Fig. 3. Relationship between squared Roger's distance (MRD²) and panmictic midparent heterosis (PMPH) for grain yield, plant height, and days to silking. Intrapool crosses within Heterotic Group A (filled squares) and Group B (filled triangles), interpool crosses between A and B (*), and miscellaneous (open diamonds) are shown. 1 = Pool24, 2 = Pop21, 3 = Pop22, 4 = Pop25, 5 = Pop29, 6 = Pop32, 7 = Pop43; r is the correlation coefficient and b the slope coefficient.