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In most parts of Iran, the presence of water and soil salinity in urban area results in problems for grass growth. One way to solve this problem is the use of plant growth retardant, such as trinexapac-ethyl (TE), which is common and routine in turf management. This study was performed to investigate the response of Agrostis stolonifera L., Agropyron desertorum L. and Festuca ovina L., grown in sandy loam soil, to TE and irrigation water salinity. Resu-lts showed that spraying turf grass with TE increased most of the vegetative growth characteristics and content of chlo-rophylls, carotenoids and proline in clipping leaves, whereas increasing the NaCl concentration in irrigation water resu-lted in steady reduction in the values of these parameters, except carotenoids and proline content, compared with the co-ntrol group. Both TE and salinity treatments decreased the plant heights, as well as the fresh and dry weight of clip-pings. In the species which were studied, Agrostis stolonifera turned out to be the most tolerant turfgrass. Results also indicated that the application of TE enhances salinity resistance by improving the percentage of green leaf, chlorophyll concentration and proline content and reduce clipping in the species studied

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A laboratory experiment was carried out to investigate the effect of salinity on some morphological and phys-iological parameters in four Canola (Brassica napus L.) cultivars (Talaye, Sarigol, Zarfam and Opera) under salinity stress. Plants were grown in hydroponic solution (Hoagland 1/4 strength) under greenhouse conditions and on five-leaf stage, treated with different concentrations of NaCl: 0 (control), 50, 75 and 100 mM. After 14 days of treatment, plants were harvested and the length of shoots and roots, photosynthesis, chlorophylls and carotenoids contents of leaves were measured on four studied cultivars. In general the results showed that increasing salinity reduced leaf relative water co-ntent, shoot and root lengths and leaf area. Photosynthetic rate was declined in Talaye and Sarigol, but it was elevated in Opera and Zarfam. It should be noted that the changes induced by salinity on photosynthetic pigments was not regu-lar. The results of this study showed that among the investigated cultivars, in vegetative phase, Opera and Zarfam had higher capacity and function to salt stress tolerate than other cultivars. It also seems that Sarigol may be more vuln-erable than other cultivars under salinity stress.

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In recent years, the involvement of nitric oxide (NO) in numerous physiological processes, particularly the mitigation of stress-induced negative effects on plants, has been clarified. Under salinity conditions, plants are subjected to a secondary oxidative stress.  The present work was designed to examine the exogenous application of nitric oxide (NO), in the form of its donor sodium nitroprusside (SNP), in mitigating the deleterious effects of salinity on Zygoph-yllum fabago L. plants. SNP (200 µM) was applied to plants growing medium under saline (200 and 400 mM NaCl) and non-saline conditions. Growth, oxidative stress markers [cell membrane stability index (MSI) and H₂O₂ conc-entration], antioxidant enzymes activities [peroxidase (POX, EC 1.11.1.7) and catalase (CAT, EC 1.11.1.6)], as well as the contents of some antioxidant compounds (flavonoids and carotenoids) were determined. Salinity lowered the shoot and root dry weights, while it enhanced peroxidase and catalase activities. High salinity increased H₂O₂; however, it de-creased the carotenoids content of leaves. Exogenous NO enhanced the growth, MSI, flavonoids and carotenoids co-ntents of salinized plants. In salinity plus SNP treated plants, H₂O₂ concentration and the activities of the examined en-zymes were reduced. Data suggest that a cooperative process is performed by the antioxidant systems in Syrian bean ca-per in order to cope with salinity. Also, the application of exogenous NO was found to be useful in the mitigation of salinity-induced oxidative stress in plants.