Plant cultivation method, and use of compound having quinone skeleton for reducing decline in quality of plant harvest or increasing plant harvests

Abstract

The present invention addresses the problem of providing a plant cultivation method or the like for reducing a decline in the quality of a plant harvest or increasing plant harvests. This plant cultivation method is characterized in that a compound other than 2-methyl-1,4-naphthoquinone among compounds having a quinone skeleton represented by general formula (I) is sprayed during the seedling stage of plants. (In formula, R1 represents a hydrogen atom, a hydroxyl group, a halogen atom, a methyl group, an alkenyl group, an alkoxy group (excluding a methoxy group) or the like, R2 represents a hydrogen atom or a halogen atom, R3 represents a hydrogen atom, a hydroxyl group, or a nitro group, R4 represents a hydrogen atom, a hydroxyl group, or a nitro group, and R5 represents a hydrogen atom or a nitro group.)

Description

Method for cultivating plants and use of compounds having a quinone skeleton for reducing quality loss in plant harvest or for increasing plant harvest

[0001] The present invention relates to a method for cultivating plants by spraying a compound having a quinone skeleton on the plants during the seedling stage, and to the use of said compound for reducing deterioration in the quality of the plant harvest or for increasing the plant harvest.

[0002] It is generally known that plants exhibit stress defense responses, such as the expression of stress response genes, when exposed to various environmental stresses. However, due to the recent rapid environmental deterioration, such as heat stress caused by global warming, poor plant growth, particularly reduced productivity of agricultural crops, has become an international problem. In recent years, even in Japan, there have been many cases of agricultural crops being damaged by heat and dryness during the extremely hot summer months. For example, the occurrence of immature grains, such as white grain rice, has become a problem for grasses due to the heat and dry winds caused by the intense heat.

[0003] Various countermeasures against such plant stress have been investigated. For example, a method of controlling the growth environment by blocking sunlight using agricultural materials such as greenhouse cultivation is known. However, this method requires extensive and large-scale construction, which is problematic in that it is very expensive. In addition, a method of producing heat-tolerant plants through crossbreeding has attracted attention as a fundamental method for improving the heat tolerance of plants themselves. However, crossbreeding is time-consuming and labor-intensive, and there is a problem in that it is not possible to efficiently produce the desired plants that can adapt to rapid environmental degradation.

[0004] Therefore, currently, methods for inducing stress tolerance in plants using stress tolerance inducers are being explored. Research into stress tolerance inducers has focused on natural ingredients, as disclosed in, for example, Patent Documents 1 and 2. Patent Document 1 discloses an agricultural and horticultural high temperature stress tolerance enhancer containing a licorice extract as an active ingredient. By administering the agricultural and horticultural high temperature stress tolerance enhancer to tomatoes, the number of saleable fruits is improved. Patent Document 2 discloses a pharmaceutical composition for imparting environmental stress tolerance, which contains a yeast cell wall enzyme hydrolysate. This pharmaceutical composition has the effect of restoring or promoting the growth of vegetables.

[0005] Japanese Patent Application Laid-Open No. 11-199419 Japanese Patent Application Laid-Open No. 2007-45709

[0006] However, as disclosed in Patent Documents 1 and 2, there has been a problem in that the effect of using natural ingredients as active ingredients to restore or promote the growth of plants such as vegetables and grains is still insufficient.

[0007] The present invention is based on the discovery that spraying a compound having a specific quinone skeleton during the seedling raising stage exerts an excellent effect of reducing deterioration in the quality of plant harvests or increasing plant harvests.

[0008] The following describes various aspects of the method for solving the above problems. Aspect 1 is a method for cultivating plants, which comprises spraying a formulation containing, as an active ingredient, a compound having a quinone skeleton represented by the following general formula (I), excluding 2-methyl-1,4-naphthoquinone, during the seedling stage of the plants:

[0009]

[0010] (In the formula, R 1 is a hydrogen atom, a hydroxyl group, a halogen atom, a methyl group, an alkenyl group, an alkoxy group (excluding a methoxy group), or —CHR 6 -CH2CH=C(CH3) 2 represents a group, R 2 represents a hydrogen atom or a halogen atom, R 3 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 4 represents a hydrogen atom, a hydroxyl group, or a nitro group; R5 represents a hydrogen atom or a nitro group, R 6 represents a hydrogen atom or —OCO—R 7 represents a group, R 7 is an alkyl group, a hydroxyalkyl group having one or more hydroxyl groups, an alkenyl group, or -R 8 -OCO-R 9 group, and further R 8 is -C n H 2n - represents a hydrocarbon (n=2 or more) consisting of R 9 represents an alkyl group.) Aspect 2 is a method for cultivating plants, comprising spraying, during the seedling raising stage, a formulation containing, as an active ingredient, at least one compound selected from 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-amino-3-chloro-1,4-naphthoquinone, shikonins, and alkanins.

