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Effect of defoliation severity on regrowth and nutritive value of perennial ryegrass dominant swards


Lee, JM and Donaghy, DJ and Roche, JR, Effect of defoliation severity on regrowth and nutritive value of perennial ryegrass dominant swards, Agronomy Journal, 100, (2) pp. 308-314. ISSN 0002-1962 (2008) [Refereed Article]

DOI: doi:10.2134/agronj2007.0099


The height or mass to which swards are defoliated can potentially affect regrowth. A field study was undertaken to determine the response of perennial ryegrass (Lolium perenne L.) dominant swards to defoliation severity over repeated defoliations during a period of low water-soluble carbohydrate (WSC) accumulation (late spring to mid-autumn due to active leaf growth and relatively high respiration). Five defoliation severities (defoliation to a residual stubble height [RSH] of 20, 40, 60, 80, or 100 mm) were replicated five times in a Latin square design. During a 6-mo period, treatment plots were defoliated seven times using a rotary lawnmower. Analysis of data indicated a quadratic relationship between RSH and total herbage production, with total yields of 12,190, 13,440, 13,730, 13,320, and 11,300 kg DM ha-1 for swards defoliated to 20, 40, 60, 80, and 100 mm, respectively. Regression analyses identified 56 mm as the optimal RSH for herbage production, but there was little biological significance between 40 and 80 mm RSH. Total WSC content per tiller was reduced with increasing defoliation severity. The relationship between WSC content per tiller and subsequent herbage yield was quadratic, with peak herbage yield at 9.4 mg tiller-1 (60 mm RSH). The data indicate that between September (spring) and April (autumn), herbage production of temperate perennial ryegrass-dominant swards is maximized when defoliation severity results in post-grazing stubble heights of 40 to 80 mm. Copyright © 2008 by the American Society of Agronomy. All rights reserved.

Item Details

Item Type:Refereed Article
Research Division:Agricultural, Veterinary and Food Sciences
Research Group:Crop and pasture production
Research Field:Agronomy
Objective Division:Animal Production and Animal Primary Products
Objective Group:Pasture, browse and fodder crops
Objective Field:Sown pastures (excl. lucerne)
UTAS Author:Lee, JM (Mr Jenn Ming Lee)
UTAS Author:Donaghy, DJ (Associate Professor Danny Donaghy)
UTAS Author:Roche, JR (Dr John Roche)
ID Code:51661
Year Published:2008
Web of Science® Times Cited:59
Deposited By:Agricultural Science
Deposited On:2008-04-10
Last Modified:2009-05-19

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