Growing Plants with LED's
Circles of Life Growing Plants Technology - Crop Production Systems How Light Colour Influences Plant Growth LED Lighting Technologies to Substitute Natural Light Pros and Contras LED Grow Light Systems My-tronic GmbH to Produce LED Grow Light Systems on Request
(PRWEB) April 4, 2005 -- In some dictionaries life is defined, as a power
that demonstrates a purpose to feed, process matter into energy, grow, and
reproduce. Life means existence, a state of being. No matter how we look at the
definitions, one thing is clear: life is the energy driving the universe and all
its happenings, and for humans and all the living organisms, life, or being
alive, is a force entirely dependent on special factors such as air, water,
light and much more elements that interact to support existence in all its forms
and each of them is equally important for the survival of the
species...
All these resources are an abundant presence on Earth, but
nothing can last forever. Polluted water is not usable, air is itself
contaminated on many parts of the Globe, mineral resources are non-renewable and
light… natural light has its benefits but also it can constitute a danger for
the species if we consider the UV emissions reaching Earth’s
atmosphere.
Light influences all life on Earth directly or indirectly.
Plants need light for photosynthesis, therefore for growing and in exchange they
forward their energy to the animals that consume them. At the same time animals
need light for a harmonious evolution and even nocturnal ones require some low
level illumination. Lack of natural light causes various disorders by people and
the same happens by plants and animals.
UV light can harm living
organisms in several ways. For example plants overexposed to UV light reduce
size and are more susceptible to specific diseases. The light coming direct from
the sun sends to earth three types of ultraviolet: UV-A (380-315 nm), UV-B
(315-280 nm) and UV-C (280-10 nm). Due to the absorption in the atmosphere's
ozone layer, 99% of the ultraviolet light that reaches the Earth's surface is
UV-A.
While UV-A causes plants only a little harm, UV-B, which is a
shorter wavelength, can damage plant tissue and in humans it can cause skin
cancer. UV-C is the part from the UV spectrum with the shortest wavelength and
all bacteria and virus get deadly sunburn in an artificial UV-C filter system.
Certainly UV light has its paradoxes: even if it is harmful in one way, it is
useful in another. Medicine is using this artificial UV light to cure difficult
skin conditions such as psoriasis eczema, lymphoma, acne, a-topic dermatitis,
and so on.
Fact is that plants don’t need too much UV light, on the
contrary. This is why crop production with artificial light means that will
eliminate the dangerous UV emissions seems to be the next logical
step.
Growing Plants Technology - Crop Production Systems
The
target of crop production systems is to develop innovative technologies that
lower the costs of harvest and ensure ecologically aware crop farming.
The crop production systems do not disregard important factors that
influence plant development: temperature, humidity, light, carbon dioxide, water
and nutrients. All these blend to create the ideal environment for a plant to
grow and reproduce as well as they influence size, seeds, plant health and so
on. Each plant will progress in its own manner, depending on the environment.
Since a long time already biologists are studying the factors that influence
vegetation’s evolution. Light is a very important factor and researchers were
able to determine exactly which wavelengths are the ones plants need for their
growth. Some colours in light rays are essential for good plant evolution.
Vegetation mirror and receive a small amount of energy from yellow and green
emissions of the visible spectrum. However the red and blue fractions of the
light continuum are the most valuable energy resources for plant life, and
plants necessitate more red (625 to 675 nm) than blue (400 to 470nm). Yellow
(525 nm) triggers photosynthesis too, while IR influences seed spurring and UV
colour and scent.
How Light Colour Influences Plant Growth
Blue
light: plants react to the intensity of blue light. Lessening the blue light
will cause poor growth – the strength of the radiation in any other part of the
spectrum is not as important as the intensity of the blue, which shapes height
and quality.
Red (660 nm) and infrared (730 nm) (also known as IR or far
red) light: Intensifying the total of IR in relation with 660 nm red makes
plants grow tall and thin. On the other hand if red is increased while IR
diminished, plants will be short but thick. Plant reactions are not linear with
the red/far red ratio and they can also vary in their response to red and far
red light.
Ultraviolet light (UV): While overexposure is dangerous, small
amounts of UV light can be beneficial for the flora. In many cases UV light is a
very important cause for colours, taste and aroma. But UV-C and UV-B are
believed to stop plant spread and this is why they have to be removed from the
light under which plants are developed in green houses by UV stabilisers or
glass. Removal of the UV up to 400nm is might be effective also in case of virus
carrier insects (as insects see partly in UV).
Direct light from the Sun
distributes the useful wavelengths only on special times of the day and in small
quantum enough for a harmonious growth in some parts of the Earth, yet not
enough on others.
Crop production systems are dealing with such problems
and find ways to replace natural light with artificial light. The idea of
growing plants under artificial illuminators is not new at all. Long time ago
NASA started to grow plants in space, and the results were astonishing. Nowadays
we know that by using the correct wavelength plants develop harmonious and
healthy, sure if they have all the other conditions ensured. Yet getting light
of the correct wavelength is not an easy task, especially if one takes into
account the costs and efficiency of such light sources.
