Cadmium toxicity in garden cress (Lepidium sativum L.): germination and vegetative stage responses

Cadmium is a hazardous toxic element that adversely affects plant vegetative and reproductive processes. Garden cress (Lepidium sativum L.) is a fragrant and savory herb, widely consumed in human diets, particularly in salads. This study researched the responses of garden cress to Cd in two experimental setups: germination tests in Petri dishes and hydroponic treatments during the early vegetative stage. In the germination experiment, seeds were put in Petri dishes with filter paper, and treated with CdCl₂ solutions at 0, 25, 50, 100, 200, and 500 µM concentrations. The Petri dishes were kept in a controlled environment, and germination parameters, including germination percentage, germination index, radicle and plumule length, and fresh and dry weight of sprouted seeds, were recorded. Then, the hydroponic experiment was carried out, and germinated seedlings were transferred to a nutrient solution with the same Cd concentrations. At harvest, root-shoot length, fresh and dry weight were measured, later pigment and proline analyses were done. Cd treatments caused a slight, non-significant reduction in germination percentage. While no marked changes were observed in plumule length, a significant reduction in radicle length was detected, particularly at doses of 100 µM and above. The fresh weights of germinated seeds showed a non-significant decreasing trend, whereas their dry weights increased and their water contents decreased significantly. In the hydroponic experiment shoot fresh and dry weights were markedly reduced under Cd treatments. Although no significant changes were detected in root fresh and dry weights, root length was found to be significantly reduced. Pigment contents slightly increased at low Cd levels but declined significantly at ≥100 µM. Proline accumulation increased progressively, reaching the highest level at 500 µM. The results indicate that Cd exposure induces stress in garden cress by adversely affecting germination, growth, and physiological processes.