The Effect of Cadmium on Physiological Indices, Growth Parameters and Nutrient Concentration in Tomato in Soilless Culture

In order to determine the effects of cadmium on growth, physiological parameters, and nutritional elements’ concentration in tomato organs in a soilless system, an experiment was conducted in greenhouse of Isfahan Agricultural and Natural Resources Research Center in 2008 with a complete randomized block design with two treatments and 6 replications. The treatments were nutritional solutions of Hoagland with and without cadmium (20 µM). The measured indices included: RGR, NAR, RLGR, LAR, SLA, LWR, LWCA, length of the stem, fresh and dry weight of root and shoot, amount of sugar, photosynthetic pigments, and concentration of nitrogen, potassium, phosphorous, calcium, magnesium, iron, zinc, copper, manganese, and cadmium in root, stem, leaves and fruit. The results showed that cadmium (20 µM) had significant effects on some measured growth indices. Growth parameters such as RGR, NAR, RLGR, Ls, RDW, RFW, SFW and SDW decreased 13.3, 19.1, 13.3, 18.8, 59.5, 58.7, 53.9 and 65.3%, respectively, and SLA increased 12.2%. But physiological parameters were not significantly affected by cadmium. The Cd concentration in all organs increased except fruit, compared with control which was Cd free. High cadmium concentration had significant effects on concentration of Mn and Cu in the root, Mn and P in the stem and Mn in the leaves. Concentration of Mn increased 5.3 and 87.6% in the leaves and stem, respectively, while it decreased 58.4% in the root. Concentration of P increased 33.3% and Cu increased 2times more in the stem. However, Ca concentration decreased 76.7% in the fruit, compared with the control. In conclusion, it is not recommended to grow tomato in the soils with high Cd concentration (polluted soil) because of its negative effects on tomato growth.