Heritability with positive Interaction
2 consistently outperforms Variety 1 by more than
50% under poorer environmental conditions (e.g., nutrient-poor
soil at EQ = 50). Variety 1 outperforms Variety
2 only in a
much better environment (e.g., added fertilizer at EQ = 80).
In intermediate environments (EQ = 65 ~ 75), the two
varieties perform equally well, with considerable variance.
Although increased yield always occurs with increased
environmental quality, the differential response of the two
varieties is not
predictable from experiments in either extreme
environment separately. A naive conclusion is that Variety 2 is "better"
than Variety 1. However,
Variety 1 in a better environment (EQ=70) produces
the same yield (70) as Variety 2 in a poorer environment
(EQ=60). Choice of which variety to plant will depend
on a trade-off between the cost of environmental improvement
and the price of increased yield.
Figure ©2002 by Griffiths et al.; all text material ©2016 by
Steven M. Carr