The Frequency and Severity of Defoliation of Individual Tillers in Set‐stocked Swards

Abstract

Individual tillers of S23 ryegrass, in three paddocks set-stocked with sheep at widely differing grazing pressures, were marked and studied from 11 July to 19 August, 1966, and observations were made on the frequency and severity of grazing. The uprooting of tillers, and the destruction of others, were major sources of loss of records. It was found that an acceptable measure of the frequency of defoliation could be made by recording three times a week. In a subsidiary experiment it was shown that repeated handling did not affect the DM yield, the number of tillers or the length of green leaf (G.L.L.) of single plants. Despite the extreme differences in grazing pressure, there were no significant differences between paddocks in the daily increase in the G.L.L. of tillers which were not grazed during a short period of intensive recording. In all three paddocks the sheep tended to graze the tillers with the greatest G.L.L. at any one time, £ind there was evidence of patchy grazing only at the lowest grazing pressure. An increase in grazing pressure resulted in increases in both the frequency and severity of defoliation. Comparisons were made between the product of the frequency X severity of defoliation of individual tillers, and the stocking rate, grazing pressure and herbage consumption on the three paddocks.

Defoliation, Shoot Plasticity, Sward Structure and Herbage Utilization in Pasture: Review of the Underlying Ecophysiological Processes

“…In several instances, defoliation also needs to be characterized by additional parameters, such as its spatial heterogeneity or its timing in relation to plant development, particularly floral initiation. On a tiller basis, the defoliation interval usually varies from low values, typically 7-15 days under intensive continuous grazing management and depending on the stocking density [6,12,26,27], to intermediate values of approximately 20-30 days in rotational grazing, and to high values of approximately 30-60 days in cutting systems. The tiller defoliation interval may reach higher values in extensive systems or where a long rotation is used to stockpile feed.…”

Little Bluestem Tiller Defoliation Patterns under Continuous and Rotational Grazing

“…Hodgson (1966), Hodgson and Ollerenshaw (1969), Allison and Kothmann (1979), Briske and Stuth (1982), and Curll and Wilkins (1982) all confirm that high stocking rates increase efficiency of defoliation. Brown and Stuth (1984) suggest it is possible to modify patterns and degree of utilization by altering stocking rate.…”

“…Clipping little bluestem after apical meristems have been elevated stimulates tillering the first year (Jameson and Huss 1959 (Mullahey et al 1990). This change in the size of plants and plant parts commonly occurs in response to heavy grazing (Hanson et al 1931, Holscher 1945, Weaver and Darland 1947 (Hodgson 1966, Morris 1969, Briske and Stuth 1982, Curll and Wilkins 1982, Hart and Balla 1982, Jensen et al 1990; 2) the relative relationship between defoliation frequency and intensity (Cassady 1953, Owensby et al 1974, Buwai and Trlica 1977, Gammon and Roberts 1978c, Clark et al 1984, Mullahey et al 1990); and 3) the importance of tiller architecture i.e., height, total lamina length and location in the canopy, in determining defoliation probabilities (Greenwood and Arnold 1968, Hodgson and Ollerenshaw 1969, Bartham and Grant 1984, Pierson and Scarnecchia 1987, Heitschmidt et al 1990). …”

Parâmetros nutricionais de forrageiras nativas e exóticas no Vale do Itajaí, Santa Catarina

“…Lista dos acessos de plantas forrageiras exóticas e nativas utilizadas no presente trabalho. (Hodgson & Ollerenshaw, 1969;Chapman & Lemaire, 1993;Mazzanti et al, 1994;Lemaire, 1997). A utilização da adubação foi uma prática favorável aos parâmetros qualitativos das forragens.…”