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 growing method for growing wasabi seedlings, and particularly relates to a method for growing refrigerated wasabi seedlings by refrigerating young wasabi seedlings under predetermined conditions to grow refrigerated wasabi seedlings.

Background Art

[0002] Conventionally, wasabi seedlings wither when the temperature exceeds about 25°C, so it is difficult to raise seedlings in summer. And this point is one of the reasons why the yield of wasabi does not increase. Note that even for the same species of wasabi, depending on the cultivation method, it is called field wasabi or water wasabi. The former is cultivated in a general field and the petioles and leaf blades are harvested. The latter is cultivated in a wasabi field using a stream or spring water, and the rhizome is harvested. Therefore, in the case of field wasabi, as a conventional cultivation method, young field wasabi seedlings are raised in a forest field in a cool highland for about one year, and then the raised seedlings are planted in a field in a pipe house with shading, and further grown until they become mature plants of a harvestable size for about 7 to 8 months. Such a method has been adopted. However, the above cultivation method has a problem that the period from young seedlings to mature plants becomes about 20 months, which is a long period. Furthermore, since it is necessary to carry young field wasabi seedlings up to the highland and lower them into the pipe house, there is also a problem that the labor and cost burden is large. Therefore, in recent years, technologies that can reduce such a burden have been developed, and inventions related thereto have already been disclosed.

[0003] Patent Document 1 discloses an invention related to a method for growing wasabi seedlings in an artificial environment under the name of "Method for Growing Wasabi Seedlings". The invention disclosed in Patent Document 1 will be described below. The invention disclosed in Patent Document 1 supplies water which may contain nutrient solution and light to a growth medium in an artificial facility maintained at 18 to 20°C, while sowing Japanese horseradish seeds in which cotyledons are stored inside the seed coat and hairy lateral roots have emerged on a 3- to 7-mm radicle, and growing the seeds until germination and the cotyledons unfold, and then growing them until 4 to 6 true leaves unfold in place of the cotyledons. It is a method for growing Japanese horseradish seedlings, characterized by this. In an invention having such characteristics, in order to grow Japanese horseradish seedlings in an artificial facility, by providing this artificial facility near a Japanese horseradish field or the like, it is considered possible to grow Japanese horseradish seedlings throughout the year and also reduce transportation costs. In addition, since the Japanese horseradish field can maintain an environment around 20°C due to spring water or the like, even if the planting time is July, the survival rate of Japanese horseradish seedlings can be made about 100%.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the invention disclosed in Patent Document 1, it is unclear whether it can be adapted to field Japanese horseradish. Furthermore, there is no description regarding whether the growth period from a seedling to a mature plant of a size that can be sufficiently harvested, for example, has been shortened by the grown Japanese horseradish seedlings. Therefore, it is unclear whether the problem of lengthening the period until it becomes a mature plant can be sufficiently solved by the invention disclosed in Patent Document 1. In addition, regarding the invention disclosed in Patent Document 1, even when the planting time is July and the survival rate of wasabi seedlings is about 100%, there is no description as to whether it is possible to prevent withering due to high temperatures after planting. Therefore, it is also unclear whether the problem that the yield of wasabi does not increase due to high temperatures can be sufficiently solved by the invention disclosed in Patent Document 1.

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

Means for Solving the Problems

[0007] To achieve the above object, a first invention is characterized by comprising a refrigeration step of refrigerating seedlings of field wasabi at a refrigeration temperature of 2 to 5°C for a certain period to produce refrigerated seedlings of field wasabi. In the invention having such a configuration, the seedling is a seedling that has reached a predetermined growth state, for example, a seedling in which the true leaves have reached a certain number or area. However, in addition to this, the predetermined growth state can be arbitrarily defined. In addition, the method for raising seedlings until seeds of field wasabi are sown in a growth medium and germinated and the germinated seeds are raised into seedlings is not particularly limited. Furthermore, in this step, artificial light may or may not be irradiated on the seedlings of field wasabi. In the present application, the seedling and the mature plant are terms used with a focus on the degree of growth of the wasabi seedling, and the refrigerated seedling is a term used with a focus on the state in which the seedling is refrigerated in the refrigeration step.

