DYNAMIC ROOT RESPONSES TO WATER DEFICITS

Abstract

Water absorption is influenced by the geometric distribution of viable roots and the availability of water at root surfaces. Utilization of additional plant energy for the extensive and localized development of root systems is a high risk investment of carbon by the plant, especially during short-term water deficits. Nonuniform root distribution, resulting from root growth within networks of continuous soil macropores, reduces the efficiency of water absorption by minimizing contact between roots and increasing the geometric mean pathway of water from the bulk soil to the root. Root clustering in these soil niches causes greater intraspecific competition for the limited water, especially as soil water deficits develop more deeply within the soil profile. Current methods for quantifying and predicting plant root and soil water relationships are reviewed, and some research and modeling imperatives are presented.