CN111031787B - Method for increasing ascorbic acid content of leaf vegetables - Google Patents

Abstract

A method for increasing ascorbic acid content of leaf vegetables comprises supplying nutrient solution containing mannose to cultivate leaf vegetables. Preferably, the leaf vegetables are harvested by supplying a nutrient solution containing the mannose. More preferably, the nutrient solution is supplied after the formation of lateral roots of the leaf vegetables or after the m-th day after the sowing of the leaf vegetables (m is 5 or more).

Description

A method for increasing the ascorbic acid content of leafy vegetables

technical field

The present invention relates to a plant cultivation method, and particularly relates to a plant cultivation method for increasing the content of vitamin C (or, also referred to as ascorbic acid) in a plant.

Background technique

In recent years, from the viewpoint of health needs and the like, research to increase the content of nutrients such as vitamins in vegetables and fruits has been actively conducted.

Many vegetables and fruits contain vitamin C. In recent years, simple and rapid equipment analysis methods for vitamin C have been developed. In addition, quality breeding is performed for the purpose of increasing the vitamin C content in vegetables and fruits.

Patent Document 1 discloses a method for increasing the vitamin C content of a harvest by inoculating fruit and vegetable seedlings with cucumber mosaic virus and performing cultivation management.

The method of Patent Document 1 is a cultivation method that requires an attenuated cucumber mosaic virus that has little viral side effect and has no influence on cultivation, and requires specialized knowledge. Therefore, the method of Patent Document 1 is not a cultivation method that a general agricultural worker can easily perform.

Patent Document 2 describes that the content of vitamin C, tocopherol, and polyphenols in vegetables such as kombucha is increased by irradiating ultraviolet rays using a health lamp for health wires.

In Patent Document 3, it is described that the content of ascorbic acid and polyphenol in the onion is increased by irradiating UV-B ultraviolet rays.

Patent Document 4 describes that for vegetables grown in hydroponics under artificial lighting, the nutrient solution is replaced with water before harvesting, and the time of day is set to 17 hours or more to carry out water for one day or more. Cultivation, thereby increasing the content of vegetable sugar, whole sugar, ascorbic acid, anthocyanins, polyphenols, chlorophyll, and/or glucosinolates.

Patent Documents 2 to 4 have the following problems.

1) Equipment costs for adjusting the ultraviolet rays and adjusting the time of day are spent.

2) The work of controlling artificial light and the like is complicated.

3) Although laboratory-scale cultivation is possible, cultivation on a commercial scale is difficult.

Patent Document 1: Japanese Patent Application Laid-Open No. 7-250567

Patent Document 2: Japanese Patent Laid-Open No. 2004-305040

Patent Document 3: Japanese Patent Laid-Open No. 2008-086272

Patent Document 4: International Publication No. 2010-140632

SUMMARY OF THE INVENTION

An object of the present invention is to provide a plant cultivation method capable of increasing the content of vitamin C in cultivated leafy vegetables without inoculating a virus and adjusting the ultraviolet rays.

The inventors of the present application found that the above-mentioned problems can be solved by supplying a nutrient solution containing mannose to cultivate leafy vegetables, leading to the completion of the present invention.

That is, the plant cultivation method of the present invention is a method for cultivating leafy vegetables by supplying a nutrient solution, wherein the nutrient solution contains mannose.

In one aspect of the present invention, the leafy vegetables cultivated by supplying the nutrient solution containing the mannose are harvested.

In one aspect of the present invention, the nutrient solution containing the mannose, wherein m is 5 or more, is supplied after the lateral roots of the leafy vegetables are formed or after the m-th day after sowing the leafy vegetables.

In one aspect of the present invention, a nutrient solution to which at least 0.15 mM or more of mannose has been added is supplied as the nutrient solution after the m-th day after sowing and until the harvest day or until n days before the harvest day, Among them, m is 10 or more, and n is 1 or more.

In one embodiment of the present invention, the nutrient solution further contains nitrate nitrogen, phosphoric acid and potassium.

In one aspect of the present invention, leafy vegetables are cultivated by supplying the nutrient solution to the upper surface side of the bottom surface of the cultivation bed using a cultivation bed having a slope.

In one aspect of the present invention, the cultivation bed has a moisture space.

In one aspect of the present invention, a planting plate is arranged on a sloped cultivation bed, the planting plate is provided with a plurality of planting holes, the seedling root mass is placed on the cultivation bed through the planting holes, and the cultivation is directed toward the cultivation bed. The above-mentioned nutrient solution is supplied to the upper surface side of the bottom surface of the bed, and the film hydroponics type hydroponics of leafy vegetables is cultivated.

In one aspect of the present invention, a plurality of ridges extending along the slope direction are provided on the upper surface of the cultivation bed, the ridges are located below the planting holes, and the ridges are concave strips between each other , the seedling root mass is placed on the convex strip, and the nutrient solution is made to flow in the concave strip.

