DE2403206A1 - METHOD OF PROVIDING A REGULATED ENVIRONMENT FOR GROWING PLANTS - Google Patents

Description

"Method of providing a regulated environment for growing plants"

Priority : January 23, 1973, UK No. 3427/73

The invention relates to a method of providing a controlled environment for growing plants and especially for growing plants under controlled lighting conditions.

It is known that, for example, chrysanthemums and other plants bloom out of season by artificially shortening or lengthening the daylight. Be for this purpose

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them in greenhouses or in other environmental conditions drawn in which, on long days, daylight • is excluded or the Daylight can be reduced considerably, namely through the use of light-blocking covers. Black ones are often used for this purpose Plastic foils, such as polyethylene foils, are used, which contain soot. However, a disadvantage of using such films is that the heat absorption of the black foil, especially in summer, can lead to overheating of the plants growing underneath.

The present invention now provides a method for providing a controlled environment for growing Plants suggested, which consists in that the plants against incident daylight during desired Periods are shielded with the help of a two-layer cover made of plastic film, whereby the film layer, which is directed against the plants is black, and the layer which is directed against the incident light contains a heat reflective pigment.

The use of a two-layer cover according to the method of the invention is particularly effective in sunlight to a substantial reduction in the temperature in the space below the cover compared to such, in which the cover consists only of a black colored film. As already mentioned, the invention is special useful for providing regulated lighting, for example around chrysanthemums outside to bloom of the season. However, the subject of the invention can also be used to influence the growth of others Plants, including mushrooms, can be used.

The two layers of the film cover are preferably continuously connected to one another. Suitable -two-

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_ 3 -

Layered films can be produced particularly simply by pressing them out together, preferably using them of the same or very similar plastic material for the two layers and preferably by one common squeezing and blowing method · The heat reflective pigment is preferably white Pigment such as titanium dioxide. Polyethylene, including mixed polymers of ethylene with small proportions other monomers is understood is particularly suitable as a plastic material.

The plastic film cover can be supported in any desired manner. For example, there is one suitable covering device from a roll or rolls of the two-layer film, which is over a support frame for the foil is applied by placing the foil rolls over the to be covered during predetermined periods Plants are unrolled. The film can also be attached to a lightweight frame structure, which is placed over the plants or - during desired periods of the day via the lighting systems of a greenhouse. If desired, the cover films permanently attached to a support frame To shield daylight from the environment, the plants then, if desired, constantly illuminated by artificial light will.

If in this process a two-layer polyethylene film is used, the total thickness of the film is for general use typically from 50 to 200 pm. A film thinner than 50 µm is usually not sufficiently strong and a film that is thicker than 200 μm is uneconomical. A film with a total thickness from 65 to 100 µm has the advantage that it is easy to bend and can be draped easily. The black one

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Layer of film occupies at least 10 # of the total thickness to provide effective shielding, but not more than $ 60, or this will reduce the flexibility of the other layer. V / ffective and economic concentrations of the pigments in polyethylene consist, by weight, from 1 to 7 ^c fi carbon black and 5 to 20% of the V / crrae reflective pigment. The pigments can be added to the preliminary batch of the plastic mass, which is usually present in granules, and which is then pressed out together. For example, it has a suitable jointly pressed two-layer polyethylene film which was prepared by the tube process, a total thickness of 70 microns, the layer 35 schvrarze ρκι strong 1st and 3.2 Gev; .- / - containing> P.uss, and the heat reflective layer contains 12 wt .- ^ titanium dioxide.

A special embodiment of a cover according to FIG Invention is illustrated for example on the accompanying drawing. Here there are potted plants 1 on a growing table 2, which is covered from above and on all sides by lengths of a black / white two-layer film 3 with the white side of the film facing outwards. The foils are supported by a frame 4- supported, and the whole arrangement is in a greenhouse 5 · The covering foils are expediently grounded of rolls "attached to one or both ends or sides of the growing tables and from which they can be pulled off during the blackout periods and rewound if desired.

