Growth responses of Atriplex lentiformis and Medicago arborea in three soil types treated with saline water irrigation

Large amounts of industrial wastewater, often of high in salt content, are produced by urban activities or industries which require reuse or disposal and thus can be potentially used in agriculture to ease the pressure on freshwater supply for irrigation. At the same time, plant performance in the field may be determined not only by salt concentration per se but also by confounding effects associated with soil physical and chemical properties. The purpose of this study was to investigate the effect of saline water irrigation (0–16 dS/m range) on the performance of two plant species, Atriplex lentiformis (xero halophyte) and Medicago arborea (glycophyte) grown in three soil texture setups – (1) clay, (2) sandy loam and (3) sandy loam over clay (texture-contrast) – under glasshouse conditions. Both plant species yielded higher biomass in the clay texture compared to other soil texture setups under all irrigation treatments. There was no significant variation in chlorophyll fluorescence with salt treatments but stomatal conductance was significantly reduced (up to 70%) by salinity in M. arborea. Overall, leaf ion content (Na⁺ and Cl⁻) also increased with increasing salinity treatment in both plants, but significant effects were seen only in sandy loam soil for both species. Both osmotic effect and specific ionic toxicity impacted physiological performance in M. arborea while A. lentiformis plants were insensitive to both components of salt stress. Plant performance in the sandy soil was not as good as in clay, indicating that soil texture and structure may have a significant role in the salt stress process under saline irrigation.