JP6051414B2 - Hydroponic cultivation method of low potassium leaf vegetable and low potassium leaf vegetable - Google Patents

Description

  The present invention relates to a method for hydroponics cultivation of low potassium vegetables and low potassium vegetables.

  Patients with kidney disease have a reduced ability to excrete potassium and sodium. Therefore, if these are ingested in large quantities, they cannot be excreted as urine and accumulate in the body. If such a situation is left as it is, hypertension in which the patient's blood pressure increases, cerebrovascular disorders (such as stroke), and heart disease (such as heart failure) may be induced.

  In order to reduce the blood potassium concentration of a kidney disease patient, for example, there is a treatment method using a drug such as a diuretic. Further, as another method for lowering blood potassium concentration in patients with kidney disease, dietary therapy with low potassium foods has attracted attention from the viewpoint of low side effects due to drugs and low cost.

  Various kinds of low potassium foods used for the treatment of patients with kidney disease have been studied. As one of them, low potassium vegetables by hydroponics and their cultivation methods have been studied conventionally (see, for example, Patent Document 1 or Patent Document 2).

In the hydroponic cultivation method disclosed in Patent Document 1 or Patent Document 2, the hydroponic cultivation period is divided into an initial period and a late period. In the initial stage, vegetables are cultivated with normal hydroponics fertilizers containing KNO _3, and in the latter stages, the vegetables are cultivated with hydroponics fertilizers containing HNO ₃ or NaNO ₃ instead of KNO ₃ . Moreover, pH of the hydroponics fertilizer is adjusted with NaOH over the whole cultivation period.

  Moreover, in order to prevent the increase in sodium content by NaOH used for pH adjustment in these hydroponic cultivation methods, it is easily absorbed by vegetables to the same extent as potassium, and for hydroponic cultivation containing a large amount of magnesium that contributes to the growth of vegetables. A hydroponics method using a fertilizer has been developed (see, for example, Patent Document 3).

  In the hydroponic method disclosed in Patent Document 3, the cultivation period is divided into an initial stage and a late stage. In the early stage, vegetables are cultivated with normal hydroponics fertilizers mainly composed of potassium, calcium, magnesium, phosphorus, and nitrogen. In the latter period, potassium, sodium, and calcium, magnesium, phosphorus, and nitrogen are not added. The vegetable is cultivated with the hydroponics fertilizer which has as a main component. When vegetables such as lettuce are cultivated by this hydroponics method, vegetables with a low total potassium content and sodium content can be cultivated.

JP 2008-61587 A JP 2011-36226 A JP 2012-183062 A

  The present invention provides a low-potassium vegetable having a small content of potassium and sodium in the whole vegetable and having a small content difference for each leaf, and a hydroponics method for cultivating the low-potassium vegetable.

  In the hydroponic cultivation method of low potassium vegetables of the present invention, the entire cultivation period from sowing to harvesting is divided into a first cultivation period, a second cultivation period following the first cultivation period, and a second cultivation according to the vegetables to be cultivated. Divide into the third cultivation period following the period. In the first cultivation period, vegetables are cultivated using hydroponics fertilizer containing potassium. In the 2nd cultivation period, vegetables are cultivated using the fertilizer for hydroponics which does not contain potassium substantially and contains magnesium. In the third cultivation period, vegetables are cultivated with water that does not contain fertilizer.

  Moreover, the low potassium vegetable of this invention has the inner leaf located in a center part, the outer leaf located in the outermost part, and the middle leaf located in the middle between an inner leaf and an outer leaf. And the difference between the potassium content of the inner leaf and the potassium content of the middle leaf is smaller than the difference between the potassium content of the middle leaf and the potassium content of the outer leaf.

  As described above, according to the present invention, the content of potassium and sodium in the whole vegetable is small, and the difference in the content of each leaf is small, and the hydroponics method for realizing such a vegetable. Can be provided.

The figure which shows each cultivation period in the hydroponic cultivation method by embodiment of this invention Diagram showing the relationship between inner leaves, middle leaves and outer leaves in lettuce The figure which shows content of potassium for every measurement position in the Example in embodiment of this invention, and each of the reference example 1. The figure which shows content of sodium for every measurement position in the Example in embodiment of this invention, and each of the reference example 1.

