TRANSLOCATION OF SOIL-DERIVED PHOSPHORUS IN MYCELIAL CORD SYSTEMS IN RELATION TO INOCULUM RESOURCE SIZE

Uptake of P-32 phosphorus from soil was investigated in mycelial cord systems of Phanerochaete velutina, Hypholoma fasciculare, Tricholomops is platyphylla and Phallus impudicus which extended from 0.5, 2, 4 or 8 cm(3) beech (Fagus sylvatica) inocula. Cord systems accumulated betw een 4.8 and 18.7% of phosphorus supplied to soil, according to species and size of inoculum. Phosphorus translocation to newly-colonized 2 c m(3) beech baits, determined non-destructively, was characterized by a n initial steady phase, of 2.5 to 32 nmol P day(-1) which lasted at le ast 12 days for all four species. After the initial steady phase, tran slocation rates declined. Initial mycelial extension and wood decay ra tes also varied with species and inoculum size. There was no dear rela tionship between phosphorus translocation rates, wood decay or the dis tribution of soil-derived phosphorus in cord system components. Howeve r, with increasing inoculum size, P. velutina systems allocated a sign ificantly greater proportion of available phosphorus to newly-colonize d baits. The degree to which distribution of soil-derived phosphorus i n cord systems is related to nutrient conservation or metabolic demand in the fungi is discussed.