Method for growing refrigerated seedlings of field wasabi

Abstract

To provide a method for growing refrigerated seedlings of field wasabi that can shorten the growth period from seedlings to mature plants and can grow refrigerated seedlings that can increase the yield of field wasabi.SOLUTION: A growing method 1 comprises: a step 1 being a germination / seedling step of germinating field wasabi seeds; a step S2 being a refrigeration step of refrigerating the field wasabi seedlings at a refrigeration temperature of 2 to 5°C for a fixed period of time to create refrigerated seedlings; and a step S3 being a growing step of planting, in a field, and growing the refrigerated seedling.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for growing wasabi seedlings, and in particular to a method for growing refrigerated field wasabi seedlings by refrigerating field wasabi seedlings under specified conditions to grow refrigerated field wasabi seedlings. [Background technology]

[0002] Traditionally, wasabi seedlings die when temperatures exceed approximately 25°C, making it difficult to grow them in the summer. This is one of the reasons why wasabi harvests have not increased. The same species of wasabi is called field wasabi or water wasabi depending on the cultivation method. The former is grown in ordinary fields, where the petioles and leaf blades are harvested. The latter is grown in wasabi fields that use mountain streams and spring water, where the rhizomes are harvested. For this reason, the conventional cultivation method for field wasabi is to raise young field wasabi seedlings for about a year in forested fields in cool, highland regions, and then plant the seedlings in shaded plastic greenhouses and leave them to grow for a further seven to eight months until they reach a mature plant size that can be harvested. However, the above cultivation method had the problem that it took a long time, about 20 months, for the seedlings to grow into mature plants.Furthermore, it required work such as transporting the field wasabi seedlings to high, cold areas and lowering them into pipe greenhouses, which required a lot of work and cost. In recent years, techniques have been developed to reduce such burdens, and inventions relating to these techniques have already been disclosed.

[0003] Patent Document 1 discloses an invention titled "Method for Cultivating Wasabi Seedlings" that relates to a method for cultivating wasabi seedlings in an artificial environment. The invention disclosed in Patent Document 1 will be described below. The invention disclosed in Patent Document 1 is a method for cultivating wasabi seedlings, which is characterized by sowing wasabi seeds in a state where the cotyledons are contained within the seed shell and the 3-7 mm root has hairy lateral roots, while supplying water that may contain a nutrient solution and light to a cultivation medium in an artificial facility maintained at 18-20°C, and cultivating the seeds until the cotyledons germinate and develop, and then the cotyledons are replaced by 4-6 true leaves. In an invention with these characteristics, wasabi seedlings are grown in an artificial facility, so by locating this artificial facility near wasabi fields, it is possible to grow wasabi seedlings all year round and reduce transportation costs. In addition, because wasabi fields can maintain an environment of around 20°C thanks to spring water, the survival rate of wasabi seedlings can be approximately 100%, even when planted in July. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 5993156 Summary of the Invention [Problem to be solved by the invention]

[0005] However, it is unclear whether the invention disclosed in Patent Document 1 can be applied to field wasabi. Furthermore, there is no description as to whether the cultivated wasabi seedlings shorten the growth period from a young seedling to a mature plant of a sufficient harvestable size. Therefore, it is unclear whether the invention disclosed in Patent Document 1 sufficiently solves the problem of the lengthening of the time it takes to grow into a mature plant. Furthermore, although the invention disclosed in Patent Document 1 achieves a survival rate of approximately 100% for wasabi seedlings even when planted in July, there is no mention of whether it is possible to prevent the seedlings from dying due to high temperatures after planting. Therefore, it is unclear whether the invention disclosed in Patent Document 1 fully resolves the issue of wasabi yields not increasing due to high temperatures.

