Degree Type


Date of Award


Degree Name

Doctor of Philosophy




The performance of 23 varieties evaluated in 92 environments was used to determine the relative importance of genotype x environment interactions, the relationship between environments and groups of environments, the relationship between varieties, and the response of the 23 varieties across environments in Bajio, Mexico. The experiments were conducted under rainfall and irrigation conditions at experiment stations and on farmers' land;The variance component estimates revealed that the variety x location and variety x location x year interactions were more important than the variety x year interaction. Cluster and principal components analyses indicated most of the variation and the relationship among environments were explained by moisture availability. The differences among varieties and their responses to environments were explained primarily by their relative maturities, their original germplasm sources, and their kinships. The residual data (variety x environment interaction values) were more efficient than mean data to differentiate relationship between varieties. The correlations and covariances between environments suggested that some environments, experiment stations, and states would be more appropriate for the development of varieties for the Bajio region;The stability analysis was calculated for each variety across all, random (years), and restricted (good and poor) environments. The stability of the varieties seemingly was influenced by maturity, source of germplasm, and selection history. Correlations of the stability parameters estimates showed that the mean and the coefficient of regression were significantly correlated and repeatable over environments. The information derived from the study was used to make some recommendations regarding variety development and testing in the Bajio region of Mexico.



Digital Repository @ Iowa State University,

Copyright Owner

José Ron-Para



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190 pages