[0011] Aspect 3 is the plant cultivation method according to Aspect 2, wherein the shikonins are at least one selected from shikonin, deoxyshikonin, acetylshikonin, isobutyrylshikonin, α-methyl-n-butylshikonin, isovalerylshikonin, β-hydroxyisovalerylshikonin, β,β-dimethylacrylshikonin, and β-acetoxyisovalerylshikonin, and the alkanines are at least one selected from alkanine, deoxyalkanine, acetylalkanine, isobutyrylalkanine, α-methyl-n-butylalkanine, isovalerylalkanine, β-hydroxyisovalerylalkanine, β,β-dimethylacrylshikonin, and β-acetoxyisovalerylalkanine.

[0012] Aspect 4 is the method for cultivating a plant according to any one of Aspects 1 to 3, wherein the method is used to reduce a decrease in quality of a harvested product of the plant or to increase the harvested product of the plant. Aspect 5 is the method for cultivating a plant according to any one of Aspects 1 to 4, wherein the plant is a plant of the order Poaceae or the order Cucurbitaceae.

[0013] Aspect 6 is a use of a compound having a quinone skeleton represented by the following general formula (I), excluding 2-methyl-1,4-naphthoquinone, for reducing deterioration in quality of harvested plants or for increasing harvested plants, wherein the compound is sprayed on plants during the seedling stage.

[0014]

[0015] (In the formula, R 1 is a hydrogen atom, a hydroxyl group, a halogen atom, a methyl group, an alkenyl group, an alkoxy group (excluding a methoxy group), or —CHR 6 -CH2CH=C(CH3) 2 represents a group, R 2 represents a hydrogen atom or a halogen atom, R 3 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 4 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 5 represents a hydrogen atom or a nitro group, R 6 represents a hydrogen atom or —OCO—R 7 represents a group, R 7 is an alkyl group, a hydroxyalkyl group having one or more hydroxyl groups, an alkenyl group, or -R 8 -OCO-R 9 group, and further R 8 is -C n H 2n - represents a hydrocarbon (n=2 or more) consisting of R 9 represents an alkyl group. Aspect 7 is a use of at least one compound selected from 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-amino-3-chloro-1,4-naphthoquinone, shikonins, and alkanines for reducing deterioration in plant harvest quality or increasing plant harvest yield, wherein the compound is sprayed during the seedling stage of the plant.

[0016] Aspect 8 is the use according to aspect 6 or 7, wherein the plant is a plant of the order Poaceae or Cucurbitaceae.

[0017] According to the present invention, an excellent effect of reducing the deterioration of the harvested product of a plant or an excellent effect of increasing the harvested product of a plant can be exhibited.

[0018] (First embodiment) Hereinafter, a first embodiment of the plant cultivation method of the present invention (hereinafter referred to as "first cultivation method") will be described.

[0019] The first cultivation method of the present embodiment is a method in which a formulation containing, as an active ingredient, a compound having a quinone skeleton represented by the following general formula (I), excluding 2-methyl-1,4-naphthoquinone, is sprayed on plants during the seedling raising stage.

[0020]

[0021] (In the formula, R 1 is a hydrogen atom, a hydroxyl group, a halogen atom, a methyl group, an alkenyl group, an alkoxy group (excluding a methoxy group), or —CHR 6 -CH2CH=C(CH3) 2 represents a group, R 2 represents a hydrogen atom or a halogen atom, R 3 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 4 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 5 represents a hydrogen atom or a nitro group, R 6 represents a hydrogen atom or —OCO—R 7 represents a group, R 7 is an alkyl group, a hydroxyalkyl group having one or more hydroxyl groups, an alkenyl group, or -R 8 -OCO-R 9 group, and further R 8 is -C n H 2n - represents a hydrocarbon (n=2 or more) consisting of R 9 represents an alkyl group.) The above active ingredient can exert an excellent effect of reducing the deterioration of the quality of the harvested product of a plant or an excellent effect of increasing the harvested product of a plant.

