Structure of the soil pore space in the seedling bed before the seedling stage: studies using the microtomography method

In this paper we present a sequential observation of the barley seed root system germination at early development stages. A target of research was a two-layer seedbed model. The model is constituted by the topsoil material from soddy-podzolic soils (Albic Glossic Retisols (Lomic, Cutanic)). The material contains two differently structured layers of seedbed: the over-seed layer (loose; 40% of the total pore volume-pore diameter 0.5–1.5 mm) and the subseed layer (compacted; fine-pored layer is dominated by soil pore diameter of 0.01–0.2 mm). Control of the root system development was sequentially conducted with the benefit of nondestructive testing (computed tomography), which bring an opportunity to receive detailed images of roots development with an accuracy up to 16 µm. The study found that during 7 days after planting the seed emerging root system doesn’t depend on soil pore space structure surrounding the seed. The fact of a significant excess of the root diameter is noted in comparison with the diameters of soil pores, which indicates the ability of roots to push soil particles apart. It leads to an active pore space (pores-channels) formation.