Response of nitrogen metabolism in lettuce plants subjected to different doses and forms of selenium

BACKGROUND: Currently, biofortification programmes are being carried out with selenium (Se), since it is an essential element for humans and its ingestion depends partly on a vegetable diet, this not being so for plants. In this sense, few studies have tested the effect that Se has on some of the main plant metabolisms, such as nitrogen (N) metabolism. Thus the aim of this study was to establish the effect of the application of different doses (5, 10, 20, 40, 60, 80 and 120 mu mol L(-1)) and forms (selenate and selenite) of Se on the reduction of nitrate (NO(3)(-)) and subsequent assimilation of ammonium (NH(4)(+)). RESULTS: The results showed an increase in all enzyme activities analysed (nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) and glutamate synthase (GOGAT)), especially with application of the selenite form, in addition to a decline in foliar NO(3)(-) concentration. CONCLUSION: Se applied in both forms increased N metabolism, with selenite inducing this physiological process more strongly, since it prompted a stronger activation of NR, GS and GOGAT as well as a greater concentration of total reduced N. (C) 2010 Society of Chemical Industry