Effect of cadmium and lead on morpho-physiological traits and Photosynthesis of ‎sweet basil (Ocimum basilicum L.)‎

The present research was conducted in order to evaluate the effects of different amounts of cadmium (Cd) and lead (Pb) on the morpho- physiological and biochemical aspects of sweet basil. Pre-treatments of the soil with different concentrations of Cd and Pb was applied two months before starting the experiment in the greenhouse, and then seeds were sown in pots containing contaminated soil, under greenhouse conditions. The results showed that application of cadmium and lead have led to significant changes in morphological traits and reduction in physiological and quality traits including number of lateral shoots, flowering intensities and stem diameter. By increasing concentrations of Cd from 0 to 20 mg. kg-1 soils, the amount of basil cadmium from 0.71 to 3.6 mg. g-1DW and with increasing concentrations of Pb from 0 to 400mg. kg-1 soil, the amount of basil Pb from 0.93 to 4.95 mg. g-1DWwas increased. Different levels of both heavy metals have resulted in significant reduction of SPAD value (22.95 to 13.98) as well as in the amount of chlorophyll a (0.755 to 0.333 mg. g-1 FW) chlorophyll b (0.330 to 0.125 mg. g-1 FW) and carotenoids (0.228 to 0.095 mg.g-1 FW) and photosystem II in chloroplasts (0.834 to 0.422) decreased compared to control plants. According to the increase of Cd and Pb in the plants is harmful and associated with the serious human health, therefore preventing culturing vegetable crops in the heavy metal contaminated soils should be considered.