Additive Genetic Variance

    Variety 2 always outperforms Variety 1 over the complete range of environmental conditions (e.g., nutrient-poor soil at EQ index = 40, or with added fertilizer at EQ = 90). The relative response is predictable from experiments in any environment.  Variety 2 may be described as "genetically superior" to Variety 1.

     Note however that there is considerable scatter about the means, and that
Variety 1 in a good environment outperforms Variety 2 in a poor environment, if the difference in EQ is 30 points or more.

Figure ©2002 by Griffiths et al.; all text material ©2014 by Steven M. Carr