مقالات رزومه دکتر پویان مهربان جوبنی

This study was investigated the patterns of water quality changes and the identification of invasive aquatic plant species in drinking water dams located in Mazandaran province, including Alborz, Shahid Rajaei and Meijran Dams. The best conditions of dissolved oxygen in Alborz, Shahid Rajaei and Meijran dams were around 10, 10 and 16 mg/L in April, respectively. Due to the thermal stratification created in August and September, the content of dissolved oxygen in all dams at a depth of 7 to 10 meters reached zero. Based on Carlson's index, these dams were eutrophic during these months. The highest amount of phosphate measured in July, August and September was observed in Meijran Dam. However, biological pollution of Alborz and Shahid Rajaei dams were higher than Meijran dam, the biological and chemical oxygen demand of Alborz and Shahid Rajaei dams were about 2 and 2.5 times higher than Meijran dam, respectively. Also, the amount of faecal coliform in Alborz dams was about 2 time compared Meijran dam. Despite the decrease in the amount of total coliform in three dams in September, the amount of faecal coliform in Alborz dam was about 3 times other dams. Two plants, hydrilla and Potamogeton, were observed as the invasive plants in Meijran dam, which seems that cormorant bird are the cause of invasive plants entering the dam.

Sesame is one of the oldest products known to man to date. Sesame was a valuable crop in the ancient world due to its drought resistance, ease of oil extraction from seeds and oil stability. Iran is one of the arid and semi-arid regions of the world in terms of climate. In these areas, low and scattered rainfall and high evaporation usually cause the accumulation of salts in the surface layer of the soil. Therefore, the salinity of soil and irrigation water causes significant morphological, physiological and chemical changes. Excess salt, that is, more than plants need limits crop growth and production and can lead to plant death.

In this experiment, 20 sesame genotypes were grown in greenhouses. The experiment was performed as a factorial in a completely randomized design with three replications. 75 mM sodium chloride was dissolved per liter of water and the pots were irrigated with saltwater. Percent morphological traits loss index (PML) was calculated.

According to the results of analysis of variance and comparison of the mean interaction of cultivar × stress in all studied traits were significant. American and Yellow- White cultivars with 17927 and 14.07 g, respectively, the highest and 714 and Dezful with 2.43 and 2.07 g, respectively, the lowest yield under normal conditions, and Oltan and American cultivars, respectively, with an average of 963 8.8 and 7.34 g had the highest and Darab 1 and Dezful had the lowest yield under stress conditions with 0.92 and 0.71 g, respectively. In this study, clustering method was used to group and separate useful (high yield) and susceptible (low yield) genotypes based on different traits. The results showed that the studied genotypes were grouped based on morphological traits and yield reduction percentage index using standard data. The studied genotypes were divided into 3 groups. In the first group, Oltan, American, Chinese, Dashtestan 2, 369 and 418 genotypes with the highest yield among the genotypes were studied. The second group included Darab 1, 730 and Dezful genotypes and the third group included other genotypes. In the first group, it is desirable to distinguish high-yield genotypes with desirable traits and the lowest percentage of yield reduction under salinity stress conditions from other genotypes.

The results of this experiment showed that there is a favorable variation among the study population, especially a significant difference was observed between the performance of genotypes in both normal environmental conditions and salinity stress. Correlation analysis of traits showed that under normal conditions, number of seeds per plant, number of capsules per plant and 100-seed weight, and under salinity stress, number of seeds per plant, number of capsules per plant and single plant weight had the highest correlation with yield. In this experiment, the best salinity tolerant lines were Oltan, American, Chinese, Dashtestan 2, 369 and 418 genotypes. It is noteworthy that these genotypes had a more stable performance than others in both conditions, so they have stress tolerance genes and can be considered in future studies. Also Darab 1, 730 and Dezful genotypes were the most sensitive genotypes to salinity stress in this experiment.

Introduction : 

Sunflower meal is considered as an attractive alternative to soybean meal due to its adaptation to dry and temperate climates as well as its lower anti-nutrient content than other oilseeds. Sunflower meal has a limiter that restricts its use in broiler diets. The fiber in sunflower meal has limited its use in the diet of broilers due to reduced metabolic energy as well as production. Fermentation, which uses beneficial microorganisms, can reduce the chemical composition of the feed and increase the yield of broilers by producing enzymes and using fiber as a feed source. In this study, in order to investigate the effect of fermentation on sunflower meal, growth yield, microbial population composition, blood parameters in broiler chickens were performed.

