FORAGE SORGHUM IN SOUTHERN MANITOBA

After a series of hot, dry years in the late 1980s a study was conduct ed to assess the suitability and yield stability of forage sorghum (So rghum bicolor L. Moench.) in southern Manitoba. The effects of genotyp e and environment on DM yield of seven forage sorghum genotypes were e valuated (1990-1992) in six different environments. Genotype, environm ent and genotype x environment accounted for 3.9% (P < 0.0001), 84.8% (P < 0.0001) and 3.3% (P < 0.001) of the total variation in DM yield, respectively. The fact that environment accounted for most of the vari ability in DM yield and that relative rankings of varieties differed a cross environments indicated that yield was unstable. Forage sorghum p roduced acceptable DM yield only in years which were warmer (> 2700 CH U) than average (2200-2600 CHU) for southern Manitoba. Forage sorghum is not recommended for southern Manitoba unless the climate warms to w here 2700 CHU are consistently accumulated during the growing season.