[0008] In the invention with the above configuration, it is considered that by refrigerating the seedlings of Wasabi japonica at a refrigeration temperature of 2 to 5°C for a certain period, dormancy is introduced into the seedlings, and then dormancy is broken. The refrigeration is performed, for example, by storing the seedlings in a refrigerator. The certain period is adjusted according to the outside air temperature so that, for example, the seedlings can be prevented from withering at high temperatures, or the cost of artificial refrigeration for the seedlings before the refrigeration process can be suppressed. When the seedlings in which dormancy has been broken, that is, the refrigerated seedlings, are planted in the field, the refrigerated seedlings start to grow rapidly.

[0009] The second invention is, in the first invention, the refrigeration process is such that light is irradiated on the seedlings of Wasabi japonica, and the photosynthetic photon flux density on the cultivation surface in a state without seedlings is 2 to 30 μmol / m 2 / s. In the invention with such a configuration, as a light source for the light, for example, an LED lamp for plant growth is preferably used.

[0010] In the invention with the above configuration, in addition to the action of the first invention, by setting the photosynthetic photon flux density to 2 μmol / m 2 / s or more, the growth of the seedlings at a refrigeration temperature of 2 to 5°C is stably maintained. Also, by setting the photosynthetic photon flux density to 30 μmol / m 2 / s or less, the occurrence of photo-inhibition at the same refrigeration temperature is prevented.

[0011] Subsequently, the third invention is, in the first or second invention, the certain period is 5 to 6 months. In the invention with such a configuration, in addition to the action of the first or second invention, since the certain period of refrigeration is 5 to 6 months, the high temperature period (for example, the latter half of spring to summer) that is unsuitable for the growth of Wasabi japonica can all be utilized as the dormancy period of the seedlings.

[0012] Furthermore, the fourth invention is characterized in that, in the first or second invention, after the refrigeration step, there is a growth step of planting and growing the refrigerated seedlings of wasabi in the field, and the planting is carried out when the maximum temperature in the field becomes 25 °C or lower.

[0013] In the invention having such a configuration, in addition to the action of the first or second invention, since the planting is carried out when the maximum temperature in the field becomes 25 °C or lower, the death of the refrigerated seedlings due to high temperature after planting is avoided.

Effect of the Invention

[0014] According to the first invention, by providing the refrigeration step, the refrigerated seedlings start rapid growth, so it can be expected that the seedlings will grow into mature plants in a short period. In addition, when the seedlings are stored in a refrigerator, there is no need to carry the wasabi seedlings to high altitudes or lower them into a pipe house, and the problems of labor and cost burden can be completely solved.

[0015] According to the second invention, in addition to the effect of the first invention, by setting the photosynthetic photon flux density to 2 to 30 μmol / m 2 / s, the growth of the seedlings at a refrigeration temperature of 2 to 5 °C is stably maintained and the occurrence of photo-inhibition is prevented. Therefore, the number of missing plants can be suppressed to a small number, and the seedlings can be grown uniformly.

[0016] According to the third invention, in addition to the effect of the first or second invention, since all the high-temperature periods unsuitable for the growth of wasabi can be utilized as the dormant periods of the seedlings, the high-temperature periods, which were a major problem in the past in preventing the death of the seedlings, can be converted into preparation periods for the seedlings to start rapid growth and can be actively and effectively utilized. Also, if the refrigeration step is started, for example, in spring, since the outside air temperature before the refrigeration step (specifically, the period from sowing to raising the seedlings into seedlings) is usually lower than about 25 °C, it is not always necessary to artificially refrigerate the seeds or seedlings before the refrigeration step. As a result, the seedlings can be raised at low cost before the refrigeration step.

[0017] According to the fourth invention, in addition to the effects of the first or second invention, since the death of seedlings due to high temperature after planting is avoided, it is possible to solve the conventional problem that the yield of field wasabi does not increase.

