phosphorus fertilizer, one of the three major nutrients, is determined by the phosphate fixing capacity of the soil to which it is applied. The phosphate fixing capacity of soil is indicated by the phosphate absorption coefficient as an index in soil analysis. It is also known that applying more than the required amount of phosphorus fertilizer does not increase plant yields, so the amount of phosphorus fertilizer to be applied must be determined taking into account the soil's phosphate absorption coefficient and the available phosphate content in the soil.

JP 2004-352679 A JP 2009-165494 A JP 2008-120815 A International Publication WO01/80638 Pamphlet International Publication WO2008/072602 Pamphlet International Publication WO2009/063806 Pamphlet International Publication WO2013/088956 Pamphlet JP 2001-288011 A

There are environmental issues surrounding phosphorus, such as concerns over the global depletion of phosphate rock, the source of phosphorus, and the excessive enrichment of soil with phosphorus due to phosphorus fertilization. There are also economic issues, such as the costs involved in fertilization.

As mentioned above, the amount of phosphorus available to plants varies depending on the soil's phosphorus fixing capacity, so plant growth and yields are affected by the properties of each soil, and the amount of phosphorus fertilizer applied to the soil also varies greatly.

In light of the above, there is a need to develop a new fertilization system that is effective in protecting the environment, reducing costs, and achieving efficient plant cultivation with less phosphorus fertilizer application.

The present invention has been made in consideration of the above problems, and its purpose is to develop a technology for improving the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants, and to provide a technology for easily and efficiently producing plants with improved phosphorus absorption efficiency and/or phosphorus utilization efficiency.

The present inventors have conducted intensive research to solve the above problems, and as a result, they have succeeded in dramatically improving the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants by growing plants in the presence of glutathione. It has been found that glutathione can be used to efficiently redifferentiate callus in a short period of time (Patent Documents 1 and 2, etc.), to regulate cell or organ differentiation (Patent Documents 3 and 4, etc.), to improve the harvest index of plants (Patent Document 5, etc.), to improve the sugar content of plants (Patent Document 6, etc.), and to increase the amino acid content of plants (Patent Document 7). It has also been reported that a substance that improves the absorption of at least one of nitrate ions, phosphate ions, and potassium ions by 10% or more has been used as a plant activator, and it has been reported that fatty acids or their derivatives, alcohols or their derivatives, etc. actually contribute to improving the absorption of phosphate ions through experiments, but the effect of proteins or their derivatives as plant activators has not been confirmed (Patent Document 8). In particular, there has been no report to date that the application of glutathione improves the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants. Furthermore, the fact that the phosphorus utilization efficiency of plants, particularly in phosphorus-poor soils, can be easily increased is an exceptionally remarkable effect that goes beyond the range that would be predicted by a person skilled in the art.

In order to solve the above problems, the present invention includes any one of the following aspects.
[1] A composition for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency in a plant, comprising a phosphate absorption enhancer, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.
[2] The composition described in [1], which is a composition for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants in phosphorus-poor soil or under phosphorus-poor conditions.
[3] The composition according to [1] or [2], wherein the glutathione or a derivative thereof is selected from the group consisting of oxidized glutathione, reduced glutathione, homoglutathione, carboxypropyl glutathione, dicarboxyethyl glutathione, and esters thereof.
[4] The composition according to any one of [1] to [3], further comprising a phosphorus compound or a derivative thereof, or used in combination with a phosphorus compound or a derivative thereof.
[5] The composition according to [4], wherein the phosphorus compound or a derivative thereof is selected from the group consisting of superphosphate, trihydrogen superphosphate, fused phosphorus, burnt phosphorus, ammonium phosphate, phosphorous acid and organic phosphorus.

[6] A method for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency in a plant, comprising a step of cultivating the plant in the presence of a phosphate absorption enhancer, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.
[7] A method for reducing the amount of phosphorus fertilizer applied to a plant, comprising the steps of cultivating the plant in the presence of a phosphate absorption enhancer and applying the phosphorus fertilizer to the plant, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.
[8] A method for growing plants in phosphorus-deficient soil, comprising the step of cultivating a plant in the phosphorus-deficient soil in the presence of a phosphate absorption enhancer, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.
[9] The method according to [8], further comprising the step of applying a phosphorus compound or a derivative thereof to the plant.
[10] A method for producing a plant with improved phosphorus absorption efficiency and/or phosphorus utilization efficiency, comprising the steps of cultivating a plant in the presence of a phosphate absorption enhancer and measuring the phosphorus absorption efficiency and/or phosphorus utilization efficiency in the plant, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.
[11] The method described in [10], further comprising a step of selecting, from among the plants cultivated with the application of the phosphate absorption enhancer, plants having improved phosphorus absorption efficiency and/or phosphorus utilization efficiency compared to plants cultivated in the absence of the phosphate absorption enhancer.
[12] The method according to [6], [7] or [10], wherein the step of cultivating the plant comprises cultivating the plant in phosphorus-deficient soil or under phosphorus-deficient conditions.
[13] The method according to any of [6] to [12], wherein the glutathione or a derivative thereof is selected from the group consisting of oxidized glutathione, reduced glutathione, homoglutathione, carboxypropyl glutathione, dicarboxyethyl glutathione, and esters thereof.

[14] Glutathione or a derivative thereof for use as a phosphate absorption enhancer in plants.
[15] Glutathione or a derivative thereof for use in improving phosphorus absorption efficiency and/or phosphorus utilization efficiency in plants.

The present invention can be used to improve the phosphorus absorption efficiency of plants and the phosphorus utilization efficiency of plants, particularly in phosphorus-poor soil. Furthermore, it is possible to easily and efficiently create plants with improved phosphorus absorption efficiency and/or phosphorus utilization efficiency.

FIG. 1 shows the results of investigating the effect of fertilization of oxidized glutathione on the growth of Arabidopsis thaliana in soils with different phosphate contents. 1 shows the results of investigating the effect of fertilization of oxidized glutathione on the phosphate content in the leaf blade of Arabidopsis thaliana, showing the phosphate content in the leaf blade per mg of fresh weight of Arabidopsis thaliana. 1 shows the results of investigating the effect of fertilization of oxidized or reduced glutathione on the phosphorus compound content in Arabidopsis thaliana leaf blades, and shows the phosphorus compound content in the leaf blades per gram of dry weight of Arabidopsis thaliana. FIG. 1 shows the results of investigating the effect of fertilization of oxidized glutathione on the growth of Garland chrysanthemum in soil fertilized with various amounts of phosphate. FIG. 1 shows the results of investigating the effect of fertilization of oxidized glutathione on the fresh weight of garland chrysanthemum in soil fertilized with various amounts of phosphate. FIG. 1 shows the results of investigating the effect of fertilization of oxidized glutathione on the growth of Garland chrysanthemum in soil fertilized with a lower amount of phosphate than P1. FIG. 1 shows the phosphate content in the leaf blade per mg of fresh weight of Garland Chrysanthemum. FIG. 1 shows the phosphate content and phosphorus utilization efficiency per Garland chrysanthemum individual.

[Terminology explanation]
As used herein, the term "phosphorus" refers to any phosphorus compound and its derivatives, including both phosphorus compounds in a form that can be absorbed and utilized by plants and phosphorus compounds in a form that cannot be utilized by plants.

"Soil phosphorus" refers to the total phosphorus content in soil. Phosphate (H ₃ PO ₄ ) in soil exists in the form of different phosphate ions (H ₂ PO ₄ ^- , HPO ₄ ^2- , PO ₄ ^3- ) depending on the soil pH, and in the form of phosphorus compounds in which these phosphate ions are bound to cations in the soil. "Soil phosphorus" refers to the total amount of all these forms of phosphorus present in soil.

In this specification, the "phosphate absorption coefficient" refers to the amount (mg) of phosphoric acid (P ₂ O ₅ ) absorbed and fixed by 100 g of dry soil, and is an index showing the phosphate fixing power of soil.

Phosphate fixation occurs when cations of iron, aluminum, calcium, etc. in soil combine with phosphate anions to form poorly soluble compounds that are unavailable for plants to absorb and use, and the phosphate components are strongly adsorbed and fixed in the soil. The higher the phosphate absorption coefficient, the stronger the soil's phosphate fixing ability and the stronger the ability to make the phosphate components in the soil unavailable. The magnitude of the phosphate absorption coefficient is largely determined by the soil's inherent component characteristics. The appropriate amount of phosphorus fertilizer to be applied is determined according to the phosphate absorption coefficient of the target soil. Therefore, the amount of phosphorus fertilizer to be applied must be determined taking the phosphate absorption coefficient into consideration. It is known that the phosphate absorption coefficient varies greatly depending on the type of soil.

For example, alluvial soil and sandy loam have few clay minerals and therefore a low phosphate absorption coefficient, but volcanic soil, especially black soil, has a lot of clay minerals and a lot of active aluminum that dissolves in an acidic environment, so it has a high phosphate absorption coefficient. As an example, the phosphate absorption coefficient of typical black soil is over 1,500.

In this specification, "phosphorus-deficient soil" or "phosphorus-deficient conditions" refers to soil or conditions in which the amount of phosphorus in a form that can be absorbed by plants is low, limiting the phosphorus utilization of the soil or growing conditions by plants. It also includes phosphate-deficient soil or conditions in which phosphorus itself is deficient. It also includes soil or conditions in which the above-mentioned phosphate absorption coefficient is high and phosphate fixation occurs frequently, resulting in a low amount of available phosphate. Specific soils or conditions are described in detail below.

"Available phosphate" is the form of soil phosphate that can be absorbed by plants, and is also called available phosphate. The amount of available phosphate in soil can be calculated by extracting a portion of the phosphate in the soil with an appropriate solution using a method such as the Triogue method.

"Phosphorus utilization efficiency" is defined as the efficiency of biomass (target product) productivity per unit of phosphorus taken up by a plant. The efficiency of biomass (target product) productivity can be indicated, for example, by the harvest index per unit of phosphorus taken up by a plant. The harvest index means the ratio of the biomass amount of the harvested product to the total biomass amount. As shown in the examples, in the present invention, the use of a phosphate absorption enhancer increases the amount of biomass or harvest index in a plant per unit of phosphorus taken up by the plant, compared to when a phosphate absorption enhancer is not applied. In addition, in the present invention, the use of a phosphate absorption enhancer increases the amount of biomass or harvest index in a plant per unit of phosphorus taken up by a plant, even in phosphorus-poor soil or under phosphorus-poor conditions, compared to when a phosphate absorption enhancer is not applied.

