Soil Biology and Biochemistry, Oct, 2013, Vol.65, p.195(9)
To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.soilbio.2013.05.021 Byline: Jing Tian, Michaela Dippold, Johanna Pausch, Evgenia Blagodatskaya, Mingsheng Fan, Xiaolin Li, Yakov Kuzyakov Abstract: Rhizodeposit-carbon (rhizo-C) serves as a primary energy and C source for microorganisms in the rhizosphere. Despite important progress in understanding the fate of rhizo-C in upland soils, little is known about microbial community dynamics associated with rhizo-C in flooded soils, especially depending on water regimes in rice systems. In this study, rice grown under non-flooded, continuously flooded and alternating water regimes was pulse labeled with.sup.13CO.sub.2 and the incorporation of rhizo-C into specific microbial groups was determined by.sup.13C in phospholipid fatty acids (PLFAs) at day 2 and 14 after the labeling. A decreased C released from roots under continuously flooded condition was accompanied with lower total.sup.13C incorporation into microorganisms compared to the non-flooded and alternating water regimes treatments. Continuous flooding caused a relative increase of.sup.13C incorporation in Gram positive bacteria (i14:0, i15:0, a15:0, i16:0, i17:0, a17:0). In contrast, Gram negative bacteria (16:1I7c, 18:1I7c, cy17:0, cy 19:0) and fungi (18:2I6, 9c, 18:1I9c) showed greater rhizo-C incorporation coupled with a higher turnover under non-flooded and alternating water regimes treatments. These observations suggest that microbial groups processing rhizo-C differed among rice systems with varying water regimes. In contrast to non-flooded and alternating water regimes, there was little to no temporal.sup.13C change in most microbial groups under continuous flooding condition between day 2 and 14 after the labeling, which may demonstrate slower microbial processing turnover. In summary, our findings indicate that belowground C input by rhizodeposition and its biological cycling was significantly influenced by water regimes in rice systems. Author Affiliation: (a) Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193, China (b) Department of Soil Science of Temperate Ecosystems, University of Gottingen, 37077 Gottingen, Germany (c) Department of Agroecosystem Research, University of Bayreuth, 95440 Bayreuth, Germany .sup.dDepartment of Agropedology, University of Gottingen, 37077 Gottingen, Germany Article History: Received 26 January 2013; Revised 22 May 2013; Accepted 24 May 2013
Agroecosystems ; Fatty Acids ; Bacteria ; Soils ; Water
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