Horticultural research has determined that some of the relatively narrow spectral band radiation can promote chlorophyll uptake in plants, thus promoting the process of photosynthesis. Packaged led manufacturers and solid-state lighting (SSL) finished manufacturers are moving to get a slice of the fast-growing market. At the same time, researchers continue to work out how other wavelengths can further improve the productivity of greenhouse and indoor commercial farms.
The combination of LED lighting and commercial growers of flowers and vegetables is natural. Whether it is in a greenhouse that needs to be filled, or in an indoor environment that relies entirely on artificial light, the cost of gardening lighting is a major expense for farms. Energy-efficient solid-state lighting (SSL) products have pledged to reduce electricity tariffs from the outset.
However, research on "How specific spectral bands affect the different stages of plant growth cycles" makes LEDs more suitable for this application. Broad-spectrum light sources, such as metal halide lamps, essentially waste energy in the radiation that produces some of the spectral bands, such as green light, which is now proving to have no benefit at least for plant growth. In contrast, the monochrome nature of LEDs means that solid-state lighting manufacturers can produce lamps that emit only the spectral energy needed by a plant, thereby increasing energy efficiency.
In fact, lighting-centric gardening is far from enough, but some principles have been established, and researchers have continued to study the relationship between specific spectral bands and vegetable or floral production. and led manufacturers are studying this. For example, Osram Optoelectronics Semiconductor company released the so-called "far Red led", center wavelength 730nm
Figure 1. Osram New 730nm LEDs can increase the productivity of peppers, tomatoes and roses.
Osram Solid State Lighting application manager Kim Peiler said the 450nm and 660nm bands as the peaks of chlorophyll uptake for all plants were fully confirmed. However, new research has shown that the combination of 660 and 730nm light can affect photosensitive pigments in plants. Peiler adds that stimulating plant pigments can make plants bloom faster.
Researchers are also studying how to apply far red light and what they do in the plant's growth cycle. For example, Peiler says that depriving plants of red light can simulate shadows and cause plants to grow longer stems that can be used for grafting. But in another phase of the growth cycle or in different applications, red combinations may trigger flowering quickly.
The combination of LED types will continue to develop in horticulture. Osram also offers orange, yellow and green monochrome LEDs as well as researchers are experimenting with phosphor-converted white LEDs. Why is it a white led? The blue light Pump in the white LED provides the desired blue peak, while the workers in the gardening environment need white light. Therefore, the red and white LEDs are used to prove that it is useful to provide the light that plants and humans need.
Gardening Lighting Products
At the same time, horticultural solid-state lighting market potential is driving new lighting manufacturers into the market segment. For example, Hubbell Lighting introduced the nutriled horticultural lighting product line using $number NM red LED and $number NM blue LED (Figure 2). Hubbell New Product Innovation manager Tom Veltri said that Blu-ray LED is the key to vegetative growth stage, and red LED can promote flowering and result. Hubbell is using a 2:1 red-blue blend, and Veltri says it can serve the widest segment of the horticultural market.
Figure 2. Hubbell introduces a scalable nutriled luminaire that can be connected in parallel to form a linear luminaire.
Ask Veltri why Hubbell as a mainstream lighting manufacturer decided to enter the small market for horticulture? Veltri says market potential is driving this decision. He pointed out that Hubbell's survey showed that "many farmers have a canopy of 1 million to 2 million square feet."
In addition to the previously mentioned market potential for improving plant productivity and energy conservation, Veltri also mentions trends in "from farm to table" and organic food, driving indoor farms. "Indoors, you can control the environment more effectively," he said. The premise of "from Farm to table" essentially requires growers to operate near areas of population concentration.
Veltri also discussed the relationship between minimizing distance between farms and consumers and crop yields. He said production would be lost in harvest, transportation and shelf life. Reduced delivery time and distance can reduce the loss of production and extend the shelf life.
Finally, indoor farms can be kept in operation and can be produced only with a small fraction of the traditional farm area. With LED lighting, farms can be layered into plants, such as lettuce, or 20-foot-tall tomatoes. This tomato crop can be embedded in a way that will bring the LED light up vertically, along the direction of plant growth. It's like putting an LED near a lettuce or tomato leaf, and it doesn't burn plants.
Of course, compared with general lighting, gardening does require a number of different lighting design principles. The nutriled horticultural lighting products designed by Hubbell are extensible. This type of line light has 2 and 4 feet, which can be combined in parallel (Fig 3) and end-to-end connected. Each luminaire has a complete drive, and the Hubbell provides a short power cord that can be daisy-chained to connect up to 16 lamps to an AC power source.
Figure 3. The nutriled luminaire includes a built-in parabolic reflector which provides a 60° beam pattern.
Veltri also explained that Hubbell designed this optical system to provide 60 ° linear beams-more compact than the typical high-power led Lambert model. The luminaire design includes a parabolic reflector, an acrylic lens for protecting the LED on the inside of the stamping and anode anodized aluminum lamp. In addition, the design allows the luminaire to be placed in a row of plants, not only to illuminate the top of the plant, but also to provide vertical illumination to a lower position.
Greenhouse and professional applications
Of course, the application of LED in horticulture is not only indoors. Many greenhouses need additional illumination. For example, Lumigrow, a horticultural lighting manufacturer, recently published a case study with Patterson greenhouses of the North Carolina State Broadway town. Patterson is using Lumigrow lamps to extend the growing season for tomatoes, especially in warmer parts of the United States.
"If you average the amount of sunlight you receive each winter, it seems we don't need extra light," said owner Ryan Patterson. If the plants don't get what they need for three consecutive days of cloudy weather, they don't grow or grow fast. The tomatoes under the lumigrow lamp are more vigorous than those without the lamp.
Patterson only installed artificial lighting on its one-third farms and recorded the results. In the early stages of plant growth, he says, thicker stems are more advantageous, and in artificial lighting the diameter of a plant is 0.63 inches larger than the diameter of a plant without artificial illumination.
The size of the plant lighting based on LEDs can also be adjusted. As backyard gardeners, consumers can find LED lights like the biggest commercial farmers. For example, the Swedish Heliospectra system also includes the provision of water control for customers.
In fact, the potential of horticultural LED lighting sales is impossible to predict, especially when research has found new ways to increase productivity using solid-state lighting. But like ordinary LED lighting, growers have some problems with LED technology. "Many growers have a bad experience with LEDs," says Hubbell's Veltri. "Many of the early products do not conform to specifications and are from small suppliers or overseas manufacturers with insufficient experience in designing complex solid-state lighting systems."
However, the advantages of LEDs will enable most growers to adopt the technology at some point (Figure 4). Osram's Peiler points out that applications such as "near-distance lighting for lettuce" can only use LEDs. She added: "Today we are sure to see more activity." ”
Figure 4. The top figure shows that plants thrive under the nutriled illumination of Hubbell Lighting, while the other three shows that the city's lettuce farm uses LED lamps developed by GE Japan Inc. to increase production in controlled environments.
Ongoing research is both good and bad. Academia may eventually provide different spectra for each type of plant. With regard to the selection and combination of LEDs, Hubbell's Veltri said: "It all depends on the type of plant you are planting, and they all use different spectra." "Clearly, the concept of intelligent lighting and tunable spectroscopy is important in gardening.