"sale in sealed containers" means any sale of prescribed seed in containers sealed for the purposes of sale and sold at a price stated and fixed for each container of equal weight, quantity or volume, or any multiple thereof; or any such sale where each container is expressed to contain a specific weight, quantity or volume of seed and the price is calculated on the basis of such weight, quantity or volume, as the case may be; "sealed container" means any sack, bag, barrel, box, package, carton, envelope or other receptacle which is closed by means of sewing, stitching, stapling, nailing, heat sealing, gumming or glueing; "seed" means the part of any plant, customarily referred to as seed, intended for planting and includes seed potatoes; "seed cleaner" means any person engaged in the trade or business of eliminating impurities from seed; "seed cleaning plant" means any premises used for the elimination of impurities from seed; "seed importer" means any person who, either exclusively or in conjunction with any other trade or business, imports seed into Zambia for re-sale; "seed producer" means any person who, either exclusively or in conjunction with any other trade or business, produces seed for sale; "seed seller" means any person who, either exclusively or in conjunction with any other trade or business, sells seed for sowing; "seed-testing station" means any premises, suitably equipped therefor, where seed is tested for its purity and germination capacity; "sell" includes to exchange or barter or to offer, advertise, keep, expose, transmit, convey or delivery for or in pursuance of a sale, exchange or barter, and cognate words shall be construed accordingly; "specified variety" means any variety of prescribed seed which has been specified by the Minister pursuant to section forty-nine for the purposes of Part VIII;