Water use and growth responses of dryland wheat grown under elevated [CO2] are associated with root length in deeper, but not upper soil layer

Research output: Contribution to journalArticlepeer-review


  • Shihab Uddin
  • Markus Löw
  • Shahnaj Parvin
  • Glenn Fitzgerald
  • Helale Bahrami
  • Roger Armstrong
  • Garry O'Leary

External organisations

  • University of Melbourne
  • Bangladesh Agricultural University
  • Department of Economic Development
  • Department of Economic Development, Jobs, Transport and Resources, Horsham, Victoria, Australia.
  • Faculty of Veterinary and Agricultural Sciences
  • AgriBio
  • School of Ecosystem and Forest Sciences


This study investigated crop water use of wheat grown in a dryland Mediterranean-type environment under elevated atmospheric CO2 concentrations ([CO2]). Two related cultivars, contrasting in agronomic features (cvs. Scout and Yitpi; Scout has good early vigour and high transpiration efficiency), were grown under ambient [CO2] (a[CO2], ∼400 μmol mol−1) and elevated [CO2] (e[CO2], ∼550 μmol mol−1) in the Australian Grains Free Air CO2 Enrichment (AGFACE) facility for two growing seasons. Each year, an irrigation treatment (rainfed versus irrigated) was imposed within the CO2-treatments. Normalised difference vegetation index (as surrogate for canopy cover) and root length in the upper (0 cm–32 cm) and deeper (33 cm–64 cm) soil layers were measured at stem-elongation and anthesis. Elevated [CO2] stimulated root length of wheat in both upper and deeper soil layers, and this stimulation was modified by cultivars and irrigation regimes. Across cultivars and all treatments, water use, biomass and grain yield were positively associated with root length in the deeper soil layer but not with root length in the upper soil layer. The ‘CO2 fertilisation effect’ on biomass and grain yield was of similar magnitude under both irrigated and rainfed conditions. Although e[CO2] did not increase canopy cover in these experiments, the CO2 effect on water use depended on cultivars and irrigation regimes. Despite greater e[CO2]-induced stimulation of tillers and spikes, the cv. Scout did not receive more biomass or grain yield benefit from the ‘CO2 fertilisation effect’ compared to cv. Yitpi.


Original languageEnglish
Pages (from-to)170-181
Number of pages12
JournalField Crops Research
Early online date26 May 2018
Publication statusPublished - 1 Jul 2018


  • Climate change, Dryland agriculture, FACE, NDVI, Root length, Water use, Yield

ASJC Scopus subject areas

Sustainable Development Goals