JP4792587B2 - Low potassium spinach and its cultivation method - Google Patents

Description

The present invention relates to a cultivation method with low potassium content in leaf vegetable agricultural products, specifically spinach.

The number of dialysis patients with kidney disease is about 250,000 at the end of 2004, about 2.5 times that of 1990, and the number is rapidly increasing. Since kidney disease has few subjective symptoms, it is estimated that there are millions of people including the reserve group, and further increase in dialysis patients is expected in the future. Furthermore, given that the number one primary disease leading to dialysis is diabetes, which is very common in Japanese, it is easy to imagine that the number of dialysis patients in Japan will continue to increase. (Non-Patent Document 1)

Because dialysis patients with kidney disease cannot excrete enough potassium from the body, heart failure may occur due to arrhythmia if potassium intake is not restricted. Therefore, renal dialysis patients are limited to a daily potassium intake of 1500-2000 mg. Because the vegetables we eat on a daily basis also contain a lot of potassium, kidney dialysis patients can't eat the vegetables rawly, but they can eat it by removing the potassium by exposing them to water or boiling them. There is a need to. (Non-Patent Document 2)

Considering the dietary habits of dialysis patients with kidney disease, vegetables with as little potassium content as possible contained in a constant fresh weight are desired. On the other hand, potassium is one of the essential elements of plants, and the physiological function of potassium is to maintain the protoplasmic structure for normal metabolism in the cell and to control pH and osmotic pressure. It is thought to be working. (Non-patent document 3) Therefore, it is considered that excessively reducing potassium in the plant body makes it impossible to maintain the homeostasis in the plant body and causes a growth disorder. The present invention is one-third to one-quarter of the one cultivated by the conventional cultivation method while maintaining the homeostasis in the plant, showing the same growth as normal cultivation without causing a growth disorder due to potassium deficiency. It is a cultivation method of spinach that is suppressed from 2300 μg to 1800 μg per 1 g of fresh weight.

In general, methods for changing the functionality of agricultural products include cross breeding and genetic engineering techniques, but it takes time to change the functionality of each method, and for genetically modified crops, there are concerns about safety. Is currently not accepted by consumers. Unlike the current methods, the present invention controls the potassium content by controlling the cultivation environment.
Japan Dialysis Medical Society 2005, Illustrated Current Status of Chronic Dialysis Therapy in Japan, as of December 31, 2004, Japan Dialysis Medical Society Statistical Investigation Committee, Tokyo, 3-12. Deura Terukuni 2002, A book that shows renal failure-Dietary therapy delays dialysis, Nihon Crihonsha, Tokyo. Yamazaki Kou, Sugiyama Tatsuo, Takahashi Eiichi, Kanno Michio, Tashino Toshiaki, Aso Shohei 1993, Plant Nutrition and Fertilizer Science, Asakura Shoten, Tokyo, 73-101.

Patients with kidney disease have restricted potassium intake. Because the vegetables we eat on a daily basis also contain a lot of potassium, kidney dialysis patients can't eat the vegetables rawly, but they can eat it by removing the potassium by exposing them to water or boiling them. There is a need to. However, using methods that expose or boil vegetables can reduce the potassium content per fresh weight, but not completely leaching potassium, but only removing some potassium. In addition, nutrients and nutrients other than potassium may be leached or decomposed. Considering the diet of kidney disease dialysis patients, vegetables with as little potassium content as possible contained in a constant fresh weight are desired.

In general, methods for changing the functionality of agricultural products include cross breeding and genetic recombination techniques, but they are not accepted in the market.

The present invention has been made in view of the present situation, and by adjusting the amount of potassium fertilization in the cultivation stage, the potassium of the edible part of leafy vegetables is affected without affecting the growth of the edible part of leafy vegetables. The purpose is to reduce the content.

The inventor conducted intensive research to solve the above-mentioned problems, and used spinach with a high potassium content in leafy vegetables as a model plant. By adjusting the potassium concentration of the medium during the cultivation period, Compared with spinach cultivated by the method, growth restriction due to potassium restriction does not occur, but the potassium content per unit fresh weight in the edible part at the time of harvest is 1/3 to 1/1 of that cultivated by conventional cultivation methods It came to establish the cultivation method restrained from 2300μg to 1800μg per 1g fresh weight.

