Cultivation method and seedling raising method of kale

Abstract

To provide a kale seedling suitable for hydroponic cultivation.SOLUTION: An embodiment of the present invention is a production method of a kale seedling for hydroponic cultivation, and includes a step of disseminating a plurality of kale seeds for each of a plurality of dissemination positions on a planar seedling-raising material.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a novel method for hydroponic cultivation of kale and a method for producing seedlings for hydroponic cultivation. [Background technology]

[0002] Kale is a plant of the Brassicaceae family that is said to have originated in the Mediterranean coast and is considered to be the original species of cabbage. Kale is generally rich in vitamins, iron, calcium, and other minerals, and has an excellent nutritional balance, so it is sometimes called the king of green and yellow vegetables.

[0003] For example, in the Designer Foods Pyramid published by the National Cancer Institute (NCI) in the United States in 1990, which represents vegetables that are effective in suppressing cancer, many Brassicaceae plants rank high (Non-Patent Document 1, etc.), and among Brassicaceae plants, kale is recognized as a green and yellow vegetable that is particularly highly rated for its functionality.

[0004] However, especially in Japan, kale remains a less familiar vegetable compared to cabbage and other vegetables. Kale's uses as a food ingredient are limited, and it is generally only recognized as an ingredient in stews and green juice, for example. Expanding the uses of kale as a food ingredient is considered to be one promising way to give a boost to the further spread of kale.

[0005] The present inventors, as one of the leading experts in the breeding of Brassicaceae plants, have developed various varieties of kale. For example, Samba Carnival (Japan Variety Registration No. 17704) developed by the present inventors maintains the excellent characteristics of kale while also having the characteristics of being less bitter and soft, and as an "edible kale" that can be eaten raw, it has made a significant contribution to expanding the uses of kale as a food ingredient.

[0006] Various studies have also been conducted on the possibility of cultivating kale at a so-called high density to expand the uses of kale as a food ingredient. For example, Patent Document 1 describes a method for cultivating kale seedlings at a predetermined interval and the kale obtained by harvesting. Patent Document 2 describes a method for cultivating kale seedlings at a predetermined interval in a light environment limited to a substantially closed plant factory. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent No. 6440879 [Patent Document 2] Patent No. 7195474 [Non-patent literature]

[0008] [Non-Patent Document 1] Caragay, AB: Cancer preventive foods and ingredients. Food Technol. 4 : 65-68, 1992 Summary of the Invention [Problem to be solved by the invention]

[0009] Hydroponic cultivation of kale has just begun, and there are many areas that require technical improvement. As mentioned above, kale is generally recognized only as an ingredient for stews and green juice, so there is a lot of room to contribute to expanding the uses of kale as an ingredient, not only through breeding approaches but also through improving its cultivation methods.

[0010] For example, neither Patent Document 1 nor Patent Document 2 provides any new knowledge regarding a method for producing (raising) seedlings for hydroponic cultivation. Therefore, the inventors of the present application reexamined the methods for producing and cultivating seedlings, assuming hydroponic cultivation, and conducted intensive research into the possibility of expanding the uses of kale as a food ingredient while improving its productivity.

[0011] One aspect of the present invention aims to provide a novel cultivation method for kale that can expand the uses of kale as a food ingredient and improve its productivity. Another aspect of the present invention aims to provide a method for producing kale seedlings for hydroponic cultivation that is suitable for this novel cultivation method. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides, for example, the following aspects. (1) A method for producing kale seedlings for hydroponic cultivation, comprising a step of sowing multiple seeds at each of a plurality of sowing positions on a planar seedling material. (2) The method for producing a plant according to (1), wherein 2, 3 or 4 seeds are sown in each of a plurality of sowing positions. (3) A manufacturing method described in (1) or (2), in which the planar seedling raising material is a urethane mat. (4) A method for hydroponically cultivating kale using a panel having a plurality of holes for planting seedlings, the method comprising a step of planting two, three or four kale seedlings in each of the holes. (5) The method according to (4), wherein two, three or four seedlings corresponding to each of the sowing positions produced by the production method according to any one of (1) to (3) above are planted. (6) A method according to (4) or (5) above, in the manufacturing method described in (2) or (3) above, wherein three seeds are sown in each of a plurality of sowing positions, and three kale seedlings are obtained per sowing position, and then planted in each of the holes. (7) A method according to any one of (4) to (6), wherein the spacing between the multiple holes in the panel for planting seedlings is greater than 5 cm and not greater than 25 cm. (8) The method according to any one of (4) to (7), comprising a harvesting step of harvesting the obtained kale by cutting. Effect of the Invention

