PLANT GROWTH REGULATOR AND METHOD FOR PROMOTING PLANT GROWTH

In order to provide a plant growth regulator with an excellent plant growth promoting effect, the plant growth regulator of the present invention includes a compound represented by Formula (I) or its tautomer, or an agrochemically acceptable salt thereof.   where R1 and R2 each independently represent a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms, and R3 to R5 each independently represent an alkyl group having from 1 to 4 carbon atoms.

TECHNICAL FIELD

The present invention relates to a plant growth regulator and use thereof.

BACKGROUND ART

There has been a demand for an agent having a high plant growth promoting effect on a wide range of plants. Examples of such agents include oxidized glutathione (Patent Document 1).

CITATION LIST

Patent Document

SUMMARY OF INVENTION

Technical Problem

However, existing agents are not sufficient in their growth promoting effect, and there is still a demand for a plant growth regulator exhibiting an excellent growth promoting effect. Therefore, the present invention has been made in view of the above problem, and intended to provide a plant growth regulator excellent in the plant growth promoting effect.

Solution to Problem

As a result of diligent studies by the present inventors, surprisingly, it was found that an excellent plant growth promoting effect can be obtained by using a specific antioxidant, which has been conventionally used for foods, medical products, and cosmetics, as a plant growth regulator, and thus the present invention has been completed. That is, in order to solve the problems described above, the plant growth regulator according to the present invention includes a compound represented by Formula (I) or its tautomer, or an agrochemically acceptable salt thereof as an active ingredient:

where in Formula (I), R1and R2each independently represent a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms, and R3to R5each independently represent an alkyl group having from 1 to 4 carbon atoms.

The method for promoting plant growth according to the present invention includes treating a plant with the compound represented by Formula (I) or its tautomer, or an agrochemically acceptable salt thereof.

Advantageous Effects of Invention

According to the present invention, a plant growth regulator having an excellent plant growth promoting effect can be provided.

DESCRIPTION OF EMBODIMENTS

An embodiment of the plant growth regulator according to the present invention will be described.

Plant Growth Regulator

Active Ingredients

The plant growth regulator according to the present embodiment includes a compound represented by Formula (I) (hereinafter simply referred to as “compound (I)”) or its tautomer, or an agrochemically acceptable salt thereof as an active ingredient:

where in Formula (I), R1and R2each independently represent a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms. R3to R5each independently represent an alkyl group having from 1 to 4 carbon atoms.

The alkyl group may be linear or branched, that is, may be a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group or a tert-butyl group.

At least one of R1and R2is preferably a hydrogen atom, and more preferably both are hydrogen atoms. When R1and R2are alkyl groups, they are preferably methyl groups, ethyl groups or propyl groups, more preferably methyl groups or ethyl groups, and even more preferably methyl groups.

R3to R5are each preferably independently a methyl group, an ethyl group or a propyl group, more preferably a methyl group or an ethyl group, and even more preferably a methyl group. At least one of R3to R5is preferably a methyl group, more preferably at least two are methyl groups, and even more preferably all are methyl groups.

“Its tautomer” refers to a tautomer of compound (I). Compound (I) has a tautomer when at least one of R1and R2is a hydrogen atom. More specifically, when R2is a hydrogen atom in Formula (I), the compound represented by Formula (II) below (hereinafter simply referred to as “compound (II)”) can exist as a tautomer. In addition, when R1is a hydrogen atom in Formula (I), the compound represented by Formula (III) below (hereinafter simply referred to as “compound (III)”) can exist as a tautomer. Compounds (II) and (III) are hereinafter collectively referred to simply as “tautomers”.

where in Formulas (II) and (III), R1to R5are the same as R1to R5in Formula (I).

The preferred compound as compound (I) or its tautomer is specifically ergothioneine, and L-(+)-ergothioneine is more preferred.

