JPH1084766A - Cultivation method for sweet potato - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cultivation method for sweet potatoes capable of increasing the yields of the laminae and necks of the sweet potatoes in order to effectively utilize the laminae and the necks. SOLUTION: This cultivation method for the sweet potatoes consists in repetitively harvesting the laminae and the necks by applying manure before and after fix planting of the seedlings obtd. from nursery beds to rows and cutting the laminae and the necks plural times a year at intervals of 3 to 6 weeks after the fix plating of the sweet potatoes. The cutting of the laminae and the necks is preferably executed when the vitamin K content in the laminae attains >=800μg/100g. As a basal dressing quantity, 5 to 15kg, per 10a, nitrogen fertilizer, 15 to 30kg phosphoric acid fertilizer and 10 to 20kg potassium fertilizer are applied. Further, the nitrogen fertilizer is preferably additionally applied at 20 to 100kg per 10a during the time after the previous cutting to the next cutting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cultivating sweet potatoes in which the leaf blades and stems rich in nutritionally effective vitamins and minerals are repeatedly cut.

[0002]

2. Description of the Related Art Sweet potatoes, also known as sweet potatoes or kara potatoes, are counted as one of the main food crops in Japan. By production area, Kagoshima and Miyazaki prefectures account for about 50 of the cultivated area nationwide.
%, And its use is mostly used for starch processing. However, import of cheap starch has increased in recent years, and domestic starch production has decreased. Along with this, the cultivated area of sweet potatoes has been decreasing year by year, and creation of new added value of sweet potatoes is required. The method of cultivating sweet potatoes is such that healthy seed potatoes are laid down on an electric heating greenhouse (nurse bed) heated to about 25 ° C. in early March, and seedlings are collected from late April to late May. Thereafter, the seedlings obtained from the seedbed were obliquely inserted into ridges of 60 to 70 cm in width and 30 to 40 cm between plants where compost and chemical compound fertilizer were applied as a base fertilizer. Planted by the method. At this time, it is a usual method to coat the ridge with black vinyl, but sometimes no coating is applied. After planting, it is cultivated in the open field without fertilizer during the cultivation period from early June to late October. In early November, the leaves and stems are cut off and the potatoes are harvested.

[0003]

However, even though the leaf blade and stem of the sweet potato are rich in vitamins and minerals, fresh or sun-dried sweet potatoes are used as feed. There are no known effective uses other than feeding to livestock or plowing into fields to produce fertilizer. The leaf blades and stems harvested around November are yellowing and decay due to a decrease in temperature, and a decrease in vitamin content is inevitable. Furthermore, at present, the leaf blade portion containing a large amount of nutrients accounts for less than 20% of the whole cut. Accordingly, the present invention has been made in view of the above-mentioned current state of the prior art, and aims to effectively utilize the leaf blade and the stem of the sweet potato, and to increase the yield of the leaf blade to increase the amount of vitamins and minerals. It is an object of the present invention to provide a novel method for cultivating sweet potatoes capable of obtaining a larger amount.

[0004]

Means for Solving the Problems The present inventors have been exploring nutritionally effective resources for various by-products generated in agricultural production activities and agricultural processing processes.
We have been conducting intensive research with the aim of recovering vitamins and minerals that are safe from natural products. In the process,
Focusing on the fact that the leaf blades of sweet potatoes are rich in nutritionally valuable vitamins and minerals, and have been working to increase the amount obtained, the leaf blades and stems of sweet potatoes have been 1
It has been found that the above-mentioned object is achieved by mowing several times a year, and the present invention has been completed. That is, the present invention is different from the conventional sweet potato cultivation method in which the leaf blade portion and the stem portion are cut only once a year, and fertilizer is applied before and sometimes after the planting of the seedling, and 3 to 6 weeks after the planting. The present invention relates to a method for cultivating sweet potatoes in which leaf blades and stems are repeatedly cut a plurality of times a year, specifically 3 to 7 times at intervals.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the method for cultivating sweet potatoes of the present invention will be described in detail. First, according to the conventional method of growing sweet potatoes,
A healthy seed potato is laid down on a nursery bed heated to about 25 ° C,
Seedlings are taken from late April to late May. The seed varieties are not particularly limited, but include, for example, Kokei 14, Koganesengan, Simon 1, Benihayat,
In addition to Norin 1 and Norin 2, Venezuma, Benikomachi,
Tursengan, red and red, southern taka, shiroyutaka, yamakawa purple and the like. During the seedling raising, at least one of a compost and a chemical fertilizer is applied as a base fertilizer. A typical base fertilizer amount is 5-15 kg of nitrogen fertilizer per 10a (that is, 5 kg).
~ 15kg / 10a), phosphate fertilizer 15 ~ 30kg /
10a and potassium fertilizer should just be in the range of 10-20 kg / 10a. After the basal fertilizer is applied, the ridge having a width of 60 to 70 cm is coated with black vinyl used in mulch cultivation. Cuts are made in the coated ridge at intervals of 30 to 40 cm between the plants, and the seedlings are planted. At that time, even if the planting is carried out on the ridge which is not coated with black vinyl, the cultivation method of the present invention is not hindered at all. As the planting method, any conventional method such as vertical insertion may be adopted. In addition, there is no problem in a method in which healthy seed potatoes are directly planted in ridges without taking seedlings. Next, after cultivation for a predetermined period in the field, mow from the place about 10 cm above the ridge,
Harvest leaf and stem of sweet potato. The resulting leaf blade and stem contain abundant nutritionally effective vitamins and minerals, especially the leaf blade contains several to 20 times more vitamins than the stem Have been.

