Planting soil for plants, cultivation kit comprising the planting soil, cultivation method using the planting soil, and seedling of plants with the planting soil

Abstract

The present application relates to a plant culture soil, which comprises: a fungus of the genus Cladophialophora, and soil, which is any one of a strongly acidic organic cultivation soil, a strongly acidic conventional cultivation soil, and a weakly acidic to neutral organic cultivation soil, or a plant culture soil, which comprises: a fungus of Exophiala sp. SK47 or a mutant strain thereof, and a strongly acidic organic cultivation soil or a strongly acidic conventional cultivation soil; a plant cultivation method using the culture soil; and a plant seedling with the culture soil.

Description

Technical Field

[0001] This invention relates to plant growing soil, cultivation kits containing growing soil, cultivation methods using growing soil, and plant seedlings with growing soil. Background Technology

[0002] According to the Food and Agriculture Organization of the United Nations, approximately 40% of the world's total arable land is capable of successfully producing crops. Currently, about 5 million hectares (ha) of arable land deteriorate annually. Without new measures related to arable land protection, it is projected that by 2050, the world's per capita arable land will decrease to one-quarter of the arable land level in 1960. Therefore, it is necessary to shift from conventional farming methods that prioritize productivity to sustainable agriculture that prioritizes the environment.

[0003] In conventional farming practices that prioritize productivity, sometimes only specific types of crops are cultivated in particular plots of land. However, the continuous cultivation of the same crops in the same locations can lead to the proliferation of certain pathogens (e.g., pests or fungi), disrupting the ecosystem balance and consequently hindering crop production. This is because most pathogens are host-specific to crops. Therefore, as a solution to this problem, cultivation methods using root endophytic fungi are known. Root endophytic fungi (DSE) are beneficial microorganisms that live in a symbiotic relationship with plants, using the roots as their parasitic site.

[0004] As a cultivation method using useful microorganisms in a symbiotic relationship with plants, for example, the following method has been reported: a cultivation method in which Cladophialophora chaetospira SK51, a fungus, is symbiotic with strawberry seedlings that have been induced to develop wilt disease by fungi of the genus Fusarium (e.g., Wiwiek Harsonowati et al., The Effectiveness of a Dark Septate Endophytic Fungus, Cladophialophorachaetospira SK51, to Mitigate Strawberry Fusarium Wilt Disease and With Growth Promotion Activities, Front. Microbiol., 2020. Apr. 15, Vol. 11, Art. 585). Summary of the Invention

[0005] However, conventional farming methods that prioritize productivity are currently the mainstream, while there is limited understanding of sustainable agriculture that prioritizes the environment.

[0006] The present invention was made in view of the above circumstances. The object of the present invention is to provide: a potting soil for plants that can promote plant growth or flower bud formation under conditions that are not normally suitable for plant growth, a cultivation kit containing the potting soil, a cultivation method using the potting soil, and seedlings of plants with potting soil.

[0007] The specific methods used to solve the above problems include the following approaches.

[0008] <1> A plant growing medium comprising:

[0009] Fungi of the genus Cladophialophora, and

[0010] Soil, which is any one of strongly acidic organic cultivation soil, strongly acidic conventional cultivation soil, and weakly acidic to neutral organic cultivation soil.

[0011] <2> According to the above <1> The plant culture soil, wherein the fungus of the genus Cladophialophora is Cladophialophora chaetospira.

[0012] <3> A plant growing medium comprising:

[0013] Fungi, specifically Exophiala sp. SK47 or its mutant strains, and

[0014] Strongly acidic organic cultivation soil or strongly acidic conventional cultivation soil.

[0015] <4> According to the above <1> ~ <3> The potting soil for any one of the plants, wherein the strong acidity is above pH 3 and below pH 5.

[0016] <5> According to the above <1> ~ <4> The potting soil for any one of the plants, wherein the plant is a fruit or vegetable.

[0017] <6> A cultivation kit comprising the above <1> ~ <5> The potting soil and the plant body of any one of the plants described above.

[0018] <7> A method for cultivating a plant, comprising: a cultivation step, wherein the above-mentioned... <1> ~ <5> The plant is cultivated in the potting soil of any one of the plants described above.

[0019] <8> According to the above <7> The cultivation method for the plant, in the cultivation process, includes cultivating plants that form flower buds under high temperature and long day conditions, while plants that form flower buds under low temperature and short day conditions are cultivated under high temperature and long day conditions.

[0020] <9> According to the above <8> The cultivation method for the plant, wherein the high temperature and long day conditions are: the temperature is within the range of 15°C to 25°C, and the light duration is within the range of 12 hours to 24 hours.

[0021] <10> A seedling of a plant in potting soil, comprising: the above-mentioned... <1> ~ <5> The potting soil for any one of the plants, and the seedlings of the plant.

[0022] Invention Effects

[0023] According to the present invention, it is possible to provide: a potting mix for plants that can promote plant growth or flower bud formation under conditions that are generally unsuitable for plant growth; a cultivation kit containing said potting mix; a cultivation method using said potting mix; and plant seedlings. Attached Figure Description

[0024] Figure 1 It is a photo showing the growth status of strawberries.

