Grades and Requirements for Sweet Corn Application 138. The grade and the requirements set out in sections 139 and 140 apply to sweet corn varieties grown from Zea mays var. rugosa. Grade and Grade Name 139. The grade and grade name for sweet corn is Canada No. 1. Canada No. 1 Grade Requirements 140. (1) Subject to the general tolerances set out in section 141, sweet corn graded Canada No. 1 must • (a) be properly packaged; • (b) have similar varietal characteristics; • (c) be well co...