  Prior to the description of the embodiment of the present invention, problems in the conventional hydroponics method will be described. In the hydroponics method of patent document 3, the cultivation method is changed in the initial stage and the latter stage. Therefore, in the vegetables cultivated by this method, potassium content and sodium content may be different in the central leaf (inner leaf), intermediate leaf (medium leaf), and outer leaf (outer leaf). .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing each cultivation period in the hydroponics method according to the embodiment of the present invention. The low potassium vegetable in this Embodiment can be cultivated by performing hydroponics in the period shown in FIG. In addition, the vegetables in this Embodiment point out leafy vegetables, for example, lettuce, salad vegetables, sanchu, komatsuna, and cabbage. FIG. 2 is a diagram showing the relationship among the inner leaf 10, the middle leaf 20, and the outer leaf 30 in lettuce, which is an example of vegetables in the present embodiment. Hereinafter, the hydroponics method for low potassium vegetables according to the present embodiment will be described with reference to FIG.

  Initially, the cultivation period in the hydroponics method in this Embodiment is demonstrated. In the hydroponics method in this Embodiment, the 1st cultivation period Le, the 2nd cultivation period Lm, and the 3rd cultivation period Ll are set in the whole cultivation period L which shows the whole cultivation period of a low potassium vegetable. That is, according to the kind of vegetables (leafy vegetables), the total cultivation period L is the first cultivation period Le, the second cultivation period Lm following the first cultivation period Le, and the third cultivation following the second cultivation period Lm. Divide into periods Ll.

  The total cultivation period L is a period from seeding time A to harvest time E. In addition, the time length of the whole cultivation period L is almost decided by the kind of vegetable to grow, and can be preset according to the kind of vegetable. In addition, it turns out that the length of the whole cultivation period L is not influenced so much by the kind of fertilizer to be used. Therefore, according to the kind of vegetable, 1st cultivation period Le, 2nd cultivation period Lm, and 3rd cultivation period Ll can be preset.

  The first cultivation period Le is a period from seeding time A to fertilizer switching time C. The first cultivation period Le is preferably composed of a seedling raising period Le1 and a normal cultivation period Le2. That is, it is preferable to set the seedling raising period Le1 and the normal cultivation period Le2 following the seedling raising period Le1 as the first cultivation period Le. The seedling raising period Le1 is a period from seed germination until seedling growth is stabilized, and is a period from seeding time A to normal cultivation start time B. The seedling raising period Le1 is usually about two weeks regardless of the type of vegetable, but can be set as appropriate by experiments or the like. The normal cultivation period Le2 is a period from the normal cultivation start time B to the fertilizer switching time C.

  In addition, it is preferable to select only seedlings that have sufficiently grown in the seedling raising period Le1 and perform hydroponics of the present embodiment. If it does in this way, the vegetable which becomes further low potassium can be cultivated. Specifically, the size of vegetable seedlings (individuals) is measured at the start of normal cultivation B (at the end of the seedling raising period Le1), and only individuals that have grown to a predetermined size or larger are selected. It shifts to cultivation period Le2, and the individual which has grown only to a size smaller than a predetermined size is disposed.

  The second cultivation period Lm is a period from C at the time of fertilizer switching to D at the time of no fertilizer. At the time of fertilizer switching C, a predetermined period Lm retroactive from the non-fertilizer time D, which will be described later, is obtained by experiment, and is set as the start time of this period Lm.

  The third cultivation period Ll is a period from the non-fertilizer time D to the harvest time E. The non-fertilizer time D is a time point when a period in which fertilizers such as nitrogen and phosphorus as well as potassium are not given at all is started. Therefore, if the third cultivation period Ll becomes too long, the vegetables may wither due to physiological disorders such as potassium deficiency and calcium deficiency. Therefore, in the present embodiment, the third cultivation period Ll is obtained by experiment and set.

  In addition, it is desirable that the length of the third cultivation period Ll is about 10% of the length of the entire cultivation period L. Specifically, the third cultivation period Ll is desirably 5% or more and 10% or less of the entire cultivation period L. If the third cultivation period Ll is shorter than 5% of the total cultivation period L, the effect of reducing potassium is reduced, and if it is longer than 10%, physiological disorders are likely to occur.

  Moreover, it is desirable that the third cultivation period Ll is set shorter than the second cultivation period Lm, and the second cultivation period Lm is set shorter than the first cultivation period Le. By setting in this way, the individual can be grown sufficiently and the potassium content can be reduced.

  Then, the fertilizer used with the hydroponics method in this Embodiment is demonstrated. In the hydroponics method of this Embodiment, the fertilizer for hydroponics containing a different component is used by the 1st cultivation period Le and the 2nd cultivation period Lm. Specifically, the first hydroponics fertilizer is used in the first cultivation period Le, and the second hydroponics fertilizer is used in the second cultivation period Lm. Moreover, the water which does not contain a fertilizer is used in the 3rd cultivation period Ll.

