ABSTRACT
The dynamics of competition between weed and crop plants are affected by environmental conditions and have been shown to change with CO
enrichment
(Patterson and Flint 1980). Differential responses of C
plants (carbon from CO
initially fixed into 3-carbon compounds; e.g.,
Hordeum vulgare
,
Avena fatua
,
Amaranthus retroflexus
) and C
plants (carbon from CO
initially fixed into 4-carbon compound; e.g.,
Setaria viridis
) to elevated CO
and temperature may cause shifts in their competitive interactions. These changes have particular significance given that most of the world’s crop species are C
plants, many of the major weed species are C
plants, and that C
plants are expected to benefit more from elevated CO
than C
plants. While this might suggest that crops will gain a competitive advantage over most weeds, other factors, such as changes in herbicide efficacy, may come into play and limit this advantage and decrease potential yield increases in crops. While many studies have examined the effects of environmental change on crop and weed interactions, relatively few have included the effects of environmental change on herbicide efficacy.
