Pedosphere 29(3): 374--387, 2019
ISSN 1002-0160/CN 32-1315/P
©2019 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Paddy System with a Hybrid Rice Enhances Cyanobacteria Nostoc and Increases N2 Fixation
MA Jing1,2, BEI Qicheng1, WANG Xiaojie1,2, LIU Gang1, Georg CADISCH3, LIN Xingwu1, ZHU Jianguo1, SUN Xiaoli1, XIE Zubin1
1State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008(China);
2University of Chinese Academy of Sciences, Beijing 100049(China);
3Institute of Agricultural Sciences in the Tropics(Hans-Ruthenberg-Institute), University of Hohenheim, Stuttgart 70593(Germany)
      Biological nitrogen (N) fixation (BNF) plays a significant role in maintaining soil fertility in paddy field ecosystems. Rice variety influences BNF, but how different rice varieties regulate BNF and associated diazotroph communities has not been quantified. Airtight, field-based 15N2-labelling growth chamber experiments were used to assess the BNF capacity of different rice varieties. In addition, both the 16S rRNA and nifH genes were sequenced to assess the influence of different rice varieties on bacterial and diazotrophic communities in paddy soils. After subjecting a rice-soil system to 74 d of continuous airtight, field-based 15N2 labelling in pots in a growth chamber, the amounts of fixed N were 22.3 and 38.9 kg ha-1 in inbred japonica (W23) and hybrid indica (ⅡY) rice cultivars planted in the rice-soil systems, respectively, and only 1%-2.5% of the fixed N was allocated to the rice plants and weeds. A greater abundance of diazotrophs was found in the surface soil (0-1 cm) under ⅡY than under W23. Sequencing of the 16S rRNA gene showed significantly greater abundances of the cyanobacterial genera Nostoc, Anabaena, and Cylindrospermum under ⅡY than under W23. Sequencing of the nifH gene also showed a significantly greater abundance of Nostoc under ⅡY than under W23. These results indicate that the hybrid rice cultivar (ⅡY) promoted BNF to a greater extent than the inbred rice cultivar (W23) and that the increase in BNF might have been due to the enhanced heterocystous cyanobacteria Nostoc.
Key Words:  biological nitrogen fixation,nifH gene,15N2 labelling,rice variety,16S rRNA gene
Citation: Ma J, Bei Q C, Wang X J, Liu G, Cadisch G, Lin X W, Zhu J G, Sun X L, Xie Z B. 2019. Paddy system with a hybrid rice enhances cyanobacteria Nostoc and increases N2 fixation. Pedosphere. 29(3):374-387.
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