types of lamps for artificial lighting of plants

Discharge lamps

High pressure discharge lamps. Very effective (more than 30% of the used power is converted into light, while the luminescent efficiency is about 15%), but it gets very hot and requires the installation of a cooling system, such as a fan. More often used in greenhouses and winter gardens, rather than for the illumination of apartment plants.

Fluorescent lamps.

They provide uniform illumination of the required surface and do not heat up significantly during operation (up to approximately 40-45 ° C), which allows these sources to be located in close proximity to plants, up to a distance of about 10 cm. From domestic products they are used as ordinary white light lamps ( LB), as well as special fitolamps (LF) and lamps of natural color (LEC). Phytolamps have the most appropriate emission spectrum with two maxima - in the blue and red regions (due to more complex selection of phosphors). Of the most popular imported fitolamps of German companies OSRAM and SYLVANIA: Sylvania Gro-Lux, Osram Fluora (in the model range there are lamps with a capacity from 15 to 58 W, their cost is $ 3.5-5). Fluorescent phytolamps manufactured by PHILIPS, DULUX and GENERAL ELECTRIC are also used. The lamp may include one or more lamps (they are in the form of tubes) and ideally supplied with a reflector. The Philips Reflex Super / 80 NG model is equipped with an internal reflector, which significantly increases the light output of the lamp. It is not recommended to use specialized aquarium lamps for plant illumination; they have a slightly different emission spectrum. Although many models are universal and are used both in aquariums and for plant lighting. The lamp can be mounted on the ceiling (preferably on an adjustable suspension), on walls or on special tripods. It should not interfere with the flow of natural light and interfere with the care of the plant.

Conventional incandescent bulbs

Conventional incandescent lamps for plant lighting are used quite rarely, because in their spectrum there is no blue-violet component. Although there are incandescent bulbs with an enhanced blue component of the spectrum - they have special coatings on the glass (for example, the Osram Concentra Spot Natura reflector lamp with a power of 60 and 100 W, cost about $ 7).

In order not to disturb the natural biorhythm of plants, artificial lighting should be used regularly. The length of daylight hours is approximately the same for all species and is 12-16 hours. How to determine the power of the lamps, which are able to provide the necessary illumination for these plants? Of course, it all depends on whether these fluorescent lamps or gas-discharge lamps, on the demands of the cultivated crops, as well as on the distance between the light source and the plants. When selecting lighting devices, the following calculation is used: the amount of photosynthetically active radiation should be 50-70 W / m2 for shade-tolerant and 120-200 W / m2 for light-loving species. If you have the opportunity, contact the specialists - they will calculate the necessary power for you, using special computer programs.

Illumination is often used not only with a purely practical purpose, but also to create all sorts of artistic effects: emphasize the texture of the leaves, make a more voluminous plant shape, "play" shadows on the walls and ceiling.

LED lighting is one of the promising areas of artificial lighting technology [1], based on the use of LEDs as a light source.

The development of LED lighting is directly related to advances in white LED technology. Developed so-called super-bright LEDs, specifically designed for artificial lighting.

Benefits

Compared with conventional incandescent lamps and fluorescent lamps, LED light sources have many advantages:

1. Economical use of energy compared with previous generations of electric light sources - arc, filament and gas-discharge lamps. Thus, the light output of LED street lighting systems with a resonant power source reaches 120 lumen watts, which is comparable to the impact of fluorescent lamps - 60-100 lumens per watt. For comparison, the light efficiency of incandescent lamps, including halogen ones, is 10-24 lumens per watt.
2. With optimal power supply circuitry, the use of high-quality components and ensuring proper thermal conditions, the service life of LED lighting systems while maintaining acceptable indicators for general lighting can reach 36–72 thousand hours [2], which is on average 50 times longer than the nominal service life incandescent bulbs of general purpose [3] and 4–16 times more than most fluorescent lamps. Due to continuous updating and improvement of products, manufacturers of LEDs do not have the ability to conduct testing in real time and indicate the predicted service life using special techniques, such as TM-21 and IESNA LM-80 [4]. Long service life in some applications plays a decisive role. Thus, the savings on maintenance and replacement of lamps in street lamps often exceed the savings on electricity [5].
3. The ability to obtain different spectral characteristics without the use of filters (as in the case of incandescent lamps).
4. Directional radiation without the use of a reflector, the possibility of changing the radiation angle with the help of lenses (lenses for incandescent lamps with a comparable luminous flux have larger dimensions and cost).
5. The lack of inertia when switching on and off, which is important for light-dynamic installations.
6. Dimmable compared to most types of fluorescent lamps.
7. Safety use.
8. Small size and, as a result, smaller, compared with a fluorescent lamp, the amount of phosphor containing rare earth materials. [6]
9. High strength.
10. The absence of mercury compounds in the composition (as opposed to gas-discharge fluorescent lamps and other devices), which excludes mercury poisoning during processing and during operation.
11. The almost complete absence of ultraviolet and infrared radiation.
12. Low temperature (for low-power devices).
13. Resistance to vandalism.