As these compounds, commercially available compounds may be used, or those synthesized by a technique well known to those skilled in the art, for example, a technique described in JP 2013-506706 T or JP 2006-160748 A may be used. Ergothioneine is known to be produced by bacteria and fungi. Examples of the production method using such a microorganism include the methods described in JP 2012-105618 A, JP 2014-223051 A, WO 2016/104437, WO 2016/121285, WO 2015/168112, and WO 2017/150304. As ergothioneine, a culture containing ergothioneine obtained from these microorganisms may be used as it is, or ergothioneine may be concentrated or purified before use.

“Agrochemically acceptable” usually means those are safe, non-toxic, and not undesired biologically or otherwise, but those acceptable for pesticides, especially for pesticides that promote plant growth.

The “agrochemically acceptable salt” of compound (I) or its tautomer is a salt that is agrochemically acceptable as defined above, and means those can provide the action and effect of compound (I) or its tautomer. Examples of such salts include hydrates, solvates, acid addition salts, salts formed when the acidic proton present in compound (I) or its tautomer are replaced with metal ions, and salts formed when the acidic proton coordinates with an organic base or an inorganic base.

Examples of the metal ion capable of substituting the acidic proton present in compound (I) or its tautomer include an alkali metal ion, an alkaline earth metal ion, and an aluminum ion.

Examples of the organic base capable of coordinating with the acidic proton present in compound (I) or its tautomer include diethanolamine, ethanolamine, N-methylglucamine, triethanolamine, and tromethamine. Examples of the inorganic base include aluminum hydroxide, calcium hydroxide, potassium hydroxide, sodium carbonate, and sodium hydroxide.

The plant growth regulator according to the present embodiment includes compound I or its tautomer, or an agrochemically acceptable salt thereof as an active ingredient, thereby exhibiting an excellent growth promoting effect in a plant treated with the regulator. In the present specification, “excellent in growth promoting effect” means that at least one of the plant growth indices is superior to known compounds. Examples of the “plant growth index” include plant height, number of tillers, number of flowers, number of fruits, and seed yield.

The plant growth regulator according to the present embodiment preferably includes a compound represented by Formula (I) or an agrochemically acceptable salt thereof as an active ingredient. The plant growth regulator according to the present embodiment may include a plurality of compounds among compound (I) or its tautomer, or an agrochemically acceptable salt thereof as an active ingredient.

Normally, in a solution, compound (I) and compound (II) or (III) can exist in equilibrium. The ratio of compound (I) to compound (II) or (III) can vary depending on the solvent, temperature, pH, or the like.

Applicable Plant

The plant growth regulator in the present embodiment generally exhibits a growth promoting effect on all plants, and examples of applicable plants include the following: Poaceae such as rice, wheat, barley, rye, oats, triticale, corn, sorghum, sugar cane, turf, bentgrass, bermudagrass, fescue, and ryegrass; legumes such as soybean, peanut, kidney bean, peas, adzuki beans, and alfalfa; Convolvulaceae such as sweet potatoes; solanaceae such as capsicum, pepper, tomato, eggplant, potato, and tobacco; Polygonaceae such as buckwheat; Asteraceae such as sunflower; Araliaceae such as ginseng; Brassicaceae such as rapeseed, Chinese cabbage, turnip, cabbage, and Japanese radish; Chenopodiaceae such as sugar beet; Malvaceae such as cotton; Rubiaceae such as coffee tree; Sterculiaceae such as cacao; Camellia such as tea; Cucurbitaceae such as watermelon, melon, cucumber, and pumpkin; Liliaceae such as onion, leeks, and garlic; Rosaceae such as strawberries, apples, almonds, apricots, Japanese apricots, cherry, plums, peaches, and pears; Apiaceae such as carrots; Araceae such as taro; Larvae such as mango; Pineapples such as pineapples; Carica such as papayas; Ebenaceae such as persimmons; Ericaceae such as blueberries, walnuts such as pecans; Musaceae such as bananas; Oleaceae such as olives; Palmae such as coconut, and date; Rutaceae such as mandarin orange, orange, grapefruit, and lemon; Vitaceae such as grapes; flowers and ornamental plants, trees other than fruit trees; and other ornamental plants.

