RELATIONSHIP BETWEEN THE OXYGEN ISOTOPE RATIOS OF TERRESTRIAL PLANT CELLULOSE, CARBON-DIOXIDE, AND WATER

The ratios of oxygen-18 to oxygen-16 (18O/16O) of cellulose purified from two sets of wheat plants grown under conditions similar in all respects except for a large difference in the 18O/ 16O ratios of the carbon dioxide supplied to them differ by only a small amount. The difference in the 18O/16O ratios of the cellulose is similar to that observed for the 18O/16O 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 18O/16O ratio of the water inside the plant is the primary influence on the 18O/16O ratio of cellulose in terrestrial plants. Copyright © 1979 AAAS.