Japanese Firms Bet on Bubble Economy

OSAKA, Japan—Invisible to the naked eye, countless tiny bubbles injected into irrigating water are being used in experiments to grow organic tomatoes and strawberries at computerized greenhouses in western Japan’s Hyogo prefecture.

The result: larger, juicier fruit and an average yield increase of 10% to 20% compared with crops grown using tap water, says IDEC Corp., the company that operates the facility.

For some companies,...