Abstract: Abstract: Characteristics of carbon fixation, followed by the previous study of dry matter accumulation in three different rice cultivars, Shanyou 63, Liangyou 2186 and IR64, were studied at the experimental farm of Fujian Agriculture and Forestry University, Fuzhou China in 2003. The results showed that the carbon contents of whole plant in the three rice cultivars, were 40.65%、41.81% and 40.44% for Shanyou 63, Liangyou 2186 and IR64 at full mature stage, respectively, and carbon contents in different rice plant parts showed the trends of grain>leaf>stem>sheath>root in order. In addition, the carbon accumulation in the three rice cultivars peaked at yellow mature stage, with a amount of 853.68 g·m-2,827.61 g·m-2 and 810.13 g·m-2 then went down to 773.17 g·m-2, 783.65 g·m-2 and 767.94 g·m-2 at full mature stage, and the amount of released oxygen reached to 2061.80 g·m-2, 2089.73 g·m-2 and 2047.84 g·m-2 in whole growing and developmental stage, which is important for maintaining the balance between CO2 and O2 in the field of rice ecosystem. From early heading stage to full heading stage, the net accumulation of carbon in Shanyou 63, Liangyou 2186 and IR 64 were 339.60 g·m-2, 369.33 g·m-2 and 309.62 g·m-2, and performanced the highest in whole growing and developmental stage, showing 43.92%, 47.13% and 40.31% of total carbon accumulation, which was considered a key stage for carbon fixing of rice. It was also shown that the three rice cultivars cost the carbon accumulated at previous developmental stages to further promote grain filling process, Shanyou 63 consumed oxygen 214.69 g·m-2 at full mature stage, which was 1.83 and 1.91 times as higher as those of Liangyou 2186 and IR64 respectively. The result implied that it appeared to be higher carbon consuming characteristics of Shanyou 63 during grain filling process, but further study is needed to elucidate its mechanism in yield formation.

Key words: Rice, Carbon cycle, Carbon accumulation, Carbon fixation