Method for cultivating forest seedlings, and method for producing seeds of forest seedlings.

Abstract

This invention provides methods for cultivating forest seedlings that can be grown efficiently. [Solution] A method for cultivating forest seedlings, wherein the forest seedlings are grown in a cultivation space within a facility, the facility is an outer wall made of a light-transmitting covering material with a total light transmittance of 75% or more that surrounds the forest seedlings, and has an opening that can be opened and closed and a light-shielding cover, the cultivation method includes an opening treatment in which the closing start date is set to 5 days or more before the expected flowering date of the forest seedlings and the facility is kept open for 30 days or more until immediately before the closing start date, a temperature adjustment treatment in which the opening is closed to block foreign pollen and heat the inside of the facility during the closing period from the closing start date to the end of the flowering period, and a temperature rise suppression treatment in which the irradiation of light into the inside of the facility is blocked by the light-shielding cover, the shielding in the temperature rise suppression treatment is performed on days when the maximum daily temperature inside the facility exceeds 35°C during the entire period in which the forest seedlings are grown inside the facility.

Description

Technical Field

[0001] The present invention relates to a method for raising forest seedlings and a method for producing seeds of forest seedlings.

Background Art

[0002] In the seed production of forest trees such as Japanese cedar and Japanese cypress, the establishment of seed orchards that realize efficient production has been promoted. Non-Patent Document 1 describes that in a miniature seed orchard, cultivation management is carried out by trunk cutting and pruning of seed trees, fertilization, weeding, pest control, promotion of flowering such as gibberellin administration, artificial crossing, and the like.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a demand for a technology that enables the raising of forest tree seedlings and the production of seeds thereof more efficiently than the technology of Non-Patent Document 1.

[0005] An object of the present invention is to provide a method for raising forest seedlings that can efficiently raise forest seedlings, and a method for producing seeds of forest seedlings that enables stable seed production.

Means for Solving the Problems

[0006] According to the present invention, the following is provided.

[0007] (1) A method for raising forest seedlings, which comprises raising forest seedlings in a cultivation space inside a facility, The facility is a facility that surrounds the forest seedlings with an outer wall made of a light-transmitting covering material with a total light transmittance of 75% or more, and the outer wall has an opening that can be opened and closed, and the outer wall has an opening and closing light-shielding cover that is attached to the outside of the outer wall. The aforementioned breeding method is The closing date for the aforementioned forest seedlings is set to be at least 5 days before the expected flowering date, and the opening treatment is maintained for at least 30 days until immediately before the closing date. During the closure period from the start date of the closure until the end of the flowering period, the openings are closed to block foreign pollen and the inside of the facility is heated to control the temperature, and A temperature rise suppression treatment that blocks light irradiation into the interior of the facility using the aforementioned light-shielding cover, Includes, The shielding in the temperature rise suppression treatment is performed on days when the maximum daily temperature inside the facility exceeds 35°C, throughout the entire period during which the forest seedlings are grown inside the facility. Methods for cultivating forest seedlings. (2) The method for cultivating forest seedlings as described in (1), further comprising irrigating twice or more times a day during the period from May to October of the time when the forest seedlings are cultivated. (3) The method for cultivating forest seedlings according to (1) or (2), wherein the facility is equipped with an insect-proof net stretched over the opening. (4) A method for cultivating forest seedlings according to any one of items (1) to (3), further comprising applying an insecticide to the forest seedlings at least once every two months during the period from May to August of the time the forest seedlings are cultivated. (5) A method for cultivating forest seedlings according to any one of items (1) to (4), wherein the total light transmittance of the covering material is 80% or more. (6) A method for cultivating forest seedlings according to any one of items (1) to (5), wherein the light-blocking rate of the light-blocking cover is 30% or more. (7) A method for cultivating forest seedlings according to any one of (1) to (6), further comprising allowing the forest seedlings to flower during the period for cultivating the forest seedlings, and performing artificial pollination after the start of flowering. (8) A method for producing seeds of forest seedlings, comprising cultivating the forest seedlings by the method for cultivating forest seedlings described in any one of items (1) to (7), and collecting seeds from the forest seedlings. [Effects of the Invention]

[0008] The present invention provides a method for cultivating forest seedlings that can efficiently grow forest seedlings, and a method for producing seeds for forest seedlings that enables stable seed production. [Modes for carrying out the invention]

[0009] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and may be implemented with modifications as appropriate without departing from the scope of the claims and equivalents of the present invention.

