Dosage effects of the tb1-ref allele on root hair traits at 35 DAT. (A) Total root hair length per unit length of first order lateral roots. (B) Root hair initiation density per unit length of first order lateral roots. (C) Average root hair length. At 15 DAT, synchronously initiating crown roots were labelled (one per plant), and root hairs were scored 20 days later on lateral roots 5 cm away from the beginning of the branching zone on each crown root. Root hair traits were quantified using 192 digital images per genotype. Shown is the standard error of the mean estimate. Bars with the same letter are not significantly different at α = 0.05.