Other examples include wild plants, cultivars, plants and cultivars bred by conventional hybridizing or plasmogamy, and genetically recombinant plants and cultivars obtained by gene manipulation. Examples of genetically recombined plants and cultivars include herbicide-tolerant crops, pest-resistant crops in which an insecticidal protein-producing gene has been recombined, pathogen-resistant crops in which a pathogen resistance derivative-producing gene has been recombined, taste-improved crops, yield-improved crops, and preservation-improved crops. Examples of genetically recombined cultivar that has been approved in each country include those stored in the database of the International Service for the Acquisition of Agri-biotech Applications (ISAAA). Specific examples include those containing trade names such as Roundup Ready, Liberty Link, IMI, SCS, Clearfield, Enlist, B.t., BXN, Poast Compatible, AgriSure, Genuity, Optimum, Powercore, DroughtGard, YieldGard, Herculex, WideStrike, Twinlink, VipCot, GlyTol, Newleaf, KnockOut, BiteGard, BtXtra, StarLink, Nucotn, NatureGard, Protecta, SmartStax, Power Core, InVigor, and Bollgard.

Formulation

The plant growth regulator is generally prepared by mixing compound (I) or its tautomer, which is an active ingredient, or a mixture thereof, with a solid carrier or a liquid carrier (diluent), a surfactant, and other formulation aid and the like, and formulating the mixture into various forms such as a dustable powder, a wettable powder, a granule, and an emulsifiable concentrate for use.

Examples of the solid carrier, liquid carrier, and surfactant used as formulation aids are as follows. First, examples of the solid carrier include minerals such as clay, talc, diatomaceous earth, zeolite, montmorillonite, bentonite, acid clay, activated clay, attapulgite, calcite, vermiculite, perlite, pumice, and silica sand; synthetic organic substances such as urea; salts such as calcium carbonate, sodium carbonate, sodium sulphate, slaked lime, and baking soda; synthetic inorganic substances such as amorphous silica such as white carbon and titanium dioxide; plant carriers such as wood flour, corn stalk (cob), walnut shell (nut shell), fruit core, chaff, sawdust, bran, soy flour, powdered cellulose, starch, dextrin, and sugars; and various polymeric carriers such as crosslinked lignin, cation gel, gelatin gelated by heat or a polyvalent metal salt, water-soluble polymer gel such as agar, chlorinated polyethylene, chlorinated polypropylene, polyvinyl acetate, polyvinyl chloride, ethylene-vinyl acetate copolymer, and urea-aldehyde resin.

Examples of the other formulation aid include inorganic salts used as pH adjusters such as sodium and potassium; fluorine-based and silicon-based defoamers; water-soluble salts such as common salt; water-soluble polymers used as thickeners such as xanthan gum, guar gum, carboxymethyl cellulose, polyvinylpyrrolidone, carboxyvinyl polymer, acrylic polymer, polyvinyl alcohol, starch derivatives and polysaccharides; alginic acid and salts thereof; metal stearates, sodium tripolyphosphate, sodium hexametaphosphate used as disintegrating dispersants; preservatives; colorants; antioxidants; UV absorbers; chemical damage reducers; and deterioration inhibitors.

Some formulations are used as they are and some are diluted with a diluent such as water to a predetermined concentration before use. The concentration of compound (I) when diluted before use is preferably in the range from 0.0001 to 1 wt. %. The same applies to the tautomers of compound (I).

These formulations are prepared so that compound (I) is contained as an active ingredient in an amount of 0.1 to 90 wt. %, and more preferably 0.2 to 50 wt. %. The amount of compound (I) used is from 0.005 to 50 kg, and more preferably from 0.03 to 30 kg per 1 ha of agricultural and horticultural land such as fields, rice fields, orchards, and greenhouses. The same applies to the tautomers of compound (I). Since the concentration and quantity used differ depending on the form of the agent, time of use, usage method, usage location, target crops and the like, they may be increased or decreased without being limited to the above range.

