Water-Soluble Carbohydrate Recovery in Pastures of Perennial Ryegrass (<i>Lolium perenne</i> L.) and Pasture Brome (<i>Bromus valdivianus</i> Phil.) Under Two Defoliation Frequencies Determined by Thermal Time

• Main Authors: Iván Calvache, Oscar Balocchi, Máximo Alonso, Juan Pablo Keim, Ignacio López
• Format: Article
• Language: English
• Published: MDPI AG 2020-11-01
• Series: Agriculture
• Subjects: accumulate growing degree days; phyllochron; grass regrowth; leaf sheaths; blades
• Online Access: https://www.mdpi.com/2077-0472/10/11/563
• ISSN: 2077-0472

The objectives of the experiment were to (i) examine the dynamics of WSC use and the recovery of leaf sheaths and blades of <i>Bromus valdivianus</i> Phil. and <i>Lolium perenne</i> L. subjected to two defoliation frequencies (DFs) determined by thermal time (TT); (ii) evaluate how DF influenced regrowth and accumulated herbage mass (AHM) during fall. Defoliation was carried out at frequencies of 135 and 270 accumulated growing degree days (AGDDs) for both species. Twelve plots were arranged in a three-block design. All plots had a conditioning period to establish the assigned DF prior to sampling. From the start of the experiment, “cores” were collected from each plot every three days until the DF was reached. Every core was separated into leaf and sheath material before measuring the WSC concentration. <i>Lolium perenne</i> had concentrated more WSCs than <i>B. valdivianus</i>. Both species adapted their WSC recovery according to the DF. The recovery of WSC was faster under a DF of 135 AGDDs than that of 270 AGDDs. Leaf sheaths contained more WSCs than leaf blades and were identified as WSC storage organs. This period can be used as the optimal defoliation interval in <i>B. valdivianus</i> and <i>L. perenne</i> grazing systems.