JPH03180125A - Hydroponic film - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to a film used for hydroponic cultivation [Prior Art] Hydroponic cultivation has a problem of continuous cropping in greenhouse horticulture (house cultivation). It has long been attracting attention as an alternative to greenhouse cultivation in order to avoid this problem or to save labor. However, the current hydroponic cultivation area is approximately 0.0% of the total greenhouse cultivation area.
It accounts for only 7% of the population, and despite its many recognized characteristics such as clean production and fast growth rate, it can be said that its spread is slow.

One of the reasons for this is that facility costs are higher compared to conventional soil cultivation. For this reason, recently a simple cultivation method called NFT (Nutrient FlowT) has been introduced.
echnique) cultivation and rock wool cultivation have been introduced, and this has contributed to expanding the cultivation area.

The NFT cultivation referred to here is a method of cultivating crops using a flowing nutrient solution.The roots of the crops are simply wrapped in a film in the form of a tunnel, and the nutrient solution flows through this tunnel-shaped film (bottom). It flows down naturally following the slope. Crops grow and are cultivated by absorbing the nutrient water in the nutrient solution with their roots. The flowing nutrient solution returns to the supply tank and is used for circulation.

On the other hand, rock wool cultivation is also a method of cultivating crops using a flowing nutrient solution, but the rock wool used in this cultivation is not used to simply support crops like conventional charcoal or urethane foam, but rather to grow crops in a nutrient solution. It is intended to be impregnated with and retained for a certain period of time. The rock wool that characterizes this cultivation comes in two types: one for growing bacteria and one for planting.The one for raising seedlings is 7.5x7.
5X5. Approximately 0cm, 30 x 7, 5 x for planting
It is cut to a size of about 91 cm and used. All of them are used either wrapped in a film tunnel or placed on top of the film. There are 1 ways to supply the nutrient solution.
There is an irrigation type in which the remaining liquid supplied to the crops is discharged to the ground on the path side through a drainage hole, and a circulation type in which it is returned to the nutrient solution tank and used as a supply liquid again.

Many other hydroponic cultivation methods have been put into practical use, but all of them mainly involve placing a film on the inside of the cultivation tank (bottom, wall) or using a medium (with various materials) to prevent leakage of the nutrient solution. (containing a nutrient solution) is wrapped in a film, and the roots are often in contact with or wrapped in the film.

(Problem to be solved by the invention) However, in hydroponic cultivation such as NFT cultivation and rock wool cultivation, the root morphology and environment are unique to hydroponic cultivation, in other words, the nutrient solution is in direct contact with the roots of the crop. At the same time,
Since the nutrient solution is shared by the crops in one cultivation container, if there are spores of pathogenic bacteria nearby, these spores can easily infect the roots in the form of dirt, etc., causing disease in this area. There was a problem in that it was easy for this to occur. Another problem is that when pathogenic bacteria enters the nutrient solution, they are sent directly to the roots along with the nutrient solution and immediately cause infection, resulting in very rapid disease transmission.

For this reason, even though these hydroponic cultivation methods have advantages such as relatively low facility costs, they have not become widespread.

This invention was made in order to solve these conventional problems, and provides a hydroponic film that can effectively prevent the occurrence and transmission of crop diseases. purpose.

[Means to solve the problem]

The hydroponic film provided by the present invention is literally a thermoplastic resin film used for hydroponic cultivation, and the resin is an inorganic porous carrier holding a metal with a bactericidal effect.
．． It contains 1 to 20% by weight.

Examples of the thermoplastic resin include branched low-density polyethylene (LDPE), linear low-density polyethylene (L-LDP), and linear low-density polyethylene (L-LDP).
E), high density polyethylene (HDPE), polyethylene of ethylene-vinyl acetate copolymer (EVA), polyolefin resins such as polypropylene, polyamide resins, polyester resins, polyacrylic resins, polyvinyl chloride resins, etc. can. These resins are
Can be used alone or in combination. LDPE, L-LDPE, and EVA are good in terms of cost and performance.

The practical thickness of the film is 10 to 200μ, but from the viewpoint of cost and performance, 20 to 100μ is preferable.

Metals that have bactericidal effects include silver, copper, and zinc.

Examples include nickel and tin, but silver and copper are particularly excellent in terms of performance such as bactericidal effect.