disadvantages

1. High demands on the quality of the heat sink, since temperature has a decisive influence on reliability [7]. Powerful light-emitting diodes require an external radiator for cooling, because they have an unfavorable ratio of their size to the heat output and cannot dissipate as much heat as they emit without a special heat sink. Thus, to dissipate 5 W of thermal power emitted by a semiconductor device with the ability to work at ambient temperatures of up to +40 ° C, a radiator with an area of ​​100 cm2 will be required [8]. The need to use a radiator increases the cost of the finished product and complicates the design of LED lamps over 15 W, compatible with the size of the basement and the dimensions of incandescent lamps for general purposes.
2. Impossibility to work at high (more than +100 ° C) ambient temperatures (saunas, ovens, microwave ovens, etc.)
3. The power supply of the LED is significantly less than the supply voltage of ordinary incandescent lamps. To power a single LED from the network, a DC power converter is required, which additionally increases the luminaire volume, and its presence further reduces the overall reliability and requires additional protection.
4. The successive switching on of several LEDs in some luminaire schemes reduces the overall reliability of the device, since the failure of one LED leads to the disconnection of the entire chain.
5. Relatively high price. However, at the beginning of 2011, LED lamps were already on sale at prices (per lumen), competitive with compact fluorescent lamps.
6. Cheap mass LEDs have a light return of 80–110 lm / W, which is lower in efficiency than modern sodium lamps [9]. In this connection, despite the active introduction of low-cost LED lamps in various industrial and municipal consumer services, currently for lighting streets and courtyards, one of the most energy-efficient and reliable light sources are DNaT lamps (Light output of high-pressure sodium lamps reaches 150 lumen / watt, low pressure - up to 200 lumen / watt).
7. The spectrum of the LED lamp is different from the solar one, so you have to compromise between the light power and quality. However, it is often, with properly selected phosphors, better than fluorescent lamps [ source not specified 468 days ].
8. Despite the ease of adjusting the brightness of the LED by varying the constant voltage supplying it, most LED lamps designed for mains voltage do not work through a dimmer for incandescent lamps. The reason is the design of the built-in lamp of the secondary power source. However, there are dimmable LED lamps that can be plugged in with a dimmer for incandescent lamps. The cost of such lamps is usually more expensive by 10-30%, and the brightness during rotation of the dimmer regulator is regulated in steps from 20% to nominal. Such a lack of dimmers, specifically designed to control the corresponding LED lamps.
9. Cheap lamps connected to the 220 V network flicker (pulsation of the luminous flux) with a frequency of 100 Hz, which can adversely affect vision.
10. The blue component of the spectrum used in LED lighting has a negative effect on the functioning of the food chains of the fauna and attracts invertebrates from the countryside to the cities. [10]

Application

LED lighting technology due to efficient energy consumption and simplicity of design are widely used in lamps, spotlights, LED strips, decorative lighting, and especially in compact lighting devices - hand torches. Their light power reaches 5000 lm. LED lighting devices are divided into street and interior. Today they are used to illuminate buildings, cars, streets and advertising structures, fountains, tunnels and bridges. This lighting is used to illuminate the production and office space, home interior and furniture.

LED lighting is used in lighting to create design lighting in special modern design projects. The reliability of LED light sources allows them to be used in places that are difficult of access for frequent replacement (built-in ceiling lighting, inside stretch ceilings, etc.).

Decorative LED lights are mainly used for festive illumination. Used as a Christmas decoration - LED garland. During the holidays (mostly New Year's) they can be seen on the streets of the cities, they decorate trees, facades of buildings and other street objects.

