Soil structure has a huge impact on plant root growth, but it is difficult to isolate from other soil properties in field studies, and generally overlooked in laboratory studies that use sieved and homogenised repacked soil. This study aimed to compare root and shoot growth under controlled soil conditions where only soil structure varied. Soil treatments used soil sieved to < 2 mm, packed in uniform layers to create a homogenous structure. A heterogeneous structure was packed from artificially formed aggregates created by breaking apart the homogeneous soil after intense compaction. Barley, peas and Arabidopsis, selected for contrasting root sizes, were grown under three levels of compaction (1.25 g cm, 1.40 g cm, 1.55 g cm) in both homogeneous and heterogeneous structured soils for 10 days. Penetration resistance increased from about 0.4 MPa at 1.25 g cm to 1.3 MPa at 1.55 g cm for either soil structure. Soil structure was quantified from water retention characteristics and X-ray Computed Tomography (CT) as complementary methods to assess the soil's pore size distribution and properties. Heterogenous soil had 50% more macropores at 1.55 g cm when compared to homogenous soils. Pore structure complexity in the heterogeneous structure was found to be beneficial for root growth of peas and barley but not Arabidopsis. Shoot biomass of peas grown in heterogeneous soil at 1.55 g cm increased by 65% when compared to homogenous soil, whereas barley and Arabidopsis shoot biomass did not differ significantly between any treatments. Chlorophyll, flavonoid, and nitrogen content could only be measured on barley or peas due to shoot size, but only minor differences were observed between soil structures. Soil structural heterogeneity influenced many root properties and above-ground biomass, with impacts found to be species-dependent and likely caused by the interaction between root size and preferential growth in macropores.

中文翻译：

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土壤结构复杂性对对比根系结构植物根系生长的影响

土壤结构对植物根系生长有巨大影响，但在实地研究中很难将其与其他土壤特性分开，并且在使用过筛和均质重装土壤的实验室研究中通常被忽视。本研究旨在比较在仅土壤结构变化的受控土壤条件下根和芽的生长。土壤处理使用筛分至 < 2 毫米的土壤，以均匀的层填充以形成均匀的结构。一种异质结构是由人工形成的骨料填充的，这些骨料是通过强烈压实后打碎均匀的土壤而形成的。根据根部大小的对比选择大麦、豌豆和拟南芥，在同质和异质结构土壤中在三种压实水平（1.25 g cm、1.40 g cm、1.55 g cm）下生长 10 天。对于任一土壤结构，穿透阻力从 1.25 g cm 下的约 0.4 MPa 增加到 1.55 g cm 下的 1.3 MPa。通过保水特性和 X 射线计算机断层扫描 (CT) 对土壤结构进行量化，作为评估土壤孔径分布和特性的补充方法。与均质土壤相比，1.55 g cm 时，异质土壤的大孔多出 50%。研究发现，异质结构中的孔结构复杂性有利于豌豆和大麦的根部生长，但对拟南芥没有帮助。与同质土壤相比，在 1.55 g cm 的异质土壤中生长的豌豆芽生物量增加了 65%，而大麦和拟南芥芽生物量在任何处理之间没有显着差异。由于芽的大小，叶绿素、类黄酮和氮含量只能在大麦或豌豆上测量，但土壤结构之间仅观察到微小差异。土壤结构异质性影响许多根系特性和地上生物量，其影响被发现与物种相关，并且可能是由根系大小和大孔优先生长之间的相互作用引起的。