[0022] The compound represented by general formula (I) is a compound having a naphthoquinone skeleton. Specific examples of the halogen atom constituting the substituent include fluorine, chlorine, iodine, and bromine. The carbon chain constituting the alkyl group, alkenyl group, or alkoxy group may be linear or branched. These active ingredients may be used alone or in combination of two or more.

[0023] Specific examples of the compound represented by general formula (I) include 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-amino-3-chloro-1,4-naphthoquinone, shikonins shown below, and alkanins which are enantiomers of the shikonins.

[0024] Specific examples of shikonins include shikonin, deoxyshikonin, acetylshikonin, isobutyrylshikonin, α-methyl-n-butylshikonin, isovalerylshikonin, β-hydroxyisovalerylshikonin, β,β-dimethylacrylshikonin, etc. Shikonins are natural pigment components present in the roots of Boraginaceae plants in the form of esters such as acetylshikonin, and therefore crude extracts or purified products extracted from such plant materials may also be used.

[0025] Specific examples of alkanines include alkanine, deoxyalkanine, acetylalkanine, isobutyrylalkanine, α-methyl-n-butylalkanine, isovalerylalkanine, β-hydroxyisovalerylalkanine, β,β-dimethylacrylalkanine, etc. Alkanines are natural pigments present in borage, and therefore crude extracts or purified products extracted from such plant materials may also be used.

[0026] Also, R in the formula 1 , R 3 , R 4 a compound having a hydroxyl group in any one of R 1 and R 2 Compounds having a halogen atom in any one of the above, the above-mentioned shikonins, and the above-mentioned alkanins are preferred.

[0027] The plants to which the formulations described above are applied may be either angiosperms or gymnosperms, and specific examples thereof include plants of the Solanales, Umbellidales, Caryophyllales, Asterales, Legumes, Liliales, Rosales, Cucurbitales, Theales, Pinales, Myrtales, Lamiales, Sapindales, Vitales, Poales, Brassicales, Zingiberales, and Scutellariales. More specifically, for example, Solanaceae plants such as eggplant, bell pepper, chili pepper, potato, etc.; Umbelliferae plants such as carrot, celery, Bupleurum, etc.; Chenopodiaceae plants such as beet, spinach, etc.; Asteraceae plants such as garland chrysanthemum, lettuce, burdock, gerbera, chrysanthemum, etc.; Leguminaceae plants such as soybean, pea, licorice, alfalfa, sweet pea, etc.; Liliaceae plants such as leek, onion, garlic, tulip, etc.; Rosaceae plants such as strawberry, rose, apple, peach, pear, etc.; Cucurbitaceae plants such as watermelon, melon, cucumber, etc.; Convolvulaceae plants such as sweet potato, etc.; Theaceae plants such as tea, camellia, etc.; Myrtaceae plants such as eucalyptus, etc.; Oleaceae plants such as olive, etc.; Satsuma mandarin (warm mandarin orange), etc. Examples of suitable plants include citrus plants such as mandarin oranges (Okinawa mandarins), lemons, grapes, and other Vitaceae plants, Lamiaceae plants such as perilla, basil, mint, rosemary, and sage, grasses such as rice, wheat, barley, oats, millet, foxtail millet, barnyard millet, rye, bamboo, corn, lawn grass, ryegrass, sugarcane, and Job's tears, Brassicaceae plants such as Arabidopsis thaliana, radish, komatsuna (Japanese mustard greens), bok choy, broccoli, and cabbage, Musaceae plants such as bananas, Anacardiaceae plants such as mango, Passifloaceae plants such as passionflower, Papaya, evergreen trees such as Pinaceae and Cupressaceae, evergreen perennials such as Asparagaceae and Asparagaceae, bryophytes, and other tropical plants.

[0028] Among these, plants of the order Poaceae and Cucurbitaceae are preferred from the viewpoint of excellent effects of reducing deterioration in plant harvest quality and increasing plant harvest. The above-mentioned formulations are applied by spraying, immersing, etc., to the target plants during the seedling raising stage. The formulations may be in either solid or liquid form, with solid formulations having the advantages of excellent storage stability and liquid formulations having excellent immediate effect and sprayability. Examples of solid formulations include powder, granule, and granular forms. When a solid formulation is applied, it may be directly sprayed, or it may be dissolved in a solvent such as water and diluted to a predetermined concentration, and then applied by spraying, spraying, injection, irrigation, etc. Liquid formulations include not only solutions but also dosage forms such as suspensions and gels. When the above-mentioned formulations are prepared as liquids, they may be directly sprayed, or they may be diluted to a predetermined concentration and applied by spraying, spraying, injection, irrigation, etc. The formulation may be applied to at least one of the plant organs of the plant to which it is applied, such as leaves, stems, trunks, and roots, or may be applied to the base of the plant or the soil. The formulation to be applied to plants of the order Poaceae may be applied not only to the plant or soil, but also indirectly by spraying it into the water in a channel leading to the field where the seedlings are placed.

