why italians call maize as granoturco?

Answer 1

Granoturco and mais are the two more common name, in Italy.
"Mahiz" was the word used by people met by Colobo (Columbus) in Hispaniola.
Cultivation of maize begun in Europe during first half of 1500, especially in Andalusia, Spain, by Arabs (Moriscos, who stayed in Spain even after the end of Arab supremacy over Iberian peninsula).
But people became muddled up about the real origin of maize because of travelers who were impressed by huge farming in Persia, which was at the time under Turkish dominion. Hence the name.
Although in Italian the adjective "turco" was referring to everything exotic, in the past.

Answer 2

I'll tell you why. Back in 1645, my ancestor, don Julio Vasquez, was in ITALY helping the people construct roads. Well, one day these people showed up with what is known today as maize.The woman who was selling the maize,[ she was very elderly] would distribute the maize, my ancestor[ god bless him] called her granny. Hence the first 4 letters , gran. The word OTURCO came about when "ole Julio Vasquez [my ancestor] would always yell out that word when the factory that was processing turtles at the time needed more workers than they had. Then people would come and go to work. It was only natural that the two words would some day mesh together, seeing how they were being used at precisely the same time. My family has been responsible for many things in history, but I don't want to sound arrogant, so I remain silent!

Answer 3

Grannoturco is simply the Italian term for corn.
Nothing really more complicated or exotic than that.
Same as asking why Italians call tomatoes pomodori..