Other Active Ingredients

The plant growth regulator in the present embodiment may be used in combination with other known active ingredients to enhance the performance as a plant growth regulator. Examples of the other known active ingredients include active ingredients contained in known plant growth regulators, fungicides, insecticides, acaricides, nematicides, and herbicides.

Examples of the phenylamide compounds include benalaxyl, benalaxyl M or chiralaxyl, metalaxyl, metalaxyl M or mefenoxam, and oxadixyl.

Examples of the dicarboximide compounds include procymidone, iprodione, and vinclozolin.

Examples of the anilinopyrimidine compounds include cyprodinil, mepanipyrim, and pyrimethanil.

Examples of the antibiotics include kasugamycin, polyoxin, streptomycin, validamycin, and oxytetracycline.

Examples of the carbamate compounds include benthiavalicarb (benthiavalicarb-isopropyl), diethofencarb, iprovalicarb, propamocarb, and tolprocarb.

Examples of the quinoline compound include oxolinic acid, pyroquilon, quinoxyfen, and tebufloquin.

Examples of effective components suitable for insecticidal use include organophosphorus compounds, carbamate compounds, pyrethroid compounds, nereistoxin compounds, neonicotinoid compounds, benzoylurea compounds, other insect growth control compounds, organic chlorine compounds, and compounds derived from natural products.

Examples of the nereistoxin compounds include cartap, bensultap, thiocyclam, monosultap, and bisultap.

Examples of other insect growth control compounds include buprofezin, chromafenozide, cyromazine, halofenozide, methoxyfenozide, tebufenozide, and pyriproxyfen.

Examples of the organic chlorine compounds include aldrin, dieldrin, endosulfan, methoxychlor, lindane, and DDT.

Examples of the amino acid compounds include bialaphos and salts thereof, glufosinate and salts thereof, glufosinate P and salts thereof, and glyphosate and salts thereof.

Examples of the bipyridinium compounds include diquat and paraquat.

Examples of the allyloxyphenoxypropionic acid compounds include clodinafop and clodinafop propargyl, cyhalofop butyl, diclofop and diclofop-methyl and diclofop-p-methyl, fenoprop and fenoprop-ethyl and fenoprop-p-ethyl, fluazifop and fluazifop-butyl and fluazifop-p-butyl, haloxyfop and haloxyfop methyl and haloxyfop-p-methyl, metamifop, propaquizafop and quizalofop and quizalofop-ethyl and quizalofop-p-ethyl, and quizalofop-P-tefuryl.

Examples of the phenoxyacetic acid compound include 2,4-D and salt thereof, 2,4-DB and salt thereof, clomeprop, dichlorprop, MCPA and salt thereof, MCPB and salt thereof, and mecoprop (MCPP) and salt thereof, and mecoprop P and salt thereof.

Method for Promoting Plant Growth

The plant growth regulator in the present embodiment may be used, for example, in cultivated lands such as fields, paddy fields, lawns, and orchards or non-cultivated lands. The plant growth regulators in the present embodiment can be used by all methods of fertilization, such as spraying on stems and leaves, mixing into water supply, spraying on soil, injecting into subsoil using an injector, seed treatment including treatment of bulbs and tubers, and direct fertilization to plants. Therefore, the method for promoting plant growth in the present embodiment includes a procedure for fertilizing using the above-mentioned plant growth regulator.

In the case of application by mixing with feed water, for example, water is fed to the crop, or the water surface of a paddy field may be treated with granules or the like. In one example, the concentration of the active ingredient in the feed water is from 0.5 to 500 mg/L, and preferably from 1 to 300 mg/L. The amount of the active ingredient used when administered to paddy water is, for example, from 0.5 to 5000 g, and preferably from 3 to 3000 g per 10 a of paddy field.

