Drought Stress in Cassava (Manihot esculenta): Management Strategies and Breeding Technologies

Drought stress is a major constraint to cassava productivity, especially in drought-prone regions. Although cassava is considered drought-tolerant, prolonged or severe water scarcity significantly reduces tuber yield, carbon assimilation capacity and overall plant growth. The development, selection and deployment of cassava genotypes with enhanced drought tolerance and water use efficiency (WUE) will help to achieve food security. The ability of cassava genotypes to maintain productivity under drought stress is enhanced by drought-responsive genes that regulate stress-related proteins and metabolites, contributing to stomatal closure, osmotic adjustment, antioxidant defense, and efficient carbon assimilation. Therefore, this comprehensive review aimed to document: (i) the effects of drought stress on cassava’s physiological, biochemical and agronomic traits, and (ii) the mitigation strategies and breeding technologies that can improve cassava yield production, drought tolerance and WUE. The key traits discussed include stomatal regulation, chlorophyll degradation, source–sink imbalance, root system architecture and carbon allocation dynamics. In addition, the review presents advances in genomic, proteomic and metabolomic tools, and emphasizes the role of early bulking genotypes, drought tolerance indices, and multi-trait selection in developing cassava cultivars with enhanced drought tolerance, drought escape and drought avoidance mechanism. Therefore, the integration of these strategies will accelerate the development, selection and deployment of improved cassava varieties, which contribute to sustainable productivity and global food security under climate change.