Relationship between the oxygen isotope ratios of terrestrial plant cellulose, carbon dioxide, and water.

The ratios of oxygen-18 to oxygen-16 ( (18)O/(16)O) of cellulose purified from two sets of wheat plants grown under conditions similar in all respects except for a large difference in the (18)O/(16)O ratios of the carbon dioxide supplied to them differ by only a small amount. The difference in the (18)O/(16)O ratios of the cellulose is similar to that observed for the (18)O/(16)O ratios of the water present in the plants. These results indicate that the oxygen derived from carbon dioxide undergoes complete exchange with the oxygen of the water in the plant during the synthesis of cellulose and that the (18)O/(16)O ratio of the water inside the plant is the primary influence on the (18)O/(16)O ratio of cellulose in terrestrial plants.