Abstract: Dissolved oxygen (DO) plays an important role in nitrogen cycling in paddy fields and in the growth and development of rice. To deepen the understanding of the effects of DO on nitrogen transformation in paddy fields and nitrogen metabolism in rice plants is of great significance for reducing nitrogen loss in paddy fields and improving nitrogen utilization efficiency of rice. In recent years, studies have elucidated the effects of DO on soil biochemical processes such as nitrogen fixation, ammonification, nitrification and denitrification, as well as the diversity of microbial populations. In addition, a large number of studies have also proved the importance of DO for nitrogen uptake and utilization in rice. In this paper, we systematically introduced the effects of DO on microbial community structure and activity, as well as its relationship with transformation of different forms of nitrogen in paddy fields. We then reviewed the latest research progresses about the response mechanisms of rice root growth characteristics, nitrogen uptake and assimilation, and relevant amino acid metabolisms to DO. Finally, the problems and prospects of rice production were put forward according to the research status of oxygen nutrition in rice fields at the present stage.

Key words: mixed litter, total phenols, condensed tannin, degradation rate