JP6534108B2 - Low potassium leafy vegetables - Google Patents

Description

  The present invention relates to low potassium leafy vegetables.

  Patients with kidney disease have a reduced ability to excrete potassium and sodium. Therefore, if a large amount of these is ingested, it can not be excreted as urine and will accumulate in the body. If such a situation is left as it is, it may lead to hypertension in which the patient's blood pressure is high, and resulting cerebrovascular disorder (such as stroke) and heart disease (such as heart failure).

  There are methods of treatment with drugs such as, for example, diuretics to reduce the blood potassium concentration in renal disease patients. In addition, as another method for lowering the blood potassium concentration in renal disease patients, a diet using a low potassium food is attracting attention from the viewpoint of low side effects caused by drugs and low cost.

  Various low potassium foods used for treatment of patients with kidney disease have been conventionally studied. As one of them, a low potassium vegetable by hydroponic culture and its cultivation method have been conventionally studied (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 two, an early phase and a late phase. In the early stage, vegetables are grown with ordinary hydroponic fertilizers containing KNO 3, and in the later stage the vegetables are grown with hydroponic fertilizers containing HNO 3 or NaNO 3 instead of KNO 3. In addition, the pH of the hydroponic fertilizer is adjusted with NaOH over the entire cultivation period.

  Moreover, in order to prevent the rise of sodium content by NaOH used for pH adjustment in these hydroponic cultivation methods, it is easy to be absorbed by vegetables to the same extent as potassium, and for hydroponic cultivation containing much magnesium contributing to the growth of vegetables A hydroponic cultivation method using fertilizer has been developed (see, for example, Patent Document 3).

  In the water culture method disclosed in Patent Document 3, the cultivation period is divided into an early period and a late period. Vegetables are grown initially with common hydroponic fertilizers based on potassium, calcium, magnesium, phosphorus, and nitrogen, and potassium and sodium are not blended in the later stage, calcium, magnesium, phosphorus, and nitrogen are used. Cultivate the vegetables with hydroponic fertilizers whose main ingredient is When vegetables such as lettuce are cultivated by this hydroponic cultivation method, vegetables having a low potassium content and a low sodium content can be grown.

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

  The present invention provides low potassium leafy vegetables with a low content of potassium.

  The low potassium leaf vegetable of the present disclosure has 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. 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. Also, the potassium content of the inner leaves is less than the potassium content of the middle and outer leaves.

  As described above, according to the present disclosure, it is possible to provide a low potassium leaf vegetable having a low content of potassium.

Diagram showing each cultivation period in the water culture method according to the embodiment of the present invention Diagram showing the relationship between inner leaves, middle leaves and outer leaves in lettuce The figure which shows the content of the potassium for every measurement position in each of the example in the embodiment of the present invention, and the reference example 1. The figure which shows the content of the sodium for every measurement position in each of the example in the embodiment of the present invention, and the reference example 1.

  Prior to the description of the embodiment of the present invention, the problems in the conventional hydroponic cultivation method will be described. In the hydroponic cultivation method of patent document 3, the cultivation method is changed in the early stage and the late stage. Therefore, in vegetables grown by this method, the potassium content and sodium content may differ between the central leaf (inner leaf), middle leaf (middle leaf), and outer leaf (outer leaf). .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a view showing each cultivation period in the water culture method according to the embodiment of the present invention. The low potassium vegetables in the present embodiment can be cultivated by performing hydroponic cultivation in the period shown in FIG. The vegetables in the present embodiment refer to leafy vegetables such as lettuce, salads, sachu, Komatsuna, and cabbage. FIG. 2 is a view showing the relationship between the inner leaf 10, the middle leaf 20, and the outer leaf 30 in lettuce which is an example of a vegetable according to the present embodiment. Hereinafter, the hydroponic cultivation method of the low potassium vegetable by this embodiment is explained, referring to FIG.

  First, the cultivation period in the hydroponic cultivation method in the present embodiment will be described. In the hydroponic cultivation method in the present embodiment, a first cultivation period Le, a second cultivation period Lm, and a third cultivation period Ll are set in the entire cultivation period L showing the whole cultivation period of the low potassium vegetable. That is, according to the type of vegetables (leaf 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 period Ll.

