INVESTIGATION OF YIELD AND PERSISTENCE OF WHITE CLOVER USING CLUSTER ANALYSES

A visual growth score method was used to monitor the growth performanc e of 24 populations of white clover (Trifolium repens) over a three ye ar period. The mean growth scores for each year were used as populatio n x year data for cluster analyses. Cluster analysis methods based on a regression model where genotypes were grouped for similarity of both intercepts and slopes (Method 1) or slopes only (Method 2), were able to differentiate the persistent populations from those that showed a yield decline over time. The deviations from regression mean square wa s used as an indication of stability. Method 1 was able to cluster the high yielding persistent populations into a separate cluster, thus fa cilitating the selection of desirable populations. Deviations from reg ression identified the stable populations from the cluster. In combina tion with the simple growth score system, this analytical method is a powerful tool for evaluating a large number of breeding families of pe rennial pasture clovers and grasses for yield and persistence.