Excess manganese effects on pigments of Mentha spicata at flowering stage

Abstract

Spearmint (Mentha spicata L.) plants were grown in a greenhouse in a nutrient solution containing manganese (Mn) concentrations varying between 9 μM and 15.75 μM until the flowering stage. The rates of chlorophyll and carotenoid contents were similar for treatments up to 13.5 μM, followed by a statistically significant increase onwards. Chlorophyll a and total carotenoids reduced gradually with increasing Mn concentrations, showing statistically significant differences in the last treatment (15.75 μM Mn) Anthocyanin contents increased gradually and steadily with increasing Mn concentrations. Accumulation of Mn in Mentha spicata roots was greater than shoots, indicating significant metal immobilization by the roots. The main conclusion is that Mn accumulation starts to be toxic as concentration of Mn increases.

Keywords:

• Mentha spicata
• excess manganese
• flowering stage
• anthocyanin
• chlorophyll