Effect of free-air atmospheric CO2 enrichment on dark respiration of rice plants (Oryza sativa L.)

Abstract

Abstract Elevated carbon dioxide (CO 2 ) has been shown to have variable effects on plant respiration rates in publications. However, there is little measurement of dark respiration rate of rice plant ( Oryza sativa L.) conducted in free-air CO 2 enrichment (FACE). In this study, seasonal variation in the effect of elevated CO 2 on dark respiration of aboveground rice was investigated by FACE experiments in Wuxi city, Jiangsu province of China. The results showed that increasing the present atmospheric CO 2 concentration by 200 μmol mol −1 did not significantly affect the specific dark respiration coefficient ( R dw25 ) of aboveground rice plants expressed on the basis of dry weight biomass throughout the growth season, which may be attributed to no significant effect of the elevated CO 2 on the nitrogen content in aboveground rice plants. However, the canopy dark respiration coefficient ( R d25 ) of aboveground rice plants expressed on the basis of ground area was periodically stimulated by the elevated CO 2 by about 17% as the elevated CO 2 significantly increased aboveground rice biomass over the entire rice season. This study indicates that free-air atmospheric CO 2 enrichment did not significantly affect the specific respiration coefficient of aboveground rice plants while it significantly stimulated the canopy respiration coefficient.