Gains in annual DMY from forage gra

Gains in annual DMY from forage grass breeding during the last 50 years have varied more between locations than species (Table 1). The highest gains of 4–6% per decade have been made in north-western Europe for perennial ryegrass, in southern France for Italian ryegrass and in Italy for tall fescue and cocksfoot. In the USA very little progress has been made in improving the annual DMY of either cocksfoot or smooth bromegrass.
Differences among ryegrass varieties in annual DMY are usually greater in the second and third harvest years than in the first harvest year, indicating that improved persistency has contributed to the gains. Very few routine variety trials, or experiments specifically designed to test gains from breeding, have been extended beyond 3 full harvest years. The effect of improved persistency on DMY is highly dependent on