[0006] The present invention has been made in response to such conventional circumstances, and has an object to provide a method for growing refrigerated seedlings of field wasabi that can shorten the growth period from seedlings to mature plants and produce refrigerated seedlings that can increase the yield of field wasabi. [Means for solving the problem]

[0007] In order to achieve the above object, the first invention is characterized by comprising a refrigeration step of refrigerating field wasabi seedlings at a refrigeration temperature of 2 to 5°C for a fixed period of time to produce refrigerated field wasabi seedlings. In the invention having such a configuration, the young seedling refers to a seedling that has reached a predetermined growth state, for example, a seedling that has reached a certain number of primary leaves or an area thereof, although the predetermined growth state can be defined arbitrarily. In addition, the method of cultivating the seeds of field wasabi in a cultivation medium, germinating them, and cultivating the germinated seeds into seedlings is not particularly limited. Furthermore, in this process, the field wasabi seedlings may or may not be irradiated with artificial light. In the present application, the terms "seedlings" and "mature plants" refer to the degree of growth of field wasabi seedlings, and the term "refrigerated seedlings" refers to the state of the seedlings while they are refrigerated in the refrigeration process.

[0008] In the invention having the above configuration, it is believed that by refrigerating field wasabi seedlings for a certain period of time at a refrigeration temperature of 2 to 5°C, dormancy is induced in the seedlings, and then dormancy is broken. Refrigeration is performed by storing the seedlings in, for example, a refrigerator. The certain period of time is adjusted according to the outside temperature, for example, so as to prevent the seedlings from dying due to high temperatures, or to reduce the cost of artificially refrigerating the seedlings before the refrigeration process. When the seedlings that have broken dormancy, i.e., the refrigerated seedlings, are planted in a field, they begin to grow rapidly.

[0009] The second invention is a method for producing a wasabi plant having a photosynthetic photon flux density of 2 to 30 μmol / m2 on a cultivation surface without the seedlings, the method comprising the steps of: irradiating light onto the seedlings of field wasabi in the refrigeration step; 2 / s. In the invention having such a configuration, for example, an LED lamp for plant growth is suitably used as the light source.

[0010] In the invention having the above configuration, in addition to the effect of the first invention, the photosynthetic photon flux density is increased to 2 μmol / m 2 / s or more, the growth of seedlings can be stably maintained at a refrigerated temperature of 2 to 5°C. 2 / s or less, the occurrence of photoinhibition at the same refrigeration temperature is prevented.

[0011] Next, the third invention is characterized in that in the first or second invention, the certain period is 5 to 6 months. In an invention configured in this way, in addition to the effects of the first or second invention, because the fixed period of refrigeration is 5 to 6 months, the entire high temperature period unsuitable for the growth of field wasabi (for example, late spring to summer) can be used as a dormant period for the seedlings.

[0012] Furthermore, a fourth invention is characterized in that, in the first or second invention, it further comprises, after the refrigeration step, a growing step of planting and growing the refrigerated field wasabi seedlings in a field, and that the planting is carried out during a period when the maximum temperature in the field is 25°C or below.

[0013] In an invention having such a configuration, in addition to the effects of the first or second invention, planting is carried out when the maximum temperature in the field is below 25°C, thereby preventing the death of refrigerated seedlings due to high temperatures after planting. Effect of the Invention

[0014] According to the first invention, by providing a refrigeration process, the refrigerated seedlings begin to grow rapidly, so it is expected that the seedlings will grow into mature plants in a short period of time. In addition, when the seedlings are stored in a refrigerator, there is no need to transport the field wasabi seedlings to high altitudes or lower them into pipe greenhouses, completely resolving the issue of the large burden of labor and cost.

[0015] According to the second invention, in addition to the effects of the first invention, the photosynthetic photon flux density is increased to 2 to 30 μmol / m 2 By using this method, the growth of seedlings can be stably maintained at a refrigeration temperature of 2 to 5°C and photoinhibition can be prevented, thereby reducing the number of missing plants and enabling the seedlings to grow uniformly.

[0016] According to the third invention, in addition to the effects of the first or second invention, high temperature periods that are unsuitable for field wasabi growth can be utilized entirely as a dormant period for the seedlings, and so high temperature periods, where previously it was a major challenge to prevent the seedlings from dying, can be converted into a preparatory period for the seedlings to begin rapid growth, making it possible to actively and effectively utilize this period. Furthermore, if the chilling process is started in the spring, for example, the outside air temperature before the chilling process (specifically, the period from sowing to raising the seedlings) is usually lower than about 25° C., so it is not necessary to artificially chill the seeds or seedlings before the chilling process. As a result, the seedlings can be raised at low cost before the chilling process.

