Diode lights, which work by passing a current between semiconductors, have come a long way since they showed up in calculator displays in the 1970s. Compared with other forms of electrical illumination, light-emitting diodes use less energy, give off little heat and can be manipulated to optimize plant growth.
In agricultural applications, LED lights are used in ways that seem to border on alchemy, changing how plants grow, when they flower, how they taste and even their levels of vitamins and antioxidants. The lights can also prolong their shelf life.
The visible spectrum is measured in minuscule wavelengths, shifting at one end from violet-blue light through green to red at the other. For decades, scientists have known that photosynthesis is optimized within the red band, but plants also need blue lightwaves to prevent stretching and enhance leaf color. A barely visible range beyond red, known as far red, promotes larger leaves, branching and flowering. With advances in LED technology, light recipes — determining the number of hours illuminated, the intensity of photons directed at plants and the mix of colors — can be finely tuned to each crop and even to each stage in a crop’s life.
Given the evolving nature of the technology and its enormous commercial potential, light manufacturers and universities, often in collaboration, are actively involved in research and development.