[0010] (Mountain seedling) The forest seedlings grown using the cultivation method of the present invention can be woody plant seedlings. Examples of woody plants include plants of the genus Cryptomeria (such as Japanese cedar (Cryptomeria japonica)), plants of the genus Chamaecyparis (such as Japanese cypress (Chamaecyparis obtusa)), plants of the family Pinaceae (such as plants of the genus Pinus (Pinus thunbergii)), plants of the genus Larix (such as Japanese larch (Larix kaempferi) and Larch (Larix gmelinii)), plants of the genus Abies (such as Sakhalin fir (Abies sachalinensis)), plants of the genus Eucalyptus, plants of the genus Prunus (such as cherry (Prunus spp.), plum (Prunus mume), and Nanking cherry (Prunus Examples include plants of the genus Mangifera (such as Mangifera indica), Acacia, Myrica, Quercus (such as Quercus acutissima), Vitis, Malus, Rosa, Camellia (such as Camellia sinensis), Jacaranda (such as Jacaranda mimosifolia), Persea (such as Persea americana), Pyrus (such as Pyrus serotina Rehder and Pyrus pyrifolia), and Santalum (such as sandalwood; Santalum album). Of these, gymnosperms such as plants of the genus *Cryptomeria*, *Chamaecyparis*, *Pinus*, and *Larch* are preferred.

[0011] When forest seedlings undergo temperature control treatment, their age is usually one year or older, preferably two years or older. There is no upper limit, but it is generally acceptable if they are 10 years or younger, preferably 8 years or younger, and more preferably 6 years or younger.

[0012] The height of forest seedlings during temperature control treatment is usually 50 cm or more, preferably 100 cm or more, or 120 cm or more, and more preferably 150 cm or more. This allows the effects of applying environmental stress and administering flower bud differentiation promoters to be fully exerted, enabling efficient flowering promotion. The upper limit is usually 300 cm or less, preferably 250 cm or less, or 220 cm or less, and more preferably 200 cm or less. Therefore, the height of forest seedlings is usually 50 to 300 cm, preferably 100 to 250 cm or 120 to 220 cm, and more preferably 150 to 200 cm.

[0013] Forest seedlings may be individuals propagated asexually by methods such as cuttings or grafting, or individuals propagated from seeds, such as seedlings grown from seed, but cuttings or grafted seedlings are preferred.

[0014] (facility) In the cultivation method of the present invention, forest seedlings are grown in a cultivation space within a specific facility. The facility is one in which the forest seedlings are surrounded by an outer wall made of a light-transmitting covering material with a total light transmittance of 75% or more. By growing the seedlings in a facility, undesirable influences on growth due to climate can be reduced, and foreign pollen can be suppressed, so that cultivation conditions can be easily managed and the method of the present invention can be successfully implemented. Examples of facilities include agricultural greenhouses, greenhouses, artificial sunlight rooms, and other facilities that can seal off the cultivation space inside from the outside air.

[0015] Examples of light-transmitting coating materials include agricultural PO film (made of polyolefin resin) and agricultural vinyl film (made of polyvinyl chloride). The coating material is preferably of the scattering light type, such as having an uneven surface (e.g., a textured film). The total light transmittance of the coating material is 75% or more, preferably 80% or more. The haze of the coating material is usually 10% or more, preferably 20% or more, and more preferably 30% or more, but is not particularly limited.

[0016] As the facility, one having an openable and closable opening on its outer wall is used. Examples of the opening include an openable and closable opening such as a window provided on the ceiling portion and / or side portion of the facility, and a structure that can be opened and closed by having a structure capable of being opened by rolling up a covering material provided on the ceiling portion and / or side portion of the facility.

[0017] Preferably, the facility is provided with an insect-proof net stretched over the opening. The insect-proof net is a structure that has a mesh structure, thus allowing easy air circulation therethrough, while restricting the passage of objects having dimensions larger than the mesh interval. The insect-proof net may be provided in a form covering the entire surface of the opening. In addition, for the insect-proof net provided on the part of the opening that functions as an access port for workers to enter and exit, it may be configured to be open only for a very short opening time for workers to enter and exit, and to cover the entire surface of the opening during other periods. By having such an insect-proof net, it is possible to restrict organisms of the size of insects from entering through the opening, thereby preventing adverse effects on forest tree seedlings caused by harmful organisms such as stink bugs, and suppressing the intrusion of foreign pollen carried by organisms such as insects, so that reliable crossbreeding between specific tree species can be achieved, and high-quality seeds free of foreign DNA contamination can be efficiently obtained.

[0018] As the insect-proof net, known members such as a net made of polyolefin (for example, polyethylene) can be used. The mesh interval of the insect-proof net can be set within a range that does not significantly impair air permeability and can effectively suppress the entry and exit of harmful organisms and pollen-carrying organisms. Specifically, in the insect-proof net having a grid-like mesh structure, the mesh interval is preferably 3 mm or more, while preferably 7 mm or less, more preferably 6 mm or less, and even more preferably 5 mm or less.

