This publication is a collection of 14 research articles describing the work and achievements made by the participants of an IAEA Coordinated Research Project. Roots play a critical role in the efficient uptake of water and nutrients from the soil through adaptation of their architecture, construction plasticity, specialized structures, physiological responses and beneficial relationships with microorganisms. Roots also serve as storage organs for carbohydrates, they anchor plants in soil and may act as perennating structures that last for many years. However, information on the genetic analysis of root traits is scarce, and few characterized root mutants of crop plants are available. This publication covers topics including: methodologies for evaluating root structure and function, induced root mutants, and molecular genetic and physiological analysis. It provides a basis for the generation, selection and use of root mutants in crop improvement programmes.