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In order to study the interaction effects of salinity and ascorbic acid on the photosynthetic pigments, soluble sugar, proline, and protein in Satureja khuzestanica plant, factorial experiment was conducted in a completely randomized design (salinity in 4 levels 0, 40, 80 and 120g in 100kg soil and ascorbic acid in 2 levels 0 and 2 mM ) with 6 replicates. The results showed that salt stress reduced photosynthetic pigments amount by increasing the soil salinity from 0 to 40g NaCl in 100kg soil and then increased by 80g NaCl in 100kg soil and again decreased by concentration of 120g NaCl in 100kg soil. The amount of solouble sugar, proline and protein by the soil salinity increased from 0 to 40g in 100kg soil and then decreased in concentration of 80g NaCl in 100kg soil, in 120g NaCl in 100 kg soil increased amount of characters. In present of ascorbic acid photosynthetic pigments amount of pigments increased by increase the soil salinity from 0 to 40g NaCl in 100kg soil and then decreased by 80g NaCl in 100kg soil and again increased by concentration of 120g NaCl in 100kg soil. But, amount of solouble sugar, proline and protein by the soil salinity decreased from 0 to 40g in 100kg soil and then increased in concentration of 80g NaCl in 100kg soil. Finally, in 120g NaCl in 100kg soil decreased amount of characters.

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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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In order to study the diverse effects of seed priming with 24-epibrassinolide (EBL) (0, 0.1, 1 mg/l) to increase tolerance of tomato plants (Lycopersicon esculentum Mill.) to salinity (0, 70 and 140 mM NaCl), the experiments were conducted as factorial based on completely randomized design at greenhouse condition. Results showed that salt stress significantly decreased the growth of tomato plants. However, priming with EBL (1 mg/l) significantly decreased the negative effects of NaCl (particularly at 140 mM). At this case, EBL increased the fresh and dry weights (<2 folds), total chlorophyll (+72%), carotenoids (+ 2 folds), free proline (+3 folds), electrolyte leakage (-18.6%), Na⁺/K⁺ in the roots (-57.5%) and shoots (-62%) compared to salinity control. Generally, it could be concluded that priming with epibrassinolide resulted in enhanced salt tolerance in tomato plants via increment in free proline, photosynthetic pigments and decrease in electrolyte leakage and Na⁺/K⁺ ratio in the tissues.
 

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Plant growth is greatly influenced by environmental stresses including water deficit, salinity and extreme temperatures. Therefore, the identification of genes, especially regulatory ones whose expression enables plants to adapt to or to tolerate these abiotic stresses, is very essential. MYB proteins, a superfamily of transcription factors, play regulatory roles in developmental processes and in defense responses in plants. Members are characterized by a structurally conserved DNA-binding domain, i.e., the MYB domain. Thus, a factorial experiment in a randomized complete block design with three replications was carried out to investigate the effect of different levels of drought stress on the relative expression of TaMYB73 transcription factor gene using Real Time PCR method at Biotechnology Research Institute of Zabol University. The experimental treatments included durum wheat genotypes (Shabrang, Behrang, Karkheh, Aria and Dena) and drought levels (5, 10, 15, 20 and 25% of field capacity). Seedlings of genotypes
were cultured in pots and drought stress was exerted after 45 days (four to five leaves). Data analysis was performed using Ratio =2 ^-ΔΔCT and SAS software version 9.1. The results of the 2-way ANOVA for the effect of genotype, drought stress and cross-effects of drought stress on the relative expression of TaMYB73 gene and the amount of osmotic regulators (Proline and Carbohydrate) at different stress levels (20, 15, and 5% of field capacity) were significant in comparison with the normal condition (25% of field capacity) at 1% probability level. With the increase of drought stress level from 5 to 20% of crop capacity, relative to the normal level (25% crop capacity), the relative expression of TaMYB73 gene and osmotic regulators of proline and carbohydrates increased in Beharang, Karkheh and Dena genotypes. Therefore, Karkheh and Dena genotypes showed greater resistance to drought stress among the 5 genotypes studied.
 

 

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One of the major abiotic stresses that negatively affects plants is the presence of heavy metals. Soil pollution with heavy metals, resulting from the industrial development and use of fertilizers containing heavy metals, has become a major environmental concern in human societies. Mercury is a toxic heavy metal that causes pollution in agricultural lands. Accumulation of Hg by plants may disrupt many cellular functions and block growth and development. Under such conditions, the enzymatic and non-enzymatic defense systems of plants are activated. Several defense systems are cooperating together in plants to cope with stressful situations. In this study, the effect of different concentrations of mercury on the photosynthetic pigments content and non-enzymatic defence systems in Nicotiana tabacum was studied. After planting the plants under the same conditions in the hydroponic medium and feeding the plants with Hoagland solution, treatments with different concentrations of mercury nitrate (0.5, 1 and 3 mM and a control group) were applied to the seedlings in three replications. Ten days after the application of the treatments, the plants were harvested and examined. The results showed that tobacco plants which had been exposed to heavy metal used the accumulation of osmolytes such as proline and soluble sugars in order to balance their osmotic pressure. The decrease in the amounts of photosynthetic pigments and increase in the levels of malondialdehyde in the leaves indicated the elevation of oxidative damage. Increased activity of non-enzymatic antioxidants in tobacco leaves, including anthocyanins, phenol, flavonols and flavonoids, can be interpreted as the mechanisms of resistance to heavy metal stress induced by mercury.