KR20110137387A - Method for increasing useful component content of plant body in hydroponic culture - Google Patents

Abstract

 A method for producing a hydroponic cultivated vegetable having a high content of nutrients such as ascorbic acid, polyphenols, sugars and other useful ingredients such as a food ingredient without the need for additional equipment including a special light source such as an ultraviolet lamp is disclosed. The method is a method of producing a vegetable by hydroponic cultivation, and is characterized by culturing in a state in which at least a part of the root is exposed to air over a predetermined period prior to harvesting the vegetable.

Description

Method of improving useful ingredient content of plant in hydroponic cultivation {METHOD FOR INCREASING USEFUL COMPONENT CONTENT OF PLANT BODY IN HYDROPONIC CULTURE}

The present invention relates to a method for producing vegetables by hydroponic cultivation, and more particularly, to produce vegetables by hydroponic cultivation in which the contents of useful components such as antioxidant components, nutrient components, and flavoring components are increased, and nitrogen nitrogen nitrate content is reduced. It is about a method.

Hydroponic cultivation, which is a method of cultivating plants using nutrient solution containing minerals and other ions without using soil, does not require farmland, and if it is equipped, it is nourished under appropriate conditions regardless of location or natural environment. It has the advantage that it is possible to cultivate the plant under full control of the growth conditions such as light, water, temperature, etc., and it can also speed up the growth of the plant, increase the harvesting efficiency, and adjust the timing of harvesting. Since it is easy, it is widely used for production of agricultural products, such as a vegetable.

However, while vegetables obtained by hydroponic cultivation are fast growing, there is a problem that the content of antioxidants such as ascorbic acid (vitamin C) and various nutrient components tends to be low. In addition, ascorbic acid is known to increase the body's demand when stress is applied, such as influenza or other infectious diseases, etc. In humans, it is preferred to have a high content of vitamin C in vegetables with a health-oriented height. Tend to be.

In addition to the above, vegetables usually contain nitrogenous nitrate, but if it is contained in large amounts, it can lead to the production of carcinogens in addition to causing bitter taste, so that the production of vegetables with reduced content This is preferred.

Conventionally, in hydroponic cultivation, the examination for increasing content of the nutritional component containing antioxidant components, such as an ascorbic acid of a vegetable, is performed. For example, Japanese Unexamined Patent Publication No. 2004-305040 and Japanese Unexamined Patent Publication No. 2008-86272 (Patent Documents 1 and 2, respectively) are located in the vicinity of 315 nm in order to increase the content of functional components such as vitamin C and tocopherol. It is disclosed to irradiate artificial ultraviolet rays having a peak. However, such a method has a disadvantage in that, in addition to the ordinary lighting, an additional facility including a specific ultraviolet lamp is required, the cost is increased, additional energy costs are required, and the control and maintenance of the optimum amount of light are complicated. have.

Japanese Unexamined Patent Publication No. 2004-305040 Japanese Unexamined Patent Publication No. 2008-86272

Under the above background, the present invention eliminates the need for additional equipment including a special light source such as an ultraviolet lamp, and does not incur additional energy costs, and increases the content of useful components such as ascorbic acid, polyphenols, sugars, and the like. An object of the present invention is to provide a method for producing hydroponic vegetables with reduced content.

As a result of the examination for the above purpose, the present inventors, in the final stage of hydroponic cultivation of vegetables, ascorbic acid, polyphenol, sugar by exposing some of the roots immersed in the nutrient solution to the air over a certain period before harvesting Contents of useful components, such as nutrient components (ascorbic acid and polyphenol are also antioxidant components), and a flavoring component, etc., become high, On the other hand, it discovers that nitrogen-nitrate content decreases, and further studies are repeated and this invention is carried out. Completed. That is, this invention provides the following.

1. A method of producing a vegetable by hydroponic cultivation, wherein the production method is characterized by cultivating at least a part of the roots exposed to air over a predetermined period prior to harvesting the vegetable.

2. The said 1 production method whose predetermined period is a period of 2 to 12 days.

3. The at least part of the root exposed to air extends at least 1 cm from the root of the root or at least 3% of the total length from the root of the root, and at least 3 of the total length of the root from the root's tip. The said 1 or 2 production method which does not reach to the part to less than%.

According to the present invention, there is no need for additional equipment including an ultraviolet lamp or the like, and the content of useful components such as ascorbic acid, polyphenols, sugars and other constituents, such as sugar, is increased in an inexpensive manner. Hydroponic vegetables with reduced content can be produced.