[0013] According to one aspect of the present invention, it is possible to provide a novel cultivation method for kale that can expand the uses of kale as a food ingredient and improve the productivity of the same. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a diagram showing the germination state of seeds according to one embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the results of carrying out a cultivation method according to an embodiment of the present invention. [Diagram 3] FIG. 3 is a diagram showing the results of carrying out a cultivation method according to an embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the results of carrying out a cultivation method according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [1. Kale seedling production method] (An example of the method and its effects) A method for producing kale seedlings for hydroponic cultivation according to one embodiment of the present invention includes a step of sowing multiple kale seeds at each of a plurality of sowing positions on a planar seedling raising material. One of the objectives of the present invention is to provide kale in an easier-to-eat state by improving the manufacturing method and cultivation method of kale seedlings in hydroponic cultivation, to make kale a common vegetable that is eaten more regularly, and to contribute to the healthy lifespan of humanity (especially Japanese people) through this. Such an objective coincides with, for example, SDG 3. "Good health and well-being for all." Another objective of the present invention is to contribute to improving the productivity of such kale.

[0016] (Kale) In this specification, kale broadly refers to a plant classified as Brassica oleracea L var. acephala or Brassica oleracea L convar. acephala, or a plant having one of these plants as a parent. Specific varieties classified as kale include, for example, Brassica oleracea L. convar. acephala (DC) Alef. var. sabellica L., such as Juicy Green (Variety Registration No. 12578), Sweet Green (Variety Registration No. 17702), Samba Carnival (Variety Registration No. 17704), Kitchen (Red) (Unregistered), Kitchen (Green) (Variety Registration No. 17703), Gozilan (Carboro Leaf Green) (Variety Registration No. 17701), etc.; Mini Vert No. 8 (Variety Registration No. 20651) having Brassica oleracea L. convar. acephala (DC) Alef. var. sabellica L. as one parent; but are not limited to these. Among the varieties specifically exemplified, Samba Carnival is particularly preferred. In this specification, kale refers to edible kale, and therefore ornamental leaves, for example, are not included in the category of kale in this specification.

[0017] (seedling) As used herein, "kale seedlings or kale seedlings" refers to young kale plants that are grown for the purpose of being transplanted (i.e., planted) in the future.

[0018] The kale seedlings to be planted are not particularly limited, but are preferably seedlings in which the cotyledons have not yet unfolded and the main leaves have not yet fully unfolded, or seedlings in which one or more and eight or less main leaves have unfolded, more preferably seedlings in which the cotyledons have not yet unfolded and the main leaves have not yet fully unfolded, or seedlings in which one or more and four or less main leaves have unfolded, even more preferably seedlings in which the cotyledons have not yet unfolded and the main leaves have not yet fully unfolded, or seedlings in which one or more and three or less main leaves have unfolded, and particularly preferably seedlings in which the cotyledons have not yet unfolded and the main leaves have not yet fully unfolded, or seedlings in which one or more and two or less main leaves have unfolded.

[0019] (Seedling raising process) The method for growing (raising) kale seedlings is not particularly limited, but an example thereof includes a method in which kale seeds are sown on a surface-shaped seedling raising material, and after germination, the seeds are raised until they become plant bodies (seedlings) of a predetermined size suitable for planting.

[0020] The planar seedling raising material is not particularly limited as long as it is a water-permeable material having a planar (e.g., rectangular flat) spread, such as a urethane mat, a rock wool mat, or a sponge mat, but a urethane mat is preferred. The sowing process of kale seeds is carried out by sowing a plurality of seeds at each of a plurality of sowing positions on the planar seedling raising material. The plurality of sowing positions (sowing areas) on the seedling raising material refers to 1) the seedling raising material itself when the seedling raising material has a plurality of depressions for sowing (which may be cross-shaped cuts instead of depressions), and 2) the seedling raising material refers to a plurality of independent areas on the surface of the material when the seedling raising material is flat and does not have depressions for sowing. That is, in the case of 2), a plurality of independent sowing positions (sowing areas) are formed by sowing seeds in an island shape on the surface of the seedling raising material.

