Seed from six Australian near-isogenic lines of wild oat were germinated and grown in controlled-environment growth chambers under either ambient CO₂ (357 parts per million by volume [ppmv]) or elevated CO₂ (480 ppmv) at 20/16 C or 23/19 C. Three soil moisture treatments—−0.01 MPa (field capacity), −0.10 MPa, or −1.00 MPa—were imposed. Wild oat lines grown under elevated CO₂ had higher seed production and greater plant dry weights, although the response of these variates involved a complex of interactions with temperature, soil moisture, and line. Plant height varied with wild oat line, and plants grown at 20/16 C were taller than those grown at 23/19 C. At 23/19 C, time taken to mature was reduced for some wild oat lines, and elevated CO₂ reduced the time taken to maturity for some lines at 20/16 C. There was no significant difference in the level of dormancy developed in freshly harvested caryopses between the two CO₂ treatments, but an effect was present in seed that had been after-ripened for 193 d. These results indicate that the main climate change variables ([CO₂], soil moisture, and increased temperature) directly influence the growth and development of wild oat and are likely to affect the population dynamics of this species.

Nomenclature: Wild oat, Avena fatua AVEFA.