BRIEF DESCRIPTION OF THE DRAWINGS It is a graph which shows the ascorbic acid content of each plant of the control group and the root zone partial exposure group in Example 1. FIG.
FIG. 2 is a graph showing the sugar (Brix) of lettuce in the control group and the root zone partial exposure group in Example 1. FIG.
3 is a graph showing the nitrogen-nitrate content of lettuce in the control group and the root zone partial exposure group in Example 1. FIG.
It is a graph which shows the relationship between the exposure length of root zone partial exposure and the increase rate of ascorbic acid content in Example 2. FIG.
FIG. 5 is a graph showing the relationship between the number of root zone exposure days and the increase rate of ascorbic acid content in Example 3. FIG.
It is a graph which shows the polyphenol content of the lettuce of a control group and a root zone partial exposure group in Example 4. FIG.
FIG. 7 is a graph showing the relationship between the root zone partial exposure treatment days and the increase / decrease rate of fresh weight of lettuce in Example 5. FIG.
FIG. 8 is a graph showing the relationship between the root zone partial exposure treatment days and the increase / decrease rate of the water content of lettuce in Example 5. FIG.

In this specification, a "hydroponic cultivation vegetable" means the vegetable obtained by growing by hydroponic cultivation.

In the present invention, in order to expose at least a portion of the roots to the air (root exposure part), for example, a container supporting the plant on the nutrient solution surface is lifted from the nutrient solution surface, or the nutrient solution surface is kept in a lowered state. Thereby, it is convenient to expose the root portion of the root to the air, and specific means therefor are not limited.

In the root zone partial exposure treatment, the length (exposure length) of the portion exposed to the air in the root is preferably 1 cm or more or about 3% or more of the entire length of the root, more preferably 2 cm or more, or At least about 6%, more preferably at least 4 cm, or at least about 13% of the total length of the root. However, it is necessary that at least a part of the root (preferably the tip) is immersed in the nutrient solution, and in the case of the tip, a portion corresponding to about 3% of the entire length of the root may be immersed in the nutrient solution.

Since the effect of the root zone partial exposure treatment is too long (the effect is considered to be because the plant is adapted to the cultivation environment in the root zone partial exposure state), in order to obtain the effect, the number of days of the root zone partial exposure treatment is 2 to 12 days. It is preferable to set it as 4 to 10 days, and it is still more preferable to set it as about 7 days.

Since cultivation by partial exposure to the root zone increases the content of useful components such as ascorbic acid, polyphenols, sugars, and other constituents such as sugar, it is regarded as a fundamental defense response of plants to the air exposure stress of the roots. The method is widely applicable to vegetables in general.

In the present specification, "vegetables" includes "leaf vegetables" and "root vegetables" and "fruits". Here, the term "leaf vegetable" refers to a vegetable for which the leaf portion is edible. For example, lettuce, watercolor, spinach, garland chrysanthemum, litter, bok choy, cabbage, cabbage, perilla, mustard, herbs (rocket, basil, etc.) Although these etc. are mentioned, It is not limited to these. In addition, "root vegetables" refers to vegetables that eat parts of the ground when grown in soil, such as roots and underground diameters.For example, radishes, carrots, turnips, burdock, potatoes, sweet potatoes, taro, lotus root, etc. Although these are mentioned, It is not limited to these. In addition, "fruit vegetable" means the vegetable which makes fruit and a seed edible, and can mention strawberries, a tomato, a cucumber, an eggplant, etc., It is not limited to these.

In addition, in the present invention, the nutrition in hydroponic cultivation, the cultivation conditions such as time / memory of light and dark in one day, the temperature, and the number of days of growth until the root zone partial exposure treatment may be appropriate. What is necessary is just to select suitably well-known various conditions and growth days suitably, and to employ | adopt.

Example

Hereinafter, the present invention will be described in more detail with reference to typical examples, but the present invention is not intended to be limited by the description of these examples.

[Example 1] Root-sphere partial exposure experiment in hydroponic cultivation of lettuce, watercolor, spinach, garland chrysanthemum and litter

Hydroponic cultivation of lettuce, watercolor, spinach, garland chrysanthemum, and litter was carried out. Cultivation conditions were made into the cycle of white 14 hours / dark 10 hours under white fluorescent lamp, and the aqueous solution of the fertilizer (Otsuka House Fertilizer SA prescription) was used as a nutrient solution. The ingredient composition of this nutrient solution is shown in Table 1 below.

The seeds of the plants were sown in a urethane medium, irradiated 6 times / day at an irradiation intensity of 5,000 to 5,500 Lux, at room temperature 18 to 20 ° C, and with a nutrient solution concentration EC (electric conductivity) = 1.0 mS / cm, and grown for 5 days, followed by fresh water By hydroponic cultivation, the panel is fixed in a state where the roots are completely immersed in nutrient solution, and the cultivation intensity is 13,000 to 18,000 Lux, room temperature 20 ° C, nutrient solution concentration EC = 1.8 mS / cm, and it is cultivated for 13 to 26 days depending on plants. did. For each plant, the cultivation days from the sowing to the day before the start of treatment are shown in Table 2 below.

