Inflow of Phosphate Into Mycorrhizal and Non‐mycorrhizal Plants of Trifolium Subterraneum at Different Levels of Soil Phosphate

Summary During early growth of mycorrhizal and non‐mycorrhizal plants of Trifolium subterraneum fertilized with soluble (Na2HPO4) phosphate, inflow of phosphate (moles P absorbed per unit length root per unit time) into mycorrhizal roots from soil exceeded that into non‐mycorrhizal roots over a range of levels of phosphate. High rates of uptake (up to 45 × 10−15 mol phosphate cm−1 s−1) were associated with reductions in root: shoot dry wt ratios. The length of mycorrhizal root per plant was little affected by fertilization with phosphate. However, rapid growth of roots at high levels of Na2HPO4 resulted in reductions in percentage root length infected by mycorrhizas. Results are discussed with respect to rates of uptake by whole plants and to differences in distribution of phosphate between roots and shoots in mycorrhizal and non‐mycorrhizal plants.