Here is another comment on my posting a while back about how a dwarfing root stock will cripple a tree and cause it to be more susceptible to diseases. The next time a nurseryman tells you that the smaller tree will produce just as much fruit as a full size tree put on your best stupid face and ask him or her where does it get the extra energy?
Really! Has the tree perfected the perpetual motion machine? –Coldfusion? –Some other form of hidden energy? The smaller tree has fewer leaves, a smaller profile, and even a lower efficiency of light reception (the shade underneath it is less dense).
What is producing all that extra sugar to make the same amount of fruit?