Method for producing thallus of laver

Abstract

[Problem] To provide a method for producing a young leaf of laver and a method for land-based aquaculture of laver which utilize the advantages of land-based aquaculture and which are highly productive and innovative. [Solution] A method for producing a thallus of laver according to the present invention comprises at least the following steps in order. (1) A spore adhesion step for adhering conchospores released from a strand or monospores released from a thallus to an adhesion substrate at a surface density of 20-8,000 spores / mm2 <sp / >; (2) a spore germination step for germinating the conchospores or the monospores that have adhered to the adhesion substrate; and (3) a young leaf acquisition step for stripping, from the adhesion substrate, a thallus (young leaf) that has grown after the spore germination step and that has a length of 0.1-30 mm.

Description

Method for producing the thallus of Porphyra japonica

[0001] The present invention relates to a method for producing the thallus of Porphyra.

[0002] Porphyra and Pyropia species are widely known as edible seaweed and are extensively cultivated in East Asia, including Japan. In particular, pole cultivation is widespread in Japan and is considered one of the main production methods for cultivated seaweed. Pole cultivation is carried out by setting up poles at regular intervals in relatively shallow sea areas and stretching seaweed nets between these poles. In this method, the seaweed nets are moderately exposed above the water surface by the ebb and flow of the tides, promoting photosynthesis, and the risk of disease is reduced by exposure to sunlight. For this reason, it is widely used as a cultivation method that allows for stable production over many years (Non-Patent Literature 1).

[0003] The genus Porphyra is known to have a life cycle in which alternation of generations occurs between the thallus (gametophyte) and the filamentous sporophyte. This life cycle has an ingenious mechanism that allows for adaptive growth under different environmental conditions and the transmission of life to the next generation. Non-patent document 2 contains a diagram illustrating this life cycle of Porphyra, visually explaining its complex ecology. The thallus, which grows in winter, matures and forms carpospores through fertilization. The formed carpospores are released into the sea, attach to the surface of the shell, and then grow into filamentous spores by burrowing into the shell. The filamentous spores survive in the sea for a long period and form conchospores in the autumn. These conchospores grow into new thallus through meiosis, and the thallus forms carpospores again the following winter, thus completing alternation of generations. In addition to carpospore formation through sexual reproduction, the thallus can also form monospores. After germination, monospores grow directly into thallus without going through the filamentous stage and reproduce asexually (patent document 1). Therefore, when environmental conditions are suitable, the proliferation of clonal individuals by monospores is promoted, and the growth range can be rapidly expanded. It is this thallus that is used for food and has been utilized as an important marine resource since ancient times. In pole-type cultivation, conchospores or monospores released in the aforementioned life cycle are attached to seaweed nets, and seaweed is cultivated by growing the thallus in the sea.

[0004] Traditionally, aquaculture has been conducted at sea, but in recent years, interest in land-based aquaculture has been growing due to changes in the marine environment and the increasing risk of disease. However, many challenges remain in land-based aquaculture, such as optimizing the growth environment and establishing stable production techniques, and trial and error continues. Non-patent document 3 describes an example of such land-based aquaculture attempts, in which a cultivation method using kite string is being considered. In this document, a wave-making device that circulates seawater on land is used to recreate the environment of the shoreline, and in this environment, an attempt is made to get seaweed to attach and grow using kite string as a substrate. Non-patent document 4 presents an index for the appropriate attachment density for improving the quality and optimizing the yield of cultivated seaweed, showing that overcrowding inhibits the development of the base of the thallus.

[0005] Kawamura, Yoshio, "Basic Manual for Nori Production using the Pole-Support System," Saiyu Fisheries Research Report 18 (37-52), 1998. Nori Health Promotion Committee, "How Nori is Made," https: / / www.nori-japan.com / lecture / process / . Honma, Nobuyoshi, "Development of Equipment for Land-Based Nori Cultivation," Yamagata Prefecture Industrial Education "Special Research" Report, FY2023, https: / / www.pweb.jp / data / datayamagatasanshin / yamagatasanshinjy1134.pdf. Fushiya, Mitsuru, "Effect of Attachment Density on the Development of the Thallus Base of Cultivated Nori," Aichi Fisheries Research Institute Report No. 1 (1993), 59-62, https: / / www.pref.aichi.jp / uploaded / attachment / 6775.pdf

[0006] Japanese Patent Publication No. 2024-123678

[0007] Non-patent document 3 describes a land-based aquaculture technology that uses octopus string as a substrate for attaching seaweed, attempting to promote the growth of thallus in a land-based aquaculture environment. However, in this cultivation method, the attached conchospores are allowed to grow on the substrate until they become mature leaves, so there is little difference from conventional sea-based aquaculture other than the location of cultivation, and there is room for improvement in terms of efficiency. Furthermore, land-based aquaculture is a technology that is expected to enable planned and high-density production by taking advantage of the ability to control the environment. However, in terms of production efficiency, this cultivation method, in which the seaweed remains attached to octopus string, is not much different from conventional sea-based aquaculture using seaweed nets. Since it takes a certain period of time for the thallus to grow into mature leaves on the octopus string, it is not easy to shorten the production cycle, and further consideration is needed to realize a stable supply throughout the year.