In the case of application by foliar application or application to soil, a planting hole or the vicinity thereof may be treated with granules or the like in the transplantation of seedling or the like, or seeds or the earth around a plant may be treated with granules, a wettable powder, or the like. In addition, it may be preferable to mix with soil after spraying on the soil. The amount of the active ingredient used for foliar application or application to the soil surface is, for example, from 0.5 to 5000 mg, and preferably from 3 to 3000 mg per 1 m2of agricultural and horticultural land.

In seed treatment, the agent is applied to the seeds by mixing and stirring wettable powders and dustable powders with the seeds or by dipping the seeds in diluted wettable powders. The seed treatment also includes seed coating treatments. The amount of active ingredients used in the case of seed treatment is, for example, from 0.005 to 10,000 g, and preferably from 0.05 to 1,000 g per 100 kg of the seeds. Seeds treated with agricultural or horticultural chemicals can be used in the same way as common seeds.

Additionally, since the concentration and quantity used differ depending on the form of the agent, time of use, usage method, usage location, target crops and the like, they may be increased or decreased within the above ranges. As described above, compound (I) and its tautomer exhibit an excellent growth promoting effect on a wide range of plants.

Use of Plant Growth Regulator

The plant growth regulators in this embodiment exhibit an excellent growth promoting effect in treated plants, as described above. Therefore, the plant growth regulator in this embodiment can be used, for example, as biostimulants and fertilizers. The plant growth regulator in this embodiment may also be mixed with soil conditioners and pesticides for use.

The term “fertilizer” is primarily intended for anything that acts on plants or soil for the purpose of supplying nutrients to plants or causing chemical changes in the soil. The term “biostimulant” is primarily intended for anything that acts on plant physiology through a different pathway than nutrients for the purpose of improving crop vitality, yield, and quality.

Summary

As described above, the plant growth regulator according to the present invention includes a compound represented by Formula (I) or its tautomer, or an agrochemically acceptable salt thereof as an active ingredient:

where in Formula (I), R1and R2each independently represent a hydrogen atom or an alkyl group having from 1 to 4 carbon atoms, and R3to R5each independently represent an alkyl group having from 1 to 4 carbon atoms.

The plant growth regulator according to the present embodiment preferably includes a compound represented by Formula (I) or an agrochemically acceptable salt thereof as an active ingredient.

In the plant growth regulator according to the present invention, in Formula (I), at least one of R1and R2is preferably a hydrogen atom.

Additionally, in the plant growth regulator according to the present invention, in Formula (I), it is preferred that R1and R2are hydrogen atoms, and R3to R5are methyl groups.

In the plant growth regulator according to the present invention, the compound represented by Formula (I) is preferably L-(+)-ergothioneine.

The method for promoting plant growth according to the present invention includes treating a plant with the compound represented by Formula (I) or its tautomer, or an agrochemically acceptable salt thereof.

Embodiments of the present invention will be described in further detail hereinafter using examples. The present invention is not limited to the examples below, and it goes without saying that various aspects are possible with regard to the details thereof. Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible within the scope indicated in the claims. Embodiments obtained by appropriately combining the technical means disclosed by the embodiments are also included in the technical scope of the present invention. In addition, all of the documents described in the present specification are herein incorporated by reference.

EXAMPLES

Sample

Arabidopsis thaliana(Col-O) was sown in plastic pots having a width of 65 mm, a depth of 65 mm, and a height of 70 mm, three individuals per pot. Plastic deep dishes each having a diameter of 160 mm and a height of 28 mm were prepared, and three pots were respectively placed therein. As soil, 100 mL of vermiculite, 50 mL of granular soil (JA Granular Kumiai Synthetic Soil No. 3), and 50 mL of vermiculite were placed in each pot in this order.

Control Conditions

In a thermostatic chamber set at room temperature of 25° C., the light period was 16 hours and the dark period was 8 hours. The light conditions were set using a fluorescent lamp (PLANT FLEC, 40 W LED fluorescent lamp for plant growth, electric bulb color, available from Nippon Medical and Chemical Instruments Co., Ltd.) so that the light intensity was 5000 lx in the central part under the fluorescent lamp irradiation. Water supply was done from the bottom, and the water level was set at about 5 mm. Ergothioneine treatment was started 4 weeks after seeding. More specifically, on the 21st, 23rd, 25th, and 27th days after seeding, 50 mL of a 1 mM L-(+)-ergothioneine (available from Cayman Chemical) aqueous solution was added instead of water supply.

