Fig. 2
From: Effect of nanoparticles on red clover and its symbiotic microorganisms
Biological nitrogen fixation. Percentage of atmospheric nitrogen derived from biological nitrogen fixation in red clover shoots for the control, P25 and NNM-TiO2, MWCNTs, CeO2 NPs, and ZnSO4·7H2O. The number behind the treatment name is the nominal concentration in mg kg−1. Rye grass was used as non-nitrogen fixing plant and the B value was assumed to be zero (see text). Error bars show the standard deviations (n = 7). Capital letters show significant differences compared to the control plants (p ≤ 0.05)