[Effect of CO Doubling and Different Plant Growth Stages on Rice Carbon, Nitrogen, and Phosphorus and Their Stoichiometric Ratios].

The variation characteristics of ecological stoichiometric ratios can reflect the nature of plant adaptation to environmental changes. The C, N, and P contetns, and their stoichiometric ratios in different organs of rice were studied using a CO continuous labeling system, by simulating the increase of atmospheric CO concentration (800×10). The results showed that CO doubling promoted the growth of rice organs and increased the root/shoot ratio. CO doubling reduced the shoot TN content in different growth periods, increased the C/N ratio in the rice root, shoot, and grain, decreased the N use efficiency, and improved the P use efficiency. Multiple comparison and Venn diagram analyses showed that CO concentration only has a significant impact on the TN content in the rice shoot; it contributed little to the variation in rice nutrient content and their stoichiometric ratios, indicating that CO doubling had no effect on these. Under the condition of elevated atmospheric CO concentrations, the C, N, and P contents and their stoichiometirc ratios, in rice organs had good homeostasis, and the stoichiometric change during growth periods was consistent with "the Growth Rate Theory". In farmland management, appropriate nitrogen fertilizers can alleviate the nutrient balance pressure caused by the increase in CO concentration.