Verification

On the 37th day after seeding, the plant height (cm) and the number of flowers and fruits per Arabidopsis thalianawere measured. The results are shown in Table 1.

Comparative Example 1

The same operation as in Example 1 was carried out except that L-(+)-ergothioneine in the aqueous solution was replaced with oxidized glutathione (available from Wako Pure Chemical Industries, Ltd.).

Comparative Example 2

The same operation as in Example 1 was carried out except that the L-(+)-ergothioneine aqueous solution was replaced with distilled water.

Sample

One individualArabidopsis thaliana(Col-O) was sown in a plastic pot having a diameter of 60 mm and a height of 55 mm. Plastic deep dishes each having a diameter of 160 mm and a height of 28 mm were prepared, and six pots were respectively placed therein. As soil, 45 mL of vermiculite, 22.5 mL of granular soil (JA Granular Kumiai Synthetic Soil No. 3), and 22.5 mL of vermiculite were placed in each pot in this order.

Control Conditions

The procedure was the same as in Example 1, except that the room temperature was set to 22° C.

Verification

On the 85th day after seeding, seeds were harvested, and the seed yield (mg/plant) was measured. The results are shown in Table 2.

The same operation as in Example 2 was carried out except that the concentration of L-(+)-ergothioneine aqueous solution was set to 0.1 mM.

The same operation as in Example 2 was carried out except that the concentration of L-(+)-ergothioneine aqueous solution was set to 0.01 mM.

Comparative Example 3

The same operation as in Example 2 was carried out except that L-(+)-ergothioneine in the aqueous solution was replaced with oxidized glutathione (available from Wako Pure Chemical Industries, Ltd.).

Comparative Example 4

The same operation as in Example 2 was carried out except that L-(+)-ergothioneine in the aqueous solution was replaced with L-glutamic acid (available from Wako Pure Chemical Industries, Ltd.).

Comparative Example 5

The same operation as in Example 2 was carried out except that L-(+)-ergothioneine in the aqueous solution was replaced with L-proline (available from Wako Pure Chemical Industries, Ltd.).

Comparative Example 6

The same operation as in Example 2 was carried out except that the L-(+)-ergothioneine aqueous solution was replaced with distilled water.

Sample

The same operation as in Example 2 was carried out.

Control Conditions

The same operation as in Example 1 was carried out except that the room temperature was set at 22° C. and L-(+)-ergothioneine was added 2 weeks after seeding, more specifically on the 8th, 10th, 12th, and 14th days.

Verification

On the 82nd day after seeding, seeds were harvested, and the seed yield (mg/plant) was measured. The results are shown in Table 3.

The same operation as in Example 5 was carried out except that L-(+)-ergothioneine was added 4 weeks after seeding, more specifically on the 22nd, 24th, 26th, and 28th days.

Comparative Example 7

The same operation as in Example 5 was carried out except that oxidized glutathione was used in place of L-(+)-ergothioneine in the aqueous solution and added 4 weeks after seeding, more specifically on the 22nd, 24th, 26th, and 28th days.

Comparative Example 8

The same operation as in Example 5 was carried out except that the L-(+)-ergothioneine aqueous solution was replaced with distilled water.

Analysis

The ratio of “grass height” and “flowers and fruits” for Example 1, Comparative Example 1, and Comparative Example 2 to the results of Comparative Example 2 are shown in Table 1 as “Ratio”, respectively. The “seed yield” for Examples 2 to 4 and Comparative Examples 3 to 6 are shown as “Ratio” in Table 2, where the value for Comparative Example 6 is set to 1. The “seed yield” for Examples 5 and 6 and Comparative Examples 7 and 8 are shown as “Ratio” in Table 3, where the value for Comparative Example 8 is set to 1.