[Effects of elevated atmospheric CO concentration on chemical composition of rice straw].

Rice straw is a potential material for bioenergy production. Elevated atmospheric carbon dioxide (CO) concentration changed the quantity and quality of rice straw, thus changing its bioenergy production potential. In this experiment, we collected rice straw from China Free Air CO Enrichment Platform (FACE). Three rice varieties, Wuyunjing 27, Y Liangyou 900 and Nipponbare N16, were selected from the FACE platform (the CO concentration in the experimental group was controlled at 570 μmol ·mol, which was 200 μmol ·mol higher than the control group), the chemical composition of which was analyzed. The results showed that elevated CO concentration significantly increased C content, C/N, and the content of non-structural carbohydrates in straw. Elevated CO concentration significantly increased total sugar release by 8.8%, 6.7% and 9.9% in Wuyunjing 27, Y liangyou 900 and N16, respectively. Elevated CO concentration significantly enhanced the biomass of N16 straw, but had no effect on the straw biomass of the other two rice varieties. The total sugar yield of N16 increased most significantly with elevated CO concentration, reaching 19.2%. Our results indicated that elevated CO concentration could improve the quality and quantity of rice straw, thereby increasing the utilization potential of biofuel.