Premium
Nonstructural Carbohydrate Concentration during Field Wilting of PM‐ and AM‐Cut Alfalfa
Author(s) -
Morin Chantale,
Tremblay Gaëtan F.,
Bélanger Gilles,
Bertrand Annick,
Castonguay Yves,
Drapeau Raynald,
Michaud Réal,
Berthiaume Robert,
Allard Guy
Publication year - 2012
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj2011.0365
Subject(s) - wilting , dry matter , zoology , medicago sativa , agronomy , starch , morning , biology , chemistry , botany , food science
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.