There is an excellent book on food plants cultivated by Incas:
Lost crops of the Incas : little-known plants of the Andes with
promise for worldwide cultivation / report of an ad hoc panel
of the Advisory Committee on Technology Innovation, Board on
Science and Technology for... Washington, D.C. : National
Academy Press, 1989.
I hope you can find it in a library.
aceska at freenet.victoria.bc.ca