[0029] The application time is not particularly limited as long as it is during the seedling raising period. The seedling raising period refers to the period from when seeds are disinfected, if necessary, and soaked in water to promote germination, to when they are sown in seedling raising pots or seedling raising boxes, and when they are raised, until when the seedlings are planted in a rice paddy or field. Furthermore, the seedling raising period also includes the stage before germination is promoted, when the seeds are simply soaked in water. The seedling raising period may be any of the soaking period, the germination period, the sowing period, and the germination to hardening period. Of these, the soaking period, the germination period, and the sowing period are preferred from the viewpoint of ease of sowing the formulation. Furthermore, of these, the sowing period is preferred from the viewpoint of saving the effort of wastewater treatment.

[0030] When a liquid formulation is used, the concentration of the quinone compound in the solution can be appropriately set depending on the type of compound, the plant variety, etc., but is preferably 0.001 μM to 1000 mM, more preferably 0.01 μM to 100 mM, and even more preferably 0.1 μM to 10 mM. In particular, when the component is a shikonin or alkanin, the concentration is preferably 0.01 μM to 1000 mM, more preferably 0.1 μM to 100 mM, and even more preferably 1 μM to 10 mM. By specifying this concentration range, it is possible to reduce the burden on the plant body while improving the effect of reducing the decline in plant harvest quality or increasing plant harvest yield.

[0031] When such a formulation is sprayed on, for example, a grass plant, it reduces the deterioration of the quality of the harvested product of the grass plant. For example, in the case of rice, it has the effect of preventing the formation of immature grains, which occur at a high rate due to high temperature damage. Immature grains include, for example, white immature grains, milky white grains, white-core grains, white-basal grains, white-back grains, white-belly grains, dead grains, and cracked grains. The type of rice is not particularly limited, and the rice whose quality is evaluated may be either polished rice or brown rice.

[0032] Spraying such a formulation on the above-mentioned plants increases the plant's harvest. The first cultivation method of this embodiment can provide the following effects: (1) The first cultivation method of this embodiment is a method in which a formulation containing, as an active ingredient, a compound having a quinone skeleton represented by the following general formula (I) described above, excluding 2-methyl-1,4-naphthoquinone, is sprayed on plants during the seedling raising stage. Therefore, spraying such a formulation on target plants during the seedling raising stage can provide an excellent effect of reducing deterioration in the plant's harvest quality or increasing the plant's harvest.

[0033] For example, during the extremely hot summer months, grains such as rice can suffer from environmental stresses such as the heat and dry winds that cause them to produce immature grains, such as cloudy white grains. By suppressing the occurrence of immature grains, it is possible to prevent deterioration in appearance and quality, as well as a drop in selling price.

[0034] (2) The quinone compound represented by the general formula (I) may be chemically synthesized or commercially available. Alternatively, a crude extract extracted from a natural material or a purified component may be used. Therefore, a formulation can be obtained inexpensively, and expensive agricultural materials are not required. The effect of reducing the decline in plant harvest quality or increasing plant harvest can be achieved at low cost.

[0035] (3) Through the above effects, the present invention contributes to the achievement of the 17 goals and 169 targets of the SDGs (Sustainable Development Goals), particularly "2. Zero Hunger" and "13. Take urgent action to combat climate change."

[0036] Second Embodiment A second embodiment of the plant cultivation method of the present invention (hereinafter referred to as the "second cultivation method") will be described below, focusing on the differences from the first embodiment.

[0037] The second cultivation method of this embodiment involves spraying a formulation containing the compound described below as an active ingredient on plants during the seedling raising stage. The active ingredient used in the second cultivation method of this embodiment is at least one compound selected from 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-amino-3-chloro-1,4-naphthoquinone, shikonins, and alkanins. These compounds may be used singly or in combination of two or more.

[0038] Specific examples of shikonins include shikonin, deoxyshikonin, acetylshikonin, isobutyrylshikonin, α-methyl-n-butylshikonin, isovalerylshikonin, β-hydroxyisovalerylshikonin, β,β-dimethylacrylshikonin, β-acetoxyisovalerylshikonin, etc. Since shikonins are natural pigment components present in the roots of Boraginaceae plants in the form of esters such as acetylshikonin, crude extracts or purified products extracted from such plant materials may also be used.

