酚酸环境中杨树细根解剖特征对铵硝比的响应
首发时间:2017-11-24
摘要:土壤环境对林木细根生长具有重要影响。本研究通过设计不同酚酸水平(0X 、0.5X、1.0X, X为田间土壤酚酸含量),以及不同氮素铵硝比(1:3、1:7、1:14),探究土壤中酚酸累积和无机氮素对欧美杨107细根解剖特征的影响。结果表明:(1)杨树不同根序细根解剖结构存在显著差异;高级根序细根横剖面直径、维管束直径和维根比均显著增大。(2)酚酸环境中,杨树1-2级细根剖面直径显著减小,但3级以上细根横剖面直径受酚酸抑制作用显著减小,说明酚酸对根系生长的抑制主要体现在低根序细根。在无酚酸环境中,铵硝比为1:3时1-3级细根横剖面直径最大,4-5级细根剖面直径最小;酚酸环境细根剖面直径受铵硝比的影响呈现出与无酚酸环境基本一致规律。(3)酚酸抑制细根皮层的发育;在酚酸环境中,铵硝比1:7时杨树1-2级细根皮层厚度均显著小于铵硝比1:3和1:14,说明任一氮素形态含量占比较高时均会促进细根皮层发育。上述结果说明,酚酸和铵硝比对细根形态构建具有相反作用,杨树人工林根际土壤酚酸的累积将显著抑制低级细根的形态构建,并可能对其吸收作用产生影响;而增加土壤中硝态氮的比例可在一定程度上拮抗酚酸的累积效应。
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The responses of polar fine roots anatomical traits to NH4:NO3 ratios in phenolic acids environment
Abstract:Soil environmental factors have an important influence on the growth of fine roots in forest trees. In this study, through the design of different phenolic acids levels (0X, 0.5X, 1.0X, X was the content of phenolic acids in soils), and different forms of nitrogen in ammonium nitrate ratio (NH4 - N:NO3- - N = 1:3,1:7,1:14), to explore the impact of phenolic acids and inorganic nitrogen on the fine root morphology construction of Populus × euramericana.The results showed that, 1) there were significant differences in the anatomical structure of different order roots. The section diameter and vascular diameter in the high-order roots were increased significantly. 2) In phenolic acids environment, the cross-section diameters of the first- and second-order roots were decreased significantly, while the cross-section diameters showed less inhibitory by phenolic acids. In the environment without phenolic acids, the cross-section diameters of 1-3 order roots were increased by 1:3 treatment, which was consistent with that in phenolic acids environment. 3) Phenolic acids inhibitted the development of root cortical layers. In phenolic acids environment, the thickness of cortical layers in 1-2 order roots was decreased by 1:7 treatment, indicating the root cortical tissues were affected by nitrogen forms. Totally, phenolic acid and ammonium nitrate ratio had an opposite effect on fine root growth. The study imply the accumulation of phenolic acids in the rhizosphere soil of poplar plantations will significantly inhibit the morphological construction of the lower-order fine roots, and enven have a potential effect on their absorption function. It could be helpful to inhibit the effect of phenolic acids to some extent, by increasing the proportion of nitrate in soil.
Keywords: fine root anatomy, nitrogen availability, phenolic acids, poplar, root-soil interaction
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