The advantages of LED lighting for plants

• In contrast to sodium lamps, LEDs consume almost 5 times less electricity, for example, a LED lamp for plants that consumes 90 watts corresponds in efficiency to 270 watts DNA, DNAT;
• They do not heat up (sodium lamps are heated from 200 to 600 degrees Celsius) and have a more complete spectrum of light;
• Provide continuous complex and long-term additional illumination of plants - up to 50,000 hours;
• Able to work in the control mode of the process light process (adjusting the intensity and spectrum of radiation);
• Savings - zero maintenance costs;
• Saving on additional equipment - often does not require additional cooling and a reflector;
• They are mainly modular;
• They are characterized by mobility, placed on a light suspension;
• Quickly mounted by functionally independent modules;
• They have compact weight and size parameters with a relatively high performance;
• Do not require constant monitoring of the mode of illumination;
• Do not require preliminary engineering preparation of the area for placement.
• Have a high luminous efficiency of LEDs;
• They have high energy efficiency (the efficiency of the LED lamp is 96%, that is, almost all of the electric power turns into light, as opposed to 30% of the DNAT lamps)
• It is harmless to humans and the environment - does not contain mercury and other hazardous substances, there is no ultraviolet and infrared radiation;
• Energy efficiency and environmental friendliness.

The use of LED lighting for plants:

1. For greenhouses, winter gardens, oraznerey, as well as to replace obsolete lamps such as DNA and DNAT. At the same time, for additional effective illumination of plants on an area up to 2 sq. M, with a suspension height of 1.8-2.5 m, together with natural light in the autumn-winter-spring period, as well as for additional effective illumination of plants on an area of ​​up to 6 sq. . m, with a suspension height of 2.5 m to increase the yield and growth rate in the summer.
2. For the closed rooms, storerooms, rooms, bulk boxes, etc.
3. The main illumination of the area is up to 1.1 m2, with a suspension height of 0.4-1.3 m.

Signals that indicate a lack of lighting for plants:

• Plant growth slows down.
• The distance between newly formed leaves and shoots increases, the stem becomes thinner.
• The newly formed leaves are somewhat smaller in size.
• Lower leaves turn yellow and fall off.
• Flowering plants form few buds, and at the same time they are paler than usual; buds do not develop and fall off.
• The motley leaves turn green.

Signals indicating excess lighting for plants:

• Although the ground is wet enough, the leaves are drooping by day.
• The leaves, on which the direct rays of the sun fall, turn yellow - first along the edges, and then completely.
• In the worst case, when the leaves - partially or completely o become brown and dry, you can even talk about "sunburn".

Creating artificial lighting

Plant foods used for growth and mass creation are simple organic compounds - hydrocarbons. Plants themselves produce them from carbon dioxide and water as a result of the photosynthesis process. This process is carried out through the use of light energy absorbed through the so-called assimilation pigment - chlorophyll, contained mainly in the leaves. The product of plant photosynthesis is also oxygen released into the atmosphere, which is necessary for the life of other organisms.

The intensity of photosynthesis depends on the intensity of light, the content of carbon dioxide and the supply of water, as well as on the surrounding temperature. What is important, however, is not only the total amount of light energy reaching the plant, but also the spectral composition of the light, as well as the mutual correlation of the periods of illumination and the absence of light, or day and night - the so-called photoperiodism.

Now, what is sunlight? This is a range of individual colors. Photoculture of plants consists of such factors: the spectrum of light (certain wavelengths), the amount of light (suites, lumens, watts and so on, take into account the distance from the luminaires here), time interval (duration of exposure), frequency of exposure (frequency), thermal regime (certain frequency of light). During the day, these factors develop in such a way that the plants receive the necessary portion of light to grow. In nature, these factors are combined quite rarely (in a small period of the year), otherwise, we would get a large number of harvests. Is it possible to get more crops in the same time period of cultivation? It turns out this is possible in the environment of artificial lighting with the help of diode assemblies (LED lamps, spotlights, arrays, lamps).

In the process of photosynthesis of plants, electromagnetic radiation is used, the wavelength of which is 400-700 nm. Light in this range is able to stimulate plant growth. This is the so-called PAR-range (short for Photosynthetic Active Radiation-photosynthetic active radiation). About 45% of solar radiation is in the PAR range. Thus, if a lamp is designed to stimulate plant growth, the bulk of its spectrum should be in this range. And the spectral range of light waves used by plants is called photosynthetically active radiation (PAR or PPF (photon flux density)).

Parameters of wavelengths of LED lighting for plants:

• 370-380 nm UV
• 410-420 nm Violet
• 450-460 nm Royal blue
• 460-475 nm blue
• 520-530 nm Green
• 585-595 nm Yellow
• 605-618 nm Orange
• 620-635 nm Red
• 650-660 nm Far red
• 720-730 nm IR
• 850 nm IR
• 940 nm IR

White:

• 2500-4500 K Warm White
• 5000-7000 K White
• 7500-20000 K Cool White

The photosynthetically active radiation index is the only measure for assessing the suitability of a light source during photosynthesis. Чем выше такой показатель на ватт электрической мощности источника света, тем более он эффективен для роста растений. Показатель фотосинтетически активного излучения выражается в микромолях на секунду (µмоль/с). Скорость роста и развития растений зависит, прежде всего, от интенсивности облучения, то есть излучаемой энергии, выпадающей на единицу поверхности, а значит от мощности и количества установленных тепличных светильников.