[0017] According to the fourth invention, in addition to the effects of the first or second invention, the death of seedlings due to high temperatures after planting is avoided, so it is possible to solve the conventional problem of not increasing the yield of field wasabi. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a process diagram of a refrigerated seedling growing method for field wasabi according to Example 1. [Diagram 2] FIG. 2 is a front view showing the inside of a refrigerator used in a refrigeration step constituting the refrigerated field wasabi seedling growing method according to the first embodiment. [Diagram 3] 1 is a table showing the effect of light intensity on refrigerated field wasabi seedlings produced by the method for growing refrigerated field wasabi seedlings according to Example 1. [Figure 4] 13 shows images of refrigerated field wasabi seedlings when irradiated with light of different intensities during the refrigeration process. [Diagram 5] 2(a) to 2(d) are graphs showing the seedling qualities of refrigerated field wasabi seedlings produced by the refrigerated field wasabi seedling growing method according to Example 1. [Figure 6] 1 is a graph showing the growth status of refrigerated field wasabi seedlings during the growth process in Example 1. [Figure 7] 4 is an image showing the growth status of refrigerated field wasabi seedlings during the growth process according to Example 1. [Figure 8] 4 is an image showing the growth status of refrigerated field wasabi seedlings during the growth process according to Example 1. [Figure 9] 1 is a table showing the yield of mature field wasabi plants at the completion of the growth process in Example 1. [Figure 10] The top row is a PPFD of the light irradiated in the refrigeration step constituting the method for growing refrigerated field wasabi seedlings according to Example 2, and the bottom row is an image of refrigerated field wasabi seedlings corresponding to the PPFD in the top row. [Figure 11] FIG. 11 is a scatter diagram plotting points corresponding to the PPFD of light irradiated in the chilling step constituting the method for growing chilled field wasabi seedlings according to Example 2 and the SPAD values ​​of the chilled seedlings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS EXAMPLES

[0019] The method for growing refrigerated seedlings of field wasabi according to the first embodiment of the present invention will be described in detail with reference to Fig. 1 to Fig. 9. Fig. 1 is a process diagram of the method for growing refrigerated seedlings of field wasabi according to Example 1. 1, the method for growing refrigerated seedlings of field wasabi (hereinafter referred to as the growing method) 1 according to Example 1 includes a germination / seedling process in step S1, a refrigeration process in step S2, and a growing process in step S3. Each process will be described below in order.

[0020] First, the germination and seedling process of step S1 is a process in which field wasabi seeds are germinated to produce seedlings 10 (see Figure 2). In this process, the seeds are first soaked in an aqueous solution containing 100 ppm gibberellin by weight, and the soaked seeds are then sown in a seedling medium formed in a cell tray, for example, and maintained in a pipe house (around March to April) with a maximum temperature of 25°C or less. This results in germinated field wasabi seeds.

[0021] The germinated seeds are then grown until they become seedlings 10 in a predetermined growth state. In this step, the predetermined growth state can be defined as, for example, a state in which the seedlings have grown to two primary leaves. However, other definitions may be adopted as long as seedlings 10 in a certain growth state are obtained. This step is a known step.

[0022] Next, the refrigeration step of step S2 is a step in which the field wasabi seedlings 10 grown in the germination and seedling step of step S1 are stored in a refrigerator 3, the refrigeration temperature is maintained at 2 to 5° C., and refrigerated for a certain period of time to produce refrigerated field wasabi seedlings. During refrigeration, light is irradiated onto the grown field wasabi seedlings 10.

[0023] Next, the refrigeration device used in carrying out the growing method will be described with reference to Fig. 2. Fig. 2 is a front view showing the inside of a refrigerator used in the refrigeration step constituting the refrigerated field wasabi seedling growing method according to Example 1. As shown in FIG. 2, the refrigeration device 2 includes a refrigerator 3, a shelf 4 having multiple shelves 4A housed in the refrigerator 3, and light sources 5 installed on each of the shelves 4A. Furthermore, the field wasabi seedlings 10 created in the germination process of step S1 are grown in a seedling growing medium in a 128-hole cell tray 6 and placed on the upper surface 4a of the shelf board 4A. In detail, the seedlings 10 and the 128-hole cell tray 6 are housed inside a box-shaped bottom water-supply tray 7 placed on the upper surface 4a. Furthermore, a light source 5 for irradiating the seedlings 10 with light from above is installed on the underside 4b of the shelf 4. Specifically, this light source 5 is an LED lamp for growing plants that emits light with a wavelength of approximately 400 to 800 nm.