In one form of this invention, a hydrophilic sheet is arrange|positioned on the upper surface side of the bottom surface of the said cultivation bed.

In one embodiment of the present invention, the leafy vegetables are Sapinaceae, Cruciferae, Amaryllidaceae, Umbelliferae, Lamiaceae, Amaranthaceae, Compositae or Chenopodiaceae.

The nutrient regulator of leafy vegetables of this invention is a nutrient regulator used for the nutrient solution cultivation of leafy vegetables, and it is characterized by containing mannose.

According to the present invention, the vitamin C content in the cultivated leafy vegetables can be increased by supplying the nutrient solution containing mannose to the leafy vegetables.

Description of drawings

Fig. 1 is a perspective view of a cultivation bed.

FIG. 2 is a cross-sectional view of a convex portion of FIG. 1 .

3 is a cross-sectional view of a cultivation bed in plant cultivation.

FIG. 4 is a plan view illustrating a cultivation facility.

Detailed ways

Hereinafter, the present invention will be described in more detail, but the present invention is not limited to the following embodiments as long as the effects of the present invention are exhibited.

The leafy vegetables cultivated by the method of the present invention are preferably of the family Sapinaceae, Cruciferae, Amaryllidaceae, Umbelliferae, Lamiaceae, Amaranthaceae, Compositae or Chenopodiaceae, and are especially suitable for spinach.

In the plant cultivation method of the present invention, leafy vegetables are cultivated using a nutrient solution. In the present invention, a nutrient solution containing mannose is supplied to leafy vegetables.

In addition, the nutrient regulator for leafy vegetables of the present invention is a nutrient regulator for use in the nutrient solution cultivation of leafy vegetables, contains mannose, and is used as the mannose-containing nutrient solution used in the present invention, or as a nutrient solution for use in the present invention. It is used as an additive for preparing the nutrient solution containing mannose used in the present invention.

Mannose is a type of monosaccharide classified as aldohexose, and there are optically isomeric forms of D body and L body. As a monomer, the D body is contained in a fruit, a peel, or the like. L bodies do not occur naturally. As the mannose of the present invention, either the D-form or the L-form can be used. D-form mannose is preferably used from the viewpoint of easy availability.

Mannose is well known as a sugar involved in the ascorbic acid biosynthesis pathway. L-ascorbic acid is biosynthesized by photosynthetic organisms such as plants and most animals except some organisms such as primates and mice including humans.

Consider the following pathways in the ascorbic acid biosynthesis pathway of photosynthetic organisms.

1) Routes for derivatives of D-mannose and L-galactose converted from D-fructose 6-phosphate as metabolic intermediates

2) The route of converting D-hemi-creatine from UDP-D-hemi-creatine as a metabolic intermediate

3) D-glucuronic acid pathway converted from D-glucose 1-phosphate

The D-mannose·L-galactose pathway is considered to be the main pathway for ascorbic acid biosynthesis in plants.

As a result of research by the present inventors, it was found that among the monosaccharides in the D-mannose/L-galactose pathway, which is the main pathway for ascorbic acid biosynthesis, only mannose has an effect of increasing ascorbic acid.

Mannose is known to have an effect of inhibiting germination of seeds of experimental plants (Arabidopsis thaliana) or germinated vegetables (germination). Therefore, it is thought that it is impossible to harvest a plant without withering by supplying a nutrient solution containing mannose. That is, the use of a nutrient solution containing mannose for the cultivation of vegetables to be eaten by harvested parts with a certain degree of cultivation period, such as leafy vegetables, has not been realized so far. As a result of intensive research, the inventors of the present application have found that, even if a nutrient solution containing mannose is used for the nutrient solution cultivation of leafy vegetables, the plant can be harvested without withering and the ascorbic acid content of the plant can be increased. Increase.

The preparation method of the mannose-containing nutrient solution is not particularly limited. A predetermined amount of mannose may be added to the existing nutrient solution that does not contain mannose during cultivation, or mannose may be added to the liquid fertilizer stock solution in advance, stirred and mixed to prepare a mixed solution, and the mixed solution may be added for cultivation. of existing mannose-free nutrient solutions.

Powdered mannose may be added to a nutrient solution or liquid fertilizer stock solution, or an aqueous mannose solution may be prepared by dissolving mannose in a cultivation nutrient solution or water in advance, and the mannose aqueous solution may be added to the nutrient solution or liquid fertilizer stock solution. The latter addition method is preferable from the viewpoint of making the distribution of mannose in the nutrient solution used for cultivation more uniform.

Therefore, the nutritional regulator for leafy vegetables of the present invention may be obtained by adding mannose to a nutrient solution or a liquid fertilizer stock solution. In addition, as described later, nitrate nitrogen, phosphoric acid, and potassium may be contained.

