PRODUCTIVITY, QUALITY AND PERSISTENCE OF PERENNIAL RYEGRASS AS INFLUENCED BY CUTTING/FERTILITY MANAGEMENT AND PLOIDY

Abstract

The agricultural value of four diploid and four tetraploid cultivars of perennial ryegrass (Lolium perenne L.) was investigated in the south coastal region of British Columbia under two intensities of cutting/fertility management, over three consecutive production years. The management systems were four cuts a year with fertilizer applied at an annual rate of 300:87:165 kg/ha of N:P:K (4C-300N) and eight cuts a year with 450:131:248 kg/ha of N:P:K (8C-450N). The 8C-450N management resulted in forage of greater nutritive value than the 4C-300N management, in terms of in vitro dry matter (DM) digestibility (716 vs. 681 g/kg) and nitrogen content (31.0 vs. 21.4 g/kg), but the DM content of the herbage was lower (168 vs. 181 g/kg). A greater annual yield of nitrogen was obtained from the 8C-450N management (278 vs. 201 kg/ha) but the annual yields of digestible DM were unaffected by the intensity of management and averaged 6410 kg/ha. Year-to-year fluctuations in the productivity and quality of the harvested forage were relatively small. Diploid cultivars tended to be more productive in digestible DM and nitrogen and higher in DM content than the tetraploid cultivars. However, the diploid cultivars were somewhat lower in in vitro DM digestibility and nitrogen content. It was concluded that the diploid cultivar Talbot and the tetraploid cultivar Barvestra were the most versatile and productive of the eight cultivars. They should be suited to both intensive rotational harvesting, by livestock or machine, and conservation for hay or silage. For strictly intensive rotational grazing or green-chopping purposes, the diploid cultivar Cropper should be equally as good.Key words: Grass, yield, quality, cutting management, nitrogen fertility, nutritive value