Effect of defoliation management, based on leaf stage, on perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under dryland conditions. 1. Regrowth, tillering and water‐soluble carbohydrate concentration

Abstract

Effect of defoliation management, based on leaf stage, on perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under dryland conditions. 1. Regrowth, tillering and water-soluble carbohydrate concentration Abstract A field study was undertaken between April 2003 and May 2004 in southern Tasmania, Australia to quantify and compare changes in herbage productivity and water-soluble carbohydrate (WSC) concentration of perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under a defoliation regime based on leaf regrowth stage. Defoliation interval was based on the time taken for two, three or four leaves per tiller to fully expand. Dry-matter (DM) production and botanical composition were measured at every defoliation event; plant density, DM production per tiller, tiller numbers per plant and WSC concentration were measured bimonthly; and tiller initiation and death rates were monitored every 3 weeks. Species and defoliation interval had a significant effect (P < 0AE05) on seasonal DM production. Prairie grass produced significantly more (P < 0AE001) DM than cocksfoot and ryegrass (5AE7 vs. 4AE1 and 4AE3 t DM ha )1 respectively). Plants defoliated at the two-leaf stage of regrowth produced significantly less DM than plants defoliated at the three-and four-leaf stages, irrespective of species. Defoliation interval had no effect on plant persistence of any species during the first year of establishment, as measured by plant density and tiller number. However, more frequent defoliation was detrimental to the productivity of all species, most likely because of decreased WSC reserves. Results from this study confirmed that to maximize rates of regrowth, the recommended defoliation interval for prairie grass and cocksfoot is the four-leaf stage, and for perennial ryegrass between the two and three-leaf stages.

Defoliation frequency effects on winter forage production and nutritive value of different entries ofDactylis glomerataL.

“…This effect of defoliation frequency on DM production was similar for all the tested entries. These results are in agreement with previous grazing and defoliation studies (Turner et al 2006b;Pontes et al 2007), which reported D. glomerata stand deterioration over time due to frequent defoliation.…”

“…This could explain the reduced DM production under frequent defoliation during the second year. increased DM production under infrequent defoliation during the second year could be attributed to greater WSC assimilation and therefore leaf and tiller DM accumulation during the subsequent recovery period (Rawnsley et al 2002;Turner et al 2006b). …”

“…Thus, the recommended defoliation interval for Dactylis glomerata is the four-leaf stage in order to maximise rates of regrowth (Turner et al 2006b), and two to three leaves per tiller for Lolium perenne (Donaghy & Fulkerson 1997). The developmental rate of leaves is closely related to climatic conditions (Davies & Thomas 1983;Casal et al 1985) and consequently to the season of the year.…”

Forage Options for Dairy Farms with Reduced Water Availability in the Southern Murray Darling Basin of Australia

“…Repeated defoliation before the two-leaf stage depleted water soluble carbohydrate reserves and delayed regrowth of leaves and roots, while defoliation after the three-leaf stage resulted in the loss of older leaves through death and decay [94]. Leaf-stage grazing rules based on similar principles have been developed for cocksfoot (Dactylis glomerata L.) [95,96], prairie grass (Bromus willdenowii Kunth.) [97,98], and tall fescue [31].…”

Simple versus diverse pastures: opportunities and challenges in dairy systems

“…Unfortunately the grazing management requirements to optimise DM yield, persistence and nutritive value of many grasses, legumes and forbs (Sanderson et al 2003, Labreveux et al 2006, Turner et al 2006, Lee et al 2012 do not align with each other or align with perennial ryegrass and white clover. However, there are examples of some species combinations with aligning grazing management which could be components of diverse pastures (e.g.…”