Brief Description of the Drawings

[0018]

Figure 1

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Figure 11

Mode for Carrying Out the Invention

Example

[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 FIGS. 1 to 9. FIG. 1 is a process diagram of the method for growing refrigerated seedlings of field wasabi according to Example 1. As shown in FIG. 1, the method for growing refrigerated seedlings of field wasabi according to Example 1 (hereinafter referred to as the growing method) 1 includes a germination and seedling stage in step S1, a refrigeration stage in step S2, and a growth stage in step S3. Hereinafter, each stage will be described in order.

[0020] First, the germination and seedling stage in step S1 is a stage of germinating the seeds of field wasabi and creating seedlings 10 (see FIG. 2). In this stage, first, the seeds are immersed in an aqueous solution containing 100 ppm of gibberellin by weight, and then the immersed seeds are sown in a seedling medium formed in, for example, a cell tray, and maintained in a pipe house (around March to April) with a maximum air temperature of 25°C or lower. Thereby, germinated seeds of field wasabi are obtained.

[0021] Then, the germinated seeds are grown until they become seedlings 10 in a predetermined growth state. Also, in this stage, the predetermined growth state can be defined, for example, as a state where the seedlings have grown until two true leaves have developed. However, as long as seedlings 10 in a certain growth state are obtained, other definitions may be adopted. Note that this stage is a known stage.

[0022] Subsequently, the refrigeration stage in step S2 is a stage of accommodating the seedlings 10 of field wasabi grown in the germination and seedling stage in step S1 in a refrigerator 3, maintaining the refrigeration temperature at 2 to 5°C, and refrigerating for a certain period to create refrigerated seedlings of field wasabi. Also, during refrigeration, the grown seedlings 10 of field wasabi are irradiated with light.

[0023] Next, the refrigeration device used in the implementation of the cultivation 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 process that constitutes the refrigerated seedling cultivation method of field wasabi according to Example 1. As shown in FIG. 2, the refrigeration device 2 includes a refrigerator 3, a shelf 4 having a multi-stage shelf board 4A accommodated in the refrigerator 3, and a light source 5 installed on each of the shelf boards 4A. In addition, the young seedlings 10 of field wasabi created in the germination step of step S1 are cultivated in the seedling cultivation medium of a 128-hole cell tray 6 and placed on the upper surface 4a of the shelf board 4A. Specifically, the young seedlings 10 and the 128-hole cell tray 6 are accommodated inside a box-shaped bottom water supply tray 7 placed on the upper surface 4a. Furthermore, on the lower surface 4b of the shelf 4, a light source 5 for irradiating light on the young seedlings 10 from above is installed. Specifically, this light source 5 is a plant-growing LED lamp that emits light with a wavelength of about 400 to 800 nm.

[0024] And the light irradiated on the young seedlings 10 has a photosynthetic photon flux density (hereinafter referred to as PPFD) on the cultivation surface 8 of the seedling cultivation medium in a state where there are no young seedlings 10 of 5 to 30 μmol / m 2 / s. Also, the light source 5 is controlled by a control unit (not shown) having a timer function to repeat lighting and extinguishing, for example, every 12 hours. Furthermore, the fixed period of refrigeration is 5 to 6 months.

[0025] And the growth step of step S3 is a step of planting the refrigerated seedlings of field wasabi created in the refrigeration step of step S2 in the field and growing them until they become mature plants of a harvestable size. By this step, mature plants can actually be obtained in a short growth period. Here, the field, unlike the aforementioned wasabi field, refers to agricultural land that does not have the function of retaining water. Also, this planting is carried out when the maximum temperature in the field is 25°C or lower. Furthermore, in this step, the growth period from planting to harvesting is, for example, about 5 months. Therefore, in cultivation method 1, when the total duration of the refrigeration process in step S2 (5 - 6 months) and the growth period of the growth process in step S3 (about 5 months) are added together, it amounts to approximately 10 - 11 months. Thus, in cultivation method 1, compared with the case where the period from young seedlings to mature plants is about 20 months in the conventional cultivation method, mature plants can be harvested in approximately half the time.