[0039] Specific examples of the alkanines include alkanine, deoxyalkanine, acetylalkanine, isobutyrylalkanine, α-methyl-n-butylalkanine, isovalerylalkanine, β-hydroxyisovalerylalkanine, β,β-dimethylacrylalkanine, β-acetoxyisovalerylalkanine, etc. Alkanines are natural pigments present in borage, and therefore crude extracts or purified products extracted from such plant materials may also be used.

[0040] The plants to which the formulation is applied, the formulation form, and the application method are the same as those in Embodiment 1. By spraying such a formulation on plants during the seedling raising stage, an effect of reducing the deterioration of the quality of the harvested products of excellent plants can be obtained.

[0041] By spraying such a formulation on plants during the seedling raising stage, an effect of increasing a good harvest can be obtained. The second cultivation method according to this embodiment has the following advantages in addition to the effects of the first embodiment.

[0042] (4) A second cultivation method according to this embodiment involves spraying a formulation containing the above-mentioned 1,4-naphthoquinone or the like as an active ingredient onto plants during the seedling raising stage. Therefore, spraying such a formulation onto target plants during the seedling raising stage can provide an excellent effect of reducing deterioration in the quality of the plant harvest or increasing the plant harvest.

[0043] (Third Embodiment) Hereinafter, a third embodiment of the present invention, which embodies the use of a compound having a quinone skeleton for reducing deterioration in the quality of harvested products of plants or for increasing the harvested products of plants, will be described, focusing on the differences from the first embodiment.

[0044] In this embodiment, compounds having a quinone skeleton represented by general formula (I) described in the first embodiment, excluding 2-methyl-1,4-naphthoquinone, are used. These compounds may be used alone or in combination of two or more.

[0045] In addition, compounds containing, as an active ingredient, any compound having a quinone skeleton represented by general formula (I) other than 2-methyl-1,4-naphthoquinone are agents for reducing the deterioration of harvested plant products or agents for increasing harvested plant products.

[0046] The plants to which the agent for reducing quality degradation of harvested products of plants or the agent for increasing harvested products of plants are applied, and the formulation or application method of the formulation are the same as those in the first embodiment. The agent for reducing quality degradation of harvested products of plants is sprayed during the seedling raising stage of the plants to reduce the degradation of the harvested products of the plants.

[0047] The plant yield increasing agent is sprayed during the seedling raising stage of the plant to increase the plant yield. This embodiment has the following advantages in addition to the effects of the first embodiment.

[0048] (5) In this embodiment, a compound having a quinone skeleton represented by general formula (I), excluding 2-methyl-1,4-naphthoquinone, is used to reduce the deterioration of plant harvest quality or increase plant harvest yield, and the compound is sprayed during the seedling stage of plants. Therefore, an excellent effect of reducing the deterioration of plant harvest quality or increasing plant harvest yield can be obtained.

[0049] (Fourth embodiment) Hereinafter, a fourth embodiment of the present invention, which embodies the use of a compound having a quinone skeleton for reducing deterioration in the quality of harvested products of plants or for increasing the harvested products of plants, will be described, focusing on the differences from the second embodiment.

[0050] In this embodiment, at least one compound selected from the group consisting of 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-amino-3-chloro-1,4-naphthoquinone, shikonins, and alkanins is used. These compounds may be used alone or in combination of two or more.

[0051] The plant harvest quality reduction agent or plant harvest increase agent contains these compounds such as 1,4-naphthoquinone as an active ingredient. The plants to which the plant harvest quality reduction agent or plant harvest increase agent is applied, and the formulation or application method of the formulation are the same as those in the second embodiment.

[0052] The plant harvest quality reduction agent is sprayed during the seedling stage to reduce the deterioration of the plant harvest quality. The plant harvest increase agent is sprayed during the seedling stage to increase the plant harvest.

[0053] This embodiment has the following advantages in addition to the effects of the second embodiment. (6) In this embodiment, the above-mentioned compound such as 1,4-naphthoquinone is used to reduce the deterioration of plant harvest quality or increase the plant harvest, and the compound is sprayed during the seedling raising stage of plants. Therefore, an excellent effect of reducing the deterioration of plant harvest quality or increasing the plant harvest can be obtained.

[0054] The above embodiments may be modified as follows: In the above embodiments, the active ingredient may be used in combination with known additives, solvents, etc. to improve solubility, stability, applicability, various efficacies, etc. Known additives include, for example, surfactants, water-soluble polymers, lubricants, antioxidants, preservatives, binders, bulking agents, and pesticide active ingredients.

