© 1989 Heron Publishing—Victoria, Canada
Temporal allocation of 14C to extramatrical hyphae of ectomycorrhizal ponderosa pine seedlings
Steven L. Miller (1, 2), Daniel M. Durall (1, 3) and Paul T. Rygiewicz (4)
1. Department of Forest Science, Oregon State University, Corvallis, OR 97331, USA / 2. Department of Botany, University of Wyoming, Laramie, WY 82071, USA / 3. Department of Plant Sciences, Oxford University, Oxford OX1 3RB, England / 4. Environmental Research Laboratory, U.S. Environmental Protection Agency, Corvallis, OR 97333, USA / Received July 6, 1988
Summary
Ponderosa pine seedlings were inoculated with Hebeloma crustuliniforme either in growth pouches before they were transplanted to root-mycocosms (P seedlings), or at the time of transfer to root-mycocosms
(V seedlings). Uninoculated seedlings served as controls (U seedlings). The use of root-mycocosms allowed examination of portions
of hyphae separate from roots and rooting substrate but still in symbiosis with the host. The results thus provided a quantitative
basis for estimating hyphal mass and carbon allocation to extramatrical hyphae. The amount of 14CO2 fixed after a 2-h exposure was greatest for P seedlings and least for uninoculated seedlings. Four and nine days after exposure,
14C content was greatest in uninoculated seedlings and least in inoculated seedlings. In isotope distribution and dry mass accumulation,
V seedlings were more similar to U than to P seedlings. Calculated on a dry weight basis, the allocation of isotope to mycelium
suggested that extramatrical hyphae of P seedlings were a stronger sink for carbon than extramatrical hyphae of V seedlings.
Differences in inoculation methods resulted in differences in carbon allocation and physiology of extramatrical hyphae that
could affect seedling establishment and survival. Seedlings inoculated by one method cannot serve as surrogates for mycorrhizal
seedlings produced by other inoculation techniques.
