Nine members of the commission shall be producers who are citizens and residents of this state. Each producer member shall be over the age of twenty-five years and have been actively engaged in growing tree fruits in this state and deriving a substantial portion of his or her income therefrom, or having a substantial amount of orchard acreage devoted to tree fruit production or as an owner, lessee, partner or an employee or officer of a firm engaged in the production of tree fruit whose responsibility to such firm shall be primarily in the production of tree fruit. Such employee or officer of such firm shall be actually engaged in such duties relating to the production of tree fruit with such firm or any other such firm for a period of at least five years. The qualifications of the members of the commission set forth in this section shall continue during their term of office.