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

Abstract

To provide a method for growing forest seedlings, which can efficiently grow forest seedlings. [Solution] A method for cultivating forest seedlings in a cultivation space within a facility, the facility surrounding the forest seedlings with an exterior wall made of a light-transmitting covering material with a total light transmittance of 75% or more, and having an opening that can be opened and closed, and a shading cover, the cultivation method includes an opening process in which the closure start date is set to be at least five days before the expected flowering date of the forest seedlings, and the facility is kept open for at least 30 days until just before the closure start date, a temperature adjustment process in which the opening is closed to block out foreign pollen and heat the facility during the closure period from the closure start date to the end of the flowering period, and a temperature rise suppression process in which the shading cover blocks light from entering the facility, and the shading in the temperature rise suppression process is performed on days when the maximum daily temperature within the facility exceeds 35°C throughout the entire period in which the forest seedlings are cultivated within the facility.

Description

[Technical Field]

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

[0002] The development of seed orchards has been promoted to realize efficient seed production of forest trees such as cedar and cypress. Non-Patent Document 1 describes that in miniature seed orchards, seed trees are grown and managed by pruning, fertilizing, weeding, taking measures against pests and diseases, promoting flowering by administering gibberellin, and artificial cross-pollination. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Mie Prefectural Forestry Research Institute, "Manual for Cedar Seed Production Using the Miniature Seed Orchard Method," March 2016 https: / / www.pref.mie.lg.JP / common / content / 000623014.pdf Summary of the Invention [Problem to be solved by the invention]

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

[0005] An object of the present invention is to provide a method for growing forest seedlings that can efficiently grow forest seedlings, and a method for producing forest seedling seeds that can enable stable seed production. [Means for solving the problem]

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

[0007] (1) A method for growing forest seedlings in a growing space within a facility, The facility is a facility that surrounds the forest seedlings with an exterior wall made of a light-transmitting covering material with a total light transmittance of 75% or more, and has an openable / closable opening in the exterior wall and an openable / closable shading cover hung on the exterior wall, The growing method comprises: An opening treatment in which the closing start date is set to be 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 closing start date; A temperature adjustment process for closing the opening to block foreign pollen and heating the facility during a closure period from the closure start date to the end of the flowering period; and a temperature rise suppression process in which the light-shielding cover blocks light from reaching the inside of the facility; Including, The shielding in the temperature rise suppression treatment is performed on days when the maximum daily temperature in the facility exceeds 35°C throughout the entire period in which the forest seedlings are grown in the facility. How to grow forest seedlings. (2) The method for cultivating forest seedlings according to (1), further comprising watering the seedlings at least twice a day during the period from May to October during which the seedlings are cultivated. (3) A method for cultivating forest seedlings according to (1) or (2), in which the facility is equipped with an insect net stretched over the opening. (4) A method for cultivating forest seedlings according to any one of (1) to (3), further comprising applying an insecticide to the forest seedlings at least once every two months from May to August during the period in which the forest seedlings are cultivated. (5) The method for growing forest seedlings according to any one of (1) to (4), wherein the covering material has a total light transmittance of 80% or more. (6) The method for growing forest seedlings according to any one of (1) to (5), wherein the shading rate of the shading cover is 30% or more. (7) A method for cultivating forest seedlings according to any one of (1) to (6), further comprising causing the forest seedlings to flower during the period in which the forest seedlings are cultivated, and performing an artificial cross-pollination treatment after the flowering begins. (8) A method for producing seeds of forest seedlings, comprising cultivating the forest seedlings by the method for cultivating forest seedlings according to any one of (1) to (7) and harvesting seeds from the forest seedlings. [Effects of the Invention]