That is, the present invention solved the problem by the following procedure.
(1) A method for cultivating spinach with low potassium content at the time of harvest while maintaining the growth of edible parts without causing potassium deficiency disorder (2) Water that can easily change the nutrient composition in the culture medium Cultivate spinach as described in (1) by adding the same concentration of HNO ₃ in place of KNO ₃ which is the potassium element in the hydroponics, and adjusting the pH to 6.0-6.5 using NaOH. (3) In order to reduce the potassium content at harvesting efficiently while maintaining the growth of spinach, KNO without reducing the potassium content in the hydroponics during the first 3 weeks of the cultivation period of 5 weeks ₃ after cultivation, and by adding the same concentration of HNO ₃ instead of KNO ₃ and reducing the potassium content in the hydroponic liquid after the 4th week, the potassium content was cultivated by conventional cultivation methods. 3 to 1/4, spinach as described in (1) How to grow

By cultivating leafy vegetables with low potassium content according to the present invention, it greatly contributes to the improvement of dietary habits of dialysis patients with kidney disease. In other words, dialysis patients with kidney disease cannot fully drain potassium in the body, and heart failure may occur due to arrhythmia unless potassium intake is restricted. Therefore, renal dialysis patients are limited to a daily potassium intake of 1500-2000 mg. The leafy vegetables we eat on a daily basis also contain a lot of potassium, so kidney dialysis patients can't eat raw, but need to take it by removing the potassium by exposure to water or boiled water There is. Leafy vegetables contain many nutrients, mainly vitamins, and some of these nutrients contain solutes and decomposes when exposed to water or boiled. In addition, it is not possible to completely leaching potassium by just exposing it to water or boiling it, but it is possible to remove some potassium. According to the present invention, the potassium content per unit fresh weight of the edible part at the time of harvest can be reduced from 2300 μg to 1800 μg per 1 g of fresh weight, which is 1/3 to 1/4 of that cultivated by the conventional cultivation method. Even dialysis patients can take more leafy vegetables than before, and can eat nutrients efficiently by being able to eat raw.

In this invention, it is suitable to grow using the hydroponic method which can change easily the nutrient composition of the culture medium during a cultivation period. That is, the leaf vegetable agricultural product cultivation facility used in the present invention can be said to be a plant (vegetable) factory facility in which the cultivation environment can be completely controlled.

After spinach seed germination, it is cultivated for 5 weeks by hydroponics. For 3 weeks after transplantation, since it requires potassium for growth, it is cultivated in a hydroponic solution containing potassium as shown in Table 1. From the 4th week onwards, KNO ₃ in the hydroponic solution composition is changed to HNO ₃ of the same concentration and potassium is Change to a hydroponic solution that does not contain the soil. Adjust the pH of the hydroponics to pH 6.5 using 0.1N NaOH.

Cultivation is performed under conditions with sufficient light (photosynthesis effective radiation amount of 320μmol m ^-2 s ^-1 or more), humidity 70%, light period 12 hours (temperature 18 ° C), dark period 12 hours (temperature 14 ° C) , Use an air pump to ventilate the hydroponic solution.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, these are not intending limiting this invention.

Example 1
Cultivation method grown by reducing the amount of potassium fertilizer throughout the cultivation period (1) Method 1) Spinach (variety: dimple) was used as a cultivation condition test material. The seeds were washed in 1% NaOCl solution for 30 minutes, then washed with distilled water, placed in a petri dish with moistened filter paper, and then germinated for 6 days in a thermostat at 14 ° C in the dark. . During the germination period, the seed roots grew about 10 mm.

A 10-liter plastic container containing 8 L of hydroponic liquid (39 cm wide, 22 cm deep, 16 cm deep) is floated with a foamed polystyrene board with 10 2 cm square holes, and the sprouting seedlings below the stems are cube-shaped. Wrapped with a sponge, inserted into a hole and transplanted. Cultivation is performed in a growth chamber (MLR-350H, SANYO), humidity 70%, light period 12 hours (temperature 18 ° C), dark period 12 hours (temperature 14 ° C), photosynthesis effective radiation amount 320μmol m ^-2 s ^-1 Set to. The hydroponic solution was well ventilated. Ten plants were planted at the time of fixed planting, and 5 plants with good growth were selected when the hydroponic solution was changed after one week. Hydroponic fluid exchange was performed 4 times a week after the start of cultivation, and harvested on the 34th day after transplanting.