Furthermore, "improving phosphorus utilization efficiency" in plants means the effect of improving phosphorus utilization efficiency compared to conditions in which the phosphate absorption enhancer of the present invention is not applied. In other words, it also intends the effect of improving the amount of biomass or harvest index relative to the amount of phosphate applied or absorbed compared to conditions in which the phosphate absorption enhancer of the present invention is not applied.

"Enhanced phosphate absorption" means that phosphate absorption from soil into the plant body is enhanced, and "phosphorus absorption efficiency" means the efficiency of phosphorus absorption from soil into the plant body. The phosphorus form in "phosphorus absorption" includes all phosphorus compounds in a form that can be absorbed and used by plants, but phosphorus in soil is usually absorbed by plants in the form of phosphorus. Therefore, "phosphorus absorption" can also be rephrased as "phosphate absorption". "Phosphate absorption enhancer" can also be rephrased as "phosphorus absorption enhancer". In addition, "phosphorus absorption" from soil into the plant body can be evaluated, for example, using the change in the phosphorus (or phosphorus compound) content in the plant body as an indicator. In other words, if the phosphorus content or phosphorus compound content of a plant body applied with a phosphate absorption enhancer is increased compared to a plant body without the application of a phosphate absorption enhancer, or if the phosphorus or phosphorus compound content per individual from the time of sowing to the time of sampling at each time point is higher than the samples sampled at different times from sowing, these can be considered to be "enhanced phosphorus absorption".

"Improving phosphorus absorption efficiency" means the effect of improving phosphorus absorption efficiency compared to conditions in which the phosphate absorption enhancer of the present invention is not applied. In other words, it also intends the effect of improving the amount of phosphorus per plant weight, i.e., the phosphorus content, compared to conditions in which the phosphate absorption enhancer of the present invention is not applied.

In this specification, the term "harvest index" refers to the ratio of the weight of the harvested crop to the weight of the entire plant. In other words, the ratio of the biomass of the harvested crop to the total biomass of the plant.

In this specification, the term "harvest product" refers to the parts of the plant that are used as food, such as the fruit in the case of a plant that is eaten for its fruit, the seeds in the case of a plant that is eaten for its seeds, the stems in the case of a plant that is eaten for its stems, the roots in the case of a plant that is eaten for its roots, the flowers in the case of a plant that is eaten for its flowers, and the leaves in the case of a plant that is eaten for its leaves, but also includes parts of the plant that are not used as food but contain the product of cultivation. Specifically, for example, in the case of a plant that is used for ornamental purposes, the harvest product includes the flowers, stems, leaves, roots, seeds, etc. that are objects of ornamental use.

In addition, in this specification, "improving the harvest index" refers to the effect of improving the harvest index compared to conditions in which the phosphate absorption enhancer of the present invention is not applied as fertilizer, and means increasing the ratio of the harvested biomass to the total biomass even under conventional standard fertilization conditions optimized to maximize the yield per unit area. Increasing the planting density improves the yield per unit area, but this effect saturates at a certain planting density. In this invention, "improving the harvest index" refers to the effect of increasing the ratio of the harvested biomass to the total biomass even under such planting conditions.

"Phosphorus fertilizer" refers to a fertilizer that contains phosphorus compounds and their derivatives and is commonly used in the art. Details of the phosphorus compounds and their derivatives that are included are described below.

"Reducing the amount of phosphorus fertilizer applied" refers to reducing the total amount of phosphorus fertilizer applied that is required while cultivating a plant, and specifically refers to reducing the total amount of phosphorus fertilizer applied compared to the conventional total amount of phosphorus fertilizer applied without application of the phosphate absorption enhancer of the present invention (for example, the total amount of phosphorus fertilizer applied calculated by the conventional fertilizer application calculation method that is determined from the phosphate absorption coefficient and available phosphate amount of the soil in which the plant is cultivated).

In this specification, "nutrient solution culture" or "hydroponic culture" refers to any cultivation method that provides plants with the nutrients and moisture they need to grow in the form of liquid fertilizer. In other words, it broadly includes both cultivation methods that use a medium (hereinafter also referred to as a support) to support the roots and those that do not.

[1. Composition for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency in plants]
The present invention provides a composition for improving phosphorus uptake efficiency and/or phosphorus utilization efficiency in plants, comprising a phosphate absorption enhancer, wherein the phosphate absorption enhancer is glutathione or a derivative thereof. In a preferred embodiment, the composition of the present invention is a composition for improving phosphorus uptake efficiency and/or phosphorus utilization efficiency in plants in phosphorus-deficient soil or conditions.

(Phosphate absorption enhancer)
As used herein, the term "phosphate absorption enhancer" refers to a substance capable of enhancing phosphorus absorption by plants, particularly in phosphorus poor soils or conditions, or capable of increasing the phosphorus content in plants, and is glutathione or a derivative thereof. In the present invention, the phosphate absorption enhancer is preferably a substance that is absorbed by plants and acts by contacting the plants.

As shown in the examples below, compared to plants grown under normal conditions or plants grown with ammonium nitrate, plants grown with oxidized glutathione or reduced glutathione showed significantly increased phosphorus absorption and phosphorus utilization efficiency. Furthermore, in the examples below, even in soil with a low phosphorus concentration, plant phosphorus absorption was enhanced, phosphorus utilization efficiency was improved, and plants took up sufficient phosphate for growth.

(Glutathione or its derivatives)
Glutathione, which has detoxification and antioxidant effects in vivo, is a tripeptide consisting of γ-Glu-Cys-Gly, and is a form for storing or transporting sulfur in plants. In the method of the present invention, glutathione or a derivative thereof applied to plants may be oxidized glutathione (hereinafter also referred to as "GSSG") or reduced glutathione (hereinafter also referred to as "GSH") or a derivative thereof. In the present specification, "oxidized glutathione" refers to, for example, a molecule in which two molecules of reduced glutathione are linked by a disulfide bond. Examples of glutathione derivatives include homoglutathione, carboxypropyl glutathione, and dicarboxyethyl glutathione. Esters of glutathione or the above derivatives are also included in the glutathione derivatives. In the present specification, glutathione or a derivative thereof includes salts thereof and anhydrous or hydrated forms thereof. Examples of salt forms of glutathione or its derivatives include, but are not limited to, ammonium salts, calcium salts, magnesium salts, sodium salts, lithium salts, potassium salts, etc. Examples of anhydrous or hydrated forms include, but are not limited to, 0-8 hydrates. That is, the glutathione or its derivatives used in the present invention may be a substance selected from the group consisting of oxidized glutathione, reduced glutathione, homoglutathione, carboxypropyl glutathione, dicarboxyethyl glutathione, and esters thereof.

The manufacturing conditions for the glutathione or its derivatives used in the present invention are not particularly limited, and they may be artificially synthesized or derived from natural products. In addition, the degree of purification may be high or low, and commercially available products may be used.

Glutathione or its derivatives may be in either reduced or oxidized form, but is preferably in the oxidized form.

GSH has the property of being easily oxidized. Therefore, glutathione may contain a mixture of GSH and GSSG.

The composition of the present invention may contain GSH as glutathione or a derivative thereof, and the GSH may be oxidized to GSSG during storage or use. The composition may also be in a form in which the GSH is oxidized to GSSG after application to a plant body.

The method for oxidizing GSH to GSSG is not particularly limited. For example, GSH can be easily converted to GSSG by air oxidation. GSH may also be converted to GSSG by any artificial method known in the art.

A research group including the present inventor has been conducting research into the mechanisms of plant germination, growth, and flowering, and has found that by cultivating callus induced from a part of a plant body in a regeneration medium containing glutathione, rooting can be promoted and regenerated plants can be obtained efficiently from the callus in a short period of time (Patent Documents 1 and 2, etc.), that by cultivating a plant using glutathione, the number of seeds and the number of flowers of the cultivated plant can be significantly increased, that by cultivating a plant body having a mutation in the synthesis function or response function of a plant hormone (e.g., gibberellin) using glutathione, the number of side buds can be significantly increased, and the number of flowers (pods) can be increased accordingly (Patent Document 5, etc.), that the sugar content of the plant body can be improved (Patent Document 6, etc.), and that the amino acid content of the plant can be increased (Patent Document 7, etc.). However, the use of glutathione or its derivatives as a phosphate absorption enhancer, i.e., to improve the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants, is a new use that is completely different from the conventional uses of the substance. Furthermore, the effect of obtaining plants with improved phosphorus absorption efficiency and/or phosphorus utilization efficiency was completely unpredictable from previous uses. Thus, the present invention was made based on a completely new discovery by the inventors.

(Composition)
In the application of the phosphate absorption enhancer of the present invention, glutathione or its derivatives as a compound may be used directly, or a composition containing glutathione or its derivatives may be used.The form of the phosphate absorption enhancer includes solid form and liquid form.It may also be in the form of a composition that contains at least glutathione or its derivatives as a component.

(Other ingredients and dosage forms)
Furthermore, the composition of the present invention may contain other ingredients as long as the effects of glutathione or its derivatives are not impaired.

The composition according to the present invention may contain a phosphate absorption enhancer other than glutathione or its derivatives. Examples of phosphate absorption enhancers other than glutathione or its derivatives include substances that increase the synthesis of glutathione or the amount of glutathione produced.

In one embodiment, the composition of the present invention further contains a phosphorus compound or a derivative thereof. In another embodiment, the composition of the present invention is used in combination with a phosphorus compound or a derivative thereof.

(Phosphorus compounds and their derivatives)
Generally, phosphoric acid is classified according to its solubility into water-soluble phosphoric acid (phosphate soluble in water), soluble phosphoric acid, and citric acid-soluble phosphoric acid (insoluble in water and soluble in 2% citric acid). Water-soluble phosphoric acid is fast-acting, whereas soluble phosphoric acid and citric acid-soluble phosphoric acid are slow-acting.

