XODI7IZD STABILITY ANALYSIS AD ON-FARM RESEARCH TO
BREED SPECIFIC ADAPTABILITY YOR ECOLOGICAL DIVERSITY
Peter Z. Hildebrand'
ABSTRACT
In this article, it is argued 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. These four factors are: 1) statistical dependence on ANOVA that leads to the concern with reducing genotype-by-environment interaction. This, in turn, leads to 2) the nearly universal practice of evaluating material on experiment stations and farms with real or artificially-created superior environments. Adding to the effect has been 3) the capability of many farmers in the developed world to use their resources to modify unfavorable environments. The final factor has been 4) the widespread use of a regression coefficient of unity as a measure of. stability when evaluating environmental effect on genotype. To enhance genetic diversity and to provide materials that excel in poor as well as favorable environments to help achieve a more sustainable agriculture worldwide, it will be necessary to 1) capitalize on genotype-by-environment interaction rather than depress it, 2) subject new materials as early in the development process as possible to poor as well as good farm conditions, and 3) search for materials with low and high
regression coefficients rather than suppressing them.
For more than half a century (Yates and Cochran, 1938), agricultural scientists, plant breeders in particular, have been using some form of stability analysis (Eberhart and Russell, 1966) to evaluate germplasm over different locations and environments. Seed companies have also used stability analysis in their breeding and evaluation work for a number of years (Bradley et al., 1988). Recently, persons in developing countries and working with farming systems research and extension methodologies (Hildebrand and Poey, 1985) have been using a modified form of the procedure to develop practices and germplasm for the widely varying environments found in many of these countries. While the works cited above use a common methodology to find superior technology, the reasons for its use, the philosophy behind it, and the results differ.
Over the last few decades, and in the developed world where resources were relatively abundant, widely adaptable technology, achieved by manipulation of the crop growing environment on farms, has been feasible. Mechanization, irrigation, and heavy use of
1 Food and Resource Economics Department, University of Florida, Gainesville, FL 32611.
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