How rhizosphere may affect nutrient uptake under drying soil condition

In this study, the effect of mucilage a gel like components released by roots on the diffusive transport of nutrient in soil was investigated. It was hypothesized that mucilage by keeping soil near the roots wetter and acting as a hydraulic bridge between soil particles could avoid a big drop in diffusion coefficient of nutrients as soil dries and help plants to better access nutrients at dry condition. Comparing the diffusion coefficients obtained from rhizospheric soil (soil treated with mucilage) and bulk soil showed that at the same water potential the diffusion coefficients were greater in the rhizospheric soil. Thereafter, the effect of mucilage on concentration of nutrients during a drying and rewetting cycles was evaluated. To this end, transport of nutrients in soil was numerically simulated by solving a diffusion-convection equation. The results showed that at the early stage of a drying cycle the presence of mucilage in the rhizosphere could favor a higher concentration of nutrients at the root surface. Interestingly at the late stage of a drying cycle presence of mucilage delayed an expected buildup of concentration at the root surface by avoiding a big drop in diffusion coefficient of nutrients.

Keywords:

Nutrient uptake , Mucilage , Rhizosphere , Salinity stress