Miscanthus × giganteus (M. × giganteus) is a perspective plant produced on marginal and contaminated lands with biomass used for energy or bioproducts. In the current study, M. × giganteus development was tested in the diesel-contaminated soils (ranged from 250 mg kg⁻¹ to 5000 mg kg⁻¹) and the growth dynamic, leaves quantity, plants total area, number of harvested stems and leaves, SPAD and NPQt parameters were evaluated. Results showed a remarkable M. × giganteus growth in a selected interval of diesel-contaminated soil with sufficient harvested biomass. The amendment of soil by biochar 1 (produced from wastewater sludge) and biochar 2 (produced from a mixture of wood waste and biohumus) improved the crop’s morphological and physiological parameters. Biochar 1 stimulated the increase of the stems’ biomass, while biochar 2 increased the leaves biomass. The plants growing in the uncontaminated soil decreased the content of NO₃, pH (KCl), P₂O₅ and increased the content of NH₄. Photosynthesis parameters showed that incorporating biochar 1 and biochar 2 to the diesel-contaminated soil prolonged the plants’ vegetation, which was more potent for biochar 1. M. × giganteus utilization united with biochar amendment can be recommended to remediate diesel-contaminated land in concentration range 250–5000 mg kg⁻¹.

The phytoremediation of industrial crops is becoming popular for the revitalization of land contaminated by trace elements (TEs). This approach combines biomass production with the improvement of soil health. To implement phytoremediation and derive sufficient dry biomass, crop production must be adequately supported by agricultural practices, including the application of bioinoculants. The current study aims to test the influence of several plant growth-promoting bacteria (PGPB), isolated from TEs-contaminated soil—i.e., Stenotrophomonas maltophilia KP-13, Bacillus altitudinis KP-14, and Pseudomonas fluorescens KP-16 and their consortia on the phytoremediation of the industrial crop M. × giganteus cultivated in the same TEs-contaminated soil. Contrary to expectations, the effects of PGPB on the biomass harvest were low. The most significant increase was detected in leaf biomass treated with a consortium of tested PGPBs. More significant effects were detected in the uptake of individual TEs. The phytoparameters of translocation factor, comprehensive bioconcentration index and uptake index were used to characterize the behavior of the TEs; Cr; Mn; Ni; Cu; Zn; Sr; V; and Pb in the presence of isolates. Plants treated with PGPB strains accumulated minimal concentrations of Cu and Pb in their aboveground biomass, while a tendency for Zn accumulation in the leaves and stems, and Sr accumulation in the leaves was observed. The obtained results reveal the combinations of isolates that lead to the minimal uptake of TEs into the stems and the simultaneous increase in DW. This study provides more insight into the leading factors of phytoremediation supported by PGPB and can be helpful when M. × giganteus is grown on TEs-contaminated soils of different origins.

The short-term effects of soil amendments on the structure, diversity and function of a nematode community of Miscanthus × giganteus was investigated. Crop was cultivated on marginal, nutrient-poor land amended with biochar in single and double doses (BD1 and BD2), biogas digestate (D), sewage sludge (SS), and hemicellulose waste (HW). Sampling was done after planting, in the middle and end of vegetation; morphology-based approach was used. 28 nematode taxa were identified, including 5 bacterivores genera, 4 fungivores genera, 5 herbivores genera (11 species), 2 omnivores genera, 5 predators genera. The general linear models, correspondence analysis and clustering were applied for evaluation. The total abundance of nematode taxa Filenchus, Dorylaimus, Cephalobus, Panagrolaimus, Aphelenchus, and Ditylenchus was depended on the sampling time and amendments. The incorporation of amendments affected nematode food web and resulted in suppression of plant-parasitic nematodes (PPNs). It was revealed that community structure was more mature for SS, less stable for D and had inconclusive effects for BD1, BD2, and HW. Using amendments ensured pest control benefits which is important given concern that PPNs can inflict crop damage during increased cultivation of M × g. Further research is needed to examine amendments which can minimise PPNs without reducing populations of nitrogen-fixing bacterivores and fungivores.