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NH4+等水溶性无机离子是细颗粒物(PM2.5)中的主要组成部分。本实验以毛白杨(Populus tomentosa)和欧美杨(Populus deltoids×Populus nigra)苗木为试材,应用15N示踪法研究2种表面结构不同的叶片对NH4+的吸收以及叶片吸收氮素后的运转和分配。结果表明:2种杨树在吸收叶面的15NH4+时存在明显差异,最大吸收速率均发生在处理后6 h,但毛白杨的最大吸收速率约为欧美杨的3倍;2种杨树叶片15N含量均在处理后24 h时达到峰值,而毛白杨叶片的15N含量约为欧美杨的4倍;叶片施用15N标记的硫酸铵溶液还可以显著增加2种杨树叶片氮素水平,处理7 d后毛白杨和欧美杨叶片全氮含量分别达到对照的1.26和1.36倍;植株各器官的氮素分配率(Ndff)值显示,功能叶吸收的氮素向植株上部和下部均有运输,毛白杨主要积累于茎部,而黑杨则将氮素运输至根系;处理7 d后叶片标记溶液的施用在不同程度上增强了2种杨树叶片的净光合速率,但对叶片的气孔导度无明显影响。
Water-soluble inorganic ions such as NH4 + are the major components of the fine particulate matter (PM2.5). In this study, Populus tomentosa and Populus deltoids × Populus nigra seedlings were used as materials to study the uptake of NH4 + and the uptake of nitrogen by leaves of two species with different surface structures distribution. The results showed that there was a significant difference in the absorption of 15NH4 + between the two poplars. The maximum absorption rate occurred at 6 h after the treatment, but the maximum absorption rate of Populus tomentosa was about 3 times that of Populus tomentosa. The content of 15N in Populus tomentosa leaves was about 4 times higher than that in Populus tomentosa. The leaves of 15N labeled ammonium sulfate solution could significantly increase the nitrogen level of two poplar leaves, The total nitrogen content of Populus tomentosa and Populus euphratica leaves were 1.26 and 1.36 times that of the control respectively. The nitrogen distribution rate (Ndff) value of all organs showed that the nitrogen absorbed by functional leaves was transported to the upper and lower parts of the plant, Which mainly accumulated in the stem, while the black poplar transported nitrogen to the root system. After 7 days of treatment, the application of leaf marker solution enhanced the net photosynthetic rate of two poplar leaves to varying degrees, but the stomatal conductance Clearly affected.