Cycling of rice rhizodeposits through peptide-bound amino acid enantiomers in soils under 50 and 2000 years of paddy management
Cycling of rice rhizodeposits through peptide-bound amino acid enantiomers in soils under 50 and 2000 years of paddy management
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DOI：
10.1016/j.soilbio.2013.05.026
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发表时间：
2013-10
影响因子：
9.7
通讯作者：
P. Roth;E. Lehndorff;A. Hahn;P. Frenzel;W. Amelung
中科院分区：
文献类型：
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作者：
P. Roth;E. Lehndorff;A. Hahn;P. Frenzel;W. Amelung
水稻在淹水条件下的种植可能表现出较低的氮利用效率，然而，植物向根际释放有效的碳源，从而控制土壤有机氮的动态，尽管速率尚不清楚。本文研究了水稻短期和长期种植对根际氮通过土壤蛋白质循环的影响。为此，在中国水稻种植50年和2000年形成的土壤上，在分蘖后期用13co2 （3000 ppmv）标记3天，在温室中种植水稻。在标记后1、3、11和16天，散装和化合物特异性同位素分析可以分别在土壤总有机质（SOM）和肽结合氨基酸对映体中追踪13c标签。在蛋白质水解之前，用1M盐酸除去游离氨基酸。田间（101-114 g C kg Corg−1）的氨基酸浓度与温室土壤样品（90-124 g C kg Corg−1）相似，尽管后者完全由根际土壤组成。一天后，在SOM中已经发现了13c标签（每公斤土壤2.8-5.8毫克13c），在第3天标签结束时达到最大10.3毫克kg - 1。大约15%的13c以氨基酸的形式被回收，主要是l-形式，特别是在丙氨酸(max。180±5 mg kg - 1氨基酸- c，第3天)，这可能是根系分泌物的代表。只有丙氨酸中过量的13c表现出显著的时间动态，而大量SOM中过量的13c没有表现出显著的时间动态，表明根沉积物与肽结合的土壤氨基酸结合。细菌残留标记谷氨酸对13c信号的吸收迟缓，不受水稻管理时间的影响。
Rice cultivation under submerged conditions may exhibit low N use efficiency, however, plants release available C sources into the rhizosphere and therewith control the dynamics of soil organic nitrogen, though at yet unknown rates. Here we studied the cycling of rhizosphere N through soil proteins, as affected by short- and long-term lowland rice cultivation. For this purpose, rice was grown in the greenhouse on soils formed under 50 and 2000 years paddy rice cultivation in China and labeled for three days during late tillering stage using13CO2(3000 ppmv). Bulk and compound-specific isotope analysis allowed for tracing the13C-label in total soil organic matter (SOM) and peptide-bound amino acid enantiomers after 1, 3, 11 and 16 days after labeling, respectively. Free amino acids had been removed with 1M HCl prior to protein hydrolysis.Amino acid concentrations were similar in field (101–114 g C kg Corg−1) as in greenhouse soil samples (90–124 g C kg Corg−1), even though the latter completely consisted of rhizosphere soil. After one day the13C label was already found in SOM (2.8–5.8 mg13Cexcessper kg soil), peaking to a maximum of 10.3 mg kg−1at the end of the labeling at day 3. About 15% of this13C was recovered in amino acids, mainly in the L-forms, and particularly inl-alanine (max. 180 ± 5 mg kg−1amino acid-C, day 3), which was likely representative for root exudates. Only the excess13C inl-alanine but not in bulk SOM showed significant temporal dynamics, indicating incorporation of rhizodeposits into the peptide-bound soil amino acids. The bacterial residue markerd-glutamic acid showed a retarded incorporation of the13C signal, without being affected by the duration of paddy management.