JPH03180123A - Film for mulching cultivation - Google Patents

Abstract

PURPOSE:To prepare a mulching cultivation film enabling to effectively prevent the generation of the disease injuries of crops and the infections thereof by adding an inorganic porous carrier holding a metal having an antimicrobial activity to a thermoplastic resin film. CONSTITUTION:A film comprising a thermoplastic resin film containing 0.1-20wt.% of an inorganic porous carrier holding a metal having an antimicrobial activity. The employed thermoplastic resin is preferably branched low density polyethylene, straight chain low density polyethylene or ethylene- vinyl acetate copolymer on the points of cost and functions. The thickness of the film has a practical thickness range of 5-40mu but preferably 10-30mu on the points of cost and functions. Silver and copper are especially excellent as the antimicrobial activity on the points of functions such as the antimicrobial activity. The metal-holding degree of the film is generally in a range of 0.001-25wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a film used for mulch cultivation.

[Conventional technology]

Traditionally, films for mulch cultivation have mainly been used with a thickness of approximately 1.
0-30μ branched low density polyethylene (LDPE),
Transparent or black materials based on polyethylene such as linear low-density polyethylene (L-LDPE) are used. These films can suppress the evaporation of soil moisture, prevent the loss of heat of vaporization, and prevent the inflow of rainwater by simply placing the films in close contact with the soil surface. That is, it functions effectively in retaining soil moisture, increasing soil temperature, retaining soil swelling and softness, and preventing fertilizer from being washed away, thereby creating a soil environment favorable for crop cultivation. therefore,
The use of these films can promote and stabilize crop growth, allowing for early harvest and increased yields.

In addition, we also offer green films that raise soil temperature while suppressing the growth of weeds, and various reflective films (silver films and two-layered white and black films) that prevent pests from flying in and suppress soil temperature rises during the high summer season. (black and white two-layer film, etc.) are often used, but these films can also be used to create a favorable soil environment for crops.

[Problem to be solved by the invention]

As mentioned above, conventional mulch cultivation films can create a favorable soil environment for crops, but
On the contrary, there is a problem in that this soil environment becomes a suitable environment for soil pathogenic bacteria and promotes the occurrence and spread of diseases in crops.

This is because film mulching creates an environment in which soil moisture and soil temperature are suitable for pathogens (high humidity).

This is because it results in a high fA).

In other words, under mulch cultivation using transparent or black film, the soil temperature generally rises by an average of 3 to 5 degrees Celsius in the spring and an average of 5 to 7 degrees Celsius in the summer, compared to bare soil.
The temperature will be 0 to 40°C. In addition, instead of rainwater flowing from the soil surface, water moves from underground to the soil surface, so water is retained in the soil surface where most of the crop roots are distributed, creating a high humidity environment. It is formed.

In such a state, the water evaporated from the soil surface adheres to the inner surface of the film as dew water, and this becomes a perfect place for MA bacteria to operate. In addition, inorganic fertilizer components accumulate in the soil surface layer as water moves, and the soil surface layer is not compacted by rainwater, etc., and is in a swollen and oxygen-rich state with many air layers. This provides an ideal habitat for soil pathogens. Furthermore, moisture in the soil and water vapor evaporated from the soil surface move toward the planting holes in the mulch film and concentrate at the base of the crop, so the surface of the crop tends to remain constantly wet, which is where diseases can develop. Likely to happen. Particularly if the crop is damaged, diseases are more likely to occur in this area.

This invention was made in order to solve such conventional problems, and an object of the present invention is to provide a mulch cultivation film that can effectively prevent the occurrence and transmission of crop diseases. .

[Means to solve the problem]

The film for mulch cultivation provided by this invention is literally a thermoplastic resin film used for mulch cultivation, and the resin contains 0.1 to 20% by weight of an inorganic porous carrier holding a metal with a bactericidal effect. It is something.

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), and polyethylene such as ethylene-vinyl acetate copolymer (EVA), polyolefin resins such as polypropylene, polyamide resins, polyester resins, polyacrylic resins, polyvinyl chloride resins, etc. I can do it. 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 5 to 40μ, but from the viewpoint of cost and performance, 10 to 30μ 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 synthetic aluminum silicate, perlite, shirasu balloons, various synthetic and natural zeolites, weathered reef-building coral grains, seviolite, 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 kinds of zeolite and weathered reef-building coral grains are suitable from the viewpoint 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 silver is retained in zeolite, the amount is 0.1 to 15% by weight, preferably 0.1 to 5% by weight.

When the metal is retained in the inorganic porous carrier, either an ionic bonding method or a coating method can be used.