[0008] According to the present invention, there are provided a method for growing forest seedlings that can efficiently grow forest seedlings, and a method for producing forest seedling seeds that enables stable seed production. DETAILED DESCRIPTION OF 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 can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0010] (Mountain seedling) The forest seedlings grown by the method of the present invention may be seedlings of woody plants. Examples of woody plants include Cryptomeria plants (such as Cryptomeria japonica), Chamaecyparis plants (such as Chamaecyparis obtusa), Pinaceae plants (such as Pinus thunbergii), Larix plants (such as Larix kaempferi and Larix gmelinii), Abies plants (such as Abies sachalinensis), Eucalyptus plants, and Prunus plants (such as Prunus spp., Prunus mume, and Prunus tomentosa). tomentosa), Mangifera plants (Mango (Mangifera indica), Acacia plants, Myrica plants, Quercus plants (Quercus acutissima, etc.), Vitis plants, Malus plants, Rosa plants, Camellia plants (Camellia sinensis, etc.), Jacaranda plants (Jacaranda mimosifolia, etc.), Persea plants (Avocado (Persea americana), etc.), Pyrus plants (Pyrus serotina Rehder, Pyrus pyrifolia, etc.), and Santalum plants (Sandalwood; Santalum album, etc.). Among these, gymnosperms such as plants of the genus Cryptomeria, plants of the genus Chamaecyparis, plants of the genus Pinus, and plants of the genus Larix are preferred.

[0011] The age of the forest seedlings at the time of temperature adjustment treatment is usually at least 1 year old, preferably at least 2 years old. There is no particular upper limit, but usually it is sufficient if they are 10 years old or less, preferably 8 years old or less, and more preferably 6 years old or less.

[0012] The height of the forest seedlings at the time of temperature adjustment 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 a flower bud differentiation promoter to be fully exerted, enabling efficient promotion of flowering. 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 the 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] The forest seedlings may be individuals propagated asexually by cuttings, grafting, etc., or individuals propagated from seeds, such as seedlings, 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 a facility in which the forest seedlings are surrounded by exterior walls made of a light-transmitting covering material with a total light transmittance of 75% or more. Growing them within the facility reduces undesirable effects of climate on growth and suppresses foreign pollen, making it easy to manage cultivation conditions and enabling the method of the present invention to be implemented effectively. Examples of facilities include agricultural greenhouses, greenhouses, artificial sunlight rooms, and other facilities that can close off the cultivation space inside from the outside air.

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

[0016] The facility to be used has an opening that can be opened or closed in its exterior wall. Examples of the opening include an opening that can be opened or closed, such as a window, provided in the ceiling and / or side of the facility, and a structure that can be opened or closed by rolling up a covering material provided in the ceiling and / or side of the facility.

[0017] Preferably, the facility is provided with an insect net stretched over its openings. The insect net has a mesh structure that allows easy airflow through it while restricting the passage of objects larger than the mesh spacing. The insect net may be provided to cover the entire opening. Furthermore, an insect net provided over an opening that functions as an entrance / exit for workers may be open only for a very short time for workers to enter and exit, and may cover the entire opening at other times. The provision of such an insect net can restrict the entry of insect-sized organisms through the opening, thereby preventing harmful organisms such as stink bugs from adversely affecting forest seedlings. Furthermore, the entry of exotic pollen transmitted by insects and other organisms can be inhibited, enabling reliable crossbreeding between specific tree species and efficiently producing high-quality seeds free of exotic DNA contamination.

[0018] The insect net may be made of a known material such as a polyolefin (e.g., polyethylene) net. The mesh spacing of the insect net may be set within a range that does not significantly impede breathability and effectively prevents harmful organisms and pollinating organisms from entering or exiting. Specifically, in an insect net having a lattice-like mesh structure, the mesh spacing is preferably 3 mm or more, and is preferably 7 mm or less, more preferably 6 mm or less, and even more preferably 5 mm or less.

[0019] The facility has an openable / closable shading cover that is hung on the exterior wall. Hanging on the exterior wall refers to an installation that covers the exterior wall from the outside of the space enclosed by the exterior wall. An example of an openable / closable shading cover is a structure that has a structure that allows the shading cover hung on the ceiling and / or side of the facility to be rolled up to release the shading state, making it openable / closable. By closing the openable / closable shading cover and covering the exterior wall, it is possible to adjust the temperature inside the facility to suppress the rise in temperature caused by sunlight irradiation.

