Effect of N-fertilization and abiotic conditions on nitrate reductase activity in winter barley leaves

anglais. In small-plot nutritional experiment the effect of nitrogen fertilizing and impact of abiotic conditions (air temperature, precipitation and soil moisture) on nitrate reductase activity (NRA) in winter barley (varietes of Barcelona and Babylone) were investigating during one experimental year. In autumn, constant rate of NPK pure nutrients including 30 kg N per ha was applied before seeding. There were investigated 2 treatments: control treatment (unfertilized with N) and treatment fertilized with nitrogen each 4 times repeated. Early in spring regeneration fertilizing of winter barley was performed using LAD (ammonium nitrate with dolomite) in rate which was calculated on the basis of inorganic nitrogen content analyses of soil and in advance determined required N-level of 100 kg N per ha in soil. The winter barley leaves were analysed in six different growth stages for NR activity in dependance on nitrogen fertilization and soil moisture. Humidity of soil, air temperature, and precipitation were monitored during growing season. Effect of relative water content (RWC) on nitrate reductase activity in barley leaves was also investigated. From the viewpoint of NRA higher values were measured with variety of Babylone which were statistically significant in comparison with those of Barcelona under both fertilized and unfertilized conditions. Fertilization of barley with nitrogen increased NRA in both varieties in most of investigated growth stages. However, on the course of the whole growing season the effect of nitrogen fertilization on NRA was not statistically significant. In majority of investigated growth stages NRA values were increasing in accordance with increasing precipitation and air temperature in both examined varieties as well as under both fertilization treatments.

slovaque. V maloparcelovom pokuse s ozimným jačmeňom bol sledovaný vplyv dusíkatého hnojenia a agrometeorologických prvkov na aktivitu nitrátreduktázy v listoch jačmeňa ozimného. Pri dvoch odrodách (Babylone a Barcelona) boli sledované 2 varianty výživy v 4 opakovaniach. Kontrolný variant nebol hnojený dusíkom. V druhom variante bolo uskutočnené dohnojenie dusíkom na úroveň 100 kg N/ha pre každú odrodu. Počas vegetácie bol odoberaný rastlinný materiál na analýzu aktivity nitrátreduktázy a RWC v rastových fázach: DC 24, DC 32, DC 49, DC 55, DC 79, DC 89. Na stanovenie aktivity NR bola použitá metóda podľa Jaworski (1971). Z hľadiska aktivity enzýmu NR sa lepšie prejavil genotyp reprezentovaný odrodou Babylone, pri ktorej boli namerané hodnoty NRA štatisticky preukazne vyššie ako pri odrode Barcelona a to v podmienkach hnojenia dusíkom i bez hnojenia. Vo väčšine sledovaných rastových fáz hnojenie dusíkom zvyšovalo NRA pri obidvoch odrodách. Avšak v diapazóne celej vegetačnej doby nebol efekt hnojenia dusíkom na aktivitu nitrátreduktázy štatisticky preukazný. Aktivita nitrátreduktázy sa vo väčšine rastových fáz zvyšovala so stúpajúcimi zrážkami a atmosférickou teplotou (a naopak) pri obidvoch sledovaných odrodách a variantoch hnojenia.