[0008] The present invention's method for producing the thallus of Porphyra includes at least the following steps in order: (1) Conchospores released from the filamentous thallus or monospores released from the thallus are placed on a substrate at a surface density of 20 spores / mm². ２ ~8000 pieces / mm ２ (1) A spore attachment step in which spores are attached to the substrate; (2) A spore germination step in which conchospores or monospores attached to the substrate are germinated; (3) A juvenile leaf acquisition step in which thalli (juvenile leaves) that have grown after the spore germination step and are 0.1 mm to 30 mm in length are peeled off from the substrate.

[0009] In the production method of young leaves of Porphyra japonica and the land-based cultivation method of Porphyra japonica, it is possible to provide a highly productive method that takes advantage of the benefits of land-based cultivation.

[0010] Actual photograph of a thallus releasing a single spore Actual photograph of a substrate (glass plate) on which spores are attached Actual photograph of a substrate (glass plate) on which spores are attached Photograph of a substrate (glass plate) with spores attached in a beaker Photograph of a substrate (glass plate) with spores attached in a container Photograph of a thallus (young leaf) sprouting on the substrate Actual photograph of a thallus (young leaf) detached from the substrate Photograph of a thallus (young leaf) detached from the substrate Photograph of a thallus (young leaf) detached from the substrate being grown in an aquarium Photograph of a thallus detached from the substrate being grown in a pond-type aquarium (circular aquarium) Photograph of a thallus detached from the substrate being grown in a raceway-type aquarium Photograph of a frozen thallus Photograph of a filter used to separate thallus

[0011] 20 spores 30 thallus, solitary thallus or aggregated thallus

[0012] Hereinafter, several embodiments of the present invention will be described in detail with reference to the drawings. The designs described in the embodiments of the present invention can be modified as appropriate without altering the scope of the present invention.

[0013] <Description of Embodiments of the Invention> Embodiments of the present invention regarding the method for producing young leaves of Porphyra and the method for land-based cultivation of Porphyra will be described below with reference to the drawings. (About Porphyra) The Porphyra of the present invention refers to seaweed belonging to the genus Porphyra. There are various species in the genus Porphyra, each with different characteristics and uses. Representative examples include Susabinori, Asakusanori, Kaigaramanori, and Kuronori. Susabinori (Porphyra yezoensis) is the main species used in nori cultivation in Japan and accounts for the majority of market distribution. It grows quickly and is resistant to diseases. It is widely used as a raw material for roasted nori and seasoned nori. Asakusanori (Porphyra tenera) is treated as a high-grade nori due to its good flavor. Porphyra suborbiculata has a unique life cycle in which thallus forms directly from filamentous structures. It grows in tidal flats and rocky areas. Wild specimens are often treated as regional specialties. Porphyra dentata is distributed in warm regions such as Okinawa and Kyushu and is used in soups and preserved foods. In addition, Porphyra umbilicalis and Porphyra dioica are used as food in Europe, and Porphyra vietnamensis is used in Southeast Asia.

[0014] (1) Spore attachment process <Conchospores of Porphyra and their production method> Conchospores of Porphyra are reproductive cells formed by the sporophyte (filamentous body) in the life cycle of Porphyra, and play a role in growing into new thalli through meiosis. Conchospores develop within the shell to which the filamentous body is attached, and are released when specific environmental conditions are met. These conchospores attach to a suitable substrate and grow into thalli by germinating. In land-based aquaculture, it is possible to control the formation and release of conchospores by controlling the environment indoors. Specifically, conchospore production is promoted by adjusting water temperature, light irradiation, and nutritional conditions to provide appropriate stimulation to the filamentous body. For example, a method is used to induce conchospore release by maintaining a low temperature environment for a certain period and then raising the temperature, or by changing the photoperiod (Non-patent Literature 1). The released conchospores attach to substrates such as glass plates, filaments (synthetic fibers or nylon threads), mesh-like sheets, plastic plates, and porous substrates mainly composed of calcium carbonate, and germinate to grow into young leaves of the thallus. In land-based aquaculture, the selection and arrangement of these substrates and the optimization of the culture environment are crucial. With proper management, the timing of conchospore release can be systematically controlled, enabling efficient seedling supply. This allows for stable nori cultivation regardless of the season, contributing to stable production throughout the year.