[0025] Figure 2 This is a chart showing the dried quality of the above-ground parts of a strawberry plant.

[0026] Figure 3 This is a chart showing the dried quality of strawberry roots.

[0027] Figure 4 This is a chart showing the number of strawberry fruits formed.

[0028] Figure 5 It is a chart showing the number of days from the formation of strawberry flower buds. Detailed Implementation

[0029] The following describes one embodiment of the present invention in detail. However, the present invention is not limited to the following embodiment. In the following description, the constituent elements (including element steps, etc.) are not essential unless specifically stated otherwise. The same applies to numerical values ​​and their ranges; they do not limit the present invention.

[0030] In this invention, the term "process" can include not only processes that are independent of other processes, but also processes that can achieve their purpose if they cannot be clearly distinguished from other processes.

[0031] In this invention, the numerical range represented by “~” includes the values ​​recorded before and after “~” as the lower limit and upper limit, respectively.

[0032] In the stepped numerical ranges described in this invention, the upper or lower limit of one numerical range can be replaced by the upper or lower limit of another stepped numerical range. Furthermore, in the numerical ranges described in this specification, the upper or lower limit can be replaced by the values ​​shown in the embodiments.

[0033] In this invention, the content of each component in the composition refers to the total content of the multiple substances present in the composition, unless otherwise specified.

[0034] The first embodiment of plant cultivation soil

[0035] The plant cultivation soil of the first embodiment of the present invention comprises:

[0036] Fungi, belonging to the genus Cladophialophora, and

[0037] Soil, which is any one of strongly acidic organic cultivation soil, strongly acidic conventional cultivation soil, and weakly acidic to neutral organic cultivation soil.

[0038] A culture medium containing fungi of the genus Cladophialophora and any of the following soil types: strongly acidic organic soil, strongly acidic conventional soil, and weakly acidic to neutral organic soil, which can promote plant growth or flower bud formation under conditions that are not normally suitable for plant growth.

[0039] The role of the potting soil for the plants in the first embodiment is unclear, but it is presumed to be as follows.

[0040] Fungi of the genus *Cladophialophora* contained in the potting soil extend their hyphae in a net-like pattern around the plant roots. Furthermore, if the fungi attach to the surface of the plant roots, they form appressoriums, which then penetrate and become fixed within the root cells, thus establishing a symbiotic relationship between the fungi and the plant.

[0041] If a symbiotic relationship is established, for example in the case of organic cultivation soil, the fungi present in the organic soil can provide the plants with amino acids or proteins that are not efficiently utilized by the plants as nutrients. As a result, the plants can easily absorb nutrients such as nitrogen and phosphorus and use them for their own growth. Furthermore, for example, in the case of strongly acidic soil, or when plants are cultivated under conditions where the temperature or light duration is unsuitable for the plants, the fungi confer tolerance to these environmental stresses on the plants.

[0042] That is, even in organic cultivation soil, highly acidic soil, or under conditions such as temperature or light duration that are unsuitable for plant growth or flower bud formation, it is possible to promote plant growth or flower bud formation by using the plant culture soil of the first embodiment.

[0043] It should be noted that the present invention is not limited in any way by the above-described presumed mechanism.

[0044] Furthermore, in this invention, promoting plant growth can be confirmed by an increase in the dry weight of the above-ground parts or an increase in the dry weight of the roots.

[0045] In this invention, promoting flower bud formation in plants can be confirmed by either an increase in the number of flower buds formed or a decrease in the number of days until flower bud formation. Alternatively, in this invention, promoting flower bud formation in plants can be confirmed by either an increase in the number of fruits formed or a decrease in the number of days until fruit formation. It should be noted that in this invention, "fruit" does not refer only to true fruits, but also includes, for example, false fruits such as strawberries and figs.

[0046] Fungi

[0047] (Fungi of the genus Cladophialophora)

[0048] Examples of fungi belonging to the genus Cladophialophora involved in this invention include Cladophialophora chaetospira, Cladophialophora arxii, Cladophialophora tortuosa, Cladophialophora floridana, Cladophialophora psammophila, Cladophialophora boppii, Cladophialophora hachij oensis, Cladophialophora carrionii, Cladophialophora tumbae, and Cladophialophora tumulicola. From the viewpoint of further enhancing the effects of this invention, Cladophialophora chaetospira is preferred.

[0049] The preferred strain of Cladophialophora chaetospira is Cladophialophora chaetospira SK51 (hereinafter also referred to as SK51 or SK51 strain) or a mutant strain thereof, which is deposited under the receiving number NITE BP-03539. The SK51 strain is deposited at the Patent Microbial Collection Center of the National Institute for Technical Evaluation, located at 2-5-8 Kamazusa, Kisarazu City, Chiba Prefecture, Japan (deposit date: November 7, 2022).

