Microbial response to rhizodeposition depending on water regimes in paddy soils

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• 作者：Jing Tian ; Michaela Dippold ; Johanna Pausch ; Evgenia Blagodatskaya ; Mingsheng Fan ; Xiaolin Li ; Yakov Kuzyakov
• 关键词：13CO2 pulse labeling ; Rhizodeposition ; Phospholipid fatty acids (PLFAs) ; Microbial community structure ; Water conservation techniques ; Paddy soil ; Root exudation
• 刊名：Soil Biology & Biochemistry
• 出版年：2013
• 出版时间：October, 2013
• 年：2013
• 卷：65
• 期：Complete
• 页码：195-203
• 全文大小：605 K

文摘

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 ¹³CO₂ and the incorporation of rhizo-C into specific microbial groups was determined by 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 ¹³C incorporation into microorganisms compared to the non-flooded and alternating water regimes treatments. Continuous flooding caused a relative increase of ¹³C incorporation in Gram positive bacteria (i14:0, i15:0, a15:0, i16:0, i17:0, a17:0). In contrast, Gram negative bacteria (16:1¦Ø7c, 18:1¦Ø7c, cy17:0, cy 19:0) and fungi (18:2¦Ø6, 9c, 18:1¦Ø9c) 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 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.