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Figure 4: Predicted smoothed PSA for all 8 combinations of Mycorrhiza and Zinc in barley (a), tomato (b), and all 12 combinations in Medicago (c) inoculated with the AMF R. irregularis (blue) or mock-inoculated (red) and grown at four (a, b) or six (c) different soil Zn concentrations ranging from no addition of Zn (Zn 0) to high soil Zn addition, at four or five time points during growing. These predictions are based on the full interaction model, notwithstanding the fact that interaction fails to be statistically significant for barley at any time point. Error bars for barley are 95% confidence intervals. Error bars for tomato and Medicago are half of the least significant difference (LSD), meaning that two predictions are significantly different if and only if their error bars do not overlap.