The experiment was carried out to characterize the morphogenic response of Lolium multiflorum cv. "Comum" in intensive utilization systems using nitrogen (N) fertilizer range from 90 to 180kg.ha-1 of N, in mixture or not with Arrowleaf Clover. The experiment was conducted in an area of the Department of Animal Science of the Universidade Federal de Santa Maria, Brazil, from July 20th to September 23th, 2002. Beef heifers were used in continuous grazing with variable stocking rate using put and take technique for the adjustment of the stocking rate to a herbage allowance of 10% of the live weight. To evaluate the dynamics growth of the species, the marked tillers techniquewas used. The experimental design was complete randomized with 63 repetitions. The following treatments were used: italian ryegrass + oat + 180kg.ha-1 of N (N180); italian ryegrass + oat + 90kg.ha-1 of N + supplementation (N90+S); italian ryegrass + oat + 120kg.ha-1 of N + arrowleaf clover (N120+AC). The animals of the treatment N90+S were supplemented with ground sorghum grain at 1% of the live weight. The leaves appearance rate (LAR), leaves elongation rate (LER) and leaves lifespan (LL) were evaluated. Treatments receiving the highest N level (N180 and N120+AC) had in the first period higher LER. The treatment N90+S showed similar result (4,95 mm.tiller-1.day-1) only in the second period. In an average of two periods, there was not a significant difference between treatments. The treatment N120+AC had larger LL and lower LAR in the first period than the others, and it didn't differ of these in the last period. In conclusion, intensive systems of utilization of sward with levels from 90 to 180kg.ha-1 of N, in mixture or not with Arrowleaf Clover in grazing conditions, didn't affect the morphogenic characteristic of ryegrass.
marked tillers; Avena strigosa; nitrogen; continuous grazing; Trifolium vesiculosum
