A marketing order may contain provisions for allotting the quantity of any commodity, or of any grade, size, or quality of it, which each handler may purchase or acquire from, or handle on behalf of, any and all producers of the commodity, within this state during any specified period under a uniform rule, which is applicable to all handlers that are so regulated based upon the amounts produced or sold by such producers in a prior period which the director finds to be representative, or upon the current season’s production or sales of such producers, or both, to the end that the total quantity of such commodity, or of any grade, size, or quality of it, which is so purchased or handled within this state is apportioned equitably among the producers of the commodity.