[0020] Examples of light-shielding covers include nonwoven fabrics (e.g., sheets made by heating and bonding polyethylene ultrafine fibers (e.g., fiber diameters of 0.5 to 10 μm)), light-shielding nets (kalami 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] (Treatment in cultivation method) The growing method of the present invention comprises the following processing steps. Open treatment: The closure start date is set at least five 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. Temperature control treatment: During the closure period from the start date of closure to the end of the flowering period, the openings are closed to block out foreign pollen and the facility is heated. Temperature rise suppression treatment: A light-blocking cover blocks light from entering the interior of the facility.

[0022] (Pre-release process) The forest seedlings may be grown in a facility for implementing the method of the present invention before being subjected to the open treatment, or may be grown in another facility or outdoors. For example, the forest seedlings may be grown in the facility continuously from the time of cutting, grafting, or germination of the forest seedlings. Alternatively, the forest seedlings may be grown in another facility or outdoors, and then transplanted into a facility for implementing the method of the present invention and subjected to the open treatment and other treatments. However, to more effectively obtain the effects of the present invention, it is preferable to grow the forest seedlings in a facility for implementing the method of the present invention for at least one year before the start of the open treatment and to subject them to temperature rise suppression treatment throughout the entire growth period in the facility.

[0023] (Opening process and temperature adjustment process) In the open treatment, the closure begins at least five days before the forest seedlings are expected to flower, and the facility remains open 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 opening is closed to block out foreign pollen and the facility is heated. By carrying out this series of treatments, the flowering of forest seedlings can be promoted. Furthermore, closure suppresses the entry of foreign pollen, ensuring reliable cross-pollination between specific tree species and allowing for the efficient production of high-quality seeds free from foreign DNA contamination.

[0024] The period for maintaining the open state in the open treatment is 30 days or more, preferably 40 days or more, and more preferably 70 days or more. The upper limit of the open treatment period is not particularly limited, but can be, for example, 100 days or less. To ensure that the open treatment period is a predetermined number of days or more, 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 cultivation period. For example, if the forest seedling is a cedar, the expected flowering date is usually early to mid-February, so the opening period is usually winter (November to early January), and the closure start period is usually mid-January to early February. Furthermore, if the forest seedling is a cypress, the expected flowering date is usually early to mid-March, so the opening period is usually winter (November to mid-February), and the closure start period is usually mid-February to early March.

[0025] Furthermore, in order to set the closure start date, it is preferable to set the expected flowering date more accurately. For example, the expected flowering date can be set by continuously observing the condition of the tips of the female flowers of forest seedlings and predicting that the tips will begin to open and flower at least five days later. The closure start date is at least five days, preferably at least seven days, and more preferably at least ten days before the expected flowering date thus set. There is no particular limit to the upper limit of the period between the closure start date and the expected flowering date, but it can be, for example, 15 days or less.

[0026] The closing period of the openings during the temperature adjustment treatment can be set to the end of the flowering period, i.e., the period up to the point where the pollination ability of the female flowers is lost. Closing the openings until this point can promote seed formation and suppress contamination. The loss of pollination ability can be detected by observing the end of micropyle secretion from the female flowers. Specifically, the closing period can be ended on the day when it is confirmed that micropyle secretion has ended, or about 1 to 5 days after that date. After the closing period ends, the openings can be opened again if necessary.

[0027] Even after these treatments are completed, the forest seedlings can continue to be grown inside the facility until the time for opening and temperature adjustment treatments at the flowering time 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 with a shading cover. This shading 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 will be monitored, and the daily maximum temperature will be determined. If there are days when the temperature is expected to rise and exceed 35°C inside the facility, the facility will be covered with a light-blocking cover from the outside on days including such high-temperature days, thereby blocking light from reaching the inside of the facility, thereby suppressing temperature rise.