Inorganic porous carriers include 1 synthetic aluminum silicate, perlite, shirasu balloons, various synthetic and natural zeolites, weathered reef-building coral grains, sepiolite, vermiculite, pumice, activated clay, kaolin, talc, and various synthetic and natural zeolites. hydrotalcite, snowtex, bentonite,
Fine powders such as diatomaceous earth and activated carbon with an average particle size of 30 μm or less, preferably 10 μm or less can be used. Among these, various zeolites and weathered reef-building coral grains are preferable in terms of their performance and cost.

The amount of the metal retained in the inorganic porous carrier varies depending on the carrier and the type of metal, but it may generally be in the range of 0.001 to 25% by weight. For example, when holding silver with zeolite, 0.1 to 15 ffilt%, preferably 0.1
~5% by weight.

Two methods can be used to retain the metals in the inorganic porous carrier: an ionic bonding method and a coating method.

The ion bonding method is a method of retaining metal ions from an aqueous solution of a metal salt on the surface of a carrier using an ion exchange reaction.

This is effective for so-called inorganic exchangers (such as zeolites) in which the carrier exhibits the phenomenon of ion exchange. The coating method is a method in which a carrier is immersed in an aqueous solution in which a metal salt is dissolved, the aqueous solution is neutralized, and the surface of the carrier is coated with metal. This is effective for porous supports that do not exhibit the phenomenon of ion exchange.

The lower limit of the fungicide content (amount added to thermoplastic resin) is O.
, 1fil1% is set because if it is less than this, the sustainability of the bactericidal effect will be reduced.The reason why the upper limit was set at 20fii% is that if it exceeds this, not only the strength of the film will decrease, but also the strength during film forming will be reduced. This is because problems such as foaming will increase. The preferred content is 0.1 to 5 rfLM%.

Originally, the roots of crops grow smoothly and perform their functions in a light-free environment in the soil.

Therefore, the film used here should not be exposed to sunlight from the viewpoint of controlling the physiology of the roots, controlling plate temperature, and preventing the growth of green algae, moss, and harmful microorganisms, and should be black, white, silver, etc. It is preferable to color it with a color and block it from light. The light transmittance is 10% or less, preferably 0 to 5%. 10
If it exceeds %, the above purpose cannot be achieved. Single layer,
Or two layers such as white/black, silver/black, or transparent/SFi/
Three layers, such as transparent ones, are also possible. In order to prevent high temperatures in summer, it is necessary to reflect incident sunlight, and in that case, it is preferable to use a reflective layer of silver, white, etc. on the surface (outer surface).

For the second and third layers, the same resin may be used, or different resins may be bonded together. In the case of lamination, at least the inner layer in contact with the nutrient solution contains a fungicide.

As for the method of coloring, it is preferable from the viewpoint of cost and performance to use one sample of a mixed acid as a coloring agent. It can also be printed. In addition, the silver color can be aluminum vapor-deposited or bonded with aluminum foil.

Furthermore, in order to lower the temperature of the roots due to the heat of vaporization, the film may be provided with minute holes with a diameter of several curves or less. However, since the nutrient solution will flow through the bottom of the film, no small holes will be provided.

The film is made of HDPE, PP, PET, PVA for reinforcement.
It may also be bonded to a textile product such as a so-called non-woven fabric made of long fibers or split fibers made of thermoplastic resin.

[Effect]

the above! When hydroponic film is used as a container for nutrient solution, its bactericidal effect effectively prevents the occurrence and transmission of diseases on crops, especially the roots. There are various theories as to how this is achieved. However, it is generally considered as follows.

In other words, silver, copper, zinc, etc. in the film generate active oxygen, which has a bactericidal effect similar to that of ozone and hydrogen peroxide, and this active oxygen kills filamentous fungi that cause crop diseases. ) and bacteria, and are thought to kill them.

[Examples 1 to 3] (I) Add a bactericide and a silver coloring agent to a thermoplastic resin in the following manner, knead and granulate it, and then mold it into a silver unit with a thickness of 30 μm and a width of 1 l 1001 I1. Layer film (
(light transmittance: 0.5%), that is, films of Examples 1 to 3 were created.

(1) Thermoplastic resin: LLDPE (Yukalon LL, UA420 manufactured by Mitsubishi Yuka) (2) Disinfectant: Average particle size 5 μ, S 102 / A 1
An 8-type zeolide with a molar ratio of 203 to 1O was subjected to an ion exchange reaction in a 0.3 molar silver nitrate aqueous solution to convert it into Ag-zeolite, which was then filtered and washed with water to remove excess silver ions. Zeolite with a silver content of 4% by weight was obtained by drying at 100-110°C.

