Abstract:
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.
Machine summary:
"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.
The plants that can tolerate saline conditions, may alleviate the adverse effect of the stresses (such as water salinity and drought) by synthesizing the metabolism compatible solutes such as proline, which reduces the rate of turgor changes within the cells, and that in turn will prevent protein (enzymes) degradation (Kamal Uddin et al.
Table 3 indicates the effect of the different levels of deficit irrigation and water salinity and their interaction on the visual quality, shoot length, leaf area, fresh and dry weights.
Table 4 indicates the effect of the different levels of deficit irrigation and water salinity and their interaction on the leaf chlorophyll content, photosynthetic rate, soluble sugars content, proline concentration and starch content.
D. (small letters for interactions and capital letters for means) are not significantly different at 5% level of probability using LSD test Drought and water salinity not only reduce growth and development of the plants, they also induce changes in some metabolic pathways (Wu and Garg, 2003).
Practically, based on the results of the present study tall fescue can be grown under moderate combined stresses of drought and water salinity without considerable damage to the plant at a morphophysiological and/or biochemical level."