  The first hydroponics fertilizer is a hydroponics fertilizer containing potassium. Specifically, it is a fertilizer for hydroponics mainly composed of potassium, calcium, magnesium, phosphorus, and nitrogen. By using this fertilizer for first hydroponics in the first cultivation period Le, the vegetables are germinated and grown normally.

  The 2nd hydroponics fertilizer is a hydroponics fertilizer which does not contain potassium substantially and contains magnesium. Specifically, hydroponics that does not contain potassium and sodium substantially, contains calcium, magnesium, phosphorus, and nitrogen as main components, and has a pH value of 5 to 9 when these main components are dissolved in water. Fertilizer for use. The absorption of magnesium in vegetables is comparable to the absorption of potassium and sodium. And in the second half of vegetable cultivation, magnesium greatly contributes to the growth of vegetables. Therefore, by using the second fertilizer for hydroponics containing magnesium instead of potassium, the vegetable grows normally even when the potassium content is reduced. In addition, “substantially not containing potassium and sodium” means that potassium and sodium in a negligible amount compared to the amount of other components at the time of preparation of fertilizer are allowed. For example, when tap water is used for diluting hydroponics fertilizer, sodium contained in tap water will be contained in hydroponics fertilizer, but it is used when diluting in this way. The amount contained in tap water is negligible.

  In the third cultivation period Ll, it is preferable to cultivate with pure water that does not completely contain potassium or sodium, but tap water may be used.

  By using the water which does not contain a fertilizer in the 3rd cultivation period L1, potassium and sodium contained in vegetables melt into water and content of the whole vegetables falls. Moreover, potassium and sodium move (flow) from the outer leaf 30 shown in FIG. 2 to the inner leaf 10 through this water, and the difference in the content of potassium and sodium in the inner leaf 10, the middle leaf 20, and the outer leaf 30 is different. Get smaller. Here, the inner leaf 10 is a leaf located at the center of the individual vegetable. The outer leaf 30 is a leaf located at the outermost part of the vegetable individual. The middle leaf 20 is a leaf of the middle part of the vegetable individual (center and outermost middle), and is located between the inner leaf 10 and the outer leaf 30.

  In general, leafy vegetables grow repeatedly by germinating from seeds and opening a foliage (cotyledon), then the main leaf comes out from the center and the next main leaf comes out from the center of the main leaf one after another. Particularly in leafy vegetables such as lettuce and cabbage, the core extends to the center of the sphere, and the outer leaf 30 extends from the position closest to the root at the bottom of the core. The inner leaf 10 is the youngest leaf extending from the tip of the core. The middle leaf 20 extends from the center position in the direction in which the core extends. Each leaf extends outward from the core, and the middle leaf 20 is obtained by counting the number of sheets extending from the core between the inner leaf 10 and the outer leaf 30 when the headed leafy vegetables are cut vertically. Can be identified. Even in leaf vegetables such as Komatsuna, which do not have heads, the outer leaf 30 extends from a position closest to the root when the leaf vegetables are cut vertically. The inner leaf 10 extends from the center of the individual. The middle leaf 20 can be identified by counting the number of sheets extending between the inner leaf 10 and the outer leaf 30.

  Subsequently, a specific example in the present embodiment will be described. That is, using the hydroponics method of the present embodiment, lettuce is cultivated, and the potassium and sodium contents of the inner leaf 10, the middle leaf 20, and the outer leaf 30, and the potassium and sodium content of the whole lettuce. The results of measuring are described. In addition, this invention is not limited by the following examples.

  The composition of the stock solutions of the first and second hydroponics fertilizers is as shown in (Table 1). In hydroponics, this stock solution is diluted with water and used.

  In addition, as a comparison object of a present Example, the same kind of lettuce is cultivated without providing the 3rd cultivation period Ll in FIG. Hereinafter, it is referred to as “Reference Example 1”. Moreover, the same kind of lettuce is cultivated by a general hydroponics method. Hereinafter, it is referred to as “Reference Example 2”. And also about the reference examples 1 and 2, each potassium and sodium content of an inner leaf, a middle leaf, and an outer leaf, and the content of potassium and sodium of the whole lettuce are measured. Based on these results, the effect of differences in hydroponics fertilizers on potassium and sodium contents is investigated. The following experiments are average values obtained three times or more under the same conditions. In addition, in the cultivation of a present Example, the reference example 1, and the reference example 2, the temperature of a cultivation room is controlled to 17-23 degreeC.

