Fig. 3. Mean genetic improvement rates as influenced by plant population derived from a) 42 cultivars (Exp. 1), and b) seven soybean cultivars (Exp. 2) released from 1934 to 1993, from trials grown at Ottawa, ON. Standard errors of means for Exp. 1 in 1998 on clay loam and sandy loam are 2.5 and 2.4 and for 1999 on clay loam and sandy loam are 3.2 and 2.9; and for Exp. 2 for 1999 on clay loam and sandy loam are 4.3 and 4.1 and for 2000 on clay loam and sandy loam are 4.8 and 5.9, respectively.