The composition of hydroponics is 3.00 mM KNO ₃ , 2.00 mM Ca (NO ₃ ) ₂ 4H ₂ O, 0.50 mM NH ₄ H ₂ PO ₄ , 1.00 mM MgSO ₄ 7H ₂ O, 26.9 μM EDTA-Fe, 4.55 μM MnCl ₂ 4H ₂ O, 23.1μM H ₃ BO ₃ , 0.38μM ZnSO ₄ 7H ₂ O, 0.16μM CuSO ₄ 5H ₂ O, 0.015μM (NH ₄ ) 6Mo ₇ O ₂₄ 4H ₂ O, pH 6 using 0.1N NaOH The composition of the control group was adjusted to .5 (Table 1). KNO ₃ was reduced to reduce the potassium concentration in the hydroponics, HNO ₃ was added to compensate for the reduced NO ₃ ⁺ , and the pH was adjusted to 6.5 using 0.1N NaOH. Compared with the control plot, the treatment plot (1 / 2K plot), 1/4 treatment plot (1 / 4K plot), and 1/8 treated plot with the potassium concentration in the hydroponics throughout the cultivation period (1 / 8K Ward) was set (Table 2).

2) Measurement item and measurement method On the 34th day after transplantation, the chlorophyll meter value and the number of leaves were measured using a chlorophyll meter (SPAD502, Minolta). After harvesting, the fresh weight was measured, dried in an oven at 80 ° C for 72 hours or more, and then the dry weight was measured to determine the moisture content. After crushing the dry matter, it is decomposed using a microwave sample processor (ETHOS1600, Milestone General Co., Ltd.), and the contents of potassium, magnesium, and calcium are measured using an atomic absorption spectrometer (AA-6800, Shimadzu Corporation), and ICP The contents of copper, iron, manganese, sodium, sulfur, and zinc were measured using an emission spectrometer (IRIS Advantage ICAP, Nippon Jarrell Ash).

(Test results)
Table 3 shows the fresh weight, the number of leaves, the moisture content, and the chlorophyll meter value in each treatment area at the time of harvesting when growing with a reduced amount of potassium fertilizer throughout the cultivation period. The fresh weight and the number of leaves were not significantly different at the time of harvest in each treatment group with reduced potassium fertilizer compared with the control group. The water content was 93.97% in the 1 / 2K group, which was slightly increased compared to the control group, but there was no significant difference in the treated group other than the 1 / 2K group compared to the control group. The chlorophyll meter value was 43.5 in the control plot, while the 1 / 2K plot showed a significantly lower value at 38.3, and the 1 / 8K plot showed a significantly higher value at 48.0.

Fig. 1 shows the effect of the difference in the amount of potassium fertilizer on the potassium content at the time of harvest when growing with a reduced amount of potassium fertilizer throughout the cultivation period. The purpose of this study was to reduce the amount of potassium ingested by the human body after harvesting, so the potassium content per gram of fresh weight was compared. Compared with the control group, there was no significant difference between the 1 / 2K and 1 / 4K groups, but the potassium content decreased significantly in the 1 / 8K group. In the control group, the potassium content was 7.97 mg per gram of fresh weight, and in the 1 / 8K group, it was 5.45 mg, a decrease of 32%.

Table 4 shows the effects of differences in the amount of potassium applied when growing with a reduced amount of potassium applied throughout the cultivation period on the contents of magnesium, calcium, sodium, sulfur, copper, iron, manganese, and zinc at the time of harvest. It was. These elements could be divided into elements with high contents (magnesium, calcium, sodium, sulfur) and elements with low contents (copper, iron, manganese, zinc). In elements with a high content, the content other than sulfur increased with a decrease in the amount of potassium fertilization. In particular, the sodium content showed a marked increase, and each treatment group showed a significantly higher value than the control group. In 1 / 8K section where the amount of potassium fertilizer was the least, the sodium content per gram of fresh weight was 827.7μg, which was 12.7 times that of the control section. Magnesium and calcium contents are also significantly higher in the 1 / 8K, 1 / 4K and 1 / 8K groups than in the control group, respectively, and in the 1 / 8K group, 1.6 and 1.2 times the control group, respectively. Content. In elements with low content, elements other than manganese were significantly reduced in the 1 / 2K zone and copper and zinc in the 1 / 8K zone compared to the control zone.