[0015] <Monospores of Porphyra and their Production Method> Monospores of Porphyra are reproductive cells asexually formed by the thallus and have the characteristic of growing directly into new thalluses after germination. Unlike conchospores, monospores grow directly into thalluses without going through filamentous stages, allowing for rapid proliferation. By utilizing this characteristic, it is expected that production efficiency in land-based aquaculture will be improved. In land-based aquaculture, it is possible to control the release of monospores by controlling the environment and to supply seedlings in a planned manner. Specifically, monospore formation in thalluses is promoted by appropriately adjusting water temperature, photoperiod, and nutritional conditions, and then released into the culture tank. It is important to apply specific environmental changes to promote the release of monospores, and it is known that the maturity of the thallus and the composition of the culture medium have an effect. The released monospores attach to substrates such as glass plates, filaments (synthetic fibers or nylon threads), mesh-like sheets, plastic plates, and porous substrates mainly composed of calcium carbonate, and grow into thalluses (young leaves) after germination. These substrates affect the attachment efficiency and growth rate of monospores, making it crucial to optimize the substrate type and surface treatment. Furthermore, because monospores are released in large quantities at once, proper substrate placement and high-density attachment can lead to increased yields. Land-based cultivation utilizing monospores allows for the propagation of thallus without the need for filamentous structures, thus shortening the production cycle and making it a suitable method for planned nori supply. Figure 1 shows a photograph of monospores being released from thallus and attached to a substrate. In this invention, "spore" refers collectively to both "conchospores" and "monospores" as described above.

[0016] <Control of attachment density> This invention controls the surface density of conchospores released from filamentous bodies or monospores released from thallus bodies on the attachment substrate to a density of 20 spores / mm². ２ ~8000 pieces / mm ２The process involves a spore attachment step. In water (seawater), conchospores released from filamentous bodies and monospores released from thallus bodies attach to the substrate due to substrate affinity and adhesiveness. Therefore, the attachment density can be controlled by adjusting the number of spores generated in the tank and the amount of substrate. Furthermore, the attachment density can also be controlled by adjusting the time that the spores float and disperse. When attaching spores to a substrate on a flat surface such as a glass plate, the surface density of spores attached to the substrate can be determined by calculating the number of spores attached per unit area of ​​that plane. When using a substrate such as a filament, the surface density of spores attached to the substrate can be determined by calculating the number of spores attached per unit surface area of ​​the filament. For example, if the diameter of the filament is R and the length is L, the surface area of ​​the filament is defined as 2RπL. Figure 2a is an actual photograph of a substrate (glass plate) on which spores are attached. The symbol 20 in the figure represents one spore. This photograph shows a magnified view under a microscope of an area measuring 0.464 mm x 0.629 mm. Since 193 spores are attached to this area, the spore density on this substrate is 661 spores / mm². ２ This indicates that the spores are attached to the substrate. Figure 2b is an actual photograph of a substrate (glass plate) on which spores are attached, taken during another experiment. In the photograph, 53 spores are attached to a substrate measuring 0.074 mm × 0.093 mm, so this substrate has a spore density of 7701 spores / mm³. ２ This means they are attached to the surface. When attached as densely as possible, the surface density is 8000 plants / mm². ２ That is the case.

