Repeatability of some statistical measures of phenotypic stability. Correlations between single year results and multi years results

The objective of this study- was to evaluate whether different statistical measures of phenotypic stability vary in their repeatability. Eight multi year and multi location variety tests of wheat, barley and oat were analysed separately for each year. Single year data of yield, of response parameters: environmental variance (S23 and coefficient of regression (b), and of stability parameters: deviation mean squares (S23), coefficient of determination (r2), ecovalence (W), and the nor, parametric measure variance of ranks (Si4), were correlated with multi year, multi location results. Repeatability of single year results was highest for yield, where rank correlation coefficients amounted to about 0.80. s2x and b showed medium values of nearly 0.55 The stability parameters s2d, r2, W and Si4 did not differ in their repeatability. Respective correlation coefficients possessed values of approximately 0.40 and were very variable from experiment to experiment. Reliability of single year results was especially low for experiments with high varieties × years interactions. Single year results of the examined variety tests could not serve as a basis to quantify phenotypic stability even if more than ten locations were involved.