The phosphorus compound or its derivatives may be in the form of calcium phosphate (calcium superphosphate, calcium triphosphate, etc.; a mixture of water-soluble phosphoric acid and citrate-soluble phosphoric acid), fused phosphorus, burned phosphorus, burned phosphorus, ammonium phosphate (ammonium sulfate, potassium ammonium nitrate, ammonium chloride, etc.), phosphorous acid, organic phosphorus (animal-derived substances such as bone meal and fish meal), humic acid phosphorus, magnesia superphosphate, ammonium polyphosphate, potassium metaphosphate, calcium metaphosphate, magnesia phosphoric acid, Linstar (registered trademark) (J-CAM AGRI Co., Ltd.), and phosphate buffer solution. In one embodiment, the phosphorus compound or its derivatives are selected from the group consisting of calcium superphosphate, calcium triphosphate, fused phosphorus, burned phosphorus, ammonium phosphate, phosphorous acid, and organic phosphorus. From the viewpoint of increasing the phosphorus concentration while decreasing the hydrogen ion concentration (i.e., pH) in the soil, calcium phosphate (calcium superphosphate, calcium triphosphate, etc.) is preferable. Furthermore, soluble phosphates such as fused phosphorus are more preferable because they are less likely to be fixed in the soil and are more effective as fertilizers.

Examples of the phosphate buffer include phosphoric acid, potassium phosphate, sodium phosphate, ammonium phosphate, and mixtures thereof. Examples of the potassium phosphate include potassium phosphate, dipotassium hydrogen phosphate (K ₂ HPO ₄ ), and potassium dihydrogen phosphate (KH ₂ PO ₄ ). Examples of the sodium phosphate include sodium phosphate (Na ₃ PO ₄ ), disodium hydrogen phosphate (Na ₂ HPO ₄ ), and sodium dihydrogen phosphate (NaH ₂ PO ₄ ). Examples of the ammonium phosphate include ammonium phosphate ((NH ₄ ) ₂ PO ₄ ), diammonium hydrogen phosphate ((NH ₄ ) ₂ HPO ₄ , (ammonium phosphate)), and ammonium dihydrogen phosphate (NH ₄ H ₂ PO ₄ ).

In one example, the phosphorus compound contained in or used in combination with the composition of the present invention is a phosphate buffer consisting of a mixture of _disodium hydrogen phosphate _{( Na2HPO4} ) and sodium dihydrogen phosphate ( _NaH2PO4 ).

The amount of phosphorus compound or its derivative contained in the composition or used in combination is appropriately set depending on the target plant or soil to which it is applied, and is not particularly limited.

The composition of the present invention may further contain a nitrogen compound or a derivative thereof (urea, ammonium nitrate, ammonium magnesium nitrate, ammonium chloride, ammonium sulfate, ammonium phosphate, sodium nitrate, calcium nitrate, potassium nitrate, lime nitrogen, etc.), a potassium compound or a derivative thereof (potassium chloride, potassium sulfate, potassium sodium sulfate, magnesium potassium sulfate, potassium bicarbonate, potassium phosphate, etc.), and other components added to general fertilizers.

The composition of the present invention may further contain a conventionally known soil conditioner for adjusting the pH, EC (electrical conductivity) and moisture of the soil. Examples of such soil conditioners include pH adjusters such as hydrochloric acid, sulfuric acid and nitric acid, and moisturizing agents such as high molecular weight absorbent polymers. Note that EC (electrical conductivity) represents the total amount of water-soluble salts in the soil, and is an index of the amount of salts such as nitric acid and sulfuric acid dissolved in the soil solution. EC is an index of the salt tolerance of crops.

The composition of the present invention may be in a solid or liquid form. For example, the composition of the present invention may be dissolved in water or a conventionally known liquid carrier, and provided in the form of a liquid, emulsion, gel, or the like. Examples of such liquid carriers include, but are not limited to, aromatic hydrocarbons such as xylene; alcohols such as ethanol and ethylene glycol; ketones such as acetone; ethers such as dioxane and tetrahydrofuran; dimethylformamide, dimethyl sulfoxide, acetonitrile, and the like. The composition of the present invention may also be a solid agent, powder, or the like in which glutathione or a derivative thereof is supported on a solid carrier component. Examples of such solid carrier components include, but are not limited to, inorganic substances such as talc, clay, vermiculite, diatomaceous earth, kaolin, calcium carbonate, calcium hydroxide, white clay, and silica gel; and organic substances such as wheat flour and starch. The composition of the present invention may also be appropriately formulated with other auxiliary agents. Examples of such adjuvants include anionic surfactants such as alkyl sulfates, alkyl sulfonates, alkylaryl sulfonates, and dialkyl sulfosuccinates; cationic surfactants such as salts of higher aliphatic amines; nonionic surfactants such as polyoxyethylene glycol alkyl ethers, polyoxyethylene glycol acyl esters, polyoxyethylene glycol polyhydric alcohol acyl esters, and cellulose derivatives; thickeners such as gelatin, casein, and gum arabic; extenders, binders, and the like.

If necessary, at least one other plant growth regulator or phosphate absorption enhancer (e.g., benzoic acid, nicotinic acid, nicotinamide, pipecolic acid, etc.) can be blended into the composition to the extent that it does not impair the intended effect of the present invention. In addition, conventionally known fertilizers, including phosphorus fertilizers described below, may be blended into the composition.

(Formulation of Composition)
The dosage form of the composition of the present invention is not particularly limited, and may be in the form of a liquid, tablet, powder, or granule.

When used for the purpose of successfully preparing a solution containing a phosphate absorption enhancer, the composition of the present invention is preferably in the form of a tablet, powder or granules. And, it is preferable that the phosphate absorption enhancer is contained in the composition so that the final concentration of the phosphate absorption enhancer in the obtained solution is within the above-mentioned range.

By applying the phosphate absorption enhancer of the present invention, the phosphorus absorption efficiency per plant can be improved and/or the phosphorus utilization efficiency of the plant can be improved. In particular, by applying the phosphate absorption enhancer of the present invention, the phosphorus absorption efficiency per plant can be improved and/or the phosphorus utilization efficiency of the plant can be improved even in phosphorus-poor soil or under phosphorus-poor conditions. Therefore, efficient phosphorus fertilization can be realized by using the phosphate absorption enhancer. Furthermore, since the harvest index of the plant can be increased, not only can the production of food and biomass resources per unit area be increased, but it is also suitably applied to the cultivation of plants that can be used industrially and plants for increasing the production of the harvests obtained from them.

In addition, by applying the phosphate absorption enhancer of the present invention, the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants can be significantly increased even in phosphorus-poor soil or conditions, so that plants can grow well even in phosphorus-poor soil or conditions. Whether a certain soil or growth condition is phosphorus-poor soil or condition is determined based on the cultivated plants and cultivation conditions, and is therefore relative, but can be evaluated by a method for measuring the amount of phosphorus in a form that can be absorbed by plants in the soil, a method for calculating the phosphorus absorption coefficient in the soil, etc. For example, when the amount of phosphorus (or phosphorus) contained in conventional cultivation soil or conditions is used as a standard, soil or conditions containing 90% or less of that, for example, 90% to 1%, 75% to 1%, 50% to 1%, or 25% to 1% of phosphorus (or phosphorus) correspond to phosphorus-poor soil or conditions. Also included are examples of phosphorus poor soils known in the art, along with their phosphate absorption coefficients: humic volcanic ash soils (phosphate absorption coefficients of 2000 or more), volcanic ash soils (including Andosols) (phosphate absorption coefficients of 2000-1500 (Andosols have a phosphate absorption coefficient of 1500 or more)), diluvial soils (phosphate absorption coefficients of 1500-700), and alluvial soils (phosphate absorption coefficients of 700 or less).

The application method and application amount of the phosphate absorption enhancer are described in detail below in the section on methods for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency in plants.

2. Method for improving phosphorus absorption efficiency and/or phosphorus use efficiency in plants
The present invention provides a method for improving phosphorus uptake efficiency and/or phosphorus utilization efficiency of a plant, comprising the step of cultivating a plant in the presence of a phosphate absorption enhancer, the phosphate absorption enhancer being glutathione or a derivative thereof. In a preferred embodiment, the method of the present invention is a method for improving phosphorus uptake efficiency and/or phosphorus utilization efficiency of a plant in phosphorus-deficient soil or conditions, comprising the step of cultivating a plant in the presence of a phosphate absorption enhancer in phosphorus-deficient soil or conditions. The method will be described in detail below.

As for the phosphate absorption enhancer used in this method, those described in [1. Phosphate absorption enhancers] are preferably used. In other words, the phosphate absorption enhancer applied in this method may be applied in the form of a composition containing glutathione or a derivative thereof.

(Time of application of phosphate absorption enhancers)
The timing of application of the phosphate absorption enhancer of the present invention is not particularly limited, and the phosphate absorption enhancer may be applied under conditions in which the plant can constantly absorb the phosphate absorption enhancer, or may be applied under conditions in which the plant can absorb the phosphate absorption enhancer intermittently throughout the cultivation period, or may be applied only during a specific growth period. Examples of intermittent conditions include application at intervals of once or twice a week, or at intervals such as every transplantation (replanting).

By applying the phosphate absorption enhancer of the present invention intermittently, the amount of the phosphate absorption enhancer used can be reduced, and the cost of plant cultivation can be reduced. When applying the phosphate absorption enhancer of the present invention intermittently, it is preferable to apply it at a fixed time interval, but this is not limited, and it may be applied at an indefinite time interval. For example, the phosphate absorption enhancer of the present invention may be applied from the time when the seeds of the plant are sown. Specifically, when the phosphate absorption enhancer of the present invention is applied to a plant that will reach the harvest time about two months to a little less than half a year after sowing, it may be applied on the day of sowing, preferably from the day of sowing to four weeks after sowing, more preferably from the day of sowing to seven weeks after sowing, and even more preferably, it is applied periodically from the day of sowing to the day of harvest. In this case, the interval at which the phosphate absorption enhancer of the present invention is applied is not particularly limited, but is preferably once to four times a week, and more preferably two to three times a week.

The time interval for applying the phosphate absorption enhancer of the present invention is not particularly limited, and may be determined depending on the concentration of the phosphate absorption enhancer to be applied, the target plant, and the time of application of the phosphate absorption enhancer of the present invention. In general, when the target plant is a herbaceous plant, it is preferable to apply the enhancer once or twice a week, or at the same time as the top dressing period.

When seeds or fruits are envisaged as crops with improved phosphorus absorption efficiency and/or phosphorus utilization efficiency, it is preferable to apply the agent before or after the transition from the vegetative growth stage to the reproductive growth stage (including the transition from the vegetative growth stage to the reproductive growth stage), or during the subsequent flower bud formation stage, or when translocation to the target crop occurs. With this configuration, the phosphate absorption enhancer of the present invention is used only at specific times, thereby reducing the costs associated with plant cultivation.