The nutritionally effective vitamins include, for example, fat-soluble vitamins such as vitamins A, D, E, and K; water-soluble vitamins such as vitamins B and C; and minerals such as sodium, magnesium, and phosphorus. , Potassium, calcium, iron, copper, zinc, and other elements. The present inventors could obtain the finding that it is most nutritionally desirable to determine the cutting time of the leaf blade and the stem based on the vitamin K content of the leaf blade. That is,
From a botany perspective, it is important to know the nitrogen nutritional status of sweet potatoes. It is generally known that when the nitrogen content of a plant increases, the green color of the leaves increases and the amount of chlorophyll increases. In the present invention, when the amount of chlorophyll in a sweet potato increases, the amount of nutritionally effective vitamins also increases. In particular, there is a high correlation with vitamin K which is a fat-soluble vitamin. The amount can be determined. According to the correlation between the amount of chlorophyll and the amount of vitamin K, the cutting time of the leaf and stem of the sweet potato is as follows.
It has been found that the interval of 3 to 6 weeks at which the vitamin K content in the leaf blade becomes 800 μg / 100 g or more is optimal. In the open-field cultivation, the growth state of the sweet potato generally depends on the weather conditions of each cultivation year, and the optimal cutting time during 3 to 6 weeks changes. Determining the cutting time based on the vitamin K content of the leaf blade of 800 μg / 100 g or more can be said to be an effective means without being affected by the weather conditions in each cultivation year. Therefore, the reaping interval in the present invention does not necessarily mean that reaping is performed at regular intervals, for example, every three weeks, with an accurate interval. The harvest interval of 3 to 6 weeks means from the first day of the third week (15 days) to the last day of the sixth week (48 days).

[0007] The content of vitamin K is usually analyzed using high performance liquid chromatography (HPLC). However, since the analysis operation is complicated and requires skill, there is a tendency that measurement in a field lacks simplicity. Of course, by using appropriate equipment or facilities, not only the HPLC method, but also a spectrophotometric method of measuring and quantifying the absorbance of vitamin K at the absorption maximum wavelength, a colorimetric method of reacting with sodium alcoholate and performing colorimetry, The vitamin K content in the leaf blade can be measured by an oxidation-reduction method, a polarography method, a gas chromatography method, or the like, which can be used for quantification of a high-purity product such as a raw material for a medical product. In order to easily determine the optimal cutting time in a field, it is preferable to measure the content of vitamin K using a chlorophyll meter conventionally developed for paddy rice. Here, the chlorophyll meter is a lightweight and compact measuring instrument that easily displays digitally the amount of chlorophyll contained in rice leaves without damaging the leaves. This instrument is
It utilizes the principle that when the green color of the leaves becomes darker, the nitrogen content of the plant increases and the amount of chlorophyll increases. More specifically, there is a maximum absorption of chlorophyll6
This is a measuring instrument for obtaining the chlorophyll amount based on a difference in optical density between two wavelengths of a wavelength range of 00 to 700 nm and an infrared range having no absorption.

