Growth characteristics and grain yield of rice (Oriza sativa L.) and CO₂ exchange rate of the rice plants at photo- and dark periods were examined in a plant growth chamber installed with a microwave-powered lamp. Photosynthetic photon flux density was about 1 mmol m^-2 S^-1 at the plant canopy level. The grain yield per unit cultivation area was 0.7kg m^-2 96 days after seeding. The CO₂ exchange rate (the net photosynthetic rate) at the photoperiod was 3.5mg CO₂m^-2s^-1 43 days after seeding and then decreased to 0.5_mg CO₂ m^-2 s^-1 at the harvest time. The microwave-powered lamp is useful to cultivate rice which requires high light intensity, with less electrical energy and less thermal radiation.

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