Effect of two Ni concentrations (10 and 200 μM) on growth, Ni accumulation, chlorophyll and proline contents, relative water content (RWC) as well as the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and glutathione S-transferase (GST) were studied in shoots of wheat plants. Treatments caused a considerable accumulation of Ni in the shoots. However, exposure of plants to 10 μM Ni did not lead to significant alterations in shoot growth except for a slight increase in fresh mass. The other parameters studied were not affected by treatment of plants with 10 μM Ni. In contrast, 200 μM Ni caused inhibition of shoot growth, a decline in RWC and chlorophyll content, accumulation of proline and occurrence of visible symptoms of Ni toxicity. The activities of SOD and CAT decreased in response to 200 μM Ni. Conversely, several-fold enhancements of POD and GST activities were observed following the 3 rd day of 200 μM Ni treatment.

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hydroponically grown wheat seedlings were treated with 50 µm ni and/or 15 µm Se. After a 7-day culture period, their growth parameters, ni, Se, fe, and mg contents, electrolyte leakage, photosynthetic pigment concentrations, and photochemical activity of photosystem ii were determined. exposure of wheat seedlings to ni alone resulted in reduction in the total shoot and root lengths, by 22% and 50%, respectively. Addition of Se to the ni-containing medium significantly improved the growth of these organs, compared to the seedlings subjected to ni alone. Application of Se decreased the accumulation of ni in shoots and roots and partially alleviated the ni-induced decrease in fe and mg concentations in shoots. electrolyte leakage increased in response to ni stress, but in shoots it was diminished by Se supplementation. exposure to ni led to a decrease in chlorophyll a and b contents and enhancement of chlorophyll a/b ratio, but did not influence the concentration of carotenoids. enrichment of the ni-containing medium with Se significantly increased chlorophyll b content, compared to the seedlings treated with ni alone. Photochemical activity, estimated in terms of the maximum quantum yield of photosystem ii, decreased in response to ni treatment but was significantly improved by simultaneous addition of Se. results of our study suggest that alleviation of ni toxicity in wheat seedlings by Se supplementation may be related to limitation of ni uptake.

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