To demonstrate the temperature effect when covering plants, it was found that a two-layer black? / White film 70 µm thick, the black layer making up 50% of the total thickness and containing 3.2% by weight of carbon black, and the white layer contains 12 wt .- # titanium dioxide, one

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63% sun reflection on the white side. The reflection of sunlight, which is filtered when passing through a 3 ram thick glass window, has also been shown to be 63 % . The. The effect of the cover on reducing the temperature over the plants in comparison with a black film can be calculated using a simplified model as a basis. This consists of a semi-cylindrical greenhouse that is oriented north-south, with the plants being covered by a semi-cylindrical polytunnel, the radius of which is half as large as that of the greenhouse, and which runs in the middle of the greenhouse. The meteorological data used here are as follows: latitude 50 ⁰ N, month Mei, time 5 to 7 in the morning and 6 to 8 in the afternoon Central European time, mean altitude of the sun 18 °, ambient temperature 15 ⁰ C, still air, darkened sunlight. The diffuse sky radiation has been taken into account. Any other cooling or heating of the greenhouse or an exchange of air between inside and outside has not been taken into account.

The following mean temperatures for the two specified conditions were then found as follows (the true words lie between the specified):

1. The foil tunnel is closed at the bottom and at the ends, so that no air exchange between the planted area and the actual greenhouse took place:,

Black foil greenhouse temperature 24

Plant temperature 46 C

Black / white foil greenhouse temperature ^{21 0 C}

Plant temperature ^{31 0 C}

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2. There was free air circulation in the greenhouse instead and there were no temperature gradients:

Black foil greenhouse and plants 34- C Black / white foil greenhouse and plants 26 C.

It would have a very diminished effect when darkened The sun can be detected, but here too the plants are undesirably affected when a black film is used May be overheated.

The optical properties of a two-layer cover

(A) Made of polyethylene, a total thickness of 100 µm, where the black layer is 40 µm thick, and 5.2 Gev /.- J-ί Russ contains and the V / poor reflective layer 12 wt .- # Containing titanium dioxide were compared with three known masking materials that control the incidence of light used in growing plants. These passed

(B) made of a clear, multi-layer polyethylene film, which contained aluminum powder in the middle layer or layers, thereby making the film translucent and to make it reflective, (C) eir.er black foil, the outer surface of which has been silver-plated, to make them reflective, and (D) a clear film that is black on its inner surface was painted. When measuring the sun reflection and. The following values were found for the long-wave emission of these samples:

Sample AB C D

Sun reflection 57 % 31 % 10 # 3 ' %

Long wave emission 1.00 0.79 0.90 1.00

From these values it can be seen that with sample A, as used in the method according to the invention

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becomes, a much higher reflection of the solar radiation takes place than it is in any of the other samples of the 5'all and also an effective reflection of the absorbed Solar radiation occurs. This leads to a temperature increase below the cover A during exposure Sunlight that is much less than what happens when other covers are used.

Patent claims:

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Claims (1)

PATENT CLAIMS: 1J Procedure for providing controlled lighting for-growing plants, characterized that the plants are protected against incident daylight in the desired periods with the help of a two-layer cover shielded from plastic foil, whereby the foil layer, which is directed against the plants, is black and the film layer which is directed against the incident light is a heat-reflecting one Contains pigment. 2. The method according to claim 1, characterized in that the two-layer cover consists of polyethylene and has a total thickness of 50 to 200 µm, preferably 65 to 100 µm. J. The method according to claim 2, characterized in that that the black layer of the cover is 10 to 60 #, preferably about 50 #, which makes up the total film thickness. 4-. The method of claim 2 or J, characterized in that the black layer of the two-layer coverage of 1 to 7 wt .- ^ carbon black. 5 · Method according to one of claims 2 · to ■ '+, characterized characterized that the V / poor reflective layer of the Zv / eischichtenabdeckurr, · 5 to 20 wt .- ^ titanium dioxide cnt- ¹ S-gate direction to the Boroitstellunrr a nero-e lighting for wax ·) πάβ plants, characterized in, 409830/0438 that they are made of a two-layer cover made of plasticXolie consists, which is supported by a framework, the inner layer of the cover is black and the outer Layer contains a heat reflective pigment. 7. Apparatus according to claim 6, characterized in that the two layers of the cover are made of polyethylene consist and the total thickness of the cover from 50 to 200 jum, with the black layer from 10 to 60 #, preferably about $ 50. .'TH-SOHI Ä09830 / ÜA38 Blank page