<p>Lengths are shown for the control, the different TiO<sub>2</sub> NP treatments in two concentrations 1 (low) and 2 (high) that are described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0155111#pone.0155111.t002" target="_blank">Table 2</a>, and the 16.1 mg l<sup>-1</sup> ZnSO<sub>4</sub> treatment (a) in presence of <i>R</i>. <i>trifolii</i> or (b) without <i>R</i>. <i>trifolii</i>. Significant (p<0.05) differences to the respective control (n = 6) are indicated with asterisks above the standard deviation error bars for shoots, and below the error bars for roots. The results of the same treatments with and without <i>R</i>. <i>trifolii</i> are not significantly different and neither were the controls, but the root length of ZnSO<sub>4</sub> with and without <i>R</i>. <i>trifolii</i> was different (p = 0.005).</p