[0050] More preferably, the mutant strain described above is one that exhibits an effect on promoting plant growth or flower bud formation equal to or greater than that of the SK51 strain under conditions generally unsuitable for plant growth. Examples of methods for introducing the mutation include treatment with chemicals such as nitroso compounds (e.g., nitrosamines or nitrosoguanidines) or alkylating agents (e.g., EMS; ethyl methanesulfonate), ultraviolet radiation, or radiation exposure, but are not limited to these methods. Whether the obtained mutant strain exhibits an effect equal to or greater than that of the SK51 strain is determined by measuring the promoting effect of the obtained mutant strain on plant growth or flower bud formation and comparing it with the measurement results of the SK51 strain.

[0051] (Other fungi)

[0052] The plant culture soil of the first embodiment may contain fungi other than those exemplified above, to the extent that it does not impair the effect of promoting plant growth or flower bud formation. It should be noted that there are no particular limitations on the types of other fungi.

[0053] (Fungi content)

[0054] In the plant culture soil of the first embodiment, from the viewpoint of further maximizing the effects of the present invention, the fungi are preferably prepared in a manner containing 5% to 10% by mass of the fungal-containing material. It should be noted that, in the present invention, the fungal-containing material can be obtained by the following method. Specifically, 10 mL of a pre-culture solution of fungi (e.g., 1 × 10⁻⁶) is used. 5 hyphal fragments / ml ~ 1×10 6 Hyphal fragments / ml) are added to a sterilized plastic bag containing sterilized culture material (e.g., a mixture of 100g wheat bran, 100g rice bran, 300g leaf mold, and 340mL sterilized water). The mixture of the pre-culture solution and culture material is then incubated in a chamber for 3–4 weeks to obtain material containing the fungi.

[0055] It should be noted that, for example, the number of fungi in the culture soil of the plant in the first embodiment can be set to 10. 3 The hyphalfragments / g or higher. Furthermore, since the plant and fungi have a symbiotic relationship, the number of fungi in the culture soil increases as the plant cultivation time progresses. The aforementioned number of fungi is preferably the number at the moment when plant cultivation begins in the plant culture soil of the first embodiment (e.g., the moment when plant seeds are sown in the plant culture soil, or the moment when additionally cultivated 3-leaf seedlings are transplanted and established in the plant culture soil, etc.).

[0056] It should be noted that the number of fungi in the culture soil of the plant of the first embodiment can be determined by the following method: spreading the fungi on a 50% CMMY agar medium and then culturing at 23°C for 7 days.

[0057] (Morphology of fungi)

[0058] In the plant culture medium of the first embodiment, the fungi can be in any stage of their life cycle. For example, the fungi can be mycelium or sporophyte.

[0059] <Soil>

[0060] (Organic cultivation soil)

[0061] The organic cultivation soil involved in this invention refers to soil that does not contain pesticides and chemical fertilizers. It should be noted that conventional cultivation soil (i.e., inorganic cultivation soil) can be cited as the opposite of organic cultivation soil, which refers to soil that contains pesticides and / or chemical fertilizers.

[0062] (Highly acidic soil)

[0063] From the viewpoint of further maximizing the effects of the present invention, the strongly acidic soil involved in the present invention is preferably soil with a pH of 3 or higher and less than pH 5, and more preferably soil with a pH of 3 or higher and less than pH 4.

[0064] In this invention, weakly acidic soil is soil with a pH of 5 or higher and a pH of less than 7.

[0065] In this invention, weakly acidic to neutral soil is soil with a pH of 5 or higher and a pH of 7 or lower, which is the pH that is usually used as conventional cultivation soil.

[0066] It should be noted that, in this invention, the pH of the soil can be determined by the following method. Specifically, the pH of the soil can be confirmed by mixing soil and distilled water at a sample:solution ratio of 1:2.5 (preferably 1:5 in the case of soil with high organic matter content), stirring with a reciprocating vibrator for more than 1 hour, and then measuring the pH of the suspension by the glass electrode method at 23°C ± 2°C.

[0067] Furthermore, from the viewpoint of further maximizing the effects of the present invention, the plant cultivation soil of the first embodiment comprises:

[0068] Fungi of the genus Cladophialophora, and

[0069] The soil is any one of strongly acidic organic cultivation soil, strongly acidic conventional cultivation soil, and weakly acidic to neutral organic cultivation soil, preferably used as a potting soil to promote plant growth or to promote plant flower bud formation.

[0070] <Other Ingredients>

[0071] The plant culture soil of the first embodiment may contain components other than the soil and the fungi. Examples of other components include, for instance, solid media (e.g., amino acids such as leucine, methionine, or phenylalanine, or sucrose), liquid media (e.g., water, sterile water, sterile distilled water, or physiological saline), components used to stabilize and maintain the fungi involved in this invention in the culture soil (e.g., stabilizers or isotropic agents), and components used to promote the proliferation of the fungi involved in this invention (e.g., malt extract culture medium (MEB), CM malt yeast culture medium (CMMY) (preferably a mixture of 8.5g CM agar, 15g agar, 10g malt extract, 1g yeast extract, and 1L sterile water), wheat bran, rice bran, or leaf mold, etc.), but are not limited thereto. It should be noted that the content of other components in the plant culture soil of the first embodiment is not particularly limited as long as it does not impair the effect of promoting plant growth or flower bud formation.

