Change in hydraulic properties of the rhizosphere of maize under different abiotic stresses

Root growth alters the rhizosphere thereby affecting root uptake of water and nutrients. However, the influence of abiotic stress on this process is poorly understood. In this study we investigated the effects of water and salinity stresses (both in isolation and combined) on maize (Zea mays L.). Seedlings were grown in pots packed with a loamy sand soil for two weeks and then subjected to water and salinity stresses, together with an unstressed control. After an additional two weeks, plants were removed from the pots and the soil aggregates adhering to the roots were collected and scanned using X-ray Computed Tomography. The ability of the aggregates to conduct water was calculated from pore-scale simulation of water flow using the lattice Boltzmann method. It was found that both water and salinity stresses reduced the permeability of the rhizospheric aggregates, although the reduction under salinity stress was more significant than under water stress. Combining water and salinity stresses reduced the permeability of the rhizosphere by one order in magnitude compared to the unstressed rhizosphere. Abiotic stresses work with root-induced activity to reshape the rhizosphere. As water and nutrients need to pass through the rhizosphere before being taken up by roots, understanding such rhizosphere changes has an important implication in plant acquisition of soil resources.