[0024] The light irradiated to the seedlings 10 has a photosynthetic photon flux density (hereinafter referred to as PPFD) of 5 to 30 μmol / m on the cultivation surface 8 of the seedling medium when the seedlings 10 are not present. 2 / s. Furthermore, the light source 5 is controlled by a control unit (not shown) having a timer function so as to repeatedly turn on and off every 12 hours, for example. Furthermore, the fixed period of refrigeration is 5 to 6 months.

[0025] The growing process in step S3 is a process in which the refrigerated seedlings of field wasabi created in the refrigeration process in step S2 are planted in a field and grown until they reach a harvestable size. This process makes it possible to actually obtain mature plants in a short growth period. Here, a field refers to farmland that does not have the function of retaining water, unlike the wasabi fields mentioned above. The planting is carried out when the maximum temperature in the field is below 25° C. Furthermore, in this process, the growth period from planting to harvesting is, for example, about 5 months. Therefore, in the case of the cultivation method 1, the fixed period of the refrigeration process in step S2 (5 to 6 months) and the growth period of the growth process in step S3 (about 5 months) add up to about 10 to 11 months. Therefore, in the case of the cultivation method 1, mature plants are harvested in about half the time compared to the conventional cultivation method, where it takes about 20 months for seedlings to grow into mature plants.

[0026] Next, the effect of the light intensity irradiated during refrigeration on the quality of field wasabi seedlings will be explained using Figures 3 and 4. Figure 3 is a table showing the effect of light intensity on refrigerated field wasabi seedlings produced by the method for growing refrigerated field wasabi seedlings according to Example 1. Figure 4 is an image of refrigerated field wasabi seedlings irradiated with light of different intensities during the refrigeration process. FIG. 3 shows the results of the cooling process in step S2, in which the refrigeration temperature is set to 5° C., and the PPFD of the light emitted by the light source 5 is set to 0, 30, 60, and 90 μmol / m 2 The figures show the plant height (cm), number of leaves (sheets), SPAD (leaf area distribution meter) value, above-ground dry matter (g), and below-ground dry matter (g) of the refrigerated seedlings when the temperature was changed to 100 / s. Note that all of these measurements are the average values ​​for eight refrigerated seedlings.

[0027] Here, among the measured values ​​shown in Fig. 3, 0, 30, 60, and 90 μmol / m 2 The SPAD values ​​per PPFD were 15.4, 19.5, 9.3, and 8.8, respectively. 2 / s, the SPAD value is 0.30μmol / m 2 This is about half the SPAD value at / s. The reason for this result is that the PPFD is 30 μmol / m 2 It is considered that when the PPFD exceeds 30 μmol / m / s, the light energy becomes excessive and photoinhibition is caused. Therefore, in the refrigeration process of step S2, at a refrigeration temperature of 5°C, 2 It was found that it is desirable not to exceed / s.

[0028] Next, Figure 4 shows images of refrigerated field wasabi seedlings when the PPFD was changed at a refrigeration temperature of 5°C, with 0, 30, 60, and 90 in the figure representing the PPFD of the light emitted by the light source 5. Additionally, the seedlings divided and arranged in four sections along the direction of the arrows in the figure represent the refrigerated seedlings for each section. As shown in Figure 4, the green leaf color (dark gray in the figure) has a PPFD of 30 μmol / m 2 / s, followed by 0, 60, and 90 μmol / m 2 / s. Also, the PPFD is 60 and 90 μmol / m 2 At 30 μmol / m 2 This is clearly an increasing trend compared to / s.

[0029] Furthermore, regarding the magnitude of PPFD, the trends in the intensity of green and the number of discolored leaves corresponded to the trends in the magnitude of the SPAD values ​​shown in Figure 3, so it is believed that the occurrence of photoinhibition could also be confirmed visually. Therefore, as is evident from the SPAD values ​​shown in Figure 3, at a refrigeration temperature of 5°C, the PPFD is 30 μmol / m 2 The finding that it is desirable not to exceed / s was visually supported by images of refrigerated seedlings.

