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Grazing winter wheat relieves plant water stress and transiently enhances photosynthesis

Citation

Harrison, MT and Kelman, WM and Moore, AD and Evans, JR, Grazing winter wheat relieves plant water stress and transiently enhances photosynthesis, Functional Plant Biology, 37, (8) pp. 726-736. ISSN 1445-4408 (2010) [Refereed Article]

Copyright Statement

Copyright 2010 CSIRO

DOI: doi:10.1071/FP10040

Abstract

To model the impact of grazing on the growth of wheat (Triticum aestivum L.), we measured photosynthesis in the field. Grazing may affect photosynthesis as a consequence of changes to leaf water status, nitrogen content per unit leaf area (Na) or photosynthetic enzyme activity. While light-saturated CO2 assimilation rates (Asat) of field-grown wheat were unchanged during grazing, Asat transiently increased by 33-68% compared with ungrazed leaves over a 2-to 4-week period after grazing ended. Grazing reduced leaf mass per unit area, increased stomatal conductance and increased intercellular CO2 concentrations (Ci) by 36-38%, 88-169% and 17-20%, respectively. Grazing did not alter Na. Using a photosynthesis model, we demonstrated that the increase in Asat after grazing required an increase in Rubisco activity of up to 53%, whereas the increase in Ci could only increase Asat by up to 13%. Increased Rubisco activity was associated with a partial alleviation of leaf water stress. We observed a 68% increase in leaf water potential of grazed plants that could be attributed to reduced leaf area index and canopy evaporative demand, as well as to increased rainfall infiltration into soil. The grazing of rain-fed grain cereals may be tailored to relieve plant water stress and enhance leaf photosynthesis. © 2010 CSIRO.

Item Details

Item Type:Refereed Article
Keywords:defoliation; herbivory; leaf mass per unit area; Rubisco; specific leaf area; transpiration; Assimilation rate; Evaporative demands; Herbivory; Leaf area; Leaf Area Index; Leaf mass per unit areas; Leaf photosynthesis; Leaf water; Leaf water status
Research Division:Agricultural and Veterinary Sciences
Research Group:Crop and Pasture Production
Research Field:Crop and Pasture Biochemistry and Physiology
Objective Division:Plant Production and Plant Primary Products
Objective Group:Winter Grains and Oilseeds
Objective Field:Wheat
Author:Harrison, MT (Dr Matthew Harrison)
ID Code:84639
Year Published:2010
Web of Science® Times Cited:28
Deposited By:Tasmanian Institute of Agriculture
Deposited On:2013-05-23
Last Modified:2013-06-06
Downloads:0

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