Phytoremediation Investigating Herbaceous Plants and Their Rhizosphere Microorganisms in the Mixture of Wood Sawdust of Used Sleepers and Soil Fertilised with Nitrogen

The studies were carried out in the period of 2013-2014 in an ex situ experiment developed during plant vegetation, cultivating 5 plant species in vegetative pots with a substrate contaminated with used sleepers and an uncontaminated substrate fertilised by nitrogenous fertilisers. The objective of the research was to analyse the morphological features of aboveground and underground parts of herbaceous plants and determine the dependence between the number of fungi and bacteria colonies in the rhizosphere of these plants and substrate contaminants and the impact of nitrogenous fertiliser concentration; with reference to that, to determine the feasibility of these plants for phytoremediation. A tolerant plant, i.e., Tagetes patula L. as a phytoremediator, which adapted to grow in the condition of a contaminated substrate fertilised by nitrogen and suitable for cultivating it in similar edaphic conditions, was used. An intolerant plant, i.e., Trifolium repens L. as a phytoindicator, is a perennial, herbaceous plant of Fabaceae Lindl. family, the rhizosphere of which contains the maximum number of fungi and bacteria colonies in the occurrence of the maximum concentration of nitrogenous fertilisers and contaminants. These bacteriological and mycological processes, as well as the excess of nitrogen, have a negative impact on the growth of aboveground and underground parts of Trifolium repens.