Root water uptake by corn under conjunctive water and salinity stress

Fluctuations in soil moisture and salinity would often result in variation of root water uptake. In this study, separate and conjunctive effects of water and salinity stress were investigated for water uptake from two separate layers. Two levels of salinity (ECe) namely 1.0 and 3.8 dS/m and two levels of depletion of 30 and 60% for the available water were selected for this study. Each layer combined of a salinity level and a level of depletion of available water. Experiments were conducted in corn under open field conditions. For this reason, 16 treatments with 3 replications, and total of 48 lysimeters were selected. Soil profile was divided into two layers of 32 (up) and 48 cm (down). The uppermost layer layer was irrigated from surface irrigation method while the lower layer with a subsurface irrigation technique. Results showed that, the maximum water uptake appeared in layers with higher moisture contents and lower salinity levels. Lowering of water uptake in the upper layer could be compensated by lower layer to some degrees. In some treatments, even though water uptake was not compensated, however an increase in water stress in one layer resulted in higher water uptake in the other one. Adjustment of crops to new stress conditions resulted in the maximum uptake to be from the layer with minimum stress. This study revealed that compensation of water uptake occurs when adjacent layer would experience no stresses.