If it appears from an investigation that the revenue from the assessment levied under this act is inadequate to accomplish the purposes of this act, the commission shall file with the director of the department of agriculture a report showing the necessity of the industry, extent and probable cost of the required research, market promotion and advertising, extent of public convenience, interest and necessity, and probable revenue from the assessment desired to be levied. It may thereupon increase the assessment to a sum not to exceed one-half cent (1/2¢) per pound of clean seed; but no increase shall be made prior to filing of said report and favorable finding.