[0030] Next, the quality of the refrigerated seedlings during the refrigeration process will be described in detail with reference to Fig. 5. Fig. 5(a) to Fig. 5(d) are graphs showing the quality of the refrigerated field wasabi seedlings produced by the method for growing refrigerated field wasabi seedlings according to Example 1. Specifically, Fig. 5(a) to Fig. 5(d) show the results when the refrigeration temperature in the refrigerator 3 is 2 to 5°C and the PPFD of the light emitted by the light source 5 is 0, 2, 5, and 10 µmol / m 2 13 is a graph showing the change in seedling quality over time when / s. Below, FIG. 5(a) to FIG. 5(d) will be explained in order.

[0031] First, in Fig. 5(a), the vertical axis is the dry matter mass (g) of the aboveground parts (petioles and leaf blades) of the chilled seedlings, and the horizontal axis is the date (month / day) on which the dry matter mass was measured. In all of Figs. 5(a) to 5(d), February 25 (2 / 25) is the date chilling began. As shown in Fig. 5(a), as the refrigeration period progressed, the aboveground dry matter mass increased from 0 μmol / m 2 / s, the concentration decreased from the day refrigeration started, and the PPFD was 2 μmol / m 2 In contrast, when the PPFD was 5 and 10 μmol / m 2 In the case of / s, the top dry matter content increased from the day of the start of chilling. The increase was greater as the PPFD increased.

[0032] Next, in Figure 5(b), the vertical axis is the dry matter mass (g) of the underground (root) parts of the chilled seedlings, and the horizontal axis is the date (month / day) on which the dry matter mass was measured. As shown in Fig. 5(b), as the refrigeration period progressed, the underground dry matter mass increased from 0.2 μmol / m 2 / s, the concentration decreased from the day refrigeration started, and the PPFD was 5 μmol / m 2 In contrast, when the PPFD was 10 μmol / m 2 In the case of / s, the amount of dry matter underground increased from the start of chilling.

[0033] Furthermore, in Figure 5(c), the vertical axis is the height of the chilled seedlings (cm) and the horizontal axis is the date on which the height was measured (month / day). As shown in Figure 5(c), the plant height increased with the refrigeration period from 0 μmol / m 2 / s, the PPFD is shorter than the start date of refrigeration and is 2, 5, or 10 μmol / m 2 In the case of / s, the period was longer than the start date of refrigeration.

[0034] In FIG. 5(d), the vertical axis represents the number of fresh leaves (sheets) of the chilled seedlings, and the horizontal axis represents the date (month / day) on which the number of fresh leaves was measured. As shown in Fig. 5(d), as the refrigeration period progressed, the number of fresh leaves increased from 0 μmol / m 2 / s, it decreased from the day refrigeration started, and it was 2 μmol / m 2 In contrast, when the PPFD was 5 and 10 μmol / m 2 In the case of / s, the number of fresh leaves increased from the start of chilling in both cases.

[0035] As shown in Figs. 3, 4 and 5(a) to 5(d), in the refrigeration step S2 in which the refrigeration temperature is 2 to 5°C, the PPFD at which the above-ground dry matter amount, the below-ground dry matter amount, the plant height and the number of live leaves are all maintained is 5 μmol / m 2 / s, and the PPFD at which the SPAD value does not decrease is 30 μmol / m 2 We can see that it is / s. Therefore, in the refrigeration step S2 where the refrigeration temperature is 2 to 5°C, the concentration is 5 to 30 μmol / m 2 In the case of / s, the growth of seedlings was maintained stably and the occurrence of photoinhibition was prevented.

[0036] Next, the growth status of the refrigerated seedlings after planting will be described in detail with reference to Fig. 6. Fig. 6 is a graph showing the growth status of the refrigerated field wasabi seedlings during the growing process according to Example 1, with the vertical axis being the plant height (cm) of the refrigerated seedlings and the horizontal axis being the date (month / day) on which the plant height was measured. Of the measurement dates, October 12th (10 / 12) is the planting date. The reason why the planting month was set to October is because the outside air temperature in the field is below 25°C. Furthermore, FIG. 6 shows the change over time in the height of refrigerated seedlings after planting in the field in the growth process of step S3, when field wasabi seeds were sown in the seedling medium in the germination process of step S1 in the months of March, April, and May.

