Climate Change and Nitrogen-Fixing Legumes: Investigating Stress-Modulated Dynamics of Carbon Fixation and Root...

In the Anthropocene era, climate change is increasingly subjecting the crops to overlapping abiotic stressors such as drought, elevated temperatures, and air pollution, thereby disrupting their physiological integrity and functional performance. This review synthesises current knowledge on responses of N₂-fixing plants to such stressors, focusing on core physiological processes and symbiotic nitrogen fixation via nodulation. The intricate interdependence between these traits is explored through the lens of altered source-sink relationships, which are highly sensitive to multifactorial environmental perturbations. A key emphasis is placed on the emerging concept of multi-stress interactions, where the convergence of abiotic stressors leads to nonlinear, often compounding effects on plant metabolism, growth, and resource allocation. The modulatory role of elevated atmospheric CO₂ (carbon fertilisation effect) is also examined, particularly in enhancing photosynthetic assimilation, and sustaining nitrogen-fixing potential under stress. By identifying critical knowledge gaps and integrating physiological, biochemical, and ecological insights, this review provides a holistic framework to understand legume function under compounded climate threats. Such understanding is pivotal for breeding climate-resilient legumes that not only withstand abiotic stresses but also sustain yield and soil health. This discourse directly contributes to Sustainable Development Goals (SDGs), notably SDG 2 (Zero Hunger) and SDG 13 (Climate Action), by highlighting the role of legumes in securing global food systems and ecological resilience in the face of climate uncertainty.