[0017] In this invention, young leaves germinated from spores are detached from the substrate while still young, without being grown to mature leaves, and then grown to mature leaves while floating in a tank. This method shortens the growth period on the substrate and improves the turnover rate of the attachment surface. As a result, it becomes possible to increase the attachment surface density on the substrate surface, dramatically improving the productivity of land-based cultivation of Porphyra. In this invention, conchospores released from filamentous bodies or monospores released from thallus are attached to the substrate at a surface density of 5 spores / mm². ２ ~8000 pieces / mm２ or 20 pieces / mm ２ to 8000 pieces / mm ２ to be attached. In particular, it is desirable to attach spores at an areal density of 50 pieces / mm ２ or more, and as a more preferable range of areal density, 100 pieces / mm ２ or more, more preferably 200 pieces / mm ２ or more, further 300 pieces / mm ２ or more, 400 pieces / mm ２ or more, 500 pieces / mm ２ or more is recommended. The agglomerated thalli (thallus group) have the advantage that a plurality of thalli are intertwined to form a mass, thereby having a certain buoyancy and being easy to float appropriately in the water tank. On the other hand, if agglomeration proceeds excessively, the close contact between the thalli becomes stronger, which may make it difficult to separate and handle individual thalli. In particular, in cases where it is desired to grow thalli individually, or in situations where uniformity of distribution in the water tank is emphasized, excessive agglomeration can be an obstacle to management. Therefore, it is desirable to appropriately adjust parameters such as the attachment density according to the intended use of the thalli and the aquaculture conditions to control the degree of agglomeration. In the present invention, it is desirable that the producer can freely adjust the attachment density according to the shape of the thallus and the aquaculture form that the producer ultimately wants to obtain. For example, when it is desired to grow the thalli as individually as possible, the attachment density is set to a relatively low level (for example, 3000 pieces / mm ２ or less, more preferably 2000 pieces / mm ２By setting the following parameters, the occurrence of clumping can be further suppressed. Furthermore, the reason for setting an upper limit on the attachment density is explained below. When young leaves are attached in an overcrowded state, it becomes difficult not only to detach them from the attachment substrate, but also to uniformly disperse them in the tank after detachment. In particular, the young leaves of Porphyra japonica (Porphyra japonica) have a single-layer, thin, membranous structure, and their intercellular adhesion is weak, resulting in low physical strength, making them unsuitable for division or crushing by mechanical means (e.g., mixers). Therefore, if an excessively high-density attachment state is attempted to be processed as is, the thallus may be destroyed, potentially leading to poor growth and reduced quality in subsequent floating culture processes. In contrast, Ulva genus (Ulva) has a multilayered or tubular structure in its thallus, and its intercellular adhesion is strong, so the structure of the thallus is easily maintained even by mechanical processing, making it suitable for dispersion processing from a high-density state. In other words, while high attachment surface density in Aonori (a type of seaweed) does not pose significant processing problems, the structural fragility of Chronori (another type of seaweed) makes appropriate surface density management essential. Therefore, in order to efficiently detach and collect the young leaves from the substrate with minimal damage, while considering the structural characteristics of the young leaves, it is important to control the attachment surface density to below an appropriate upper limit.

[0018] (2) Spore germination process <Attachment and growth of conchospores and monospores> After attaching to the attachment substrate, conchospores and monospores are grown in seawater for a certain period until they germinate and grow into young leaves. In this invention, cultivation from young leaves to mature leaves is assumed to be land-based cultivation using large tanks. Therefore, it is assumed that the thallus will detach from the attachment substrate at the young leaf stage when it is still small, and the growth period on the attachment substrate is characterized by being short. Figure 3a shows an actual photograph of an attachment substrate (glass plate) with spores attached being grown in seawater in a beaker. Figure 3b shows a state in which graph paper with 1 mm divisions is placed on the back of a transparent container to make the size of the spores attached to the attachment substrate easier to see.

[0019] (3) Step for acquiring young leaves In the step for acquiring young leaves of the present invention, once the spores have germinated, sprouted, and grown to a certain extent on the substrate, they are detached from the substrate as young leaves without being allowed to grow to mature leaves. Specifically, thalli (young leaves) with a length of 0.03 mm to 30 mm or 0.1 mm to 30 mm that have grown after spore germination are peeled off from the substrate. In other words, the peeled thalli are thalli that are not attached to the substrate. When peeling off sprouted thalli (young leaves), the peeled part may be damaged, so it is desirable to peel off the thalli after it has grown to a certain extent. In particular, it is desirable that the length be 0.03 mm or more, preferably 0.1 mm or more, and even more preferably 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, and 1 mm or more. Furthermore, in this invention, since the thallus is grown at high density on the substrate, excessive growth of the thallus may disrupt the growing environment. Therefore, it is desirable to detach the thallus from the substrate when its length is 30 mm or less. It is also desirable to detach the thallus from the substrate within one month after the spores attach to the substrate. This suppresses excessive growth of the thallus, enabling stable acquisition of young leaves while maintaining a high-density growing environment. In this invention, the entire process from spore attachment to detachment of the thallus is carried out in a land environment, not at sea. Figure 3c is an actual micrograph showing the state in which the spores have germinated and sprouted on the substrate. In this example, it was observed at a magnification of approximately 400x. Figure 3c includes a scale acquired simultaneously with the imaging, and when measured using this scale as a reference, the sprouted thallus observed in the figure had a length of approximately 30 mm to 60 mm in the image. Therefore, it can be seen that the actual size is approximately 0.075 mm to 0.15 mm. Figure 4a shows an actual photograph of a thallus (young leaf) immediately after detachment from the substrate. By individually detaching the thallus from the substrate after sprouting, clumping of thallus can be suppressed. In other words, it is desirable to detach one thallus in a way that prevents it from becoming entangled with other thallus.Unlike seaweed such as green laver, the thallus of *Crocidolomia spp.* is delicate, making it difficult to mechanically subdivide the aggregate of young leaves using a mixer or similar device. Therefore, it is important to individually separate and collect the thallus during the detachment stage from the substrate. On the other hand, Figure 4b shows a state where multiple thallus are tightly attached at their tips and have aggregated. By greatly increasing the density of attachment on the substrate, when the young leaves are detached from the substrate, they can intertwine with each other and form aggregated thallus at a certain rate.

