When rice seedlings were grown under a light intensity of 130 umol m-2 s- 1 and double atmospheric CO2 concentaion, its photosynthetic rate was 45 % higher than the control on the first day, but was 13% and 21% lower than the control after one and two weeks respectively (Fig. 1 ); and there were also increases in flesh weight, for matter, leaf area and height of Plant after two weeks (Table 1 ). The increase Of total biomass of Plant after 2 weeks was probably due to an increase in leaf area.The total soluble Protein, the ratioof Rubisco to total soluble Pertain content, the initial and total Rubisco activities and the translatable mRNA for Rubisco on leaf area basis in rice seedlings grown under double Co concentration for two weeks (Table 2) were lower than in the control, but, the activation state Of Rubisco in rice seedlings remained unchanged(Fig. 2). When rice seedlings were grown in ed for 12 h, its Rubisco activity was dropped to 40% of original value.