[0072] <Plants>

[0073] The potting soil of the first embodiment can promote plant growth or flower bud formation under conditions that are generally unsuitable for plant growth, making it particularly excellent as a potting soil for fruit and vegetable plants. Alternatively, the plant species used in the potting soil can be plants of the Rosaceae family (e.g., strawberry, apricot, plum, cherry, plum, pear, Chinese pear, Japanese pear, loquat, peach, apple, prune, nectarine, karin, or quince). It should be noted that, in the potting soil of the first embodiment, strawberry is more preferably the plant species.

[0074] Plant cultivation soil according to the second embodiment

[0075] The plant cultivation soil of the second embodiment of the present invention comprises:

[0076] Fungi, specifically Exophiala sp. SK47 or its mutant strains, and

[0077] Strongly acidic organic cultivation soil or strongly acidic conventional cultivation soil.

[0078] Culture media containing fungi such as Exophiala sp. SK47 or its mutants, as well as strongly acidic organic or conventionally acidic culture media, are culture media that can promote plant growth or flower bud formation under conditions that are not normally suitable for plant growth.

[0079] The role of the plant culture soil in the second embodiment is not clear, but similar to the first embodiment, by having the fungus Exophiala sp. SK47 or its mutant strain symbiotic with the plant, even under conditions such as organic cultivation soil or strongly acidic soil, or temperature or light duration unsuitable for plant growth or flower bud formation, the plant growth or flower bud formation can be promoted by cultivating the plant in the culture soil containing the fungus.

[0080] It should be noted that the present invention is not limited by the above-described presumed mechanism.

[0081] Fungi

[0082] (Exophiala sp. SK47 or its mutant strains)

[0083] The Exophiala sp. SK47 (hereinafter also referred to as SK47 or SK47 strain) involved in this invention is deposited at the National Institute for Technical Evaluation, Patent Microbial Collection Center, located at 2-5-8 Kamazusa, Kisarazu City, Chiba Prefecture, Japan, with accession number NITE BP-03540 (deposit date: November 7, 2022).

[0084] More preferably, the mutant strain of Exophiala sp. SK47 is one that exhibits an effect on promoting plant growth or flower bud formation equal to or greater than that of the SK47 strain under conditions generally unsuitable for plant growth. Methods for introducing mutations into Exophiala sp. SK47 include, but are not limited to, treatment with chemicals such as nitroso compounds (e.g., nitrosamines or nitrosoguanidines) or alkylating agents (e.g., EMS; ethyl methanesulfonate), ultraviolet radiation, or radiation. Whether the resulting mutant strain exhibits an effect equal to or greater than that of the SK47 strain is determined by measuring the promoting effect of the resulting mutant strain on plant growth or flower bud formation and comparing it with the measured results for the SK47 strain.

[0085] The descriptions of (other fungi), (fungus content), (fungus morphology), (organic cultivation soil), and (strongly acidic soil) in the plant cultivation soil of the second embodiment include definitions, examples, and preferred methods, which are the same as those described in the items of "Plant Cultivation Soil of the First Embodiment" above.

[0086] It should be noted that, from the viewpoint of further maximizing the effects of the present invention, the plant culture soil of the second embodiment preferably contains fungi of Exophiala sp. SK47 or its mutant strains, and strongly acidic conventional cultivation soil, and is used as a culture soil for promoting plant growth. Alternatively, from the viewpoint of further maximizing the effects of the present invention, the plant culture soil of the second embodiment preferably contains fungi of Exophiala sp. SK47 or its mutant strains, and strongly acidic organic cultivation soil or strongly acidic conventional cultivation soil, and is used as a culture soil for promoting flower bud formation in plants.

[0087] The descriptions of <other components> and <plants> in the plant culture soil of the second embodiment include definitions, examples, and preferred methods, which are the same as those described in the items of "Plant Culture Soil of the First Embodiment" above.

[0088] Cultivation Kit

[0089] The cultivation kit of the present invention comprises a plant culture medium of the first embodiment or a plant culture medium of the second embodiment, and a plant body. According to the present invention, a cultivation kit is available that can promote plant growth or flower bud formation even under conditions that are generally unsuitable for plant growth.

[0090] <Plant cultivation soil of the first embodiment or plant cultivation soil of the second embodiment>

[0091] The description of the plant culture soil of the first embodiment or the second embodiment of the cultivation kit of the present invention includes definitions, examples, and preferred methods, etc., which are the same as the descriptions recorded in the above-mentioned "Plant Culture Soil of the First Embodiment" or "Plant Culture Soil of the Second Embodiment".

[0092] <Plant Body>

[0093] In the cultivation kits of the present invention, the plant body may be, for example, a seed or a seedling of a plant. The seed of a plant may be, for example, a seed that has developed young roots or young shoots. The seedling of a plant may be, for example, a seedling with only cotyledons, a seedling at the 3-leaf stage, or a seedling at a stage of 3 or more, a seedling or a seedling obtained by propagation from a parent plant or a seedling of a previous generation (e.g., a seedling of a runner), or a cloned seedling propagated by cuttings or the like.