[0020] Both Pyropia (genus Porphyra) and Ulva (genus Lagombi) can be cultivated in aquariums, but their appropriate cultivation processes differ due to differences in morphological characteristics at the germination stage and their ability to adhere to the substrate. Ulva has relatively weak adhesion to the substrate before germination, and its adhesive strength remains low even as the thallus grows. Therefore, in aquarium cultivation, it is suitable to detach it from the substrate before germination and sow it in the aquarium. This makes it easier to manage attached organisms and allows for the formation of uniform thallus. On the other hand, Porphyra has extremely high adhesion to the substrate in the conchocelis-phase (filamentous stage) before germination or in the minute thallus immediately after germination. In particular, the filamentous stage before germination tends to adhere strongly to the walls and pipes in the aquarium, which is likely to be an obstacle to cultivation management. Therefore, in cultivating Pyropia, it is desirable to germinate the thallus on a substrate, and once it has grown to a certain size, detach it from the substrate and transfer it to a tank for cultivation. This avoids excessive attachment and improves cultivation efficiency and quality stability. The pre-germination (concopoly phase) and post-germination (thallus) stages of Pyropia (genus Porphyra) can be distinguished by the following morphological characteristics under a microscope: ・Pre-germination (concopoly phase): Exhibits an elongated filamentous structure consisting of cells arranged in a single row. It is pale pink in color and grows in a branching manner along the substrate. Its thickness is approximately 10-20 μm. ・Post-germination (thallus): Exhibits a thin, flattened membranous structure, and the cells are broadly reddish-purple. The thallus is initially less than 1 mm, but expands with growth. After collection, the sample is washed with physiological saline solution, stained as necessary, and identified by observation under a light microscope (200-400x magnification).

[0021] (4) Diagram 5 of the process in the small tank after detachment shows an actual photograph of the thallus (young leaves) being grown in a tank after being detached from the substrate. It is desirable to grow the thallus (young leaves) detached from the substrate in a small tank for a certain period of time. Immediately after detachment, the thallus has the property of trying to attach to surfaces such as the sides of the tank due to its substrate affinity and epiphytic properties. If the tank is large, the distribution of thallus attached to the sides will be widespread, making the removal work complicated and reducing management efficiency. For this reason, it is suitable to grow the thallus in a small tank until it has grown sufficiently and can float or drift stably. In particular, when the young leaves detached from the substrate are 50 mm or less in length, it is desirable to grow them in a tank with a water volume of 2 tons or less. Note that this small tank cultivation process is not mandatory and can be omitted. The thallus detached from the substrate can be immediately placed in the large tank described below and cultivation can begin. For example, thalli detached from a substrate can be grown by sequentially transferring them to multiple tanks according to their growth stage. As an example, thalli immediately after detachment can be grown in a small tank of about 1 liter, then moved to a large tank of about 100 liters once they have grown to a certain extent, and finally transferred to a tank of about 10 tons for further growth. More generally, it is desirable to use small tanks with a capacity of 1 to 50 liters as the first stage, medium-sized tanks with a capacity of 50 to 200 liters as the second stage, and tanks with a capacity of 0.2 to 20 tons as the third stage, switching tanks in stages according to the growth stage of the thalli. By changing the tank capacity in stages in this way, it is possible to achieve both manageability immediately after detachment and subsequent large-scale cultivation, thereby improving the efficiency of the entire aquaculture process.

[0022] (5) Floating Cultivation Process In the method for producing the thallus of Porphyra according to the present invention, it is desirable to cultivate the thallus (young leaves) that have been detached from the epiphytic substrate while floating in a large tank (for example, a tank with a water volume of 5 tons or more) and being agitated by the water flow. As a large tank, a water flow circulation type tank, that is, a tank that circulates water horizontally in a plan view, is suitable. Examples of water flow circulation type tanks include pond-type tanks and raceway-type tanks, but other tanks with similar functions may be used. A pond-type tank (circular tank) is equipped with a stirrer near the center that agitates the water flow in the circumferential direction. On the other hand, a raceway-type tank has a structure in which the water flow flows in a race track shape, and the water flow is circulated by a water wheel installed in the track. These tanks are suitable for cultivating the young leaves of Porphyra that have been detached from the epiphytic substrate until they become mature leaves. Figure 6a shows a photograph of thallus that have been detached from the epiphytic substrate being cultivated in a pond-type tank (circular tank). The image shows numerous thallus bodies floating and being agitated in the tank as they are being cultivated. Figure 6b is a photograph of thallus bodies that have detached from the substrate being cultivated in a raceway-type tank. Since Porphyra has particularly strong adhesive properties among seaweeds, it is desirable to use a water circulation type tank that is less prone to stagnation in order to suppress the attachment of thallus bodies to the inner walls of the tank container. When using a raceway-type tank or a pond-type tank, it is desirable to provide a circulating water flow that does not damage the thallus bodies while suppressing their attachment to the tank container walls. The lower limit of the water flow will be explained. The average flow velocity in the tank should preferably be at least 0.01 m / s, preferably 0.02 m / s, and more preferably 0.03 m / s. If the average flow velocity is less than 0.01 m / s, stagnation is likely to occur in the tank, and there is a risk that the thallus bodies will sink and attach to the bottom or walls. The upper limit of the water flow will be explained. The average flow velocity in the tank should preferably be 5 m / s or less, and more preferably 3 m / s or less. If the average flow velocity is excessively high, collisions between thalli and shear forces due to water flow will increase, which may damage the thalli.

