Abstract : Effect of nitrogen rates (1.0 g, 2.0 g N per pot) on magnesium concentration and uptake of Mg by aboveground phytomass of spring barley (variety Kompakt) and grain yield was investigated in 3-year pot experiment. Plants were grown under optimum moisture regime and drought stress was induced during growth stage of tillering, shooting and earing, respectively. Before and after respective stress period the plants were grown under optimal water regime.Ageing of the plant cover caused a decrease of Mg concentration in dry matter of aboveground phytomass. Fertilization of barley by nitrogen reduced the magnesium concentration in dry matter in all investigated growth stages (except 1 g N at tillering) at optimum water regime in comparison with unfertilized control treatment. Under stress conditions the situation was quite different when N fertilization tended to increase Mg concentration in DM. In oposition to Mg concentration, uptake of Mg by aboveground phytomass was increasing by ageing of plant cover in both fertilized and unfertilized treatments with maximum in growth stage of earing. Fertilization with nitrogen increased amount of up-taken magnesium several times comparing to control treatment under optimum water regime. Drought stress adversaly influenced Mg uptake, especially in fertilized treatment, where it decreased by 25-50% in comparison to uptake by plants grown under optimal water regime.

Key words: drought stress, nitrogen nutrition, growth stages, magnesium concentration, uptake of magnesium

Presentation: oral