[0037] As a comparative example, the change over time in plant height of field wasabi seedlings grown using conventional cultivation methods (hereinafter referred to as conventional seedlings) is also shown. The conventional seedling cultivation method involves seedlings of field wasabi germinated in the same manner as in the germination process of step S1, sown in a seedling raising medium in April, and then these seedlings are moved to a cool, highland area as described above and grown in artificial wasabi fields, and these grown seedlings are then planted in a field in October. Note that these plant heights are the average values ​​for 10 plants, three replicates each, for both refrigerated seedlings and conventional seedlings.

[0038] As shown in Figure 6, the plant height in the growth process of step S3 does not become shorter immediately after planting, regardless of whether the seeds were sown in the seedling medium in March, April, or May. This is because the roots of the refrigerated seedlings are maintained or sufficiently formed (5 and 10 μmol / m in Figure 5(b)). 2 This is thought to be because, due to the fact that the leaves are less likely to die after planting, the growth rate of newly grown primary leaves is also faster. Therefore, the plant height reached the same length of about 20 cm about one month after planting (November 14th), and grew to about 60 cm about five months after planting (March 8th). The plant height was still about 60 cm about 6 months after planting (April 10), and no change was observed from about 5 months after planting, so the peak of the plant height was determined to be about 5 months after planting. Therefore, in growing method 1, if the refrigerated seedlings are planted in October, mature plants can be harvested in early March of the following year.

[0039] In contrast, in the case of the conventional seedlings according to the comparative example, the plant height temporarily shortened to about 10 cm about one month after planting. This is thought to be because, unlike the refrigerated seedlings, the conventional seedlings do not have fully formed roots, so the leaves die after planting and the growth rate of the newly grown primary leaves is slow. After that, the plant height increases about one month later than the refrigerated seedlings in growth method 1, following a similar trend, and is seen to reach its peak about six months after planting. Thus, with conventional cultivation methods, if the seedlings are planted in October, the harvest of mature plants will be at least from April of the following year onwards. Therefore, cultivation method 1 is more effective than conventional cultivation methods in that it enables early harvesting.

[0040] In addition, the peak plant height of the conventional seedlings (approximately 55 cm) was shorter than the peak plant height of the refrigerated seedlings (approximately 62 cm). Therefore, the results suggest that method 1 is more effective than conventional cultivation methods in terms of yield and appearance of mature plants.

[0041] Next, the growth status of the refrigerated seedlings after planting in the field will be described. Figures 7 and 8 are images showing the growth status of the refrigerated field wasabi seedlings during the growth process according to Example 1. Figure 7 shows images of the refrigerated seedlings and conventional seedlings, the changes in plant height over time shown in Figure 6, taken on January 12th of the following year, three months after planting. Both the refrigerated seedlings and conventional seedlings were sown on April 8th and planted on October 12th. The refrigeration of the refrigerated seedlings began on May 15th. As shown in Figure 7, when comparing the appearance of refrigerated seedlings with that of conventional seedlings, for example, the refrigerated seedlings are clearly larger in terms of plant height and leaf area than the conventional seedlings.

[0042] Furthermore, Figure 8 shows images of the refrigerated seedlings shown in Figure 7 and the conventional seedlings taken one month later on February 9th, and it can be seen that the difference in growth between the refrigerated seedlings and the conventional seedlings confirmed in Figure 7 has been maintained. Thus, the effectiveness of cultivation method 1 compared to conventional cultivation methods was visually confirmed by the images of refrigerated seedlings in terms of yield and appearance of mature plants.

[0043] Furthermore, the yield of mature plants produced by the growing method 1 will be described with reference to Fig. 9. Fig. 9 is a table showing the yield of mature plants of field wasabi at the completion of the growing process according to Example 1. As shown in Figure 9, in growth method 1, when the seeds were sown in the seedling medium in March, April, and May, the yield of mature plants per 10 ares was 3,464 to 3,900 kg for above-ground parts (prepared weight) and 4,213 to 5,546 kg for round digging (above-ground parts + below-ground parts, prepared weight).