[0019] As the facility, one having an openable and closable light-shielding cover externally mounted on the outer wall thereof is used. The term "externally mounted on the outer wall" refers to installation in a form that covers the outer wall from the outside of the space enclosed by the outer wall. Examples of the openable and closable installation of the light-shielding cover include a structure in which the light-shielding cover externally mounted on the ceiling portion and / or side surface portion of the facility can be rolled up to release the light-shielding state, so that the structure is made openable and closable. By closing the openable and closable light-shielding cover to cover the outer wall, it becomes possible to perform adjustment for suppressing temperature rise inside the facility due to solar irradiation.

[0020] Examples of the light-shielding cover include non-woven fabrics (for example, sheets obtained by heating and bonding ultrafine polyethylene fibers (for example, fiber diameter 0.5 to 10 μm)), light-shielding nets (leno weave, raschel weave, plain weave, aluminum net), cheesecloth (made of vinylon, polyethylene, polyester, etc.), and combinations thereof. The light-shielding rate of the light-shielding cover can be, for example, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, or 90% or more.

[0021] (Processing in the cultivation method) The cultivation method of the present invention includes the following processing steps. Opening treatment: The closing start date is set to be 5 or more days before the scheduled flowering date of forest tree seedlings, and the open state is maintained for 30 days or more immediately before the closing start date. Temperature adjustment treatment: During the closing period from the closing start date to the end of the flowering period, the openings are closed to block foreign pollen and heat the inside of the facility. Temperature rise suppression treatment: Light irradiation into the inside of the facility is shielded by the light-shielding cover.

[0022] (Pre-stage of the opening treatment) The cultivation of forest seedlings before being subjected to the open treatment may be carried out within the facility for implementing the method of the present invention, or in other facilities or outdoors. For example, the forest seedlings may be continuously cultivated within the facility from the time of cuttings, grafting, or germination. Alternatively, cuttings, grafting, or germination of the forest seedlings may be carried out in other facilities or outdoors, and then the forest seedlings may be transplanted into the facility for implementing the method of the present invention and subjected to the open treatment and other treatments. However, in order to obtain the effects of the present invention more effectively, it is preferable to cultivate the forest seedlings within the facility for implementing the method of the present invention for more than one year before the start of the open treatment, and to perform temperature rise suppression treatment throughout the entire cultivation period within such facility.

[0023] (Opening process and temperature control process) In the open treatment, the closure start date is set at least 5 days before the expected flowering date of the forest seedlings, and the open state is maintained for at least 30 days until just before the closure start date. In the temperature control treatment, during the closure period from the closure start date to the end of the flowering period, the openings are closed to block foreign pollen and the inside of the facility is heated. By performing this series of treatments, the flowering of the forest seedlings can be promoted. In addition, the closure suppresses the entry of foreign pollen, enabling reliable cross-pollination between specific tree species and efficiently obtaining high-quality seeds free from contamination by foreign DNA.

[0024] The period for maintaining the open state during the opening treatment is 30 days or more, preferably 40 days or more, and more preferably 70 days or more. There is no particular upper limit to the duration of the opening treatment, but it may be, for example, 100 days or less. In order to make the duration of the opening treatment longer than the predetermined number of days, it is necessary to predict and set the expected flowering date at least 5 days in advance of the predetermined number of days. The expected flowering date can be set by appropriately predicting the flowering date based on the type of forest seedling being grown and the climatic conditions during the growing period. For example, if the forest seedling is a Japanese cedar, the expected flowering date is usually early to mid-February, so the opening period is usually in winter (November to early January), and the closing start period is usually from mid-January to early February. Also, if the forest seedling is a Japanese cypress, the expected flowering date is usually early to mid-March, so the opening period is usually in winter (November to mid-February), and the closing start period is usually from mid-February to early March.

[0025] Furthermore, in order to set the start date of closure, it is preferable to set the expected flowering date more accurately. For example, the expected flowering date can be set by continuously observing the state of the tips of the female flowers of the forest seedlings and predicting that flowering will occur at least 5 days after the tips begin to open. The start date of closure is at least 5 days before the expected flowering date set in this way, preferably at least 7 days before, and more preferably at least 10 days before. There is no particular upper limit to the period between the start date of closure and the expected flowering date, but it may be, for example, 15 days or less.

[0026] In temperature control treatment, the period for closing the openings may include the period until the end of the flowering period, i.e., until the point when the female flowers lose their pollination ability. Closing the openings until this point can promote seed formation and suppress contamination. The loss of pollination ability can be detected by observing the cessation of micropyle sap secretion from the female flowers. Specifically, the closing period may be ended on the day when the cessation of micropyle sap secretion is confirmed, or approximately 1 to 5 days after that day. After the closing period ends, the openings may be reopened if necessary.

