No relationship between leaf size and yield in medium leaf size white clover varieties under rotational sheep grazing and cutting

Nine medium leaf size varieties of white clover (Trifolium repens L.) were grown in field plots with perennial ryegrass (Lolium perenne L.) variety Fennema, and yield measurements were taken under both cutting and rotational sheep grazing. The sampling and management protocols in the cut plots mirrored those for the National List testing of white clover varieties in the UK. Dry-matter yields of the white clover and perennial ryegrass components of the mixture were recorded for six cuts in each of three harvest years. White clover yields were highest under cutting, perennial ryegrass yields under grazing. Significant differences were seen between the yields of white clover varieties, and significant interactions between white clover yields and management type were also observed. This interaction effect was not seen with respect to perennial ryegrass yields. No correlation was observed between leaf size and white clover dry-matter yield under either management type. The results suggest that leaf size, on the scale of variation represented within a leaf size category, is not a good predictor of yield under rotational sheep grazing or cutting. The significance of these results for varietal evaluation and for ascertaining the underlying bases for yield differences is discussed.