RESPONSE TO DIVERGENT SELECTION FOR STOLON CHARACTERS IN WHITE CLOVER(TRIFOLIUM-REPENS)

Stolen death, often caused by grazing or winter-kill, is a major facto r determining the survival and persistence of white clover (Trifolium repens L.), the most important forage legume in UK agriculture. Since stolen morphology apparently affects stolen survival, this study was d esigned to assess the genetic variation for stolen characters within a white clover population from Switzerland and to assess the effects of two generations of selection for stolen characteristics on that popul ation. Bidirectional selection was carried out simultaneously for stol en diameter (as the primary criterion of selection) and total stolen l ength i.e. the product of the length of the longest stolen and stolen number. Four selection lines were established: (a) plants with thick s parse stolons, (b) plants with thick profuse stolons, (c) plants with thin sparse stolons and (d) plants with thin profuse stolons. Realised heritabilities for stolen diameter, estimated in both directions and over both generations of selection, were found to lie within the range 0.28-0.44; significant shifts in population means for stolen diameter were demonstrated. Selection for thin profuse stolons and for thick s parse stolons was effective, but because of negative correlations betw een stolen diameter and both stolen length and number, selection for t hin sparse stolons or thick profuse stolons was ineffective.