FIGURE 4.

In situ and in vitro exudate metabolite profiles Principal component (PC) analysis of root exudate metabolite profiles collected in situ (a) or in vitro (b). Substrates are grouped as follows: beads big: 3‐mm and 2‐mm glass beads; beads small: 1‐mm and 0.5‐mm glass beads; sand big: 4‐mm and 250‐µm sand; sand small: 5‐µm sand. The small sand dataset is missing from the in vitro analysis due to a technical error. Control: exudates from hydroponics. PC analyses of single substrates and hierarchical clustering of the data are displayed in Figure S7