[0021] The number of seeds sown in the sowing position (seeding area) is more than one, preferably 2, 3, or 4, more preferably 3 or 4. By sowing multiple seeds in the same sowing position, the 100% germination rate of each sowing position increases. The 100% germination rate of each sowing position refers to the probability when the "number of all sowing positions sown" is the denominator and the "number of sowing positions where all the sowed seeds have germinated" is the numerator. In the range where the number of seeds sown in the sowing position (seeding area) is 1 to 5 or more, the 100% germination rate of each sowing position tends to increase as the number of seeds sown increases, and when 5 seeds are sown, it can be almost 100%. In addition, the 100% germination rate of each sowing position shows a very clear difference between when the number of seeds sown is 1 and when the number of seeds sown is 2. In addition, the tendency for the 100% germination rate at each sowing position to increase as the number of seeds sown increases is particularly evident when the seedling raising material is flat and does not have any depressions for sowing. In particular, it is preferable to sow the same number of seeds in each of 25% or more (preferably 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or all) of the sowing positions on the planar seedling raising material. By increasing the 100% germination rate of each sowing position, it becomes easier to form the same number of seedlings in each sowing position. In addition, it is preferable that the number of seeds sown in the sowing position (sowing area) is 2, 3, or 4, and 3 or 4 is more preferable, because these have a high germination rate of 100% and can be used as is when planting 2, 3, or 4 seedlings in holes in a hydroponic cultivation panel, as described below.

[0022] The distance between the sowing positions (seeding areas) in the in-plane direction of the seedling raising material is not particularly limited, but is, for example, within the range of 10 mm to 30 mm, and preferably within the range of 15 mm to 25 mm. The area of ​​each sowing position (seeding area) is not particularly limited, but is, for example, 2 cm 2 Less than or equal to 1.5 cm, for example 2 Less than or equal to 1cm 2 For example, 0.8 cm or less.2 Less than or equal to 0.5cm 2 Less than or equal to 0.25cm 2 The number of sowing positions (seeding regions) in the seedling raising material is not particularly limited, and may be, for example, 5 or more, 10 or more, 20 or more, 30 or more, 40 or more, 50 or more, 60 or more, 70 or more, 80 or more, 90 or more, or 100 or more. The upper limit of the number of sowing positions (seeding regions) in the seedling raising material is not particularly limited, and may be determined according to ease of handling, and may be, for example, 1000 or less, 500 or less, 400 or less, 300 or less, 200 or less, or 150 or less.

[0023] Although the method of watering the planar seedling raising material is not particularly limited, usually, at least the bottom surface of the seedling raising material is immersed in water to supply moisture to the sown seeds. Note that, until germination, water may be preferable as the moisture, but after germination, a nutrient solution may be used as the moisture.

[0024] The environmental temperature in the seedling raising step is not particularly limited as long as it is a temperature at which kale can germinate and grow, but is preferably a temperature in the range of 10°C or higher and lower than 30°C, more preferably a temperature in the range of 10°C or higher and 26°C or lower, and even more preferably a temperature in the range of 15°C or higher and 25°C or lower. The place where the seedlings are raised may be artificially heated or cooled to control the environmental temperature within a desired range. It may be more preferable to carry out the seedling raising step in a closed facility where the seedling raising environment can be controlled. The light irradiation conditions in the seedling raising step are not particularly limited, but may be, for example, a condition in which a short light period (e.g., 0.1 to 0.5 hours) and a short dark period (e.g., 0.1 to 0.5 hours) are alternately repeated. Note that there may be only a dark period and no light irradiation until the seeds germinate.

[0025] (Temporary planting process carried out as necessary) As a part of the seedling raising process, a step of temporarily planting kale seedlings may be carried out as necessary. The step of temporarily planting kale seedlings is a step of planting kale seedlings at closer intervals than the step of permanent planting described later, cultivating them hydroponically, and raising seedlings for permanent planting. The temporary planting step can be carried out in accordance with the step of permanent planting, except that the intervals at which the seedlings are planted are narrower.

[0026] [2. How to grow kale hydroponically] (Method overview) A method for hydroponically cultivating kale according to one embodiment of the present invention is a method for hydroponically cultivating kale using a panel having a plurality of holes for planting seedlings, and includes a step of planting a plurality of seedlings in each of the holes.

[0027] (Planting process) The planting (transplanting) of kale seedlings is carried out on a panel having a number of holes for planting the seedlings in. Specifically, a number of kale seedlings are planted in each of the holes in the panel.

