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Journal of Environmental Biology

pISSN: 0254-8704 ; eISSN: 2394-0379 ; CODEN: JEBIDP

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    Abstract - Issue May 2008, 29 (3)                                     Back

Diurnal photosynthesis, water use efficiency and light use efficiency of wheat under Mediterranean field conditions

Fatih Evrendilek*1, Jiftah Ben Asher2 and Mehmet Aydin3

1Department of Environmental Engineering, Faculty of Engineering and Agriculture, Abant Izzet Baysal University,

Golkoy Campus, 14280 Bolu, Turkey

2Department of Dryland Agriculture, Institute for Desert Research, Ben-Gurion University of the Negev,

Sede Boqer Campus, 684993, Israel

3Department of Soil Science, Mustafa Kemal University, Antakya-Hatay, 31034, Turkey

(Received: July 27, 2006; Revised received: November 02, 2006; Accepted: December 15, 2006)

Abstract: Photosynthesis and transpiration rates of wheat leaves (Triticum aestivum L.) were measured at 30 min intervals under Mediterranean field conditions, using Photosynthesis Monitor system (PM-48M). The dynamics of net photosynthetic rate (PN), transpiration rate (ET), water use efficiency (WUE), light use efficiency (LUE), stomatal conductance (gs), photosynthetically active radiation (PAR), air temperature (T), relative humidity (RH), and atmospheric CO2 concentration (Catm) were quantified at five rainfed wheat sites with the same stages of development (midflowering) along south-to-north and east-to-west transects for eight days in April. Diurnal PN (3.6 to 6.6 Ķmol m-2 s-1), PAR (392 to 564 Ķmol m-2 sec-1), LUE (0.006 to 0.015) and WUE (0.0001 to 0.011) did not vary significantly across all five wheat sites (p>0.05). PN and ET were strongly coupled and highly correlated with PAR (p<0.001). Best multiple linear regression (MLR) models accounted for 92% of variations in PN as a function of PAR and ET, and 90% in ET as a function of PAR and RH (p<0.001). PN exhibited a peak at mid-morning, and a photosynthetic midday depression under the limiting effects of high evaporative demand. Diurnal variations in WUE and LUE showed a bimodal behavior with the maximum values in early morning and late afternoon.As the impacts of global climate change become increasingly felt, continuous measurements of climate-crop-soil-management interactions under natural conditions play a pivotal role not only in exploring changes in ecophysiological properties of strategic crops for food security such as wheat but also in devising preventive and mitigative management practices to ensure sustained agricultural productivity.

Key words: Photosynthesis, Light use efficiency, Transpiration, Water use efficiency, Wheat

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