Chromium is the seventh most abundant element on the earth's crust. Cr+3 is an essential micronutrient for the health of man and animals while Cr+6 is extremely toxic. To study physiological response and phytoaccumulation of Cr+3 and Cr+6 by Petroselinum crispum, seedlings were grown in hydroponic culture containing different levels of Cr+3 (0.1, 0.25, 0.75, 1, 1.5, 2 and 3 mg/l) and Cr+6 (0.1, 0.25, 0.5 and 0.75 mg/l). After 5 and 3 weeks treatment with Cr+3 and Cr+6, the effects on growth, chlorophyll a and b content and concentrations of Ca+2, K+, Na+, Cr+3 and Cr+6 in the roots and shoots were studied. The results showed that increasing of Cr+3 to 3 and 2-3 mg/l caused statistically significant decreasing of dry weight in the root and shoot, respectively. It was the same for Cr+6 but at 0.75 mg/l. Length of the roots and shoots decreased significantly at 0.75 mg/l to 3 mg/l Cr+3 and 0.75 mg/l Cr+6. Chromium reduced significantly total chlorophyll, chlorophyll a and b at 3 mg/l Cr+3 and all treatments of Cr+6 except 0.1 mg/l. Ca+2 and K+ concentrations in the roots and shoots were also affected by chromium. Significant decrease of Ca+2, K+ and Na+ was observed in 2-3 mg/l Cr+3 and 0.5-0.75 mg/l Cr+6, 3 mg/l Cr+3 and 0.25-0.75 mg/l Cr+6 and 3 mg/l Cr+3, respectively. Accumulation of chromium in both roots and shoots enhanced with increasing levels of Cr+3 and Cr+6 in the culture. Roots accumulated more chromium than the shoots. Visible toxicity symptoms including shrunk leaves, stunted roots and shoots growth, reduced number and surface of leaves and chlorosis of the young leaves were observed at the highest level of chromium supplied (3mg/lCr+3 and 0.75 mg/lCr+6). Generally, Cr+6 indicated toxicity symptoms at lower concentrations and shorter time than Cr+3.

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