Representative root phenotypes of 14 Arabidopsis accessions on three hormone treatments and control.(a) One‐hundred and ninety‐two Arabidopsis accessions were grown on control conditions for 7 days followed by transfer to media supplemented with auxin (IAA), cytokinin (CK) and abscisic acid (ABA), or no hormone (C, control). Plates were scanned on day 10, and root traits were quantified and segmented using FIJI. Here, we show representative segmented seedlings of 14 accessions.(b) Broad sense heritability of all quantified root traits in all conditions.(c) Heatmap of (log2) fold‐change for each trait and hormone treatment compared with control treatment across all 192 accessions and four conditions. Ten root traits were quantified: primary root length (P), growth of P after the transfer (P2), branching zone (R), average lateral root length (LRL), lateral root numbers (LR.No), total lateral root length (TLRL), total root length (TRL), root density in P (LRD_P), root density in R (LRD_R), length ratio (LRR) (Figure S2b,c).