Effects of Chromium on Enzymatic/Nonenzymatic Antioxidants and Oxidant Levels of Portulaca oleracea L.

Purslane(Portulaca oleracea L.) is a local plant in Iran that can easily breed. Chromium is a heavy metal that causes toxicity for the growth and development of plants. To study the effects of  potassium dichromate on growth, efficiency of photosystem II (Fv/Fm), cell membrane stability index (MSI), indexes of oxidative stress and antioxidant properties of purslane, an experiment was done in a completely randomized design of five levels (0, 25, 50, 75 and 100 ppm Cr per kg of soil) in  a greenhouse condition. After 60 days, the effect of different levels of chromium on growth parameters, Fv/Fm, MSI, total phenolic compound, flavonoid, H2O2 and malondialdehyde content and antioxidants enzymatic activity (catalase, peroxidese and ascorbate peroxidase) was assayed. Along With increasing concentrations of chromium, the malondialdehyde (MDA) and H2O2 was increased, and followed by the enzymatic and nonenzymatic antioxidant compounds (except APX) was increased to compensate the effect of oxidant compounds. But, Heavy metal negatively affected growth parameters such as dry weight and length of root and shoot, Fv/Fm and MSI in contaminated plants. Therefore, the destructive effects due to chromium stress with increases the activity of enzymatic and non-enzymatic antioxidant system was minimized. It was noted that accumulation of chromium in the roots was higher than the shoots of the plants under treatment, significantly. Based on these results, purslane can be introduced as a good candidate for tolerance to chromium.