Scheffe-Caliriski and Shukla Models: Their Interpretation and Usefulness in Stability and Adaptation Analyses

In this paper, we compared the theoretical aspects and applications of two-way mixed models, viz., Scheffe-Calhiski's (S-C) model and Shukia's (Sh) model. Both models were considered in their basic form and as multiplicative, joint regression models. Despite the different observed covariance matrices in pairs of both basic and regression models, they adequately described performance (stability) of genotypes in randomly chosen environments. The statistical tools (estimators and tests) developed in the respective models (both basic and joint regression) are optimal or have desirable properties. The models may be regarded as pairs of alternative, realistic, and of similar statistical and practical efficiency, approaches to analyzing genotype means (across environments) and phenotypic stability of two-way data. (C) 2005 by The Haworth Press, Inc. All rights reserved.