Fig. 3.

Root length of Arabidopsis increased in response to increasing protein levels in growth medium. Bars represent averages and SD of two to four plates with ≈20 Arabidopsis plants per plate. Treatments included no nitrogen added to growth medium, protein added (0.3–12 mg BSA per ml), or inorganic nitrogen (0.4 mg NH₄NO₃ per ml). Different letters indicate significant differences at P < 0.001 (ANOVA, Neuman–Keuls post hoc test).