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New Light on Rice

A Japanese researcher says artificial lighting is harming the country's main staple crop, rice. He's finding that streetlamps are impacting the plants' growth. He has come up with a bright idea to solve the problem.

An exhibit at a recent lighting equipment show in Tokyo drew a lot of attention. It was a special streetlight that does not have a negative effect on rice. It's the first time that such lights have been marketed in Japan.

One attendee said, "I was amazed. I didn't know about this." Another noted, "This will be very useful because there are many rice paddies near streetlights."

The streetlight was invented by Haruhiko Yamamoto, a professor at Yamaguchi University. He has been studying the effects of light pollution on rice plants for 10 years.

Yamamoto began to look into the effects of artificial lighting on crops by observing a rice paddy at the university. He found that rice plants exposed to the glare of streetlights at night experienced a delay in their development. Normally in late summer, when the nights begin to grow longer, rice plants sense that autumn is approaching and begin to produce grains. But streetlights cause the plants to sense that the days are still long, resulting in stunted growth.

Professor Yamamoto investigated the effects of light pollution on several farms. An area of one of the farms does not have streetlights. Local farmers were concerned that light pollution would affect the quality of rice and result in lower prices.

But others were also worried about safety. Farmer Satoshi Nakamura says, "Many female college students use the road in the evenings. There have been calls for putting up streetlights."

To develop a streetlight that's friendly to both humans and rice plants, Professor Yamamoto decided to find out which type of light has negative effects on rice plants. In experiments, he repeatedly used about 300 different wavelengths on rice plants. Those exposed to red light and yellow light were late in putting forth ears. But plants exposed to blue light and green light produced grains normally. Yamamoto also discovered another way to diminish the negative effects. By flickering an LED light at a rapid speed that's undetectable to human eyes he succeeded in further minimizing the effects on rice plants.

"This won't cause plants to suffer from light pollution while providing light at night,' Yamamoto says. "I have found something that serves both purposes."

The product was finally ready in March. It will soon light up footpaths and convenience stores adjacent to rice paddies. It costs twice as much as a regular streetlight, but the manufacturer intends to explore new markets.

"I am pleased that I am off to a good start to help society," Yamamoto says. "I hope this product becomes widespread throughout Japan and other East Asian countries that cultivate rice."

The light developed by Professor Yamamoto is friendly to both humans and rice plants. It is about to shine a New Light on Rice farming around Japan.

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