Abstract
4 clones of distinctive characters which had been selected and propagated from a variety "Frode", were transplanted in the fall of 1964, to establish 6 kinds of sward which was different in plant density (HD : 400 plants/m^2, LD : 25 plants/m^2) and differentially fertilized with nitrogen (HN : 40g N/m^2, MN : 20g N/m^2, LN : 10g N/m^2). The initial harvests were cut at boot stage (May 17), heading stage (May 24), full bloom stage (June 6) and June 20, and, the second harvests were after each 6 weeks of the each intial cut. Characteristics of each clone judged from the growth of LD sward were : Clone 1-Tallesst plant height with a few tillers, Clone 2-Lower plant height with abundant tillers, Clone 3-Similar plant height and tillering to Clone 2, with leaves of lowest nitrogen concentration, Clone 4-Lowest plant height with weak tillering. 1. The initial yield was higher in the later cutting and the second yield was reverse, resulting in the higher total yield at the later initial harvest (Fig. 7) 2. When the initial harvest was, cut at earlier growth stages, Clone 2 or 3 with strong tillering capacity grew better and contributed much to the yield and density of the sward, whereas Clone 1 with tallest plant height progressively dominated the sward yield as the initial cutting was delayed (Fig. 8) 3. Tall erect clones may gradually dominate the sward when cut at hay or silage stage, instead, short clones with many tillers may maintain their persistency more easily when cut or grazed at earlier growth stages.
