Japanese farming lore has long observed that plentiful mushroom harvests tend to follow thunderstorms. Now researchers at Iwate University in northern Japan have confirmed the legend, finding that some mushrooms more than double their yields when jolted by electricity.

The results could lead to new harvesting methods that would significantly increase food production. That's good news for a Japanese food industry where mushrooms are a popular staple, and where around 50,000 tons of mushrooms must be imported a year, mainly from China and South Korea, just to meet the high demand.

The study reached its conclusions after four years of bombarding mushrooms with artificially induced lightning, reports National Geographic. Ten varieties of mushroom were tested, and eight of those species responded by growing at an increased rate when electrified. The fungi reacted best when exposed to between 50,000 and 100,000 volts for one ten-millionth of a second.

Researchers were able to get the shiitake crop to yield double the amount usually harvested, but the best performing species were nameko mushrooms, which produced a whopping 80 percent more mushrooms.

As for why the mushrooms multiply when powered by lightning, researchers can only hypothesize at this point. But it's possible the mushrooms are giving themselves a reproductive boost in response to danger, said Yuichi Sakamoto, one of the study's chief researchers. Initially, the mushrooms are damaged by the electrical bursts, but they compensate quickly by increasing protein and enzyme secretion.

The next step for researchers is to develop machines for farmers that can deliver carefully controlled lightning-like bursts to their mushroom harvests. "We want to collaborate with commercial mushroom farmers and eventually commercialize this technology," said Koichi Takaki, an associate professor in engineering at Iwate University.

The prospects are so good that the Iwate team is testing to see if other crops also respond to lightning in this way. So far, radish, rapeseed, beans and some varieties of lily are showing increased growth rates when the proper electric current is applied.