[0055] In each of the above embodiments, the active ingredient may be applied in combination with a conventional plant growth regulator, plant environmental stress tolerance agent, insecticide, plant antiviral agent, acaricide, fertilizer, or the like.

[0056] The active ingredient of the above embodiment may be configured as an agent for reducing quality deterioration of plant harvest products to be sprayed during the seedling raising period, or as an agent for increasing plant harvest products to be sprayed during the seedling raising period.

[0057] Next, the above-described embodiment will be described in more detail with examples and comparative examples. The present invention is not limited to the configurations described in the examples. (Test Example 1: Test 1 for Reducing Rice Quality Deterioration by Naphthoquinone Compounds) Using paddy rice (variety: Koshihikari) as the plant and a lithospermum root extract containing shikonins as the naphthoquinone compounds, the effect of reducing rice quality deterioration was tested. The lithospermum root extract used was Shikonix Liquid (BG) (manufactured by Ichimaru Falcos Co., Ltd.), which contains purple root extract. Shikonix Liquid (BG) contains acetylshikonin, β-hydroxyisovalerylshikonin, and isobutyrylshikonin as the main components of the shikonins. It also contains α-methyl-n-butylshikonin, β,β-dimethylacrylshikonin, isovalerylshikonin, and shikonin as minor components.

[0058] (1) Overview of paddy rice cultivation The cultivation schedule for the paddy rice (variety: Koshihikari) used in the test is shown in Table 1. The cultivation location was Aichi Prefecture.

[0059]

[0060] (2) Seed soaking treatment (March 27th to March 31st) Seed soaking treatment was carried out from March 27th by soaking 15 bags of rice seeds (15 kg of rice seeds per bag) in 1000 L of water. In Example 1, at around 8:00 on the same day, 1 L of the above-mentioned Syconix Liquid (BG) was added to the 1000 L of water in which the rice seeds were soaked, and the mixture was stirred well for treatment. The bags were removed in the morning of April 1st, and the treatment was completed. In Example 2 and Comparative Example 1, the seed soaking treatment was carried out according to the usual method without using Syconix Liquid (BG).

[0061] (3) Stimulated germination treatment (April 1st) In Example 2, 1 L of the above-mentioned Syconix Liquid (BG) was dissolved in 1000 L of water, and 15 bags of rice seeds were added. The treatment was carried out for about 8 hours in a germination machine (manufactured by Tiger Kawashima, set at 30°C). In Example 1 and Comparative Example 1, germination treatment was carried out according to the usual method without using Syconix Liquid (BG).

[0062] (4) Seeding period, germination period to hardening period (hardening period treatment: April 18th) In each example and comparative example, seeds were sown in seedling raising boxes using a seed sowing machine, and seedling raising was continued according to the usual procedure.

[0063] (5) Transplanting, Harvesting, and Quality Inspection For each example and comparative example, seedlings were transplanted into one paddy field per test plot on April 25th. Harvesting was carried out on August 25th, with 10 seeds per test plot per replicate x 3 replicates. Brown rice was obtained by drying, threshing, hulling, and sieving (mesh opening: 1.85 mm). Quality inspection was carried out using a grain classifier (RGQI 100B, manufactured by Satake Corporation) to measure the proportion of whole grains. The quality inspection results of the brown rice are shown in Table 2 below.

[0064]

[0065] As shown in Table 2, it was confirmed that Examples 1 and 2, in which Syconix Liquid (BG) was sprayed during the soaking or germination period, had a significantly increased rate of size-regulating grains compared to Comparative Example 1, which was an untreated area.

[0066] (Test Example 2: Test 2 on reducing rice quality deterioration by naphthoquinone compounds) Using paddy rice (variety: Hinohikari) as the plant body and Lithospermum Root extract containing shikonins as the naphthoquinone compound, the effect of reducing rice quality deterioration was tested. The Lithospermum Root extract used was commercially available under the trade name Siconix Liquid (BG) (manufactured by Ichimaru Falcos Co., Ltd.).

[0067] (1) Overview of paddy rice cultivation The cultivation schedule for the paddy rice (variety: Hinohikari) used in the test is shown in Table 3. The cultivation location is Fukuoka Prefecture.

[0068]

[0069] (2) Seed soaking stage, germination stage, sowing stage, germination stage to hardening stage Comparative Example 2 was carried out according to the usual procedures in the seed soaking stage, germination stage, sowing stage, and germination stage to hardening stage.

