Abstract
To elucidate the interaction between tropospheric O3 and CO2 in paddy rice, combined applications of O3 (0–0.3 cm3 m−3) and CO2 (380, 800 cm3 m−3) were performed at the vegetative stage or flowering to early maturing stage of rice plants using environmentally controlled chambers: O3 decreases growth and yield, although CO2 exhibits the opposite action. At the vegetative stage, elevated O3 decreased the relative growth rate (RGR) and net assimilation rate (NAR) but elevated CO2 ameliorated those effects. At the flowering to early ripening stage, elevated O3 decreased dry matter production and yield with lowering of the percent maturity of grains, but the elevated CO2 tended to offset these declines. The results indicate that elevated O3 primarily inhibits photosynthesis-related process of paddy rice. Elevated CO2, which is predicted for the future, interactively ameliorates that inhibition.