[0028] The number of kale seedlings planted in each hole of the panel is more than one, preferably 2, 3, or 4, and more preferably 3 or 4. When five or more kale seedlings are planted in the holes of the panel, there is a tendency for a large difference in growth between the seedlings planted in the same hole, and there is a tendency for defective products (plant bodies smaller than the standard size) to be produced compared to when four or fewer seedlings are planted in a hole. Furthermore, compared to when four or fewer seedlings are planted in a hole, each plant is smaller and more likely to be weak, and the petioles and stems tend to snap easily at the time of harvest.

[0029] Also, when three kale seedlings are planted in each hole, there is less of a difference in growth between the seedlings planted in the same hole, and there is less tendency for defective products (plants smaller than the standard size) to occur, compared to when four seedlings are planted in each hole. Furthermore, compared to when four seedlings are planted in each hole, each plant is larger, and there is even less chance of the petioles and stems (main axes) snapping off at harvest.

[0030] Furthermore, when two kale seedlings are planted in each panel hole, there is a tendency for differences in growth to be more pronounced, especially in the early stages of growth after planting, compared to when three seedlings are planted in each hole. However, by selecting the nutrient solution used for hydroponic cultivation (selecting a nutrient solution with a relatively high nitrogen content) and adjusting the cultivation period after planting, etc., it is possible to reduce the differences in growth between seedlings.

[0031] The total yield (including defective products) per panel tends to be greatest when three or four kale seedlings are planted per hole. In some cases, the total yield (including defective products) per panel is greatest when five or more kale seedlings are planted per hole, but because the percentage of defective products (plants that are below the standard size) is higher and the percentage of crops with snapped petioles and stems is also higher, the yield per panel tends to be greatest when three or four kale seedlings (especially when three) are planted per hole.

[0032] The planting interval of the kale seedlings is not particularly limited, but preferably, the interval between the multiple holes in the panel into which the seedlings are planted is more than 5 cm and not more than 25 cm. The interval between the holes refers to the distance from the center of the hole A into which the seedlings are planted to the center of the hole B into which the seedlings are planted, and the holes A and B are adjacent holes into which the seedlings are planted. As a result, the seedlings are planted so that the interval between adjacent seedlings (the interval between the main axes at the ground level of the seedlings planted in the adjacent holes) is generally more than 5 cm and not more than 25 cm. By planting in this way, a kale harvest having properties suitable for eating raw, for example, for salads, can finally be obtained. In addition, competition between the plants is appropriately promoted, which may lead to an increase in yield. The lower limit of the interval between the multiple holes into which the seedlings are planted is preferably 6 cm or more, more preferably 7 cm or more, and even more preferably 8 cm or 9 cm or more. The upper limit of this distance is preferably 23 cm or 22 cm or less, more preferably 20 cm or less, even more preferably 16 cm or 15 cm or less, and particularly preferably 12 cm or 11 cm or less. When seedlings are planted in rows, the spacing between adjacent seedlings in the same row (the spacing between holes in the row direction in which the seedlings are planted) and between adjacent seedlings in adjacent rows (i.e., the spacing between rows, i.e., the spacing between holes in the row direction in which the seedlings are planted) are planted so that the spacing is greater than 5 cm and less than 25 cm. In this case, the density of the seedlings planted is in the range of more than 16×n and less than 400×n per square meter, preferably, for example, in the range of 20×n or 25×n or more and 300×n or less per square meter, and in the range of 20×n or 25×n or more and 100×n or 120×n or less per square meter. Here, n (an integer of 2 or more) refers to the number of seedlings planted in one hole.

[0033] The number of kale seedlings planted at the above intervals is not particularly limited, and may be, for example, 10 or more, 50 or more, 100 or more, 200 or more, 300 or more, 400 or more, 500 or more, 1000 or more, 5000 or more, 10000 or more, or 100000 or more. There is no particular upper limit on the number of seedlings that can be planted, and it is only limited by the area in which the seedlings can be planted.

[0034] Kale seedlings may be planted manually or using a planting machine or the like.

[0035] (Panel for planting seedlings) The panel on which the seedlings are planted may be any of various panels used in hydroponic cultivation. The size of the panel, the number of holes in the panel, the size of the holes, the spacing between the holes, etc. are not particularly limited. Examples of the panel include various plastic panels and polystyrene foam panels.

