Influence of Rhizophagus irregularis inoculation and phosphorus application on growth and arsenic accumulation in maize (Zea mays L.) cultivated on an arsenic-contaminated soil.

Southern Tuscany (Italy) is characterized by exten- sive arsenic (As) anomalies, with concentrations of up to 2000 mg kg soil−1. Samples from the location of Scarlino, containing about 200 mg kg−1 of As, were used to study the influence of the inoculation of an arbuscular mycorrhizal (AM) fungus (Rhizophagus irregularis, previously known as Glomus intraradices) and of phosphorus (P) application, sep- arately and in combination, on As speciation in the rhizo- sphere of Zea mays on plant growth and As accumulation. Also, P distribution in plant parts was investigated. Each treatment produced a moderate rise of As(III) in the rhizo- sphere, increased As(III) and lowered As(V) concentration in shoots. P treatment, alone or in combination with AM, aug- mented the plant biomass. The treatments did not affect total As concentration in the shoots (with all the values <1 mg kg−1 dry weight), while in the roots it was lowered by P treatment alone. Such decrease was probably a consequence of the competition between P and As(V) for the same transport systems, interestingly nullified by the combination with AM treatment. P concentration was higher with AM only in both shoots and roots. Therefore, the obtained results can be ex- tremely encouraging for maize cultivation on a marginal land, like the one studied.