When the phosphate absorption enhancer of the present invention is applied only at a specific time, the phosphate absorption enhancer of the present invention may be applied under conditions in which the plant can constantly absorb the phosphate absorption enhancer for a certain period of time during the specific time, or the phosphate absorption enhancer of the present invention may be applied under conditions in which the plant can absorb the phosphate absorption enhancer intermittently for a certain period of time during the specific time. By applying the phosphate absorption enhancer of the present invention intermittently for a certain period of time during the specific time, the cost of cultivating the plant can be further reduced.

(Application period of phosphate absorption enhancer)
The period of cultivating plant by applying phosphate absorption enhancer is not particularly limited, but when harvesting seeds or fruit, the period of applying the composition of the present invention or the phosphate absorption enhancer can be set based on the flowering period.For example, the composition of the present invention or the phosphate absorption enhancer can be applied at the bud stage, or after the petals fall, or the composition of the present invention or the phosphate absorption enhancer can be applied from the bud stage to the fruiting period, from the flowering period to the fruiting period, or from the petals fall to the fruiting period, or can be applied to inflorescence.

The application period is preferably from the start of cultivation to the time of harvest. When the composition is used by burying the adsorbent in the soil, the contact time with the plant body is longer, and the effect can be achieved with a smaller amount of application than when the composition is used as a liquid fertilizer in the soil or on the plant. For example, the composition may be applied continuously or intermittently from sowing, planting of cuttings or seedlings to harvest, or may be applied immediately after sowing, planting of cuttings or seedlings, or may be applied continuously or intermittently from the time of the parent plant, cutting growth or seedling growth of the plant body. In yet another embodiment, the phosphate absorption enhancer is applied in the top dressing process.

When seeds or fruits are harvested, the timing of application of the phosphate absorption enhancer of the present invention may be set based on the time when the flowers bloom. For example, the phosphate absorption enhancer of the present invention may be applied at the bud stage, or after the petals have fallen, or it may be applied from the bud stage to the time when the fruit ripens, from the flowering stage to the time when the fruit ripens, or from the time when the petals have fallen to the time when the fruit ripens, or it may be applied to the inflorescence.

(Application amount of phosphate absorption enhancer)
The amount of the phosphate absorption enhancer applied to the plant can be adjusted depending on its concentration, application method, and application target, but the amount can be defined by the total amount of the phosphate absorption enhancer actually applied to the plant. By applying the phosphate absorption enhancer to the plant, the growth of the entire plant and/or the growth of the harvested product can be promoted.

In addition, the amount of phosphorus accumulated in the plant body can be increased compared to when a phosphate absorption enhancer is not applied.

The concentration of the phosphate absorption enhancer applied during the cultivation period may be within a specific range. By applying the phosphate absorption enhancer to a plant, the growth of the plant can be promoted more effectively. In addition, the amount of phosphorus compounds and their derivatives accumulated in the plant body can be increased more effectively than when the phosphate absorption enhancer is not applied. The total amount of the phosphate absorption enhancer applied to the plant throughout the cultivation period can be converted into, for example, the weight of GSSG at the same molar concentration as the phosphate absorption enhancer used. For example, the amount of GSSG used during a 4-week cultivation period is preferably within the range of 12.5 mg to 300 mg per plant, and preferably within the range of 60 mg to 1450 mg per liter of soil. The period during which the plant is cultivated with GSSG is not particularly limited, but is preferably from 5 weeks (35 days) before harvesting to the time of harvesting.

(Method of application of solid phosphate absorption enhancer)
An example of a method for applying a solid form of a phosphate absorption enhancer is to mix the solid form of the phosphate absorption enhancer with a medium (support (e.g., soil)) for cultivating a plant.

When the phosphate absorption enhancer is applied to a plant in a solid form, the concentration of the phosphate absorption enhancer used is not particularly limited, but is preferably 0.1 mg to 4,000 mg, more preferably 0.4 mg to 800 mg per 1 L of medium volume, and even more preferably 1 mg to 100 mg per 1 L of medium volume. As an example, when oxidized glutathione (GSSG) is applied to a plant by applying it to a medium in the solid form of a 1% granule, it is preferably 0.01 g to 400 g per 1 L of medium volume, more preferably 0.04 g to 80 g per 1 L of medium volume, and even more preferably 0.1 g to 10 g per 1 L of medium volume. Such a concentration can further improve the growth rate of the plant.

When the phosphate absorption enhancer is applied as a tablet, powder, or granule, it may be contained in the medium used for growing plants, or when applied to plants grown hydroponically, it may be placed in water and gradually dissolved. It may also be provided as a solid agent to be dissolved in water, and dissolved in water when used.

(Method of application of liquid phosphate absorption enhancer)
Methods for applying the liquid phosphate absorption enhancer include wetting the whole or part of the plant, or a support on which the plant is to be planted, with a solution containing the phosphate absorption enhancer.

When provided in liquid form, the phosphate absorption enhancer of the present invention may be contained in a culture medium or the like used for growing plants, or may be sprayed, dripped, or applied to a part or the whole of a plant, such as a growing point, bud, leaf, or stem.

When the phosphate absorption enhancer is applied to a plant as a liquid composition, the concentration of the phosphate absorption enhancer is preferably 0.0002 mM to 7 mM, more preferably 0.0007 mM to 5 mM, 0.002 mM to 5 mM, 0.1 mM to 5 mM, 0.5 mM to 5 mM, even more preferably 1 mM to 5 mM, and even more preferably 2 mM to 5 mM. This range can further improve the growth of the plant produced. The liquid composition can be prepared by dissolving the phosphate absorption enhancer in a suitable solvent (e.g., water, etc.). The water can be any of deionized water, distilled water, reverse osmosis water, and tap water. The solvent can also contain components other than the phosphate absorption enhancer, such as various commercially available fertilizers and surfactants. The concentration of the phosphate absorption enhancer can be changed appropriately depending on the type of plant to which it is applied and the time of application.

For example, examples of methods for wetting a support for cultivating a plant with a solution containing a phosphate absorption enhancer include a method of sprinkling a solution containing a phosphate absorption enhancer from the top of the support, and a method of placing a support in a container filled with a solution containing a phosphate absorption enhancer and watering it from the bottom. When sprinkling water from the top of the support, the amount of water sprinkled from the top can be appropriately adjusted depending on the cultivation conditions such as the use conditions of the phosphate absorption enhancer and the pot volume. When sprinkling water from the top of the support, the amount of water sprinkled from the top can be appropriately adjusted depending on the cultivation conditions such as the use conditions of the phosphate absorption enhancer and the pot volume. For example, when assuming the use of 1 mM GSSG, 5 mL/time to 150 mL/time per individual is preferable, 8.5 mL/time to 100 mL/time is more preferable, and 20 mL/time to 50 mL/time is even more preferable. When watering from the bottom, it is sufficient that the solution containing the phosphate absorption enhancer is substantially uniformly wetted onto the support, but the amount and concentration of the liquid used in such a case can also be defined as the amount of phosphate absorption enhancer applied per unit of soil.

When the liquid composition is directly sprayed on the plant, the solution may be sprayed in mist form over a part or the whole plant using a sprayer or the like. The amount of solution to be sprayed is appropriately set depending on the concentration of the phosphate absorption enhancer in the solution. The number of sprays may be one or more, but it is preferable to spray at the start of cultivation. Furthermore, additional sprays may be made as appropriate during the cultivation period (e.g., every few days (2 to 7 days)) depending on the conditions of use of the phosphate absorption enhancer.

In addition, in the application of a phosphate absorption enhancer in a solid or liquid form, it is preferable that the medium or solution containing the phosphate absorption enhancer is supplied to the plant after the phosphate absorption enhancer is prepared within the above-mentioned concentration range, but it is sufficient that the phosphate absorption enhancer is mixed with the medium or solution at the stage of uptake by the plant. Therefore, the medium or solution not containing the phosphate absorption enhancer and the auxiliary agent may be supplied directly to the outer surface of the plant or supplied near the plant (to the support or soil) simultaneously or continuously. By using such a procedure, the plant can uptake the medium or solution mixed with the auxiliary agent. In addition, glutathione or a derivative thereof, or a composition containing it, may be mixed with a conventionally known fertilizer or a drug such as a plant hormone and given to the plant.

(Cultivation support and cultivation device)
In the cultivation step of the method of the present invention, a hydroponic cultivation apparatus and the like used for cultivating plants may be known. Also, a support and a nutrient solution used for cultivation may be known.

Soil can be used as the support. The type of soil is not particularly limited, but examples include soil in ordinary farm fields and horticultural soil (e.g., Kureha horticultural soil (Kureha)). Rock wool, gravel, or hydroballs, for example, may also be used. Soil such as coco peat (a soil conditioner made by piling and fermenting fiber fibers that form the shells of coconuts), pumice (volcanic pumice), peat moss, vermiculite, and perlite may also be used. Different types of soil may also be mixed in any ratio. When the support is soil, any type of soil may be used, and there are no limitations on the phosphorus content, phosphorus absorption coefficient, or available phosphorus amount in the soil.

In the case of hydroponic cultivation, the soil conditioner or soil can be filled into a small container such as a pot or a bag, the plant body can be transplanted therein, and the container or bag can be immersed in the nutrient solution to cultivate the plant.

The nutrient solution may be any known solution, and is not particularly limited. For example, the nutrient solution may be water, or an aqueous solution containing one or more components necessary for plant growth, such as nitrogen, phosphorus, potassium, and metal components. For example, an aqueous solution containing one or more components such as ammonia nitrogen, nitrate nitrogen, phosphoric acid (P ₂ O ₅ ), potassium (K ₂ O), magnesium (MgO), manganese (MnO), boron (B ₂ O ₂ ), iron (Fe), copper (Cu), zinc (Zn), and molybdenum (Mo) may be used.

When applying the phosphate absorption enhancer of the present invention during cultivation in this manner, the composition may be mixed with fertilizer and/or a chemical such as a plant hormone and then applied to the plant as described above. In this case, the timing for applying the mixture of the fertilizer and the composition is not particularly limited, and may follow the examples given above or a preferred timing for applying the fertilizer.

In view of the above, the present method, as one embodiment in which the fertilizer applied is a phosphorus fertilizer, is a method for improving the phosphorus absorption efficiency and/or phosphorus utilization efficiency of a plant, and includes a step of cultivating a plant in the presence of a phosphate absorption enhancer and a step of cultivating a plant in the presence of a phosphorus compound or a derivative thereof, in which the phosphate absorption enhancer is glutathione or a derivative thereof. In other words, in the method of the present invention, both the application of a phosphate absorption enhancer and the application of phosphorus fertilization to a plant may be performed.

