EN
In potted experiment set in greenhouse UWM in Olsztyn two cultivars of perennial ryegrass: ‘Argona’ and ‘Maja’ were examined. Cultivars of grasses at two levels of moisture of soiI: 40%, and 80% field water capacities were compared. In period of growin of measurements of intensity of photosynthesis by measurement of parameters of gas-exchange Li-Cor 6400 and contents of chlorophyll by chlorophyllmeter Japanese firms Minolta were executed. Examined cultivars yielded on similar-identical level. Decisive factor about yielding was moisture soiIs. Greatest decrease of yield under influence lower moistures of soil, in third sucker of cultivars ‘Argona’, i.e. 54,7% was ascertained. Content of chlorophyll in leaves was also dependent on moistures of soil, at greater values at plants tilled in conditioners of water stress were ascertained. Analysed cultivars did not differ in respect or intensities or photosynthesis. The process took place better on soil about greater moistures and was almost half greater in comparison to cultivars tilled on soil about moisture 40% field water capacities.