Study of the effect of cadmium accumulation on some physiological and biochemical characteristics of basil plants (Ocimum basilicum L.)

Basil (Ocimum basilicum L.) is a high using edible and medicinal plant. As some places of Zanjan province in which basil plant is cultured are contaminated by heavy metals, such as toxic cadmium metal, a research for analyzing Cd accumulation and its effects on some physiological and biochemical traits of this plant was performed. Seeds were cultured in plastic pots containing perlite and Hoagland’s culture medium in a hydroponic condition. After three-weeks plantlets with enough growth were treated by different concentrations of Cd including: 0 (control), 2, 4 and 8 mM for two weeks. Results showed that, root and shoot dry weight, root and shoot length as well as chlorophyll a and b and carotenoids contents and leaf area in all Cd treatments were decreased in compare to the control plants. 8 mM Cd treatment showed the maximum decrease in all above traits. The content of soluble proteins, proline and soluble sugars of root and shoot of treated plants increased at all Cd treatments in compare to control plants. The activity of catalase enzyme was decreased in roots and shoots of Cd treated plants however; the activity of peroxidase was increased at all Cd treatments. The concentration of Cd in roots of treated plants was about three times higher than that of shoots at 8 mM Cd concentration. As a conclusion, basil plants showed a little tolerance against Cd heavy metal by increasing of their peroxidase activity, proline, soluble sugars and protein contents however, they are not able to prevent Cd penetration to their roots and specially shoots which make them to be contaminated.