Patent Application
20120311925
The invention relates to the cultivation of insect pollinated plants in a greenhouse environment. In more particular, the invention relates to a lighting device and a method of illumination designed to enhance insect pollination in plants, such as the tomato.
It is a well known fact that some plants are insect pollinated, the most notable agricultural plant belonging to this category being the tomato. The reproduction of these plants and fruit production depends on the pollination that in natural conditions is conducted by insects and wind. In greenhouse environments mechanical vibrators and hormone treatments of plants have been employed in the prior art to guarantee sufficient levels of pollination. These methods lead to poor quality of fruit. A failed pollination can lead for example to deformed fruit. Introducing insects into greenhouse environments increases crop yield but is quite expensive, as greenhouse gas discharge lights kill the insects quite frequently with their heat, and new insects need to be frequently introduced.
It is also known in the prior art that insect vision is very sensitive to ultraviolet radiation, please see e.g. Limits to salience of ultraviolet: lessons from colour vision in bees and birds, Kevan et al., which is cited here as reference. It is also known that honey bees and bumble bees use motion parallax in their vision, please see Lehrer M. 1998, “Looking all around: honeybees use different cues in different eye regions”, Journal of Experimental Biology 201:3275-3292, which document is cited here as reference. As the insect flies over a field of flowers, the flower closer to the insect than its background appears to move faster than the background, thereby creating a relative motion between the flower and the background. In nature the flowers are nearly always moving, typically due to wind, and can thus be easily observed by the insects. In a greenhouse environment there is typically no wind, which makes it difficult for insects to detect the flowers.
The UV feature of insect vision has been utilized by man in the prior art, for example in WO 2009/040528, which is cited here as reference. This publication shows the photomanipulation of insects with Light Emitting Diode (LED) at wavelengths of 353 nanometers (nm), 345-375 nm, 315-400 nm. The insects are photomanipulated towards the light, so that they could be trapped. This device is used in a restaurant environment, so that the customers would not be disturbed by the insects.
It is a well known fact that different flowers reflect light differently.
There are serious disadvantages in the prior art. The aforementioned spectral observations have been used only for trapping insects as pests. Also artificial illumination solutions for plants of the prior art, of which WO/2011 033177 is perhaps the most developed, have addressed the enhancement of only photosynthetic growth of the plants, not their reproduction or fruit production. It is very difficult for pollinating insects to find flowers in greenhouses when it is winter, cloudy weather or otherwise dark, and/or when the air stands still. Realising natural pollination activity that would be as high quality as the natural process, or even higher quality in greenhouse environments is therefore a substantial problem burdening the prior art.
It is an object of the invention to solve the aforementioned disadvantages. The invention under study is directed towards a system and a method for effectively illuminating plants so that they achieve the desired photosynthetic growth and are pollinated more frequently by insects.
A further object of the invention is to provide an illumination device that is harmless to the pollinating insects in a greenhouse environment.
In one aspect of the invention the plants are illuminated with a lighting device that comprises LEDs and provides strong emission peaks at wavelengths that coincide with the reflectivity of the flowers being cultivated. This has the effect that the insects can see the flowers better, and therefore find them more easily, which increases the efficiency of pollination by the insects. A further improvement to this aspect is to choose those wavelengths for emission peaks that have a high reflectivity from flowers and/or high sensitivity in the insect vision. The best effect is achieved when the aforementioned high reflectivity and high vision sensitivity coincide. This is the preferred emission wavelength for a pollination enhancing lighting device as it increases the visibility of the flowers in the eyes of the insect maximally.
The wavelengths that are typically suited as emission peaks are for example 348 nm, 375 nm, 435 nm, 533 nm, 538 nm with an error range of ±10 nm. The light device is typically realized with LEDs and/or quantum dots. A quantum dot is a semiconductor whose excitons are confined in all three spatial dimensions.
