RELATION OF INTERNAL PHOSPHORUS CONCENTRATION AND PLANT WEIGHT IN PLANTS INFECTED BY VESICULAR‐ARBUSCULAR MYCORRHIZAS

S ummary Our own results and a search of the literature have shown that shoots of plants infected with vesicular‐arbuscular mycorrhiza normally contain higher internal concentrations of P than those of uninfected plants of equal size, over wide ranges of external P supply and of host plants. Increased demand for carbon by infected roots is a possible explanation for this, and simple graphical methods of estimating the resulting dry wt loss are suggested.