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A canopy photosynthesis model to predict the dry matter production of cocksfoot pastures under varying temperature, water and nitrogen regimes

Citation

Peri, PL and Moot, DJ and McNeil, DL, A canopy photosynthesis model to predict the dry matter production of cocksfoot pastures under varying temperature, water and nitrogen regimes, Grass and Forage Science, 58, (4) pp. 416-430. ISSN 0142-5242 (2003) [Refereed Article]

DOI: doi:10.1111/j.1365-2494.2003.00395.x

Abstract

Daily net canopy photosynthesis (Pn) of cocksfoot (Dactylis glomerata L.) was predicted for combinations of temperature, herbage nitrogen (N) concentration and water status from the integration of models of leaf photosynthesis of the light-saturated photosynthetic rate (Pmax), photosynthetic efficiency (α) and the degree of curvature (θ) of leaf light-response curves. The effect on Pn, maximum Pn (Pn max) and the optimum leaf area index (LAI at Pn max) was examined when any one of these factors was limiting. The ranges that gave the optimum values of Pn (Pn max = 30.8-33.5 g CO 2 m-2 d-1) for temperature (19-22°C) and N concentration (40-50 g N kg-1 DM) were smaller than those for net leaf photosynthesis. Also, Pn fell to 0 at a lower level of water stress (pre-dawn leaf water potential, ψIp = -12.5 bar) than for Pmax. The canopy photosynthesis model was then used to compare predicted and measured dry matter (DM) production for cocksfoot pastures grown under a diverse range of environmental conditions with field data from New Zealand and Argentina. To predict DM production leaf area index and leaf canopy angle were included from field measurements. The model explained about 0.85 of the variation in cocksfoot DM production for the range of 6.5-134 kg DM ha -1 d-1. The canopy model overestimated the DM production by 0.10 which indicates that a further Pmax function for leaves of different ages and a partitioning sub-model may be needed to improve predictions of DM production.

Item Details

Item Type:Refereed Article
Research Division:Agricultural and Veterinary Sciences
Research Group:Crop and Pasture Production
Research Field:Crop and Pasture Biochemistry and Physiology
Objective Division:Animal Production and Animal Primary Products
Objective Group:Pasture, Browse and Fodder Crops
Objective Field:Sown Pastures (excl. Lucerne)
Author:McNeil, DL (Professor David McNeil)
ID Code:41780
Year Published:2003
Web of Science® Times Cited:12
Deposited By:Agricultural Science
Deposited On:2007-01-30
Last Modified:2007-01-30
Downloads:0

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