JP2017221177A - Method of producing vegetables fortified with various antioxidant components by hydroponic cultivation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of producing vegetables remarkably fortified with various antioxidant components by hydroponic cultivation.SOLUTION: This method of producing vegetables fortified with various antioxidant components by hydroponic cultivation secures metabolic pathways mainly for the biosynthesis of antioxidant components by using nutrient solution substantially not including nitrogen for a fixed period prior to harvesting, and promotes the induction of antioxidant components by adjusting the conditions for lighting and/or the nutrient solution. Furthermore, the vegetables are cultivated for a fixed period prior to harvesting using a nutrient solution substantially not including nitrogen but including calcium and irradiating with light including visible light of a wavelength of 490 nm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing vegetables by hydroponics, and more particularly, to a method for producing vegetables by hydroponics for the purpose of enhancing various antioxidant components.

Hydroponics is expected as an alternative to conventional soil cultivation.
Hydroponics is easy to manage without problems such as continuous cropping problems.
It is also easy to increase the yield of plants by increasing the speed of plant growth.
Furthermore, by optimizing nutrient solution components and lighting conditions, it is possible to produce agricultural products with enhanced nutritional value and functional agricultural products.

  For example, for the grown vegetables, the nutrient solution is replaced with water just before harvesting, the day length is set to 17 hours or more, and the upper limit of the light intensity in the day length is set to 20000 lux. An adjusted cultivation method that can increase the content of useful components such as ascorbic acid content, sugar content, and total sugar content and reduce the nitrate ion content has been proposed (for example, Patent Document 1). ).

  In addition, it is proposed to reduce the concentration of nitrate nitrogen in plants by moving the plants to another cultivation tray before harvesting, absorbing water, or irradiating light with strong illuminance. (For example, Patent Document 2).

  Furthermore, in order to improve the taste of parsley, a cultivation method has been proposed in which light is mainly composed of red during the growing season and light is composed mainly of blue before harvesting after the growth. (For example, patent document 3).

JP2015-192682A JP2013-123403A JP2013-162757A

  In the invention disclosed in Patent Document 1, the ascorbic acid content is increased from 1.7 times to about 3 times that of the control group, but various antioxidant components are not increased. Moreover, it is necessary to irradiate intense light for a long time, and there is a concern about an increase in production cost.

In the invention disclosed in Patent Document 2, nitrate nitrogen can be reduced, but various antioxidant components cannot be greatly increased.
Furthermore, in the invention disclosed in Patent Document 3, it is possible to improve the taste of parsley, but the antioxidant component cannot be increased greatly.

  The present invention has been made in order to solve the above-described problems, and provides a method for producing vegetables in which various antioxidant components are remarkably enhanced. More specifically, the aim is to increase the amount of biosynthesis of antioxidant components by changing the flow of carbon metabolism fixed by photosynthesis to the flow of biosynthesis of antioxidant components. It is a thing. Moreover, the energy cost of irradiation light is reduced by irradiating the light of the wavelength suitable for enhancing the biosynthesis amount of the antioxidant component.

The method for producing vegetables with enhanced various antioxidant components by hydroponics according to the present invention,
In a certain period before harvest,
By using a nutrient solution that does not substantially contain nitrogen, a metabolic pathway mainly consisting of biosynthesis of antioxidant components is secured,
It is characterized by promoting the induction of antioxidant components by adjusting light irradiation conditions and / or nutrient solution conditions.
In addition, a method for producing vegetables with enhanced various antioxidant components by hydroponics according to the present invention,
Using nutrient solution that does not contain nitrogen and contains calcium,
By irradiating light including visible light of 490 nm or less,
It is characterized by growing vegetables for a certain period before harvesting.

  The method for producing vegetables by hydroponics according to the present invention enables the production of vegetables with significantly enhanced various antioxidant components, contributes to the health promotion of those who eat it, aging, cancer, heart disease, It can be expected to improve the preventive effect against many diseases such as stroke and diabetes. It also has the effect of reducing the nitrate nitrogen content.

It is a figure for demonstrating the effect of this invention, (a) is a metabolic image in case a nutrient solution contains nitrogen, (b) is a metabolic image in case a nutrient solution does not contain nitrogen.

  The details of the method for producing vegetables by hydroponics according to the present invention and the results of experiments conducted to confirm the new efficacy will be described below. The following description discloses a good example relating to the present invention, and the present invention is not limited to the embodiment.

