Effects of autumn and spring defoliation management on the dry-matter yield and herbage quality of perennial ryegrass swards throughout the year

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• 作者：D. C. Lawrence ; M. O'Donovan ; T. M. Boland and E. Kennedy
• 刊名：Grass and Forage Science
• 出版年：2017
• 出版时间：March 2017
• 年：2017
• 卷：72
• 期：1
• 页码：38-49
• 全文大小：677K
• ISSN：1365-2494

文摘

A small-plot experiment was conducted in south-west Ireland to investigate (i) the effects of pre-closing regrowth interval and closing date on dry-matter (DM) yield and sward structural and composition characteristics, during the autumn–winter and spring opening periods, and (ii) subsequent carryover effects. The study used a randomized block design with a factorial arrangement of treatments (4 closing dates × 2 opening dates) with a split plot (two pre-closing regrowth intervals). The long pre-closing (LPC) interval began on 9 August, and the short pre-closing interval (SPC) started on 15 September. The autumn closing dates were as follows: 1 October (CD1), 15 October (CD2), 1 November (CD3) and 14 November (CD4). Plots were defoliated again on 1 February (EOD) or 1 March (LOD). On the LPC treatment, herbage yield increased from CD1 (2463 kg DM ha⁻¹) to CD3 (3185 kg DM ha⁻¹). On the SPC treatment, herbage yield was similar for CD3 and CD4, indicating a ceiling in herbage accumulation. For each 1-d delay in closing date between CD1 and CD4, the opening herbage yield was reduced by 10 kg DM ha⁻¹. Herbage quality decreased as the closing date was delayed; DMD and CP decreased by 0·06 and 12 g kg DM⁻¹, respectively, between CD1 and CD4. The EOD resulted in increased leaf and decreased dead proportions over the LOD treatments. A balance between autumn CD and spring OD needs to be achieved to ensure a sufficient supply of high-quality grass in spring.