Toward drought-resilient soybean genotypes integrating global socioeconomic constraints genetic mechanisms and breeding priorities

Abstract Soybean ( Glycine max (L.) Merr.) is an important crop for food security, nutrition, livestock feed and rural livelihoods in Tanzania, but recurrent drought threatens productivity in rainfed production systems. This systematic review synthesized global evidence on physiological, biochemical, genetic, molecular, breeding, agronomic and socioeconomic determinants of drought resilience in soybean, with particular emphasis on their relevance to Tanzania and Sub-Saharan Africa. Following PRISMA 2020 guidelines, we searched peer-reviewed literature published from 2015 to April 2026 in predefined bibliographic databases using data-extraction criteria. We included 190 studies and organized them into 12 thematic areas. The evidence indicates that soybean drought adaptation is a complex quantitative phenomenon involving coordinated changes in root development, plant water status, photosynthesis, osmotic adjustment, antioxidant defence, reproductive performance and stress-responsive signalling. Molecular and genomic studies have identified candidate genes, QTLs and genomic regions associated with drought-responsive traits, while breeding studies demonstrate the value of combining physiological selection with molecular approaches. However, the strength and transferability of reported effects vary with drought intensity, developmental stage, genetic background and target environment. Evidence is limited for Sub-Saharan Africa, where field validation, high-throughput phenotyping, genomic infrastructure and seed delivery remain constrained. The evidence supports a validation-first breeding strategy that combines adapted germplasm, physiological phenotyping, appropriate genomic tools, multi-environment evaluation and farmer-oriented selection. Strengthening breeding and phenotyping capacity, seed systems, and extension services will be essential to translate drought-resilience research into stable, farmer-accessible soybean productivity under climate variability.