Electrical resistivity tomography (ERT) is extensively employed for monitoring soil water content (SWC) in agricultural fields. However, the direct impacts of roots and the indirect effects of root water uptake on soil electrical resistivity (ER) have been largely neglected. Furthermore, the application of ERT technology for precise measurements of crop roots in various conditions (such as cultivars and irrigations regimes) remains unexplored. This study, therefore, utilized buried fresh root experiments, soil pots, and field-irrigation trials with different winter wheat (Triticum aestivum L.) cultivars to examine the influence of fresh crop roots on ER and assess ERT’s capability to characterize root uptake and the root system size. The findings from the buried root and pot experiments demonstrated that fresh root addition significantly reduced the ER of mixed soil (sand and loam are mixed in a ratio of 1:5) when the SWC was below 0.24 cm3 cm−3. However, in loam soil, fresh root addition did not significantly decrease the ER. Pot experiments revealed strong positive correlations between root surface area and soil ER (R2 = 0.78, P < 0.001), suggesting that the increase in soil ER due to root absorption greatly outweighs the reduction caused by the roots themselves. Field experiments conducted during the grain-filling phase, when root size was stable, showed significant differences in soil ER changes (defined as the difference between two consecutive ER measurements) among winter wheat cultivars in both shallow (0–40 cm) and deep (40–100 cm) soil layers under various irrigation treatments. It was observed that wheat tends to utilize deep soil moisture in later growth stages, even with sufficient water conditions. Further analysis indicated that ER changes were positively correlated (R2 > 34, n = 50) with root surface area density (RSAD) in the 0–100 cm soil layer, particularly showing a stronger correlation with RSAD in the deep soil layer compared to the shallow layer under deficit irrigation (R2=0.65 vs. R2=0.23). In conclusion, ERT effectively characterizes the differences in root water uptake as well as root system size, especially focusing on deep roots among cultivars under various irrigation regimes.

中文翻译：

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将冬小麦 （Triticum aestivum L） 根系性状和根系水分吸收与电阻率层析成像联系起来


电阻率断层扫描 （ERT） 广泛用于监测农业领域的土壤含水量 （SWC）。然而，根系的直接影响和根系水分吸收对土壤电阻率 （ER） 的间接影响在很大程度上被忽视了。此外，ERT 技术在各种条件（如栽培品种和灌溉制度）下精确测量作物根系的应用仍有待探索。因此，本研究利用埋藏鲜根实验、土壤盆和不同冬小麦 （Triticum aestivum L.） 品种的田间灌溉试验来检查新鲜作物根系对 ER 的影响，并评估 ERT 表征根吸收和根系大小的能力。埋根和盆栽实验的结果表明，当 SWC 低于 0.24 cm3 cm-3 时，新鲜根添加显着降低了混合土壤的 ER（沙子和壤土以 1：5 的比例混合）。而在壤土中，新鲜根添加并未显著降低 ER。盆栽试验显示根表面积与土壤 ER 之间存在很强的正相关关系 （R2 = 0.78，P < 0.001），表明根系吸收引起的土壤 ER 增加大大超过根系本身造成的减少。在籽粒灌浆阶段进行的田间试验表明，在各种灌溉处理下，冬小麦品种在浅层 （0-40 cm） 和深层 （40-100 cm） 土壤 ER 变化（定义为两个连续 ER 测量值之间的差异）存在显著差异。据观察，即使在充足的水分条件下，小麦在生长后期也倾向于利用深层土壤水分。 进一步分析表明，ER 变化与 0–100 cm 土壤层的根表面积密度 （RSAD） 呈正相关 （R2 > 34， n = 50），特别是与亏缺灌溉下的浅层相比，深层土壤层与 RSAD 的相关性更强 （R2=0.65 vs. R2=0.23）。总之，ERT 有效地表征了根系水分吸收和根系大小的差异，尤其是关注不同灌溉条件下品种之间的深根。