EN
The subject of the paper is a discussion of the effect of plant nitrogen nutrition (its deficiency and surplus) on processes affecting photosynthetic productivity and total biomass and agricultural (or economical) yield production. Among others, attention was paid to the effect of nitrogen nutrition on chlorophyll and protein synthesis, as weil as on the rate of photosynthesis, photorespiration and dark respiration (process contributing to net photosynthesis) bringing about a rise in the ratio of true to net photosynthesis, which reflects photosynthetic productivity per dm² of assimilating area. The influence of nitrogen nutrition on the assimilating area, translocation and final accumulation of the photosynthate in the organs for agricultural usage is also discussed.