Mechanical impedance is a primary constraint to root growth and hence the capture of soil resources. To investigate whether rooting depth and root length under mechanical impedance caused by compaction are correlated we evaluated 12 maize lines at two field sites. To distinguish between lateral and nodal roots, roots were sorted into different diameter classes. Coarse roots had diameters >1 mm and represent nodal root axes. Greater proportions of coarse roots on compacted plots were found at both field sites however results were driven by genotypic variation. Soil compaction reduced total rooting depth (in all diameter classes) and coarse rooting depth at both sites compared to non-compacted plots. Root distribution was influenced by compaction with greater root length densities closer to the soil surface. Root length and root depth were not related to each other under impeded conditions. Coarse roots of some genotypes became obstructed on the compacted plots, while other genotypes were capable of growing through the impeding soil and reached deeper soil strata resulting in differential distribution of roots through the soil profile. On compacted plots we observed genotypes with similar root depths but with contrasting coarse root lengths. The ability of roots to grow through compacted soils is therefore not dependent solely on the coarse root length formed by the root system.

机械阻抗是根系生长以及土壤资源获取的主要限制因素。为了研究压实引起的机械阻抗下的生根深度和根长是否相关，我们在两个田间地点评估了12条玉米品系。为了区分侧根和节根，将根分为不同的直径类别。粗根的直径> 1 mm，代表节根轴。在两个田间地点都在压实地块上发现了较大比例的粗根，但是结果受基因型变异的驱动。与未压实的样地相比，土壤压实降低了两个地点的总生根深度（在所有直径类别中）和粗根深度。根系分布受到压实的影响，压实的根系长度密度更大，更接近土壤表面。在障碍条件下，根长和根深互不相关。在密实地块上，某些基因型的粗根被阻塞，而其他基因型则能够通过障碍土壤生长并到达更深的土壤地层，从而导致根在土壤剖面中的分布有所差异。在紧实的地块上，我们观察到了具有相似根深但根部粗细相反的基因型。因此，根系通过压实土壤生长的能力不仅取决于根系形成的粗根长度。而其他基因型则能够通过障碍土壤生长并到达更深的土壤层，从而导致根系在土壤剖面中的分布不同。在紧实的地块上，我们观察到了具有相似根深但根部粗细相反的基因型。因此，根在密实土壤中生长的能力不仅取决于根系形成的粗根长度。而其他基因型则能够通过障碍土壤生长并到达更深的土壤层，从而导致根系在土壤剖面中的分布不同。在紧实的地块上，我们观察到了具有相似根深但根部粗细相反的基因型。因此，根系通过压实土壤生长的能力不仅取决于根系形成的粗根长度。