[0026] Next, the influence of the light intensity irradiated during refrigeration on the quality of wasabi seedlings will be explained with reference to FIGS. 3 and 4. FIG. 3 is a table showing the influence of light intensity on the refrigerated wasabi seedlings created by the refrigerated wasabi seedling cultivation method according to Example 1. FIG. 4 is an image of the refrigerated wasabi seedlings when irradiated with light of different light intensities in the refrigeration process. FIG. 3 shows the case where the refrigeration temperature in the refrigeration process of step S2 is 5°C, and the PPFD of the light emitted by the light source 5 is changed to 0, 30, 60, 90 μmol / m 2 / s for each section. The measured values of the plant height (cm), number of leaves (pieces), SPAD (leaf chlorophyll meter) value, above-ground dry matter weight (g), and below-ground dry matter weight (g) of the refrigerated seedlings are respectively measured. Note that these measured values are all average values for 8 refrigerated seedlings.

[0027] Here, among the measured values shown in FIG. 3, the SPAD values for 0, 30, 60, 90 μmol / m 2 / s are 15.4, 19.5, 9.3, 8.8 respectively. That is, the SPAD values at PPFD of 60, 90 μmol / m 2 / s are about half of the SPAD values at PPFD of 0, 30 μmol / m 2 / s. The reason for such a result is considered to be that when the PPFD exceeds 30 μmol / m 2 / s, the light energy becomes excessive and photo-inhibition is caused. Therefore, in the refrigeration process of step S2, it is found that at a refrigeration temperature of 5°C, it is desirable that the PPFD does not exceed 30 μmol / m 2 / s.

[0028] Next, FIG. 4 is an image of the refrigerated seedlings of field wasabi when the PPFD is changed at a refrigeration temperature of 5°C. In the figure, 0, 30, 60, and 90 are the PPFD of the light emitted by the light source 5. Also, along the direction of the arrow in the figure, the seedlings divided and arranged into four sections respectively are the refrigerated seedlings of each section. As shown in FIG. 4, the leaf color, which is green (dark gray in the figure), is the darkest when the PPFD is 30 μmol / m 2 / s, and then becomes lighter in the order of 0, 60, 90 μmol / m 2 / s. Also, when the PPFD is 60, 90 μmol / m 2 / s, the number of leaves that have changed to yellow (off-white in the figure) is clearly increasing compared to the case of 30 μmol / m 2 / s.

[0029] Also, regarding the magnitude of the PPFD, the trend of the green color intensity and the trend of the number of discolored leaves are respectively consistent with the trend of the magnitude of the SPAD value shown in FIG. 3. Therefore, it is considered that the occurrence of photo-inhibition can also be recognized visually. Therefore, as is clear from the SPAD value shown in FIG. 3, at a refrigeration temperature of 5°C, it is desirable that the PPFD does not exceed 30 μmol / m 2 / s. This finding was also visually confirmed by the image of the refrigerated seedlings.

[0030] Next, regarding the quality of the refrigerated seedlings during the refrigeration process, it will be described in detail with reference to FIG. 5. FIGS. 5(a) to 5(d) are graphs showing the quality of the refrigerated seedlings of field wasabi created by the method for growing refrigerated seedlings of field wasabi according to Example 1. Specifically, FIGS. 5(a) to 5(d) respectively show the temporal changes in the quality of the seedlings 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, 10 μmol / m 2 / s. Hereinafter, FIGS. 5(a) to 5(d) will be described in order.