[0030] More specifically, during the summer when outside temperatures are high, there are many days when temperatures inside the facility are expected to exceed 35°C. In addition, during the closed periods mentioned above, thermal energy easily accumulates inside the facility, resulting in many days when temperatures inside the facility are expected to exceed 35°C. Such high-temperature days are expected during the summer months of June to October and the closed period of February to March for the cultivation of Japanese cedar seedlings in Japan; and during the summer months of June to October and the closed period of March to April for the cultivation of Japanese cypress seedlings in Japan. By performing temperature rise suppression treatment during these periods, undesirable phenomena such as the withering and death of forest seedlings can be avoided, enabling the cultivation of healthy forest seedlings.

[0031] By performing such temperature rise suppression treatment, it is possible to suppress the average maximum temperature during the summer and closed periods to a desired, somewhat lower temperature. The average maximum temperature during a certain period is the average maximum temperature during that period for each day (24 hours starting at midnight). Even after performing temperature rise suppression treatment, the daily maximum temperature inside the facility on a certain day during that period may still exceed 35°C. However, by suppressing the average maximum temperature during that period to a somewhat lower temperature, undesirable phenomena such as the death of forest seedlings can be avoided and good forest seedling growth can be achieved. 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 a shading cover, the temperature inside the facility may also be adjusted using air conditioning equipment as needed.

[0032] (Flowering promotion treatment) In the method for growing forest seedlings of the present invention, in addition to the steps described above, any other steps may be carried out. An example of an optional step is a flowering promotion treatment to promote flowering of forest seedlings, which includes applying environmental stress and administering a flower bud differentiation promoter.

[0033] Examples of environmental stresses include rhizosphere control, drought stress, salt stress, high temperature stress, and light-dark stress. From the viewpoint of ease of control, rhizosphere control and drought stress are preferred. Furthermore, pruning and trunk cutting also promote branch formation, which can be expected to promote flowering.

[0034] Examples of flower bud differentiation promoters include plant hormones such as gibberellins and cytokinins, and fertilizers such as slow-release fertilizers with high phosphorus content. Either one of these may be used alone, but it is more preferable to use both in combination.

[0035] The timing of applying environmental stress and administering the flower bud differentiation promoter can be set to an appropriate time depending on each treatment.

[0036] (Artificial breeding treatment) Another example of an optional step is artificial cross-pollination, which can further increase seed production efficiency. Artificial cross-pollination is preferably carried out immediately after the onset of flowering and continuously throughout the flowering period, and in the case of gymnosperms, it is more preferably carried out before micropyle sap is secreted.

[0037] Artificial cross-pollination treatment can be a treatment in which pollen is artificially brought into contact with female flowers (for example, by applying, dusting, spraying, spraying, injecting, or immersing). Specific examples include a method in which male flowers are brought close to female flowers and pollen is directly sprinkled from the male flowers; a method in which pollen is applied or injected into female flowers using an instrument capable of holding pollen, such as a brush, a brazier, or a feather broom; a method in which pollen is sprayed onto female flowers using an instrument capable of spraying pollen, such as a pollen gun, a power sprayer, or an electric fan; and a method in which a pollen suspension is dusted, sprayed, or immersed onto female flowers.

[0038] The pollen used in the artificial cross-pollination treatment can be prepared by separating and purifying male flowers. The male flowers may be male flowers of the same individual as the female flower to be pollinated, or they may be male flowers of a different individual. From the viewpoint of obtaining seeds with the 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 other than the female flower when dispersing pollen to the female flowers. Furthermore, in addition to the artificial cross-pollination treatment described below, if pollination between adjacent individuals by wind pollination or the like is expected, it is preferable to arrange multiple individuals in an indoor environment so that individuals with different genetic information are adjacent to each other. For example, it is preferable to arrange one individual with a certain genetic information surrounded by eight individuals with different genetic information. Methods for separating and purifying pollen from male flowers include, for example, directly sucking the pollen from the male flowers using equipment such as a suction machine (e.g., a vacuum cleaner), or harvesting the male flowers, drying them at low temperature if necessary, and then crushing them to obtain a crude product, which is then shaken using a sieve.

