The effect of microbial inoculation on plant productivity
Inoculation of leaf microbial inoculum reduced plant productivity while inoculation of soil microbial inoculum increased plant productivity (Table 1, Fig. 1). There was a significant interaction between soil and leaf microbial inoculum in affecting plant productivity (Table 1, F(2, 292) = 7.34, p < 0.001). Specifically, the negative effects of high-concentration leaf microbial inoculum on plant productivity became weak when soil microbes were inoculated, e.g. high-concentration leaf microbial inoculation decreased plant productivity by 27% with no soil inoculation but decreased productivity by only 3% with soil microbe inoculation (Fig. 1a). Conversely, the positive effect of soil microbes on productivity was only significant when leaf microbes were inoculated, e.g. soil microbe inoculation increased productivity by 26% when leaf inoculum was applied while decreased plant productivity by 5% when soil microbes were inoculated alone (Fig. 1b).