Effects of elevated UVB radiation and CO₂ atmosphere on the growth and yield of rice (Oryza sativa L.) in the field.

Abstract

We have investigated the effects of elevated UVB (1 W/m²), which was provided by UVB-emitting fluorescent lamps, with cellulose diacetate film, and CO₂ atmosphere (700 ppm) on the growth and yield of rice (cv. Sasanishiki) in paddy field or in open-top-chambers in the field at Kashimadai in Miyagi Prefecture since 1993. We report the results obtained from experiments, which had been conducted since 1998. Dry mass and grain yield reduced under elevated UVB although the degree of reduction varied depending on the year. Irrespective of change in weather in each year, grain size became smaller and grain protein content, especially glutelin, significantly increased both in higher CO₂ atmosphere and in ambient CO₂ atmosphere. The ripening stage of seed was most sensitive to elevated UVB to cause grains smaller and to cause grain protein content higher throughout the life cycle of rice.