[0039] (Pesticide application) Another example of an optional step is the application of an insecticide to forest seedlings. Application of an insecticide can suppress undesirable effects caused by harmful organisms, such as organisms that cause insect damage and organisms that transmit invasive pollen. The insecticide is preferably applied during the period when the forest seedlings are grown in a facility, when the harmful organisms are most prevalent. In Japan, this period is generally from May to August, and effective application of the insecticide can be achieved by spraying the insecticide in the facility at least once every two months during this period.

[0040] (Other growing conditions) In the method for growing forest seedlings of the present invention, the conditions for growing the seedlings other than the above-mentioned treatments can be determined according to general conditions for growing forest seedlings. Examples of these conditions are as follows.

[0041] (irrigation) Except for the period when the above-mentioned drought stress is applied, the amount of irrigation given to one plant of the genus Cryptomeria japonica or Chamaecyparis obtusa per day is usually 0.5 to 5 L or 1 to 4.5 L, preferably 1 to 4 L. In this case, the moisture content of the culture medium is usually pF 1.5 or more and less than pF 2.3. Examples of irrigation methods include, but are not limited to, drip irrigation, overhead irrigation, and subsurface irrigation.

[0042] In a preferred example, irrigation may be carried out two or more times per day from May to October during the entire period in which forest seedlings are grown in a facility. Specifically, the above-mentioned daily irrigation amount may be divided into two or more portions, and each divided amount may be irrigated per day. For example, when irrigating 4 L per plant per day twice a day, irrigation with 2 L of water per day may be carried out twice a day, in the morning and evening. By irrigating twice or more times a day in this manner from May to October, undesirable phenomena such as the death of forest seedlings can be avoided, and better forest seedling growth can be achieved. During the other periods, from November to April, irrigation may be carried out once a day to simplify the process, but it may also be carried out twice or more times a day.

[0043] (Individual placement interval) When treating multiple individuals, the arrangement of each individual is not particularly limited, but the spacing between adjacent individuals is preferably about 0.5 to 2 m x 0.5 to 2 m, more preferably about 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, fertilization can be carried out as needed, thereby promoting the growth of forest seedlings. The fertilizer is not particularly limited, and may be either a fast-acting fertilizer or a slow-release fertilizer. The fertilizer may also be either an inorganic fertilizer or an organic fertilizer, with chemical fertilizers being preferred.

[0045] The components contained in the fertilizer are not particularly limited, and examples thereof include components that can serve as a source of nutrients for plants, such as inorganic components, silver ions, antioxidants, carbon sources, vitamins, amino acids, plant hormones other than gibberellins, etc. The form of the fertilizer is not particularly limited, and it may be either a solid (e.g., powder, granules) or a 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 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 hydrates thereof. Among the essential elements, it is preferable that the content of nitrogen and / or potassium is greater than the content of phosphorus.

[0047] Examples of antioxidants include ascorbic acid and sulfites, with ascorbic acid being preferred. Ascorbic acid has low residual capacity in the medium and can therefore prevent environmental pollution.

[0048] Examples of carbon sources include compounds such as carbohydrates such as sucrose and their derivatives; organic acids such as fatty acids; and primary alcohols such as 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] Amino acids include, for example, glycine, alanine, glutamic acid, cysteine, phenylalanine, and lysine.

[0051] (Fertilization method) The fertilization method is not particularly limited, and fertilization conditions can be selected according to the fertilizer used. For example, an appropriate amount of fertilizer can be scattered, applied, or sprayed onto the support for the forest seedlings and / or the forest seedlings themselves. The time of fertilization is not particularly limited, but February is preferred. The frequency of fertilization is usually once, preferably twice or less. However, the EC value of the culture soil can be monitored, and additional fertilization can be performed as needed to achieve a desired EC value of 0.3 to 0.8.

[0052] (cultivating soil) The culture medium may be any commonly used medium, such as natural soil such as sand, soil (e.g., Akadama soil, Kanuma soil), etc. Other examples of culture medium include artificial soil 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 selected from these may be used in place of or together with natural soil.

