Toward water-smart cereal production: a narrative review of agronomic, genetic, and digital innovations for water productivity and climate resilience

Cereal crops consume more freshwater than any other category of agricultural production, yet no recent review has quantitatively integrated agronomic, genetic, and digital water-smart innovations across the seven cereals most relevant to global food security: wheat (Triticum spp.), rice (Oryza sativa L.), maize (Zea mays L.), barley (Hordeum vulgare L.), sorghum (Sorghum bicolor [L.] Moench), pearl millet (Pennisetum glaucum [L.] R.Br.), and finger millet (Eleusine coracana [L.] Gaertn.). This narrative review addresses that gap by synthesizing 110 studies — retrieved through a PRISMA-inspired selection workflow and appraised on a four-dimensional quality rubric — across five intervention domains: deficit irrigation, soil-moisture conservation, drought-resilient varieties, precision agriculture and digital irrigation, and integrated water management. Quantitative pooled findings indicate that mild alternate wetting and drying in rice reduces irrigation water by ~23% with negligible yield penalty, whereas severe drying incurs a ~23% yield loss; deficit irrigation in wheat improves water productivity by ~7% but reduces yield by ~16%; and straw mulching raises cereal yields by 13–22% (pooled). IoT-based scheduling delivers meaningful but heterogeneous irrigation- water savings relative to calendar-based practice, although the cerealspecific evidence base remains thin relative to horticultural applications. The review’s principal contribution is the Genetics × Agronomy × Digital (G×A×D) integration framework, which maps these three intervention families onto the soil–plant–atmosphere–institution continuum and makes their combinatorial opportunities and institutional prerequisites explicit. The central critical conclusion is that the binding constraint on water-smart cereal production has shifted from the technical feasibility of individual interventions to the institutional, financial, and governance capacity required to combine them equitably, particularly in smallholder systems. Evidence for finger millet and for rainfed smallholder systems in sub-Saharan Africa remains notably thin and represents a priority gap.