期刊
PLANT AND SOIL
卷 440, 期 1-2, 页码 457-471出版社
SPRINGER
DOI: 10.1007/s11104-019-04070-5
关键词
Extracellular enzymes; Microbial growth kinetics; Litter quality; Priming mechanism; Soil fertility; Root exudation
资金
- National Key Research and Development Program of the Ministry of Science and Technology of China [2016YFD0600204]
- State Key Program of National Natural Science Foundation of China [31530007]
- Sanxin Forestry Project in Jiangsu Province [LYSX[2016]46]
- Water Conservancy Science and Technology Project of Jiangsu Province [2018063]
- National Natural Science Foundation of China [31870598]
- specimen platform of China [2005DKA21403-JK, 2005DKA21400]
- teaching specimens sub-platform [2005DKA21403-JK, 2005DKA21400]
Background and aims Root exudation can prime microbial synthesis of additional exoenzymes and consequently accelerate organic carbon (C) and nitrogen (N) mineralization. Such exudate induced priming effect (EPE) has been hypothesized to depend on exudate rate and stoichiometry. Little is known about how EPE would affect litter decomposition. We employed a microcosm experiment to evaluate the influence of root exudate on litter nutrient release and microbial enzyme functions. Methods Leaf litters of Pinus massoniana, Quercus variabilis and Robinia pseudoacacia were incubated under two soil conditions (fertile versus barren). Solutions of chemicals often found in root exudates with contrasting C:N ratios were inoculated frequently into the microcosms to simulate exudation. By comparing with a water control, exudate effect was determined. Results In barren soils, exudates with C:N ratio of 10 significantly decelerated C loss of R. pseudoacacia, all N-containing exudates significantly enhanced the N-cycling related enzymes in decomposing Q. variabilis, while C-only exudate accelerated N loss of P. massoniana. In fertile soils, C-only exudate promoted the N-cycling related enzymes in decomposing R. pseudoacacia. Conclusions A stoichiometric C:N constraint on microbial utilization of exudates arose in decomposing recalcitrant litters in barren soil. EPE and its stoichiometric constraint depend on interactions with litter quality and soil condition. The findings arouse the consequences of exudate rate and stoichiometry changes in determining soil nutrient balance.
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