Effects of atmospheric CO2 enrichment on phloem sap composition and root nitrogen accumulation in oilseed rape Effects of Nitrogen Nutrition on Photosynthetic Functions of Wheat Leaves under Elevated Atmospheric CO2 Concentration Effects of nitrogen application rates on photosynthetic energy utilization in wheat leaves under elevated atmospheric CO2 concentration Effect of atmospheric CO2 enrichment on soil microbes and related factors Effects of Abiotic Factors on Forest Net Ecosystem Production