A commercial item can be used for mannose. For example, "D(+)-mannose" manufactured by Wako Pure Chemical Industries, Ltd., "D-(+)-mannose" manufactured by Nakalac Co., Ltd., "D-(+)-mannose" manufactured by Sigma-Aldrich. -(+)-Mannose" etc.

In one aspect of the present invention, it is preferable to supply the nutrient solution containing mannose to the leafy vegetables during a predetermined period of time during which the leafy vegetables are cultivated. During cultivation of leafy vegetables, as one aspect of the present invention, the timing of supplying the nutrient solution containing mannose, that is, the timing of adding mannose to the nutrient solution, is after the formation of lateral roots of the leafy vegetables or after the sowing of the leafy vegetables After the mth day and until the harvest date or to the period n days before the harvest date. Here, the period at which the lateral roots are formed refers to the period at which the lateral roots can be confirmed by visual observation in 50% or more of the germinated individuals in the cultivated seedlings. Moreover, the preferable value of m is 5 or more, More preferably, it is 10 or more, More preferably, it is 13 or more, Especially preferably, it is 16 or more. The preferable value of n is 1 or more. For example, during the cultivation period after the m-th day after sowing, the nutrient solution may always contain mannose, or the nutrient solution may contain mannose only during the period specified in the above-mentioned cultivation period. Hydroponics of mannose. In addition, a period during which the nutrient solution containing no mannose is supplied may be provided between the periods during which the nutrient solution containing mannose is supplied.

By using the nutrient solution containing mannose as described above, the content of vitamin C in the leafy vegetables thus harvested increases.

In one aspect of the plant cultivation method of the present invention, 0.06 mM or more of mannose, particularly preferably 0.10 mM or more of mannose, and more preferably 0.15 mM or more of mannose are added to the nutrient solution used for cultivation during the above-mentioned predetermined period. of mannose. In addition, in order to increase the vitamin C content in leafy vegetables more efficiently, it is preferable to add 0.18 mM or more of mannose to the nutrient solution used for cultivation during the above-mentioned predetermined period, depending on the type of leafy vegetables, especially Preferably, 0.2 mM or more of mannose is added, and more preferably 0.3 mM or more of mannose is added. By making the addition amount of mannose in the nutrient solution more than the above-mentioned lower limit, the vitamin C content in the cultivated leafy vegetables can be efficiently increased.

The upper limit of the amount of mannose added to the nutrient solution is not particularly limited, but is preferably 5.0 mM or less, more preferably 3.0 mM or less, still more preferably 2.0 mM or less, and particularly preferably 1.0 mM or less. Since the growth of leafy vegetables is healthy by making the addition amount of mannose in the nutrient solution not more than the said upper limit, it is preferable.

In the present invention, the amount of mannose added to the nutrient solution is, for example, the increased amount of mannose concentration in the nutrient solution measured in the nutrient solution tank after adding mannose. Regardless of whether the supply method of the nutrient solution in the cultivation apparatus is a flow type or a nutrient solution circulation type, the above-mentioned suitable addition amount of mannose in the present invention is preferably an increase in the mannose content in the nutrient solution tank measured after the addition. A nutrient solution was prepared by adding mannose so that it might fall within the said range.

The mannose content of the nutrient solution can be measured, for example, by high-speed liquid chromatography.

When adding mannose to the nutrient solution, mannose may be added to the nutrient solution only once, or may be added multiple times at intervals. In the case of adding mannose multiple times, the amount of mannose added at each addition may be the same within the range shown above, or the amount added at the initial addition may be reduced, and the later the cultivation period, the higher the amount of mannose added. Increase the amount of addition. When adding mannose a plurality of times, the interval of addition is preferably 1 day or more and 7 days or less, and particularly preferably in the range of 2 days or more and 5 days or less. In addition, from the viewpoint of continuing the effect of adding mannose to the nutrient solution, the present invention is preferably applied to a cultivation apparatus for circulating the nutrient solution.

In the cultivation period of the present invention, the total amount of mannose added to the nutrient solution, that is, the upper limit of the total amount of mannose added is not particularly limited, but the total amount of mannose added is preferably 15.0 mM or less, It is more preferably 10.0 mM or less, still more preferably 5.0 mM or less, and particularly preferably 3.0 mM or less. By making the upper limit of the total addition amount of mannose in the cultivation period into the above-mentioned range, it is possible to further suppress the occurrence of growth failure of cultivated leafy vegetables, which is preferable.

Since the mannose in the nutrient solution is hardly absorbed by the leafy vegetables, it is considered that when mannose is added to the nutrient solution in a cultivation apparatus for circulating the nutrient solution, most of the added mannose remains in the nutrient solution as it is. in nutrient solution.

