ABSTRACT
Summary Grassbreeders like to observe plants separately, and therefore they make use of wide spacing. In this paper a procedure is described in which plants are spaced in a sward of another grass. In this way plants can be assessed separately throughout the test, although they are growing in a dense crop. When plants are tested under wide spacing in the sward of another species, the differences that exist between plants and between progenies show up earlier and are more pronounced than in plants tested under noncompetitive spacing. Plants that are weak performers in the sward will disappear. Ease of assessment depends on suppression by the companion crop and on that crop's height and color. The companion crop has a greater influence on the production level than on the yield ranking of the entries, the latter not being substantially changed as a rule. Experimental varieties obtained by selecting perennial ryegrass plants in swards of timothy and of cocksfoot proved to be highly persistent. They showed good regrowth after cutting, with few plants disappearing. As a consequence the sward remained dense and productive. This kind of resistance to sward deterioration is very important at high production levels.