[0031] First, in Fig. 5(a), the vertical axis represents the above-ground part (petiole and leaf blade) dry weight (g) of the cold-stored seedlings, and the horizontal axis represents the measurement date (month / day) of the dry weight. Also, in all of Figs. 5(a) to 5(d), among the measurement dates, February 25th (2 / 25) is the cold storage start date. As shown in Fig. 5(a), as the cold storage period elapsed, the above-ground dry weight decreased from the cold storage start date when the PPFD was 0 μmol / m 2 / s, and remained almost the same when the PPFD was 2 μmol / m 2 / s. In contrast, when the PPFD was 5, 10 μmol / m 2 / s, the above-ground dry weight increased from the cold storage start date in all cases. This increase amount became larger as the PPFD increased.

[0032] Next, in Fig. 5(b), the vertical axis represents the below-ground part (root) dry weight (g) of the cold-stored seedlings, and the horizontal axis represents the measurement date (month / day) of the dry weight. As shown in Fig. 5(b), as the cold storage period elapsed, the below-ground dry weight decreased from the cold storage start date when the PPFD was 0, 2 μmol / m 2 / s respectively, and remained almost the same when the PPFD was 5 μmol / m 2 / s. In contrast, when the PPFD was 10 μmol / m 2 / s, the below-ground dry weight increased from the cold storage start date.

[0033] Furthermore, in Fig. 5(c), the vertical axis represents the plant height (cm) of the cold-stored seedlings, and the horizontal axis represents the measurement date (month / day) of the plant height. As shown in Fig. 5(c), as the cold storage period elapsed, the plant height became shorter than the cold storage start date when the PPFD was 0 μmol / m 2 / s, and became longer than the cold storage start date in all cases when the PPFD was 2, 5, 10 μmol / m 2 / s.

[0034] And in Fig. 5(d), the vertical axis represents the number of expanded leaves (pieces) of the cold-stored seedlings, and the horizontal axis represents the measurement date (month / day) of the number of expanded leaves. As shown in Fig. 5(d), as the cold storage period elapsed, the number of expanded leaves decreased when the PPFD was 0 μmol / m 2In the case of / s, it decreased from the cold storage start date, to 2 μmol / m 2 In the case of / s, it was almost maintained. In contrast, when the PPFD was 5, 10 μmol / m 2 / s, the number of live leaves in both cases increased from the cold storage start date.

[0035] As described above, from FIGS. 3, 4 and 5(a) to 5(d), in the cold storage process of step S2 where the cold storage temperature is 2 to 5°C, as the cold storage period elapses, the PPFD at which the above-ground dry matter weight, underground dry matter weight, plant height and 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 / s. Therefore, in the cold storage process of step S2 where the cold storage temperature is 2 to 5°C, in the case of 5 to 30 μmol / m 2 / s, it was possible to obtain the result that the growth of the seedlings was stably maintained and the occurrence of photo-inhibition was prevented.

[0036] Subsequently, the growth status of the cold-stored seedlings after transplantation will be described in detail with reference to FIG. 6. FIG. 6 is a graph showing the growth status of the cold-stored seedlings of field wasabi during the growth process according to Example 1, where the vertical axis represents the plant height (cm) of the cold-stored seedlings and the horizontal axis represents the measurement date (month / day) of the plant height. Among the measurement dates, October 12 (10 / 12) is the transplantation date. The transplantation month was set to October because the outside air temperature in the field becomes 25°C or lower. Furthermore, FIG. 6 shows the temporal change in the plant height of the cold-stored seedlings after transplantation in the growth process of step S3 when the month in which the seeds of field wasabi were sown in the seedling cultivation medium in the germination process of step S1 was March, April, or May.

[0037] In addition, as a comparative example, the time change in the plant height of seedlings of field-grown Japanese horseradish cultivated by the conventional cultivation method (hereinafter referred to as "conventional seedlings") is also shown. The cultivation method of these conventional seedlings is as follows: Seeds of Japanese horseradish germinated by the same method as in the germination step of Step S1 are sown in a seedling medium in April to obtain seedlings, and then these seedlings are transferred to a cool highland as described above and raised in an artificial horseradish field, and further, the raised seedlings are planted in the field in October. Note that these plant heights are average values for 10 plants in 3 replicates for both the refrigerated seedlings and the conventional seedlings.