The peak wavelengths may vary depending on the plant species being cultivated and the insect used to cultivate the said plant. For example (B. terrestrisdalmatinus and B. terrestrissassaricus) exhibited spectral peaks at 348 nm, 435 nm and 533 nm and 347 nm, 436 nm and 538 nm, please see Skorupski P., Döring T. F. & Chittka L. 2007, “Photoreceptor spectral sensitivity in island and mainland populations of the bumblebee, Bombusterrestris”, Journal of Comparative Physiology A 193: 485-494, which is cited here as reference. B. impatiens has its photoreceptor spectral sensitivity peaks at 347 nm, 424 nm and 539 nm, please see Skorupski P. & Chittka L. 2007, “Photoreceptor spectral sensitivity in the bumblebee, Bombus impatiens (Hymenoptera: Apidae)”, Plos ONE 5: 1-5, which document is cited here as reference. Any or all of the aforementioned peaks could be used as center wavelengths for light emitter spectral peaks of the invention.
Another aspect of the invention combines the aforementioned light device with a light device that enhances the photosynthetic growth in plants. This light device typically has a peak in the blue emission, low green and/or yellow emission, and a peak in the red and/or far red emission. This maximises photosynthetic growth as it coincides with the absorption peaks of
A horticultural light device in accordance with the inventionis characterised in that the said light device is arranged to emit at least one spectral peak at a wavelength that coincides with increased reflectivity of flowers of pollinating plants.
A plant cultivation methodin accordance with the inventionis characterised in that the pollinating plants are illuminated with a light device emitting at least one spectral peak at a wavelength that coincides with increased reflectivity of flowers of said pollinating plants.
The “coincidence” in this application is understood as the positioning of spectral peaks that aims to maximize the incoming photons from the flower to the insect eye, and ultimately maximize the neurological vision signal that the insect eye generates from the photons. Therefore the peaks do not need to mathematically exactly coincide, in accordance with the invention the peaks need only to coincide to a degree that sufficiently maximizes the neurological vision signal in the insect eye.
The said aforementioned increased reflectivity and/or sensitivity is understood to exceed the 90%-, 80%-, 70%-, 60%-, 50%-, 40%- or 30%-level of maximum of said reflectivity and/or sensitivity in the UV (300-400 nm) to far red (700-800 nm) band. For example if both the reflectivity and the sensitivity would be at 70% level of maximum, the end visual signal detected by the insect would be 0.7*0.7=0.49, i.e. roughly half of the signal that exact coincidence of maximum peaks could produce. This is most probably a sufficient level to assist the insects in pollinating the plants very significantly.
The plant illumination device and method of the invention has the advantage that the LED and/or quantum dot based design is harmless to the pollinating insects. Prior art light devices relying on electric discharge typically attract insects, but also heat to extreme temperatures, killing many pollinating insects that are drawn close to the prior art light device. A further advantage of the invention is that as the insects see the flowers better; pollination efficiency is increased, leading to more enhanced reproduction by the plants, higher volume and quality fruit production and an increase in crop. The better survival rate and improved vision have a synergistic added advantage: the insects are known to be capable of learning to operate in different illumination wavelengths and conditions. However, if the insects are killed by hot lamps very early on, no learning will have taken place. A light device that is not lethal to insects also adds to improved pollination by its effect of allowing more educated insects to pollinate the plants more effectively than ever before. The light device provides also for better rested insects as the insects find to their nest easier with the inventive light solution than without it. As the insects are capable of learning, it is possible that the insects can work quite effectively in illumination conditions where the peak wavelength of the illumination is not at maximum sensitivity, when they are provided with the chance to adjust to the lighting conditions.
LEDs of the invention provide also an improvement to current solution using HPS and HID (High Intensity Discharge) due to their capability of easy spectrum in-situ tuning, e.g. UV LEDs can only be turned on during a pollination event, i.e. when pollinating insects are present near the plants. When turned off UV light does not assist harmful insects, such as pests, to find plants. This is not possible in HPS and HID lamps of the prior art. Producing UV light also consumes more energy and therefore it is beneficial to use that spectrum off when not used.
An even further advantage of the invention is that as the light device of the invention enhances both reproduction and growth, this enhancement has a synergistic improvement in crop levels that goes beyond the levels that could be achieved by using either one lighting solution individually or separately. Even further, the invention has the advantage that fruit production becomes possible in polar regions, cloudy weather conditions and winter seasonal times that have been impossible to use for fruit production before due to low natural light levels.
In addition and with reference to the aforementioned advantage accruing embodiments, the best mode of the invention is considered to be the use of a LED lighting device having emission peaks matching the photosynthetic relative absorption peaks of green plants, and the relative reflectance peaks of flowers of plants being cultivated and the relative sensitivity peaks of the insect's vision being used in the pollination.
