Development of a model estimating root length density from root impacts on a soil profile in pearl millet (Pennisetum glaucum (L.) R. Br). Application to measure root system response to water stress in field conditions

• Published in: PloS one 2019, Vol.14 (7), p.e0214182-e0214182
• Main Authors: Faye, Awa, Sine, Bassirou, Chopart, Jean-Louis, Grondin, Alexandre, Lucas, Mikael, Diedhiou, Abdala Gamby, Gantet, Pascal, Cournac, Laurent, Min, Doohong, Audebert, Alain, Kane, Aboubacry, Laplaze, Laurent
• Format: Article
• Language: English
• Subjects: Adaptation; Agricultural management; Agricultural practices; Agricultural production; Agriculture; Arid regions; Biology and Life Sciences; Breeding; Cereals; Climate change; Computer architecture; Density; Drought; Droughts; Ecology and Environmental Sciences; Environmental factors; Environmental impact; Environmental management; Food security; Life Sciences; Millet; Models, Biological; Parameter identification; Pennisetum - anatomy & histology; Pennisetum - physiology; Pennisetum glaucum; People and Places; Phenotypes; Plant growth; Plant Roots - anatomy & histology; Plant Roots - physiology; Planting density; Potash; Roots; Semi arid areas; Soil - chemistry; Soil depth; Soil fertility; Soil layers; Soil profiles; Soil properties; Stress, Physiological; Vegetal Biology; Water - metabolism; Water shortages; Water stress
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0214182

Pearl millet is able to withstand dry and hot conditions and plays an important role for food security in arid and semi-arid areas of Africa and India. However, low soil fertility and drought constrain pearl millet yield. One target to address these constraints through agricultural practices or breeding is root system architecture. In this study, in order to easily phenotype the root system in field conditions, we developed a model to predict root length density (RLD) of pearl millet plants from root intersection densities (RID) counted on a trench profile in field conditions. We identified root orientation as an important parameter to improve the relationship between RID and RLD. Root orientation was notably found to depend on soil depth and to differ between thick roots (more anisotropic with depth) and fine roots (isotropic at all depths). We used our model to study pearl millet root system response to drought and showed that pearl millet reorients its root growth toward deeper soil layers that retain more water in these conditions. Overall, this model opens ways for the characterization of the impact of environmental factors and management practices on pearl millet root system development.