[0044] In contrast, for conventional seedlings, the above-ground part (prepared weight) was 1,615 kg, and for round-drilled seedlings (prepared weight) was 2,423 kg. In other words, the yield of mature plants from refrigerated seedlings grown using cultivation method 1 was approximately 2.1 to 2.4 times the yield for above-ground parts and 1.7 to 2.3 times for round-drilled seedlings compared to the yield for conventional seedlings. This demonstrates that cultivation method 1 is extremely effective compared to conventional cultivation methods, even in terms of yield. The date for measuring the yield was March 8th for both cultivation method 1 and the conventional cultivation method.

[0045] As explained above, the peak height in the growth process of step S3 is observed about 5 months after planting, regardless of the month of sowing, whereas the peak height in the case of conventional cultivation methods is about 6 months after planting. This result demonstrates that by providing the refrigeration process of step S2, the refrigerated seedlings that have broken dormancy begin to grow rapidly, and grow from young seedlings to mature plants in a short period of time.

[0046] Furthermore, the refrigeration step in step S2 is a simple process of storing field wasabi seedlings 10 in refrigerator 3 and setting the refrigeration temperature and PPFD within appropriate ranges, eliminating the need to transport field wasabi seedlings depending on the season and growth state, and eliminating the effects of abnormally high temperatures that have become prominent in recent years. Therefore, according to growth method 1, by providing the refrigeration step in step S2, it is possible to completely resolve the conventional issues of the large burden of labor and cost, and to ensure the harvest volume of mature field wasabi plants without being affected by climate change.

[0047] Furthermore, in the case of Growing Method 1, when refrigerated seedlings are planted in October, mature plants can be harvested in early March of the following year, resulting in less damage from pests and diseases compared to conventional cultivation methods where harvesting is delayed until at least April of the following year. Therefore, according to Growing Method 1, it is possible to obtain mature plants with excellent appearance and a high product unit price, and the effort required for shipping preparation can also be reduced.

[0048] In addition, the yield of mature plants was approximately 2.1 to 2.4 times that of above-ground parts and 1.7 to 2.3 times that of round digging, compared to the yield obtained using conventional cultivation methods. This result demonstrates that it is possible to increase the yield of field wasabi by incorporating the refrigeration process in Step S2. EXAMPLES

[0049] A method for growing refrigerated field wasabi seedlings according to a second embodiment of the present invention will be described in detail using Figures 10 and 11. The upper part of Figure 10 is a PPFD of light irradiated in the refrigeration step that constitutes the method for growing refrigerated field wasabi seedlings according to Example 2, and the lower part is an image of refrigerated field wasabi seedlings that corresponds to the PPFD in the upper part. First, there will be described the steps of a refrigerated seedling growing method for field wasabi (hereinafter referred to as the growing method) 1A according to Example 2. Like the growing method 1 according to Example 1, the growing method 1A comprises a germination / seedling step of step S1, a refrigeration step of step S2, and a growing step of step S3.

[0050] However, in growth method 1A, among the above steps, in the refrigeration process of step S2, the minimum PPFD value of light on the cultivation surface 8 (see Figure 2) of the seedling medium when there are no seedlings 10 is different from the minimum PPFD value in growth method 1 of Example 1. However, the germination conditions and seedling raising conditions in the germination / seedling process of step S1 in growth method 1A, the growth conditions in the growth process of step S3, and the refrigeration device 2 and light source 5 used are all the same as in growth method 1.

[0051] 10 are the PPFD of the light irradiated to the refrigerated seedlings in the refrigeration process of step S2 of the growth method 1 A. The refrigeration temperature is 2.4 to 4.1°C (average 3.1°C inside refrigerator 3). As shown in the top panel of Fig. 10, the PPFD ranges of light for multiple refrigerated seedlings arranged in four compartments are (1) 8.5–19, (2) 3.2–14.1, (3) 16.9–37.2, and (4) 15.6–78.7 μmol / m 2 / s.

