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Phytotechnologies for Site Remediation
a. Miscanthus root systems are large and well-developed, and plant
metabolism is vigorous. Also, carbon-containing compounds
released by plant roots supply the microorganisms located in rhizosphere (Rhizobacteria) with nutrients and organic acids (Hromádko
et al., 2014; Zgorelec et al., 2020). Such acids can suppress trace element toxicity. Guo et al. (2017) reported that under Cd stress M.
sacchariflorus roots secreted malate which mitigated Cd toxicity for
the plant, by reducing its absorption.
b. Antioxidant and photosynthetic activities of Miscanthus are well
developed. The antioxidant defense system plays a crucial role in plant
stress response. Along with the ability to mitigate stress-induced disturbances, it can serve as an indicator of trace element toxicity-induced
stress. An increase of malondialdehyde content reflects Cr stress (Jiang
et al., 2018). Significant increases in chlorophyll content, superoxide
dismutase, and peroxidase activities are observed in M. floridulus and
M. sacchariflorus growing in soil slightly contaminated by Pb, Zn, or
Cd (Zhang et al., 2015). M. × giganteus behavior was similar under Pb
and Zn stresses (Nurzhanova et al., 2019).
c. The Miscanthus rhizosphere contains many microbial colonies that
participate in plant–soil interaction (Wang et al., 2020). Schmidt et al.
(2018) reported that plant inoculation with bacteria and fungi isolated
from different Miscanthus species’ rhizospheres improved plant
growth. Firmin et al. (2015) obtained the same result after inoculating M. × giganteus by Funneliformis mosseae. Inoculation of Miscanthus
rhizomes with plant growth promoting bacteria increased the biomass
by ~77% after first vegetation season in postmining soil contaminated
by trace elements (Pidlisnyuk et al., 2020a; Pranaw et al., 2020).
2.5.2 Changes in Soil Parameters Induced by
Miscanthus Phytoremediation
Miscanthus planting in contaminated soils can increase soil carbon content, enhance aggregate stability, and improve water-holding capacity.
The improving effect of the plant on soil physiochemical properties is
mainly attributed to decomposition of underground organs and litter of root
residuals in soil (Wang et al., 2020). McCalmont et al. (2015) showed that the
decomposition of litter and underground organs of Miscanthus provides a
large amount of organic carbon to soil, which increases soil organic matter,
promotes soil nutrient cycling, improves the texture, structure, and waterholding soil capacity, and reduces soil nutrient loss.
Miscanthus was cultivated in marginal soil with the application of
soil amendments, biochar, and biosolid, that enhanced the abundance of
humus and mycorrhizal fungi, and improved soil fertility and hydraulic
properties. Biosolids exerted the most pronounced effect (Allami et al., 2019).