Abstract: The aim was to explore the toxic effects of lead and chromium stresses on wheat and the influence of them on wheat proline. Treating wheat with different concentrations of lead and chromium was used to study the effects of single lead and chromium stress or combination of them on the proline content in wheat seedlings and wheat seed germination. The results showed that the seed germination rate, seedling height, root length, fresh weight and dry biomass all decreased under lead and chromium stresses in both single and combination. The proline content in each treatment group increased comparing with that in the control group at 1 d after treatment, especially under combined 100 mg/L Pb +100 mg/L Cr stress, the proline content increased 32.81% compared with the control. The proline content in the wheat seedlings treated with 100 mg/L Cr, 50 mg/L Cr, 200 mg/L Pb +100 mg/L Cr and 100 mg/L Pb +100 mg/L Cr showed a significant increase by 3 d, 5 d, 7 d after treatment when compared to the untreated control. No significant changes were observed for proline content in the other treatment groups. In conclusion, lead and chromium stresses inhibited wheat seed germination and seedling growth, and increased proline content in wheat. Therefore, it is suggested that the proline content in wheat may be used as one of the indicators to monitor lead and chromium stress.

Key words: lead, chromium, seed germination, proline, toxic effect