Mr Appleby, from Wellington, does not live in the Ikaroa-Rawhiti electorate. His party did not put forward a candidate for the 2011 general election.
"Seven candidates are contesting the seat and whilst it would be great to feature them all, this is technically and editorially not possible," said Mr Wilcox.
"It is very difficult to shoot a debate of seven people outside the studio, in the confines of the marae where the debate is being held and with the resources available.
"It would require three extra cameras along with associated operators, sound equipment, lighting etc.
"Editorially it would mean each candidate would get less than five minutes on-air, over the duration of the debate which is far from ideal."
This was "clearly communicated" to Mr Appleby. "It has nothing to do with the ethnicity or the policies of the candidates," he said
Native Affairs producer Annabelle Lee-Harris agreed Mr Appleby's exclusion had nothing to do with his ethnicity.
"The practicalities of production mean we can't possibly cover all seven candidates in the debate. As has been explained to Mr Appleby - the four candidates appearing in the debate have been determined by party and/or candidate polling in the previous election and their profile within the Maori community.
"Aotearoa Legalise Cannabis did not stand a candidate for Ikaroa-Rawhiti in the last election. And of the 18,732 party votes cast in Ikaroa-Rawhiti in the last election, only 267 went to the Aotearoa Legalise Cannabis party."