Fig. 2. Fitting Model 1 and Model 2 to the generation means in each B104 testcross progeny set. Testcross grain yield (Mg ha^-1) is plotted against the percentage of Parent 1 in the cross. Figure captions are in the form: (P₁ x P₂) * tester. Solid squares = observed grain yield with 95% confidence intervals; dashed line = Model 1 (linkage—no epistasis); solid line = Model 2 (epistasis—no linkage).