Interactive effect of elevated CO2, drought and weed competition on carbon isotope discrimination (Δ13C) in wheat (Triticum aestivum) leaves

An experiment was conducted in open top chambers (OTCs) during 2006-07 to study the carbon isotope discrimination (Delta C-13) in wheat (Triticum aestivum L. emend Fiori & Paol.) leaves in response to elevated CO2, drought and competition by weeds (Phalaris minor, Chenopodium album and Avena fatua). It was observed that drought and weed competition had decreased the Delta whereas, elevated CO2 had increased the Delta and partially ameliorated the negative effects of drought and weeds on Delta. However, the Delta in wheat was not much influenced by stress but, by elevated CO2 when it was in association with P. minor suggesting the variability in Delta due to variation in competition by different weeds.