[0036] (Kale seedlings ready to be planted) The method for producing kale seedlings is not particularly limited, but the seedlings are preferably produced by the above-mentioned [1. Method for producing kale seedlings]. The seedlings produced at each sowing position in the planar seedling raising material by this manufacturing method are cut out from the planar seedling raising material as a unit (hereinafter, block) including one sowing position (seeding area). This block is composed of the seedling raising material including one sowing position (seeding area) and multiple seedlings growing therein. This block may be of any size as long as it can be fitted into and fixed in a hole in a panel in which the seedlings are planted. In a typical example, when the hole in the panel in which the seedlings are planted is circular and the block is approximately cubic, the block is cut out so that the length of one side of the block is approximately the same as the diameter of the hole in the panel. The length of one side of the block is, for example, 0.8 times or more, preferably 0.9 times or more, 0.95 times or more, or 1 times or more, and 1.5 times or less, 1.4 times or less, 1.3 times or less, or 1.2 times or less, of the diameter of the hole in the panel. The diameter of the circular hole in the panel is, for example, in the range of 1.5 cm or more and 3 cm or less, more typically 1.8 cm or more and 2.5 cm or less. In addition, the planar seedling material may have a cut line or something equivalent to the cut line for cutting out each block.

[0037] Then, by fitting the above-mentioned blocks into the holes of the panel in which the seedlings are to be planted, the seedlings corresponding to the respective sowing positions of the planar seedling raising material (such as a urethane mat) can be planted as multiple seedlings in the holes of the panel. In a preferred example, a block containing 2, 3, or 4 seedlings per sowing position obtained by sowing 2, 3, or 4 seeds in each of the multiple sowing positions is planted as multiple seedlings in the holes of the panel. In a particularly preferred example, a block containing 3 seedlings per sowing position obtained by sowing 3 seeds in each of the multiple sowing positions is planted as multiple seedlings in the holes of the panel.

[0038] (Cultivation process after planting) After planting the kale seedlings on the hydroponic panel, hydroponic cultivation is performed using the hydroponic cultivation system in which the panel is installed. The kale seedlings may be planted while the panel is installed in the hydroponic cultivation system, or the seedlings may be planted on the panel before installation in the hydroponic cultivation system, and the panel after completion of planting may be installed in the hydroponic cultivation system. In a typical example, hydroponic cultivation is performed by supplying a nutrient solution to the roots of the kale seedlings. The type of nutrient solution and the method of supplying the nutrient solution can be widely adopted from those used in hydroponic cultivation. Examples of the method of supplying the nutrient solution include, but are not limited to, the DFT method, the NFT method, and the spray method.

[0039] The environmental temperature in the cultivation step is not particularly limited as long as it is a temperature at which the plant can grow, but is preferably in the range of 10°C or higher and lower than 30°C, more preferably in the range of 10°C or higher and 26°C or lower, and even more preferably in the range of 15°C or higher and 25°C or lower. The cultivation location may be artificially heated or cooled to control the environmental temperature within a desired range. From the viewpoint of enabling a constant supply of cultivated kale throughout the year, facilitating control of the hardness of the cultivated kale stems and leaves within a suitable range, and preventing damage by insects and the like, it is preferable that the cultivation step is carried out in a facility separated from the external environment. The facility in which the cultivation step is carried out may be, for example, a sunlight-type plant cultivation facility or a closed-type (artificial light irradiation-type) plant cultivation facility.

[0040] (Harvesting process) In the kale harvesting process, the kale obtained by the above-mentioned cultivation process is preferably harvested by "stalk harvesting". In this specification, "stalk harvesting" refers to a harvesting method in which the main axis (stem) of the kale is cut to harvest the main axis and the multiple leaves attached to the main axis with the multiple leaves still attached. In other words, this is a harvesting method that differs from "leaf harvesting" (i.e., a harvesting method in which leaves are cut off one by one from the petiole), which is a common harvesting method for kale. The stalk harvested kale preferably includes the tip of the main axis of the kale (terminal bud).

[0041] Kale harvesting may be performed so that the leaves closest to the ground (when referred to as the first leaf, second leaf, etc. from the closest to the ground, for example, the first leaf, the second leaf, the third leaf, the fourth leaf, etc.) are left unharvested, or the harvest may include the first leaf as well (i.e., all leaves are included). Kale harvesting is preferably performed so that the harvest includes the first leaf as well.