  In the seedling raising period Le1 of the present embodiment, lettuce seeds are germinated to grow seedlings. Specifically, first, lettuce seeds are soaked in a disinfecting solution obtained by diluting an aqueous sodium hypochlorite solution 10 times, and then washed. A plurality of the seeds washed in this way are put together in a sponge-like lock sheet, and the lock sheet is immersed in a hydroponic liquid containing the first hydroponics fertilizer. Then, the seeds are germinated in the dark state. After germination, the seedlings are transferred to a bright environment, and the germinated seedlings are grown as they are in the hydroponic solution containing the first hydroponics fertilizer during the remaining seedling period Le1.

  In the normal cultivation period Le2 of the present embodiment, seedlings with good growth are selected from the seedlings grown in the seedling raising period Le1, and each seedling is wrapped with a sponge and the first hydroponics fertilizer is used. Transplant to hydroponic solution and cultivate.

  In the 2nd cultivation period Lm of a present Example, a seedling is transplanted and cultivated to the hydroponics liquid containing the fertilizer for 2nd hydroponics which does not contain potassium and sodium. Moreover, in the 3rd cultivation period Ll of a present Example, a seedling is transplanted and cultivated in the water which does not contain the fertilizer. Then, lettuce is harvested at harvest time E.

  In the hydroponics of Reference Example 1, the entire cultivation period L is divided into two periods, an initial cultivation period and a final cultivation period. The initial cultivation period of Reference Example 1 is the same as the first cultivation period Le of the hydroponic cultivation method of this example, and the final cultivation period of Reference Example 1 is the second cultivation period of the hydroponic cultivation method of this example. This corresponds to a period combining Lm and the third cultivation period Ll. Moreover, in Reference Example 1, lettuce is cultivated using the first hydroponics fertilizer in the initial cultivation period and the second hydroponics fertilizer in the final cultivation period.

  In the hydroponics of Reference Example 2, lettuce is cultivated using the first hydroponics fertilizer during the entire cultivation period.

  As the potassium and sodium contents contained in the harvested lettuce in each of this example, reference example 1 and reference example 2, the potassium content per 100 g of fresh weight is measured using an atomic absorption spectrometer. Specifically, first, the total fresh weight of each lettuce is measured immediately after harvesting. Then, lettuce is the inner leaf, the middle portion of the inner leaf and the middle leaf (hereinafter referred to as “inner and middle leaf”), the middle leaf, the middle portion of the middle leaf and the outer leaf (hereinafter referred to as “middle and outer leaf”), and the outer leaf. Divide into five measurement positions and measure the fresh weight of the leaves at each measurement position. In addition, about lettuce cultivated by the normal method, content, such as the fresh weight and potassium of a leaf for every measurement position, is assumed on the assumption that it is uniform as a whole. Subsequently, the whole lettuce or the lettuce divided for each leaf is dried in a dryer at 80 ° C. for 72 hours or more, and then further dried at 80 ° C. for 48 hours to obtain a dry matter. After the obtained dry matter is pulverized, the pulverized dry matter is dry-ashed at 550 ° C. for 6 hours. The eluted components are extracted from the obtained ash using an aqueous nitric acid solution having a concentration of 1 mol / L. Then, the contents of potassium and sodium contained in the extracted liquid are measured with an atomic absorption spectrometer. By converting the content thus obtained into a ratio per fresh weight, the contents of potassium and sodium per 100 g of fresh weight are measured. The results are shown in Table 2 and FIGS. 3A and 3B.

  (Table 2) has shown the result of having measured the content of potassium and sodium of the whole lettuce of each of a present Example, the reference example 1, and the reference example 2. FIG.

  FIG. 3A shows the potassium content at each measurement position in this example and Reference Example 1 with the measurement position on the horizontal axis and the potassium content per 100 g of fresh weight on the vertical axis. In the lettuce cultivated by the hydroponics method of Reference Example 1, it can be seen that there is a large difference in potassium content between the inner leaf and the outer leaf, and that there is a rapid increase from the inner middle leaf to the middle leaf. On the other hand, in the lettuce cultivated by the hydroponics method of the present example, the difference in potassium content between the inner leaf and the outer leaf is smaller than that in Reference Example 1, and it increases gently from the inner leaf to the middle and outer leaf. ing.

