Respiration costs associated with nitrate reduction as estimated by 14CO2 pulse labeling of corn at various growth stages
Respiration costs associated with nitrate reduction as estimated by 14CO2 pulse labeling of corn at various growth stages
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DOI：
10.1007/s11104-009-0169-9
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发表时间：
2010-04
期刊：
影响因子：
4.9
通讯作者：
O. Gavrichkova;Y. Kuzyakov
中科院分区：
文献类型：
--
作者：
O. Gavrichkova;Y. Kuzyakov
氮素以硝态氮（NO3−）或铵态氮（NH4+）离子的形式利用会影响植物的碳水化合物代谢和能量收支。最近的研究表明，NO3−转化为NH4+的费用主要发生在根系和黑暗时期。用15n标记的硝态氮和铵态氮对玉米进行施肥，并在V6和V8生长阶段对植物在14co2大气中进行脉冲标记，使我们能够评估N形态对土壤co2外排的影响。双氰胺的加入抑制了NH4+的氧化。对于铵，硝酸盐的添加使玉米根源co2外排在V6期增加2.6倍，在V8期增加1.8倍。土壤co2外排峰值的时间在两个生长阶段之间也存在差异：在V6时，外排仅在脉冲标记后的第二天达到峰值，而在V8时，在前6小时内达到峰值。NO3−和NH4+对根呼吸的强烈影响需要在模拟土壤呼吸变化时考虑土壤中的N形态和植物中硝酸盐还原位点的位置，并在单独估计对土壤总co2外排有贡献的单个co2源时。
Utilization of nitrogen in the form of either nitrate (NO3−) or ammonium (NH4+) ions may affect the carbohydrate metabolism and energy budget of plants. Recent studies showed that greater expenses of NO3−to NH4+reduction mostly occur in the roots and during darkness. Fertilization of corn with15N-labeled nitrate and ammonium, combined with pulse labeling of plants in a14CO2atmosphere at the V6 and V8 growth stages, allowed us to evaluate the effect of N form on the CO2efflux from soil. NH4+oxidation was inhibited by adding dicyandiamide. In respect to ammonium, nitrate addition increased root-derived CO2efflux from corn by 2.6 times at stage V6 and by 1.8 times at stage V8. The time of peak14CO2efflux from soil also differed between two growing stages: at V6, efflux peaked only on the second day after pulse labeling, while at V8 this occurred within the first 6 h. The strong effect of NO3−and NH4+on root respiration requires considering the N form in the soil and the nitrate reduction site location in a plant when modeling soil respiration changes and when separately estimating individual CO2sources that contribute to the total soil CO2efflux.