Abstract
In pot experiments the high doses of nitrogen (3.50 g of NH4NO4 per one pot with 9.5 kg of sand) cause the increase of tillering intensity, leaf assimilatory area, water as well as chlorophyll (a+b) content, total and nitrate nitrogen content, and biomass increment of Italian ryegrass (tetraploid) plants. However, these doses do not effect: the nucleic acids content, number of stomata (per surface area unit of leaf blades), number of vascular bundles in leaves, and the intensity of 14CO2 uptake by these leaves.