Among these, 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. One 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 set to 0.
．． The reason for setting the upper limit at 1% by weight is that if it is less than this, the sustainability of the bactericidal effect will be reduced, and the reason why the upper limit was set at 20% by weight is that if it exceeds this, not only will the strength of the film decrease, but also the strength of the film will decrease during film forming. This is because problems such as foaming will increase. The preferred content is 0.1 to 5% by weight.

The film is generally a transparent film, but may be colored black, green, silver, white, etc. As for the coloring method, it is desirable to form a film by mixing colorants in terms of cost and performance. You may print it if necessary. For silver color, aluminum vapor deposition or aluminum foil lamination can also be used.

Single layer, two layers such as white/black, silver/black, or transparent/
Three layers such as silver/transparent 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). The second and third layers may be made of the same resin or may be made of different resins bonded together. In the case of laminated layers, at least the inner layer in contact with the soil should contain a fungicide.

Furthermore, the film may be provided with minute holes or slits with a diameter of several 111 meters or less in order to lower the temperature of the roots due to the heat of vaporization.

[Effect]

When the above-mentioned mulch cultivation film is spread in close contact with the upper surface of the soil, its bactericidal effect effectively prevents the occurrence and transmission of diseases in crops, but what is the mechanism by which this bactericidal effect is achieved? There are various theories regarding this. 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] [1] A bactericide was added to a thermoplastic resin in the following manner, the mixture was kneaded and granulated, and then molded to a thickness of 15 μm.
Transparent single layer films with a width of 950+nm, ie the films of Examples 1-3, were made.

(1) Thermoplastic resin: LLDPE (Yukalon LL, UA420 manufactured by Mitsubishi Yuka) (2) Disinfectant: 0.3 mol silver nitrate aqueous solution of 8-type zeolide with an average particle size of 5 μ and a molar ratio of SiO□/Al2O3 of 10 Ag-zeolite was converted into Ag-zeolite through an ion exchange reaction in the medium, and then filtered, washed with water to remove excess silver ions, and then dried at 100 to 110°C, resulting in a silver content of 4 weight. % zeolite.

(3) Amount of fungicide added: Film of Comparative Example 1: No additive Film of Example 1: 15 t [J amount % Film of Example 2: 5 wt% added Film of Example 3: 0.2 wt% Addition (4) Kneading of thermoplastic resin and disinfectant: using a Banbury mixer.

(5) Molding the film by a general inflation molding method. (Extruder 65 mm φ, die 350 mm φ) [+1] Cucumbers were cultivated in the following manner using the transparent single-layer films of Examples 1 to 3, and the occurrence of diseases (late blight) was investigated.

(1) A high ridge with a ridge width of 60 cm and a length of 10 m was made, and the films of Examples 1 to 3 and the film of Comparative Example 1 were spread thereon. For each film, 3 ridges were used as the test area, and a total of 1
Two ridges were established.

(2) Fertilizer has nitrogen, phosphorus, and potassium components of 13-24-2
0kg/10a was applied.

(3) The cucumber variety used was Summer Autumn Setsei No. 2.

(4) Each film had one planting hole with a forest interval of 60 cm and a hole diameter of 10 cm, and the seeds were planted there.

(5) R culture was planted on April 20th, the vinyl tunnel was covered until May 5th, and harvesting started from mid-May.

Table 1 shows the above survey results, and the survey results are expressed as the rate of diseased strains (%) for each survey date.

Phytophthora blight, which is a type of disease that frequently occurs on cucumbers, is caused by Phytophthora bacterium. The source of infection is zoospores, and infection occurs under conditions of high temperature and humidity. The zoospores swim in the soil or in the water of condensation adhering to the inner surface of the film and invade the roots and subsurface parts of cucumber plants, causing infection. The whole body of the infected cucumbers wilts and dies, and the roots are also observed to rot.Whether or not the plant is a disease-free plant was judged based on the presence or absence of such phenomena.

As is clear from Table 1, in the film of Comparative Example 1, disease onset was observed from early June when it started to rain heavily, and it was found that the infection was remarkable and the rate of diseased plants was quite high. On the other hand, in the films of Examples 1 to 3, the development of diseases was relatively slow, and the spread was very slight. Therefore, the incidence of disease was also very low.

[Examples 4 to 6] [I] A black mixed raw material obtained by adding a bactericide and a black coloring agent to a thermoplastic resin as well as a white mixed raw material obtained by adding a bactericide and a white coloring agent to a thermoplastic resin in the following manner. are kneaded and granulated, and then molded to obtain a white layer with a thickness of 15 mm.
μ, black layer thickness 15μ, total thickness 30μ, width 950
A black-and-white two-layer film of Example 4N6 was prepared.

(+) Thermoplastic resin: LLDPE (Mitsubishi Yuka Type Yucalon LL, UA420) (2) Disinfectant: Coral Sand (Kaze) with an average particle size of 5μ.

