Influence of recurrent selection for flowering on flowering and yields in kura clover

Abstract

These investigations were conducted to determine the effectiveness of first- and second-season selection programs for increasing forage and seed yield in kura clover (Trifolium ambiguum Bieb.). ‘Rhizo’ kura clover, the base population, was grown as spaced plants in two programs for six generations of selection for flowering in the seedling and second seasons. Remnant seed for each generation of selection was used to establish spaced plant and broadcast evaluation trials. The first-season selection program was effective in increasing flowering not only in the first season, but for two subsequent seasons. The second-season selection for flowering had little or no effect. However, vigor, forage and seed yields were not increased by either program, and the first-season program progressively reduced vigor and forage yields as generations of selection increased. The cause of this is unknown but may be associated with inbreeding depression or detrimental physiological effects of first-season flowering. Reselection to eliminate possible inbreeding effects is being conducted to further examine the possibility of increasing seedling and aftermath vigor in kura clover.