TY  - JOUR
A1  - Cai, Gaochao
A1  - Tötzke, Christian
A1  - Kaestner, Anders
A1  - Ahmed, Mutez Ali
T1  - Quantification of root water uptake and redistribution using neutron imaging: a review and future directions
JF  - The plant journal
N2  - Quantifying root water uptake is essential to understanding plant water use and responses to different environmental conditions. However, non-destructive measurement of water transport and related hydraulics in the soil-root system remains a challenge. 
Neutron imaging, with its high sensitivity to hydrogen, has become an unparalleled tool to visualize and quantify root water uptake in vivo. In combination with isotopes (e.g., deuterated water) and a diffusion-convection model, root water uptake and hydraulic redistribution in root and soil can be quantified. 
Here, we review recent advances in utilizing neutron imaging to visualize and quantify root water uptake, hydraulic redistribution in roots and soil, and root hydraulic properties of different plant species. 
Under uniform soil moisture distributions, neutron radiographic studies have shown that water uptake was not uniform along the root and depended on both root type and age. For both tap (e.g., lupine [Lupinus albus L.]) and fibrous (e.g., maize [Zea mays L.]) root systems, water was mainly taken up through lateral roots. In mature maize, the location of water uptake shifted from seminal roots and their laterals to crown/nodal roots and their laterals. 
Under non-uniform soil moisture distributions, part of the water taken up during the daytime maintained the growth of crown/nodal roots in the upper, drier soil layers. Ultra-fast neutron tomography provides new insights into 3D water movement in soil and roots. We discuss the limitations of using neutron imaging and propose future directions to utilize neutron imaging to advance our understanding of root water uptake and soil-root interactions.
KW  - attenuation coefficient
KW  - convection
KW  - diffusion
KW  - radiography
KW  - root hydraulics
KW  - root water uptake
KW  - tomography
Y1  - 2022
U6  - https://doi.org/10.1111/tpj.15839
SN  - 0960-7412
SN  - 1365-313X
VL  - 111
IS  - 2
SP  - 348
EP  - 359
PB  - Wiley-Blackwell
CY  - Oxford [u.a.]
ER  -