The phosphorus compound or its derivative to be applied may be any of the phosphorus compounds or its derivatives described in the section [1. Composition for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency in plants].

The application of the phosphate absorption enhancer and the application of phosphorus may be performed simultaneously or at different times. In other words, phosphorus fertilization may be performed first, followed by the application of the phosphate absorption enhancer, or the application of the phosphate absorption enhancer may be performed first, followed by the application of the phosphorus fertilizer. Alternatively, the applications may be performed simultaneously for a certain period and separately for another certain period. When the fertilization is performed simultaneously, the phosphorus compound or its derivative may be contained in a single composition of the present invention, or separate compositions may be applied simultaneously.

In this case, the application timing and application form of the phosphorus compound or its derivative can be the same as those described above for the application timing and application form of the phosphate absorption enhancer.

In the method of the present invention, the total amount of phosphorus compound or its derivative required during plant cultivation can be reduced from the conventional total phosphorus application amount without application of a phosphate absorption enhancer (for example, the total amount of phosphorus compound or its derivative calculated by the conventional application amount calculation method determined from the phosphate absorption coefficient and available phosphate amount of the soil in which the plant is cultivated). In one embodiment, the total phosphorus application amount when a plant is cultivated using the phosphate absorption enhancer of the present invention can be 95% or less (per phosphorus weight) of the conventional total phosphorus application amount determined from the phosphate absorption coefficient and available phosphate amount of the soil. In one example, it can be 50% or less of the conventional total phosphorus application amount determined from the phosphate absorption coefficient and available phosphate amount of the soil. In yet another embodiment, the total phosphorus application amount in the method of the present invention can be preferably 30 to 95% of the conventional total phosphorus application amount, more preferably 30 to 90% of the conventional total phosphorus application amount, even more preferably 30 to 75% of the conventional total phosphorus application amount, and most preferably 30 to 50% of the conventional total phosphorus application amount. In this way, by applying the phosphate absorption enhancer of the present invention, the amount of phosphorus applied can be reduced even when applying phosphorus fertilizer, thereby reducing the costs of plant cultivation.

(plant)
As used herein, the term "plant" refers to a whole plant, a plant organ (e.g., leaves, petals, stems, roots, seeds, etc.), a plant tissue (e.g., epidermis, phloem, parenchyma, xylem, vascular bundles, palisade tissue, spongy tissue, etc.), or a plant cultured cell, or various forms of plant cells (e.g., suspension cultured cells), protoplasts, leaf slices, callus, etc.

The plants to which the present invention is applicable are not particularly limited, and can be applied to all kinds of plants, such as various monocotyledonous plants, dicotyledonous plants, and trees. For example, monocotyledonous plants include plants of the Lemnaceae family, which includes plants of the genus Lemna (duckweed) and Lemna (leakweed, leucanthemum); plants of the Orchidaceae family, which include plants of the genus Cattleya, Cymbidium, Dendrobium, Phalaenopsis, Vanda, Paphiopedilum, and Oncidium; plants of the Typhaceae family, Amaranthaceae, Hemerocallidaceae, Brassicae, and Ophiopogonaceae; Examples include plants of the family Polyporaceae, family Perilla, family Gramineae (such as sweet corn and other corn), family Gypsophila, family Palm, family Araceae, family Lycopersicon, family Daylily, family Malvaceae, family Juncaceae, family Santalum, family Liliaceae, family Amaryllidaceae, family Mycorrhizae, family Iris, family Lilies, family Zingiberaceae, family Cannabis, and family Polyporaceae.

In addition, examples of dicotyledonous plants include plants of the family Camphoraceae, including plants of the genus Ipomoea (morning glory), plants of the genus Convolvulus (convolvulus, cauliflower, sea morning glory), plants of the genus Ipomoea (bundleweed, sweet potato), and plants of the genus Cupressaceae (cushion vine, mamedaoshi); plants of the genus Dianthus (carnation, etc.), plants of the genus Chickweed, plants of the genus Alpine clover, plants of the genus Mimosa, plants of the genus Trifolium, plants of the genus Trifolium, plants of the genus Trifolium, plants of the genus Trifolium, and plants of the genus Trifolium. plants of the family Caryophyllales, including plants of the genus Clover, plants of the genus Clover, plants of the genus Silene, plants of the genus Clover, plants of the genus Psammophila ... Cassia, Raggedy, Santalum, Mistle, Horsetail, Ambrosia, Bacillus, Bacillus, Zoysia, Amaranthaceae, Powderwort, Myrtle, Burdock, Vitis, Liliaceae, Magnolias, Bucconaceae, Wigwam, Nectariniaceae, Bacillus, Bacillus subhirtella ... Plants of the Wisteria family, Plantago major family, Camphor family, Papaveraceae family, Atractylodes family, Brassica family (Arabidopsis, cabbage, radish, wasabi, varied mustard, broccoli, etc.), Bryaceae family, Podocarpus family, Scutellaria family, Lamium family, Vitis family, Planaceae family, Rosaceae family, Legume family, Scutellaria family, Galium family, Liliaceae family, Acanthaceae family, Rutaceae, Bitternaceae, Meliaceae, Bacilliaceae, Entrailiae, Brassicae, Boxwood, Scutellaria, Poaceae, Anacardiaceae, Molybdenaceae, Cornus, Atractylodes, Acanthaceae, Maples, Eucalyptus, Scutellaria, Bacillus, Acanthaceae, Acanthaceae, Maples, Eucalyptus, Scutellaria, Acanthaceae ... Plants, Malvaceae, Malvaceae, Cryptomeriae, Theaceae, Bacillarioceae, Lycopersicon esculentum, Thamnophilaea, Violets, Atractylodes, Cornaceae, Passiflora, Cactaceae, Amaranthaceae, Lamiaceae, Pomegranates, Lamiaceae, Cucurbitaceae, Rhododendrons, Elaeaceae, Rubiaceae, Ant-and-Shrimp, Scutellaria, Plants of the family Ginger, Araliaceae, Umbelliferae, Cornaceae, Plum, Albizia, Atractylodes, Rhododendron, Asteraceae, Primula, Scutellaria, Ostrich, Persimmon, Scutellaria, Oleaceae, Bryaceae, Gentianaceae, Aegonia, Asteraceae, Malvaceae, Gentianaceae, Aegoniaceae, Asteraceae, Scutellaria, Violets, Bitter Melonaceae, Lamiaceae, Solanaceae Examples of plants that can be used in the present invention include plants from the family Sesame (such as tomatoes), the family Celastrus, the family Picinale, the family Pedunculaceae, the family Cynaceae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Brassicae, the family Asteraceae (garland chrysanthemum, lettuce, burdock, butterbur, etc.). The plants that are the subject of the present invention may be not only the wild-type plants listed above, but also mutants, transformants, genetically modified plants, and genome-edited plants.

As shown in the examples below, the part of the plant in which phosphorus absorption efficiency and/or phosphorus utilization efficiency is improved is not particularly limited, and may be the harvested product or other parts. The term "harvested product" refers to the part of the plant that serves as food, such as, but not limited to, the fruit in the case of a plant whose fruit is eaten, the seed in the case of a plant whose seed is eaten, the stem in the case of a plant whose stem is eaten, the root in the case of a plant whose root is eaten, the flower in the case of a plant whose flower is eaten, and the leaf in the case of a plant whose leaf is eaten.

3. How to Grow Plants in Phosphorus-Deficient Soils
The present invention also provides a method for growing a plant in phosphorus-deficient soil, comprising cultivating the plant in the phosphorus-deficient soil in the presence of a phosphate absorption enhancer, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.

As described above, the method of the present invention can significantly increase the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants, allowing plants to grow well even in phosphorus-deficient soil. Whether soil is phosphorus deficient or not is determined based on the cultivated plants and cultivation conditions, and is therefore relative, but a person skilled in the art can evaluate it using a method for measuring the amount of phosphorus (or phosphorus) in soil, a method for calculating the phosphorus absorption coefficient, etc.

The method may further include a step of applying a phosphorus compound or a derivative thereof to the plant. The above description of [2. Method for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency in plants] can be applied to the step of applying a phosphate absorption enhancer and the step of applying phosphorus to the plant.

[4. Method for reducing the amount of phosphorus fertilizer applied]
The present invention also provides a method for reducing the amount of phosphorus fertilizer applied to a plant, comprising the steps of cultivating the plant in the presence of a phosphate absorption enhancer and applying the phosphorus fertilizer to the plant, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.

As described above, in the method of the present invention, the total amount of phosphorus fertilizer applied can be reduced compared to the conventional total amount of phosphorus fertilizer applied without the application of a phosphate absorption enhancer (e.g., the total amount of phosphorus fertilizer calculated by the conventional fertilizer amount calculation method determined from the phosphate absorption coefficient and the amount of available phosphate of the soil in which the plant is grown). Here, the phosphorus fertilizer is a fertilizer containing the above-mentioned phosphorus compound or a derivative thereof.

In one embodiment, the total phosphorus application amount when a plant is cultivated using the phosphate absorption enhancer of the present invention can be 95% or less (per phosphorus weight) of the conventional total phosphorus fertilizer application amount determined from the soil phosphate absorption coefficient and the amount of available phosphorus. In one example, the application amount can be 50% or less of the conventional total phosphorus fertilizer application amount determined from the soil phosphate absorption coefficient and the amount of available phosphorus. In yet another embodiment, the total phosphorus fertilizer application amount in the method of the present invention can be preferably 30 to 95% of the conventional total phosphorus fertilizer application amount, more preferably 30 to 90% of the conventional total phosphorus fertilizer application amount, even more preferably 30 to 75% of the conventional total phosphorus fertilizer application amount, and most preferably 30 to 50% of the conventional total phosphorus fertilizer application amount. In this way, by applying the phosphate absorption enhancer of the present invention, the amount of phosphorus fertilizer can be reduced even when phosphorus fertilizer is applied, and the cost of plant cultivation can be reduced.