The nutrient solution used in the present invention is not particularly limited, but preferably contains at least nitrate nitrogen, phosphoric acid, and potassium. The content of nitrate nitrogen in the nutrient solution is preferably in the range of 8.0 me/L or more and 25.0 me/L or less, and more preferably in the range of 10.0 me/L or more and 20.0 me/L or less. The content of phosphoric acid is preferably in the range of 3.0 me/L or more and 7.0 me/L or less, and more preferably in the range of 4.0 me/L or more and 6.5 me/L or less. In addition, the content of potassium is preferably in the range of 3.0 me/L or more and 14.0 me/L or less, and more preferably in the range of 5.0 me/L or more and 12.0 me/L or less. By making the nitrate nitrogen, phosphoric acid, and potassium contents in the nutrient solution within the above-mentioned ranges, the effect of increasing vitamin C by mannose can be further enhanced.

In the plant cultivation method of this invention, it is preferable to cultivate leafy vegetables using the cultivation apparatus which circulates a nutrient solution and cultivates.

In one form of this invention, a cultivation apparatus is equipped with the cultivation bed which has a slope. The above-mentioned nutrient solution was supplied to the upper surface side of the bottom surface of this cultivation bed, and leafy vegetables were cultivated.

Preferably, a planting plate with a plurality of planting holes is arranged on a sloped cultivation bed, the seedling root mass is placed on the cultivation bed through the planting holes, and the nutrient solution is supplied to the upper surface side of the bottom surface of the cultivation bed to grow leafy vegetables. A space is formed between the planting board and the bottom surface of the cultivation bed, and the space is a moisture space.

That is, in one aspect of the present invention, the cultivation apparatus is preferably a thin-film hydroponic (NFT) hydroponic apparatus. Thereby, the nutrient solution can be circulated at a certain flow rate, the mannose distribution in the nutrient solution becomes uniform, and the mannose can be supplied to the roots of leafy vegetables sufficiently and uniformly.

In one aspect of the present invention, it is more preferable that a plurality of ridges extending in the gradient direction are provided on the upper surface of the cultivation bed, the ridges are located below the planting holes, and the ridges are concave rows between each other. , the above-mentioned seedling root mass is placed on the convex strip, and the above-mentioned nutrient solution is made to flow in the above-mentioned concave strip. More preferably, the cultivation apparatus arranges a hydrophilic sheet on the upper surface side of the bottom surface of the cultivation bed, supplies a nutrient solution to the upper surface side of the bottom surface of the cultivation bed, and cultivates leafy vegetables.

By using such a cultivation apparatus, the nutrient solution can be circulated on the upper surface side of the bottom surface of the cultivation bed at a certain flow rate, the distribution of mannose in the nutrient solution becomes uniform, and the nutrient solution can be supplied to the leafy vegetables sufficiently and uniformly. root. Thereby, the nutrient solution containing mannose can be efficiently supplied to the roots of leafy vegetables.

The said cultivation apparatus may be equipped with the temperature adjustment means and the density|concentration adjustment means of a nutrient solution which hold|maintain the supplied nutrient solution within the predetermined temperature range.

The temperature adjustment unit maintains the temperature of the circulating nutrient solution within a preset range throughout the year. The temperature adjustment unit includes a temperature sensor that detects the temperature in the nutrient solution tank, a heat exchanger that is arranged in the nutrient solution tank and exchanges heat with the nutrient solution, and a heat medium supply line that supplies a heat medium to the heat exchanger (temperature adjustment line), and a control valve etc. which are interposed in the heat medium supply line and control the supply amount of the heat medium supplied to the heat exchanger based on the detection signal from the temperature sensor.

The concentration adjustment unit is composed of a plurality of stock solution tanks for nutrient solutions, a transfer line, a three-way switching valve (on-off valve), and the like. The nutrient solution in each nutrient solution tank is transported to the nutrient solution tank by a pump, the three-way switching valve (on-off valve) is sandwiched in the transfer line, and the concentration adjustment unit can adjust the concentration of the circulating nutrient solution.

Preferably, protruding strips are formed under the planting holes of the planting plate on the upper surface of the planting bed. The width of the ridges is determined by the diameter of the seedling root mass used. If the width of the ridges is narrower than the diameter of the seedling root mass, there is a possibility that the seedling root mass falls off the ridge-shaped convex portion and inclines. The width of the ridges is more preferably larger than the diameter of the seedling root mass to be used, and smaller than the width obtained by adding 4 mm to the diameter of the seedling root mass.

The nutrient solution flowing on the upper surface of the cultivation bed flows in the concave lines between the convex lines of the cultivation bed. The seedling root mass inserted into the planting hole is placed on the upper surface of the ridge. Since the seedling root mass is not washed away by the flow of the nutrient solution, the medium for the seedling root mass is suppressed from collapsing or the medium flowing out.

According to this cultivation bed, it is possible to generate two roots having different forms and functions, namely, a submerged root that grows in water, and a submerged root that is maintained in moisture and has a plurality of root hairs. The roots in the water mainly absorb the fertilizer and water in the nutrient solution, and the roots in the moisture mainly absorb oxygen directly from the moisture.

