Comparing Stability Indices for Ripening Date and Yield in Blueberry

To determine if any of the available techniques for estimating stability in different environments are useful in blueberry (Vaccinium ashei Reade and V. corymbosum L.), 14 clones were evaluated in nine environments for ripening date and yield. Type 1 and 2 stability statistics, plots for each genotype mean versus its coefficient of variation ( CV) across environments (genotype grouping), environmental index regression, and cluster analyses were compared. The highest yielding rabbiteye and southern highbush clones across locations were not deemed stable by Type 1 and Type 2 stability statistics, genotype grouping, or environmental regression technique. No evidence of curvilinear response was found. The nonparametric cluster analysis with known cultivars included appears to be most useful compared to other methods of estimating stability used in this study.