As mentioned above, the various seedling plants were divided into two groups, and the cultivation of one group (control group) was continued for one week under the same conditions as before. For plants of the other group (root zone exposure group), the water level of the nutrient solution was lowered to form a 4 cm gap between the cultivation panel and the nutrient solution surface, and the part extending over the length of 4 cm from the root of the plant roots was the gap. It was made into the state exposed to air, and cultivation was continued over 1 week in that state (root-right partial exposure process). Subsequently, harvesting was carried out to measure sugar content as an index of ascorbic acid content and a flavoring component as an index of nutritional component (and antioxidant component) in the plant, and nitrogen-nitrate content as measured by the following method, respectively. The values were compared with those in plants which did not undergo exposure treatment.

<Measurement of Ascorbic Acid Content>

Method: After crushing a sample using a mixer while adding and diluting a certain amount of 5% metaphosphoric acid to a plant, the crushed liquid was centrifuged at 12,000 rpm for 1 minute. Ascorbic acid concentration was measured with the reflection type photometer RQ flex (made by Fujiwara Corporation) using the supernatant liquid, and it calculated as ascorbic acid content per 100 g of plants.

Results: The results are shown in FIG. As can be seen from the figure, the plant provided for the root zone partial exposure treatment compared with the control group, the ascorbic acid content of 132%, watercolor 123%, spinach 163%, garland chrysanthemum 148%, litchi 144% in lettuce It turned out that all were markedly increased. This shows that it is possible to increase the ascorbic acid content by this invention in various vegetables.

<Measurement of Sugar (Brix (%))>

Method: 100 ml of water was added to a plant and crushed by a mixer, and the crushed liquid was centrifuged at 12,000 rpm for 1 minute. The sugar content of the supernatant was measured using a pocket sugar meter (PAL-1; manufactured by Atago), and based on the value, the sugar content (Brix (%)) was calculated as the weight percentage of the sugar contained in the live plants.

Results: The results are shown in FIG. As can be seen from the figure, when the root portion partial exposure treatment was performed on the lettuce, the sugar content increased to 118% compared to the control group. This indicates that, according to the present invention, the content of the vegetable flavor component can also increase.

<Measurement of nitrogen nitrate content>

Method: For the nitrogen content of nitrogen nitrate, the supernatant prepared in the above `` Measurement of Ascorbic Acid Content '' was diluted with a certain amount of water, and then, as in the case of ascorbic acid, a reflective photometer RQ flex (manufactured by Fujiwara Corporation) was added. It measured using.

Results: The results are shown in FIG. As can be seen from the drawing, the root zone partial exposure treatment reduced the nitrogenous nitrate content to about 90% compared to the control group. This result shows that the nitrogen-nitrate content of vegetables can be reduced by this invention.

EXAMPLE 2 Examination of the relationship between the exposure length and the content of the useful component in the root wound partial exposure treatment

The root length exposed to the air by forming ten groups having 0.5, 1, 2, 4, 5, 10, 15, 20, 25, or 30 cm in the gap between the panel and the nutrient solution in the root zone exposure treatment ( Lettuce was grown and harvested by the method similar to Example 1 except having made exposure length) into any of these lengths. In addition, the root length at the start of the root zone partial exposure treatment was 30.9 cm on average, and in the group of 30 cm exposure length, the tip of the root was only slightly submerged in the nutrient solution. Ascorbic acid content was measured about the harvested lettuce by the method similar to Example 1.

The results are shown in FIG. As can be seen from the figure, the ascorbic acid content was increased to 105% of the control by exposing 1 cm (3.2% of the root) of the roots, although no change was seen with the control at the exposure length of 0.5 cm. However, it increased further as the exposure length was extended, and increased to 125% or more at an exposure length of 4 cm or more. Even when the 30 cm exposure length (97% of the whole root) was exposed, the ascorbic acid content was increased to 130% of the control group. This result exposes the root of the plant to the air, preferably at least 1 cm, more preferably at least 2 cm, even more preferably at least 4 cm from the base, provided that the entire length of the root is at the tip side of the root. Cultivated for a period of about one week immediately before harvest, with at least 3% of its length submerged in the nutrient solution (ie, with the root zone partial exposure less than 3% of the total length of the root from the tip of the root). It has shown that it is effective for increasing content of useful components, such as nutritional components, such as ascorbic acid, sugar, and a taste component, in a plant.

