There are many variables that are needed to answer that question. First, what are the loads on the decking (namely dead load and snow load)? Will the decking be spanning one bay at a time, or will it span multiple bays? What grade of pine is it? What kind of layup will be used (controlled random being a common one)?
Around here, with Doug-fir deck, 4'-0" is a common span, though you can go further depending on the variable mentioned above.
