Hi there. In answer to your specific question about nutritional value - I do not know if veg grown under powerlines is less nutritional. I repsond to your email bacuase i've seen some neat photographs of a corn field with powerlines going above part of the field. The seed was all from the same stock - the farmer had selectively saved superior traits for 13 years i believe. The corn directly under the power lines was noticably smaller and weaker. The shape of the depression on the corn field was consistent with the magnetic field that would surround the wires - great stuff to see. Now, this farmer is a Biodynamic farmer and i'm not sure if he sells this affected corn or not. Sorry to be pretty useless, but thought this anecdote may help you, or at least entertain.