In addition, in this method, the step of applying the phosphate absorption enhancer to the plant and the step of applying the phosphorus fertilizer to the plant may be performed in either order, or may be performed simultaneously or at different times. In other words, the phosphorus fertilizer may be applied first, followed by the application of the phosphate absorption enhancer, or the phosphorus fertilizer may be applied after the application of the phosphate absorption enhancer. In addition, the steps may be applied simultaneously for a certain period and separately for another certain period. Furthermore, these steps may be repeated. When applying fertilizer simultaneously, the phosphate absorption enhancer and the phosphorus fertilizer (phosphorus compound or its derivative) may be used in a single composition, or separate compositions may be applied simultaneously. For these steps, the description in the above [2. Method for improving phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants] may be applied.

5. Method for producing plants with improved phosphorus absorption efficiency and/or phosphorus utilization efficiency
The present invention further provides a method for producing a plant with improved phosphorus absorption efficiency and/or phosphorus utilization efficiency, comprising the steps of cultivating a plant in the presence of a phosphate absorption enhancer, measuring the phosphorus absorption efficiency and/or phosphorus utilization efficiency in the plant, and selecting, from the plants cultivated with the application of the phosphate absorption enhancer, a plant having improved phosphorus absorption efficiency and/or phosphorus utilization efficiency compared to plants cultivated in the absence of the phosphate absorption enhancer, wherein the phosphate absorption enhancer is glutathione or a derivative thereof.

Since the phosphate absorption enhancer can be absorbed by a plant by contacting it with the plant, the above step can be a step of contacting the phosphate absorption enhancer with the target plant or a step of having the phosphate absorption enhancer absorbed by the target plant. The procedure for absorbing the phosphate absorption enhancer into the plant is not particularly limited, and for example, the plant may be cultivated in a medium (including soil and soil conditioner) containing the phosphate absorption enhancer of the present invention so that the plant absorbs the phosphate absorption enhancer through its roots, or the phosphate absorption enhancer of the present invention may be given as a granule or liquid fertilizer, sprayed, or applied while the plant is being cultivated, so that the plant absorbs the phosphate absorption enhancer. The phosphate absorption enhancer of the present invention may also be adsorbed onto an adsorbent such as an ion exchange resin, and the adsorbent may be buried in soil or otherwise disposed in a medium before cultivating the plant. In other words, the method of the present invention further includes a step of cultivating a plant in the presence of the phosphate absorption enhancer. The specific steps of the steps in the method of the present invention may be in accordance with the above-mentioned form of use of the phosphate absorption enhancer of the present invention.

The concentration of the phosphate absorption enhancer applied may be high or low within a range that can increase the phosphorus absorption efficiency and/or phosphorus use efficiency of the plant, and the desired effect can be achieved by appropriately setting the interval, timing, duration, etc. at which the enhancer is applied. When the total amount of the phosphate absorption enhancer applied throughout the cultivation period is within a specific range, the phosphorus absorption efficiency and/or phosphorus use efficiency of the plant can be increased. The interval, timing, duration, etc. at which the phosphate absorption enhancer is applied The total amount of the phosphate absorption enhancer applied to the plant throughout the cultivation period can be determined by applying the above-mentioned [2. Method for improving phosphorus absorption efficiency and/or phosphorus use efficiency of the plant].

In the plant to which the method of the present invention is applied, phosphorus absorption efficiency and/or phosphorus utilization efficiency are improved. The plant to which the method of the present invention is applied may be a plant to which at least one of phosphorus content, biomass amount, and harvest index is improved. In order to confirm the improvement of phosphorus content in the plant, the method of the present invention includes a step of measuring phosphorus absorption efficiency and/or phosphorus utilization efficiency. The step of measuring phosphorus absorption efficiency and/or phosphorus utilization efficiency may be at least one of a step of measuring phosphorus content, a step of measuring biomass amount, and a step of measuring harvest index. The method of the present invention may further include a step of measuring phosphorus content in the target harvest product of the plant to which the phosphate absorption enhancer is applied. The method of measuring phosphorus content in the plant may be a conventionally known procedure, or may be a procedure described in the examples described below.

The method of the present invention may further include a step of controlling the light conditions at the time of harvesting the plant to which the present invention is applied in order to control the effect of the present invention (i.e., the effect of increasing the phosphorus absorption efficiency and/or phosphorus utilization efficiency of the plant). The control of the light conditions may be a change from light conditions to dark conditions, or from dark conditions to light conditions, or a change in the amount of light under light conditions, and may be performed before harvesting the crop. The start time and control period are not particularly limited as long as the harvest is performed 8 hours or more after the start of the control and before the end of the control. In addition, the start of the control may be before or after the start of application of a phosphate absorption enhancer to the plant, and is preferably performed after the start of application of the phosphate absorption enhancer.

The method of the present invention may further include a step of controlling the temperature conditions during the cultivation period of the plant to which the present invention is applied in order to control the effect of the present invention (i.e., the effect of increasing the phosphorus absorption efficiency and/or phosphorus utilization efficiency of the plant). As shown in the examples described later, even if the plant is grown at a temperature outside the optimum temperature range for plant growth, the phosphorus absorption efficiency and/or phosphorus utilization efficiency in the plant can be improved by applying a phosphate absorption enhancer and controlling the temperature conditions. The control of the temperature conditions may be a change from a high temperature condition to a low temperature condition or a change from a low temperature condition to a high temperature condition, and the start time and control period are not particularly limited as long as the control is started after sowing (preferably germination) and harvesting is performed by the end of the control. The control may be started before or after the start of application of the phosphate absorption enhancer to the plant, and is preferably carried out after the start of application of the phosphate absorption enhancer.

In addition, in order to confirm that the phosphorus absorption efficiency and/or phosphorus utilization efficiency are improved in the plant produced by the production method of the present invention, the plant production method of the present invention further includes a step of selecting a plant having improved phosphorus absorption efficiency and/or phosphorus utilization efficiency compared to a plant cultivated in the absence of a phosphate absorption enhancer. By having the above-mentioned configuration, the desired plant can be successfully selected.

As described above, the method of the present invention improves the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants, and enhances phosphorus absorption by plants. As a result, it is possible to produce plants with significantly improved phosphorus content, biomass volume, and harvest index. In addition, since the plant efficiently absorbs the phosphorus required for growth into the plant body under minimum phosphorus fertilization conditions, the amount of phosphorus fertilization can be reduced. Furthermore, even in a poor environment for plants, such as soil with a low phosphorus concentration or soil or conditions with poor phosphorus content that would conventionally be unsuitable for plant cultivation, the phosphorus absorption by plants is enhanced, and the plants can take in sufficient phosphorus for growth and grow. As a result, it is possible to reduce phosphorus fertilization and efficiently grow plants while reducing the burden on the environment and costs.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. The technical scope of the present invention also includes embodiments obtained by appropriately combining the technical means disclosed in different embodiments.

The following examples are provided to further explain the embodiments of the present invention.

Example 1: Effect of oxidized glutathione fertilization on Arabidopsis thaliana growth in soils with different phosphate contents
(Experimental Method)
A plant growth experiment was carried out.
The plants were cultivated under a photoperiod of 16 hours light/8 hours dark with a light intensity of 100 μE/m ² at a temperature of 22°C.
The culture medium used was vermiculite (Asahi Kogyo) for the bottom layer, Kureha horticultural soil (Kureha) for the middle layer, and vermiculite (Asahi Kogyo) for the top layer, with the volume ratio of bottom:middle:top layer being 2:1:1 (80 mL:40 mL:40 mL).

Arabidopsis seeds were sown in pots containing soil soaked in water and allowed to absorb water from the soil. The only phosphorus fertilizer used in this experiment was phosphorus from Kureha horticultural soil, and this phosphorus condition was designated as P1 (124 mg (phosphate)/100 g (soil)).
Next, the _plants were cultivated in the same manner, except that 100 mM _NaH2PO4 / _Na2HPO4 was applied to the soil from _a dish by bottom irrigation instead of water when allowing the seeds to absorb water, doubling the amount of phosphate fertilizer, and the phosphorus conditions were designated as P2 (248 mg (phosphate)/100 g (soil)).

(Phosphate concentration)
The phosphoric acid concentration conditions used in this experiment are based on the following calculations.
<Phosphorus concentration condition (P1)>
Nutrient content per pot (40 mL) of Kureha horticultural soil: N (nitrogen) 12 mg, P (phosphorus) 30 mg, K (potassium) 18 mg
Amount of P per dish: P30mg x 4 pots = 120mg
120 (mg)/31 = 3.87 mmol
<P2 phosphorus concentration condition (twice the concentration of P1)>
At the time of water absorption, 38.7 mL of 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ was applied per dish as a base fertilizer by bottom irrigation to double the amount of phosphorus.
3.87 mmol of 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ : 3.87 mmol/(100 mmol/L) = 38.7 mL

Next, the plants were given either water alone (control) or a 1 mM oxidized glutathione (GSSG) solution. Specifically, the plants were placed in pots measuring approximately 65 mm (W) x 65 mm (D) x 50 mm (H), with three plants per pot, and four pots were placed on one dish. 25 mL of solution per pot (100 mL per four pots) was added to the dish once a week at 1, 2, 3, 4, and 5 weeks after sowing to provide glutathione to the roots.

The total weight (dry weight), seed amount, and harvest index of the plants obtained from Arabidopsis thaliana (3 plants per pot) grown under the above conditions and no longer growing after 10 weeks from sowing were measured, and the average values for the 16 pots of each treatment were calculated.

Both total and seed weights were measured as dry weights, and the harvest index was calculated as the ratio of seed weight to total plant weight.
The results are shown in Figure 1. Figure 1 shows the results of investigating the effect of fertilization of oxidized glutathione on the growth of Arabidopsis thaliana in soils with different phosphorus contents. Figure 1A shows the total body weight (mg) of Arabidopsis thaliana cultivated under each of the above conditions, Figure 1B shows the seed weight (mg) of Arabidopsis thaliana cultivated under each of the above conditions, and Figure 1C shows the harvest index (n=16 for each) of Arabidopsis thaliana cultivated under each of the above conditions. Figure 1D and E show the seed weight ratio of Arabidopsis thaliana cultivated under each of the above conditions, where the seed weight ratio was calculated based on the GSSG untreated (none) under P1 phosphorus condition in D and the seed weight ratio was calculated based on the GSSG untreated (none) under P2 phosphorus condition in E.

As shown in Figure 1, when treated with 1 mM GSSG, increases in total weight, seed weight, and harvest index were observed in both phosphorus conditions P1 and P2 compared to untreated GSSG (none).