[0042] Kale harvested by cutting is preferably in a state where 1) the number of primary leaves is in the range of 5 to 15, or 2) the seedlings have been cultivated for 20 to 55 days after planting. By satisfying at least one of conditions 1) and 2), and preferably both, a kale harvest that is even more suitable for eating raw can be obtained.

[0043] In the above state 1), the lower limit of the number of true leaves may be more preferably 6 or more, 7 or more, 8 or more, or 9 or more, and the upper limit of the number of true leaves may be more preferably 14 or less, 13 or less, 12 or less, or 11 or less. In the above state 2), the seedlings may be more preferably cultivated for 20 to 50 days after planting, and further preferably cultivated for 25 to 45 days or less, or 35 days or less.

[0044] (A process that is carried out as necessary after the harvesting process) The kale roots obtained by the harvesting step may be subjected to at least one, and preferably all, of the following treatments A) to C) as necessary. A) Removal of unnecessary leaves: For example, yellowed leaves, damaged leaves, and leaves that are too numerous for sale are removed from the main stem of the harvested kale. B) Trimming the main stem: For example, the lower part of the main stem of a harvested kale plant (the side that was cut when harvested) is trimmed slightly to create a fresh cut surface and to a suitable length for sale. C) Packaging treatment: The harvested kale is packaged using a bag, packaging film, wrap, etc. The harvested kale is preferably one that has been subjected to the above-mentioned treatments A) and B).

[0045] By adopting the method for hydroponic cultivation of kale according to one embodiment of the present invention, the total yield per panel can be increased. Furthermore, kale that satisfies at least one (preferably all) of the following conditions can be obtained at a relatively high yield: 1) the mesophyll is thin and soft, 2) the leaf size is small (e.g., about 8 to 15 cm in diameter), and 3) the main stem is also soft. This kale may also have a tendency to be less bitter and easier to eat than kale cultivated by a conventional method. EXAMPLES

[0046] Example 1 An embodiment of the present invention will be described below.

[0047] (Sowing to seedling raising process) A urethane mat measuring 58 cm x 28 cm (Ematsu Kasei Co., Ltd.) was used as the urethane mat for sowing seeds. This urethane mat was divided into blocks so that blocks of approximately 2 cm square could be cut out, but no holes for sowing seeds were provided. After allowing the urethane mat to absorb water sufficiently and removing the air, seeds of the kale variety Samba Carnival (a variety from Masuda Seed Co., Ltd.) were sowed. The seeds sowed were of high quality, with a germination rate of 90% or more in a normal germination test. Five types of urethane mats were prepared, with one, two, three, four, or five seeds sowed in the center of each frame (sowing position / sowing area). In other words, the distance between adjacent sowing positions was approximately 2 cm, and there was virtually no distance between seeds sown in the same sowing position (in the case of multiple seeds sowing).

[0048] After sowing, the urethane mats were stored in commercially available seedling raising boxes, and the process from germination to seedling raising was carried out in a closed facility that did not allow sunlight to enter. Light irradiation was performed by repeating ON / OFF of LED irradiation every 15 minutes. Watering was performed by misting once a day. Temperature conditions were kept at 25°C, and humidity was not controlled.

[0049] Figure 1 shows the state of germination on a urethane mat. As shown in Figure 1, the 100% germination rate for each frame (sowing position) showed a tendency to increase as the number of seeds sown increased in the range of 1 to 5 seeds per frame, reaching nearly 100% when 5 seeds were sown. Also, a very clear difference was observed in the 100% germination rate for each frame between when 1 seed was sown and when 2 seeds were sown.

[0050] (Planting process) In the seedling raising process, when the kale seedlings had just started to develop one true leaf or before that (when the cotyledons had developed and the true leaves were just starting to become visible, 10-14 days after sowing), the blocks were separated one by one and planted in hydroponic panels. The blocks used for planting were selected from those that showed a 100% germination rate in all cases, with one, two, three, four or five seedlings planted in the holes of the panel. Three types of polystyrene foam panels A, B and C (longitudinal 87-87.5 cm x transverse 57.5-58.5 cm) with different numbers of holes but almost the same panel area were used for hydroponic cultivation. Kale seedlings were planted in a total of 44 holes, 11 long and 4 short, in polystyrene foam panel A. The distance between adjacent holes in the long direction was all 8 cm, and the distance between adjacent holes in the short direction was 15 cm, approximately 11 cm, and 15 cm, respectively. Kale seedlings were planted in a total of 28 holes (7 long holes x 4 short holes) on polystyrene foam panel B. The distance between adjacent holes in the long direction was all 14 cm, and the distance between adjacent holes in the short direction was 14 cm, approximately 11 cm, and 14 cm, respectively. Kale seedlings were planted in a total of 32 holes (8 long holes x 4 short holes) on polystyrene foam panel C. The distance between adjacent holes in the lengthwise direction was all 11 cm, and the distance between adjacent holes in the short direction was 14 cm, approximately 11 cm, and 14 cm, respectively. For each of the polystyrene foam panels A, B, and C, five types of panels were prepared: a panel with one seedling planted in each hole, a panel with two seedlings planted in each hole, a panel with three seedlings planted in each hole, a panel with four seedlings planted in each hole, and a panel with five seedlings planted in each hole.