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

[0054] The temperature during indoor cultivation is usually 35°C or lower by carrying out the treatments described above, but may temporarily rise to a higher temperature, such as 43°C or lower. The indoor temperature may be controlled to a specific temperature during the day, at night, or both, with the daytime temperature usually being 15 to 35°C, preferably 20 to 35°C. The nighttime temperature is usually 10 to 25°C, preferably 10 to 20°C, more preferably 15 to 20°C.

[0055] (Seed production method) By applying the above-described cultivation method of the present invention to forest seedlings, flowering and fruiting of the forest seedlings can be promoted, and as a result, seeds can be harvested from the cones produced after flowering in a conventional manner. [Example]

[0056] The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the examples shown below, and can be implemented with any modifications within the scope of the claims of the present invention and their equivalents.

[0057] Example 9 Cedar seedlings were grown in a closed agricultural greenhouse. Nine 46L harvest containers (external dimensions: 535mm wide x 370mm long x 305mm high, internal dimensions: 477mm wide x 320mm long x 288mm high) containing potting soil were used. Plants were replanted into larger containers as necessary to avoid excessively suppressing growth; potting soil composition: coco peat, small Akadama soil, small Kanuma soil = 1:1:1; test fertilizer: High Control 085 360-day type (N:P:K = 10:18:15, J-Cam Agri Co., Ltd.)). A single cedar seedling (1-year-old, 80cm tall) of a different strain was planted in each container and grown in an agricultural greenhouse from January 2022.

[0058] The agricultural greenhouse (TSK House, manufactured by Toyotane Co., Ltd.) was a round-roofed greenhouse with a width of 7.2 m, a depth of 23 m, and a ridge height of 4-5 m, equipped with an openable skylight (Rentenso (registered trademark), manufactured by Toto Kogyo Co., Ltd.). The exterior walls of the greenhouse were constructed with a covering material (agricultural PO film: Tokan Ace Sainjiki (manufactured by Tokan Kogyo Co., Ltd.): total light transmittance 82%, haze 51%). In addition, an openable shading cover (Slim White 90 (manufactured by Nippon Wide Cross Co., Ltd.): shading rate approximately 90%) was installed on the outside of the exterior walls of the greenhouse.

[0059] The covering material on the exterior side walls of the greenhouse and the outer shading cover were both designed to be openable and closable by rolling them up. Therefore, the greenhouse's skylight and the rollable exterior side walls functioned as openable and closable openings, and the outer shading cover functioned as an openable and closable external shading cover. An insect net with a mesh spacing of 4 mm was stretched over the opening, preventing the entry and exit of any creatures larger than the mesh spacing, even when the opening was open, except for the very short periods when it was open for workers to enter and exit.

[0060] The spacing of each individual cedar seedling in the greenhouse was adjusted so that there was one individual in a 1.5m x 1.5m square.

[0061] During the growing period from May to August, insecticide was sprayed once every two months. Specifically, spraying was carried out twice a year, in June and August. Ortran (registered trademark) DX granules were used as the insecticide, and the amount sprayed each time was 2 g 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., Ministry of Agriculture, Forestry and Fisheries Registration No. 24247) was sprayed onto the branches of each individual cedar tree.

[0063] During the growing period, watering was performed by drip irrigation. Watering was performed twice a day from May to October, with the daily amount divided into two doses per day. Watering was performed once a day from November to April. The amount of water per seedling was 2 L per day from July to August 2022, to apply drought stress. The amount of water per seedling was 1 L per day during the rest of the period.

[0064] The EC value of the soil used to grow cedar seedlings was monitored, and the amount of test fertilizer added was adjusted to maintain an EC value of 0.3 to 0.8. EC values ​​were measured by accurately weighing 20 g of sample into a beaker, adding 100 ml of distilled water, stirring for 2 minutes, and measuring the electrical conductivity of the supernatant liquid with a conductivity meter (HORIBA ES-51, electrode: immersion conductivity electrode 9382-10D).

[0065] During the growing period, the temperature inside the greenhouse was monitored to determine the daily maximum temperature. Between June and October 2022, temperatures rose and there were days when temperatures inside the greenhouse were expected to exceed 35°C. On those days, the greenhouse's exterior walls were covered with a shading cover to block light from reaching the inside of the greenhouse. As a result, the average maximum temperature inside the greenhouse between June and October 2022 was 35°C.

