The aim of the study was to assess the effects of water deficit on yield, leaf area and fluorescence chlorophyll parameters of forage grasses. The pot experiment was conducted in 2013 in IUNG-PIB's greenhouse in Pulawy. Nine cultivars of five species ( Lolium perenne, Lolium multiflorum, Festuca pratensis, Festuca arundinacea and Festulolium braunii) were investigated in well-watered conditions (70% field water capacity) as well as in a short-term drought stress conditions (40% field water capacity). The study showed, that dry matter of yield, chlorophyll fluorescence parameters: quantum of photosynthetic yield efficiency ( Fv/Fm ratio) and performance index ( PI) and leaf area were significantly lower in drought stress than under well-watered conditions in all cultivars in each regrowth. The data demonstrated the highest yield decrease for F. arundunacea cv. Barolex in the first, for L. perenne cv. Melluck and Meltador in the second and for F. braunii cv. Felopa in the third regrowth. The hybrid F. braunii was characterized by the lowest yield reduction and PI parameter in first and second regrowth. Based on the yield average, short drought resistance of different species was in the following order: F. pratensis > F. braunii-L. multiflorum > F. arundinacea > L. perenne. There was a significant relationship between dry matter yield and leaf area, and also between dry matter yield and fluorescence chlorophyll parameters.
