Abstract:
Climate change refers to a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period (typically decades or longer). Under changing climate, high temperature and elevated CO
2 are predicted to increase in frequency, causing serious challenges to sustain global food security. Among the 86-plant species which supply most of the world's food, only five are C
4 species. Among 18 most troublesome weeds in the world, 14 are C
4 species. Most of troublesome weeds species are C
4, while most major crops areC
3photosynthetic pathway. Various studies revealed that both crops and weeds respond to changing climate scenario. Weeds comes under C
3 pathway may dominate under elevated CO
2 conditions, whereas in elevated temperature, C
4 weeds may dominate. The interactive effect of elevated CO
2 and temperature showed that C
4 weeds dominate over C
3 weeds. Crop-weed competition was low at elevated CO
2 whereas high under elevated temperature. The interactive effect of elevated CO
2 and temperature on crop-weed competition was high. Hence, weed management is considered as a major threat to future agriculture.