Compared to P1 without glutathione treatment (none), P1 with glutathione treatment (GSSG) increased seed weight by about 21%, and P2 with glutathione treatment increased seed weight by about 26% compared to P2 without glutathione treatment (Fig. 1B). Similarly, compared to P1 without glutathione treatment (none), P1 with glutathione treatment (GSSG) increased harvest index by about 2.4%, and P2 with glutathione treatment increased harvest index by about 2.5% compared to P2 without glutathione treatment (Fig. 1C).

When the amount of phosphorus applied was increased (P2 condition), seed weight increased by about 16% compared to the reduced phosphate condition (P1) without glutathione treatment, even in the absence of glutathione treatment (P2 without glutathione treatment). However, when the amount of phosphorus applied was increased and glutathione was applied (P2 with glutathione treatment), seed weight increased by about 46% compared to the P1 without glutathione treatment (Fig. 1B and D).

Furthermore, when the seed weight of P2 without glutathione treatment was taken as 100%, the seed weight of P1 without glutathione treatment was 86.0% (Fig. 1E). In contrast, the seed weight of P1 with glutathione treatment was 104.1%, and the seed weight of P2 with glutathione treatment was 125.6% (Fig. 1E). In general, when the amount of phosphate applied is reduced from a specified amount (under a reduced phosphate environment), the seed weight decreases compared to the case of a specified amount. However, when glutathione treatment was performed, the seed weight increased even under reduced phosphate conditions (i.e., under P1 conditions) compared to the specified amount (under P2 conditions) (Fig. 1B and E).

Example 2: Effect of oxidized glutathione fertilization on phosphorus content and phosphorus compound content in Arabidopsis thaliana leaf blades
Next, the amount of phosphorus compounds in the leaf blade per dry weight of Arabidopsis thaliana grown under the above-mentioned P1 conditions was examined.

The cultivation method was the same as in Example 1. However, in this experiment, the plants were given only water (Control), 1 mM oxidized glutathione (GSSG) solution, 2 mM reduced glutathione (GSH) solution, or 3 mM ammonium nitrate (NH ₄ NO ₃ ). The concentrations of the three were set so that the amount of nitrogen (N) was the same. Ammonium nitrate was a nitrogen fertilizer and was used as a control fertilizer that did not contain sulfur (S).

The phosphoric acid content was measured by the molybdenum coloring method.
The phosphorus compound content was measured using a CE-TOFMS (capillary electrophoresis-time-of-flight mass spectrometer: Agilent CE-TOFMS system (Agilent Technologies)) in cation and anion modes. The detected peaks were collated with a database based on m/Z and migration time to search for, identify, and quantify phosphorus compounds. For both measurements, plants 4 weeks after sowing were used, and leaf blades were used as samples.

The specimens used in CE-TOFMS were prepared as follows. First, 500 μL of a methanol solution containing a leaf sample and 50 μM of an internal standard was placed in a crushing tube, frozen with liquid nitrogen, and crushed using a tabletop crusher. 500 μL of chloroform and 200 μL of Milli-Q water were added to the sample, stirred, and centrifuged (2300×g, 4° C., 5 minutes). After centrifugation, the aqueous phase was transferred to one 400 μL ultrafiltration tube (MILLIPORE, Ultrafree MC UFC3 LCC Centrifugal Filter Unit 5 kDa).
This was centrifuged (9100×g, 4° C., 120 minutes) and the aqueous phase was subjected to ultrafiltration.
The filtrate was dried and dissolved in 50 μL of Milli-Q water for measurement.

Figures 2 and 3 show the results of investigating the effects of fertilization with oxidized glutathione or reduced glutathione, respectively, on the phosphate content and phosphorus compound content in Arabidopsis leaf blades. Figure 2 shows the phosphate content in the leaf blades per mg of fresh weight of Arabidopsis. Figure 3 shows the phosphorus compound content in the leaf blades per dry weight of Arabidopsis.

As shown in Figure 2, the phosphate content per fresh weight in Arabidopsis leaf blades not treated with glutathione (None) was 9.76 nmol/mg. On the other hand, with 1 mM GSSG treatment, the content was 11.13 nmol/mg (14% increase) (the figures in parentheses indicate the percentage increase when the amount of phosphorus compounds in Arabidopsis leaf blades not treated with glutathione is taken as 100%).

As shown in Fig. 3, the phosphorus compound content per dry weight in Arabidopsis leaf blades not treated with glutathione (Control) was 306.5 nmol/g. On the other hand, the phosphorus compound content was 342.6 nmol/g (12% increase) in the 1 mM GSSG treatment and 349.5 nmol/g (14% increase) in the 2 mM GSH treatment (the figures in parentheses indicate the percentage increase when the phosphorus compound content in the Arabidopsis leaf blades not treated with glutathione is taken _as 100%). On the other hand, the phosphorus compound content in the 3 mM _NH4NO3 (equivalent N content in GSSG and GSH molecules) was 252.7 nmol (18% decrease).

Example 3: Effect of oxidized glutathione fertilization on the growth of chrysanthemum (garland chrysanthemum) in soil fertilized with various concentrations of phosphate (1)
The effect of fertilizing oxidized glutathione on the growth of Chrysanthemum natans (Chrysanthemum natans), a vegetable of the Asteraceae family, in soil fertilized with various concentrations of phosphoric acid was examined. After sowing, Chrysanthemum natans that had germinated uniformly were selected and cultivated in an incubator (light period: 14 hours at 20°C/dark period: 10 hours at 15°C, light intensity: approximately 250 μE/ ^m2 /s). The medium used was soil layered with 2 parts vermiculite (Asahi Kogyo) in the bottom layer, 1 part Kureha nursery soil (Kureha) in the middle layer, and 1 part vermiculite (Asahi Kogyo) in the top layer.

Chrysanthemum seeds were sown in pots filled with soil soaked in water and allowed to absorb water. The only phosphorus fertilizer used in this case was from Kureha horticultural soil, and this phosphorus condition was designated P1.

Next, instead of water for soaking the soil, 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ was irrigated from the bottom of the dish to increase the amount of phosphate fertilization to twice or four times that of P1, and these phosphorus conditions were designated as P2 and P4. That is, P1 was 30 mg of P containing Kureha culture soil, P2 was phosphate buffer equivalent to P1 + 30 mg, and P4 was phosphate buffer equivalent to P1 + 90 mg, and the total phosphorus amount was adjusted so that P2 was twice that of P1 and P4 was four times that of P1 based on P1. P1, P2 and P4 (516 mg (phosphate) / 100 g (soil)) were sown and cultivated in the same manner except for the different phosphorus conditions.

(Phosphate concentration)
The phosphoric acid concentration conditions used in this experiment are based on the following calculations.
<P1 (P30 mg) phosphorus concentration conditions>
Nutrient content per pot (40 mL) of Kureha horticultural soil: N 12 mg, P 30 mg, K 18 mg
Amount of P per dish: P30mg x 3 pots = 90mg
90 (mg)/31=2.90 mmol
<P2 (P1 + P30 mg) phosphorus concentration condition (twice the concentration of P1)>
At the time of water absorption, 29.0 mL of 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ was applied per dish as a base fertilizer by bottom irrigation to double the amount of phosphorus.
Calculation formula: 2.90 mmol of 100 _{mM NaH2PO4} / _Na2HPO4 : 2.90 mmol/( ₁₀₀ mmol/L) = 29.0 mL
<P4 (P1 + P90 mg) phosphorus concentration condition (4 times the concentration of P1)>
At the time of water absorption, _29.0 mL x 3 = 87.0 mL of 100 mM _NaH2PO4 / _Na2HPO4 was given per dish as base fertilizer by bottom irrigation to increase the phosphorus content _by four times.

Next, the plants were given either water alone (None) or a 2 mM oxidized glutathione (GSSG) solution. Specifically, the plants were placed in pots measuring approximately 65 mm (W) x 65 mm (D) x 50 mm (H), with one plant per pot. 25 mL of the solution per pot was given to the roots once a week at the 1st, 2nd, 3rd, 4th, and 5th weeks after sowing.

The fresh weight of garland chrysanthemums (one individual per pot) grown under the above conditions in soil with and without GSSG treatment and at each phosphorus concentration was measured 7 weeks after sowing.

Figure 4 shows the results of an investigation into the effect of fertilizing oxidized glutathione on the growth of Garland chrysanthemum in soil fertilized with various concentrations of phosphorus. As shown in Figure 4, the greater the amount of phosphorus applied, the better the plant growth.

FIG. 5 shows the results of investigating the effect of fertilization of oxidized glutathione on the live weight of Garland chrysanthemum in soil fertilized with various concentrations of phosphate.
When grown only in Kureha soil (P1), the fresh weight of the non-glutathione treated (None) was 2.8 g, while that of the glutathione treated (GSSG) was 3.8 g, showing an increase of 36%. When the amount of phosphate was doubled (P2), the fresh weight of the non-treated was 3.0 g, while that of the glutathione treated was 5.3 g, showing an increase of 77%. When the amount of phosphate was quadrupled (P4), the fresh weight of the non-treated was 2.8 g, while that of the glutathione treated was 5.1 g, showing an increase of 82%.

Example 4: Effect of oxidized glutathione fertilization on the growth of chrysanthemum (garland chrysanthemum) in soil fertilized with various concentrations of phosphate (2)
Using the conditions of P1 in Example 3 above as a standard, the effects of conditions of phosphorus concentrations lower than P1 on the growth of garland chrysanthemum in soil fertilized with phosphorus at various concentrations were examined.

The cultivation conditions were the same as in Example 3. After sowing, seeds with uniform germination were selected and cultivated in an incubator (light period: 14 hours at 20° C./dark period: 10 hours at 15° C., light intensity: approximately 250 μE/m ² /s).

Instead of the medium in Example 3, soil was used in which vermiculite (Asahi Kogyo) was used for the bottom layer, Kureha horticultural soil (Kureha) for the middle layer, and vermiculite (Asahi Kogyo) for the top layer, with the volume ratio of bottom layer:middle layer:top layer being 7:1:8 (70 mL:10 mL:80 mL).

Next, the soil was soaked in 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ or water by bottom irrigation with 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ or water from the dish, and the amount of phosphate fertilization was set to 1/2 times the amount of P1 and P1 (62 mg (phosphate) / 100 g (soil)) or 1/4 times the amount (31 mg (phosphate) / 100 g (soil)). Furthermore, by adding a solution of 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ and 16.9 mg / ml KNO ₃ , nitrogen (N) and potassium (K) nutrient contents were supplemented so that they were equivalent under any of the conditions of P1, P _{1 / 2} , and P _{1 / 4} .

