Background: Photosynthesis is among the primary processes affected by drought and its disturbances result with the reduction of growth, reactive oxygen species (ROS) overproduction, and alterations in antioxidant system activity. Our study was performed on two closely related forage grasses: Festuca arundinacea and F. glaucescens. Two genotypes within each species significantly differing with the potential of drought resistance: high drought resistant (HDR) and low drought resistant (LDR), were used. The research involved: (i) the analysis of gene expression at transcript and protein levels for the selected enzymes of Calvin cycle (fructose-1,6-bisphosphate aldolase (pFBA), phosphoglycerate kinase (PGK) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH)) and (ii) the activity of pFBA, as a protein marker of the Calvin cycle, (iii) the analysis of gene expression at protein level for the selected antioxidant enzymes (glutathione reductase (GR), glutathione peroxidase (GPX), L-ascorbate peroxidase (APX), catalase (CAT), and superoxide dismutase (SOD)), (iv) the measurements of physiological parameters describing a plant’s physiological status under control, drought and re-watering conditions (relative water content (RWC), electrolyte leakage (EL), lipid peroxidation, chlorophyll fluorescence, gas exchange, and ROS level).Results: Our analysis clearly showed that physiological reactions to water deficit were similar in both HDR and both LDR genotypes of Festuca arundinacea and F. glaucescens but the species revealed significant differences in the potential to tolerate tissue dehydration, what was correlated with distinct expression of the Calvin cycle enzymes under drought stress.Conclusions: The maintenance of stable efficiency of dark phase of photosynthesis seems to be crucial for drought tolerance and recovery in F. glaucescnes, whereas acquisition of drought tolerance in F. arundinacea and F. glaucescens does not involve marked changes at the protein level in the enzymatic antioxidant system.