Zou Jiaxun, Yao Qin, Liu Junjie, Li Yansheng, Song Fuqiang, Liu Xiaobing, Wang Guanghua
Key Laboratory of Mollisols Agroecology, Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin, China.
College of Life Science, Heilongjiang University, Harbin, China.
PeerJ. 2020 Jul 15;8:e9550. doi: 10.7717/peerj.9550. eCollection 2020.
Nitrogen-fixing microorganisms play important roles in N cycling. However, knowledge related to the changes in the diazotrophic community in response to cropping systems is still rudimentary. In this study, the gene was used to reveal the abundance and community compositions of diazotrophs in the cropping systems of continuous cropping of corn (CC) and soybean (SS) and soybean-corn rotation for growing corn (CSC) and soybean (SCS) in a black soil of Northeast China. The results showed that the abundance of the gene was significantly higher in cropping soybean than in cropping corn under the same cropping system, while remarkably increased in the rotation system under the same crop. The Shannon index in the CC treatment was significantly higher than that in the other treatments, but the OTU number and Chao1 index had no significant change among the four treatments. was the dominant diazotrophic species, and its relative abundance was at the lowest value in the CC treatment. In contrast, sp. had the highest relative abundance in the CC treatment. A PCoA showed that the diazotrophic communities were separated between different cropping systems, and the variation caused by continuous corn cropping was the largest. Among the tested soil properties, the soil available phosphorus was a primary factor in determining diazotrophic community compositions. Overall, the findings of this study highlighted that the diazotrophic communities in black soils are very sensitive to cropping systems.
固氮微生物在氮循环中发挥着重要作用。然而，关于固氮群落响应种植系统变化的相关知识仍很基础。在本研究中，利用该基因揭示了中国东北黑土中玉米连作（CC）、大豆连作（SS）以及大豆 - 玉米轮作种植玉米（CSC）和大豆（SCS）的种植系统中固氮菌的丰度和群落组成。结果表明，在相同种植系统下，种植大豆时该基因的丰度显著高于种植玉米时，而在相同作物的轮作系统中该基因丰度显著增加。CC处理中的香农指数显著高于其他处理，但四个处理间的OTU数量和Chao1指数无显著变化。是优势固氮物种，其相对丰度在CC处理中处于最低值。相反，sp.在CC处理中的相对丰度最高。主坐标分析表明，不同种植系统间的固氮群落存在分离，且玉米连作引起的变化最大。在所测试的土壤性质中，土壤有效磷是决定固氮群落组成的主要因素。总体而言，本研究结果突出表明黑土中的固氮群落对种植系统非常敏感。
