Interactive effect of elevated CO2 and supplemental N on above- and belowground growth and water use of dryland wheat

Shihab Uddin1 2 3 *, Shahnaj Parvin3 4, Markus Löw2, Sabine Tausz-Posch5, Roger Armstrong6 7, Garry O’Leary6, Glenn Fitzgerald2 6, Michael Tausz5

1NSW Department of Primary Industries, Wagga Wagga Agricultural Institute, Wagga Wagga, NSW 2650, Australia.

2Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Creswick, VIC, Australia.

3Department of Agronomy, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh.
4School of Ecosystem and Forest Sciences, The University of Melbourne, Creswick, VIC, Australia.

5Department of Agriculture, Science and Environment, School of Health and Applied Sciences, CQUniversity Australia, Rockhampton, QLD, Australia.

6Agriculture Victoria, 110 Natimuk Road, Horsham, VIC 3400, Australia.

7Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora, VIC, Australia

*Corresponding author: email:


Elevated atmospheric CO2 concentration (e[CO2]) stimulates biomass and yield of crops through the ‘CO2 fertilisation effect’. Stimulation of biomass with supplemental nitrogen (N) under e[CO2] may influence water use dynamics, which is particularly important in relatively low yielding dryland Mediterranean regions where timing of water limitations interacts with N availability and intra-seasonal variability is high. This study investigated the interactive effect of N supply (with and without supplemental N) and [CO2] (ambient [CO2] and e[CO2]∼550 µmol mol-1) on aboveground biomass, root length and water use of two wheat cultivars putatively differing in N use efficiency using a Free Air CO2 Enrichment (FACE) facility in Horsham, Victoria. Elevated [CO2] stimulated biomass and grain yield, and this stimulation was influenced by both cultivar and N supplementation. The observed differential response of cultivars to e[CO2] and N rates suggests that there is potential to select germplasm that maximises the benefit from CO2 fertilisation under a wide range of soil N availability.



The Australian Society of Agronomy is the professional body for agronomists in Australia. It has approximately 500 active members drawn from government, universities, research organisations and the private sector.

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