[0008] In the cultivation method of the present invention, if the leaf and stem of the sweet potato are further cut off, the nutrients in the soil, particularly nitrogen, decrease, so that the amino acids and photosynthesis of the protein components constituting the protoplasm of plant cells are reduced. It is desirable to supplement the nitrogen contained in the running chlorophyll. Therefore, after mowing at intervals of 3 to 6 weeks, it is preferable to mainly add nitrogen fertilizer to grow leaf blades. The time and frequency of topdressing are not particularly limited, but are preferably within one week from the cutting of the leaf blade and the stem, and the fertilizer to be applied is preferably near the planted seedling. The fertilizer application rate of the nitrogen fertilizer is generally in the range of 20 to 100 kg / 10a, more preferably in the range of 30 to 90 kg / 10a. 2
If the topdressing is less than 0 kg / 10a, the sweet potato cannot sufficiently absorb the nitrogen fertilizer applied to the soil, and if it is cut repeatedly, the leaf blade and the stem cannot grow, and may turn yellow and die. On the other hand, if the topdressing is performed more than 100 kg / 10a, the base concentration in the soil will be increased, and the root will be damaged, and root rot may occur.

Nitrogen fertilizers used for base fertilizer and top dressing include ammonium sulfate, salt ammonium, ammonium nitrate, urea, lime nitrogen and the like. Examples of the composite chemical fertilizer include phosphorus phosphorus, phosphorus phosphorus sulfide, and the like. This phosphorous ammonium sulfide is prepared by adding ammonium sulfate (ammonium sulfate) and potassium sulfate and potassium chloride as a potassium source to a mixture of ammonium phosphate monobasic and diammonium phosphate, and adding nitrogen: phosphoric acid: potassium to 10:16: It is an advanced chemical fertilizer granulated to a ratio of 16. As the compost, for example, cow manure is separated into solid and liquid by a gravity flow method, a centrifugal separator, a rotary screen, etc., and woody raw materials such as bark and sawdust are mixed to promote moisture control, deodorization, and air permeability. Thereafter, a mature ripe compost is preferably used in which composting is progressed while allowing the fermentation to mature for several weeks and performing sufficient turning over during that time. This fully matured compost contains nitrogen, phosphoric acid, potash, lime, formic acid (MgO) and the like and trace elements, and has the effect of enriching these nutrients in the soil to enhance the soil strength.

According to the sweet potato cultivation method of the present invention in which the leaf blade and the stem are cut a plurality of times in one year, the leaf blade is 3 to 11 times as large as the conventional method and the stem is up to 2 times. .5
The yield is significantly increased. In addition, the leaf blade can be efficiently harvested, that is, 40 to 60% of the entire cut. As described above, the leaf and stem of the sweet potato are rich in vitamins and minerals. For example,
Compared to spinach per unit weight in the leaf blade, vitamin C is about twice as much and vitamin E is 7-11
Twice as much as β-carotene (provitamin A). The usage of the leaf blade and stem of the sweet potato obtained by the cultivation method of the present invention is as follows. For example, the blade and stem are first steamed, shredded, then pasted, dried, and then subjected to processing such as powdering. The obtained powder can increase the vitamin / mineral content of the food, and also has a high fiber content, as an additive for various foods such as processed flour such as bread, noodles and confections, and fishery paste products. Therefore, it is possible to replenish vitamins and minerals, which are apt to be lacking in the eating habits of the now lopsided people. In addition, sweet potato potatoes can be used for food as before,
It can be used for starch processing.

[0011]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 The cultivation test was carried out in three groups in which 10 sections each having a length of 4 m and a width of 4 m were set to form one group, and the arrangement of each section was changed. Each section (total 3
0 section) is ridge width 60c coated with black vinyl
m, consisting of ridges of 40 cm between plants. In addition, 1
Approximately 10kg of nitrogen fertilizer and 20k of phosphate fertilizer per 0a
g, 15 kg of potash fertilizer, 100 kg of the fully-ripened compost and 10 kg of phosphorous sulfide were applied to the entire cultivation area. The composition of the fully matured compost was 2.1% of total nitrogen, 4.5% of phosphoric acid, 2.8% of potassium, and 30.0% of water, and its pH was 7.1.