[0066] Until the closure start date was set, the openings on the exterior walls of the greenhouse and the shading covers were left open. The expected flowering date was determined by checking records of the flowering dates for previous years and by continuously observing the condition of the tips of the female flowers of the cedar seedlings, and 12 days prior to that was set as the closure start date. The expected flowering date was set as February 1, 2023, and the closure start date was set as January 20, 2023. The openings on the exterior walls of the greenhouse were closed completely on the closure start date. Because closing the openings caused the temperature inside the greenhouse to rise and exceed 35°C, the exterior walls of the greenhouse were covered with a light-blocking cover from February 4, 2023, to block light from entering the greenhouse. Flowering was confirmed on February 5, 2023, and from that day onward, pollen was collected by suction from the male flowers every day. The pollen from nine seedlings was then purified by shaking it in a sieve and sprayed onto the female flowers of the nine seedlings using a pollen gun for artificial cross-pollination. On March 25, 2023, micropyle fluid secretion from the female flowers was no longer observed. On March 28, 2023, the light-blocking cover was rolled up to remove the light barrier, and the exterior wall opening was opened. The average maximum temperature inside the greenhouse from February to March 2023 was 25°C.

[0067] Growth continued thereafter, and on October 30, 2023, the dead seedlings were counted and the mortality rate was calculated. The total mass of the seeds grown up to that point was also weighed.

[0068] (Comparative Example 1) Except for the following changes, the same procedures as in Example 1 were carried out to grow cedar seedlings, and the mortality rate and total seed mass were evaluated. The method of applying the shading cover was changed to a form in which a sheet was placed along the inside of the exterior wall of the greenhouse, blocking light from reaching the cedar seedlings inside the exterior wall of the greenhouse.

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

[0070] (Examples 1 to 8 and Comparative Examples 2 to 4) Except for the following changes, the same procedures as in Example 9 were carried out to grow cedar seedlings, and the mortality rate and total seed mass were evaluated. - No light blocking was performed with a light-blocking cover after the closure start date in February to March 2023 (Comparative Examples 2 and 4). - From June to October 2022, on days when temperatures rose, no light was blocked by a shading cover (Comparative Examples 3 and 4). The number of irrigation times per day from May to October was set to one, and the irrigation amount per day was set to one time per day (Examples 1, 4 and 5 and Comparative Example 4). No insect net was used (Examples 1 to 2 and 5 to 6 and Comparative Example 4). Insecticide was sprayed only once in June, and no spraying was performed in August (Example 7). Insecticide was sprayed only once in August, and no spraying was performed in June (Example 8). No insecticide was sprayed (Examples 1 to 4 and Comparative Example 4).

[0071] Example 18 Except for the following changes, the same procedures as in Example 9 were carried out to grow cypress seedlings, and the mortality rate and total seed mass were evaluated. Instead of cedar seedlings, cypress seedlings (80 cm tall) were used. Regarding gibberellin administration, Sumitomo Gibberellin Paste (Sumitomo Chemical Co., Ltd., Ministry of Agriculture, Forestry and Fisheries Registration No. 24248) was administered once during the same period as the gibberellin administration period in Example 9, instead of spraying gibberellin powder. Administration was performed by peeling the bark from the base of each individual branch, injecting the paste, and then wrapping and securing it with grafting tape. By checking records of the flowering dates for previous years and continuously observing the condition of the tips of the female flowers of the cypress seedlings, the expected flowering date was set, with 8 days prior to that as the start date for closure. The expected flowering date was set as March 5, 2023, and the start date for closure as February 25, 2023. The shading cover was also closed from February 25th. Flowering was confirmed on March 10, 2023. On April 20, 2023, micropyle fluid secretion from the female flowers was no longer observed. On April 25, 2023, the shading cover was rolled up to remove the light shielding, and the exterior wall opening was opened. The average maximum temperature inside the greenhouse from February to April 2023 was 25°C.