[0094] Regarding the plant in the cultivation kit of the present invention, the description of the plant species includes definitions, examples, and preferred methods, which are the same as the description of the <plant> described in the above-mentioned item "Plant Cultivation Soil of the First Embodiment".

[0095] Plant Cultivation Methods

[0096] The plant cultivation method of the present invention includes a cultivation step of cultivating plants using the plant culture soil of the first embodiment or the plant culture soil of the second embodiment. According to the plant cultivation method of the present invention, plant growth or flower bud formation can be promoted even under conditions that are generally unsuitable for plant growth.

[0097] <Cultivation Procedures>

[0098] (Plant potting soil)

[0099] The description of the plant cultivation soil type in the plant cultivation method of the present invention includes definitions, examples, and preferred methods, which are the same as those described in the above-mentioned "Plant Cultivation Soil of the First Embodiment" or "Plant Cultivation Soil of the Second Embodiment".

[0100] (plant)

[0101] The description of the plant species in the plant cultivation method of the present invention includes definitions, examples, and preferred methods, which are the same as the description of <plant> described in the above-mentioned item "Plant Cultivation Soil of the First Embodiment".

[0102] (Cultivation conditions)

[0103] From the viewpoint of further enhancing the effects of the present invention, the cultivation process in the plant cultivation method of the present invention preferably includes a process of cultivating plants that will form flower buds under low temperature and short day conditions under high temperature and long day conditions.

[0104] It should be noted that the plant that forms flower buds under low temperature and short-day conditions is specifically preferred to form flower buds regardless of day length when the temperature is above 5°C but below 15°C (i.e., low temperature), form flower buds only under short-day conditions when the temperature is above 15°C but below 25°C (i.e., high temperature), and not form flower buds regardless of day length when the temperature is above 25°C. It should be noted that in this invention, short-day conditions refer to a day length of 0 hours or more but less than 12 hours.

[0105] Examples of plants that form flower buds under low-temperature conditions include strawberries, broad beans, peas, broccoli, and cauliflower. Examples of plants that form flower buds under short-day conditions include grains such as strawberries, soybeans, and rice, as well as flowering plants such as chrysanthemums and morning glories.

[0106] In the plant cultivation method of the present invention, the high temperature condition is preferably in the range of air temperature exceeding 15°C and below 25°C, more preferably in the range of exceeding 20°C and below 25°C, and even more preferably 23°C. In the plant cultivation method of the present invention, the long day condition is preferably in the range of light duration exceeding 12 hours and below 24 hours, more preferably in the range of exceeding 14 hours and below 24 hours, and even more preferably 16 hours.

[0107] It should be noted that in this invention, the temperature can be controlled by the following method. Specifically, the temperature in the artificial weather chamber used for plant cultivation is maintained at a constant temperature, and the cultivation location is rotated every few days to ensure temperature uniformity.

[0108] <Supply Process>

[0109] The plant cultivation method of the present invention may include a supply step. The supply step is the process of supplying the soil with fungi of the genus Cladophialophora, or Exophiala sp. SK47 or its mutant strains.

[0110] (Supply Methods)

[0111] The preferred method for supplying fungi to the soil is to mix the soil and fungi. When supplying fungi to the soil, the <other components> described in the above-mentioned item "Plant Cultivation Soil of the First Embodiment" may also be supplied to the soil.

[0112] (Supply Period)

[0113] The fungi can be supplied to the soil at the time of sowing plant seeds, transplanting 3-leaf seedlings into the soil, or planting the seedlings in the soil. Alternatively, in soil pre-mixed with fungi, the fungi can be supplied by sowing plant seeds, transplanting 3-leaf seedlings, or planting the seedlings in the soil. It should be noted that, from the viewpoint of further maximizing the effects of the invention, the fungi can be supplied to the culture soil not only during the supply process but also during the cultivation process.

[0114] (Supply)

[0115] From the viewpoint of further maximizing the effects of the present invention, the fungi supplied to the soil are preferably supplied as a material containing fungi in a manner comprising 5% to 10% by mass in the plant culture soil. It should be noted that, in the present invention, the method for obtaining the material containing fungi is as described in the item "Plant Culture Soil of the First Embodiment" above.

[0116] It should be noted that the microorganisms supplied to the soil, for example, can be set at 10 in the culture medium. 3 hyphal fragments / g or more.

[0117] Seedlings of plants with potting soil

[0118] The plant seedlings with culture soil involved in this invention are plant seedlings with culture soil containing the plant culture soil involved in this invention and the plant seedlings.

[0119] According to the present invention, it is possible to obtain seedlings of plants that can promote plant growth or flower bud formation even under conditions that are not normally suitable for plant growth.

[0120] The preferred embodiment of the plant seedling with culture soil involved in this invention is the same as the description of the <plant> described in the above-mentioned item "Plant Culture Soil of the First Embodiment".

