Effects Of Elevated Ozone Concentration On Respiration Rate And N₂O Emission From Soil-Crop System

Winter-wheat and soybean, conventional crops in our country with large planting area, were selected as the experimental material. Field experiments including two winter-wheat growing seasons and one soybean growing season were carried out. Two treatments were set up:control (CK), elevated O3 radiation (T). To investigate the influence of elevated O3 radiation on respiration rate and N2O emission from soil-crop system, respiration rate and N2O fluxes were analyzed by static chamber-gas chromatography method, investigate Chlorophyll content, Nitrate reductase activities and soluble protein content in leaves, as well as total nitrogen content, nitrate nitrogen content amd ammonia nitrogen content in leaves and soil.Furthermore, this study will provide the base to objective evaluate the ecological effect of elevated O3 radiation addition, as well as to estimate the regional farmland greenhouse gas emission and its'long term tendency in farmland. Results indicated that:Elevated O3 radiation did not change the seasonal pattern of respiration rate, T1 significantly declined mean respiration rate (MRR) by 26.8%(p=0.000), T2 significantly declined mean respiration rate (MRR) by 45.6%(p=0.000); T1 significantly declined mean N2O flux (MNF) by 23.1%(p=0.000), T2 significantly declined mean N2O flux (MNF) by 27.5%(p=0.000) from winter-wheat system.T did not change the seasonal pattern of respiration rate and N2O emission from soil-soybean system. T1 and T2 had a negative effect on MRR, which significantly declined by 23.5% (p=0.000) and 20.2%(p=0.000).Respectively, during turning green stage and jointing-booting stage, T did not change the seasonal pattern of N2O emission.An obvious diurnal variation of respiration rate was observed in soil-winter wheat system, which did not changed by T. And N2O emission showed a random diurnal variation from soil-winter wheat system.There be some effect on aboveground, underground and total dry matter yield, Chlorophyll content, Nitrate reductase activities and soluble protein content in leaves, as well as total nitrogen content, nitrate nitrogen content amd ammonia nitrogen content in leaves and soil, which caused the influence of T on respiration rate and N2O emission from soil-crop system.