  The total cultivation period L is a period from seeding time A to harvesting time E. The temporal length of the entire cultivation period L is substantially determined by the type of vegetable to be grown, and can be set in advance according to the type of vegetable. In addition, it is known that the length of the whole cultivation period L is not much influenced by the type of fertilizer used. Therefore, according to the kind of vegetables, 1st cultivation period Le, 2nd cultivation period Lm, and 3rd cultivation period Ll can be set up beforehand.

  The first cultivation period Le is a period from seeding time A to fertilizer switching time C. It is preferable that the first cultivation period Le is constituted by a nursery period Le1 and a normal cultivation period Le2. That is, it is preferable to set a seedling raising period Le1 and a 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 germination of seeds to stabilization of growth of seedlings, and is a period from seeding time A to normal cultivation start time B. Although the nursery period Le1 is usually about two weeks regardless of the type of vegetable, it can be set appropriately by experiment 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 the seedlings grown sufficiently in the nursery period Le1 and to carry out the hydroponic cultivation of the present embodiment. By doing this, it is possible to cultivate vegetables that are further reduced in potassium. Specifically, the sizes of the seedlings (individuals) of the vegetables are respectively measured at the normal cultivation start time B (at the end of the seedling raising period Le1), and only the individuals growing to a predetermined size or larger are selected to It transfers to cultivation period Le2, and discards the individual | organism | solid which has grown to less than predetermined size.

  The second cultivation period Lm is a period from the time C at which the fertilizer is switched to the time D at which no fertilizer occurs. The fertilizer switching time C is determined as a start time of this period Lm by determining a predetermined period Lm, which goes back from the fertilizer-free time D to be described later.

  The third cultivation period Ll is a period from the no fertilizer change D to the harvest time E. At the time of fertilizer-free time D, it is the time to start a period where no fertilizer such as nitrogen or phosphorus is given as well as potassium. Therefore, if the third cultivation period Ll is too long, vegetables may die due to physiological disorders such as potassium deficiency and calcium deficiency. Therefore, in the present embodiment, the third cultivation period Ll is determined by experiment.

  In addition, as for the length of 3rd cultivation period Ll, it is desirable that it is about 10% of the length of all cultivation periods L. Specifically, it is desirable that the third cultivation period Ll be 5% or more and 10% or less of the total cultivation period L. If the third cultivation period Ll is shorter than 5% of the total cultivation period L, the effect of reducing potassium decreases, and if it is longer than 10%, physiological disorders are likely to occur.

  In addition, it is desirable to set the third cultivation period Ll shorter than the second cultivation period Lm and set the second cultivation period Lm shorter than the first cultivation period Le. By setting in this manner, an individual can be sufficiently grown and the potassium content can be reduced.

  Then, the fertilizer used by the hydroponic cultivation method in this Embodiment is demonstrated. In the hydroponic cultivation method of this embodiment, the hydroponic cultivation fertilizer containing different components is used in the first cultivation period Le and the second cultivation period Lm. Specifically, in the first cultivation period Le, the first hydroponic cultivation fertilizer is used, and in the second cultivation period Lm, the second hydroponic cultivation fertilizer is used. In the third cultivation period Ll, water containing no fertilizer is used.

  The first hydroponic fertilizer is a hydroponic fertilizer containing potassium. Specifically, it is a water culture fertilizer containing potassium, calcium, magnesium, phosphorus and nitrogen as main components. By using this first hydroponic fertilizer for the first cultivation period Le, the vegetables germinate normally and grow.

  The second hydroponic fertilizer is a hydroponic fertilizer which contains substantially no potassium and contains magnesium. Specifically, hydroponic culture which contains calcium, magnesium, phosphorus and nitrogen as main components and does not contain potassium and sodium substantially, and the pH value becomes 5 to 9 when these main components are dissolved in water It is fertilizer for. The absorbency of magnesium in vegetables is comparable to that of potassium and sodium. And, in the latter half of vegetable cultivation, magnesium greatly contributes to the growth of vegetables. Therefore, by using a second hydroponic fertilizer containing magnesium instead of potassium, the vegetables grow normally even with a reduced potassium content. In addition, "it does not mix | blend potassium and sodium substantially" means that the mixing | blending of the potassium and sodium of the negligible extent compared with the amount of other components at the time of preparation of a fertilizer is accept | permitted. For example, when using tap water for dilution of hydroponic fertilizer, sodium contained in the tap water will be included in hydroponic 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 completely free of potassium and sodium, but tap water may be used.

