Cultivating of Rubia tinctorum L. As An Efficacious Method to Reclamation of a Saline-Sodic Soil

To reclamation of salt-affected soils, in addition to using chemical amendments, phytoremediation also can be effective. This experiment was conducted in the columns filled with a saline-sodic soil to evaluate the effectiveness of cultivating Rubia tinctorum to improving soil characteristics. There were 7 treatments with 2 replications including 3 plants (Sesbania acuelata, Rubia tinctorum and Cynodon dactylon), 3 chemical treatments (Gypsum in 2 levels and sulfuric acid) and a control. Chemical treatments 1 month after applying to the soil, plants 5.5 months after cultivation and the control were leached with 41 liters of water. After leaching, some of soil properties including saturated hydraulic conductivity (Ks), mean weight diameter (MWD), electrical conductivity of saturation extract, sodium adsorption ratio (SAR) and the amount of drainage water soluble sodium were measured. The results showed that Rubia tinctorum was most effective plant in improving soil physical properties, so that the highest Ks (20.5×10-5cm s-1) and MWD (0.92) is related to that and lowest values is related to the control (2.4×10-5cm s-1 and 0.2). The most sodium leaching from soil columns was related to Rubia tinctorum (55.37 g) which was 3 times greater than control. All of the treatments also significantly decreased SAR compared to the control.