morphophysiological and biochemical changes in tall fescue (festuca arundinacea schreb.) under combined salinity and deficit irrigation stresses

water salinity and drought are the major abiotic stresses limiting turf grass growth. on the other hand, shortage of waterresources and salinity of water and soil in the arid and semi-arid zones such as iran, are the restricting factors in developinglawn turf grasses. an experiment was conducted to evaluate the combined effects of water salinity and deficit irrigation ontall fescue (festuca arundinacea schreb.). this study was conducted under outdoor conditions in a completely randomizeddesign with factorial arrangements. treatments included four water salinity levels (0.5, 3, 6 and 9 ds.m-1) and three deficitirrigation regimes (50%, 75% and 100% fc) with five replicates under outdoor conditions. results indicated a rise in theion leakage, and soluble sugar and proline concentration and a decrease in visual quality, shoot length, leaf area and freshand dry weights of shoot, leaf relative water content (rwc), leaf chlorophyll content and photosynthetic rate and starchcontent with an increase in the levels of both stresses. antioxidant enzymes, superoxide dismutase (sod, ec 1.15.1.1), andcatalase (cat, ec 1.11.1.6) showed higher activity under moderate drought or water salinity conditions; however, thisparameter decreased at higher levels of these salinity stresses. practically, based on the results of the present study, tallfescue could be grown under moderate levels of the combined stresses of water shortage and salinity without considerabledamage to the plant at the physiological and/or biochemical level. this is the first report on applying the combined stressesof water and salinity on an important agricultural crop.