Research on N2O emissions from maize and soybean plants

N₂O emissions from plants are the new field in greenhouse gas research. Up to now, the research on N₂O emissions from plants is still at early stage both at home and abroad. There has been few reports about the characters and amounts of N₂O emissions from different plant species during growing stage as well as the emission mechanism of N₂O in plants. In this study, using maize (C₄ plant) and soybean (C₃ plant), we firstly and synchronously measured N₂O emissions from plants during the whole growing stage, mainly focusing on the release patterns of N₂O emissions from plants and discerning the source of emitted N₂O. N₂O release fluxes and stable nitrogen isotope composition (δ¹⁵N values) of emissions by detached fresh plants and the soil were measured in 2009. The results showed that the range of N₂O emission fluxes from maize and soybean during growing stage was 0.039-3.189 ng N₂O g^-1 dry weight h^-1 and 0.053-2.648 ng N₂O g^-1 dry weight h^-1, respectively. δ¹⁵N values were in the range of 3.674⁰/₀₀ to 17.53⁰/₀₀ and 2.28⁰/₀₀ to 35.77⁰/₀₀ for maize and soybean plants, respectively, and the ones of the soil were in the range of -3.978⁰/₀₀ to -10.754⁰/₀₀ and -2.76 to -24.21⁰/₀₀. The δ¹⁵N values for N₂O released by plants were positive values, while the δ¹⁵N values of the soil N₂O were negative, which reveals that N₂O emissions from plants and the soil are two different biological processes. The results indicate that the emitted N₂O from plants is produced by physiological metabolism of plant itself. The production mecha- - nism of N₂O in plants needs to be further investigated.