Effects of varying PAHs-polluted soils on the morpho-anatomy and physiology of Bermuda grass

Abstract

ABSTRACT This study was conducted to show the effects of high PAH levels on the external and internal structures as well as the functioning of a Poaceae species – Bermuda grass – during phytoremediation process. Two modalities – Tn: unpolluted planted soil and Tp: polluted planted soil – are applied to the monoculture of Bermuda grass for pollution at 10%, 20%, and 30% (weight/weight) with fuel oil, and co-cropping with Goosegrass in soils polluted at 10%. Morphological results revealed that monoculture is better than co-cropping as the sociability of the two species is negatively affected by PAHs. Contrary to monoculture, in the co-cropping the relative growth rate of Bermuda grass morphological parameters is decreasing over time in Tp. For monoculture, the aboveground plant density of Bermuda grass in Tp is not significantly different to Tn, while its specific root length is higher in Tn than Tp. Anatomical and physiological analyses of Bermuda grass show that PAHs impacted the hydromineral nutrition of this species. In fact, the vascular bundles of the stems and roots of Bermuda grass were less numerous in Tp, and the chlorophyll synthesis was 50% inhibited. Despite the slower physiological processes of Bermuda grass in polluted soils, the phytotoxicity of very high PAH levels is not fatal to this species. Its development and evolution on soils highly polluted with PAHs and its phytoremediation potential (more than 95% for total petroleum hydrocarbons and up to 100% for chrysene) therefore recognize it as particularly suitable for hydrocarbon phytoremediation, with wide geographical application thanks to its cosmopolitan nature.