Fig. 3. Response of corn plants to removal of competition by thinning. Initial plant population of 40,000 per acre was decreased to 35,000 (by 12.5%), 30,000 (25%), 25,000 (37.5%), and 20,000 (50%) at stages indicated. Data are from a study conducted at Urbana, Illinois, 1995-96.

Image from Crop Management article:
Inter- and Intraplant Competition in Corn