The file of this patent contains at least one drawing executed in color. Copies of this patent with color drawings will be provided by the Patent and Trademark Office upon request and payment of the necessary fee.
In the following the invention will be described in greater detail with reference to exemplary embodiments in accordance with the accompanying drawings, in which
Some of the embodiments are described in the dependent claim
From the
Preferably, the said increased reflectivity and/or sensitivity exceeds the 1/√2 of maximum of said reflectivity and/or sensitivity in the UV to far red band in some embodiments of the invention. In some embodiments at coincidence wavelength the reflectivity and/or sensitivity exceeds the 90%-, 80%-, 70%-, 60%-, 50%-, 40%- or 30%-level of maximum of said reflectivity and/or sensitivity in the UV (300-400 nm) to far red (700-800 nm) band.
The light device is typically arranged to comprise at least one LED and/or quantum dot, or be composed entirely of LEDs and/or quantum dots. This design choice allows for greater spectral design freedom needed in optimizing the emission peaks to match the aforementioned flower reflectivity and insect eye sensitivity spectral peaks. Furthermore, this emitter technology has the added effect that these lighting devices do not heat to levels that are lethal to the pollinating insects.
The light device and the method is/are typically used in a greenhouse and/or indoor environment where insect pollinated plants are cultivated, but can also be used outdoors. In phase 210 the light emission is directed towards flowers in the greenhouse. In phase 220 the pollinating insects are released into the greenhouse. Typically these insects are honeybees and/or bumblebees.
In phase 230 a high number of photons are reflected from flowers at wavelengths of high insect vision sensitivity. This creates an environment where the insects observe the flowers extremely easily and therefore discover pollination targets as effectively as possible in phase 240.
The increased observability of pollination targets by the insects leads to enhanced pollination and thereby the crop being cultivated increases in yield substantially in phase 250. This method is preferably used in combination with alight device and method that optimizes photosynthetic growth. Preferably the light device used in combination with method 20 is a horticultural lighting fixture comprising at least one Light Emitting Diode (LED) having a first spectral characteristics including a peak in the wavelength range from 600 to 700 nm and arranged to exhibit a full width at half maximum of at least 50 nm or more and a second spectral characteristics with a maximum of 50 nm full width at half maximum and arranged to exhibit a peak wavelength in the range from 440 to 500 nm.
Furthermore in some embodiments of the invention at least a part or the whole of the emission at wavelengths of 500-600 nm is minimized and/or omitted and/or reduced below the intensity in 400-500 nm band and below the intensity in 600-700 nm band. As
The emission can be achieved by powering LEDs and/or quantum dots electrically and/or by optical up-conversion in accordance with the invention. In optical up-conversion short wavelength radiation is absorbed and then optically re-emitted at a longer wavelength. Quantum dots and/or phosphorus can be used to realize the wavelength up-conversion of the invention. In one embodiment that is especially preferable the far red radiation (700-800 nm) is produced by for example europium-cerium co-doped BaxSryZnS3 phosphors and/or cerium doped lanthanide oxide sulfides. These phosphor and sulfide types have emission peak maxima between 650-700 nm wavelength region and exhibit also broad (50-200 nm) full width at half maximum and therefore also produce light emission at higher wavelength, i.e., above 700 nm wavelength range.
In one embodiment, all or part of the emission at a frequency of 600-800 nm is generated using a whole or partial wavelength up-conversion of the LED chip radiation power.
It should also further be noted that the embodiment 20 can be readily permuted and/or combined with any of the embodiments 30, 31, 32, 40, 50, 60, 70, 71 and/or 80 in accordance with the invention.
Preferably the at least one LED 101, 102, 103, 104 produces an emission spectrum that has the peaks at wavelengths that coincide with high photosynthetic absorption, high flower reflectivity and/or high insect vision sensitivity as explained before in some embodiments.
It should also further be noted that the embodiment 30 can be readily permuted and/or combined with any of the embodiments 20, 31, 32, 40, 50, 60, 70, 71 and/or 80 in accordance with the invention.
Furthermore any light emitter design from EP 11158698.8, of the inventor and applicant can be combined with embodiment 30. This document is cited here as reference.
