To better understand the role of root anatomy in regulating plant adaptation to soil mechanical impedance, 12 maize lines were evaluated in two soils with and without compaction treatments under field conditions. Penetrometer resistance was 1–2 MPa greater in the surface 30 cm of the compacted plots at a water content of 17–20% (v/v). Root thickening in response to compaction varied among genotypes and was negatively associated with rooting depth at one field site under non-compacted plots. Thickening was not associated with rooting depth on compacted plots. Genotypic variation in root anatomy was related to rooting depth. Deeper-rooting plants were associated with reduced cortical cell file number in combination with greater mid cortical cell area for node 3 roots. For node 4, roots with increased aerenchyma were deeper roots. A greater influence of anatomy on rooting depth was observed for the thinner root classes. We found no evidence that root thickening is related to deeper rooting in compacted soil; however, anatomical traits are important, especially for thinner root classes.

中文翻译：

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根部解剖特征有助于玉米在压实的田间条件下扎根更深。


为了更好地了解根部解剖结构在调节植物对土壤机械阻抗的适应中的作用，在田间条件下对经过和不经过压实处理的两种土壤中的 12 个玉米品系进行了评估。在含水量为 17-20% (v/v) 时，压实地块表面 30 cm 处的贯入度阻力大 1-2 MPa。根部增厚对压实的反应因基因型而异，并且与非压实地块下某一田地的生根深度呈负相关。压实地块上的增厚与生根深度无关。根解剖结构的基因型变异与生根深度有关。根部较深的植物与皮层细胞数量减少以及节点 3 根的中部皮层细胞面积更大有关。对于节点 4，通气组织增加的根是更深的根。对于较细的根类，观察到解剖结构对生根深度的影响更大。我们没有发现任何证据表明根部增厚与压实土壤中更深的根系有关；然而，解剖特征很重要，特别是对于较细的根类。