[0121] [Example]

[0122] The present invention will be described in more detail below through embodiments. However, the invention is not limited to these embodiments unless it departs from its spirit. It should be noted that unless otherwise specified, "parts" refers to a quantity based on mass. Similarly, "%" also refers to a quantity based on mass.

[0123] Supply Process

[0124] <Preparation of materials containing fungi>

[0125] As fungi included in the plant culture medium, three root endophytic fungi were prepared: *Exophiala sp. SK47* (hereinafter also referred to as SK47.), *Exophiala pisciphila SK48* (hereinafter also referred to as SK48.), and *Cladophialophora chaetospira SK51* (hereinafter also referred to as SK51.). It should be noted that *Exophiala sp. SK47* is deposited at the National Institute for Technical Evaluation Patent Microbial Collection Center located at 2-5-8 Kamazuta, Kisarazu City, Chiba Prefecture, Japan, with accession number NITE BP-03540. *Cladophialophora chaetospira SK51* is deposited at the National Institute for Technical Evaluation Patent Microbial Collection Center located at 2-5-8 Kamazuta, Kisarazu City, Chiba Prefecture, Japan, with accession number NITE BP-03539. The three fungi were cultured for 4 weeks at 23°C with shaking at 120 rpm in 500 mL flasks, each containing 250 mL of 2% malt extract medium (MEB). After culturing, mycelia of the three types were collected by filtering the culture medium and washed with sterile distilled water until the liquid containing the collected mycelia became clear, ensuring no contamination from the MEB medium. Then, to prevent contamination, the obtained mycelia and sterile distilled water were mixed separately for 1 minute at the lowest speed using a stirrer and laminar flow to obtain pre-culture solutions. The survival rate of each fungus in the pre-culture solution was determined by directly spreading the pre-culture solution containing mycelia onto 50% CMMY agar medium and incubating at 23°C for 7 days.

[0126] It should be noted that the large-scale production of each type of fungus is carried out using the following method. Specifically, 10 mL of the pre-culture medium of each type of fungus (1×10⁻⁶) is... 6 Hyphal fragments / ml were added separately to sterilized plastic bags containing sterilized culture material (a mixture of 100g wheat bran, 100g rice bran, 300g leaf mold, and 340mL sterilized water). The mixture of pre-culture solutions and culture material for each fungus was then cultured in a chamber for 3–4 weeks to prepare materials containing each fungus.

[0127] <Soil Preparation>

[0128] Prepare organic soil (made from Sakata seeds) as organic cultivation soil (i.e., soil for sustainable agriculture models). Prepare Powerful Soil N50 for strawberry seedlings (manufactured by Takara Sangyo Co., Ltd.) as conventional cultivation soil (also known as inorganic cultivation soil, i.e., soil for conventional farming methods models).

[0129] The prepared organic cultivation soil has a pH of 6.0 to 6.5, and is therefore considered a "slightly acidic to neutral organic cultivation soil". On the other hand, an appropriate amount of peat moss (manufactured by Tokawa Heiwa Farm) is mixed into the prepared organic cultivation soil to prepare a "strongly acidic organic cultivation soil" with a pH of 3.8 to 4.3.

[0130] The prepared conventional cultivation soil has a pH of 6.0 to 6.5, and is therefore designated as a "slightly acidic to neutral conventional cultivation soil". On the other hand, an appropriate amount of peat moss (manufactured by Tokawa Heiwa Farm) is mixed into the prepared conventional cultivation soil to prepare a "strongly acidic conventional cultivation soil" with a pH of 3.8 to 4.3.

[0131] It should be noted that the pH of the soil was determined by the following method. Specifically, the pH of the soil was determined by mixing soil and distilled water at a sample:solution ratio of 1:2.5 (1:5 when using soil with high organic matter content), stirring with a reciprocating shaker for more than 1 hour, and then measuring the pH of the suspension by the glass electrode method at 23℃±2℃.

[0132] All of the above soil samples were sterilized twice under pressure at 121°C for 30 minutes.

[0133] <Supplying fungi to the soil>

[0134] In prepared slightly acidic to neutral organic cultivation soil, slightly acidic to neutral conventional cultivation soil, strongly acidic organic cultivation soil, and strongly acidic conventional cultivation soil, a material containing root endophytic fungi of *Exophiala sp. SK47*, *Exophiala pisciphila SK48*, or *Cladophialophorachaetospira SK51* was mixed at 10% by mass in the cultivation soil to prepare the plant cultivation soil of the first embodiment (hereinafter also referred to as the first cultivation soil), the plant cultivation soil of the second embodiment (hereinafter also referred to as the second cultivation soil), the cultivation soil as a comparative example, and the cultivation soil as a reference example. It should be noted that the slightly acidic to neutral conventional cultivation soil used in the reference example is generally soil under conditions suitable for plant growth.

[0135] That is, prepare culture soil under the conditions shown below.

