Fig. 6.

Effect of homogeneous and heterogeneous Pi supply on (A) total root length, (B) length of first-order LRs, (C) first-order LR density, (D) first-order LR primordium density, (E) second-order LR number and (F) second-order LR length of maize plants pre-cultured with the auxin polar transport inhibitor NPA for 2 d but subsequently grown in the absence of NPA for 6 d. For explanation of treatments see the legend of Fig. 2. Bars indicate means ± s.e. (n = 6 individual plants). Different letters indicate significant differences among treatments (P < 0.05).