Phytotoxicity of fuel to crop plants: influence of soil properties, fuel type, and plant tolerance.

The aim of the present study was to determine the effect of fuel-contaminated soils on the germination, survival, and early growth of six crop plants, viz.Brassicaoleracea,Trifolium repens,Lactuca sativa,Avena sativa,Pisum sativum, andZea mays, grown on Cambisol A and B horizons contaminated with gasoline and diesel (0%, 1.25%, 2.5%, 5%, and 10%, w/w). Fuel toxicity was more evident in the B horizon than in the A horizon, and diesel was more toxic than gasoline, probably due to the higher evaporation rate of the latter. Fuels affected the germination and survival of small-seeded plants to a higher extent, reflecting the importance of the seed coat and nutrient reserves for successful plant development in fuel-contaminated soils. In general, root growth was more strongly affected than shoot growth, and plant biomass was more strongly affected than elongation, leading to a less plant branching in the presence of fuel. The findings of this study can be useful for selecting the least fuel-tolerant species as soil contamination bioindicator and for determining the risks of fuel contamination. Due to the low residence time of gasoline components in soil, this phytotoxicity test resulted in an unsuitable bioassay to assess gasoline toxicity. [ABSTRACT FROM AUTHOR]