Foliar uptake and release of inorganic nitrogen compounds in Pinus sylvestris L. and Picea abies (L.) Karst.
Foliar uptake and release of inorganic nitrogen compounds in Pinus sylvestris L. and Picea abies (L.) Karst.
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DOI：
10.1111/j.1469-8137.1992.tb01081.x
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发表时间：
1992-03
期刊：
影响因子：
9.4
通讯作者：
E. J. Wilson
中科院分区：
文献类型：
--
作者：
E. J. Wilson
摘要 通过将当年的欧洲赤松 (Pinus sylvestris L.) 和挪威云杉 [Pica abies (L.) Karst] 的嫩枝浸入不同氮浓度的 NH4+- 或 NO3−-rain 溶液中，研究了叶面对无机氮化合物的吸收和释放。研究了氮形态、氮浓度和树种对离子流入和流出的影响。云杉芽从外部溶液中吸收NH4+。吸收显然是通过扩散发生的，而不是普遍接受的通过 H+ 或碱性阳离子交换发生的，并且随着外部溶液中 NH4+ 浓度的增加而线性增加。相反，松树芽向外部溶液释放NH4+。云杉和松树的不同反应可能反映了物种理化性质的差异或组织氮浓度的差异。如果是后者，树木的氮状态可能决定树冠是作为 NH4+ 的源还是汇，影响针表面的沉积速率。结果表明，当针表面的 NH4+ 浓度超过 4 mg 1−1 时，叶面吸收可能对氮状态做出重大贡献。在缺乏 NH4+ 基阳离子交换的情况下，大气中 NH4+ 向树冠的输入似乎不太可能直接导致荷兰森林衰退的典型养分缺乏。云杉和松树的芽都不能利用外部溶液中的NO3−，并且通常会释放NO3−。湿沉积的 NO3− 叶面积累造成的不利影响似乎不太可能出现。然而，比本实验模拟更高的 NO3− 浓度和更长的停留时间可能会导致田间叶面吸收 NO3−。
summary Foliar uptake and release of inorganic nitrogen compounds were studied by immersing current-year shoots of Scots pine (Pinus sylvestris L.) and Norway spruce [Pica abies (L.) Karst] in either NH4+- or NO3−-rain solutions at different N concentrations. The effects of N form, N concentration and tree species on ion influx and efflux were investigated. Spruce shoots absorbed NH4+ from the external solution. Uptake apparently occurred by diffusion rather than by H+ or base cation exchange as commonly accepted, and increased linearly with NH4+ concentration in the external solution. In contrast, pine shoots released NH4+to the external solution. The different reactions of spruce and pine may reflect species differences in physical and chemical properties or differences in tissue N concentration. If the latter is the case, a tree's N status may determine whether the canopy acts as a source or sink for NH4+ influencing deposition rates to the needle surface. The results show that where NH4+ concentration on the needle surface exceeds 4 mg 1−1, foliar uptake may make a significant contribution to N status. In the absence of NH4+-base cation exchange, atmospheric inputs of NH4+to the canopy appear unlikely to be directly-responsible for the nutrient deficiencies typical of Dutch forest decline. Neither spruce or pine shoots were able to utilize NO3− in the external solution and generally released NO3−. Adverse effects resulting from foliar accumulation of wet-deposited NO3− appear unlikely. However, higher NO3− concentrations and longer residence times than simulated in this experiment may result in foliar uptake of NO3− in the field.