CH657012A5 - METHOD AND DEVICE FOR IMPROVING PLANT GROWTH. - Google Patents

Description

The present invention relates to a method and a device for improving the growth of plants in greenhouses and climatic cells by subjecting them to intermittent illumination.

For the purposes of this text, “greenhouses and climatic cells” will be understood to mean all enclosures in which one artificially recreates, partially or entirely, the conditions specific to the cultivation of plants, in particular the conditions of temperature, hygrometry and lighting.

The use of greenhouses and climatic cells makes it possible to grow plants outside their usual growing season, for example in winter, while the usual growing season is spread, generally, over the spring / summer period.

To achieve this, it is of course necessary to recreate inside the greenhouses or climatic cells the optimal conditions suitable for ensuring satisfactory development of the plant, in particular the conditions of temperature, hygrometry and appropriate lighting. The conditions to be used will of course be very different, depending on whether one wishes to cultivate crops of temperate climate, such as wheat, or crops of tropical or subtropical climate, such as cotton or soybeans.

If the establishment of appropriate conditions, with regard to temperature and hygrometry, does not present insurmountable difficulties, it is not the same for the establishment in greenhouse and climatic cell of the appropriate lighting conditions, especially when you want to recreate the lighting conditions necessary for the cultivation of tropical or subtropical plants. Indeed, the lighting system must then satisfy several very restrictive conditions:

- it must provide the plants with an illumination which can reach, if necessary (that is to say, depending on the crop), very high values,

reaching and even exceeding 100,000 Lux at plant level,

- the lighting must be distributed very evenly over the growing area,

- the lighting system must be placed at a sufficient height, above the growing area, so that it does not hinder either the growth of the plants or the manipulations necessary for their cultivation,

- finally, in the case of greenhouses, the lighting system must obscure as little as possible the entry into the greenhouse of sunlight from external sources.

25 For this, a set of fluorescent tubes is usually used, fixed to the upper part of the greenhouse or of the climatic cell, these tubes being parallel to each other, contiguous to each other and situated in the same horizontal plane, at very short distance. from each other, so as to constitute together a light source 30 of rectangular shape, the vertical projection of which on the lower part of the greenhouse or of the climatic cell represents the surface to be lit. As an indication, to light a ground surface of 6 m x 6 m, one thus uses 180 fluorescent tubes of 215 watts each, located at 0.90 m above the zone in which the 35 plants will be placed. The main disadvantage of this system is that despite the use of a large number of tubes, it is difficult to obtain an illumination (luminous flux) of up to 40,000 Lux at plant level, which is completely insufficient when wants to grow tropical or subtropical plants. Another drawback of this system is that it requires a large number of fluorescent tubes, and therefore entails, on the one hand, a significant investment and, on the other hand, also a very significant energy consumption. This significant energy consumption results in a significant release of heat inside the greenhouse or 45 climatic cell and it is therefore necessary to provide a larger temperature regulation installation to maintain the latter at the desired value. . Finally, with such a system, in the case of a greenhouse, the sunlight is almost completely obscured and therefore the light of external origin is totally unused.

n / a The replacement of the tubes by more powerful lamps, such as for example discharge lamps, whose unit power can be 1000 and even 2000 watts does not give any satisfaction either, because then arise problems of lack of 'uniformity of lighting and even in this case, it is hardly possible to obtain more than 50,000 Lux at plant level. The drawbacks mentioned above and relating to the consumption of energy and the dissipation of this energy in the form of heat inside the greenhouse or the enclosure exist of course also when using lamps in place of fluorescent tubes. Due to these 60 insufficiencies of lighting in greenhouses or climatic cells, it is observed that plants cultivated under such conditions generally have a different appearance from those cultivated in the open field, under the optimal conditions relating to these plants: those cultivated in greenhouse or climatic cell are very often faded, more fragile and 65 less green than those cultivated in open field. These differences are particularly troublesome when it is desired to test in the greenhouse or climate cell pesticide products intended for agriculture and which will therefore, as a general rule, be used for milking

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in the open field; it is especially necessary for such experiments that greenhouse trials are as similar as possible to field trials.

An object of the present invention is to remedy the drawbacks of known techniques.

Another object of the invention is to promote to the maximum the phenomena of photosynthesis in plants.

Another object of the invention is to develop to the maximum the ability of plants to assimilate carbon dioxide from the air and to produce oxygen.

Another object of the invention is to produce plants in the greenhouse whose growth is as close as possible to growth in the open field, both in terms of size and size, vigor, branching (branching), budding, flowering.

Another object of the invention is to produce plants with a high chlorophyll content.

Another object of the invention is to provide a method of growing plants in a greenhouse using equipment that is as simple as possible and that consumes a minimum of energy.

