Fig. 1. Plant spacing and emergence treatments are composed of repeatable sequences and each sequence unit consists of six maize plants: C, plant-emergence control; 2L, two-leaf emergence delay for plant in Position 3; 4L, four-leaf emergence delay for plant in Position 3; 20, plants spaced uniformly at 20-cm intervals (plant-spacing control); 40, 40-cm gap between plants in Positions 2 and Position 4, and double plants at Position 4; 60, 60-cm gap between plants in Position 2 and Position 5, and triple plants at Position 5. Plant positions from Position 1 to Position 6 are indicated under diagram (adapted from Liu et al., 2004a).