[0027] Even after these processes are completed, the forest seedlings can continue to be grown inside the facility until the time for the opening treatment and temperature control treatment during the flowering season of the following year, or until the forest seedlings are shipped.

[0028] (Temperature rise suppression treatment) Temperature rise suppression treatment: Light is blocked from entering the facility using a light-blocking cover. This blocking is carried out on days when the maximum daily temperature inside the facility exceeds 35°C throughout the entire period in which the forest seedlings are grown inside the facility.

[0029] Specifically, during the growing period, the temperature inside the facility is monitored, the daily maximum temperature is determined, and if there are days when the temperature is expected to rise and the temperature inside the facility is expected to exceed 35°C, the facility's exterior walls are covered from the outside with a light-blocking cover on those days to block sunlight from entering the facility, thereby suppressing the rise in temperature.

[0030] More specifically, during the summer months when outside temperatures are high, there are many days when the temperature inside the facility is expected to exceed 35°C. In addition, during the aforementioned closure period, thermal energy easily accumulates inside the facility, so there are many days when the temperature inside the facility is expected to exceed 35°C. Such periods when high temperatures are expected include the summer period from June to October and the closure period from February to March for the cultivation of cedar seedlings in Japan; and the summer period from June to October and the closure period from March to April for the cultivation of cypress seedlings in Japan. By applying temperature rise suppression treatment during these periods, undesirable phenomena such as the death of forest seedlings can be avoided, and good forest seedlings can be cultivated.

[0031] By performing this temperature rise suppression treatment, it becomes possible to suppress the average maximum temperature, particularly during the summer and during the closed period, to a desired level below a certain point. The average maximum temperature for a given period is the average value of the highest temperatures during the daytime (24 hours starting at midnight) on each day during that period. Even after performing the temperature rise suppression treatment, the maximum daytime temperature inside the facility on a given day during that period may still exceed 35°C. However, by suppressing the average maximum temperature for that period to a level below a certain point, undesirable phenomena such as the death of forest seedlings can be avoided, and good forest seedlings can be cultivated. Specifically, the average maximum temperature inside the facility during the summer and closed periods can be kept below 35°C. In addition to the temperature rise suppression treatment using light-shielding covers, temperature control inside the facility may also be performed using air conditioning equipment as needed.

[0032] (Flowering promotion treatment) In the method for cultivating forest seedlings of the present invention, any additional steps may be performed in addition to the steps described above. An example of an optional process is a flowering promotion treatment to accelerate the flowering of forest seedlings. Examples of flowering promotion treatments include inducing environmental stress and administering flower bud differentiation promoters.

[0033] Examples of environmental stresses include root zone control, drought stress, salt stress, high temperature stress, and light / darkness stress. From the standpoint of ease of control, root zone control and drought stress are preferred. Pruning and stem cutting treatments can also promote branch formation, and thus are expected to promote flowering.

[0034] Examples of flower bud differentiation promoters include plant hormones such as gibberellin and cytokinin, as well as fertilizers such as slow-release fertilizers with a high phosphorus content. While either one of these can be used, it is more preferable to use both in combination.

[0035] The timing of applying environmental stress and administering flower bud differentiation promoters can be determined at an appropriate time according to each treatment.

[0036] (Artificial insemination treatment) Another example of an optional process is artificial pollination. Artificial pollination can further increase seed production efficiency. It is preferable to perform artificial pollination continuously from immediately after the start of flowering through the flowering period, and in the case of gymnosperms, it is even preferable to perform it before micropyle sap secretion.

[0037] Artificial pollination can be a process of artificially bringing pollen into contact with female flowers (for example, by applying, scattering, spraying, blowing, injecting, or immersing). Specific examples include bringing male flowers close to female flowers and directly sprinkling pollen from the male flowers; applying or injecting pollen onto female flowers using a pollen-holding device such as a brush, cotton swab, or feather broom; blowing pollen onto female flowers using a pollen-blowing device such as a pollen gun, power sprayer, or fan; and scattering, spraying, or immersing female flowers in a pollen suspension.

[0038] Pollen used in artificial pollination can be prepared by separating and purifying it from male flowers. The male flowers may be from the same individual as the female flower being pollinated, or from a different individual. From the viewpoint of obtaining seeds with desired genetic information, it is preferable that the pollen is derived from an individual being grown in a closed indoor environment. However, from the viewpoint of increasing the germination rate, it is preferable to use pollen collected from a seedling different from the female flower when dispersing pollen to the female flower. Furthermore, in addition to the artificial pollination process described later, if pollination by wind or other means between adjacent individuals is expected, it is preferable to arrange multiple individuals in the indoor environment so that individuals with different genetic information are adjacent to each other. For example, it is preferable to arrange one individual with certain genetic information surrounded by eight individuals with different genetic information. Methods for separating and purifying pollen from male flowers include, for example, directly aspirating it from the male flowers using equipment such as a suction device (e.g., a vacuum cleaner), or harvesting the male flowers, drying them at low temperature as needed, crushing them to obtain a crude product, and then shaking it using a sieve.