  Specifically, in the lettuce cultivated by the hydroponics method of this example, the difference between the potassium content of the inner leaf and the potassium content of the middle leaf is the difference between the potassium content of the middle leaf and the potassium content of the outer leaf. Smaller than. In contrast, in the lettuce cultivated by the hydroponics method of Reference Example 1, the difference between the potassium content of the inner leaf and the potassium content of the middle leaf is the difference between the potassium content of the middle leaf and the potassium content of the outer leaf. Greater than the difference. Moreover, the difference between the potassium content of the inner leaf of the lettuce of this example and the potassium content of the outer leaf is more than the difference between the potassium content of the inner leaf of the lettuce of Reference Example 1 and the potassium content of the outer leaf. small.

  FIG. 3B shows the sodium content at each measurement position in this example and Reference Example 1 with the measurement position on the horizontal axis and the sodium content per 100 g of fresh weight on the vertical axis. The difference in sodium content between the inner leaf and the outer leaf is not significantly different between the two cultivation methods. However, at all measurement positions, the sodium content of the lettuce of this example is smaller than the sodium content of the lettuce of Reference Example 1. Moreover, the difference between the sodium content of the inner leaf of the lettuce of this example and the sodium content of the outer leaf is more than the difference between the sodium content of the inner leaf of the lettuce of Reference Example 1 and the sodium content of the outer leaf. Somewhat small.

  As apparent from Table 2 and FIGS. 3A and 3B, if lettuce is cultivated by the hydroponic cultivation method of the present embodiment, the total amount of potassium and the amount of potassium for each lettuce and parts are compared with those of the conventional hydroponic cultivation method. There is little sodium content, and the difference of the content of potassium and sodium for every leaf of lettuce is small.

  In this example, Reference Example 1 and Reference Example 2, all the hydroponics fertilizers used did not contain sodium, and no sodium was intentionally added to the hydroponic liquid. Nevertheless, sodium has been detected in the harvested lettuce leaves. This is considered to be due to the use of tap water when diluting the hydroponics fertilizer. That is, it is considered that the cause is that the sodium chlorite (NaClO) for sterilization added to the tap water is absorbed by lettuce.

  Since the low potassium vegetable according to the present invention has a low content of potassium and sodium, it is possible to provide a vegetable that can be safely consumed by patients with kidney disease.

10 inner leaf 20 middle leaf 30 outer leaf

Claims (6)

Depending on the type of leaf vegetable , the total cultivation period from sowing to harvesting is the first cultivation period, the second cultivation period following the first cultivation period, and the third cultivation period following the second cultivation period , In the hydroponics method divided into three periods ,
In the first cultivation period, cultivating the leaf vegetables using a first hydroponics fertilizer containing potassium;
In the second cultivation period, the step of cultivating the leaf vegetable using a second hydroponics fertilizer containing substantially no potassium and magnesium;
Cultivating the leafy vegetables using water that is substantially free of potassium without using the first hydroponics fertilizer and the second hydroponics fertilizer in the third cultivation period. ,
Hydroponic cultivation method of low potassium leaf vegetable . The third cultivation period is set shorter than the second cultivation period, and the second cultivation period is set shorter than the first cultivation period.
The hydroponic cultivation method of the low potassium leaf vegetable of Claim 1. The third cultivation period is set to a length of 5% or more and 10% or less of the total cultivation period.
The hydroponic cultivation method of the low potassium leaf vegetable as described in any one of Claims 1 and 2. The first cultivation period is divided into a seedling period and a normal cultivation period following the seedling period,
At the end of the seedling period, the size of the leaf vegetable is measured , and the leaf vegetable growing to a predetermined size or more is cultivated in the normal cultivation period.
The hydroponic cultivation method of the low potassium leaf vegetable as described in any one of Claim 1 to 3. The leaf vegetable is either lettuce, salad vegetable, sanchu, komatsuna or cabbage,
When the leafy vegetables are divided into an inner leaf located at the center, an outer leaf located at the outermost part, and a middle leaf located between the inner leaf and the outer leaf,
In the leafy vegetables harvested after the third cultivation period, the difference between the potassium content of the inner leaf and the potassium content of the middle leaf is based on the difference between the potassium content of the middle leaf and the potassium content of the outer leaf. Is also small,
The hydroponic cultivation method of the low potassium leaf vegetable as described in any one of Claim 1 to 3. And leaves inner centrally located either the outer leaves located outermost, and middle lobe located in the middle between the outer leaf and the inner leaf, Ru with lettuce, lettuce, lettuce, of Komatsuna or cabbage In
The difference between the potassium content of the inner leaf and the potassium content of the middle leaf is smaller than the difference between the potassium content of the middle leaf and the potassium content of the outer leaf,
Low potassium leaf vegetable .

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