Response of Two Mint Cultivars Peppermint (Mentha piperita L.) and Curly Mint (Mentha spicata var. crispa) to Different Levels of
Cadmium Contamination
Nizar A. Mohammed, Warheel N. Ali, Zeinab M. Younis,
Pashtiwan J. M. Zeebaree, Mohammed J. Qasim
The agricultural soils that are contaminated with heavy metals poses significant environmental challenges, impacting plant productivity and the safety of plant-based food and feed products. Cadmium (Cd) that is considered one of heavy metals enters the ecosystem by two sources natural and anthropogenic. Rising Cd level in edible plants has impact on human health. The primary objective of the present study was to investigate the influence of different levels of cadmium contamination in soil on the growth and chemical composition of two different mint cultivars, namely peppermint and curly mint as well as accumulation of Cd in mint leaves. The experiment was conducted using a randomized complete block design (RCBD) using three replications. Uniform rhizomes in weight were planted with a size of 17 cm in pots. After the rhizomes had developed to produce leaves, the plants were irrigated with different concentrations of cadmium in distilled water as solution (0, 15, 30, and 45 mg/kg), for control only distilled water was used. The results indicated that peppermint plants performed better than curly mint plants in terms of various vegetative and chemical parameters. On the other hand, the increased concentrations of cadmium from Zero to 45 mg/kg resulted in significant decrease in most morphological and chemical characters in both mint cultivars. The affected parameters were plant height decreased to (29.05 cm), fresh and dry vegetative weight (29.52-11.83 g), leaf area (190.1 cm2), number of leaves (31.17 leaf plant-1), total chlorophyll content (14.01 mg g-1 F.W), and carbohydrate content in the leaves (7.41 %) compared to the control. Nevertheless, it has been noticed that the percentage of volatile oil and the amount of volatile oil per plant increased when the soil was treated with 15 mg/kg of cadmium in both cultivars (1.537%) for peppermint and (1.340%) for curly mint. Additionally, the accumulation of cadmium in the leaves also increased to (0.165 mg/kg) after the soil was treated by 30mg/kg of cadmium comparing to the control. This means that when the mint plants obtained from areas contaminated with Cd have high concentration of Cd in there structure and have impact on health when they have been eaten.
Keywords: Cadmium, chemical constituent, mint plants, soil contamination, vegetative growth