[0038] As shown in FIG. 6, in the plant height during the growth step of Step S3, regardless of whether the month when the seeds are sown in the seedling medium is March, April, or May, there is no phenomenon of temporarily shortening immediately after planting. This is considered to be because in the refrigerated seedlings, the roots are maintained or well formed (refer to 5 and 10 μmol / m 2 / s in FIG. 5(b)), so the leaves are less likely to wither after planting, and the growth rate of the newly growing true leaves is also faster. Therefore, the plant height becomes approximately the same length as about 20 cm about 1 month after planting (November 14), and grows to a length of about 60 cm about 5 months after planting (March 8). And the plant height is still about 60 cm even about 6 months after planting (April 10). Since there is no change seen from about 5 months after planting, it is recognized that the peak of the plant height is about 5 months after planting. Therefore, in Cultivation Method 1, when the refrigerated seedlings are planted in October, it is possible to harvest mature plants in early March of the following year.

[0039] On the other hand, in the case of the conventional seedlings according to the comparative example, the plant height temporarily decreased to about 10 cm about 1 month after planting. This is considered to be because, unlike the refrigerated seedlings, the roots of the conventional seedlings are not well formed, so the leaves wither after planting and the growth rate of the newly growing true leaves is slow. After that, the plant height increased with a slope almost the same as that of the refrigerated seedlings in Cultivation Method 1, about one month later than the refrigerated seedlings, and it was recognized that the peak was reached about six months after planting. Thus, in the conventional cultivation method, when the young seedlings are planted in October, the harvest of mature plants will be at least after April of the following year. Therefore, Cultivation Method 1 is highly effective against the conventional cultivation method in terms of enabling early harvesting.

[0040] In addition, the plant height at the peak of the conventional seedlings (about 55 cm) is shorter than that of the refrigerated seedlings at the peak (about 62 cm). Therefore, results were obtained suggesting that Cultivation Method 1 is also highly effective against the conventional cultivation method in terms of the harvest quantity and the appearance of mature plants.

[0041] Next, the growth status of the refrigerated seedlings after planting in the field will be described. FIGS. 7 and 8 are images showing the growth status of the refrigerated seedlings of wasabi in the field during the growth process according to Example 1, respectively. FIG. 7 is an image taken on January 12 of the following year, three months after planting, of the refrigerated seedlings whose plant height change over time was shown in FIG. 6 and the conventional seedlings. Note that both the refrigerated seedlings and the conventional seedlings were sown on April 8 and planted on October 12. Also, the refrigeration start date of the refrigerated seedlings is May 15. As shown in FIG. 7, when comparing the appearance of the refrigerated seedlings and the conventional seedlings, for example, in terms of both plant height and leaf area, the refrigerated seedlings grew significantly larger than the conventional seedlings.

[0042] Also, FIG. 8 is an image taken on February 9, one month later, of the refrigerated seedlings and the conventional seedlings shown in FIG. 7, and it can be seen that the growth difference between the refrigerated seedlings and the conventional seedlings confirmed in FIG. 7 is maintained. Thus, in terms of the harvest quantity and the appearance of mature plants, it was visually confirmed by the images of the refrigerated seedlings that Cultivation Method 1 is highly effective against the conventional cultivation method.

[0043] Furthermore, the harvest of mature plants by cultivation method 1 will be described with reference to FIG. 9. FIG. 9 is a table showing the harvest of mature perilla plants at the completion of the growth process according to Example 1. As shown in FIG. 9, in cultivation method 1, for the months of March, April, and May when the seeds were sown, the harvest of mature plants per 10 ares was 3,464 - 3,900 kg for the above-ground part (processed weight), and 4,213 - 5,546 kg for the whole plant (above-ground part + underground part, processed weight).