  The production method of the present invention can be applied to various vegetables, and particularly has a remarkable effect on leafy vegetables. Other vegetables have similar effects, albeit with varying degrees.

<Features of production method>
The feature of the production method of the present invention is that the nutrient solution components and irradiation light conditions are changed between the vegetable growing season and before harvesting.
Here, the growth period is a period until the leaves are fully developed after transplanting the germinated seedlings. However, the present invention is not limited to this period. For example, in the case of early harvesting such as baby leaves, the growth period means up to several days before harvesting.
In several days before harvesting, for example, from 1st to 5th before harvesting, cultivation is performed under conditions different from the growth period as pre-harvest treatment.

<Example of cultivation conditions in the growing season>
Regarding the nutrient solution and light irradiation conditions during the growth period, no special conditions are required, and a general nutrient solution may be used and light may be irradiated under the general irradiation conditions.
For example, regarding nutrient solution, Otsuka House No. 1, No. 2, No. 5 may be used, and trace minerals may be added. A specific example of nutrient solution during the growth period is shown below.

The nutrient solution is divided into two tanks, each diluted with water and mixed for use.

Tank 1
Otsuka House 1 80g / l
Otsuka House 5 5g / l
EDTA-Fe (Na) 5g / l

Tank 2
Otsuka House 2 140g / 0.98l

The above is a nutrient solution suitable for spinach, salad vegetables, nitrite vegetables such as Komatsuna and Japanese radish. In the case of an ammoniaphilic vegetable such as lettuce, seri, and strawberry, ammonium sulfate may be added to the tank 1.
In any case, regarding the nutrient solution in the growth period, a nutrient solution configuration suitable for growing the cultivated vegetables may be used.

  In addition, for the purpose of increasing the content of useful minerals such as potassium, zinc, and iron in vegetables, these components may be added in a small amount to the nutrient solution.

<Pre-harvest treatment>
Next, the pre-harvest process will be described. As described above, the pre-harvest process is preferably performed for 1 to 5 days before the harvest. This period is appropriately determined depending on the type of vegetable.
There are three points that are particularly important as pre-harvest treatment, and the first is to make the nitrogen component almost zero. It removes not only nitrate nitrogen but also ammonia nitrogen. Therefore, it is necessary to completely replace the nutrient solution. After completely removing the nutrient solution used in the growth period from the planter, the nutrient solution used for pre-harvest treatment is introduced into the planter. As for whether the nutrient solution used in the growth period does not remain in the planter, the EC value may be measured and a confirmation operation such as confirming that the EC value is a predetermined value or less may be performed.

The second is to add calcium as a nutrient solution used for pre-harvest treatment. This is because the biosynthesis of the antioxidant component can be promoted by adding an appropriate amount of calcium.
The third is to irradiate short wavelength visible light. Biosynthesis of antioxidant components can be promoted by irradiating with light of an appropriate wavelength.

By satisfying these three conditions as pre-harvest treatment, vegetables with greatly enhanced various antioxidant components can be obtained.
Several experiments were conducted to demonstrate the effects of the pre-harvest treatment described above. Details of the demonstration experiment will be described below.

<Demonstration experiment 1>
Experiments were conducted to demonstrate the effects of pre-harvest treatment using Komatsuna, Komatsuna Purple, and Chimasanchu.
First, in the growing season, cultivation was carried out under general conditions, and the nutrient solution was switched when the leaves were fully spread. The nutrient solution after switching (nutrient solution for pre-harvest treatment) is calcium sulfate. In addition, the amount of nitrogen in the nutrient solution after switching was 2.0 mg / l. Pre-harvest treatment was performed for 3 days.
For light irradiation, a blue LED was used. The irradiation amount was a photon density of 200 μmol per square meter per second, and a stronger light was irradiated as compared to the growth period.

After cultivating for 3 days using 6 types of nutrient solution, the amount of calcium in the nutrient solution for pre-harvest treatment was changed in the range of 0 mg / l to 140 mg / l, the ORAC value was measured for each.
The ORAC method was used to measure the total amount of all antioxidant components other than carotenoids such as vitamin C, vitamin E, glutathione, cysteine, polyphenol, and sulfur-containing compounds, using the ORAC method.

