Lead Phytotoxicity Induced Changes in Biochemical Markers in Germination and Seedlings in Durum Wheat Triticum durum Desf. Cv.Vitron and Gta

Among the heavy metals most commonly found on land, lead is a strongly represented pollutant in soil and sediments. It is easily absorbed and accumulated in different parts of plants. On the macroscopic scale, lead causes unfavorable effects on plants. First and in the event of excess, it may exert toxicity affecting several stages of germination development in leaf formation and root elongation in the early stages of development. The effect of lead on two varieties of durum wheat Triticum durum cv Gta and Vitron have been analyzed on germination under laboratory conditions. The objective is to determine the influence of lead on (i) germinal parameters and (ii) the stress physiological markers. The experiment was set up in a completely randomized design with 3 replications of 20 seeds per variety, including 4 concentrations of Pb(NO₃)₂ (0, 320, 430 and 660 ppm) on the germination. Average ambient temperature was 22°C, the humidity was 32% and photoperiod light/dark was 16/8 h. The obtained results showed a real sensitivity of germination to lead. Indeed, it was noted a total absence of germination of the two varieties in all seeds treated with the highest concentration. The treatment of seeds by the increasing doses of lead decreased the germinative faculty considerably, the content of pigments and disrupted the cellular metabolism, the proteins, the proline and glutathione levels. These results indicated that lead stress caused a decrease in germinal parameters and significant impairment of cell biochemical markers. Such effect was inversely proportional to the doses used. It was also noted that the Gta variety was less sensitive to lead toxicity than Vitron.