Germination and early seedling development of Helichrysum microphyllum Cambess. subsp. tyrrhenicum Bacch., Brullo & Giusso in the presence of arsenates and arsenites

Arsenate, As(V), and arsenite, As(III), are the most available arsenicals present in the soil solutions, in particular in mine polluted substrates, and cause several symptoms of toxicity in plants (like inhibition of seed germination and reduction of seedling development). For these reasons, seeds germination studies are essential for the design of phytoremediation activities of mine sites. Seed germination and seedling development of Helichrysum microphyllum subsp. tyrrhenicum, were evaluated at 15 °C using various concentrations of As(V) and As(III) (0-500 mg/L and 0-200 mg/L, respectively). Seeds were harvested (I) into a mine dump contaminated in As, (II) nearby this site, and (III) faraway the As contaminated area and without mine activities. Seed germination, cotyledons emergence, and seedling mortality were evaluated for 90 days. As(V) and As(III) acted differently, showing a much higher toxicity when arsenite was added than arsenate. The taxon was able to germinate, develop cotyledons, and survive under all arsenate concentrations, whereas arsenite acted on these steps already at 2.5 mg/L. Moreover, a linear decrease in cotyledons emergence was assessed with the increase of both arsenicals' concentrations, as well as a linear decrease of seedling survival under arsenite. The taxon showed great adaptability to As pollution, giving an important contribution in phytoremediation of mining sites.