Article,
Rice yield enhancement by elevated CO2 is reduced in cool weather
Global Change Biology, 14 (2): 276--284 (Feb 1, 2008)
DOI: 10.1111/j.1365-2486.2007.01498.x
Abstract
The projected increase of atmospheric CO2 concentration (CO2) is expected to increase rice yield, but little is known of the effects of CO2 at low temperature, which is the major constraint to growing rice in cool climates. We grew rice under two levels of CO2 (ambient and elevated by 200 μmol mol−1) and two nitrogen (N) fertilization regimes in northern Japan in 2003 (cool weather) and 2004 (warm weather) in the field in a free-air CO2 enrichment (FACE) system. Elevated CO2 significantly increased grain yield in both years in both N regimes, but the magnitude of the increase differed between years: 6\% in 2003 vs. 17\% in 2004, with a significant interaction between CO2 and year. This difference resulted from responses of spikelet number and ripening percentage to elevated CO2. Enhancement of dry matter production and N uptake at heading by elevated CO2 was smaller in 2003 than in 2004, although at maturity there was no difference between years. No significant interaction between N regime and CO2 was detected in yield and yield components. The results suggest that yield gain due to elevated CO2 can be reduced by low temperature.
