Peculiarities of Higher Plant Response to Hydrocarbon Contamination in Sandy Soil Upon Phytotesting

Based on a model experiment involving hydrocarbon contamination of sandy soil, the response of higher plants to varying concentrations of the pollutant was studied during phytotesting. The experimental research aimed to assess the acute toxic effect and was conducted using the plate phytotesting method, with white mustard (Sinapis alba L.) as a dicotyledonous test crop and sweet sorghum (Sorghum saccharatum L.) as a monocotyledonous test crop. It was established that the plant response to hydrocarbon contamination (diesel fuel) in sandy soils is nonlinear, with a pronounced toxic effect at low concentrations (1–2 wt. %) and reduced toxicity in the range of 3–5 wt. %. It is hypothesized that this effect may be due to the organic nature of hydrocarbon contamination and the presence of available nutrients within the tolerance range of the higher plants used. These assumptions were supported by the results of assessing changes in the total microbial population in contaminated sandy soils during phytotesting, where an increase in the number of active microbial communities was observed at low diesel fuel concentrations (1–3 wt. %). The metabolic products of these microorganisms may have a pathogenic effect on the developing test crops. The identified patterns will further enhance the efficiency of the biological stage of reclamation carried out in areas with hydrocarbon-contaminated sandy soils.