Breeding for improved frost-seeded red clover seedling establishment

Abstract

In the colder parts of the United States, in late winter after disappearance of snow cover, red clover (Trifolium pratense) is often broadcast seeded into forage legume-depleted grass pastures to increase pasture forage quality. This method of establishment is referred to as frost seeding. However, in an estimated 30-40% of frostseeded pastures in Wisconsin, USA the legumes fail to establish. In this study 40 red clover halfsib families from one breeding population and six check populations were evaluated for spring 2005 establishment by 1) broadcast seeding into existing pasture under frost-seeded conditions and 2) standard drill seeding into 15 cm-spaced rows. In June 2005 seedling counts and heights were measured on halfsib family plots. Narrow sense heritability estimates on a halfsib family basis for seedling stand counts under frost- and drill-seeded establishment were h2 = 0.02 and 0.21 respectively. Heritabilities for seedling height under frost- and drill-seeded establishment were h2 = 0.50 and 0.26. Genetic correlations between seedling counts and heights under frost- and drill-seeded establishment were rA = 0.42 and 0.19 respectively. No significant genetic correlations between frost- and drill-seeded heights (rA = -0.09) or seedling counts (rA = 0.20) were detected. These results suggest that seedling performance in frost-seeded conditions is a distinct trait from seedling performance in standard drill-seeded conditions and that each needs a separate selection program.