[0023] (6) Freezing Process It is also desirable to freeze the thallus (young leaves) obtained in the young leaf acquisition process and the thallus cultivated in the floating cultivation process. In other words, it is also desirable to freeze the thallus detached from the attachment substrate and the thallus for floating cultivation in land-based aquaculture. In particular, freezing thallus that are not large enough to be shipped as Amanori and distributing them to other producers can be expected to further improve production efficiency. Producers who receive frozen thallus for floating cultivation can thaw them, put them into their large tanks, cultivate them to mature leaves, and ship them. This eliminates the need for producers to manage the initial stages of cultivation, such as Amanori spores, and allows them to concentrate on cultivating young leaves to mature leaves in large tanks. In this way, by utilizing the freezing and distribution of thallus, a stable supply of aquaculture becomes possible and the expansion of the production system is promoted. In conventional aquaculture technology using seaweed nets, freezing the seaweed nets themselves is a well-known technique. However, the method of freezing and utilizing thallus detached from the substrate, as described in this invention, is a groundbreaking approach and will lead to the establishment of a new production method. In this freezing process, the minimum size (length) of the thallus to be frozen is preferably 0.1 mm or more, and more preferably 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, or 1 mm or more. It is also possible to freeze thallus to a size (length) of 20 mm or more, 30 mm or more, 40 mm or more, or 50 mm or more. The larger the size of the thallus, the easier it is to cultivate it in a tank after thawing. For example, when cultivating frozen thallus in a large tank after thawing, if the thallus is small, it is necessary to prepare multiple tanks according to the size during the process of growing it to a mature leaf. However, if the thallus to be frozen is large, the size restrictions of the tanks required for cultivation after thawing are relaxed, which has the advantage of simplifying management. The upper limit for the size of the thallus to be frozen is preferably 20 cm or less, assuming that it is a thallus that will not be shipped. Furthermore, it is more preferable that it be 15 cm or less, and most preferably 10 cm or less.

[0024] When freezing thalli of a species that are not large enough for shipment, it is desirable to freeze them in two or more groups of different sizes. For example, one group could contain thalli with an average size of about 0.5 mm, and the other group could contain thalli with an average size of about 20 mm. By freezing these groups separately, it is possible to meet the needs of producers who require thalli of different sizes. Furthermore, it is even more desirable to freeze them in groups of three or more sizes. For example, by classifying them into three groups of about 0.5 mm, 10 mm, and 20 mm, it is possible to supply thalli suitable for different stages of the cultivation process. It is also desirable to classify them into four or more groups; for example, by freezing thalli of about 0.5 mm, 5 mm, 20 mm, and 50 mm, it is possible to meet an even wider range of production needs. In cultivation methods where thalli are detached from a substrate and grown in large tanks, there are more diverse options for the type of tank used and management methods for cultivating thalli compared to cultivation on the sea surface using seaweed nets. Therefore, as described above, when freezing thalli, various methods are possible, such as classifying and storing thalli of different sizes, or selecting a freezing method that takes into account growth after thawing. Furthermore, in this invention, it is also possible to freeze the thalli before detaching them from the substrate, that is, while the thalli are still attached to the substrate. In this case, after thawing, the thalli may be detached from the substrate and subjected to the floating growth process, or the substrate and thalli may be introduced into the growth process together. Thus, freezing of thalli is not limited to after detachment, but also includes methods performed while they are still attached to the substrate. Figure 7 shows an actual photograph of frozen thalli. Figure 8 is a photograph showing the state in which thalli have been separated using two filters of different sizes.