The results are shown in Table 1.
In any of Komatsuna, Komatsuna purple, and Chimasanchu, the ORAC value greatly depends on the amount of calcium. The ORAC value is greatly improved when the calcium amount is in the range of 50 mg / l to 120 mg / l.

In addition, the same tendency was obtained for the ORAC value with respect to the calcium amount in leaf lettuce, kosletus, chingensai, mustard, etc.
From the above, it has been confirmed that the amount of various antioxidant components contained in vegetables can be improved by setting the amount of calcium in the nutrient solution for pre-harvest treatment within a predetermined range.

<Verification experiment 2>
In the demonstration experiment 1, the dependency of the ORAC value on the calcium amount was examined. In this verification experiment, the calcium amount in the nutrient solution was fixed at 100 mg / l, and the nitrogen amount in the nutrient solution was changed from 0 mg / l to 50 mg. In the range of / l. Using this nutrient solution, the ORAC value was measured for each after 3 days of cultivation. The light irradiation conditions are the same as in the demonstration experiment 1.

The results are shown in Table 2.
In all of Komatsuna, Komatsuna purple, and Chimasanchu, the ORAC values showed better results as the amount of nitrogen was smaller. In particular, when the amount of nitrogen was 2.2 mg or less, the ORAC value was almost saturated and showed a very high value.

In addition, the same tendency was obtained for the ORAC value with respect to the calcium amount in leaf lettuce, kosletus, chingensai, mustard, etc.
From the above, it was confirmed that the amount of various antioxidant components contained in vegetables can be improved by making the amount of nitrogen in the nutrient solution for pre-harvest treatment a trace amount.
Further, from the demonstration experiment 1 and the demonstration experiment 2, in order to greatly improve the ORAC value of vegetables, it is necessary that the amount of nitrogen in the nutrient solution for pre-harvest treatment is very small and the amount of calcium is within a predetermined range. I was able to verify that there was.

<Demonstration experiment 3>
In the demonstration experiment 1 and the demonstration experiment 2, it verified about the nutrient solution component of the pre-harvest process. In this verification experiment, we investigate the effects of light irradiation during pre-harvest processing.
The amount of nitrogen in the nutrient solution for pre-harvest treatment was 2.0 mg / l, and the amount of calcium was 100 mg / l.
As the light irradiation conditions, an LED was used, and a case where only blue light was irradiated and a case where only red light was irradiated were compared. In any case, the irradiation amount was set to a photon density of 200 μmol per square meter per second.
After cultivation for 3 days under the above conditions, the ORAC value was measured for each.

The results are shown in Table 3.
In any vegetable, a high ORAC value was obtained when only blue light was irradiated.
From the above, it was found that in the nutrient solution for pre-harvest treatment, blue light is more effective in improving the amount of various antioxidant components contained in vegetables than red light.
It has been confirmed by another experiment that the content of ascorbic acid hardly depends on the illuminance of red light and depends only on the illuminance of blue light.
As described above, from the viewpoint of improving the ORAC value, it is desirable to use only visible light having a wavelength of 490 nm or less as a light source used for pre-harvest processing. This is because the energy efficiency of irradiation light can be increased and the cost can be reduced. However, the light such as red may be irradiated together. This is because red light or the like promotes nitrogen assimilation and may be effective from the viewpoint of reducing nitrate nitrogen.

<Demonstration experiment 4>
In demonstration experiment 3, it was confirmed that a high ORAC value was obtained with blue light. In this verification experiment, the wavelength region of the irradiation light in which a high ORAC value was obtained was examined.
Irradiation light with which a high ORAC value can be obtained is not only blue light, but also violet light has the same effect. On the other hand, when the wavelength of the irradiation light exceeds 480 nm, the effect is reduced, and when the wavelength is 500 nm or more, the ORAC value is hardly improved.
Therefore, the irradiation light with which a high ORAC value is obtained is visible light of 490 nm or less, and particularly visible light of 480 nm or less was highly effective. The relationship between the ORAC value and the irradiation light wavelength was almost the same for all vegetables.

