Development of future crop varieties with efficient root systems for enhanced water and phosphorus uptake is essential for improving crop adaptation and hence food security. Root system architecture (RSA) traits that overcome low-water and low-phosphorus stresses are critical to maintaining structural and functional properties, and are considered the first-order targets in breeding programmes for rainfed environments. Modification of root system architecture could contribute to improvements of desirable agronomic and physiological traits such as biomass, yield, drought resistance, and tolerance to nutrient deficiencies. Advanced phenotyping, imaging, modelling and molecular biotechnologies offer promise in identifying RSA traits for efficient resource acquisition and adaptation to abiotic stresses. This review highlights the complexity and regulation of RSA in response to water and P stresses.