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 process, distribute, or handle within this state under a uniform rule, which is applicable to all handlers that are so regulated, which is based upon the quantities of such commodity, or of any grade, size, or quality of it, of the current season’s crop which each such handler has available for such processing, distribution, or handling, or upon the quantities of such commodity, or of any grade, size, or quality of it, which is so processed, distributed, or handled by each such handler in a prior period which the director finds to be representative, or based upon both, to the end that the total quantity of such commodity, or any grade, size, or quality of it, processed, distributed, or handled within this state during any specified period is equitably apportioned among all such handlers of the commodity.