Impact of climate change on soybean and associated weed interactions

Soybean is an important oilseed crop, known to be fourth most cultivated crop globally, contributing to approximately 53% of total oil production. As a rainfed crop, soybean is particularly susceptible to the impacts of climate change. Climate change is expected to result in higher temperatures, elevated CO2 levels and altered rainfall pattern. As per IPCC Synthesis Report 2023, climate change may increase global temperatures by 1.5°C between 2021 and 2040 under high-emission scenarios. Without substantial mitigation efforts, the consequences could be catastrophic, leading to a 3.6-4.4°C rise in global temperatures and CO2 concentrations could rise to levels 2-4 times higher than those recorded in the past 0.8 million years, resulting in unprecedented climate changes. This climate change (elevated CO2) is found to have a positive impact on soybean seed yield (increase 32-37%) under weed-free conditions, however, under weedy condition seed yield of soybean may be reduced by 30% by C3 weeds and 45% by C4 weeds. Thus, C4 weeds are more competitive to C3 crops such as soybean under climate change condition. Elevated temperature was found to have more direct and positive impact on growth of most of the weed species, while it negatively impacted the soybean growth and yield parameters. However, interaction effect of CO2 and temperature was beneficial to both weeds and soybean. Apart from this, interaction of rainfall and temperature play a critical role in soybean productivity, where the simulation study advocates that increase in 1°C temperature with rainfall remaining constant, leads to a decline in productivity by 10-15%. Anticipating potential damage from weed to soybean is crucial for formulating effective and sustainable weed management strategies. Therefore, it is vital to address soybean-weed interactions and weed management in the context of climate change, as there has been inadequate research conducted in this area.