Indian Journal of Agronomy

Changes in temperature, and the amount, intensity, frequency, and distribution of rainfall, collectively known as climate change, can have beneficial or adverse effects on weeds interfering with agriculture. Implicit in discussion of weed management and climate change is the assumption that we know what to do in relation to soil and crop management, but these strategies might not apply to the unexpected future climate change conditions, particularly weed menace. There is confusion in interpreting weed management for the weather fluctuation in a region, as there is a clear-cut distinction between climate change and climate variability. Soil warming could enhance the availability of certain elements in the soil by faster ion-diffusion rate and the soil-moisture stress could boom weed proliferation. Judicious agronomic practices would partially help to offset weed pressure, but climate may have over-riding influence on weeds, as they share the same trophic level with crops. Implications of climate change would be identical with crops, aggravating the crop-weed competition. Many of the most troublesome weeds in crop ecosystems follow C₄ pathway. As atmospheric CO₂ increases, it is conceivable that competitive ability of weeds could be similar to C₃ crops, such as rice, if there is no dearth of soil moisture and nutrients. From a weedmanagement perspective, C₄ weeds would flourish under the increased temperature scenario and pose serious yield limitation. It is speculated that reduced water availability due to recurrent/unforeseen droughts would alter the competitive balance between crops and some weed species, intensifying the crop-weed competition pressure. Research conducted indicated that a rise in temperature would benefit C₄ weeds but not the rising CO₂ levels.