Dose-response analysis of diesel fuel phytotoxicity on selected plant species

[Graphical abstract presents]

As an ecotoxicological tool, bioassays are an effective screening tool to eliminate plants sensitive to the contaminant of interest, and thereby reduce the number of plant species requiring further study. We conducted a bioassay analysis of fifteen plant species to determine their tolerance to diesel fuel toxicity. Dose-response analysis revealed that increasing diesel fuel concentrations in the soil generally led to a monotonically decreasing biomass in 13 species (P < 0.001), with EC10 values (±SE) ranging from 0.36 ± 0.18 g/kg to 12.67 ± 2.13 g/kg. On the other hand, hydrocarbons had a statistically significant hormetic influence on Medicago sativa (f = 3.90 ± 1.08; P < 0.01). The EC10 and EC50 values (±SE) from the fitted hormetic model were 15.33 ± 1.47 g/kg and 26.89 ± 2.00 g/kg, respectively. While previous studies have shown M. sativa's tolerance of hydrocarbon toxicity, this is the first attempt to describe diesel fuel-induced hormesis in M. sativa using the Cedergreen-Ritz-Streibig model. This study thus shows that hormesis cannot be ignored in plant toxicology research, and that when present, an appropriate statistical model is necessary to avoid drawing wrong conclusions.