“Grower-handler” means any person who is engaged within the state in the business of producing or causing to be produced, through contractual agreements or other legal relationships and having an ownership therein, iceberg lettuce, and who in addition thereto prepares for market and markets, either through its own sales force or by agents or contract sellers, 250,000 pounds or more of such lettuce during a marketing season and who is not a secondary handler, as defined in Section 66542.5. Any producer who for his own account engages the services of another person to prepare for market and markets 250,000 pounds or more of his own production during a marketing season, shall be deemed the handler thereof. In determining whether the grower-handler has marketed 250,000 pounds or more of lettuce during a marketing season, there shall be excluded from such computations all shipments of 200 pounds or less of iceberg lettuce sold or shipped by a handler directly to the consumer.