[Example 3] Examination of the relationship between the number of treatment days and useful component content in root wound partial exposure treatment

In order to examine the relationship between the root zone partial exposure treatment days and the useful component content of the plant, the lettuce was seeded in the same manner as in Example 1, and then the exposure length was 4 cm, 0, 3, 7, 9, 12 or The root zone partial exposure treatment was performed over 14 days, the plants were harvested, and the ascorbic acid content was measured.

The results are shown in FIG. In the rhizosphere partial exposure group, ascorbic acid increased to 111% compared to the control group after 3 days of rhizosphere partial exposure treatment, and further increased up to 7 days of treatment. However, after that, the increase rate with respect to the control group decreased, and the result of the treatment for 12 days became equivalent to the treatment for 3 days, and for the treatment for 14 days, it became equivalent to the control and returned to the state before the increase of ascorbic acid. This is thought to be due to the plant's compliance with the growing environment in the root zone partial exposure. The results indicate that the number of days of the root zone partial exposure treatment is preferably 2 to 12 days, more preferably about 4 to 10 days, and even more preferably about 7 days.

[Example 4] Examination of the influence of the root zone partial exposure treatment on the polyphenol content

In order to examine the influence on the polyphenol content of the plant by the root zone partial exposure treatment, the lettuce was grown in the same manner as in Example 1, and then the water level of the nutrient solution was lowered to reduce the 4 cm between the cultivation panel and the nutrient solution surface. A gap was formed, and the part over the length of 4 cm of the root part of the plant root was made to be exposed to air in the gap, and cultivation was continued for one week in that state (root zone partial exposure treatment). Next, it harvested and measured the polyphenol content in a plant by the following method.

<Measurement of Polyphenol Content>

10 ml of 80% ethanol was added to 1 g of the sample obtained by freezing and crushing the plant in liquid nitrogen, and the supernatant obtained by centrifuging for 5 minutes at 3000 rpm for 2 hours in a cool and dark place was used as the polyphenol extract.

The polyphenol content of the extract was measured by the Pauline-Ciocalto method. That is, 1 ml of a phenol reagent (manufactured by MP Biochemical Co., Ltd.) diluted in 1/2 was added to 1 ml of the extract, mixed, and 1 ml of a 10% aqueous sodium carbonate solution was added and stirred, and the mixture was stopped at room temperature for 60 minutes. Then, the absorbance of absorbance 700nm was measured with the spectrophotometer (UV-160; Shimadzu Corporation). Quercetin was used as a reference sample, and the polyphenol content in the sample was calculated as quercetin equivalent (mg quercetin / fresh weight).

The results are shown in FIG. As shown in the figure, the content of polyphenol increased to 151% of the control group in the lettuce treated with the root zone exposure treatment. This indicates that the polyphenol content is also improved by the root zone exposure treatment.

[Example 5] Examination of the influence of root exposure exposure treatment on the water content of plants

In the same manner as in the above experiment, the root portion partial exposure treatment was performed on the lettuce for 3 to 14 days with a space between the cultivation panel and the nutrient solution surface of 4 cm. After the treatment, dry weight and fresh weight were measured to calculate moisture content.

The results are shown in FIGS. 7 and 8. As shown in FIG. 7, there was almost no negative effect on growth by the root zone partial exposure treatment for 3 to 10 days. In 14 days of treatment, however, a decrease in yield of about 10% was observed. On the other hand, as shown in FIG. 8, the moisture content hardly changed during the treatment period, and it was found that there was no influence on the quality such as texture.

In addition, from this result, it is thought that the increase of the content of the nutritional component and the antioxidant component in the series of examples is not an increase in concentration, but an increase in absolute amount. In addition, by exposing a part of the roots to the air as described above for 2 to 12 days, it was evident that there was no adverse effect on the quality of crops (growth) and texture. Industrial availability

The present invention eliminates the need for additional equipment such as ultraviolet lamps and the like, and makes it possible to produce hydroponic cultivated vegetables having a high content of useful ingredients such as ascorbic acid, polyphenols, sugars, etc. in a cost-free manner. It is useful for producing these rich and tasty vegetables at low cost.

Claims (3)

A method of producing a vegetable by hydroponic cultivation, wherein the method is characterized by cultivating at least a part of the roots exposed to air over a predetermined period prior to harvesting the vegetable. The method of claim 1,
The production method whose predetermined period is a period of 2-12 days. The method according to claim 1 or 2,
The at least a portion of the root exposed to air extends over 1 cm from the root of the root or over 3% of the total length from the root of the root, and extends from the tip of the root to less than 3% of the root of the root. Production method that is not.

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