[0051] (Cultivation process after planting) The cultivation process after planting the seedlings on the panels was carried out in a solar-powered plant factory. Specifically, polystyrene foam panels A, B, and C on which the seedlings were planted were placed on a hydroponic cultivation bed that stored nutrient solution, and hydroponic cultivation was carried out while circulating the nutrient solution using the DFT method. The nutrient solution used was No. 1 TF Full Mix A + No. 2 TF Full Mix B (both manufactured by Toyotane Corporation), which was automatically mixed to achieve a concentration of EC3.00. During the cultivation process, the temperature inside the plant factory was controlled at 25°C and humidity at around 60%.

[0052] (Harvesting process) On the 26th day after planting, the kale obtained from the cultivation process was harvested by "stalk harvesting". Stalk harvesting was performed so that the harvest included the first leaf (i.e., all leaves).

[0053] (evaluation) Of the kale plants harvested, those weighing less than 5g per plant were deemed to be non-standard (too small to be sold commercially), and those weighing more than 5g per plant were deemed to be within the standard. As shown in Figure 2, in all cases of polystyrene foam panels A, B, and C, when 1 to 3 seeds were sown, all plants were within the standard. On the other hand, when 4 seeds were sown, there were cases where non-standard plants were mixed in, and when 5 seeds were sown, there were even more cases where non-standard plants were mixed in. Note that Figure 2 shows the results for one hole out of the holes that showed average growth conditions within each polystyrene foam panel. In addition, when sowing 4 or 5 seeds, there was an impression that many plants had stems and petioles that were too thin and broke during manual harvesting. Therefore, sowing 3, 2, or 1 seed is easier to harvest and further reduces the risk of damage to the harvested crop. When comparing sowing 2 and 3 seeds, sowing 3 seeds tended to have fewer wins and losses between plants and more uniform stem sizes. In other words, sowing 3 seeds is superior in terms of the rate of excellent products and ease of harvesting. When sowing 1 or 2 seeds, the number of seeds is relatively small, such as when sowing 1 or 2 seeds, the leaves of the plant tend to spread out horizontally and the growth of the plant height tends to be slow. As for the total yield per panel, as shown in Figure 3, sowing three seeds is significantly larger than sowing one or two seeds. There were also cases where sowing four or five seeds produced a larger total yield per panel than sowing three seeds, but the difference in total yield was not that large.

[0054] Example 2 (Sowing to seedling raising process) A urethane mat measuring 58 cm x 28 cm (Ematsu Kasei Co., Ltd.) was used as the urethane mat for sowing seeds. This urethane mat was divided into blocks so that blocks of approximately 2 cm square could be cut out, but no holes for sowing seeds were provided. After the urethane mat was sufficiently absorbed with water and the air was removed, seeds of the kale variety Wild Kitchen (a variety from Masuda Seed Co., Ltd.) were sowed. The seeds sowed were of high quality, with a germination rate of 90% or more in a normal germination test. Urethane mats were prepared with one, two, three, four, or five seeds sowed in the center of each frame (sowing position / sowing area). In other words, the distance between adjacent sowing positions was approximately 2 cm, and there was practically no distance between seeds sown in the same sowing position (in the case of multiple seeds being sown). The frames used to check the germination rate were 10 frames each of the following: frames where one seed was sown, frames where two seeds were sown, frames where three seeds were sown, frames where four seeds were sown, and frames where five seeds were sown.

[0055] After sowing, the urethane mats were stored in commercially available seedling raising boxes, and the process from germination to seedling raising was carried out in a closed facility that did not allow sunlight to enter. Light irradiation was performed by repeating ON / OFF of LED irradiation every 15 minutes. Watering was performed by misting once a day. Temperature conditions were kept at 25°C, and humidity was not controlled.

