Germination and seedling growth of the Chilean native grass Polypogon australis in soil polluted with diesel oil

The purpose of this study was to evaluate the ability of Polypogon australis, a Chilean native grass that colonizes copper polluted sites, to germinate and grow in soil contaminated with diesel oil. The effect of increasing proportions of diesel in soil (0.5%, 1%, 2%, and 5%) on the cumulative germination and growth of plants was measured. The relative seed germination (RSG), relative root growth (RRG), germination index (GI), and the effective concentration (EC₅₀) were calculated. The cumulative germination in soil polluted with 0%, 0.5%, 1%, and 2% of diesel oil in soil was 93.3%, 85.5%, 99%, and 78.5%, respectively, showing no significant differences between the treatments (p > 0.05). A proportion of 5% of diesel in the soil reduced the germination of P. australis by 50%, compared to the control. The growth of leaves and roots of the plants germinated in 5% of diesel was reduced by 30% compared to the control, with a 34% survival rate observed on day 40. The calculated EC₅₀ of diesel for P. australis was 4.5%. P. australis germinated and grew on all diesel concentration used in the experiments. The species was classified as a tolerant to diesel oil.

Growth, nutrient status, and photosynthetic response to diesel-contaminated soil of a cordgrass, Spartina argentinensis

The present study was conduced to investigate the tolerance limits of Spartina argentinensis, which occurs in inland marshes of the Chaco-Pampean regions of Argentina, to diesel-contaminated soil. A glasshouse experiment was designed to investigate the effect of diesel fuel from 0% to 3% on growth and photosynthetic apparatus of S. densiflora by measuring gas exchange and photosynthetic pigments. We also performed chemical analysis of plant samples, and determined mycorrhizal index. Tiller and root biomasses declined with increasing diesel fuel concentration, as well as photosynthetic rate (A). Reductions in A could be accounted for by non-stomatal limitations. Mycorrhizal roots of S. argentinensis were reduced by the presence of diesel fuel, but did not affect its nutritional status; in fact, most element concentrations increased with diesel contamination. Despite the negative effect of diesel-contaminated soil, S. argentinensis continued growing, which could be useful management options for phytorremediation of diesel-contaminated soils.