[0012] Sixty seedlings of sweet potatoes (variety: Simon No. 1) obtained from the heated nursery were planted obliquely in each section and planted.
It was cultivated for 20 weeks from the beginning of the month to the end of October. Test plot a has a total of 7 times at 3 week intervals after planting, test plot b has 5 times at 4 week intervals, test plot c has 4 times at 5 week intervals, and test plot d has a total of 4 times at 6 week intervals. At this time, the leaf blade and stem were cut off. The control section a was cut only once 20 weeks after planting in the same manner as the normal cultivation method.
In contrast, the control group b was 10 times at 2-week intervals, and the control group c was 7 times.
The control section d was cut three times in total at eight-week intervals, the control section e was cut three times in total at nine-week intervals, and the control section f was cut twice in ten-week intervals. Here, in order to match the cumulative cultivation period for each test plot and each control plot, test plots a, d, control c, control d, and control e were finished at the same time as control plot a. And the cultivation was completed. For example, in test plot a, 3
They were reaped six times at weekly intervals and thereafter at two-weekly intervals.

For the leaf blade and stem of the sweet potato cut at each time, the total cut amount, the cut amount of the leaf blade, and the cut amount of the stem were measured, and the vitamin K content was also analyzed. . In the same test and control plots except the control plot a, the weights of the leaf blades and stems obtained for each cutting were totaled. Table 1 shows the average amount of cutting and the ratio of leaf blades and stems of the three groups. Table 1 below
As shown in the above, in the test plots a to d, the overall average reaping amount was 86 kg, and the average ratio of the leaf blade was 48.5%, which was good. On the other hand, in the cultivation results of the normal cultivation method, that is, the cultivation result of the control section a, the total cutting amount was 50 kg, the ratio of the leaf blade portion was 22%, and the ratio of the leaf blade portion to the entire cutting was extremely low.

[0014]

[Table 1]

The content of vitamin K was analyzed by the HPLC method, and as a pretreatment, the leaf blade and stem obtained in Example 1 were treated as follows. First, ethanol-water (8: 2) is added to the weighed leaf blade or stem, and 5
Shake for minutes. Next, n-hexane was added, and after shaking and centrifugation, a crude extract was obtained. This crude extract was passed through a column packed with silica gel and purified. As the HPLC method, a method is known in which a chemical reduction method using sodium borohydride, an electrical reduction method, a method of reducing vitamin K to fluorescent hydroquinone K by a platinum black column reduction method, and then a fluorescence detection method. I have. Of these, the results of analyzing the vitamin K content according to the chemical reduction method are shown in Table 2 below. The increase rate of the leaf blade and the leaf stem (leaf blade and stem) in Table 2 is obtained by integrating the increase rate of the cut amount of the leaf blade and the leaf stem and the vitamin K content with respect to the control a. It was done. In addition, each vitamin K in the leaf and stem of Table 2
FIG. 1 is a plot of the content. In the test plots a to d, after the green color of the leaf blade became dark, a simple analysis of the amount of chlorophyll was performed every day using the chlorophyll meter. Each value was 46 or more.

[0016]

[Table 2]

[0017] At least 2.9 of the stem is added to the leaf blade of the sweet potato.
It contains twice the amount of vitamin K (control group e), and is in the order of 4 times in each test group. In addition, as compared with the control group a, the vitamin K content in the leaf blade was 1.5 times or more in each of the test groups, and nutritionally effective vitamin K was contained in the whole blade blade and leaf stem. 5.2-7.3 times and 3.3-4.4 times were obtained, respectively. Example 1 above
To summarize, cutting the leaf and stem of sweet potatoes at intervals of 3 to 6 weeks shows the percentage of leaf and its vitamin K
It was possible to efficiently harvest leaf blades and stems whose content was increased and thus the amount of vitamin K obtained was increased.
In the control plot c, although the overall cut amount and the ratio of the leaf blade were not so inferior to those of the test plot, the amount of vitamin K obtained in the leaf blade and the whole was small.