(3> Amount of disinfectant added: Film of Comparative Example 1: No additive Film of Example 1: 15 wt% added Film of Example 2: 5 ffl amount % added Film of Example 3 = 0.2 wt% added nium (Using a masterbatch (PEX 3262 silver) containing 30% by weight of powder) (6) Forming the film by a general inflation molding method (extruder 65 mmφ, die 350 fullφ) (rl) Silver single-layer film of Examples 1 to 3 Tomatoes were cultivated in Rockwool using the method described below, and the occurrence of bacterial wilt disease, which occurs during high-temperature seasons, was investigated.

(1) Cultivation was carried out by arranging rock wool planting mats wrapped in each film in a greenhouse with a width of 6.0 m and a length of 30 m. This planting mat is 30cm wide and 7.5cm high.
Ten blocks with a length of 91 cm and a length of 91 cm were lined up to form a cultivation bed with a length of about 9 m.

This was completely covered and packaged with the silver film, that is, the film of Comparative Example 1 and the films of Examples 1 to 3, and four cultivation areas were established.

(2) Separate liquid supply tanks were installed in each area to enable circulation cultivation.

(3) The nutrient solution was formulated using the so-called Yamazaki and tomato formulation.

The blending amount (standard concentration) per water toooi is as shown in the table below.

(4) 4! The liquid was supplied by dripping to each plant using a microtube method. Control of supply amount and liquid concentration (
(confirmed by EC value) was performed according to the growth condition and growth stage of the tomato.

(5) As the tomato variety, the Takii variety "Momotabe" was used.

(6) Seedlings were sown in rock wool seedling blocks on February 24, 1999, and then the prescribed cultivation management was carried out using the above-mentioned Yamazaki prescription solution. Seedlings were then collected at the point where the roots reached the bottom of the seedling raising block and there were 7 to 8 leaves on the tree. I planted this seedling on April 1st.
On the 5th day, the plants were transplanted to the above-mentioned planting mat with a spacing of 40 cm (22 plants in each group), and a cultivation test was started. The first inflorescence bloomed and set fruit around May 7th, and growth progressed thereafter, and harvesting began around June 20th.

Table 1 shows the results of the above investigation. The survey results were expressed as the rate of diseased strains (%) for each survey date.

The characteristic of bacterial wilt disease is that during the harvest period, the entire plant suddenly wilts, turning into a blight-like appearance, and when the stem at the ground level is cut, a white sap oozes from the ducts. Whether or not the strain is a disease-causing strain is determined by the presence or absence of such phenomena.As is clear from Table 1, in the film of the comparative example, symptoms suddenly appeared in early July when the air and liquid temperatures rose. It spread to about 2/3 of the plants. On the other hand, in the films of Examples 1 to 3, the occurrence of disease and its transmission were very slight, and it can be said that the transmission to other strains was largely prevented.

(Examples 4 to 6) (I) A black mixed raw material made by adding a bactericide and a black coloring agent to a thermoplastic resin as described below, and a white mixed raw material made by adding a bactericide and a white coloring agent to the same thermoplastic resin. are kneaded and granulated, and then molded to obtain a white layer with a thickness of 1
5μ, black layer thickness 15μ, total thickness 30μ, width 11μ
00mm black and white two-layer film (light transmittance 0.5%),
That is, films of Examples 4 to 6 were created.

(1) Thermoplastic resin: LLDPE (Yukalon LL, UA420 manufactured by Mitsubishi Yuka) (2) Bactericide: Coral Sand (Jij) with an average particle size of 5μ
After desalinating the L-shaped reef-building corals by washing with water, they were dried under reduced pressure for 200 min
It is activated by heating and drying at ~400°C for 2 hours to decompose the attached organic components and activate the pores of the coral sand. This activated coral sand is sufficiently immersed in a silver ammonia complex salt aqueous solution prepared by adding aqueous ammonia to a silver nitrate aqueous solution, neutralized by adding glucose to the aqueous solution, and coated with silver by standing for 10 hours. After coating is completed, it is evaporated to dryness under reduced pressure at 200 to 300°C. Coral sand with a silver content of 4% by weight was thus obtained.

(3) Amount of fungicide added: Film of Comparative Example 2: No additives Film of Example 4: 15 wt% added Film of Example 5: 5 wt% added Film of Example 6: 0.2 wt% added The fungicide was added equally to both the white and black layers.