It is considered that by supplying a nutrient solution containing mannose, the roots in water, that is, the roots in water, receive stress due to mannose while absorbing nutrients. Thereby, compared with the case of normal cultivation (in the case of cultivation in the nutrient solution which does not contain mannose), the root in the moisture, that is, the root in the moisture increases and becomes very active. From this, it is thought that the content of vitamin C in leafy vegetables increases.

According to this cultivation method, a plant can be cultivated not only relying on the dissolved oxygen in the nutrient solution, but also in the cultivation in the high temperature period when the dissolved oxygen is likely to be insufficient, the root of the plant is not deprived of oxygen.

The preferable structure of this cultivation bed is demonstrated with reference to FIGS. 1-3. An example of the cultivation facility provided with the cultivation apparatus which has this cultivation bed is shown in FIG. 4. FIG.

As shown in FIGS. 1 to 3 , a plurality of planting holes 52 are drilled in the planting plate 51 formed of lightweight foamed styrene or the like. As an example, the size of the planting plate 51 is 600 mm in width, 1000 mm in depth, and 35 mm in thickness. The shape of the planting hole 52 may be an inverted conical shape, but preferably a cylindrical shape with the same diameter up and down. The size of the planting hole 52 is larger than the diameter of the seedling root mass 54 used. The interval of the planting holes 52 is determined to be an appropriate interval according to the type of leafy vegetables to be cultivated. For example, in the case of spinach, if the size of the planting plate 51 is as described above, the cylindrical planting holes 52 having a diameter of 27 mm are arranged in a total of 45 rhombic shapes at intervals of 118 mm.

The cultivation bed 53 on which the above-mentioned planting plate 51 is placed on the upper surface is molded from light-weight foamed styrene similarly to the planting plate 51 . In the example shown in the figure, the two planting boards 51 are supported by the stepped parts 59 and 59 formed in the both side edge parts of the cultivation bed 53 and the receiving part 60 formed in the center of the upper surface. As an example of the size of the cultivation bed 53, the width is 1260 mm, the depth is 1000 mm, and the height of the side wall is 100 mm.

A plurality of rows of ridges 56 that are continuous in the longitudinal direction are formed on the bottom surface portion of the cultivation bed 53 that abuts directly below the planting holes 52 of the planting plate 51 . The nutrient solution L flows down in the concave line 55 between the convex lines 56 and 56 . The height of the ridges 56 is determined by the relationship with the liquid depth of the nutrient solution L. As shown in FIG. The width of the ridges 56 is determined by the diameter of the seedling root mass 54 . If the height of the ridges 56 is too low, the possibility of the seedling root mass 54 placed on the ridges 56 being washed away by the nutrient solution L increases, which is not preferable. On the contrary, if the height of the ridges 56 is too high, the seedling roots Since the distance between the lump 54 and the liquid surface of the nutrient solution L becomes too large, the supply of water to the seedling root lump 54 becomes insufficient and the growth is slow, which is not preferable. If the width of the ridges 56 is narrower than the diameter of the seedling root balls 54 , the seedling root balls 54 may fall off from the ridge-shaped ridges 56 and be inclined. Preferably, the height of the ridges 56 is higher than the liquid depth of the nutrient solution L by about 2 to 3 mm. Preferably, the width of the ridges 56 is larger than the diameter of the seedling root mass 54 and smaller than the width obtained by adding 4 mm to the diameter of the seedling root mass 54 . The interval between the protruding strips 56 is equal to the interval between the planting holes 52 .

Preferably, the plurality of cultivation beds 53 are continuously installed in the longitudinal direction, and installed at a slope of about 1/50 to 1/150. In this case, as shown in FIG. 2 , it is preferable to cover the entire upper surface of the cultivation bed 53 provided continuously with a plastic sheet 57 to prevent water leakage at each consecutively provided site, and to lay a cloth, paper, etc. on the plastic sheet 57 . Aqueous sheet 58. The hydrophilic sheet 58 is used to pick up liquid by capillary action. In the present invention, the flow rate of the nutrient solution is preferably 5 to 30 liters per minute, more preferably 10 to 20 liters. In the present invention, the flow velocity of the nutrient solution refers to the flow velocity of the nutrient solution supplied to the cultivation apparatuses such as the cultivation beds installed continuously, and is measured by the discharge line in the piping to the cultivation apparatuses such as the cultivation beds.

As shown in FIG. 3 , the planting plate 51 is covered on the cultivation bed 53 , and the seedling root mass 54 is dropped from the planting hole 52 . The seedling root mass 54 is placed on the ridges 56 of the cultivation bed 53 facing directly below the planting hole 52 . Next, the nutrient solution L is made to flow in the grooved line 55 from the upstream side toward the downstream side of the cultivation bed 53 . When the flow rate of the nutrient solution L is 10 liters/min per cultivation bed, the liquid level in the tank is about 2-3 mm. This is about half the height of the rib 56 . A humid space with a height of about 25 mm is formed between the lower surface of the planting plate 51 and the liquid level of the nutrient solution L in the tank.

