Short-term application of melatonin can partially restore the mineral balance in heavy-metal treated Amaranthus cruentus var. ‘Pribina’

An excess amount of particular metal ions can cause nutrient imbalance and inhibit plant growth and development. In this preliminary study, the short-term (2 weeks) and long-term (6 weeks) application was carried out to investigate the potential ameliorative effect of foliar application of melatonin and reveal the changes in ion profiles of grain amaranth Amaranthus cruentus var. ‘Pribina’ treated with Cd, Zn, and Mn. Nine elements (Ca, K, Mg, Na, Cu, Fe, Cd, Zn, Mn) were examined using inductively coupled plasma optical emission spectrophotometry. Different ionomic responses were observed in root and shoot tissues. The results showed that Cu, K, Mn and Na were the most affected elements, which significantly changed after heavy metal applications. Application of Zn had the most prominent effect on the alternations in ion concentrations. In addition, short-term melatonin supplementation reduced Cd and Mn root-to-shoot translocation. No marked changes were recorded between short-term and long-term applications, indicating that short-term use is sufficient for restoring the mineral balance, albeit not for all elements.