Quantifying the effect of drought on carbon dioxide-induced changes in competition between a C3 crop (tomato) and a C4 weed (Amaranthus retroflexus)
Article first published online: 13 JUL 2011
© Published 2011. This article is a US Government work and is in the public domain in the USA. Weed Research © 2011 European Weed Research Society
Volume 51, Issue 6, pages 591–600, December 2011
How to Cite
VALERIO, M., TOMECEK, M. B., LOVELLI, S. and ZISKA, L. H. (2011), Quantifying the effect of drought on carbon dioxide-induced changes in competition between a C3 crop (tomato) and a C4 weed (Amaranthus retroflexus). Weed Research, 51: 591–600. doi: 10.1111/j.1365-3180.2011.00874.x
- Issue published online: 2 NOV 2011
- Article first published online: 13 JUL 2011
- Received 7 January 2011 Revised version accepted 19 May 2011 Subject Editor: Clarence Swanton, Guelph, Canada
- redroot pigweed;
Valerio M, Tomecek MB, Lovelli S & Ziska LH (2011). Quantifying the effect of drought on carbon dioxide-induced changes in competition between a C3 crop (tomato) and a C4 weed (Amaranthus retroflexus). Weed Research51, 591–600.
Recent and projected increases in atmospheric carbon dioxide concentration ([CO2]) and subsequent effects on climate are likely to alter competitive outcomes of weeds and crops. Rising [CO2] per se could increase the competitive ability of C3 crops relative to C4 weeds. However, such an outcome may depend on other climatic variables. In this study, tomato, a C3 crop species, was grown from emergence to anthesis using replacement series mixtures with Amaranthus retroflexus, a C4 weed species at three different [CO2], 400, 600 and 800 μmol mol−1, with and without water stress. Under well-watered conditions, leaf photosynthetic rates and plant height, leaf area and biomass all increased with elevated [CO2] for tomato relative to A. retroflexus, consistent with the kinetics of C3 photosynthesis. However, if water was limiting, a significant positive effect of [CO2] was noted for plant height and biomass of A. retroflexus with increased competition. This result may be related to a greater increase in leaf water potential with rising [CO2] for A. retroflexus relative to tomato under water stress. Overall, these are the first data to suggest that increases in atmospheric CO2 could still exacerbate crop losses from a C4 weed, even with a C3 crop, if drought occurs.