The LED can typically be only driven by electric power. The quantum dots can be driven by electric power to produce light emission, but in some embodiments all or some quantum dots can be used as wavelength up-converters of absorbed optical radiation also. Preferably some quantum dots are of different size in some embodiments, as a different dot diameter implies a different emission spectrum.
Preferably the at least one LED 101 and at least one quantum dot 110, 120, 130, 140, 150, 160 produce an emission spectrum that produces the peaks at wavelengths that coincide with high photosynthetic absorption, high flower reflectivity and/or high insect vision sensitivity as explained before in some embodiments.
All or some of the quantum dots 110, 120, 130, 140, 150 and 160 are typically manufactured from any of the following alloys: cadmium selenide, cadmium sulphide, indium arsenide, indium phosphide and/or cadmium selenide sulphide in some embodiments. In one special exemplary embodiment of the invention CdSe—ZnS (core-shell) quantum dot nano particles with average particle size of 6.6 nm with approximately +/−0.5 nm particle size distribution were mixed with a two component silicone encapsulant resin. The mixing ratio was 0.2 w-% of nanoparticles in the silicone resin. The resin containing nano particles were dispensed as encapsulant into a plastic leaded chip carrier (PLCC) consisting aInGaN light emitting diode in the PLCC cavity. The light emitting diodes was determined to have electroluminescent emission at 450 nm wavelength range.
The InGaN containing PLCC package with nano particles containing encapsulant material was connected to a DC voltage power source with forward voltage of 3.2V and current of 350 mA. In some embodiments the LED has a higher or lower current, for example 450 mA LEDs are now being implemented in one other alternative design by the applicant. The device optical emission spectrum was characterized to result in two emission peaks one at 450 nm wavelength range and the second at the 660 nm wavelength range. The 660 nm wavelength range emission peak's full width at half maximum was observed to be over approximately 60 nm. The intensity ratios of the 450 nm and 660 nm peaks were 0.5:1. The aforementioned experiment has been conducted by the applicant. It is in accordance with the invention to produce several quantum dots as described above, some of different sizes. These quantum dots, one or many quantum dots may be driven with electric current/voltage from a power source or the said one or many quantum dots may be driven by optical excitation or both optical excitation and electric current/voltage from a power source in accordance with the invention.
It should also further be noted that the embodiment 31 can be readily permuted and/or combined with any of the embodiments 20, 30, 32, 40, 50, 60, 70, 71 and/or 80 in accordance with the invention.
Furthermore any light emitter design from EP11158648.3, of the inventor and applicant can be combined with embodiment 31. This document is cited here as reference.
It should also further be noted that the embodiment 32 can be readily permuted and/or combined with any of the embodiments 20, 30, 31, 40, 50, 60, 70, 71 and/or 80 in accordance with the invention.
Furthermore any light emitter design from EP11158693.9, of the inventor and applicant can be combined with embodiment 32. This document is cited here as reference.
It should be noted that any of the embodiments 30, 31, 32 may be used to produce a broad UV component in some embodiments of the invention.
The spectral features 401, 402, 403 in thick black are designed to illuminate the flowers in the plants to insects, making them maximally observable to insects. These features are typically produced by a LED and/or a quantum dot powered by electric current. In some embodiments filters, such as band-pass filters can be used with LEDs and/or quantum dots to produce the spectral features 401, 402, 403.
At least one spectral feature 401, 402, 403 should have a relative intensity level sufficient to highlight the flower from the background. In one preferred embodiment the relative intensity level is such that the intensity is doubled by the spectral features 401, 402, 403 in the respective bands of the spectral features. In another preferred embodiment, the relative intensity level is such that the intensity is increased to ten times higher or more by the spectral features 401, 402, 403 in the respective bands of the spectral features, thus providing logarithmic amplification.
It should also further be noted that the embodiment 40 can be readily permuted and/or combined with any of the embodiments 20, 30, 31, 32, 50, 60, 70, 71 and/or 80 in accordance with the invention.
It should also further be noted that the embodiment 50 can be readily permuted and/or combined with any of the embodiments 20, 30, 31, 32, 40, 60, 70, 71 and/or 80 in accordance with the invention.
