Comparative study on some effects of exposure of wheat plants to three different antibiotics

Germinated wheat caryopses were planted on agar solidified nutrient solutions that were supplemented with three antibiotics (ampicillin, tetracycline and chloramphenicol, in separate experiments), each of them at two different concentrations: 4 mg.L-1 and 20 mg.L-1, respectively, alongside controls unexposed to antibiotics. Seven days after the initiation of the experiment, the young wheat plants were harvested and the length of their root and shoot was measured. Leaf samples were collected and used for the extraction and assay of chlorophylls and carotenoids content. The obtained results have shown that ampicillin exposure didn’t affect the analyzed parameters, while the exposure to tetracycline or chloramphenicol was followed by a marked, dose-dependent, inhibition of plant growth rate, compared to control plants. Lower contents of chlorophylls and carotenoids were also observed in the plants that were exposed to tetracycline and chloramphenicol, compared to unexposed ones. We concluded that besides the amount of antibiotic, its structure and mechanism of action influences phytotoxicity. Thus, on a toxicity scale inferred from the obtained results, chloramphenicol ranks first, followed by tetracycline and ampicillin.