[0044] In contrast, for the conventional seedlings, the above-ground part (processed weight) was 1,615 kg, and the whole plant (processed weight) was 2,423 kg. That is, the harvest of mature plants of the refrigerated seedlings by cultivation method 1 was about 2.1 - 2.4 times that of the above-ground part and 1.7 - 2.3 times that of the whole plant compared to the harvest of the conventional seedlings. Therefore, it was clarified that cultivation method 1 is extremely effective compared to the conventional cultivation method in terms of harvest. Note that the measurement date of the harvest was March 8th for both cultivation method 1 and the conventional cultivation method.

[0045] As described above, the peak of the plant height in the growth process of step S3 was recognized about 5 months after transplantation regardless of the sowing month, while the peak of the plant height by the conventional cultivation method was about 6 months after transplantation. This result demonstrates that the refrigerated seedlings that have broken dormancy start rapid growth and grow from seedlings to mature plants in a short period by including the refrigeration process in step S2.

[0046] In addition, since the refrigeration process in step S2 is a simple process of storing the perilla seedlings 10 in the refrigerator 3 and setting the refrigeration temperature and PPFD within appropriate ranges, the operation of transporting the perilla seedlings according to the time and growth state becomes unnecessary, and the influence of extremely high abnormal temperatures, which has been remarkable in recent years, can also be eliminated. Therefore, according to cultivation method 1, by including the refrigeration process in step S2, the conventional problem of a large burden of labor and cost can be completely solved, and it becomes possible to ensure the harvest of mature perilla plants without being affected by climate change.

[0047] Furthermore, in Cultivation Method 1, when cold-stored seedlings are planted in October, mature plants can be harvested in early March of the following year. Therefore, compared with the conventional cultivation method where the harvest is at least after April of the following year, the damage caused by pests and diseases is less. Thus, according to Cultivation Method 1, mature plants with excellent appearance and high commodity value can be obtained, and the labor for shipment preparation can also be reduced.

[0048] In addition, the yield of mature plants was about 2.1 - 2.4 times that of the above-ground part and 1.7 - 2.3 times that of the round digging compared to the yield of the conventional cultivation method. This result demonstrates that the yield of field wasabi can be increased by including the cold storage step in Step S2.

Example

[0049] The cold-stored seedling cultivation method for field wasabi according to the second embodiment of the present invention will be described in detail with reference to FIGS. 10 and 11. The upper part of FIG. 10 is the PPFD of the light irradiated in the cold storage step constituting the cold-stored seedling cultivation method for field wasabi according to Example 2, and the lower part is an image of the cold-stored seedlings of field wasabi corresponding to the PPFD in the upper part. First, the steps of Cultivation Method 1A for cold-stored seedlings of field wasabi according to Example 2 (hereinafter referred to as "cultivation method") will be described. Cultivation Method 1A includes a germination and seedling stage in Step S1, a cold storage stage in Step S2, and a growth stage in Step S3, similar to Cultivation Method 1 according to Example 1.

[0050] However, in Cultivation Method 1A, among the above steps, in the cold storage step of Step S2, the minimum value of the PPFD of the light on the cultivation surface 8 (see FIG. 2) of the seedling cultivation medium in the state where there are no seedlings 10 is different from the minimum value of the PPFD in Cultivation Method 1 according to Example 1. However, the germination conditions and seedling raising conditions in the germination and seedling stage of Step S1, the growth conditions in the growth stage of Step S3, and the cold storage device 2, light source 5, etc. used in Cultivation Method 1A are all the same as those in the case of Cultivation Method 1.

[0051] Next, each numerical value in the upper part of FIG. 10 is the PPFD of the light irradiated on the refrigerated seedlings in the refrigeration step of step S2 of the growth method 1A. The refrigeration temperature is 2.4 to 4.1 ° C (average 3.1 ° C in the refrigerator 3). As shown in the upper part of FIG. 10, the range of the PPFD of the light for a plurality of refrigerated seedlings arranged separately in four sections is, in order from the left, (1) 8.5 to 19, (2) 3.2 to 14.1, (3) 16.9 to 37.2, (4) 15.6 to 78.7 μmol / m 2 / s.

