CLASSIFICATION OF LOCATIONS IN REGIONAL COTTON VARIETY TRIALS WHERE TRIAL ENTRIES CHANGE OVER YEARS

Cultivars and advanced breeding lines evaluated for performance in reg ional trials usually change over successive years. Cluster analysis pr ocedures are presented for analysing these unbalanced genotype X locat ion X year data-sets to help study the effectiveness of locations to d iscriminate amongst genotypes (lines). To illustrate the use of these methods, yield data from 12 years of cotton evaluation trials conducte d at eleven locations in eastern Australia were analysed. The eleven l ocations were classified according to the way they discriminated among st lines. The combined classification analysis provides the plant bree der with a better understanding of the relationships amongst the locat ions used for regional cultivar trials and provides a rational method for choosing a few key locations to be used for early generation testi ng of lines from a breeding program.