Response of Nitrogen Metabolism in Pak-choi Plants Treated with Different Sodium Selenate (Na₂SeO₄) Concentrations

抄録

Currently, biofortification breeding programs are being conducted to increase the selenium (Se) content of crops. Se is an element essential to humans and is mostly acquired via consumption of vegetables. However, the effects of Se on the main plant metabolisms such as nitrogen metabolism are unclear. The main objective of this study was to determine the effect of the application of different concentrations of Se (10, 20, and 30 μM) as Na₂SeO₄ on nitrogen metabolism in Pak-choi grown hydroponically. Supplemental Se increased all enzyme activities analyzed, including nitrate reductase (NR), glutamine synthetase (GS), and glutamate synthase (GOGAT). In 20-μM Se treatment of two cultivars, the fresh weight was significantly increased and the foliar NO₃⁻ content was significantly decreased. Compared to the control, the data on Se treatments showed stronger activations of NR, GS, and GOGAT, as well as greater concentrations of total ammonium, amino acid, and protein, and a higher nitrogen use efficiency, resulting in increased biomass production. This suggests the mechanism of Se applied to Pak-choi to decrease NO₃⁻ content was due to increasing nitrogen metabolism and protein synthesis to biomass.