Methods to estimate changes in soil water for phenotyping root activity in the field

• Published in: Plant and soil Vol. 415; no. 1-2; pp. 407 - 422
• Main Authors: Whalley, W.R., Binley, A., Watts, C.W., Shanahan, P., Dodd, I.C., Ober, E.S., Ashton, R.W., Webster, C.P., White, R.P., Hawkesford, M. J.
• Format: Journal Article
• Language: English
• Published: Cham Springer 01-06-2017; Springer International Publishing; Springer Nature B.V
• Subjects: Biomedical and Life Sciences; Drying; Ecology; Electrical resistance; Electromagnetic interference; Excavation; Genetic aspects; Inductance; Life Sciences; Methods Paper; Moisture content; Observations; Penetrometers; Phenotypes; Phenotyping; Plant Physiology; Plant Sciences; Plant-soil relationships; Roots; Soil moisture; Soil profiles; Soil Science & Conservation; Soil water; Soils; Tillage; Water content; Water depth; Water resistance; Water uptake; Wheat; EMI; Penetrometer; Soil water profiles; Roots; ERT; Phenotyping
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-016-3161-1

Background and aims There is an urgent need to develop new high throughput approaches to phenotype roots in the field. Excavating roots to make direct measurements is labour intensive. An alternative to excavation is to measure soil drying profiles and to infer root activity. Methods We grew 23 lines of wheat in 2013, 2014 and 2015. In each year we estimated soil water profiles with electrical resistance tomography (ERT), electromagnetic inductance (EMI), penetrometer measurements and measurements of soil water content. We determined the relationships between the measured variable and soil water content and matric potential. Results We found that ERT and penetrometer measurements were closely related to soil matric potential and produced the best discrimination between wheat lines. We found genotypic differences in depth of water uptake in soil water profiles and in the extent of surface drying. Conclusions Penetrometer measurements can provide a reliable approach to comparing soil drying profiles by different wheat lines, and genotypic rankings are repeatable across years. EMI, which is more sensitive to soil water content than matric potential, and is less effective in drier soils than the penetrometer or ERT, nevertheless can be used to rapidly screen large populations for differences in root activity.