Unexpected beneficial effects of arsenic on corn roots grown in culture

Corn (Zea mays) roots were grown in culture on modified Strullu-Roman medium in two separate experiments. Roots were exposed to one of four treatments combining arsenic (100μg L^-1 or 0.0μg L^-1) and phosphorous (4.8 mg L^-1 or 0.0 mg L^-1). The cultures were allowed to grow for 18 days or 21 days before they were used for quantitative measurement of root mass, root length, number of branches, and branch length. Results indicate roots grown in medium lacking phosphate but containing arsenic were longer and had greater mass than roots grown in medium with only phosphate. The data presented here suggest that arsenic at low levels might be beneficial for root development.