<Verification Experiment 5>
Next, the relationship between irradiation light intensity and ORAC value was investigated. The results of experiments conducted using vitamin vegetables are described.
The amount of nitrogen in the nutrient solution for pre-harvest treatment was 2.0 mg / l, and the amount of calcium was 100 mg / l.
An LED was used as irradiation light, and only 454 nm blue light was irradiated. The irradiation amount was changed in the range of 100 to 400 micromol per square meter per second, and irradiation was performed for 12 hours a day.
After cultivation for 4 days under the above conditions, ORAC values were measured for each. In addition, ascorbic acid content was also measured separately,

The ORAC value increased as the dose per square meter per second increased. However, from 80 to 400 micromol, the relationship between the irradiation dose and the ORAC value was almost proportional. However, at 70 micromol or less, the ORAC value fluctuated greatly below this proportional relationship.
The relationship between the irradiation amount and the ascorbic acid amount was also the same.

Therefore, in consideration of the energy efficiency of the irradiation light, the irradiation amount is desirably 80 micromol or more per square meter per second.
This tendency was the same even when 380 nm violet light was used. Furthermore, this tendency was almost independent of the type of vegetable.

  The above result is a result of a total irradiation time of 48 hours. The longer the irradiation time, the more the ORAC value was improved, and the relationship between the irradiation time and the ORAC value was almost proportional. Therefore, it was found that the ORAC value of vegetables increases as the light is irradiated for a longer time. However, if the pre-harvest treatment period is too long, the shelf life of the harvested vegetables will deteriorate, so the pre-harvest treatment period will be appropriately determined within the range of 1 to 5 days depending on the variety of vegetables. It is desirable.

  In this verification experiment, not only the ORAC value but also the content of ascorbic acid was measured separately. Even in the light intensity of the chair, the contribution of the ascorbic acid to the ORAC value estimated from the amount of ascorbic acid is 1/10 or less of the total amount of ORAC values. Therefore, it was also verified that vegetables with enhanced various antioxidant components other than ascorbic acid were obtained.

<Discussion>
From the demonstration experiments 1 to 5 described above, it was confirmed that the antioxidant components contained in the vegetables can be greatly improved by cultivating the vegetables under special environmental conditions before harvesting. The special environmental conditions are the following three conditions.
(Condition 1)
Minimize the amount of nitrogen contained in the nutrient solution. Desirably, it is 2.2 mg / l or less.

(Condition 2)
Include calcium in the nutrient solution. Desirably, calcium is contained in the range of 50 mg / l or more and 120 mg / l or less.

(Condition 3)
Irradiate visible light having a wavelength of 490 nm or less. In particular, visible light of 480 nm or less is desirable. The irradiation dose is desirably 80 micromol or more per square meter per second.

  It is unclear what mechanism each of the above three conditions contributes to the production of antioxidant substances. However, as inferred from the remarkable improvement of the ORAC value, it is considered that each of them does not act independently but acts with some kind of mutually related effect or synergistic effect.

1A and 1B are diagrams for explaining the effects of the present invention. FIG. 1A is a metabolic image when a large amount of nitrogen is present, and FIG. 1B is a metabolic image when there is almost no nitrogen.
As shown in FIG. 1 (a), carbon obtained by photosynthesis in a plant is synthesized into an amino acid using nitrogen absorbed from the root, so that the plant grows. On the other hand, as shown in FIG. 1 (b), when nitrogen is deficient, the flow of carbon metabolism fixed by photosynthesis is dominated by the flow of antioxidant components to biosynthesis. Thus, the flow of metabolism can be controlled by controlling the amount of nitrogen contained in the nutrient solution.

However, simply controlling metabolic flow does not mean that large amounts of antioxidants are biosynthesized. Antioxidant biosynthesis is significantly more efficient when “induction into the biosynthetic system” and “control of metabolic flow” are combined, producing large amounts of antioxidants.
For example, in plant cells, calcium is localized in organelles such as chloroplasts, mitochondria, and endoplasmic reticulum. It is known that when some stimulus is given, calcium is released into the cytoplasm, and a specific enzyme reaction is controlled by the released calcium. That is, calcium is known to have a role of acting on a signal transduction system.

  In the biosynthetic system of antioxidant substances, calcium is thought to contribute to the induction of the biosynthetic system by acting on a signal transduction system involved in some biosynthetic pathway. This is one hypothesis, but I think that it is a powerful hypothesis that can explain that a large amount of antioxidants are produced by giving calcium.