[0039] (Application of insecticides) Another example of an optional process is the application of insecticides to forest seedlings. The application of insecticides can suppress undesirable effects caused by harmful organisms, such as those that cause insect damage and those that transmit invasive pollen. It is preferable to apply insecticides during the period when forest seedlings are grown in a facility and when these harmful organisms are abundant. In Japan, this period is generally from May to August, so by spraying insecticides in the facility at a frequency of once every two months or more during this period, good insecticide application can be achieved.

[0040] (Other training conditions) In the method for cultivating forest seedlings of the present invention, cultivation conditions other than the treatment described above can be determined according to the general cultivation conditions for forest seedlings. Examples of these are as follows.

[0041] (irrigation) Except for the period during which drought stress is applied as described above, the amount of irrigation water given to one plant of the genera Cryptomeria and Chamaecyparis per day is usually 0.5 to 5 L or 1 to 4.5 L, with 1 to 4 L being preferred. At this time, the moisture content of the growing medium is usually between pF 1.5 and pF 2.3. Examples of irrigation methods include, but are not limited to, drip irrigation, overhead irrigation, and bottom irrigation.

[0042] In a preferred example, irrigation may be performed more than twice a day during the period from May to October, which is the entire period in which forest seedlings are grown in the facility. Specifically, the daily amount of irrigation mentioned above may be divided into two or more portions, and these divided amounts may be used for irrigation each day. For example, if applying a daily irrigation amount of 4L per individual plant by irrigating twice a day, 2L of irrigation can be applied twice a day, in the morning and evening. By performing such irrigation more than twice a day from May to October, undesirable phenomena such as the wilting of forest seedlings can be avoided, and better quality forest seedlings can be grown. During the other period, from November to April, irrigation may be performed once a day to simplify the process, but it may also be done more than twice a day.

[0043] (Spacing between individual units) When processing multiple individuals, there are no particular restrictions on the arrangement of each individual, but it is preferable that the spacing between adjacent individuals be approximately 0.5 to 2 m x 0.5 to 2 m, and more preferably approximately 0.7 to 1.8 m x 0.7 to 1.8 m.

[0044] (fertilization) In addition to the slow-release fertilizers listed above as flower bud differentiation promoters, other fertilizers can be applied as needed to promote the growth of forest seedlings. There are no particular restrictions on the type of fertilizer; it may be a fast-acting fertilizer or a slow-release fertilizer. The fertilizer may also be inorganic or organic, and chemical fertilizers are preferably used.

[0045] The components contained in the fertilizer are not particularly limited, but examples include inorganic components, silver ions, antioxidants, carbon sources, vitamins, amino acids, and plant hormones other than gibberellins, which can serve as sources of nutrients for plants. The form of the fertilizer is not particularly limited and may be solid (e.g., powder, granules) or liquid (e.g., liquid fertilizer).

[0046] Examples of inorganic components include essential elements such as nitrogen, phosphorus, and potassium, and trace elements such as sulfur, calcium, magnesium, iron, manganese, zinc, boron, molybdenum, chlorine, iodine, and cobalt, as well as inorganic salts containing these elements. Examples of such inorganic salts include potassium nitrate, ammonium nitrate, ammonium chloride, sodium nitrate, potassium monohydrogen phosphate, sodium dihydrogen phosphate, potassium chloride, potassium sulfate, ammonium sulfate, magnesium sulfate, ferrous sulfate, ferric sulfate, manganese sulfate, zinc sulfate, copper sulfate, sodium sulfate, calcium chloride, magnesium chloride, boric acid, molybdenum trioxide, sodium molybdate, potassium iodide, cobalt chloride, and their hydrates. Among the essential elements, it is preferable that the nitrogen and / or potassium content is greater than the phosphorus content.

[0047] Examples of antioxidants include ascorbic acid and sulfites, with ascorbic acid being preferred. Ascorbic acid has low persistence in the culture medium, thus helping to suppress environmental pollution.

[0048] Examples of carbon sources include compounds such as carbohydrates like sucrose and their derivatives; organic acids like fatty acids; and primary alcohols like ethanol.

[0049] Examples of vitamins include biotin, thiamine (vitamin B1), pyridoxine (vitamin B4), pyridoxal, pyridoxamine, calcium pantothenate, inositol, nicotinic acid, nicotinamide, and riboflavin (vitamin B2).

[0050] Examples of amino acids include glycine, alanine, glutamic acid, cysteine, phenylalanine, and lysine.

