Defoliation Effects on Production and Morphological Development of Little Bluestem

Abstract

Response of key warm-season grasses to time, frequency, and duration of defoliation is needed to develop grazing systems for the Nebraska Sandhills. A 3year (1986 to 1988) study was conducted on a Valentine fine sand (mixed, mesic Typic Ustipsamments) at the Gudmundsen Sandhills Laboratory near Whitman, Nebraska, to determine the effect of defoliation on little bluestem [Sch&uchyrium scopurium (Michx.) Nash]. Treatments were: 1 defoliation (to 7 cm)

Effects of Root-trimming and Cutting-heights on Growth Performance of Potted Native Warm-season Grasses

“…In fact, in all species, the 20-cm cutting-height produced >100% more forage DM than its 10-cm counterpart. The treatment differences in forage biomass were actually consistent with reported negative effects of severe defoliation on plant growth (Ferraro & Oesterheld, 2002 warm-season grasses by over 60% (Mullahey, 1990;Forwood & Magai, 1992). This is so because proportions of photosynthetic tissue retained on defoliated plants usually influence how quickly they repair their damaged tissues (Oesterheld & McNaughton, 1991;Lee et al, 2000;Ferraro & Oesterheld, 2002).…”

Little Bluestem Tiller Defoliation Patterns under Continuous and Rotational Grazing

“…Uttle bluestem plants should not receive multiple defoliations in consecutive years unless the purpose is to weaken large plants so that remaining tillers at the periphery will form new, smaller plants (Mullahey et al 1990). …”

“…Dwyer et al (1963), from clipping studies in Oklahoma, indicates increased frequency rather than high intensity is more detrimental to little bluestem. Mullahey et al (1990) recommends little bluestem be defoliated a single time in June or July; a single defoliation in August or multiple defoliations severely reduce annual dry matter yield, tiller number, tiller weight, and bud number. Intense herbivory reduces individual little bluestem plant basal area and increases plant density by fragmenting individual large plants (Butler and Briske 1988).…”

“…Uttle bluestem may not persist if exposed to multiple, close defoliations during the growing season (Mullahey et al 1990). Dwyer et al (1963), from clipping studies in Oklahoma, indicates increased frequency rather than high intensity is more detrimental to little bluestem.…”

“…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). …”