Effect of CO_2 Concentration on Nitrogen Metabolism of Winter Wheat

Hoagland’s solution of water culture medium was used to study the effect of CO2elevated on nitrate metabolism of wheat under normally natural light and light-shaded conditions. NO3 -N, NH4 -N, nitrate reductase activity, total uptake N by wheat - + plants during solution cultural period and total N in plants were determined for comprehensive evaluation of the effect. Results showed that under both natural light and light-shaded conditions, addition of CO2 increased NO3 -N uptake and its assimilative - capabilities by plants. However, there were some difference between shoots and roots. With increase of CO2 concentration, the concentration of NO3 -N and NH4 -N as well as nitrate reductase activity all decreased in shoots while the difference was not so - + distinct in roots, and the nitrate reductase activity did not decrease, but increase. Since NO3 -N uptake by plants from the solution and - the total N in plants were much enhanced by CO2 addition, it may be concluded that addition of CO2 has resulted in rise of nitrate absorption, assimilation and metabolism of wheat.