(Example 2)
Cultivation method without reducing potassium at the beginning of cultivation and reducing the potassium concentration in the hydroponics during the cultivation period (1) Method 1) Cultivation conditions Test materials and cultivation conditions are in accordance with (Example 1). It was.

As in (Example 1), the composition in the hydroponic solution was the control group shown in Table 1, and the treatment group (5W0K group) in which the potassium concentration in the hydroponic solution was 0 from the fifth week after transplanting Four weeks after transplantation, the concentration of potassium in hydroponic fluid was 1/4, and the fifth week after transplantation was set to 0 (4W1 / 4K), and the fourth week after transplantation, the potassium concentration in hydroponic fluid A processing zone (4W0K zone) set to 0 was set (Table 2).

The measurement items were in accordance with those shown in (Example 1).

(Test results)
Table 5 shows the fresh weight, the number of leaves, the moisture content, and the chlorophyll meter value in each treatment area at the time of harvesting when growing with a reduced amount of potassium fertilization during the cultivation period. There were no significant differences in fresh weight, leaf count, and chlorophyll meter values at harvest time in each treatment group with reduced potassium fertilizer compared to the control group. The moisture content was 94.27% in the 5W0K group and increased slightly compared to the control group, but no significant difference was found in the treated group other than the 5W0K group compared to the control group.

FIG. 2 shows the effect of the difference in the amount of potassium applied when the amount of potassium applied is reduced from the middle of the cultivation period on the potassium content at the time of harvest. The potassium content was significantly decreased in each treatment group compared to the control group. At harvest time, the potassium content per gram of fresh weight was 7.97 mg in the control plot, but it was 4.79 mg in the 5W0K plot, a 40% decrease compared to the control plot, and a 3.61 mg, 55% decrease in the 4W1 / 4K plot. In 4W0K, 1.71 mg showed a 79% decrease.

Table 6 shows the effects of differences in the amount of potassium fertilizer when grown with a reduced amount of potassium applied during the cultivation period on the contents of magnesium, calcium, sodium, sulfur, copper, iron, manganese, and zinc at the time of harvest. Showed about. As in the case of growing with a reduced amount of potassium fertilizer throughout the cultivation period, it was possible to divide into elements with relatively high content and elements with low content. In elements with a high content, the content other than sulfur increased with a decrease in the amount of potassium fertilization. Magnesium and sodium contents were significantly higher in each treatment group than in the control group. Magnesium content was 766.8μg / g fresh weight in the 4W0K group with the least amount of potassium fertilizer, 2.3 times the content in the control group. The sodium content was 1646μg / g fresh weight in the 4W0K group, which was 25.3 times that in the control group. The calcium content was also significantly higher in the 4W0K group than in the control group, and the 4W0K group was 1.3 times the content of the control group. For elements with low content, the zinc content decreased significantly in each treatment group compared to the control group, and the content per 1 g of fresh weight was 2.4 μg in the 4W0K group with the least amount of potassium fertilizer. It was 53% of the content of the ward.

(Summary of results)
Spinach is cultivated using hydroponic method, "cultivation method grown by reducing the amount of potassium fertilization throughout the cultivation period (Example 1)" and "cultivation method grown by reducing the amount of potassium fertilization during the cultivation period (implementation) Example 2) ”was set. By reducing the amount of potassium applied, the potassium content decreased (FIGS. 1 and 2) while maintaining growth in both treatment zones (Tables 3 and 5). In Example 1, the potassium concentration in the hydroponic liquid throughout the cultivation period was 1/8 of the control plot (1 / 8K plot), and the potassium content at harvest was reduced to 68% of the control plot. It was. In Example 2, the potassium content at the time of harvest decreased to 21% of the control group in the treatment group (4W0K group) in which the potassium concentration in the hydroponics was 0 after 4 weeks after transplanting. From these results, it became clear that spinach with a low potassium content can be cultivated while maintaining the growth of the edible part by limiting the amount of potassium fertilization during the cultivation period. Moreover, Example 2 was able to reduce the potassium content of the edible part at the time of harvest more efficiently.

