9. Ear parents of double crosses must grade well.
A high percentage of regular flat kernels is desired of a single cross used as a seed parent of a hybrid. This is so because it results in a larger amount of salable seed from a given acreage. Every extra bushel of salable hybrid seed corn produced per acre in Illinois represents an additional million dollars to our hybrid seed corn industry.
Extensive tests have been made in Illinois to locate better grading seed parents. Using a specially‑designed experimental grader, single cross parents were found to differ greatly. For example, 65 per cent of the seed of K201x38‑11 graded large flat or extra large flat compared to only 5 per cent of the same grades of K4x38‑11. Forty per cent of K4x38‑11 graded small flat compared to only 2 per cent of K201x38‑11. Also, K201x38‑11 had only one per cent cull corn while K4x38‑11 had 11 per cent of cull corn.
R. W. Jugenheimer