Impact of heat stress on nutritional status of staple crop vs. millets: A review

Abstract

Climate change and global warming have led to increased heat stress (HS), significantly impacting agricultural productivity and nutritional security. Staple crops such as rice, wheat and maize are particularly vulnerable, with elevated temperatures disrupting key physiological processes, including seed germination, photosynthesis, pollination and grain filling. HS causes severe metabolic imbalances, oxidative stress and phytohormone disruptions, ultimately reducing crop yield and grain quality. These challenges pressurize to identify heat-tolerant crop alternatives for sustaining global food security. Millets have emerged as a strategic solution due to their inherent resilience to abiotic stresses, including HS. These C4 plants possess unique morphological, physiological and biochemical adaptations, such as deep root systems, osmoprotectant accumulation, antioxidant enzyme activity and stress-responsive gene regulation, which enhance their thermotolerance. Unlike major cereals, millets maintain productivity under extreme temperatures, making them a viable alternative in climate-smart agriculture. Genetic advancements, including molecular breeding, transcriptomics and CRISPR/Cas9-based genome editing, offer potential strategies to further improve millet varieties for enhanced heat resilience and nutritional quality. This review explores the physiological, metabolic and molecular responses of staple crops and millets to HS, highlighting the advantages of millet-based agricultural systems. By integrating advanced biotechnological tools with traditional breeding methods, millets can be optimized for improved yield and climate adaptability. Intensifying the frequency of heat waves, promoting millet cultivation can play a pivotal role in mitigating global food insecurity, ensuring sustainable agricultural production and enhancing nutritional security in the phase of climate change.