Nonstructural Carbohydrate Concentration during Field Wilting of PM- and AM-Cut Alfalfa
- Chantale Morina,
- Gaëtan F. Tremblay *b,
- Gilles Bélangerb,
- Annick Bertrandb,
- Yves Castonguayb,
- Raynald Drapeauc,
- Réal Michaudb,
- Robert Berthiaumed and
- Guy Allarda
- a Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, 2425 rue de l'Agriculture, Québec, QC, Canada G1V 0A6
b Agriculture and Agri-Food Canada, Soils and Crops Research and Development Centre, 2560 Hochelaga Blvd, Québec, QC, Canada G1V 2J3
c Agriculture and Agri-Food Canada, Research Farm, 1468 St-Cyrille Street, Normandin, QC, Canada G8M 4K3
d Agriculture and Agri-Food Canada, Dairy and Swine Research and Development Centre, 2000 College Street, Sherbrooke, QC, Canada J1M 0C8
Alfalfa (Medicago sativa L.) cut in the late afternoon has a greater nonstructural carbohydrate (NSC) concentration than AM-cut alfalfa but this difference might not be maintained during wilting. We monitored NSC concentration of PM- and AM-cut alfalfa during wilting in narrow and wide swaths. Field-grown alfalfa was cut either at 1800 h (PM) on days without rain (Day 0) or at 0800 h (AM) the following morning (Day 1) in seven growth cycles over 3 yr. Samples taken during wilting were analyzed for NSC (soluble carbohydrates + starch). At cutting, PM-cut alfalfa had consistently greater NSC concentration [+6 to 54 g kg−1 of dry matter (DM)] than AM-cut alfalfa. The NSC concentration decreased during wilting at rates that depended on growth cycles (0.2–3.5 g kg−1 DM h−1 on Day 1) but this decline was similar for AM- and PM-cut alfalfa. When cut alfalfa reached 350 g DM kg−1 fresh matter (FM) on Day 1, NSC concentration was greater for PM- than for AM-cut alfalfa (average of 15 with a range of 4–37 g kg−1 DM) and greater for the wide than narrow swaths (average of 7 with a range of 1–11 g kg−1 DM). Photosynthesis continued for 3 h on the morning of AM cutting for both PM- and AM-cut alfalfa until DM concentration reached approximately 350 g DM kg−1 FM. The combination of late PM-cutting and wilting in wide swaths can be used to increase the NSC concentration of wilted alfalfa.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2012. . Copyright © 2012 by the American Society of Agronomy, Inc.