Drought Stress-Induced Changes in Gas Exchange, Chl a Fluorescence Parameters and Yield in Lolium, Festuca and Festulolium

Changes in yield and physiological processes in drought stress (40 % field water capacity) and well-watered conditions (70 % field water capacity) in forage grasses were investigated. Nine varieties from five species (Lolium perenne, Lolium multiflorum, Festuca pratensis, Festuca arundinacea and Festulolium braunii) were examined in a pot experiment in a greenhouse in 2013–2014 in Poland. The aim of the study was to assess the effects of water deficit on different forage grasses. All measured physiological parameters were affected by drought stress in the different cuts. Intensity of photosynthesis, transpiration rate and dry matter yield were significantly lower in drought stress than under well-watered conditions in all varieties. The differences in chlorophyll fluorescence (the Fv/Fm ratio, an estimation of the PSII phytochemical efficiency) were less pronounced, although most of varieties showed a minor but significant decrease of the Fv/Fm ratio under drought stress.