The Effects of Magnetic Treatment On Seedling Growth, Nitrogen Metabolism, And Mineral Nutrient Contents In Populus×Euramericana 'Neva' Under Cadmium Stress

Background: The potted experiment was carried out to investigate the mechanism of nutrient metabolism and seedling growth caused by magnetic treatment (MT) following exposure to cadmium (Cd) stress. One-year-old seedlings of Populus×euramericana 'Neva' were treated with different Cd(NO3)2 solutions for 30 days. Properties of seedling growth and root morphology were promoted by MT under Cd exposure.Results: Contents of ammonium (NH4+-N), nitrate (NO3--N), and total nitrogen (TN) in leaves, also NH4+-N and TN in roots, were increased by MT combined with Cd-stress, although NO3--N content was decreased. Activities of nitrate reductase (NR), nitrite reductase (NiR), glutathione reductase (GR), and glutamate synthase (GOGAT) in leaves and activities of NR, GS and GOGAT in roots were stimulated by MT; conversely, NiR activity in roots was inhibited. MT improved the synthesis of cysteine (Cys) and glutamine (Gln) in leaves and reduced the contents of glutamic acid (Glu) and glycine (Gly), while contents of Cys, Glu, Gln, and Gly were increased in roots. (4) The contents of Ca, Mg, Fe, Mn, Zn and Cu were increased by MT under Cd stress in leaves, whereas content of K was reduced. In roots, contents of K, Ca, and Fe were increased by MT under Cd-stress, but the contents of Na, Mg, Mn, Zn, and Cu were decreased.Conclusions: Magnetization could regulate the uptake of mineral nutrients by roots and translocation from the roots to aboveground parts by affecting the root morphology. MT could also improve nitrogen assimilation and the synthesis of free amino acids by stimulating the activities of key enzymes.