Fig. 2. Dendrogram for clustering 34 sites used for testing field pea varieties in 1997 through 2001. The numbers in parenthesis after site names identify different geographic regions (cf. Fig. 1): 1d, South Alberta (dryland); 1i, South Alberta (irrigated); 2, East Central Alberta; 3, West Central Alberta; and 4, Peace River Region. The dashed line is the cutoff point for identifying isoyield groups. The regression lines of sites within an isoyield group do not differ significantly at the 0.05 probability level.