LED Lighting
Technologies to Substitute Natural Light
To substitute natural light is
quite difficult also if you consider how hard it is to obtain light near the
visible part of the spectrum with traditional luminaries. Light emitting diodes
are here to change that difficulty.
SSL (solid state lighting) is the
youngest lighting technology and by now is believed to be more efficient than
incandescence and fluorescence due to the fact that SSLs produce light at or
near the visible part of the spectrum and as a result the emitted light can be
used straight or with minor conversion. One of the most important advantages is
that SSL technology has eliminated damaging components from the light sources
(remember: light emitting diodes contain no ultraviolet unless they are produced
as UV LEDs).
NASA is already using SSL in its space farming systems. The
reasons are quite simple: incandescent or fluorescent lamps are not efficient
enough for such purposes, because they consume a lot of electrical power,
generate heat and contain electrodes that burn out (maintenance costs are high).
This is why NASA’s plant physiologists started to work with light emitting
diodes (blue and red) to grow salad plants such as lettuce and radishes. The
researchers found our that blue and red light is essential for plant growth and,
in general, a percentage of 8% blue LEDs and 92% red LEDs, both with the same
frequency and relative intensity per LED, are enough for a harmonious evolution.
Blue has a smaller influence than red; however a percentage between 1% and 20%
of blue light can be selected, depending on the plants and their growth
requirements. The NASA scientists have tried to create the most cost and energy
efficient light sources possible, and this is why they have eliminated from the
fixtures other colours normally found in white light. "What we've found
basically is that we are able to limit the amount of colour we give to the
plants and still have them grow as well as with white light." said the research
scientist Greg Goins of Dynamac Corp. LEDs are not the only ones efficient for
growing plants: sulphur microwave lamps are the most efficient light sources
known to man, that can generate as much light as the noonday sun, perfect for
illuminating large-scale systems such as greenhouses. For smaller applications,
such as indoor gardens, LEDs seem to be the right choice.
Pros and
Contras LED Grow Light Systems
There are some pro and contras when it
comes to LED grow light systems. When planning such farming alternatives, one
has to carefully consider that plants do use light at all wavelengths from UV to
IR, as explained above, needed to convert water and carbon dioxide into sugars.
Some plants use more red and blue, less green and yellow, while others use green
as much as they use red and blue, as well as the light in between. If LEDs are
chosen for brightness, there is one aspect to be underlined: they just look
bright because their light is unidirectional and their size is small. To get
enough light there are many LEDs needed, that’s why the cost of LED arrays or
LED modules is so high. LEDs can be calibrated to emit only the light most
efficient for the plants, but not all the light plants need. This is why such
light sources are recommended only in places where direct light from the sun is
not enough or inexistent – space farming for example. Also in places where light
from the sun is too strong and can harm the plants with the high emission of UV,
LEDs are a good choice, because UV filters are stopping some of the useful
wavelengths too. In wintertime the weather conditions restrain crop production;
this is why greenhouses need a substitute for the natural light. It makes sense
to deliver plants the minimum lighting conditions for a corresponding
evolution.
There are some significant factors to take into account when
choosing light sources for such applications and these are low costs, energy
efficiency, long life, and ability to withstand voltage fluctuations, modularity
in order to grant users the possibility to assemble arrays that gives as much
light as needed, where needed. LEDs are pretty efficient in the conversion of
electric power to light, in any case more than traditional fluorescent and
incandescent lamps. Due to the fact that light emitting diodes can be
manufactured to emit a specific wavelength and are expected to have a long life
span (from 50000 hours up), many plant physiologists are considering using them
in large applications. Compared to LEDs most of the other traditional lamps have
to be replaced every two-three years. Other features such as choice of viewing
angles, control options, instant turn on times, cold start and much more,
recommend the semiconductor devices. At present this is still an expensive
technology, but in time LEDs efficiency will be maximized while prices reduced
and these details are a good base for future planning.
My-tronic GmbH to
Produce LED Grow Light Systems on Request
It is so far clear that in
order to produce efficient LED grow light systems a lot of investigation is
necessary. It is not enough to mount some blue and red LEDs on a PCB and say:
“that’s it; we’ve got the plant growing LED system”. NASA created only a
mechanism that delivers the minimum amount of light needed for some plants. For
greenhouses on Earth other questions need to be answered: how much blue, how
much red? What about the other colours, what about UV and IR? Should the light
pulse? Should it be dimmed in the morning and evening to imitate natural
conditions (sunrise and sunset?). Do plants need light at night? And the list
remains opened.
At my-tronic GmbH there are no plant physiologists, but
only engineers ready to bring their technical expertise to scientists in order
to build the best light sources for LED plant growth systems. The domain is
still new and can be considered a challenge for any researcher. Still
my-tronic’s engineers know exactly which are the LEDs’ limitations, what can be
done with such devices and what not. And the company’s motto: “bringing light in
your lives” is also a statement of commitment to life and
development.
Mihaela Lica for my-tronic GmbH
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