Addition of 3% by weight of rack (using a masterbatch containing 30% by weight of carbon black manufactured by Tokyo Ink (PEX3286 Black 3S)) Addition of 10% by weight of titanium oxide (masterbatch containing 40% by weight of titanium white manufactured by Tokyo Ink (PEX 3009J White)) (7) Forming of film: Using the so-called Dailamin inflator molding method, in which white and black raw materials are melted and fed from separate extruders to one die. (Extruder 50IIImφ x 2, die 35011Ilφ two-layer die) (H) Rock wool cultivation of tomatoes was performed using the black and white two-layer films of Examples 4 to 6, and the problem occurred during the low temperature period (December to March). We investigated the occurrence of root rot wilt.

The cultivation period is different, and therefore the cultivation management is different accordingly, and the films covered and packaged with rock wool are four types of black and white two-layer films (film of Comparative Example 2, films of Examples 4 to 6). Other than this, the same procedure as in case (II) of [Examples 1 to 3] was carried out. That is, the seeds were sown on August 10, 1988, transplanted on September 25, and harvest started on December 21. In addition, (If
Even in the warm season, the temperature above ground is 23-28℃ during the day and 8-1℃ at night.
The appropriate temperature was to maintain it at 0°C, and the heat retention and heating for this purpose were carried out as appropriate using normal methods.

Table 2 shows the results of the above examination, and the results of the 31 examinations are expressed as the rate of diseased strains (%) for each examination date.

Incidentally, root rot wilt is characterized by the young leaves at the tip first wilting, and then the entire plant begins to yellow, starting with the lower leaves, and gradually withers. When cutting a stem 15 to 20C1 above the ground, the ducts have turned brown. Whether or not the strain was a pathogenic strain was determined based on the presence or absence of such a phenomenon.

As is clear from Table 2, in the film of Comparative Example 2, diseases occur after December when the temperature drops.
More than 72 strains were infected. In the films of Examples 4 to 6, there were few diseases and almost no infection with other strains was observed.

(m) Using the same black and white two-layer film as in Examples 4 to 6, strawberries were cultivated using NFT as described below, and the occurrence of root rot was investigated.

(1) (H) of [Examples 1 to 3] and [Examples 4 to 6]
Four sets of raised beds with a bed width of 50cI11 and a length of 9m were installed in the same house as (■).The beds had a slope of !/80 in the length direction, so that the nutrient solution naturally flowed down. Each bed is equipped with a liquid supply tank and the nutrient solution is circulated. Each bed is lined with a film to form a flow path for the nutrient solution and to prevent liquid leakage. , which also covers the roots of crops.

(2) The nutrient solution was prescribed using the so-called strawberry Kawasaki prescription.

Blend 11 (standard concentration) per 10,001 liters of raw water is as shown in the table below.

(3) The amount and concentration of the nutrient solution to be supplied was adjusted based on the strawberry cultivation situation.

(4) The strawberry variety used was “Jomon Wase.”

(5) Seedlings were harvested in mid-August 1986 and NF was grown in a separate greenhouse.
Seedlings were raised using a T-bed. During seedling raising, the culture medium was changed to water only, and flower bud differentiation was performed by so-called nitrogen interruption treatment. In addition, the ceiling of the house was covered with cheesecloth (shading rate: 50%) to keep the water temperature below 30°C during seedling raising. September 1
On the 6th, the bacteria were transplanted into NFT cultivation beds. The spacing between the plants is 30c.
m (30 plants in each ward). Flowering and fruiting began around November 1st, and harvesting began around December 2nd.

Table 3 shows the results of the above investigation. The survey results were expressed as the rate of diseased strains (%) for each survey date.

Symptoms of root rot include the entire plant exhibiting symptoms of green wilt, dying in a short period of time, and reddish-brown discoloration of the central pillar of the roots. Whether or not the strain was a pathogenic strain was determined based on the presence or absence of such a phenomenon.

As is clear from Table 3, in the film of Comparative Example 2, diseases occur after December when the temperature drops.
Infected with 3 or more strains. In the films of Examples 4 to 6,
There was little incidence of disease, and almost no infection with other strains was observed.

In addition, in the films of Examples 1 to 6, various commonly used additives, such as weathering stabilizers, antioxidants, lubricants, dispersants for inorganic fillers (various surfactants, fatty acid metal salts, fatty acid glycerin esters, etc.) were used. etc.), antistatic agents, etc. were not added, but these can be appropriately selected and used if necessary.

〔Effect of the invention〕

As explained above, according to the present invention, since an inorganic fungicide is added or mixed into the film, it is possible to effectively prevent the occurrence of diseases in crops and their transmission.

Claims (1)

[Claims] A thermoplastic resin used for hydroponic cultivation, the resin is an inorganic porous carrier holding a metal with a bactericidal effect.
A film for hydroponic cultivation containing 20% by weight.