[0051] (Fertilization method) The fertilization method is not particularly limited and can be set to suit the fertilizer used. For example, it can be done by scattering, applying, or spraying an appropriate amount of fertilizer onto the support of the forest seedlings and / or onto the forest seedlings themselves. The timing of fertilization is not particularly limited, but February is preferred. The number of fertilizations is usually once, and two or fewer is preferred. However, the EC value of the growing medium can be monitored, and additional fertilizer may be applied as needed to bring the EC value to a desired value such as 0.3 to 0.8.

[0052] (cultivating soil) The growing medium can be any commonly used material, such as natural soils like sand and soil (e.g., akadama soil, kanuma soil). Other examples of growing mediums include artificial soils such as rice husk charcoal, coconut fiber, vermiculite, perlite, peat moss, glass beads, and coco peat; porous molded products such as foamed phenolic resin and rock wool; and solidifying agents (e.g., agar or gellan gum). At least one of these may be used in place of natural soil, or in combination with natural soil.

[0053] (temperature, humidity, light conditions) Other conditions for growing forest seedlings (e.g., temperature, humidity, light) can be set appropriately depending on the plant species, and may be natural conditions or artificially controlled.

[0054] The temperature during indoor cultivation is usually 35°C or lower after the treatment described above, but it may temporarily reach higher temperatures, such as 43°C or lower. The indoor temperature may be controlled to a specific temperature during the day, night, or both. The daytime temperature is usually 15-35°C, preferably 20-35°C. The nighttime temperature is usually 10-25°C, preferably 10-20°C, and more preferably 15-20°C.

[0055] (Methods of seed production) By applying the cultivation method of the present invention described above to forest seedlings, flowering and fruiting of the forest seedlings can be promoted, and as a result, seeds can be collected. Seed collection can be carried out by conventional methods from the cones produced after flowering. [Examples]

[0056] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention.

[0057] (Example 9) Japanese cedar seedlings were grown inside a closed-type agricultural greenhouse. Nine cedar seedlings (1 year old, 80cm tall) from different strains were planted in each of the nine 46L harvesting containers (535mm wide x 370mm long x 305mm high (outer dimensions), 477mm wide x 320mm long x 288mm high (inner dimensions), transplanted to larger containers as needed to avoid excessively inhibiting plant growth; soil composition: coco peat: small-grained akadama soil: small-grained kanuma soil = 1:1:1, fertilizer used: High Control 085 360-day type (N:P:K = 10:18:15, J-Cam Agri Co., Ltd.)) which contained growing medium, and were grown in an agricultural greenhouse from January 2022.

[0058] The agricultural greenhouse (TSK House: manufactured by Toyotane Co., Ltd.) is a round-roofed greenhouse with a retractable skylight (Rentenso®: Toto Kogyo Co., Ltd.), measuring 7.2m wide x 23m deep x 4-5m high. The exterior walls of the greenhouse are constructed of a covering material (agricultural PO film: Tokan Ace Pear-textured (Tokan Kogyo Co., Ltd.): total light transmittance 82%, haze 51%). In addition, a retractable shading cover (Slim White 90 (Nippon Wide Cross Co., Ltd.): shading rate approximately 90%) is installed on the outside of the greenhouse's exterior walls.

[0059] The covering material on the side walls of the greenhouse, and the shading cover on the outside of them, were designed to be able to be opened and closed by rolling them up. Therefore, the greenhouse's skylight and the rollable side walls functioned as openable openings, and the shading cover on the outside functioned as an openable external shading cover. Insect netting with a mesh spacing of 4 mm was stretched over the openings, thereby preventing organisms larger than the mesh spacing from entering or exiting the openings, even when the openings were open, except for very short periods of opening for workers to enter and exit.

[0060] The spacing between individual cedar seedlings within the greenhouse was adjusted so that there was one seedling per 1.5m x 1.5m square area.

[0061] During the growing period, from May to August, insecticides were sprayed every two months. Specifically, spraying was done twice, in June and August. The insecticide used was Ortran® DX granules, with a spraying rate of 2g per forest seedling.

[0062] Between July and August 2022, 80-100 ml of a 100 ppm aqueous solution of Sumitomo Gibberellin Powder (manufactured by Sumitomo Chemical Co., Ltd., registered with the Ministry of Agriculture, Forestry and Fisheries, registration number 24247) was sprayed onto the branches of each individual Japanese cedar tree.

[0063] During the growing season, watering was performed using drip irrigation. From May to October, watering was performed twice a day, with the daily water volume divided into two applications. From November to April, watering was performed once a day. The amount of water per seedling was 2 liters per day from July to August 2022 to induce drought stress. During other periods, the amount was 1 liter per day.