  By using water containing no fertilizer in the third cultivation period Ll, potassium and sodium contained in the vegetables dissolve in the water and the content of the whole vegetables decreases. Also, potassium and sodium move (flush) from the outer leaf 30 shown in FIG. 2 to the inner leaf 10 through this water, and the difference in the potassium and sodium contents of the inner leaf 10, middle leaf 20 and outer leaf 30 It becomes smaller. Here, the inner leaf 10 is a leaf located at the center of a vegetable individual. Outer leaf 30 is a leaf located at the outermost part of the individual of vegetables. The middle leaf 20 is a leaf in the middle part (middle part between the center part and the outermost part) of the individual of the vegetable, and is located in the middle between the inner leaf 10 and the outer leaf 30.

  Generally, in leafy vegetables, after sprouting from a seed and opening of a bifoliate (cotyledon), true leaves come out from the center, and the next true leaves come out from the center of the true leaf one after another repeatedly and grow. In particular, in the case of leafy vegetables such as lettuce and cabbage, the core extends to the center of the bulb, and the outer leaf 30 extends from the position closest to the root below the core. The inner leaf 10 is the youngest leaf extending from the tip of the core. The middle leaf 20 extends from the central position in the direction in which the core extends. Each leaf extends outward from the core, and the middle leaf 20 counts the number of sheets extending from the core between the inner leaf 10 and the outer leaf 30 when the individual of the leafy vegetables which has been headed is cut longitudinally. It can be identified. The outer leaf 30 extends from the position closest to the root when the leaf vegetables are cut longitudinally, even with non-heading leaf vegetables such as komatsuna. 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, specific examples in the present embodiment will be described. That is, lettuce is grown using the hydroponic cultivation method of the present embodiment, and the respective potassium and sodium contents of the inner leaf 10, the middle leaf 20 and the outer leaf 30 and the potassium and sodium contents of the whole lettuce Explain the result of measuring. Note that the present invention is not limited by the following examples.

  The compositions of the stock solutions of the first and second hydroponic fertilizers are as shown in (Table 1). In addition, in the case of hydroponic cultivation, this undiluted | stock solution is diluted with water and used.

  In addition, the lettuce of the same kind is grown without providing the 3rd cultivation period Ll in FIG. 1 as comparison object of a present Example. Hereinafter, it is referred to as "Reference Example 1". Also, the same kind of lettuce is cultivated by a general hydroponic cultivation method. Hereinafter, it is referred to as "Reference Example 2". Then, the potassium and sodium contents of the inner leaf, the middle leaf and the outer leaf of each of Reference Examples 1 and 2 and the potassium and sodium contents of the whole lettuce are measured. Based on these results, the influence of the difference between the hydroponic fertilizers on the potassium and sodium content is investigated. Moreover, the following experiments are average values performed three or more times under the same conditions. In addition, in cultivation of a present Example, the reference example 1, and the reference example 2, the temperature of the cultivation room is controlled to 17-23 degreeC.

  In the seedling raising period Le1 of the present embodiment, a seed of lettuce is germinated to grow a seedling. Specifically, first, lettuce seeds are soaked for 30 minutes in a disinfecting solution in which a sodium hypochlorite aqueous solution is diluted 10-fold and then washed. A plurality of seeds washed in this manner are collected together and embedded in a sponge-like lock sheet, and the lock sheet is immersed in a water culture solution containing a first hydroponic fertilizer. Then, the seeds are germinated in the dark. After germination, the seedlings are transferred to a bright environment, and the sprouted seedlings are grown in the water culture medium containing the first hydroponic fertilizer as it is during the remaining seedling raising period Le1.

  In the normal cultivation period Le2 of the present embodiment, seedlings having good growth are selected from among seedlings grown in the nursery period Le1, and those seedlings are wrapped by sponge one by one to use the first hydroponic fertilizer. Transplant in water culture medium and cultivate.

  In the second cultivation period Lm of this embodiment, the seedlings are transplanted and cultivated in a water culture solution containing a second water culture fertilizer containing no potassium and sodium. In the third cultivation period Ll of the present embodiment, the seedlings are transplanted and cultivated in water not containing fertilizer. And at harvest time E, harvest lettuce.

