Within one month of the end of harvesting operations in a tahsil, or as soon thereafter as may be, the collector shall prepare, in the prescribed manner, a return of market prices current at the harvest time of all food and non-food crops grown in such tahsil and the return so prepared shall be accepted for assessing the money value of the produce of a holding in cases triable under this Act:
     Provided that if, in any area, the Central Government has fixed any price for any agricultural produce such price shall be accepted for making such assessment.