[0072] (Comparative Example 5) Except for the following changes, the same procedures as in Example 18 were carried out to grow cypress seedlings, and the mortality rate and total seed mass were evaluated. The method of applying the shading cover was changed to a form in which a sheet was placed along the inside of the outer wall of the greenhouse, blocking light from reaching the cypress seedlings inside the outer wall of the greenhouse.

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

[0074] (Examples 10 to 17 and Comparative Examples 6 to 8) Except for the following changes, the same procedures as in Example 18 were carried out to grow cedar seedlings, and the mortality rate and total seed mass were evaluated. - No light blocking was performed with a light-blocking cover after the closure start date in February to March 2023 (Comparative Examples 6 and 8). - From June to October 2022, on days when temperatures rose, no light was blocked by a shading cover (Comparative Examples 7 and 8). The number of irrigations per day from May to October was set to one, and the amount of irrigation per day was set to one per day (Examples 10, 13 and 14 and Comparative Example 8). No insect net was used (Examples 10 to 11 and 14 to 15 and Comparative Example 8). Insecticide was sprayed only once in June, and no spraying was performed in August (Example 16). Insecticide was sprayed only once in August, and no spraying was performed in June (Example 17). No insecticide was sprayed (Examples 10 to 13 and Comparative Example 8).

[0075] The outlines and results of the Examples and Comparative Examples are shown in Tables 1 to 4. In Tables 1 to 4, the seed mass for the examples of cedar seedlings (Examples 1 to 9 and Comparative Examples 1 to 4) is shown as a relative value with Example 9 set to 100%, and for the examples of cypress seedlings (Examples 10 to 18 and Comparative Examples 5 to 8), it is shown as a relative value with Example 18 set to 100%. "Average maximum temperature inside the greenhouse from February to March or from February to April" indicates the values ​​for February to March for the examples of cedar seedlings and for February to April for the examples of cypress seedlings.

[0076] [Table 1]

[0077] [Table 2]

[0078] [Table 3]

[0079] [Table 4]

[0080] As is clear from the above results, when the cultivation method of the present invention, which involves specific opening treatment, temperature adjustment treatment, and temperature rise suppression treatment, is carried out, 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 growing forest seedlings in a facility's cultivation space, comprising: The facility is a facility with a ridge height of 4 to 5 m, in which the forest seedlings are surrounded by an exterior wall made of a light-transmitting covering material with a total light transmittance of 75% or more, and the exterior wall has an opening that can be opened and closed, and an openable and closable light-shielding cover that is hung on the exterior wall, The growing method comprises: an opening treatment in which the closing start date is set to be 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 closing start date; A temperature adjustment process for closing the opening to block foreign pollen and heating the facility during a closure period from the closure start date to the end of the flowering period; and a temperature rise suppression process in which the light-shielding cover blocks light from reaching the inside of the facility; Including, The end date of the flowering period is a date after the date on which it is confirmed that the secretion of micropyle fluid from the female flower of the forest seedling has ended, The shielding in the temperature rise suppression treatment is performed on days when the maximum daily temperature in the facility exceeds 35°C throughout the entire period in which the forest seedlings are grown in the facility. How to grow forest seedlings.

2. 2. The method for cultivating forest seedlings according to claim 1, further comprising watering the seedlings at least twice a day during the period from May to October during which the seedlings are cultivated.

3. 2. The method for growing forest seedlings according to claim 1, wherein the facility is provided with an insect net stretched over the opening.

4. 2. 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 from May to August during the period in which the forest seedlings are cultivated.

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

6. 2. The method for growing forest seedlings according to claim 1, wherein the shading rate of the shading cover is 30% or more.

7. 2. The method for cultivating forest seedlings according to claim 1, further comprising the steps of: causing the forest seedlings to flower during the period in which the forest seedlings are cultivated; and performing an artificial cross-pollination treatment after the flowering has begun.

8. A method for producing seeds of mountain forest seedlings, comprising cultivating the mountain forest seedlings by the method for cultivating mountain forest seedlings according to any one of claims 1 to 7, and harvesting seeds from the mountain forest seedlings.

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