Effect of root hair length on white clover growth over a range of soil phosphorus levels

In an attempt to improve the competitiveness of white clover within swards on low‐phosphorus (P) soils, selections were made for plants with long or short root hairs within Trifolium repens L. cv. Tamar. Three populations with significantly different root hair lengths were grown at a range of soil‐P levels. Increasing root hair length has a significant effect on plant dry weight because of increased P absorption, if the roots were not mycorrhizal. However, mycorrhiza are ubiquitous in New Zealand pastures and therefore increases in root hair length may not improve white clover performance on low‐P soils.