Evaluation of Salinity Tolerance of Withania (Withania coagulans Dunal.) Based on Some Morphological and Physiological Indices

Withania (Withania coagulans Dunal.) is one of the most economically important plants endemic to Sistan and Baluchestan province in Iran.  This plant is used in landscape, pharmaceutical industries and stabilization of sand in desert areas. Salinity is one of the limiting factors of growth and geographical distribution of plants. This study was conducted to evaluate the effects of salinity stress (sodium chloride and potassium chloride) on some morphological and physiological characteristics of withania. The experiment was laid out based on a completely randomized design with 9 treatments and 4 replications under greenhouse conditions. Treatments were: control (without stress) and sodium chloride and potassium chloride in four levels (50, 100, 150, and 200 mM). The results showed that salinity stress significantly affected proline content, Ioninc leakage percentage, Fluorescence chlorophyll, shoot and root dry weight, root to shoot dry weight ratio, leave surface, root length and survival percentage (P≤1%). Mean Comparisons showed that the highest value of proline and Ioninc leakage percentage respectively 4.27 (μmol g-1 FW) and 45.56% were obtained at 200 mM of NaCl and The least value of proline and Ioninc leakage percentage were observed at control. Morphological indices showed more decline under NaCl treatment compared to KCl. so that, leave surface decreased at 200 mM NaCl (58.45 cm2) compared to 200 mM KC (69.70 cm2). Also, with increasing salinity stress, root to shoot dry weight ratio was increased. The maximum amount of root to shoot dry weight ratio (1.01) was obtained at 200 mM of NaCl. Our findings showed that the tolerance of withania to salinity stress was determined equal to 100 mM, while with increasing salinity stress to 200 mM, percentage of survival was decreased (70.38%) compared to the control. Therefore, based on the obtained results, in addition to the use in landscape, withania can be used in saline areas.