That is, P1 was phosphate buffer equivalent to P7.5 mg + P22.5 mg of the Kureha culture soil, totaling 30 mg of P, P1 _/2 was phosphate buffer equivalent to P7.5 mg + P7.5 mg of the Kureha culture soil, totaling 15 mg of P, and P1 _/4 was phosphorus condition containing only 7.5 mg of Kureha culture soil, P7.5 mg of P, and the total phosphorus amount was adjusted so that P1 _/2 was 1/2 times that of P1 and P1 _/4 was 1/4 times that of P1, based on P1.

(Phosphate concentration and Nitrogen (N) and Potassium (K) concentration)
The phosphoric acid concentration conditions used in this experiment are based on the following calculations.
Nutrient content per pot (10 mL) of Kureha horticultural soil: N 3 mg, P 7.5 mg, K 4.5 mg
As a supplement per dish, in order to make up for the difference with the Kureha culture soil (P1) in Example 3 (30 ml of Kureha culture soil), 10 ml of 16.9 mg/ml KNO3 + 21.8 ml of ₁₀₀ mM _NaH2PO4 / _Na2HPO4 were applied as base fertilizer to 30 _ml of _Kureha culture soil at the time of water absorption by bottom irrigation, and the amount of phosphorus was designated P1 (P30 mg).

<P1 (P30 mg) phosphorus concentration conditions>
Formula:
Amount of P per dish: (P 30 mg - P content of Kureha soil 7.5 mg) x 3 pots = 67.5 mg
67.5 (mg)/31=2.18 mmol
2.18 mmol of 100 _{mM NaH2PO4} / _Na2HPO4 : 2.18 mmol/( ₁₀₀ mmol/L) = 21.8 mL
Amount of N per dish: _KNO3 16.9 mg/ml x 10 mL = 169 mg (N: 23.4 mg, K: 65.3 mg)
N content per dish: Kureha soil N content 3mg x 3 + 23.4mg = 32.4mg
Amount of potassium per dish: K-content of Kureha soil 4.5mg x 3 + 65.3mg = 78.8mg

<P1 _/2 (P15 mg) phosphorus concentration condition (1/2 amount of P1)>
As a supplement per dish, in order to make up for the difference with the Kureha culture soil (P1) in Example 3 (30 ml of Kureha culture soil), ₁₀ ml of 16.9 mg/ml KNO3 + 7.3 ml of 100 mM _NaH2PO4 / _Na2HPO4 were applied as base fertilizer to 30 _ml of _Kureha culture soil at the time of water absorption by bottom irrigation to set the phosphorus content to P1 _/2 (P15 mg).
Formula:
Amount of P per dish: (P 15 mg - P content of Kureha soil 7.5 mg) x 3 pots = 22.5 mg
2.5 (mg)/31=0.73 mmol
0.73 mmol of 100 mM NaH ₂ PO ₄ /Na ₂ HPO ₄ : 0.73 mmol/(100 mmol/L) 7.3 ml

<P _1/4 phosphorus concentration condition (1/4 amount of P1)>
As a supplement per dish, in order to make up for the difference with the Kureha culture soil (P1) in Example 3 (30 ml of Kureha culture soil), 10 ml of 16.9 mg/ml KNO3 + water was applied as a base fertilizer _to 30 ml of Kureha culture soil at the time of water absorption by bottom irrigation to set the phosphorus content to P1 _/4 (P7.5 mg).

Figure 6 shows the results of an investigation into the effect of oxidized glutathione fertilization on the growth of Garland chrysanthemum in soil fertilized with various concentrations of phosphate under conditions of phosphate concentrations lower than P1.

Next, for the Garland chrysanthemum plants grown under the above-mentioned P1, P1 _/2 and P1 _/4 conditions, plants were sampled 7 weeks after sowing, and the phosphorus content in the leaf blade per fresh weight was examined. The phosphorus content was quantified by the molybdenum coloring method, as in the case of Arabidopsis thaliana in Example 2.

Table 1 below shows the fresh weight of garland chrysanthemums grown under each P condition in this example.

FIG. 7 is a diagram showing the phosphorus content (Pi content) in the leaf blade per mg of Garland Chrysanthemum fresh weight. None, 0.2, and 1 on the horizontal axis of FIG. 7 indicate no treatment, 0.2 mM treatment, and 1 mM treatment of GSSG, respectively. As shown in FIG. 7, the phosphorus content in the leaf blade was higher when oxidized glutathione was applied in P1. On the other hand, in P1 _/2 , no difference was observed in the phosphorus content in the leaf blade between the case with and without oxidized glutathione application. Furthermore, in P1 _/4 , the phosphorus content was lower with oxidized glutathione application than without it.

Example 5: Effect of oxidized glutathione fertilization on phosphorus utilization efficiency of garland chrysanthemum
Next, using the results of Example 4, the phosphate content per Garland chrysanthemum plant and the phosphorus utilization efficiency were calculated.

Formula:
Phosphate content per plant (μmol Pi/plant) = Phosphate content per mg fresh weight (nmol Pi/mg FW) × Fresh weight (mg FW/plant)
Phosphorus utilization efficiency (mg FW/nmol Pi) = fresh weight (mg FW/plant)/phosphate content per plant (nmol Pi/plant)

FIG. 8 is a diagram showing the phosphorus content and phosphorus utilization efficiency per Garland chrysanthemum individual. None, 0.2, and 1 on the horizontal axis of FIG. 8 indicate no treatment, 0.2 mM treatment, and 1 mM treatment of GSSG, respectively. As shown in FIG. 8, the phosphorus content per individual was higher when oxidized glutathione was applied in P1. On the other hand, the phosphorus content per individual was lower in P1 _/4 with oxidized glutathione application than without it. As shown in the results of FIG. 7 and FIG. 8 above, the phosphorus utilization efficiency was improved in P1 _/4 with oxidized glutathione application than without it.

Example 6: Effect of foliar application of oxidized glutathione on lettuce growth
(Experimental Method)
Lettuce (variety: Souther) was used in the growth experiment.
The seedlings were sown in a 200-hole tray (14 ml of soil per plant) and grown in an incubator for 2 weeks under a 16-hour light/8-hour dark photoperiod with a light intensity of about 100 μE/m2 at ^a temperature of 22°C. After that, the seedlings were transplanted into 9 cm pots (402 ml of soil per plant) and grown in a glass greenhouse for 2 weeks. The soil used for both the seedling and pot cultivation was cell soil (manufactured by Takii Seeds). The fertilizer components of the cell soil were N (nitrogen) 320 mg/L, P (phosphate) 210 mg/L, and K (potassium) 300 mg/L. There was one plant per cell and pot, and 9 plants were replicated in the untreated area and the glutathione-treated area.

Oxidized glutathione was applied to the leaves twice in total, once in the third week of seedling growth and once in the fourth week of seedling growth (at the time of planting), by spraying 0.25 mmol/L on the leaves at 0.09 ml/plant/time (100 ml/m ² /time) using a spray bottle.
The phosphorus concentration conditions were 1.3 mg/cell during seedling cultivation and 84.3 mg/pot during pot cultivation (95 mg (phosphate)/100 g (soil)).

The above-ground weight (dry weight) and total phosphorus content of lettuce grown under the above conditions were investigated. The results are shown in Table 2. Above-ground weight increased significantly by 9% in the GSSG treatment compared to the untreated treatment, and total phosphorus increased by 20%. This shows that spraying glutathione also improves phosphorus absorption efficiency.

The method of the present invention can improve the phosphorus absorption efficiency and/or phosphorus utilization efficiency of plants, and therefore the present invention has industrial applicability in a wide range of fields, including agriculture and the food industry.

Claims (12)

A composition for improving phosphorus uptake efficiency and/or phosphorus utilization efficiency of a plant in phosphorus-deficient soil or under phosphorus-deficient conditions , comprising a phosphate absorption enhancer,
A composition, wherein the phosphate absorption enhancer is glutathione or a derivative thereof. The composition of claim 1 , wherein the glutathione or a derivative thereof is selected from the group consisting of oxidized glutathione, reduced glutathione, homoglutathione, carboxypropyl glutathione, dicarboxyethyl glutathione, and esters thereof. 3. The composition of claim 1 or 2 , further comprising or used in combination with a phosphorus compound or a derivative thereof. 4. The composition of claim 3 , wherein the phosphorus compound or a derivative thereof is selected from the group consisting of superphosphate, triple superphosphate, fused phosphorus, burnt phosphorus, ammonium phosphate, phosphorous acid and organic phosphorus. A method for improving phosphorus uptake efficiency and/or phosphorus utilization efficiency in a plant, comprising:
The method includes cultivating a plant in the presence of a phosphate absorption enhancer,
The method, wherein the phosphate absorption enhancer is glutathione or a derivative thereof. 1. A method for reducing the amount of phosphorus fertilizer applied to a plant, comprising:
Cultivating a plant in the presence of a phosphate absorption enhancer;
and applying a phosphorus fertilizer to the plant,
The method, wherein the phosphate absorption enhancer is glutathione or a derivative thereof. 1. A method for growing plants in phosphorus deficient soil, comprising:
Cultivating a plant in the phosphorus-deficient soil in the presence of a phosphate absorption enhancer,
The method, wherein the phosphate absorption enhancer is glutathione or a derivative thereof. 8. The method of claim 7 , further comprising the step of applying a phosphorus compound or a derivative thereof to the plant. A method for producing a plant with improved phosphorus uptake efficiency and/or phosphorus utilization efficiency, comprising the steps of:
Cultivating a plant in the presence of a phosphate absorption enhancer;
and measuring phosphorus uptake efficiency and/or phosphorus utilization efficiency in the plant,
The method, wherein the phosphate absorption enhancer is glutathione or a derivative thereof. The method described in claim 9, further comprising a step of selecting, from among the plants cultivated with the application of the phosphate absorption enhancer, plants having improved phosphorus absorption efficiency and/or phosphorus utilization efficiency compared to plants cultivated in the absence of the phosphate absorption enhancer . 10. The method of claim 5, 6 or 9 , wherein the step of cultivating the plant comprises cultivating the plant in phosphorus-deficient soil or in phosphorus-deficient conditions. The method according to any one of claims 5 to 11 , wherein the glutathione or a derivative thereof is selected from the group consisting of oxidized glutathione, reduced glutathione, homoglutathione, carboxypropyl glutathione, dicarboxyethyl glutathione, and esters thereof.