LEDs coax plants to grow

Caren B. Les, News Editor, caren.les@photonics.com

Does talking to plants really help them grow? That’s debatable. But most people would agree that plants need adequate light, water and minerals to reach their full potential. Sometimes natural light is not a practical solution – as with vertical “skyscraper” farms, greenhouses and growth chambers – but now, indoor gardeners can turn to LED lighting designed to accelerate plant growth while promoting maximum size and vitality.

One LED arrangement for indoor gardening comes from Illumitex Inc. of Austin, Texas, whose Surexi Horticulture LED series, developed in partnership with university and corporate research facilities, serves as an indoor light source for the global horticultural community.

Left, plants grow under LED lighting in Illumitex Inc.’s horticulture test labs in Austin, Texas. At right, indoor LED lighting for various types of plants and growth stages is designed at Illumitex’s research labs. Images courtesy of Illumitex.

The company’s patented square light pattern and precision beam control create edge-to-edge light uniformity and ensure more even growth by exposing all plants to the same amount of light. The single-package setup eliminates color separation issues inherent in other horticultural LED lighting.

The LEDs are available in multiple wavelength combinations to help farmers and researchers target a plant’s desired photoreceptors, such as phytochrome, a pigment sensitive to light in the red and far-red regions of the visible spectrum, and cryptochrome, a blue-light-sensitive flavoprotein.

Various models meet the lighting needs of various plants and their growth stages. For general-purpose gardening, one model offers a large amount of red light as well as some blue light to spur photosynthesis during the vegetative growth stage and to facilitate flowering. A second model targets germination chambers and flower production with a higher proportion of red to blue. A third model, designed for leafy green vegetables, has much more blue light to reduce plant height, which saves space. And a fourth nurtures seedlings with an even higher blue content, producing stocky plants with short internodal distances, which are desirable at this stage of development.

The light sources also have applications in tissue culture and biopharmacology laboratories where plant-based vaccines and pharmaceuticals are developed.