Catálogo de publicaciones - revistas

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Purpose</jats:title> <jats:p>The mechanical contribution of plant roots to the soil shear strength is commonly modelled using fibre bundle models (FBM), accounting for sequential breakage of roots. This study provides a generic framework, able to includes the many different existing approaches, to quantify the effect of various model assumptions.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>The framework uses (1) a single model parameter determining how load is shared between all roots, (2) a continuous power-law distribution of root area ratio over a range of root diameters, and (3) power-law relationships between root diameters and biomechanical properties. A new load sharing parameter, closely resembling how roots mobilise strength under landslide conditions, is proposed. Exact analytical solutions were found for the peak root reinforcement, thus eliminating the current need for iterative algorithms. Model assumptions and results were validated against existing biomechanical and root reinforcement data.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Root reinforcements proved very sensitive to the user-defined load sharing parameter. It is shown that the current method of discretising all roots in discrete diameter classes prior to reinforcement calculations leads to significant overestimations of reinforcement. Addition of a probabilistic distribution of root failure by means of Weibull survival functions, thus adding a second source of sequential mobilisation, further reduced predicted reinforcements, but only when the reduction due to load sharing was limited.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>The presented solutions greatly simplify root reinforcement calculations while maintaining analytical exactness as well as clarity in the assumptions made. The proposed standardisation of fibre bundle-type models will greatly aid comparison and exchange of data.</jats:p> </jats:sec>

<jats:title>Abstract</jats:title><jats:sec> <jats:title>Purpose</jats:title> <jats:p>Rhizodeposition shapes soil microbial communities that perform important processes such as soil C mineralization, but we have limited understanding of the plant genetic regions influencing soil microbes. Here, barley chromosome regions affecting soil microbial biomass-C (MBC), dissolved organic-C (DOC) and root biomass were characterised.</jats:p> </jats:sec><jats:sec> <jats:title>Methods</jats:title> <jats:p>A quantitative trait loci analysis approach was applied to identify barley chromosome regions affecting soil MBC, soil DOC and root biomass. This was done using barley Recombinant Chromosome Substitution Lines (RCSLs) developed with a wild accession (Caesarea 26-24) as a donor parent and an elite cultivar (Harrington) as recipient parent.</jats:p> </jats:sec><jats:sec> <jats:title>Results</jats:title> <jats:p>Significant differences in root-derived MBC and DOC and root biomass among these RCSLs were observed. Analysis of variance using single nucleotide polymorphisms genotype classes revealed 16 chromosome regions influencing root-derived MBC and DOC. Of these chromosome regions, five on chromosomes 2H, 3H and 7H were highly significant and two on chromosome 3H influenced both root-derived MBC and DOC. Potential candidate genes influencing root-derived MBC and DOC concentrations in soil were identified.</jats:p> </jats:sec><jats:sec> <jats:title>Conclusion</jats:title> <jats:p>The present findings provide new insights into the barley genetic influence on soil microbial communities. Further work to verify these barley chromosome regions and candidate genes could promote marker assisted selection and breeding of barley varieties that are able to more effectively shape soil microbes and soil processes via rhizodeposition, supporting sustainable crop production systems.</jats:p> </jats:sec>