Visualization and quantification of root exudation using 14C imaging: challenges and uncertainties
Visualization and quantification of root exudation using 14C imaging: challenges and uncertainties
复制标题
DOI：
10.1007/s11104-019-03956-8
复制
发表时间：
2019-04-01
期刊：
影响因子：
4.9
通讯作者：
Kuzyakov, Yakov
中科院分区：
文献类型：
--
作者：
Holz, Maire;Zarebanadkouki, Mohsen;Kuzyakov, Yakov
根系分泌物是土壤微生物重要的碳源和能源，但其空间分布的定量研究具有挑战性。我们测试了C-14成像（模拟以前的放射自显影）是否可以用来定量估计根分泌物的空间分布在根际methodsFirst，C-14（-）射线在土壤和水中的衰减系数进行测量和预期的C-14在根际梯度进行建模。结果C-14在土壤中的衰减系数为148 cm（-1），在水中的衰减系数为67 cm（-1），对应于C-14（-）射线穿过干燥土壤的最大距离为0.37mm。根据测得的系数，我们计算了渗出强度，根半径和根的位置上成像的C-14信号的效果。成像信号的分布受到以下因素的强烈影响：a）根中的C-14活性，B）根半径，c）从根表面到成像屏幕的距离，d）土壤中根分泌物的量，以及e）存在气隙（或具有高孔隙度的区域）之间的土壤和成像屏幕。结论忽略这些因素的影响（a-e）可能会导致偏见的根分泌物的估计使用C-14成像的根际。因此，C-14成像方法应伴随着对这些因素的准确测量和对穿过土壤的（-）射线透射率的计算。
Background and aimsRoot exudation is an important carbon (C) and energy source for soil microorganisms but quantifying its spatial distribution is challenging. We tested whether C-14 imaging (analogue of previous autoradiography) can be used to quantitatively estimate the spatial distribution of root exudates in the rhizosphere.MethodsFirst, the attenuation coefficient of C-14 (-) rays in soil and in water was measured and expected gradients of C-14 in the rhizosphere were modelled. Secondly, barley plants were pulse labelled in (CO2)-C-14 atmosphere and the origin (roots or root exudation) and locations of C-14 signal in soil were detected with imaging.ResultsThe attenuation coefficient of C-14 was 148cm(-1) for soil and 67cm(-1) for water, corresponding to a maximum distance that C-14 (-) rays pass through a dry soil of 0.37mm. Based on the measured coefficients we calculated the effect of exudation intensity, root radius and root position on the imaged C-14 signal. The distribution of the imaged signal was strongly affected by: a) C-14 activity in the root, b) root radius, c) distance from the root surface to the imaging screen, d) amount of root exudates in the soil, and e) presence of an air gap (or a region with high porosity) between the soil and the imaging screen.ConclusionsNeglecting the effects of these factors (a-e) may cause biases in the estimation of root exudates using C-14 imaging of the rhizosphere. The C-14 imaging approach should therefore be accompanied by accurate measurement of these factors and calculation of the (-) ray transmission through the soil.