Another object of the invention is to provide a method of cultivating plants in which the light energy incident on the leaves is distributed in a homogeneous manner, whatever the inclination of the leaves and whatever the situation of the leaves on the plant (outside or inside the foliage).

Another object of the invention is to avoid as far as possible non-visible radiation, especially ultraviolet radiation. Indeed, in addition to the dangers that such radiations give rise to when meeting people taking care of plants, these radiations are often the cause of degradation of the agrochemicals applied to plants, which annihilates the beneficial effect of these products and disturbs the experiments if they are experiments.

Other objects and advantages will become apparent from the following description.

It has now been found that these objects can be achieved by the method of the invention.

This process is therefore a process for improving the growth of plants in greenhouses or climatic cells and it is characterized in that:

- the plants are arranged on a substantially flat and horizontal surface,

- the plants are lit using a mobile light source located above the plants and remaining in a substantially horizontal plane and parallel to the surface where the plants are arranged,

The light source mainly comprises radiation of wavelength between 380 nanometers and 800 nanometers, preferably between 450 and 750 nanometers,

- the light source moves above the plants in a regular movement so as to create intermittent lighting at the level of the plants.

Various methods of carrying out the process of the invention can be carried out.

In the accompanying drawing,

fig. 1 is a schematic plan view of a first embodiment of the device of the invention, and FIG. 2 is also a schematic and plan view of the second embodiment.

According to an advantageous modality, the plants are arranged on a surface of substantially rectangular shape and the light source is also in the shape of a rectangle, one of the dimensions of which is substantially equal to one of the sides of the zone of substantially rectangular shape with enlighten.

Also advantageously, the light source moves in a direction parallel to one of the sides of the rectangular area to be lit (the light source having a common dimension with the other side of the area to be lit).

In practice, during its movement, the extended light source gradually illuminates all the points of the substantially rectangular horizontal surface along which the plants are arranged.

5 The light source preferably moves in a regular movement at constant speed, either in one direction or in another. It can be a back and forth movement.

In the case where the surface to be lit, which is rectangular, would in fact consist of a succession of rectangles which can io form a closed circuit, the light source could then move along each of these rectangles and also travel through it. - even a closed circuit. In such a situation, for a given rectangle to be lit, the light source moves above it always in the same direction.

As indicated above, the extended light source generally comprises several lamps. These lamps are advantageously arranged inside a reflective casing of substantially rectangular section.

FIG. 1 illustrates, schematically, an embodiment of the invention according to which an extended light source, constituted by a reflective casing (1) in which are arranged 4 discharge lamps of 1000 watts each (2), shown in dotted lines inside the casing, moves in the direction represented by the arrows, above the bench seat (3), of substantially rectan-gular shape, on which the plants to be cultivated will be arranged (not shown in FIG. 1 ). The extended light source is moved in a uniform back-and-forth motion, first from an extreme position A to the opposite extreme position B, then from B to A, etc.

3o For reasons of simplification, we have not shown in Figure 1 the electrical connection means for conducting the electric current to the lamps, nor the mechanical means for moving the light source. In practice, it is advantageously possible to provide for this two guide rails situated above the longitudinal sides of the bench seat (3) and to install rollers at the two longitudinal ends of the casing (2), so that this casing can be move on these guide rails in the direction indicated.

FIG. 2 represents another embodiment, according to which the reflector housing (1), situated above the bench seat (3), is movable in the directions represented by the arrows, comprises 10 discharge lamps of 1000 watts each shown in dotted lines. The light source, constituted by the lamps and the casing, moves in a uniform movement from A to B then from B to A according to a back and forth movement. It is of course possible to use a higher or more limited number of lamps than that shown in FIGS. 1 and 2 and the invention should therefore not be limited to the devices represented by these figures.

As is well understood from the exemplary embodiments 50 illustrated by these figures, the method according to the invention makes it possible to regularly sweep the whole of the rectangular horizontal surface mentioned above by providing it very uniformly with the quantity of lighting.

The distance between the plane in which the lu-55 miner source moves and that of the rectangular horizontal surface on which the cultures are placed can be determined according to the power of the light source and the desired luminous flux at plant level . Thus, as an indication, for a distance between planes of 1.6 m, the light source represented in FIG. 1 brings, at 60 each passage, 50,000 Lux to the plant situated at its vertical, whereas that represented by the figure 2, more specifically intended for a climatic cell, provides nearly 100,000 Lux for the passage.

In the case of a greenhouse, it will be observed that such a system produces only a very small occultation of the external light which can therefore be advantageously used in addition.