Ультрафиолетовое излучение ниже 380 нм и инфракрасное – выше 780 нм в фотосинтезе не используется, но влияет на так называемые фотоморфогенетические процессы растений, связанные помимо прочего с ростом побегов, разрастанием, окраской листьев, цветением и старением растений.

В большинстве случаев мы оцениваем интенсивность освещения для растений в соответствии с особенностями глаза – человеческого органа зрения. При этом человеческий глаз видит только часть лучей, из которых состоит солнечный свет. Этот свет раскладывается на различные цвета спектра. Мы можем наблюдать это на примере радуги, где благодаря преломлению света представлены семь цветов спектра. Люди с хорошим зрением различат в ней фиолетовый, синий, голубой, зеленый, желтый, оранжевый и красный. Не все цвета солнечного спектра одинаково важны для растений: все равно, растут ли они в комнате или на улице. Для процесса фотосинтеза прежде всего необходимы синий и красный цвета. Это стоит учитывать, устраивая искусственное освещение для растений. Если Вы, например, повесите над ними обычную лампу накаливания, то, на первый взгляд, растения будут достаточно освещены. В действительности же лампа накаливания преобразует в свет только 5 процентов получаемой электроэнергии, остальная же ее часть теряется в виде тепла. Спектр излучения этой лампы составляет, в основном, красный цвет. Поскольку синий цвет отсутствует, рост растений замедляется, а их стебли становятся тоньше. Итак, для освещения растений следует использовать лампы, в спектре излучения которых присутствуют как синий, так и красный цвет, потому как уже было сказано выше — большая часть фотобиологических процессов в растениях наиболее интенсивно протекает при облучении излучением в сине-фиолетовой и оранжево-красной области спектра. Для глаза свет этих ламп кажется несколько непривычным.

You are likely to ask why for LED light sources for plant lighting do not indicate luminous intensity? Lumen is a unit of measure suitable for standard lighting. The plants have other requests. The power of PAR sources is measured in watts per square meter, but in any case it is difficult to determine the value accurately.

Type of plant lighting:

• constant backlight;
• photoperiod lighting;
• cyclic;
• short-term highlighting at specific time intervals.

Consider the example of ripening under LED lighting fitolampy cucumbers and tomatoes:

In the lamp for plants (phytolamp), LEDs with spectral characteristics are used for the best absorption of light by plants. The following wavelengths are used in these LEDs.

Light can be considered as the energy of electromagnetic oscillations with a specific wavelength. The unit of measurement of wavelength is a nanometer (millimicron). The spectrum of all solar energy can be divided into three main parts:

• ultraviolet rays (10-400 nm);
• visible radiation (400-760 nm);
• infrared radiation (more than 760 nm).

According to the physiological effect on plants, certain parts of the spectrum differ in the following way.

1. 1. Rays with a wavelength of 280 nm - kill the plant.

1. 1. Rays with a wavelength of 280-315 nm are destructive for most plants.

1. 1. Rays with a wavelength of 315-400 nm - the plant becomes shorter and the leaves are thicker.

1. 1. Rays with a wavelength of 400-510 nm - the second maximum absorption by chlorophyll.

1. 1. Rays with a wavelength of 510-610 nm - the zone of the spectrum of weakened photosynthesis.

1. 1. Rays with a wavelength of 610-700 nm - the zone of maximum absorption by chlorophyll and maximum photosynthetic activity.

1. Rays with a wavelength of 700-1000 nm - little studied.

The wavelength of ultraviolet rays reaching the ground, in which the plant feels the need, varies from 280-400 nm.

From the above, we see that LEDs (LEDs, Light Emitting Diodes) are ideal in lighting for plants, because they allow you to get light waves of strictly defined values. In addition, they have a fantastic lifespan (up to 100,000 hours), and this makes them the most suitable light sources for greenhouses and greenhouses. The price of LEDs for plants is gradually decreasing and they are becoming more and more accessible to us. LED lamps consume 75% less energy compared to traditional light sources, which makes it possible to recoup them in just a year. And given their longevity - and faster. Of these modern fixtures, you can arrange the most intricate design of the backlight - you do not need to disassemble it every time the lamp burns out. And the last - a distinctive feature of LEDs for plants is the absence of ultraviolet and infrared radiation, so these LED lamps are absolutely safe for any plants and for the environment.