  In the hydroponic cultivation of the reference example 1, the total cultivation period L is divided into two periods of an initial cultivation period and a final cultivation period. The initial cultivation period of the reference example 1 is the same as the first cultivation period Le of the hydroponic cultivation method of the present embodiment, and the final cultivation period of the reference example 1 is the second cultivation period of the hydroponic cultivation method of the present embodiment It corresponds to the period which combined Lm and the 3rd cultivation period Ll. Moreover, in the reference example 1, lettuce is grown using the first hydroponic cultivation fertilizer in the initial cultivation period and the second hydroponic cultivation fertilizer in the final cultivation period.

  In the hydroponic cultivation of the reference example 2, lettuce is grown using the first hydroponic cultivation fertilizer for the entire cultivation period.

  As content of potassium and sodium contained in the harvested lettuce of 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 whole fresh weight is measured immediately after harvesting each lettuce. Thereafter, lettuce is an inner leaf, an intermediate portion between inner and middle leaves (hereinafter referred to as "inner middle leaf"), a middle leaf, an intermediate portion between middle and outer leaves (hereinafter referred to as "middle outer leaf"), an outer leaf Divide into five measurement positions and measure the fresh weight of the leaves at each measurement position. In addition, about the lettuce grown by the normal method, content of fresh weight of a leaf, potassium, etc. for every measurement position is not measured on the assumption that it is uniform in the whole. Subsequently, the whole lettuce or the lettuce divided into leaves is dried in an oven at 80 ° C. for 72 hours or more, and then dried further at 80 ° C. for 48 hours to obtain a dry matter. After grinding the resulting dry matter, the dry matter is dry-ashed at 550 ° C. for 6 hours. The eluted components are extracted from the obtained ash using a 1 mol / L nitric acid aqueous solution. Then, the contents of potassium and sodium contained in the extracted solution are measured by an atomic absorption spectrometer. The content of potassium and sodium per 100 g of fresh weight is measured by converting the content thus obtained to the ratio of fresh weight. The results are shown in Table 2 and FIGS. 3A and 3B.

  Table 2 shows the results of measuring the potassium and sodium contents of the whole lettuce in each of this example, reference example 1 and reference example 2.

  FIG. 3A shows the potassium content for 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 grown by the hydroponic cultivation method of Reference Example 1, it can be seen that the difference in potassium content between the inner and outer leaves is large, and increases rapidly from the inner middle leaf to the middle leaf. On the other hand, in the lettuce cultivated by the hydroponic cultivation method of this example, the difference in potassium content between the inner and outer leaves is smaller than that in Reference Example 1, and gradually increases from the inner to middle and outer leaves. ing.

  Specifically, in lettuce grown by the water culture 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 Less than. On the other hand, in lettuce grown by the hydroponic cultivation 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 the present example and the potassium content of the outer leaf is higher 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 for 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 and outer leaves was 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 and the sodium content of the outer leaf of the lettuce of the present example is more than the difference between the sodium content of the inner leaf and the sodium content of the outer leaf of the lettuce of Reference Example 1. Slightly smaller.

  As apparent from (Table 2) and FIGS. 3A and 3B, if lettuce are grown by the water culture method of the present embodiment, potassium and every part of lettuce are compared with the conventional water culture method. The sodium content is low, and the difference in potassium and sodium content between lettuce leaves is small.

  In addition, in the present Example, the reference example 1, and the reference example 2, all the used fertilizers for hydroponic cultivation do not contain sodium, and sodium was not intentionally added also to the hydroponic solution. Nevertheless, sodium is detected from the harvested lettuce leaves. This is considered to be caused by using tap water when diluting the hydroponic fertilizer. That is, it is considered that the cause is that the sterilizing sodium hypochlorite (NaClO) added to the tap water is absorbed by lettuce.

  Since the low potassium vegetables according to the present invention have low contents of potassium and sodium, it is possible to provide vegetables which can be safely consumed by renal disease patients.

10 inner leaves 20 middle leaves 30 outer leaves

Claims (1)

Any of lettuce, salad, sachu, satchu, komatsuna or cabbage comprising 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 low potassium leafy vegetables of
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,
The potassium content of the inner leaf is less than the potassium content of the middle leaf and the outer leaf,
Low potassium leafy vegetables.

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