Figure 1.

Effect (Cohen’s d) of applying different classes of PGPs (general, animal-derived, seaweed-based) as a root drench on plant shoot growth when plants were grown in a low nutrient potting mix. (a) Cohen’s d obtained in 148 trials; (b) weighted mean effects (± 95% CI) for each product estimated using REML analysis. Positive effects represent situations where the PGP caused an increase in shoot growth compared to plants treated only with water. See Supplementary File S1 for results of each individual trial. For product codes see Table 1.