[0070] In Example 3, at the time of sowing, the above-mentioned Syconix Liquid (BG) was diluted with water by about 460 times and sprayed at about 450 mL / box on the rice seeds sown in the seedling boxes. Otherwise, the procedure was carried out according to a conventional method.

[0071] (3) Transplanting, heading, harvesting, and quality inspection In each example and comparative example, seedlings were transplanted into paddy fields on June 26th according to standard procedures. In comparative example 2, at the heading stage, the above-mentioned Syconix Liquid (BG) was diluted with water by about 40 times and sprayed by drone onto the paddy rice in the field at a rate of 8 L / ha.

[0072] The rice was harvested on October 10th, and the brown rice was obtained by drying, threshing, hulling, and sieving. A quality inspection was performed using a grain classifier (Satake Corporation, RGQI 100B) to measure the percentage of whole grains. The results of the brown rice quality inspection are shown in Table 4 below.

[0073]

[0074] As shown in Table 4, it was confirmed that Example 3, in which Syconix Liquid (BG) was sprayed at the sowing stage, had a significantly increased rate of size adjustment compared to Comparative Example 2, in which Syconix Liquid (BG) was sprayed at the heading stage.

[0075] (Test Example 3: Test 3 for reducing rice quality deterioration by naphthoquinone compounds) Using paddy rice (variety: Koshihikari) as the plant body and Lithospermum Root extract containing shikonins as the naphthoquinone compounds, the effect of reducing rice quality deterioration was tested. The Lithospermum Root extract used was commercially available under the trade name Siconix Liquid (BG) (manufactured by Ichimaru Falcos Co., Ltd.).

[0076] (1) Overview of paddy rice cultivation The cultivation schedule for the paddy rice (variety: Koshihikari) used in the test is shown in Table 5. The cultivation location was Ibaraki Prefecture.

[0077]

[0078] (2) Seed soaking stage, germination stage, sowing stage, germination stage to hardening stage Comparative Example 3 was carried out according to the usual procedures in the seed soaking stage, germination stage, sowing stage, and germination stage to hardening stage.

[0079] In Example 4, during the hardening period, the above-mentioned Syconix Liquid (BG) was diluted with water by about 590 times and sprayed at 500 mL per seedling box on May 9. (3) Transplanting, Harvesting, and Quality Inspection In each Example and Comparative Example, seedlings were transplanted into paddy fields on May 10 according to conventional procedures.

[0080] The rice was harvested on September 15th, and the brown rice was obtained by drying, threshing, hulling, and sieving (mesh size: 1.85 mm). A grain discriminator (RGQI 100B, manufactured by Satake Corporation) was used to inspect the quality of the brown rice, and the percentage of whole grains was measured. The results of the inspection of the brown rice quality are shown in Table 6 below.

[0081]

[0082] As shown in Table 6, it was confirmed that Example 4, in which Syconix Liquid (BG) was sprayed during the hardening period, had an increased rate of size-regulating grains compared to the untreated Comparative Example 3. (Test Example 4: Evaluation test of rice using naphthoquinone compounds) Using paddy rice (variety: Koshihikari) as the plant body and a lithospermum root extract containing shikonins as the naphthoquinone compound, rice yield was tested. Syconix Liquid (BG) (manufactured by Ichimaru Falcos Co., Ltd.) was used as the lithospermum root extract.

[0083] (1) Overview of paddy rice cultivation The cultivation schedule for the paddy rice (variety: Koshihikari) used in the test is shown in Table 7. The cultivation location is Ishikawa Prefecture.

[0084]

[0085] (2) Seed soaking stage, germination stage, sowing stage, germination stage to hardening stage Comparative Example 4 was carried out according to the usual procedures in the seed soaking stage, germination stage, sowing stage, and germination stage to hardening stage.

[0086] In Example 5, during the hardening period, the above-mentioned Syconix Liquid (BG) was diluted about 500 times with water and sprayed at 500 mL per seedling box on May 2. (3) Transplanting, Harvesting, and Quality Inspection In each of the Examples and Comparative Examples, seedlings were transplanted into paddy fields on May 3 according to conventional procedures.

[0087] Harvesting took place in early September, followed by drying, threshing, hulling, and sieving (mesh size: 1.85 mm) to obtain brown rice. Yield testing was performed using standard methods, measuring the number of ears, number of grains per ear, thousand-kernel weight, and ripening percentage. The results of the brown rice yield testing are shown in Table 8 below.