[0025] The following is an outline of the invention related to the technology described in the freezing process above. (A) A method for producing thalli of Porphyra, comprising at least the following steps in order: 1. A spore germination step in which conchospores or monospores attached to the substrate are germinated; 2. A young leaf acquisition step in which thalli (young leaves) with a length of 0.03 mm to 30 mm or 0.1 mm to 30 mm that have grown after the spore germination step are detached from the substrate; 3. A young leaf freezing step in which the young leaves acquired in the young leaf acquisition step are frozen. It is desirable that the thalli detached from the substrate have sprouted. It is also desirable that the detached thalli are not aggregated with other thalli. (B) A method for producing thalli of Porphyra, comprising at least the following steps in order: 1. A spore germination step in which conchospores or monospores attached to the substrate are germinated; 2. 1. A method for producing thalli of Porphyra, comprising at least the following steps in order: 1. A spore germination step in which conchospores or monospores attached to the substrate are germinated; 2. A step in which thalli (young leaves) grown after the spore germination step to a length of 0.03 mm to 30 mm or 0.1 mm to 30 mm are detached from the substrate; 3. A floating cultivation step in which the thalli (young leaves) obtained in the young leaf acquisition step are grown floating in a tank; 4. A young leaf freezing step in which the young leaves obtained in the floating cultivation step are frozen. It is desirable that the thalli detached from the substrate have sprouted. It is also desirable that the detached thalli are not aggregated with other thalli. (C) A method for producing thalli of Porphyra, comprising at least the following steps in order: 1. A spore germination step in which conchospores or monospores attached to the substrate are germinated; 2. A step in which thalli (young leaves) are grown to a length of 0.03 mm to 30 mm or 0.1 mm to 30 mm after the spore germination step; 3. (D) A young leaf freezing process in which young leaves grown on an epiphytic substrate are frozen, and it is desirable that the thallus grown on the epiphytic substrate has sprouted. Furthermore, it is desirable that the thallus that is subsequently detached is not clumped together with other thallus. (D) A method for producing thallus of Porphyra, which involves thawing frozen thallus for floating cultivation in land-based aquaculture (thallus that has been detached from an epiphytic substrate and subsequently frozen) and cultivating them in a tank. Various related variations of the above description can be adopted for each of these inventions A to D.

[0026] According to this embodiment, after germinating conchospores or monospores attached to the substrate, the sprouted thallus is detached from the substrate and frozen. This makes it possible to preserve and distribute the thallus itself as seedlings, unlike conventional cultivation techniques using seaweed nets. This allows advanced management processes such as spore management and initial cultivation to be concentrated in specific facilities, enabling each producer to concentrate on the process of introducing thawed thallus into tanks and cultivating them until they become mature leaves. Therefore, the present invention aims to stabilize the supply of seedlings and divide the production process in seaweed cultivation, thereby constructing a new production system that enables large-scale cultivation and labor saving.

[0027] (7) Examples of Variations of the Invention <Attachment Substrate> An example of an attachment substrate in the present invention is shown. Any substrate that can support the attachment of numerous spores is not limited to a specific material, and various types of substrates can be used. In the cultivation of Porphyra, conchospores released from the conchospore culture substrate attach to the attachment substrate, germinate and grow, and develop into thallus. This attachment substrate is required to have a structure that allows conchospores to attach and germinate efficiently and promotes the growth of thallus. Specific examples of attachment substrates include glass plates, filaments (synthetic fibers or nylon threads), mesh-like sheets, plastic plates, and porous substrates mainly composed of calcium carbonate. Glass plates can be used as attachment substrates. Appropriate roughening of the glass surface can promote the attachment of conchospores. In addition, glass is chemically stable, can withstand long-term use, and has the advantage of being easy to reuse as a substrate. Synthetic fibers such as nylon and polyester are suitable for filaments. The thin, filamentous structure is suitable for conchospore attachment and is less affected by water currents, resulting in uniform growth of the thallus. It is also highly durable and suitable for long-term cultivation. Mesh-like sheets and plastic plates are also suitable as attachment substrates. Mesh sheets allow water currents to pass through easily, and the distribution of conchospores tends to be uniform, resulting in stable growth of the thallus. Plastic plates can have their attachment rates improved by surface processing and can be processed into various shapes, allowing for design according to the application. Porous substrates mainly composed of calcium carbonate can also be used. Porous materials processed from coral or limestone provide an environment that facilitates conchospore attachment and promotes healthy growth of the thallus. Attachment substrates are called by various names, including cultivation substrate, attachment base, culture substrate, support material, growth substrate, attachment material, cultivation plate, and mesh material. In this invention, any form of epiphytic substrate can be used, regardless of its structure or designation, as long as it promotes the attachment and germination of conchospores and accelerates the growth of thallus. Cultivation environments for young leaves using epiphytic substrates include indoor culture facilities and outdoor aquariums, which are selected appropriately depending on the purpose and conditions. Furthermore, methods for supplying seawater include not only flow-through systems but also circulating systems and static culture systems.Proper management of water temperature, light exposure, and nutrient supply is crucial for promoting the growth of thallus.

