Respiration in a future, higher‐CO2 world

Abstract

Abstract. Apart from its impact on global warming, the annually increasing atmospheric [CO 2] is of interest to plant scientists primarily because of its direct influence on photosynthesis and photorespiration in C 3 species. But in addition, ‘dark’ respiration, another major component of the carbon budget of higher plants, may be affected by a change in [CO 2] independent of an increase in temperature. Literature pertaining to an impact of [CO 2] on respiration rate is reviewed. With an increase in [CO 2], respiration rate is increased in some cases, but decreased in others. The effects of [CO 2] on respiration rate may be direct or indirect. Mechanisms responsible for various observations are proposed. These proposed mechanisms relate to changes in: (1) levels of nonstructural carbohydrates, (2) growth rate and structural phytomass accumulation, (3) composition of phytomass, (4) direct chemical interactions between CO 2 and respiratory enzymes, (5) direct chemical interactions between CO 2 and other cellular components, (6) dark CO 2 fixation rate, and (7) ethylene biosynthesis rate. Because a range‐of (possibly interactive) effects exist, and present knowledge is limited, the impact of future [CO 2] on respiration rate cannot be predicted. Theoretical considerations and types of experiments that can lead to an increase in the understanding of this issue are outlined.