[0136] (Comparative Example 1) Strongly acidic organic cultivation soil

[0137] (Example 1; Second Culture Medium) Strongly acidic organic culture soil and Exophiala sp. SK47

[0138] (Comparative Example 2) Strongly acidic organic cultivation soil and Exophiala pisciphila SK48

[0139] (Example 2; First potting mix) Strongly acidic organic potting soil and Cladophialophorachaetospira SK51

[0140] (Comparative Example 3) Strongly acidic conventional cultivation soil

[0141] (Example 3; Second Culture Medium) Strongly acidic conventional cultivation soil and Exophiala sp. SK47

[0142] (Comparative Example 4) Strongly acidic conventional cultivation soil and Exophiala pisciphila SK48

[0143] (Example 4; First potting mix) Strongly acidic conventional cultivation soil and Cladophialophorachaetospira SK51

[0144] (Comparative Example 5) Slightly acidic to neutral organic cultivation soil

[0145] (Comparative Example 6) Slightly acidic to neutral organic cultivation soil and Exophiala sp. SK47

[0146] (Comparative Example 7) Slightly acidic to neutral organic cultivation soil and Exophiala pisciphila SK48

[0147] (Example 5; First culture medium) Slightly acidic to neutral organic culture soil and Cladophialophorachaetospira SK51

[0148] (Refer to Example 1) Slightly acidic to neutral conventional cultivation soil

[0149] (Refer to Example 2) Slightly acidic to neutral conventional cultivation soil and Exophiala sp. SK47

[0150] (Refer to Example 3) Slightly acidic to neutral conventional cultivation soil and Exophiala pisciphila SK48

[0151] (Refer to Example 4) Slightly acidic to neutral conventional cultivation soil and Cladophialophora chaetospira SK51

[0152] Cultivation Procedures

[0153] <Plant Preparation>

[0154] As a plant, the seeds of the ever-blooming strawberry (Wild Strawberry, Sakata) were used. The surface of the strawberry seeds was sterilized using the method shown below. Specifically, the seeds were immersed in a 70% ethanol solution for 1 minute and 30 seconds, and then in a sodium hypochlorite (1% available chlorine) solution for 1 minute. Next, the seeds were washed three times with sterile distilled water, dried overnight, and then placed on a 1.5% water agar medium and incubated at 23°C to allow germination, allowing them to grow for 4 weeks until the 3-leaf stage.

[0155] Planting in potting soil

[0156] In a pot with a diameter of 6 cm, the prepared culture soil of Examples 1 to 5, Comparative Examples 1 to 7, and Reference Examples 1 to 4 was placed, and strawberries at the 3-leaf stage were planted in the culture soil.

[0157] <Cultivation Conditions>

[0158] Strawberries were transplanted under high-temperature, long-day conditions at a constant temperature of 23°C and a duration of 16 hours, and then cultivated for 150 days. That is, no low-temperature treatment was performed in the cultivation process of this embodiment.

[0159] It should be noted that strawberry flower bud formation is related to temperature and photoperiod length. Strawberries typically form flower buds regardless of photoperiod length when the temperature is above 5°C but below 15°C (i.e., low temperature). Flower buds form only under short-day conditions when the temperature is above 15°C but below 25°C (i.e., high temperature). Flower buds do not form regardless of photoperiod length when the temperature exceeds 25°C. Therefore, strawberries are typically treated with a 15°C low-temperature storage facility to promote flower bud formation, known as low-temperature treatment.

[0160] "evaluate"

[0161] <Strawberry growth status>

[0162] After cultivating the strawberries in potting soil under various conditions, visually observe their growth. Present the results... Figure 1 It should be explained that... Figure 1In the diagram, 'a' represents the growth status in strongly acidic organic cultivation soil, 'b' represents the growth status in strongly acidic conventional cultivation soil, 'c' represents the growth status in slightly acidic to neutral organic cultivation soil, and 'd' represents the growth status in slightly acidic to neutral conventional cultivation soil. The control area represents the culture soil of the control zone that does not contain fungi.

[0163] <Drying quality of above-ground parts>

[0164] After cultivation in potting soil under various conditions, the strawberry plants were removed from their pots and dried at 40°C for 72 hours. The weight of the aboveground parts was then measured. Statistical analysis was performed using SPSS version 20.0 (SPSS, IBM, Armonk, NY, United States), including analysis of variance (ANOVA) and Tukey's test (p < 0.05). The results are presented below. Figure 2 .exist Figure 2 In the bar chart, under the same soil and pH conditions, significant differences are shown between a and b, and between a and c. The vertical axis represents the dry weight (mg) of the aboveground parts of a strawberry plant. The control represents the culture soil of the control area that does not contain fungi.

[0165] In other words, in conventionally acidic growing soil, the presence of SK47 or SK51 as a fungus in the potting mix can promote strawberry growth. Similarly, in organically grown, highly acidic growing soil, the presence of SK51 as a fungus can also promote strawberry growth.

[0166] <Dried quality of roots>

[0167] After cultivation in potting soil under various conditions, the strawberry plants were removed from their pots and dried at 40°C for 72 hours. The root mass was then measured. The results are presented below. Figure 3 It should be noted that the statistical analysis methods and the symbols for a, b, and c are the same as those described in the <Dry Mass of Aboveground Parts> section. The vertical axis represents the dry mass (mg) of roots obtained from a strawberry plant. The control represents the culture soil of the control area that does not contain fungi.