[0064] The EC value of the growing medium during the cultivation of Japanese cedar seedlings was monitored, and the amount of top dressing fertilizer was adjusted so that the EC value was between 0.3 and 0.8. The EC value was measured by accurately weighing 20g of the sample into a beaker, adding 100ml of distilled water, stirring and standing for 2 minutes, and measuring the electrical conductivity of the supernatant using a conductivity meter (Horiba ES-51, electrode: immersion-type conductivity electrode 9382-10D).

[0065] During the growing season, the temperature inside the greenhouse was monitored, and the daily maximum temperature was recorded. From June to October 2022, temperatures were expected to rise, and there were days when the temperature inside the greenhouse was expected to exceed 35°C. On those days, the outer walls of the greenhouse were covered with shading covers to block sunlight from entering the greenhouse. As a result, the average maximum temperature inside the greenhouse from June to October 2022 was 35°C.

[0066] Until the closing start date was set, the openings in the outer walls of the greenhouse and the shading covers were left open. By consulting records of flowering dates from previous years and continuously observing the condition of the tips of the female flowers of the cedar seedlings, the expected flowering date was set, and the closing start date was set 12 days prior to that. The expected flowering date was set to February 1, 2023, and the closing start date was set to January 20, 2023. On the closing start date, the openings in the outer walls of the greenhouse were closed completely. Because the temperature inside the greenhouse rose due to the closure of the openings, and there were concerns that it would exceed 35°C, the outer walls of the greenhouse were further covered with shading covers from the outside starting on February 4, 2023, to block sunlight from entering the greenhouse. Flowering was confirmed from February 5, 2023, so from that day onward, pollen was collected by sucking it from the male flowers every day, and the pollen from 9 seedlings was purified by shaking it together using a sieve. Artificial pollination was performed by spraying the pollen onto the female flowers of 9 seedlings using a pollen gun. On March 25, 2023, no more micropyle sap secretion was observed from the female flowers. On March 28, 2023, the shading covers were rolled up to remove the light blocking, and the openings in the outer walls were opened. The average maximum temperature inside the greenhouse during the period from February to March 2023 was 25°C.

[0067] The cultivation process continued, and on October 30, 2023, the number of dead seedlings was counted to determine the mortality rate. The total mass of the seeds to date was also weighed.

[0068] (Comparative Example 1) Except for the following changes, the same procedure as in Example 1 was performed to cultivate cedar seedlings, and the mortality rate and total seed mass were evaluated. The method of covering the shading cover was changed to a format where a sheet was installed along the outer wall on the inside of the greenhouse, thereby blocking sunlight from reaching the cedar seedlings on the inside of the greenhouse's outer wall.

[0069] In Comparative Example 1, temperature rise suppression treatment was performed during the same periods as in Example 1, from June to October and from February to March. However, the average maximum temperature inside the greenhouse in August reached 50°C, resulting in an 80% seedling mortality rate.

[0070] (Examples 1-8 and Comparative Examples 2-4) Except for the following changes, the same procedure as in Example 9 was followed to cultivate cedar seedlings, and the mortality rate and total seed mass were evaluated. • In February and March 2023, no light shielding was performed using light-shielding covers after the start date of closure (Comparative Examples 2 and 4). • During June to October 2022, no light shielding was performed using a light-blocking cover on days when temperatures rose (Comparative Examples 3 and 4). From May to October, irrigation was performed once per day, with the same amount of water used per day (Examples 1, 4, and 5, and Comparative Example 4). • No insect netting was used (Examples 1-2 and 5-6, and Comparative Example 4). • Insecticides were sprayed only once in June, and no spraying was performed in August (Example 7). • Insecticide spraying was limited to once in August, and no spraying was performed in June (Example 8). • No insecticides were sprayed (Examples 1-4 and Comparative Example 4).

[0071] (Example 18) Except for the following changes, the same procedure as in Example 9 was followed to cultivate cypress seedlings, and the mortality rate and total seed mass were evaluated. Instead of using cedar seedlings, we used cypress seedlings (80cm tall). Regarding gibberellin administration, instead of spraying gibberellin powder, Sumitomo Gibberellin Paste (manufactured by Sumitomo Chemical Co., Ltd., registered with the Ministry of Agriculture, Forestry and Fisheries, No. 24248) was administered once during the same period as the gibberellin administration period in Example 9. Administration was performed by peeling the bark from the base of the branch of each individual plant, injecting the paste, and securing it with grafting tape. Based on records of typical flowering dates and continuous observation of the condition of the tips of female flowers on cypress seedlings, a projected flowering date was set, and the closure start date was set 8 days prior to that date. The projected flowering date was set for March 5, 2023, and the closure start date was set for February 25, 2023. The shading cover was also closed from February 25. Flowering was confirmed from March 10, 2023. On April 20, 2023, the secretion of micropyle sap from the female flowers ceased. On April 25, 2023, the shading cover was rolled up to remove the light blocking, and the openings in the outer wall were opened. The average maximum temperature inside the greenhouse during the period from February to April 2023 was 25℃.