After desalinating the coral sand by washing with water, it is activated by heating and drying at 200 to 400° C. for 2 hours under reduced pressure to decompose 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 allowing it to stand 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: Added no additive Film of Example 4 = 15% by weight Film of Example 5: Added 5% by weight Film of Example 6 = Added 0.2% by weight The fungicide was added equally to both the white and black layers.

(4) Black colorant and Its addition ffi: Any of Examples 4 to 6 Carbon black 3 on the lume Weight% addition (manufactured by Tokyo Ink) Carbon black 30% by weight Containing masterbatch [PEX 3286 Black 3S] for) (5) White colorant and Addition amount: Any of Examples 4 to 6 Titanium white (acid) Titanium chloride) 10% by weight added (Tokyo Ink titanium foam) master containing 40% by weight Hatsuchi [PEX3009J Ho white] used) (6) Thermoplastic resin, fungicide and kneading of colorant: using a Banbury mixer.

(7) Forming of film: A so-called general die lamination inflation molding method is used in which white and black raw materials are melted and fed from separate extruders to one two-layer die. (Extruder 50 mm φ x 2 units, 350IIlfflφ two-layer die) [11] Using the black and white two-layer films of Examples 4 to 6, radish was cultivated in the following manner, and the disease (yellowing that often occurs during the high temperature period) was removed. We investigated the occurrence of this disease.

(+1 ridge A high ridge with a width of 60 am and a length of 10 m was made, and the films of Examples 4 to 6 and the film of Comparative Example 2 were spread on it. Three ridges of each film were used as test areas, and a total of 1
Two ridges were established.

(2) Fertilizer is 2020-1O with nitrogen, phosphorus, and potassium components.
-15/IOa was applied.

(3) The radish variety used was a disease-resistant, early-season variety.

(4) Each film has a plant spacing of 30 cab and a row spacing of 45 cm.
Two rows of planting holes with a hole diameter of 6CO+ were made, and the seeds were sown there.

(5) Cultivation: Seed was sown on August 26, 1999, and harvested on October 20, 1999.

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

Note that yellow chlorosis is caused by Fusarium C, which is a type of filamentous fungus. This fungus is a long-lived thick WA spore that continues to survive in the soil for several years or more, and when the roots of radish come near, it releases germ tubes (W!, dye source) and invades the roots.
It gets infected. The leaves of daikon radish affected by yellowing disease wilt, turn yellow, and die. Whether the plant was a diseased plant or not was judged based on the presence or absence of such a phenomenon.

As is clear from Table 2, in the film of Comparative Example 2, 9
The disease appears from around mid-month, and by mid-October, about 1/2
It was infected with 4 strains. On the other hand, in the films of Examples 4 to 6, the occurrence of disease was slow and was small. In addition, almost no transmission of the disease to other strains was observed.

[I[+] Same <Chinese cabbage was cultivated in the following manner using the black and white two-layer films of Examples 4 to 6, and the occurrence of disease (soft rot) was investigated.

(1) Create a high ridge with a ridge width of 60 cab and a length of 10 m,
The films of Examples 4 to 6 and the film of Comparative Example 2 were stretched. For each film, three ridges were used as the test area, and a total of 12 ridges were provided.

(2) Fertilizer is 27-18-2 with jisso linpotassium component
2 kg/IOa was applied.

(3) The Chinese cabbage variety used was 60 days resistant to Nagako.

(4) Two planting holes with a plant spacing of 40 cm, a row spacing of 45 cm, and a hole diameter of 6 cm were provided in each film, and the seeds were planted in these holes.

(5) Cultivation was carried out by sowing and raising seedlings on August 10, 1999.
Planting was done on the 25th of October, and harvesting began on the 20th of October.

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

Note that soft rot is a disease caused by bacteria of the genus Erwinia. This bacterium remains viable for long periods of time under humid conditions and at temperatures below 20°C, and particularly invades through damage caused by pests and wounds caused by wind and rain. Soft rot disease tends to develop under hot and humid conditions, and the entire stems and leaves of Chinese cabbage affected by this disease become water-soaked, soften, and rot. Whether or not the plant is a disease-free plant was determined by the presence or absence of such a phenomenon.

As is clear from Table 3, in the film of Comparative Example 2, 9
Diseases appear from around mid-month, and by mid-October, about 1/2
It was infected with 4 strains. On the other hand, in the films of Examples 4 to 6, the occurrence of disease was slow and was small. Also,
Almost no transmission of the disease to 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 crop diseases and their transmission.

Claims (1)

[Claims] A thermoplastic resin film used for mulch cultivation, the resin containing 0.1 to 20% by weight of an inorganic porous carrier holding a metal having a bactericidal effect.