Effet des métaux lourds (zinc et cuivre) sur la germination et les paramètres morphologiques des plantules de tomate (Lycopersicon esculentum. Mill).

Abstract

Among the main pollutants generated by industrial activities, heavy metals such as zinc and copper pose particularly worrying problems. Indeed, these elements are inherently non-biodegradable. This work investigates the effects of zinc and copper on the germination and growth of seedlings of the important tomato species (Lycopersicum esculentum). For this purpose, different doses of a zinc and copper solution were used (0.05g/l, 0.1g/l, 0.3g/l, and 0.5g/l). The results of this experiment reveal some effects of zinc and copper at different concentrations on seed germination and the growth of young Lycopersicum esculentum seedlings. Based on the results obtained, it can be deduced that the 0.5g/l copper concentration severely affected germination kinetics, with a four-day germination delay and a germination percentage of only 20 %. However, the effect of zinc reduced the final germination percentage, with a maximum rate of 68% compared to 20% in grains treated with copper at a dose of 0.5g/l and with a GMT of 6.8 days. The vigor index showed a reduction starting at a concentration of 0.3g/l of zinc and copper; this effect was further accentuated at high zinc concentrations, reaching 18 and 12 in the presence of a copper concentration of 0.5g/l. Seedling height is significantly affected at high zinc and copper concentrations, and a severe decrease in seedling and stem growth is observed, while root length is not affected by the presence of different zinc concentrations of 0.05 and 0.5g/l. However, root growth is sensitive to high copper concentrations of 0.3 g/l. Under the influence of copper doses, a difference in seedling growth between the different doses compared to the control was detected, this difference becoming detectable from 0.05 g/l. Seeds treated with high zinc concentrations showed an overall positive effect on the germination process. However, increasing copper concentrations could cause negative or toxic effects.