In the above description, the cultivation bed 53 is made of foamed synthetic resin such as foamed styrene. However, various plate-shaped or disc-shaped members in which convex lines and concave lines are alternately formed in parallel, such as a corrugated sheet of synthetic resin, may be used. .

As illustrated in FIG. 4 , the cultivation facility to which the cultivation apparatus of the present invention is applied preferably includes a mother tank 86 for storing the diluted nutrient solution, at least one or more sub-tanks 73 for supplying the nutrient solution from the mother tank 86 , And at least one cultivation bed 53 to which the nutrient solution is supplied from the sub-tank 73 is arranged.

Water such as liquid fertilizer stock solution and tap water in the stock solution tank (not shown) is supplied to the mother tank 86 from pipes 84 and 85 with supply control valves 84a and 85a to prepare a nutrient solution of a predetermined concentration. The nutrient solution of predetermined concentration prepared in the mother tank 86 is distributed and supplied to each sub-tank 73 via the pump 87 , the piping 88 , the three-way valve 89 , the flow meter 90 and the spherical cock 91 . The water supply piping 92 is connected to the three-way valve 89 , and the water from the piping 92 can be supplied to the sub-tank 73 by switching the three-way valve 89 . The liquid in each sub-tank 73 is supplied to each cultivation bed 53 via the pump 74 and the piping 75 .

In FIG. 4, the some cultivation bed 53 is arrange|positioned, and leafy vegetables are cultivated. The nutrient solution prepared in the mother tank 86 is supplied to the plurality of cultivation beds 53 through the sub-tank 73 . Thereby, the nutrient solution (diluted nutrient solution) of the uniform concentration prepared in the mother tank 86 can be always supplied to each cultivation bed 53 .

In FIG. 4 , the cultivation bed group 62 is formed by arranging the cultivation bed row 61 in which the plurality of cultivation beds 53 are arranged in one row with a gradient in a plurality of rows (four rows in the figure). One sub-tank 73 is attached to one cultivation bed group 62 .

In the cultivation apparatus of FIG. 4 , mannose is preferably added to the sub-tank 73 .

As shown in FIG. 4 , by providing the sub-tanks 73 for each cultivation bed group 62 , it is possible to manage the cultivated nutrient solution in the sub-tanks 73 in a relatively small amount. It is preferable to discard the nutrient solution used in one cultivation bed group 62 when harvesting is completed, and start subsequent cultivation with a new nutrient solution.

As a result, the vegetables to be cultivated in the next stage can be further cultivated without being affected by exudates (organic acids, etc.) derived from the roots, shedding of epidermal cells of the roots, and the like that flow out into the nutrient solution due to the cultivation in the previous stage. Cultivated stably.

In the conventional method, since the nutrient solution is supplied to each cultivation bed through a common tank for cultivation, the nutrient solution used is replenished with a new nutrient solution each time, and the nutrient solution is reused each time. It accumulates in the epidermal cells of the plant or the root, and with repeated cultivation, a growth retardation called autopoisoning occurs.

In the conventional method, all the nutrient solutions can be replaced, but since the nutrient solution is replaced in all the pots and each cultivation bed at the same time, a large amount of the nutrient solution is discarded at the same time, and all the leafy vegetables cannot be processed in this operation. cultivation. As a result, leafy vegetables such as vegetables cannot be shipped during this period, and there is a problem that regular shipment of vegetables cannot be performed.

In FIG. 4 , the nutrient solution used in one cultivation bed group 62 is returned to the sub-tank 73 for supplying the nutrient solution to each cultivation bed 53 of the cultivation bed group 62 via the piping 76, and the nutrient solution is circulated. In the sub-tank 73, the nutrient solution is increased from the mother tank 86 through the spherical cock 91 or the like, and the nutrient solution in the sub-tank 73 is kept constant.

In FIG. 4 , cleaning (cleaning after harvesting) or the like is performed in other cultivation bed groups 62 while cultivation is continued in some cultivation bed groups 62 , and the steps can be performed for each cultivation bed group 62 .

In addition, even when pathogenic bacteria are generated in one cultivation bed group 62, infection of other cultivation bed groups 62 by pathogenic bacteria can be suppressed. That is, since the nutrient solution is not returned to the mother tank 86, the contamination remains only in the closed circuit (cultivation bed group 62) in which the nutrient solution is circulated.

Water can be introduced into each sub-tank 73 via the water supply piping 92 and the three-way valve 89 . In the late stage of cultivation of leafy vegetables cultivated in each cultivation bed group 62 , the fertilizer concentration of the nutrient solution circulating in the sub-tank 73 and the cultivation bed 53 can be reduced by switching from the supply of the nutrient solution to the supply of water. As a result, the amount of nitric acid in the plant can be gradually decreased in the later stage of cultivation, and leafy vegetables can be harvested in a state in which the amount of nitric acid is decreased.