It should also further be noted that the embodiment 60 can be readily permuted and/or combined with any of the embodiments 20, 30, 31, 32, 40, 50, 70 and/or 80 in accordance with the invention.
It should also further be noted that the embodiment 70 can be readily permuted and/or combined with any of the embodiments 20, 30, 31, 32, 40, 50, 60, 71 and/or 80 in accordance with the invention.
In embodiment 71 the plants are arranged in shelves in open and closed growth chambers to save space. Naturally the inventive lighting device can be used to illuminate all or some plants collectively, as the lighting device 720 attached to the roof, or small lighting devices of the invention can be attached on the shelves, or in growth chambers, to illuminate plants to the insects more locally.
It should also further be noted that the embodiment 71 can be readily permuted and/or combined with any of the embodiments 20, 30, 31, 32, 40, 50, 60, 70 and/or 80 in accordance with the invention.
It should also further be noted that the embodiment 80 can be readily permuted and/or combined with any of the embodiments 20, 30, 31, 32, 40, 50, 60, 70 and/or 71 in accordance with the invention.
In some embodiments of the invention one or more spectral peaks are arranged to be emitted in the 340-440 nm band. It should be noted that in any of the aforementioned embodiments it is also in accordance with the invention to provide a broad UV spectrum, providing broader usability, as the reflectivity of the light on the various surfaces is better in general. The broader UV component may be used to replace one, more or all spectral peaks or complement them in accordance with the invention. Using a quantum dot LED it is possible to produce a broad electroluminescence spectrum at UV wavelengths. In all of the aforementioned embodiments it is possible to provide for a feature where the photosynthetic illumination spectral component and the pollination enhancing spectral component are controlled separately, i.e. one, the other or both may be on or off as needed. It is also in accordance with the invention to provide means for adjusting the relative emission intensities of the said two components.
The invention has been explained above with reference to the aforementioned embodiments and several commercial and industrial advantages have been demonstrated. The methods and arrangements of the invention allow lower insect mortality as the LED and/or quantum dot based design is harmless to the pollinating insects. Prior art light devices relying on electric discharge typically attracted insects, but also heated to extreme temperatures, killing many pollinating insects that were drawn close to the prior art light device. A further advantage of the invention is that as the insects see the flowers better, pollination efficiency is increased, leading to more enhanced reproduction by the plants and an increase in crop.
The better survival rate and improved vision have a synergistic added advantage: the insects are known to be capable of learning to operate in different illumination conditions and wavelengths. However, if the insects are killed by hot lamps very early on, no learning will have taken place. A light device that is not lethal to insects also adds to improved pollination by its effect of allowing more educated insects to pollinate the plants more effectively than ever before. The light device provides also for better rested insects as the insects find to their nest easier with the inventive light solution than without it. As the insects are capable of learning, it is possible that the insects can work quite effectively in illumination conditions where the peak wavelength of the illumination is not at maximum sensitivity, when they are provided with the chance to adjust to the lighting conditions.
LEDs of the invention provide also an improvement to current solution using HPS and HID due to their capability of easy spectrum in-situ tuning, e.g. UV LEDs can only be turned on during a pollination event, i.e. when pollinating insects are present near the plants. When turned off UV light does not assist harmful insects, such as pests, to find plants. This is not possible in HPS and HID lamps of the prior art. Producing UV light also consumes more energy and therefore it is beneficial to have that spectrum component off when not being used.
An even further advantage of the invention is that the light device of the invention enhances any or all of the following: fruit production, plant reproduction and/or plant growth. This enhancement has a synergistic improvement in crop levels that goes beyond the levels that could be achieved by using either one illumination solution individually or separately, and it goes beyond the sum of the individual effects. More green plant growth provides the basis for bigger and higher quality fruit, the better developed fruit increases the prospects of success for the next greenhouse plant generation, more plant reproduction produces more fruit, which more fruit is better supported by the photosynthetically stronger plant growth. It is with these synergistic improvements that the invention alleviates the global problem of hunger.
The invention has been explained above with reference to the aforementioned embodiments. However, it is clear that the invention is not only restricted to these embodiments, but comprises all possible embodiments within the spirit and scope of the inventive thought and the following patent claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 11169473.3 | Jun 2011 | EP | regional |
| Number | Date | Country | |
|---|---|---|---|
| 61507677 | Jul 2011 | US |