[0056] The germination rate in the frames where seeds were sown one at a time was 90% (9 out of 10 seeds germinated), meaning that all but one of the 10 frames germinated. The germination rate in the frames where seeds were sown two at a time was 100% (20 out of 20 seeds germinated). The germination rate in the frames where seeds were sown three at a time was 97% (29 out of 30 seeds germinated), meaning that one seed did not germinate in one of the 10 frames. The germination rate in the frames where seeds were sown four at a time was 98% (39 out of 40 seeds germinated), meaning that one seed did not germinate in one of the 10 frames. The germination rate in the frames where seeds were sown five at a time was 92% (46 out of 50 seeds germinated), meaning that all seeds germinated in seven of the 10 frames, four seeds germinated in two frames, and three seeds germinated in one frame. In other words, in terms of the seed germination rate, sowing two seeds resulted in 100%, while sowing three and four seeds was close to 100%, and sowing five seeds also exceeded the rate of sowing one seed.

[0057] (Planting process) In the seedling raising process, when the kale seedlings start to develop one true leaf or before that (when the cotyledons develop and the true leaves start to be seen, 10 to 14 days after sowing), the blocks were separated one by one and planted in a hydroponic panel. The purpose here is to confirm whether a similar tendency to that in Example 1 is observed when three or more seedlings are planted. The blocks used for planting were selected from those that showed a 100% germination rate in any case where one seed, three seeds, four seeds, or five seeds were planted, and planting of one, three, four, or five seedlings in the holes of the panel was realized. The blocks used for planting were 28 blocks each for planting one, three, four, or five seedlings, and were prepared separately from those used for confirming the germination rate. The polystyrene foam panel C described in Example 1 was used as the hydroponic panel. A total of 28 kale seedlings were planted in polystyrene foam panel C, with 7 long holes and 4 short holes. The distance between adjacent holes in the long direction was all 11 cm, and the distance between adjacent holes in the short direction was 14 cm, approximately 11 cm, and 14 cm, respectively. A panel with one seedling planted in each hole, a panel with three seedlings planted in each hole, a panel with four seedlings planted in each hole, and a panel with five seedlings planted in each hole were prepared.

[0058] (Cultivation process after planting to harvesting process) The cultivation process after planting the seedlings on the panels was carried out in a sunlight-type plant factory in the same manner as described in Example 1, and the kale obtained by the cultivation process was harvested by "stalk harvesting." Stalk harvesting was carried out so that the harvested product included the first leaf (i.e., all leaves).

[0059] (evaluation) Of the kale plants harvested, those with a weight of 5g or less per plant were deemed to be outside the standard, while those with a weight of over 5g per plant were deemed to be within the standard. Also, when 4 or 5 seeds were sown, it seemed that many plants had stems and leaf stalks that were too thin and broke during the manual harvesting process. Detailed results are shown in Figure 4. Note that Figure 4 shows the results for one hole out of the holes that showed an average growth state within each polystyrene foam panel. [Industrial Applicability]

[0060] The invention can be used in the agricultural sector, especially with regard to the cultivation of kale.

Claims

1. A method for producing kale seedlings for hydroponic cultivation, comprising a step of sowing multiple kale seeds at each of a plurality of sowing positions on a planar seedling material.

2. The method of claim 1 , wherein two, three or four of the kale seeds are sown in each of a plurality of seeding positions.

3. 2. The method according to claim 1, wherein the planar seedling raising material is a urethane mat.

4. A method for hydroponically cultivating kale using a panel having a plurality of holes for planting seedlings, comprising: Planting 2, 3 or 4 kale seedlings into each of the holes.

5. The method according to claim 4, wherein the kale seedlings produced by the method according to claim 1 corresponding to each of the sowing positions are planted as two, three or four of the kale seedlings.

6. A method according to claim 4, in which, in the manufacturing method described in claim 2 or 3, three kale seeds are sown in each of a plurality of sowing positions, and three kale seedlings are obtained per sowing position, and then planted in each of the holes.

7. The method according to claim 4, wherein the spacing between the holes in the panel into which the kale seedlings are planted is greater than 5 cm and not greater than 25 cm.

8. The method according to claim 4, further comprising a harvesting step of harvesting the obtained kale by cutting.

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