[0052] Furthermore, as shown in the lower part of Figure 10, in all cases of PPFD (1) to (4), the growth of the refrigerated seedlings was maintained and they showed the same level of growth. Furthermore, the leaf color of the refrigerated seedlings is green (dark gray in the figure) when the PPFD is (1) or (2). In contrast, when the PPFD is (3) or (4), the leaf color of the refrigerated seedlings changes from white to yellow (white to grayish white in the figure). From these results, it is considered that photoinhibition occurred in refrigerated seedlings when PPFD was (3) or (4). Furthermore, as shown in Figures 3 and 4, the trend in the intensity of green represents the trend in the SPAD value, so it is believed that by determining the correlation between PPFD and the SPAD value, it is possible to determine the PPFD range in which an appropriate SPAD value can be obtained.

[0053] Therefore, the correlation between the PPFD and SPAD value of refrigerated seedlings will be explained using Figure 11. Figure 11 is a scatter diagram plotting points corresponding to the PPFD of light irradiated in the refrigeration step constituting the method for growing refrigerated field wasabi seedlings according to Example 2 and the SPAD value of the refrigerated seedlings, with the vertical axis representing the SPAD value and the horizontal axis representing the PPFD of light (μmol / m 2 / s).

[0054] As shown in Fig. 11, the SPAD value is expressed using a regression line for PPFD (dotted line in the figure, coefficient of determination 0.3992). This regression line shows that there is a negative correlation between the SPAD value and the stronger the PPFD, the lower the SPAD value becomes. Therefore, if the appropriate SPAD value is 15 or more, the regression line shows that the PPFD is 2 to 20 μmol / m 2 The results show that the range of PPFD is appropriate for 2 μmol / m 2 There is a tendency that the distribution of plot points showing higher SPAD values ​​increases as the value approaches / s. The appropriate value of the SPAD value is shown in Figure 3, where PPFD is 0 μmol / m 2 The SPAD value (15.4) for a short-term treatment of 1000 / s was used as a reference. In this case, the leaf color was green, which is at the lower limit of the acceptable range, as shown in Figure 4.

[0055] As described above, from Figs. 10 and 11, in the refrigeration process of step S2 where the refrigeration temperature is 2.4 to 4.1°C, the PPFD where the SPAD value is the appropriate value is 2 to 20 μmol / m 2 / s, and in this case too, the results showed that the growth of seedlings was stably maintained and the occurrence of photoinhibition was prevented.

[0056] It should be noted that the refrigerated seedling growing method of field wasabi according to the present invention is not limited to those shown in the Examples. For example, in the refrigeration device 2 used to implement the growing methods 1 and 1A, the light source 5 may be disposed to the side of the seedling 10 instead of above the seedling 10. [Industrial Applicability]

[0057] The present invention can be used as a method for growing refrigerated field wasabi seedlings, in which field wasabi seedlings are refrigerated under specified conditions to grow refrigerated field wasabi seedlings. [Explanation of symbols]

[0058] 1,1A...Growth method 2...Refrigeration device 3...Refrigerator 4...Shelf 4A...Shelf board 4a...Top surface 4b...Bottom surface 5...Light source 6...128-hole cell tray 7...Bottom water supply tray 8...Cultivation surface 10...Seedling

Claims

1. The method for growing refrigerated seedlings of field wasabi comprises a refrigeration step of refrigerating field wasabi seedlings at a refrigeration temperature of 2 to 5°C for a certain period of time to produce the refrigerated seedlings of field wasabi.

2. The refrigeration step includes irradiating the seedlings of the field wasabi with light, The light has a photosynthetic photon flux density of 2 to 30 μmol / m on the cultivation surface without the seedlings. ２ 2. The method for growing refrigerated seedlings of field wasabi according to claim 1, wherein the temperature is 100° C. / s.

3. The method for growing refrigerated field wasabi seedlings according to claim 1 or 2, characterized in that the certain period is 5 to 6 months.

4. A growing step of planting and growing the refrigerated seedlings of the field wasabi in a field after the refrigeration step, 3. The method for growing refrigerated field wasabi seedlings according to claim 1 or 2, characterized in that the planting is carried out during a period when the maximum temperature in the field is 25° C. or lower.

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