Influence of Root Hairs in Supplying Soil Phosphorus to Wheat

Chromosome substitution lines of wheat (Triticum aestivum L.) showing a parental difference in root-hair development were studied under several P regimes. Average root-hair density was 45 root hairs/mm in a low-P soil compared with 60 when P supply was adequate. Soil P uptake was not closely related to root-hair density in any of the regimes. Rape roots virtually devoid of root hairs took up two to six times as much soil P per unit length as the wheat roots with root hairs. Flax roots also did not produce root hairs but absorbed more P per unit length than the wheat roots. Root-hair development did not regulate the P uptake efficiency of the wheat roots and would be expected to be even less effective in supplying other nutrients.