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 water resources and salinity of water and soil in the arid and semi-arid zones such as Iran, are the restricting factors in developing lawn turf grasses. An experiment was conducted to evaluate the combined effects of water salinity and deficit irrigation on tall fescue (Festuca arundinacea Schreb.). This study was conducted under outdoor conditions in a completely randomized design with factorial arrangements. Treatments included four water salinity levels (0.5, 3, 6 and 9 dS.m-1) and three deficit irrigation regimes (50%, 75% and 100% FC) with five replicates under outdoor conditions. Results indicated a rise in the ion leakage, and soluble sugar and proline concentration and a decrease in visual quality, shoot length, leaf area and fresh and dry weights of shoot, leaf relative water content (RWC), leaf chlorophyll content and photosynthetic rate and starch content with an increase in the levels of both stresses. Antioxidant enzymes, superoxide dismutase (SOD, EC 1.15.1.1), and catalase (CAT, EC 1.11.1.6) showed higher activity under moderate drought or water salinity conditions; however, this parameter decreased at higher levels of these salinity stresses. Practically, based on the results of the present study, tall fescue could be grown under moderate levels of the combined stresses of water shortage and salinity without considerable damage to the plant at the physiological and/or biochemical level. This is the first report on applying the combined stresses of water and salinity on an important agricultural crop.