Every marketing agreement and order must provide for the establishment of a commodity board of not less than seven nor more than thirteen members and specify the exact number, qualification, nomination, election or appointment, term of office, powers, and all other matters pertaining to the board. The members of the board must be producers. The chairman of the commission or a member of the commission or department designated by the commission must be an ex officio member of each commodity board and has a vote as specified in the order or agreement.