Root traits of different wheat cultivars influence soil structure: an X-ray computed 4 tomography and root morphology study

Plant roots play a fundamental role in maintaining soil health. Although a broad range of root traits 25 have been reported, few studies have attempted to link root morphology with soil structure. Here, we 26 used shovelomics to characterize the root morphology of a wheat cultivar (Paragon), and two 27 landraces (Senatore-Cappelli, and Watkins238), and advanced soil pore and root network X-ray 28 computed tomography to assess their impact on soil morphology at cylinder and aggregate scales. 29 Bare soil was analyzed as a control. Minkowski functionals and percolation theory parameters were 30 computed to characterize soil pore network morphology. Bioporosity at the cylinder scale was 31 significantly different for all cultivars compared to the bare soil. Bare soil presented the largest 32 structural pore volume and the smallest biopore volume, this suggesting rapid degradation of 33 biopores. At the cylinder scale, biopore characteristics were significantly different between Senatore34 Cappelli and Watkins238, with Senatore-Cappelli exhibiting more pores with diameters >1 mm. The 35 parameters from percolation theory revealed notable differences between the rhizospheric and bare 36 soil samples. We found significant differences between genotypes, finding statistically significant 37 correlations among root morphology parameters and pore network geometry. 38 Total imaged porosity and total root volume were limited descriptors of the effect of roots on soil 39 structure, which is better quantified by pore network connectivity measurements. Our findings 40 confirm previous studies on the relationship between root traits and soil properties and highlight the 41 potential of our experimental approach to explore how different genotypes may influence soil 42 morphology, paving the way for future applications in plant phenotyping