Growth was maintained despite the significant decrease in potassium content, and the increase in the contents of some elements was observed at this time, so these increased elements compensated for the decrease in potassium and controlled osmotic pressure. It was thought that he worked. Figure 3 shows the total number of moles contained in 1g of fresh weight of potassium, sodium, magnesium, and calcium, which are elements with a high content, when the amount of potassium fertilizer is reduced and grown during the cultivation period. It was. There was a tendency for the number of moles of sodium and magnesium to increase, and to maintain the total number of moles, especially in the treatment plots where the amount of potassium fertilizer was reduced and the potassium content decreased as a result.

Sodium content increased with decreasing potassium content, but kidney dialysis patients cannot excrete sodium ions sufficiently, so increased sodium ions cause hypertension and edema, which is favorable for dialysis patients with kidney disease is not. Therefore, it is necessary to examine which of the benefits from the decrease in potassium content clarified in this study and the negative effects from the accompanying increase in sodium ions is greater. Dialysis patients with kidney disease have a daily potassium intake limit of 1500-2000 mg. On the other hand, daily salt intake is limited to 5000 to 8000 mg, which is about 2000 to 3200 mg when converted to sodium. Therefore, when comparing the daily potassium intake limit and the sodium intake limit, the sodium intake is 1.3 to 1.6 times higher. Moreover, in this invention, when "it grows by reducing the potassium concentration in a hydroponics from the middle of a cultivation period", potassium content is maximum 7786 micrograms per 1g of fresh weight (control section) to 1706 micrograms (4W0K section) It was reduced by more than 6000 μg (FIG. 2). At this time, the sodium content increased by about 1600 μg from 65 μg (control group) to 1645 μg (4W0K group) per 1 g of fresh weight (Table 6). Therefore, an increase in sodium content of up to about 1600μg per gram of fresh weight can reduce the potassium content by 6000μg or more, and it is considered that potassium restriction can be performed efficiently. Furthermore, since potassium intake is determined only by the food that is ingested, there is only a method of ingesting food with a low content to limit potassium, but food with low sodium content is ingested with restriction of sodium intake There is an effective means of limiting salt (NaCl) rather than the method. Taking these into account, the benefits of reduced potassium content are greater than the negative effects of increased sodium ions, and the findings obtained in the present invention are beneficial for improving the diet of renal dialysis patients. Conceivable.

By producing stably and constantly at a large scale such as a plant factory, it is possible to produce leafy vegetables for dialysis patients with kidney disease and to establish a business with food-related companies.

The effect of potassium fertilization conditions on the potassium content at the time of harvest when growing with a reduced amount of potassium fertilizer throughout the cultivation period. Each value represents an average value ± standard error of potassium content contained in 1 g of fresh weight (n = 5). *** is a t-test and indicates that there is a significant difference at the 0.1% level compared to the control group. The effect of potassium fertilization conditions on the potassium content at the time of harvesting when the amount of potassium fertilization is reduced and grown during the cultivation period. Each value represents an average value ± standard error of potassium content contained in 1 g of fresh weight (n = 5). *** is a t-test and indicates that there is a significant difference at the 0.1% level compared to the control group. Changes in the number of moles of potassium, sodium, magnesium and calcium contained in 1 g of fresh weight in each treated section at the time of harvest when growing with a reduced amount of potassium fertilized during the cultivation period.

Claims (2)

In the method of cultivating spinach by hydroponics, among the five weeks of cultivation, the first three weeks are cultivated by adding KNO ₃ without reducing the potassium content in the hydroponics, and then in the hydroponics Low pH, characterized by adding the same concentration of HNO ₃ in place of KNO ₃ which is the potassium element of the water and adjusting the pH of the hydroponic liquid to 6.0-6.5 with NaOH throughout the cultivation period. A method of cultivating potassium spinach. Low-potassium spinach in which the potassium content at the time of harvest obtained in the hydroponics method of claim 1 is suppressed from 1800 μg to 2300 μg per 1 g of fresh weight.

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