The effect of P deficiency on root morphology. A, Seedlings subjected to differing P supplies. B, Total root length. C, PR length consisting of the BZPR (darker gray) and LR FZPR (lighter gray). D, 1° LR density. E, Average 1° LR length. F, 2° LR density. G, Average 2° LR length. The numbers within the LR FZPR bar of C indicate the length of the LR FZPR as a percentage of the total PR length. Seedlings were cultivated for 5 d with no P added and then grown on the P treatments indicated for a further 13 d. Bars show means ± se (n = 21–29). [See online article for color version of this figure.]