Once the nitric acid in the plant is obtained by the human body, it combines with nitrogen in the amide state to form nitroaniline. By reducing the fertilizer concentration of the nutrient solution in the later stage of cultivation, the concentration of nitric acid in the plant can be reduced. In addition, nitrogen, phosphoric acid, and potassium in the nutrient solution to be used are at low concentrations in the late stage of cultivation, so that even in the process of discarding the nutrient solution after harvesting, the load on the environment can be greatly reduced.

Example

[Basic conditions]

As a basic condition, the cultivation bed shown in FIGS. 1 to 3 with a slope of 1/100 has a planting plate with 270 planting holes drilled therethrough, and a hydrophilic sheet is placed on the upper surface side of the bottom surface of the cultivation bed, The nutrient solution was supplied to the bottom surface of the cultivation bed at a flow rate of 20 liters per minute (nutrient solution concentration: EC3.0 dS/m, nutrient solution temperature: 20°C, nitrate nitrogen; 14me/L, phosphoric acid: 4me/L, potassium : 10me/L) circulating thin-film hydroponic device. In addition, the flow rate of the nutrient solution was measured through the discharge line in the piping toward the cultivation bed. This is used for the cultivation of various leafy vegetables.

The seedling root mass with the seedlings of each leafy vegetable (the seedlings that have passed through 10 days after sowing) is field planted on the above-mentioned cultivation bed, and 15 days after field planting (25 days after sowing) is cultivated with nutrient solution, and on the 16th day ( 26 days after sowing) were harvested, and the content of vitamin C was determined.

<Reference Example 1>

Spinach was grown under the above basic conditions, and the vitamin C content of the harvested spinach was measured.

The measuring method of the content of vitamin C is as follows.

From the spinach group cultivated under the same conditions, after derivatization with hydrazine, the ascorbic acid content measured by high-performance liquid chromatography was used as the vitamin C content after extracting four samples each three times.

<Examples 1 to 9>

Spinach was grown under the same conditions as in Reference Example 1, except that mannose was added to the nutrient solution so that the timing and amount of addition shown in Table 1 were used, and the vitamin C content was measured in the same manner. The results are shown in Table 1.

<Comparative Examples 1 to 3>

The procedure was the same as that of Reference Example 1, except that glucose (Comparative Example 1), fructose (Comparative Example 2), or sucrose (Comparative Example 3) was added to the nutrient solution instead of mannose at the timing and amount of addition shown in Table 1. Spinach was grown under the same conditions, and the vitamin C content was measured in the same way. The results are shown in Table 1.

The ratio of vitamin C content in Table 1 is based on the measurement results of the content of vitamin C in spinach harvested by cultivation under the basic conditions of Reference Example 1 as 100%. The ratio of the content of vitamin C in the spinach with respect to the content of Reference Example 1 represents the ratio of the vitamin C content.

[Table 1]

As shown in Table 1, compared with the spinach of Reference Example 1 to which mannose was not added, the vitamin C content of the spinach of Examples 1 to 9 that were cultivated with a nutrient solution containing mannose increased by 1.2 to 1.8 times. In addition, in Comparative Examples 1 to 3 to which other sugars, ie, glucose, fructose, and sucrose, were added, the content of vitamin C was not increased. As a result, according to the present invention, it was confirmed that the content of vitamin C in leafy vegetables increased.

<Reference Examples 2 to 4>

Scarlet beet, red beet, and red mustard, which are leafy vegetables other than spinach, were grown under the basic conditions described above, and the vitamin C content of each of the harvested leafy vegetables was measured. In addition, the vitamin C content of each reference example was calculated|required by the same method as the above-mentioned reference example 1.

<Examples 10 to 12>

Each leafy vegetable was cultivated under the same conditions as in Reference Examples 2 to 4 corresponding to the respective varieties, except that mannose was added to the nutrient solution so that the timing and amount of addition shown in Table 2 were the same as in Reference Example 1. Methods The content of vitamin C was determined. The results are shown in Table 2.

For the vitamin C content ratios in Table 2, the measurement results of the content of each vitamin C in the harvested red beet, red beet, and red mustard of Reference Examples 2 to 4 were taken as 100%, and the samples cultivated in Examples 10 to 12 were used. The vitamin C content ratio is shown as the ratio of the content of vitamin C in each of the red beet, the red beet, and the mustard with respect to the content of Reference Examples 2 to 4, respectively.

[Table 2]

As shown in Table 2, the content of vitamin C in each leafy vegetable of Examples 10 to 12 grown by supplying a nutrient solution containing mannose increased in comparison with that of each leafy vegetable of Reference Examples 2 to 4 to which mannose was not added. 1.2 to 1.3 times higher. In this way, according to the present invention, even in leafy vegetables other than spinach, it was confirmed that the vitamin C content was increased.