[0088]

[0089] As shown in Table 8, Example 5, in which Syconix Liquid (BG) was sprayed during the hardening period, had an increased number of grains per panicle, thousand-grain weight, and ripened rate compared to the untreated Comparative Example 4, confirming that it had a superior yield.

Claims

1. A method for cultivating plants, which comprises spraying a formulation containing as an active ingredient a compound having a quinone skeleton represented by the following general formula (I), excluding 2-methyl-1,4-naphthoquinone, during the seedling stage of the plants: (In the formula, R 1 is a hydrogen atom, a hydroxyl group, a halogen atom, a methyl group, an alkenyl group, an alkoxy group (excluding a methoxy group), or -CHR 6 -CH2CH=C(CH3) 2 R represents a group; 2 represents a hydrogen atom or a halogen atom; R 3 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 4 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 5 represents a hydrogen atom or a nitro group; R 6 is a hydrogen atom or -OCO-R 7 R represents a group; 7 is an alkyl group, a hydroxyalkyl group having one or more hydroxyl groups, an alkenyl group, or -R 8 -OCO-R 9 group, further comprising R 8 is -C n H 2n - represents a hydrocarbon (n=2 or more) consisting of R 9 represents an alkyl group.) 2. A method for cultivating plants, comprising spraying a preparation containing as an active ingredient at least one compound selected from 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-amino-3-chloro-1,4-naphthoquinone, shikonins, and alkanins, during the seedling stage of the plants.

3. The method for cultivating a plant according to claim 2, wherein the shikonins are at least one selected from shikonin, deoxyshikonin, acetylshikonin, isobutyrylshikonin, α-methyl-n-butylshikonin, isovalerylshikonin, β-hydroxyisovalerylshikonin, β,β-dimethylacrylshikonin, and β-acetoxyisovalerylshikonin, and the alkanines are at least one selected from alkanine, deoxyalkanine, acetylalkanine, isobutyrylalkanine, α-methyl-n-butylalkanine, isovalerylalkanine, β-hydroxyisovalerylalkanine, β,β-dimethylacrylshikonin, and β-acetoxyisovalerylalkanine.

4. The method for cultivating a plant according to any one of claims 1 to 3, which is used for reducing deterioration in the quality of a harvested product of a plant or for increasing the harvested product of a plant.

5. The method for cultivating a plant according to any one of claims 1 to 3, wherein the plant is a plant of the order Poaceae or the order Cucurbitaceae.

6. Use of a compound having a quinone skeleton represented by the following general formula (I), excluding 2-methyl-1,4-naphthoquinone, for reducing deterioration in the quality of harvested products of a plant or for increasing the yield of a plant, wherein the compound is sprayed during the seedling stage of the plant. (In the formula, R 1 is a hydrogen atom, a hydroxyl group, a halogen atom, a methyl group, an alkenyl group, an alkoxy group (excluding a methoxy group), or -CHR 6 -CH2CH=C(CH3) 2 R represents a group; 2 represents a hydrogen atom or a halogen atom; R 3 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 4 represents a hydrogen atom, a hydroxyl group, or a nitro group; R 5 represents a hydrogen atom or a nitro group; R 6 is a hydrogen atom or -OCO-R 7 R represents a group; 7 is an alkyl group, a hydroxyalkyl group having one or more hydroxyl groups, an alkenyl group, or -R 8 -OCO-R 9 group, further comprising R 8 is -C n H 2n - represents a hydrocarbon (n=2 or more) consisting of R 9 represents an alkyl group.) 7. Use of at least one compound selected from 1,4-naphthoquinone, 5-hydroxy-1,4-naphthoquinone, 5,8-dihydroxy-1,4-naphthoquinone, 2-hydroxy-1,4-naphthoquinone, 5-hydroxy-2-methyl-1,4-naphthoquinone, 2,3-dichloro-1,4-naphthoquinone, 2,3-dichloro-5,8-dihydroxy-1,4-naphthoquinone, 2,3-dichloro-5-nitro-1,4-naphthoquinone, 2,3-dichloro-6-nitro-1,4-naphthoquinone, 2-methoxy-1,4-naphthoquinone, 2-amino-3-chloro-1,4-naphthoquinone, shikonins, and alkanins for reducing deterioration of plant harvested products or for increasing plant harvested products, wherein the compound is applied during the seedling stage of the plant.

8. The use according to claim 6 or 7, wherein the plant is a plant of the order Poaceae or Cucurbitaceae.

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