Example 2 As a base fertilizer, a ratio of approximately 10 kg of nitrogen fertilizer, 20 kg of phosphate fertilizer and 15 kg of potassium fertilizer per 10 a was determined.
A cultivation test was carried out in the same manner as in Example 1 by applying the same ripe compost and phosphorus ammonium sulfide to the three compartments as in Example 1. However, the test plot e cuts 6 times at intervals of 3 weeks after planting,
In each case, 0.48 kg of a chemical nitrogen fertilizer (ammonium sulfate) was given to a test plot of 30 kg / 10a, that is, 4 m × 4 m. The test plot f cuts at intervals of three weeks after planting, and in each case, 0.97 kg (60 kg / 10a) of ammonium sulfate was applied to the test plot.
Gave. The test plot g was harvested at intervals of three weeks after planting,
In each case, 1.45 kg (90 kg) of ammonium sulfate was added to the test plot.
/ 10a) given. Cut amount of leaf stem portion of sweet potato cut as described above (total amount), cut amount of leaf blade portion, cut amount of stem portion, and vitamin K content of leaf blade portion (unit: μg / 100g) Are shown in Table 3. Table 3 shows that Example 1 was harvested at intervals of three weeks after planting without additional fertilization.
And the cultivation results of the control plot a according to the normal cultivation method.

[0019]

[Table 3] After cutting the leaf and stem of sweet potatoes at intervals of 3 weeks, according to the test plots e to g in which nitrogen fertilizer is applied each time, the ratio of leaf blades is further improved, and the total cutting amount is about twice as much. Improved above. At the same time, in the test plot f, the vitamin K content and the amount obtained in the leaf blade part were also improved by 1.4 times and 5.0 times, respectively, as compared with the test plot a.

Next, with respect to the leaf blade and stem of the sweet potato obtained in the control plot a and the test plot f, the component ratio in 100 g thereof and the rate of increase (%) of each component in the test plot f with respect to the control plot a. Are shown in Table 4.

[Table 4] As is evident from Table 4, the content of vitamins and minerals in the leaf blade is significantly increased except for sodium.

In the test plots a to g and the control plot a of Examples 1 and 2, the leaf blades of each plot were collected at random.
The chlorophyll and vitamin K contents in the three samples were measured. The measurement results are shown in the graph of FIG. As shown in “chlorophyll content−vitamin K content” in FIG. 2, the regression equation is represented by y = 5.0193x−147.27, and the correlation coefficient r
Was found to be highly related to 0.9578. The above-mentioned chlorophyll meter can be used as an instrument for easily measuring chlorophyll analysis in the leaf blade in a field. This chlorophyll meter (SPAD-502: Minolta Camera Sales Co., Ltd.)
FIG. 3 shows the vitamin K content and chlorophyll meter (SPAD) value of the same sample as described above. As shown in "Vitamin K content-Chloroplastometer (SPAD) value" in FIG. 3, the regression equation is represented by y = 0.135x + 35.074, and the correlation coefficient r is highly related to 0.9050. In the present invention, the leaf blade and stem are cut off when the vitamin K content of the leaf blade, which cannot be obtained at intervals other than 3 to 6 weeks, becomes 800 μg / 100 g or more, that is, from FIG. It is preferable that the measured value indicates 46 or more.

[0022]

According to the present invention, after planting sweet potato seedlings,
By repeatedly cutting the leaf blades and stems at intervals of 6 weeks, the leaf blades and stems rich in nutritionally effective vitamins and minerals can be efficiently harvested. In particular, by cutting when the vitamin K content in the leaf blades exceeds a predetermined value, or by applying fertilizer after cutting, the content of other vitamins and minerals other than vitamin K increases. The leaf portion of the sweet potato can be efficiently harvested.

[Brief description of the drawings]

FIG. 1 is a graph showing the content of each vitamin K in the leaf blade and stem of a sweet potato harvested in each cultivation plot.

FIG. 2 is a graph showing the relationship between the chlorophyll content and the vitamin K content in the leaf blade of a sweet potato.

FIG. 3 is a graph showing the relationship between the vitamin K content in the leaf blade of sweet potato and the chlorophyll meter (SPAD) value.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Osamu 1-25-1, Hanazono, Kumamoto City, Kumamoto Prefecture Kumamoto Flour Milling Co., Ltd.

Claims (3)

[Claims] 1. Fertilizer is applied at least once a year at an appropriate time, and a potato seedling is planted.
By harvesting several times a year at intervals of ~ 6 weeks,
A method for cultivating sweet potato, characterized by repeatedly harvesting the leaf blade and stem. 2. The vitamin K content in the leaf blade is 800 μm.
The method for cultivating sweet potato according to claim 1, wherein the leaf blade portion and the stem portion are cut off at the time of the increase to g / 100g or more. 3. After harvesting of the leaf blade and stem, from 20 to 100 per 10a between the cutting and the next cutting.
The method for cultivating sweet potato according to claim 1 or 2, wherein kg of nitrogen fertilizer is applied.