is the size of the fruiting bodies of mycorrhizal fungi such as truffles proportionate to the size of the host tree?

I think it's very unlikely to be related. Truffle farming is a rather unusual case, but most mycorrhizal fungi (e.g. pretty much all the mushrooms you've ever seen on the ground) will be interacting with the roots of many plants simultaneously, with their mycelium network covering a very large area. This is different with some truffles which require specific host species, because if you are outside the natural range of the those species you might have to plant the host tree yourself. In that case there would be a limited supply of carbon to the fungus (but I still don't think it would affect fruiting body size).

 

Generally the range of sizes of a fruiting body is genetically determined, with environmental factors impacting the size within the range. It would be more likely that a small available carbon pool would lead to fewer fruiting bodies being produced (because the fungus would cover a smaller area).

Edited March 7, 201114 yr by Blahah