Nitrous oxide emission through plants
Nitrous oxide emission through plants
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DOI：
10.2136/sssaj1998.03615995006200010005x
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发表时间：
1998-01-01
影响因子：
2.9
通讯作者：
Nakonechny, EM
中科院分区：
文献类型：
--
作者：
Chang, C;Janzen, HH;Nakonechny, EM
农业土壤是一氧化二氮的主要来源，与温室效应的增强和平流层臭氧的消耗有关。土壤中产生的N2 O通常被认为通过扩散进入大气。我们假设，大量的N2 O也可能通过植物蒸腾作用排放，并进行了受控环境研究来验证这一假设。以甘蓝型油菜（Brassica napus L.）封闭在室内，和N2 O排放量从树叶通过测量N2 O浓度的变化进行了量化以下各种土壤处理。在现场容量，处理不利于反硝化，有没有可测量的排放N2 O从植物叶片。在饱和状态下，然而，N2 O浓度在拍摄室增加一致的时间。在采样期结束时，在拍摄室中的N2 O浓度为0.45 L L-1，远高于在土壤顶部空间（0.35 L L-1），表明N2 O从拍摄，而不是土壤中释放。用浓度约为8 mL L-1的N2 O溶液浇灌土壤，导致N2 O从芽中几乎立即释放，表明N2 O不是由植物直接产生的，而是通过蒸腾流输送到大气中。实验使用大麦（Hordeum vulgare L.）产生的结果与油菜相似，表明植物排放N2 O可能是一种普遍现象。这些结果表明，高地作物的N2 O排放的机制，并暗示，N2 O释放的测量单独从土壤表面可能会低估实际通量的农业生态系统。
Agricultural soils are a major source of N2O that has been linked to an enhanced greenhouse effect and the depletion of stratospheric ozone. The N2O produced in the soil is usually assumed to enter the atmosphere by diffusion. We postulated that significant amounts of N2O may also be emitted via plant transpiration, and conducted a controlled environment study to test this hypothesis. The shoots of canola (Brassica napus L.) were enclosed in chambers, and N2O emission from the foliage was quantified by measuring changes in N2O concentration following various soil treatments. At field capacity, a treatment not conducive to denitrification, there was no measurable emission of N2O from the plant foliage. At saturation, however, N2O concentration within the shoot chamber increased consistently with time. By the end of the sampling period, the N2O concentration in the shoot chamber was 0.45 L L-1, well above that in the soil head space (0.35 L L-1), demonstrating that N2O was released from the shoots and not the soil. Watering the soil with a N2O solution with a concentration of approximately 8 mL L-1 resulted in almost immediate release of N2O from the shoots, indicating that the N2O was not generated by the plants directly, but merely conveyed to the atmosphere by the transpiration stream. Experiments using barley (Hordeum vulgare L.) produced results similar to those with canola, suggesting that emission of N2O from plants may be a common phenomenon. These results demonstrate a mechanism for N2O emission from upland crops, and imply that measurement of N2O release solely from the soil surface may underestimate actual fluxes hom agroecosystems.