HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Figures Only Full Text Free Full Text (PDF) Free Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (15) Citing Articles via Google Scholar Google Scholar Articles by Skinner, R.H. Articles by Hanson, J. D. Search for Related Content PubMed Articles by Skinner, R.H. Articles by Hanson, J. D. Agricola Articles by Skinner, R.H. Articles by Hanson, J. D.

CROP PHYSIOLOGY & METABOLISM

Carbon and Nitrogen Reserve Remobilization Following Defoliation

Nitrogen and Elevated CO₂ Effects

^a USDA, ARS, Pasture Systems & Watershed Management Research Laboratory, Building 3702 Curtin Road, University Park, PA 16802 USA
^b USDA, ARS, Rangeland Resources Research Unit, Crops Research Laboratory, 1701 Center Avenue, Ft. Collins, CO 80526 USA
^c USDA, ARS, Northern Great Plains Research Laboratory, P.O. Box 459, Mandan, ND 58554 USA

rhs7{at}psu.edu

Early regrowth following defoliation of forage species often depends on remobilization of nitrogen and non-structural carbohydrate (TNC) reserves stored in roots and crowns. The degree to which TNC and N remobilization contribute to regrowth can depend on internal concentrations and on external CO₂ and N supplies. We studied the effect of CO₂ and N supply on reserve remobilization during the first 20 d following defoliation of 9-wk-old alfalfa (Medicago sativa L.), western wheatgrass [Pascopyrum smithii (Rydb) A. Love], and blue grama [Bouteloua gracilis (H.B.K.) Lag ex Steud]. plants. Reserve remobilization was studied in controlled-environment chambers set at either ambient (350 µmol mol^-1) or elevated (700 µmol mol^-1) CO₂. Plants were fertilized twice weekly with Hoaglands solution containing either 0 mg L^-1 (low N) or 400 mg L^-1 N (high N). Elevated CO₂ increased the total amount and percent of available TNC that was remobilized in alfalfa, and the amount of remobilized TNC in western wheatgrass, but reduced TNC remobilization in blue grama. Nitrogen fertilization had little effect on TNC remobilization at ambient CO₂, but increased remobilization in alfalfa and reduced remobilization in the two grasses under elevated CO₂. Alfalfa remobilized a greater percentage of its root and crown N reserves than either grass species. Nitrogen remobilization was highest under high N and ambient CO₂ conditions for all species. Nitrogen deficiency and elevated CO₂ reduced N remobilization and the contribution of remobilized N to shoot regrowth.

Abbreviations: TNC, total nonstructural carbohydrates • SDW, Structural dry weight

This article has been cited by other articles:

				D. Zhao, C. T. MacKown, P. J. Starks, and B. K. Kindiger Interspecies Variation of Forage Nutritive Value and Nonstructural Carbohydrates in Perennial Cool-Season Grasses Agron. J., May 7, 2008; 100(3): 837 - 844. [Abstract] [Full Text] [PDF]

				A. Bertrand, D. Prevost, F. J. Bigras, and Y. Castonguay Elevated Atmospheric CO2 and Strain of Rhizobium Alter Freezing Tolerance and Cold-induced Molecular Changes in Alfalfa (Medicago sativa) Ann. Bot., February 1, 2007; 99(2): 275 - 284. [Abstract] [Full Text] [PDF]

				Y. C. Newman, L. E. Sollenberger, K. J. Boote, L. H. Allen Jr., J. M. Thomas, and R. C. Littell Nitrogen Fertilization Affects Bahiagrass Responses to Elevated Atmospheric Carbon Dioxide Agron. J., March 2, 2006; 98(2): 382 - 387. [Abstract] [Full Text] [PDF]

				C. Dhont, Y. Castonguay, P. Nadeau, G. Belanger, and F.-P. Chalifour Alfalfa Root Nitrogen Reserves and Regrowth Potential in Response to Fall Harvests Crop Sci., January 1, 2003; 43(1): 181 - 194. [Abstract] [Full Text] [PDF]

				P. M. Santos, B. Thornton, and M. Corsi Nitrogen dynamics in the intact grasses Poa trivialis and Panicum maximum receiving contrasting supplies of nitrogen J. Exp. Bot., November 1, 2002; 53(378): 2167 - 2176. [Abstract] [Full Text] [PDF]

				C. Dhont, Y. Castonguay, P. Nadeau, G. Belanger, and F.-P. Chalifour Alfalfa Root Carbohydrates and Regrowth Potential in Response to Fall Harvests Crop Sci., May 1, 2002; 42(3): 754 - 765. [Abstract] [Full Text] [PDF]

				J. A. Morgan, R.H. Skinner, and J. D. Hanson Nitrogen and CO2 Affect Regrowth and Biomass Partitioning Differently in Forages of Three Functional Groups Crop Sci., January 1, 2001; 41(1): 78 - 86. [Abstract] [Full Text] [PDF]