Effect of Population and Row Spacing on the Performance of Four Corn (Zea mays L.) Hybrids¹

Four early corn hybrids were grown at the four populations of 30,000, 45,000, 60,000, and 75,000 plants per hectare, at each of the four spacings of 50, 65, 80, and 95 cm between rows. The row spacings did not affect grain yield. However, each increase in population produced a substantial increase in grain yield. Varieties differed significantly in their yield response to increased plant populations. The later maturing, taller hybrids were adapted better to the competition in high populations than were the earlier hybrids.