This year’s Nobel Prize in physics will be presented to three Japan-born scientists who invented blue-light emitting diodes. Blue LEDs have also brought tremendous results to agriculture, including energy-saving and pest control effects and the ability to control growth, shape and nutrient composition of plants. Much more can be expected from future research on the technology.
The three winners are Isamu Akasaki, professor emeritus of Meijo University, Shuji Nakamura, professor at the University of California, Santa Barbara, and Hiroshi Amano, professor of Nagoya University. Though red and green diodes had been invented in the 1960s, creation of blue diodes was regarded as a difficult challenge to be overcome in the 20th century. Akasaki and Amano together became the world’s first to develop the technology in 1989, followed by Nakamura who succeeded in finding a way to mass-produce blue LEDs.
Invention of blue LEDs completed the three primary colors of light ? red, green and blue ? which will produce white light when combined. The technology was quickly commercialized, mainly in the lighting industry, because of its energy-saving and long-lasting features. Remarkable progress has been made in applying the technology to various sectors, including agriculture which introduced energy-efficient lightings.
Eiji Goto, professor of the Graduate School of Horticulture at Chiba University and an expert in the use of LEDs in agriculture, highly evaluates blue LEDs, saying it laid the groundwork for using lighting technology in farming.
Red and blue lights are the main wave lengths of light necessary for plant growth, and it is known that plant growth can be controlled by adjusting the amount of light and irradiation time. Such lights are included in sunlight, but it was blue LEDs which enabled control of the lighting environment for nurturing plants. For instance, stronger blue light strengthens plant leaves and improves their growth capacity. It can also control flowering time, as well as changing the height of flowers and increasing certain nutrients in plants.
Fluorescent lamps, incandescent lamps and sodium lamps have been used in agriculture lighting, but LED lighting can save electricity charges by 30 to 50 percent. The new light source is introduced not only in horticultural facilities but also in cattle sheds, poultry houses and mushroom growing. Recently, the use of LEDs is especially prominent in vegetable factories. Tamagawa University conducts trial cultivation of some 20 kinds of leaf vegetables, fruit vegetables and potatoes in its research facility using blue and red LEDs. In addition to pursuing efficient cultivation, researchers are growing medicinal plants containing substances similar to anticancer drugs and lettuce containing more polyphenol than those grown outdoors.
The Ministry of Agriculture, Forestry and Fisheries has been working on research projects to establish technology utilizing LEDs. Empirical research is conducted on fruits and vegetables, tea leaves, flowers, harmful insects, mushrooms and fisheries, with high hopes of efficient cultivation of farm products to counter possible risks of future food shortage. Costs of LED lighting will go down along with the improvement and spread of the technology.
In the future, it will become necessary to identify the most appropriate lighting conditions for each product. We hope the technology will pave the way for production of high value-added farm products, thus benefiting farmers and the Japanese people as a whole.
(Oct. 9, 2014)