It is considered that the same effect can be obtained with light irradiation. For example, there may be a “blue signal transmission system” that does not go through a photosynthesis electron transmission system.
What is estimated from the relationship between the ORAC value and the wavelength property of the irradiated light is that Cryptochrome, a photoreceptor having an absorption region in the same wavelength range, is involved in this signal transmission system. . Cryptochrome is a protein that has not only plants but also algae, and is a protein that plants and algae had from the early stages of evolution. In the verification experiment shown above, the wavelength and irradiation dose dependency of the ORAC value was the same for all vegetables. This is considered to be due to the nature of cryptochrome common to all plants. .
It is known that active oxygen is involved in cryptochrome signal transduction. Therefore, it can be inferred that irradiation with visible light of 490 nm or less is due to induction or activation of biosynthetic pathways of various antioxidant components due to oxidative stress.

That is, in the present invention, the factors that resulted in vegetables with significantly improved various antioxidants were:

1) By using a nutrient solution that contains almost no nitrogen, there is a deficiency of nitrogen in the plant, and the flow of metabolism changes from the flow of amino acid synthesis to the flow of biosynthesis of antioxidants. Light with a wavelength of 490 nm or less is involved in several signal transduction systems, causing changes in plants such as creating conditions where antioxidants are required

This is thought to be because the biosynthesis of antioxidant substances is dramatically accelerated by the simultaneous occurrence of two different changes in the plant body. That is, it is considered that various antioxidant substances are synthesized in large quantities when the plant is in a situation where it needs an antioxidant substance and a metabolic pathway capable of biosynthesizing the antioxidant substance is secured.

  In addition, it is thought that calcium addition to nutrient solution and light irradiation with a wavelength of 490 nm or less are involved in the signal transduction system, and even if only one of them is used, contribution to “induction to biosynthetic system” is recognized. . However, if both are implemented simultaneously, the contribution will increase dramatically.

<Summary of the present invention>
The method for producing vegetables by hydroponics according to the present invention enables the production of vegetables with significantly enhanced various antioxidant components, contributes to the health promotion of those who eat it, aging, cancer, heart disease, It can be expected to improve the preventive effect against many diseases such as stroke and diabetes. It also has the effect of reducing the nitrate nitrogen content.

  There are several reports on pre-harvest treatment in hydroponics, but it is mainly aimed at reducing nitrate nitrogen content and improving the taste associated therewith. Although there are reports on the improvement of ascorbic acid and the like, there is no report on the remarkable improvement of the ORAC value.

  This is thought to be due to the fact that the mechanism of the biosynthetic system of antioxidant substances has not been fully elucidated. In the present invention, as a result of examining various nutrient solutions and light irradiation conditions based on the assumptions shown in the discussion, the pre-harvest treatment is performed using a nutrient solution containing almost no nitrogen and a predetermined amount of calcium. It proved that vegetables with various antioxidant components remarkably enhanced can be cultivated. Moreover, the role of visible light having a wavelength of 490 nm or less was also verified, and it was confirmed that there was a great contribution to the biosynthesis of antioxidant components.

Claims (7)

In a certain period before harvest,
By using a nutrient solution that does not substantially contain nitrogen, a metabolic pathway mainly consisting of biosynthesis of antioxidant components is secured,
A method for producing vegetables with enhanced various antioxidant components by hydroponics, characterized by promoting induction of antioxidant components by adjusting light irradiation conditions and / or nutrient solution conditions. Using nutrient solution that does not contain nitrogen and contains calcium,
By irradiating light including visible light having a wavelength of 490 nm or less,
A method for producing vegetables with enhanced various antioxidant components by hydroponics, characterized by cultivating vegetables for a certain period before harvesting. The intensity of light including visible light having a wavelength of 490 nm or less is 80 micromol or more per square meter. Production of vegetables with enhanced various antioxidant components by hydroponics according to claim 2. Method. The said nitrogen content is 2.2 mg or less per 1 L of said nutrient solution, The production method which strengthened the various antioxidant components by the hydroponic cultivation of Claim 2 or 3 characterized by the above-mentioned. Content of calcium is 50 mg or more and 120 mg or less per 1 L of said nutrient solution. The production method of the vegetable which reinforced various antioxidant components by the hydroponic cultivation in any one of Claim 2 to 4 characterized by the above-mentioned. The method for producing vegetables with enhanced various antioxidant components by hydroponics according to any one of claims 1 to 5, wherein the predetermined period is 1 to 5 days. A method for producing vegetables with enhanced various antioxidant components by hydroponics according to any one of claims 1 to 6, wherein a trace amount of mineral is added to the nutrient solution.