Effect of Cadmium Levels on Seed Germination and Seedling Growth of Spinach (Spinacia oleracea) Under Salinity Stress

Cadmium is highly toxic heavy metal. Soil factors such as pH, caution exchange capacity, CaCO3 content and salinity have a significant influence on Cd uptake by plants. Moreover, soil salinity has a great impact on crop yield in Iran. Therefore, the effect of four salt levels (0, 45, 90, 180 mM) of NaCl solutions and four concentrations (0, 15, 30, 60 ppm) of Cadmium sulfate solutions on seed germination of spinach was studied in two separate experiments. Treatments were arranged in a factorial manner in base of completely randomized design with four replications. The most seed germination percentage decreased significantly with increasing after 180mM NaCl concentration under levels of Cd. Increased salt concentration caused a decrease in germination percentage and rate. In comparison with the control treatment, the lowest germination rate values determined at 180 mM NaCl salinity and 60 ppm Cd. Shoot and root length was reduced significantly with a rise in NaCl and Cd levels. Cd concentration had a more depressing effect on the root than on the shoot growth. Interactive effects between Cd and NaCl on dry weight and root length was significant. According to this study the interactive effect of both stresses were more than additive.