[0168] In other words, in conventionally acidic growing soil, the presence of SK47 or SK51 as a fungus in the potting mix can promote strawberry growth. Similarly, in organically grown, highly acidic growing soil, the presence of SK51 as a fungus can also promote strawberry growth.

[0169] <Number of fruits formed>

[0170] After cultivation in potting soil under various conditions, the number of strawberry fruits formed was counted. The results are presented below. Figure 4 It should be noted that the statistical analysis methods and the symbols for a, b, and c are the same as those described in the <Dry Weight of Aboveground Parts> section. The bar chart of results in conventionally grown soils with slightly acidic to neutral pH shows a significant difference between a and d. It should be noted that s indicates a significant difference, and ns indicates no significant difference. The vertical axis represents the number of fruits obtained from one strawberry plant. The control represents the culture soil from the control area that does not contain fungi.

[0171] That is, in the case of conventionally acidic cultivation soil, if the potting soil contains SK47 or SK51 as a fungus, it can promote strawberry fruit formation. In the case of conventionally acidic cultivation soil, if the potting soil contains SK51 or SK51 as a fungus, it can also promote strawberry fruit formation. Furthermore, in the case of conventionally acidic to neutral organic cultivation soil, if the potting soil contains SK51 as a fungus, it can promote strawberry fruit formation. It should be noted that, as a reference example, in the case of conventionally acidic to neutral cultivation soil (i.e., inorganic cultivation soil), if the potting soil contains SK47, SK48, or SK51 as a fungus, it can promote strawberry fruit formation.

[0172] <Number of days until flower bud formation>

[0173] After cultivating strawberries in potting soil under various conditions, the number of days until flower bud formation was counted. The results are presented below. Figure 5 .exist Figure 5 In the text, the number of days until flower bud formation is displayed as 150 days, which means that at 150 days, 0 flower buds have formed. Figure 5 In the charts below (pH 6.0–6.5), the numbers at the top of each plot represent the number of strawberry individuals out of 8 that developed flower buds. The control plot represents the culture soil in the control area that does not contain fungi.

[0174] That is, in the case of conventionally acidic cultivation soil, if the potting soil contains SK47, SK48, or SK51 as fungi, it can promote the formation of strawberry flower buds. In the case of conventionally acidic to neutral organic cultivation soil, if the potting soil contains SK47 or SK51 as fungi, it can promote the formation of strawberry flower buds. Furthermore, in the case of conventionally acidic to neutral organic cultivation soil, if the potting soil contains SK51 as a fungus, it can promote the formation of strawberry flower buds. It should be noted that, as a reference example, in the case of conventionally acidic to neutral cultivation soil (i.e., inorganic cultivation soil), if the potting soil contains SK47, SK48, or SK51 as fungi, it can promote the formation of strawberry flower buds.

[0175] Based on the above results, it can be concluded that under the high-temperature conditions of a constant 23°C and long-day conditions of 16 hours of light, which prevent sufficient flower bud formation in the control area, the addition of *Exophiala sp. SK47* or *Cladophialophora chaetospira* SK51 to the potting soil can promote strawberry growth or flower bud formation. The promoting effect is particularly significant when *Cladophialophora chaetospira* SK51 is included in the potting soil.

[0176] In other words, the potting soil of the present invention can promote strawberry growth or flower bud formation even under high-temperature, long-day conditions that are generally unsuitable for strawberry cultivation, whether it is organic cultivation soil (i.e., soil from a sustainable agriculture model) or strongly acidic soil (i.e., soil from a cultivable land model). The ability to harvest strawberries under these high-temperature, long-day conditions means that year-round strawberry harvesting becomes possible. Furthermore, the fungi of the present invention exert their effects through symbiosis with plants, thus promoting the growth or flower bud formation of plants other than strawberries.

[0177] The contents of Japanese Patent Application No. 2021-190595, filed on November 24, 2021, are incorporated herein by reference in their entirety. All documents, patent applications, and technical standards described in this specification are incorporated herein by reference to the same extent that they are specifically and separately described therein.

Claims

1. A plant cultivation soil, characterized in that, Include: Fungi, specifically Exophiala sp. SK47 or its mutant strains, and Strongly acidic organic cultivation soil or strongly acidic conventional cultivation soil. The strong acidity is above pH 3 and below pH 5.

2. The plant cultivation soil according to claim 1, wherein, The plant in question is a fruit or vegetable.

3. A cultivation kit, characterized in that, Include: The potting soil and plant body of the plant as described in claim 1 or 2.

4. A method for cultivating a plant, characterized in that, Include: The cultivation process, wherein the plant is cultivated using the potting soil described in claim 1 or 2, The cultivation process includes cultivating plants that form flower buds under low temperature and short day conditions under high temperature and long day conditions. The high-temperature, long-day conditions are defined as follows: the temperature is between 15°C and 25°C, and the daylight hours are between 12 hours and 24 hours.

5. A plant seedling with potting soil, characterized in that, Include: The potting soil for the plant as described in claim 1 or 2, and the seedlings of the plant.

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