Rhizoeconomics: The roots of shoot growth limitations

The growth of terrestrial plants is primarily limited by edaphic factors such as drought, nutrient deficiencies, and mineral toxicities. Roots express an array of adaptive traits that help plants cope with these stresses, but such traits often incur significant costs, including direct metabolic costs, tradeoffs for contrasting resources, opportunity costs, and increased risks of biotic and abiotic stress. As an example, root cortical aerenchyma appears to improve crop growth under drought and low soil fertility by reducing the metabolic costs of soil exploration. Production of root cortical aerenchyma, however, may involve tradeoffs by reducing radial transport, mycorrhizal colonization, and by increasing disease susceptibility. A better understanding is needed of the full costs associated with specific root traits if we are to develop crops with better growth and yield in the stressful soil environments that increasingly dominate the earth's surface.