title: Root-soil air gap and resistance to water flow at the soil-root interface of Robinia pseudoacacia.
abstract: During periods of water deficit, growing roots may shrink, retaining only partial contact with the soil. In this study, known mathematical models were used to calculate the root-soil air gap and water flow resistance at the soil-root interface, respectively, of Robinia pseudoacacia L. under different water conditions. Using a digital camera, the root-soil air gap of R. pseudoacacia was investigated in a root growth chamber; this root-soil air gap and the model-inferred water flow resistance at the soil-root interface were compared with predictions based on a separate outdoor experiment. The results indicated progressively greater root shrinkage and loss of root-soil contact with decreasing soil water potential. The average widths of the root-soil air gap for R. pseudoacacia in open fields and in the root growth chamber were 0.24 and 0.39 mm, respectively. The resistance to water flow at the soil-root interface in both environments increased with decreasing soil water potential. Stepwise regression analysis demonstrated that soil water potential and soil temperature were the best predictors of variation in the root-soil air gap. A combination of soil water potential, soil temperature, root-air water potential difference and soil-root water potential difference best predicted the resistance to water flow at the soil-root interface.
authors.affiliation: Taihangshan Dongpo Forest Ecosystem Research Station, State Forestry Administration/Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China.
authors.forename: X P
authors.initials: XP
authors.lastname: Liu
authors.affiliation: Taihangshan Dongpo Forest Ecosystem Research Station, State Forestry Administration/Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China zhangwj@sjziam.ac.cn laly997@163.com.
authors.forename: W J
authors.initials: WJ
authors.lastname: Zhang
authors.affiliation: Taihangshan Dongpo Forest Ecosystem Research Station, State Forestry Administration/Key Laboratory of Agricultural Water Resources, Hebei Key Laboratory of Agricultural Water-Saving, Center for Agricultural Resources Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Shijiazhuang 050021, China zhangwj@sjziam.ac.cn laly997@163.com.
authors.forename: X Y
authors.initials: XY
authors.lastname: Wang
authors.affiliation: Key Laboratory of Mountain Surface Processes and Ecological Regulation, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China.
authors.forename: Y J
authors.initials: YJ
authors.lastname: Cai
authors.affiliation: Shanxi Academy of Forestry Sciences, Taiyuan 030012, China.
authors.forename: J G
authors.initials: JG
authors.lastname: Chang
mesh_terms: D008954:Models, Biological; D018517:Plant Roots / Q000378:metabolism; D058441:Rhizosphere; D031301:Robinia / Q000378:metabolism*; D012987:Soil / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000378:metabolism*
chemical_list: D012987:Soil; D014867:Water
keywords: Robinia pseudoacacia; root–soil air gap; soil–root interface; water flow resistance at the soil–root interface