<Example 13>

Spinach was cultivated under the same conditions as in Reference Example 1, except that mannose was added to the nutrient solution so as to have the addition timing and addition amount shown in Table 3, and the vitamin C content was measured in the same manner. The results are shown in Table 3.

The results of the measurement of the vitamin C content ratio in Table 3 are based on the measurement results of the vitamin C content of spinach harvested by cultivation under the basic conditions of Reference Example 1 as 100.0%. The ratio of the content to the content of Reference Example 1 represents the vitamin C content ratio.

[table 3]

As shown in Table 3, it was confirmed that the increase in the vitamin C content in the spinach of Example 13 was small.

In addition, according to the above-mentioned Examples and the results of the experiments conducted by the present inventors, it was found that a cultivation example in which hemi-creatine, which is one of the sugars related to the ascorbic acid biosynthesis pathway, was added was also the vitamin C in the harvested spinach. No significant increase was found in the content. Thus, it became clear that among the monosaccharides in the ascorbic acid biosynthesis pathway, only mannose showed the effect of significantly increasing ascorbic acid. In addition, it became clear that even if sucrose, which is the most saccharide contained in spinach, was added, there was no effect of significantly increasing ascorbic acid.

In addition, the inventors of the present application measured the electrical conductivity and pH in each of the above-mentioned Reference Examples and Examples during the period from after sowing to harvest. Furthermore, when the variation values of conductivity and pH of each Example were compared with the variation values of conductivity and pH of Reference Example 1, there was no significant difference. From this, it was investigated that changes in the conductivity and pH of the nutrient solution caused by the addition of mannose did not stress the leafy vegetables to increase the ascorbic acid content of the leafy vegetables, but caused mannose to act on the leafy vegetables to increase the ascorbic acid content. Increases ascorbic acid.

Although this invention was demonstrated in detail using the specific aspect, it is clear for those skilled in the art that various changes can be added without deviating from the mind and range of this invention.

This application is based on Japanese Patent Application No. 2017-215651 filed on Nov. 8, 2017, the entirety of which is incorporated herein by reference.

Description of reference numerals

53…cultivation bed; 61…cultivation bed row; 62…cultivation bed group; 73…sub-tank; 86…mother tank; 90…meter; 91…spherical cock.

Claims (9)

1. a method for increasing the ascorbic acid content of leafy vegetables, supplying nutrient solution to cultivate leafy vegetables, it is characterized in that, The nutrient solution contains mannose, which circulates the nutrient solution, After the lateral roots of the leafy vegetables are formed or after the m-th day after the leafy vegetables are sown, the nutrient solution containing the mannose is supplied, wherein m is 5 or more, 0.15 mM or more and 5.0 mM or less of mannose is supplied as the nutrient solution after the lateral roots of the leafy vegetables are formed or after the m-th day after sowing and until the harvest day or until n days before the harvest day. The nutrient solution, where m is 10 or more and n is 1 or more. 2. the method for increasing the ascorbic acid content of leafy vegetables according to claim 1, is characterized in that, Leafy vegetables grown by supplying the nutrient solution containing the mannose are harvested. 3. the method for increasing the ascorbic acid content of leafy vegetables according to claim 1 and 2, is characterized in that, The nutrient solution also contains nitrate nitrogen, phosphoric acid and potassium. 4. the method for increasing the ascorbic acid content of leafy vegetables according to claim 1 and 2, is characterized in that, Leafy vegetables are cultivated by supplying the nutrient solution to the upper surface side of the bottom surface of the cultivation bed using a cultivation bed having a slope. 5. the method for increasing the ascorbic acid content of leafy vegetables according to claim 4, is characterized in that, The cultivation bed has a moisture space. 6. the method for increasing the ascorbic acid content of leafy vegetables according to claim 1 and 2, is characterized in that, A planting plate is arranged on the cultivation bed with a slope, and the planting plate is provided with a plurality of planting holes. The seedling root mass is placed on the cultivation bed through the planting hole, And it is a film hydroponics type hydroponics in which the nutrient solution is supplied to the upper surface side of the bottom surface of this cultivation bed, and leafy vegetables are cultivated. 7. the method for increasing the ascorbic acid content of leafy vegetables according to claim 6, is characterized in that, A plurality of ridges extending along the slope direction are arranged on the upper surface of the cultivation bed, The protruding strip is located below the planting hole, The convex strips are concave strips between each other, The seedling root mass is placed on the ridge, The nutrient solution is allowed to flow in the grooves. 8. the method for increasing the ascorbic acid content of leafy vegetables according to claim 6, is characterized in that, A hydrophilic sheet is arranged on the upper surface side of the bottom surface of the cultivation bed. 9. the method for increasing the ascorbic acid content of leafy vegetables according to claim 1 and 2, is characterized in that, The leafy vegetables are Sapinaceae, Cruciferae, Amaryllidaceae, Umbelliferae, Lamiaceae, Amaranthaceae, Compositae or Chenopodiaceae.

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