The referendum must be upon the question of whether or not the farmers eligible for participation and voting in the referendum shall vote upon themselves, for the period of three years, an assessment not to exceed ten dollars an acre on all tobacco acreage in the State, or not to exceed fifty cents for each hundred pounds of the flue-cured tobacco marketed by each farmer under the alternate method for assessment provided for in § 46-31-140, for the purpose of providing farmer participation in the fund and through the agency established for the promotion of flue-cured tobacco, the exact amount an acre of the assessment to be determined by the members of the board of directors of Tobacco Associates, Incorporated, subject to the approval of the majority of the South Carolina members of the board of directors.