The speed of movement of the light source can be chosen within wide limits; however, it has been observed that whatever crops are grown, the best results have been obtained.

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for speeds ranging from 2 m min to 8 m / min and preferably for the speed of 4 m.'mn.

The periodicity of passage of the light source can also vary within wide limits, it is advantageous however to effect a passage of the light source above each plant per period of 45 seconds to 3 minutes, preferably one passage per period from I to 2 minutes.

The following examples, given without limitation, illustrate the invention and show how it can be implemented.

Example 1

For a greenhouse test, a light source of 4 x 1000 watts is used as shown in FIG. 1. The deflector (1) (or lampshade), serving as a lamp holder, is equipped, on its two ends, casters (not shown) allowing it to move in the direction shown by the arrows on rails (not shown) horizontal, located 1.6 m above the long sides of the bench (3) whose length is 6 m. This light source only emits radiation in the visible range.

On this bench, seeds of wheat, mustard and soybeans are sown in terrines, which are maintained under the usual conditions of temperature and humidity. The lamps are on. The light source moves back and forth over the bench at a speed of 4 m / min from 7 a.m. to 9 p.m. It is off the rest of the time. After 35 days under these conditions, it is observed that the plants obtained have an appearance quite similar to that of the same plants obtained in the field.

Example 2

Example 1 is reproduced by growing bean seedlings in pots under lighting from the start of seed sowing.

Half of the bean plants are subjected to intermittent lighting (mobile light source) as in Example 1. The other half is subjected to identical lighting from the point of view of the light source, but not intermittent (fixed light source) ).

After 15 days, 15 leaves are taken from each of the two bean populations and the chlorophylls A and B are extracted with an acetone water mixture, then these chlorophylls are assayed by spec-trophotometry.

5 It is found that plants with fixed lighting contain 0.67 mg of chlorophyll per gram of bean leaf while plants with mobile lighting contain 0.89 mg g, which is about 33% more.

Example 3

Example 1 is reproduced with various kinds of plants by carrying out a comparative experiment with plants subjected to fixed lighting by the same lamps.

15 days after the start of the experiment, the following observations are made on beans and soybeans:

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Bean:

The average size of plants obtained under mobile lighting is reduced by 35% compared to the size of plants obtained under fixed lighting. The plants obtained under mobile lighting are therefore shorter but more vigorous, very green and similar to those obtained in the open field; the plants obtained under fixed lighting are, on the contrary, etiolated, that is to say that they have excessive size and thinness; moreover, they have a strong tendency to lodging, the stem not having enough vigor to stand straight.

Soy:

The average size of plants obtained under mobile lighting is reduced by 25% compared to plants obtained under fixed lighting. But these plants obtained under mobile lighting are more vigorous and have a port or maintenance as well as a color similar to those of plants obtained in the open field.

Panisse (echinochloa crus galli):

Germination, or emergence, is obtained in 4 days after sowing under

35 mobile lamps and in 8 days after sowing under fixed lamps.

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1 sheet of drawings

Claims (11)

657,012 1. Method for improving the growth of plants in greenhouses or climatic cells, characterized in that: - the plants are arranged on an approximately flat and horizontal surface, - the plants are lit using a mobile light source located above the plants and remaining in a horizontal plane parallel to the surface where the plants are arranged, - the light source mainly comprises radiation of wavelength between 380 nanometers and 800 nanometers, - the light source moves above the plants in a regular movement so as to create intermittent lighting at the level of the plants. 2. Method according to claim 1, characterized in that the plants are arranged in a rectangular-shaped surface and the light source is also in the shape of a rectangle, one of the dimensions of which is equal to one of the sides of the zone rectangular in shape to light up. 2 3. Method according to one of claims 1 or 2. characterized in that the light source moves in a direction parallel to one of the sides of the rectangular area to be illuminated, the light source having a common dimension with the other side of the area to be lit. 4. Method according to one of claims 1 to 3, characterized in that, during its movement, the extended light source gradually illuminates all the points of the rectangular horizontal surface along which the plants are arranged. 5. Method according to one of claims I to 4, characterized in that the light source moves at constant speed. 6. Method according to one of claims 1 to 5, characterized in that the light source moves in a back-and-forth movement. 7. Method according to one of claims 1 to 5, characterized in that the area to be lit consists of a succession of rectangular areas. 8. Method according to claim 7, characterized in that the light source travels in a closed circuit. 9. Method according to one of claims 1 to 8, characterized in that the light source passes over the plants once per period of 45 seconds to 3 minutes. 10. Method according to claim 9, characterized in that the light source passes over the plants once per period of 1 to 2 minutes. 11. Device for the implementation of any one of claims 1 to 10, containing the constituents mentioned in this or these claims.