SPEAKER:              Bahman Shaffi
                      Idaho University
                      
TITLE:                "Statistical Analysis of
                      Genotype-By-Environment Interaction
                      Using the AMMI Model and Stability
                      Estimates"

                           ABSTRACT

     Understanding the implication of genotype-by-
environment (GE) interaction structure is an important
consideration in plant breeding programs. A significant GE
interaction for a quantitative trait such as yield can seriously
limit efforts in selecting superior genotypes for both new crop
introduction and improved cultivar development.  Traditional
statistical analyses of yield trials provide little or no insight
into the particular pattern or structure of the GE interaction.
The Additive Main Effects and Multiplicative Interaction
(AMMI) statistical model incorporates both additive and
multiplicative components of the two-way data structure
which can account more effectively for the underlying
interaction patterns.  Intergrating results obtained from
biplot graphic displays with those of genotypic stability
analysis enables clustering of genotypes based on similarity of
response and degree of stability in performance across
diverse environment.  The AMMI model is presented, and its
usage in diagnosing the GE interaction structure is discussed.
Tai's regression-based stability statistics are employed to
determine the stability of genotypes tested.  Empirical results
are demonstrated using data from a national winter rapeseed
variety trial.