[0072] (Comparative Example 5) Except for the following changes, the same procedure as in Example 18 was followed to cultivate cypress seedlings, and the mortality rate and total seed mass were evaluated. The method of covering the shading cover was changed to a format where a sheet was installed along the outer wall on the inside of the greenhouse, thereby blocking sunlight from reaching the cypress seedlings on the inside of the greenhouse's outer wall.

[0073] In Comparative Example 5, temperature rise suppression treatment was performed during the same periods as in Example 1, from June to October and from February to March. However, the average maximum temperature inside the greenhouse in August reached 50°C, resulting in an 80% seedling mortality rate.

[0074] (Examples 10-17 and Comparative Examples 6-8) Except for the following changes, the same procedure as in Example 18 was followed to cultivate cedar seedlings, and the mortality rate and total seed mass were evaluated. • From February to March 2023, no light shielding was performed using light-shielding covers after the start date of closure (Comparative Examples 6 and 8). • During June to October 2022, no light shielding was performed using a light-blocking cover on days when temperatures rose (Comparative Examples 7 and 8). From May to October, irrigation was performed once per day, with the same amount of water used per day (Examples 10, 13, and 14, and Comparative Example 8). • No insect netting was used (Examples 10-11 and 14-15, and Comparative Example 8). • Insecticide spraying was limited to once in June, and no spraying was performed in August (Example 16). • Insecticide spraying was limited to once in August, and no spraying was performed in June (Example 17). • No insecticides were sprayed (Examples 10-13 and Comparative Example 8).

[0075] Tables 1 to 4 show summaries and results of the examples and comparative examples. In Tables 1 to 4, seed mass is shown as a relative value with Example 9 as 100% for the cedar seedling examples (Examples 1 to 9 and Comparative Examples 1 to 4), and as a relative value with Example 18 as 100% for the cypress seedling examples (Examples 10 to 18 and Comparative Examples 5 to 8). "Average maximum temperature inside the greenhouse from February to March or February to April" is shown for February to March for the cedar seedling examples, and for February to April for the cypress seedling examples.

[0076] [Table 1]

[0077] [Table 2]

[0078] [Table 3]

[0079] [Table 4]

[0080] As is clear from the results above, when the cultivation method of the present invention is implemented with specific open treatment, temperature control treatment and temperature rise suppression treatment, the mortality rate is low and efficient cultivation and seed production can be carried out, resulting in the collection of many seeds.

Claims

1. A method for cultivating forest seedlings, in which the seedlings are grown in a cultivation space within a facility, The facility is a facility that surrounds the forest seedlings with an outer wall made of a light-transmitting covering material with a total light transmittance of 75% or more, and the outer wall has an opening that can be opened and closed, and the outer wall has an opening and closing light-shielding cover that is attached to the outside of the outer wall. The aforementioned breeding method is The closing date for the aforementioned forest seedlings is set to be at least five days before the expected flowering date, and the opening treatment is maintained for at least 30 days until immediately before the closing date. During the closure period from the start date of the closure until the end of the flowering period, the openings are closed to block foreign pollen and the inside of the facility is heated to control the temperature, and A temperature rise suppression treatment that blocks light irradiation into the interior of the facility using the aforementioned light-shielding cover, Includes, The shielding in the temperature rise suppression treatment is performed on days when the maximum daily temperature inside the facility exceeds 35°C, throughout the entire period during which the forest seedlings are grown inside the facility. Methods for cultivating forest seedlings.

2. The method for cultivating forest seedlings according to claim 1, further comprising irrigating the seedlings at least twice a day during the period from May to October of the cultivation period.

3. The method for cultivating forest seedlings according to claim 1, wherein the facility is equipped with an insect-proof net stretched over the opening.

4. The method for cultivating forest seedlings according to claim 1, further comprising applying an insecticide to the forest seedlings at least once every two months during the period from May to August of the time the forest seedlings are being cultivated.

5. The method for cultivating forest seedlings according to claim 1, wherein the total light transmittance of the covering material is 80% or more.

6. The method for cultivating forest seedlings according to claim 1, wherein the light-blocking rate of the light-blocking cover is 30% or more.

7. The method for cultivating forest seedlings according to claim 1, further comprising allowing the forest seedlings to flower during the period for cultivating the forest seedlings, and performing artificial pollination after the start of flowering.

8. A method for producing seeds of forest seedlings, comprising cultivating the forest seedlings by the method for cultivating forest seedlings described in any one of claims 1 to 7, and collecting seeds from the forest seedlings.

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