[0052] Furthermore, as shown in the lower part of FIG. 10, in all cases where the PPFD is (1) to (4), the refrigerated seedlings maintain the growth of the young seedlings and show the same degree of growth. In addition, the leaf color of the refrigerated seedlings is green (dark gray in the figure) when the PPFD is (1) or (2). On the other hand, when the PPFD is (3) or (4), the leaf color of the refrigerated seedlings changes from white to yellow (from white to off-white in the figure). From this result, it is considered that photo-inhibition occurred in the refrigerated seedlings when the PPFD was (3) or (4). Furthermore, as shown in FIGS. 3 and 4, since the tendency of the greenness represents the tendency of the magnitude of the SPAD value, it is considered that by obtaining the correlation between the PPFD and the SPAD value, the range of the PPFD that can obtain an appropriate SPAD value can be determined.

[0053] Therefore, the correlation between the PPFD and the SPAD value of the refrigerated seedlings will be described with reference to FIG. 11. FIG. 11 is a scatter diagram in which points corresponding to the PPFD of the light irradiated in the refrigeration step constituting the method for growing refrigerated seedlings of field wasabi according to Example 2 and the SPAD value of the refrigerated seedlings are plotted. The vertical axis represents the SPAD value, and the horizontal axis represents the PPFD of the light (μmol / m 2 / s).

[0054] As shown in FIG. 11, the SPAD value is represented by a regression line for the PPFD (the dotted line in the figure, coefficient of determination 0.3992). This regression line shows that there is a negative correlation that the SPAD value decreases as the PPFD increases. Therefore, when the appropriate value of the SPAD value is set to 15 or more, from this regression line, it is obtained that the appropriate range of PPFD is 2 to 20 μmol / m 2 / s. Specifically, as PPFD approaches 2 μmol / m 2 / s, a tendency is recognized that the distribution of plot points showing higher SPAD values increases. The appropriate value of the above-mentioned SPAD value is based on the SPAD value (15.4) in the short-term treatment with PPFD of 0 μmol / m 2 / s shown in FIG. 3. In this case, as shown in FIG. 4, the leaf color is green at the lower limit of the allowable range.

[0055] As described above, from FIGS. 10 and 11, in the refrigeration step of step S2 where the refrigeration temperature is 2.4 to 4.1 °C, the PPFD at which the SPAD value becomes an appropriate value is 2 to 20 μmol / m 2 / s. Also in this case, it was possible to obtain the result that the growth of the seedlings was stably maintained and the occurrence of photo-inhibition was prevented.

[0056] Note that the method for growing refrigerated seedlings of field wasabi according to the present invention is not limited to that shown in the examples. For example, in the refrigeration device 2 used for carrying out the growing methods 1 and 1A, the light source 5 may be arranged on the side of the seedlings 10 instead of being arranged above the seedlings 10.

Industrial Applicability

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

Explanation of Signs

[0058] 1, 1A... growing methods 2... refrigeration device 3... refrigerator 4... shelf 4A... shelf board 4a... upper surface 4b... lower surface 5... light source 6... 128-hole cell tray 7... bottom water supply tray 8... cultivation surface 10... seedlings

Claims

1. A refrigeration process for creating a refrigerated seedling of field wasabi by refrigerating the seedlings of field wasabi at a refrigeration temperature of 2 to 5°C for a certain period, wherein, in the refrigeration process, light is irradiated on the seedlings of the field wasabi, and the light is characterized in that the photosynthetic photon flux density on the cultivation surface in a state without the seedlings is 2 to 30 μmol / m2 / s. A method for growing refrigerated seedlings of field wasabi.

2. The method for growing refrigerated seedlings of field wasabi according to Claim 1, wherein the certain period is 5 to 6 months.

3. After the refrigeration process, a growth process for planting and growing the refrigerated seedlings of the field wasabi in the field is provided, wherein the planting is carried out at a time when the maximum temperature in the field is 25°C or lower. The method for growing refrigerated seedlings of field wasabi according to Claim 1 or Claim 2.

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