[0028] <Water Circulation Tank> An example of a water circulation tank in the present invention is shown. In land-based cultivation of Porphyra, circular tanks (pond-type tanks) and raceway tanks are mainly used as tanks for introducing thallus that have already grown from conchospores. These tanks are designed to maintain the healthy growth of Porphyra and optimize the process until harvest, and the management of water flow and water quality is an important element. A pond-type tank (circular tank) (see Figure 6a) has a structure in which the water flow rotates in either the left or right direction by a stirrer installed in the center of the tank. This stirrer provides appropriate stirring within the tank, ensuring that sunlight is evenly irradiated to the entire thallus, and that the water flow is uniformly distributed, creating an environment in which nutrients are effectively supplied. Furthermore, the even water flow acting on the thallus is expected to promote its growth. The size and depth of the tank need to be appropriately adjusted according to the amount of thallus to be introduced and the scale of cultivation. In this invention, the diameter of the circular tank is preferably 5 m or more, more preferably 8 m or more, and even more preferably 10 m or more. The raceway tank (see Figure 6b) has a structure that circulates water in a racetrack-shaped rectangular tank, and the water flow that flows in a constant direction provides appropriate stimulation to the thallus. Due to the characteristics of this water flow, sunlight reaches the entire thallus evenly, promoting uniform growth and improving the efficiency of photosynthesis. In addition, by connecting multiple raceway tanks, it is possible to operate as a large-scale aquaculture facility, and the circulating water flow management has the advantage of stabilizing oxygen supply and nutrient distribution. The size and depth of the tank need to be appropriately adjusted according to the amount of thallus to be introduced and the scale of aquaculture. In this invention, the length of the raceway tank in the extension direction is preferably 20 m or more, and more preferably 40 m or more. The method for producing the thallus of Porphyra according to the present invention enables more efficient production of Porphyra compared to conventional methods, and its effects are particularly pronounced in cultivation environments using large tanks such as circular tanks (pond-type tanks) and raceway tanks.

[0029] While several embodiments of the present invention have been described, these are merely examples and are not intended to limit the scope of the invention. The present invention is not limited to the specific configurations and processes described, and various modifications, improvements, and applications are possible as long as they do not depart from the spirit and scope of the invention. For example, a wide variety of variations are possible depending on technical requirements and operating environments, such as the type and shape of the substrate for attachment, the setting of conditions for the aquaculture environment, and the devising of the freezing and preservation method. Furthermore, various omissions, substitutions, and modifications can be made without departing from the gist of the invention, and these modifications are also included within the scope of application of the present invention. In addition, the technical idea of ​​the present invention extends to the invention described in the claims and its equivalents.

Claims

1. A method for producing the thallus of Porphyra, comprising at least the following steps in order: (1) Arranging conchospores released from the filamentous thallus or monospores released from the thallus on a substrate at a surface density of 20 spores / mm². ２ ~8000 pieces / mm ２ (1) A spore attachment step in which spores are attached to the substrate; (2) A spore germination step in which conchospores or monospores attached to the substrate are germinated; (3) A juvenile leaf acquisition step in which thalli (juvenile leaves) that have grown after the spore germination step and are 0.1 mm to 30 mm in length are detached from the substrate.

2. In the spore attachment process described above, the surface density of conchospores or monospores attached to the attachment substrate is 5 spores / mm². ２ ~8000 pieces / mm ２ The method for producing thalli of Porphyra according to claim 1, wherein the step of obtaining young leaves is a step of peeling thalli (young leaves) with a length of 0.03 mm to 30 mm or less that have grown after the spore germination step from the attachment substrate.

3. The method for producing thallus of Porphyra according to claim 1 or 2, wherein the young leaf acquisition step includes a step of peeling off the thallus that has sprouted in the epiphytic substrate.

4. A method for producing thallus of Porphyra according to any one of claims 1 to 3, comprising a floating cultivation step of cultivating the thallus (young leaves) obtained in the young leaf acquisition step by floating them in a water tank.

5. A method for producing thallus of Porphyra according to any one of claims 1 to 4, comprising a floating cultivation step in which the thallus (young leaves) obtained in the young leaf acquisition step are grown by floating them in a water tank with a volume of 2 tons or less while their length is 50 mm or less.

6. A method for producing thallus of Porphyra according to any one of claims 1 to 5, comprising a floating cultivation step of cultivating the thallus (young leaves) obtained in the young leaf acquisition step by floating them in a water-circulating aquarium.

7. The method for producing the thallus of Porphyra according to claim 6, wherein the water circulation tank is a pond-type tank or a raceway-type tank.

8. A method for producing the thallus of Porphyra according to any one of claims 1 to 3, wherein the young leaves obtained in the young leaf acquisition step are frozen.

9. A method for producing thallus of Porphyra according to any one of claims 4 to 7, wherein the thallus cultivated in the floating cultivation step is frozen.

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