<p>(<b>a</b>) Overall, maximum root length differed significantly depending on the neighbouring plant present in the sealed central box (n = 32 per treatment). Seedlings growing next to adult chilli plants had significantly shorter roots than those in the empty control or growing with the fennel (P = 0.015). (<b>b</b>) The presence of a neighbouring fennel during germination and emergence caused an increase in early root development of chilli seedlings when the communication channels are blocked, but not when unblocked (light grey bars) (F masked > F open and Control masked; P = 0.027; n = 80 per treatment). Differences disappeared when seedlings were allowed to grow away from a fennel plant (dark grey bars) (P = 0.94; n = 80 per treatment). Error bars indicate standard errors.</p
