At the same time, Finlay and Wilkinson were cognizant of the hazard resulting from discarding potentially valuable materials when searching for varieties with high mean yields over all environments.
Eberhart and Russell (1966), authors of probably the most cited article regarding the use of stability parameters, were concerned that large genotype-by-environment interactions reduced "progress" from selection. One means of reducing this interaction, they reported, is to stratify environments to make them more similar. However, they thought the resulting interaction still "frequently remains too large" (p.36). Their solution was a method to select stable genotypes that interact less with the environments in which they are grown and then use only the more stable genotypes for the final stages of testing. They then set their task in the article as finding the criteria necessary to rank varieties by stability. Ultimately they define a stable variety as one with an average response to environment (b-l), or what Finlay and Wilkinson called average stability, and a minimum of deviations from
regression where Sd2 0), or nearly so (p. 38).
ZT72CT ON PLANT T!CXNOLOGY DEVELOPMENT
Hypothesis
The hypothesis to be explored here is that the cumulative effect of four factors has led to at least a quarter century of rejecting genetic material that would have demonstrated superior yield capability in the best or the poorest farm environments and has not necessarily led to varieties or hybrids with superior yield capability in average environments. The four factors are:
1. statistical dependence on ANOVA that leads to the concern with reducing genotype by environment
interaction, which, in turn, leads to
2. the nearly universal practice of evaluating material on experiment stations and farms with real or artificially-created superior environments to control this interaction or to permit the material to manifest
its yield potential;
3. the capability of many farmers in the developed world, over the last few decades, to use their resources
to modify unfavorable environments; and
4. widespread use of a regression coefficient of unity
as a measure of stability
If progress from selection has been slow, it was the result of these factors, not the presence of genotype-by-environment interaction, which Eberhart and Russell considered to have a negative impact. If the present argument is convincing, then it could be concluded that genotype-by-environment interaction should be viewed as positive. Furthermore, the philosophy toward the use
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