The research was conducted at the research farm of Sari University of Agricultural Sciences and Natural Resources in 2020. In this study, 200 commercial male Ross 308 broilers were used in a completely randomized design with five treatments, five replications, and eight chickens per replication. The treatments included: 1) Control diet, 2) Diet containing sunflower meal (negative control), 3) Diet containing sunflower meal fermented with Aspergillus Oryzae, 4) Diet containing sunflower meal fermented with Penicillium Funiculosum, and 5) Diet containing sunflower meal fermented with Aspergillus Oryzae and Penicillium Funiculosum. Sunflower meal was obtained from Behpak Behshahr (Mazandaran) company, ground in the animal nutrition laboratory of Sari University of Agricultural Sciences and Natural Resources, and sieved to a size of 2 mm. Aspergillus Oryzae (PTCC5010) and Penicillium Funiculosum (PTCC5301) were purchased as lyophilized vials from the Fungus and Bacteria Collection Center of the Iranian Research Organization for Science and Technology (IROST). During the fermentation process, 1.1 liters of the mixture of distilled water and primer culture (containing at least 105 colony forming units per ml) was added to each kilogram of sunflower meal, and the resulting mixture was thoroughly mixed by hand for 15 minutes. The mixture was fermented in special tanks (with a one-way valve to remove the produced gases and prevent air from entering) for 7 days at 30 °C, and finally, the fermented sunflower meal was dried for three days at room temperature. All chickens were kept under the same breeding conditions during the 39-day period and had free access to feed. Experimental diets were adjusted to three periods: initial (1-10 days), growth (11-24), and final (25-39) using Table 1 of the Ross 308 Catalog of Nutritional Requirements for Broilers. The pH of fermented sunflower meal was determined using the Chiang et al. method. Sunflower meal was sampled before and after fermentation to measure dry matter, ash, crude protein by the Kjeldahl method, crude fat by Soxhlet device, and insoluble fibers in acidic detergent and neutral detergent using a fibrotec device. Total amino acid was measured by the ninhydrin method. Soluble sugar was measured by the intron method. Total phenol content was measured using the Folin-Siocalcu reagent and spectrophotometry. Soluble proteins were measured by the Bradford method.

During the fermentation of sunflower meal, pH, crude fat, soluble protein and soluble sugar decreased. The amount of crude protein, total amino acid, insoluble fiber in acidic detergent, and insoluble fiber in neutral detergent increased. In the whole breeding period, body weight gain was improved in treatments fed with fermented feed. In the treatment of Aspergillus Oryza + Penicillium funiculosum, feed consumption decreased compared to control, negative control and Penicillium funiculosum treatments. The feed conversion ratio increased in the negative control treatment at the age of 1-39 days compared to other treatments. In the ileum, coliform bacteria decreased in negative control treatments, Aspergillus Oryzae, Aspergillus Oryzae + Penicillium funiculosum compared to the control treatment, but Penicillium funiculosum treatment increased compared to other treatments. At 39 days of age, the use of fermented and raw feed increased the level of HDL-c in the negative control and Aspergillus Oryzae + Penicillium funiculosum treatments. The amount of LDL-c increased in the treatments of Aspergillus Oryzae and Penicillium funiculosum

Based on the results, the use of fermented feed in the feeding of broiler chickens during the entire breeding period has improved weight gain and feed conversion ratio.

Salinity stress is one of the factors that reduced the growth and yield of crops. The response of C3 and C4 plants to salinity stress and possible mitigation of the effects of this stress with the application of silicon and nanosilicon may be different according to the photosynthetic pathway of these plants. Therefore, this study was conducted to compare the response of wheat as a C3 plant and sorghum as a C4 plant to the effect of silicon and nanosilicon application on salinity stress mitigation.

Two experiments were conducted in a completely randomized design with factorial arrangement in pots filled with soil at Sari University of Agriculture and Natural Resources in 1398. The salinity factor was at two levels included 0 and 100 mM NaCl and the silicon factor was at three levels included 0 and 2 mM potassium silicate and 2 mM nanosilicon (SiO2)). Both forms of silicon were applied as foliar application. Plant photosynthesis-related traits were measured after 13 days of treatments the next day the plants were harvested for growth measurement and other biochemical assays.

The results of this study showed that salinity caused a significant reduction in fresh and dry weight of plants in both wheat and sorghum plants. Application of silicon in wheat and application of nanosilicon in sorghum caused a significant increase in fresh and dry weight of plants under salinity. Application of silicon and nanosilicon had no significant effect on stomatal conductance and transpiration of wheat and sorghum plants under salinity. In wheat plants, silicon foliar application significantly increased photosynthesis rate under salinity, but nanosilicon had no significant effect. On the contrary in sorghum, the use of silicon had no significant effect on the photosynthesis rate under salinity, but nanosilicon increased the photosynthesis rate of sorghum plants. In sorghum plant, under salinity conditions, the use of silicon and nanosilicon reduced the amount of hydrogen peroxide contents by 21 and 30%, respectively, and the amount of lipid peroxidation by about 13 and 23%, respectively. However, the use of silicon and nanosilicon did not indicated a significant effect on the content of hydrogen peroxide the amount of lipid peroxidation wheat plants grown under saline condition. The application of silicon in wheat plants increased 58% of the total fresh weight and 68% of the total dry weight of plants under salinity, although the application of nanosilicon had no significant effect. The use of silicon and nanosilicon increased the fresh and dry weight of sorghum plants under salinity, but the additive effect was greater by application nanosilicon, so that the total dry weight of sorghum plants under salinity in nanosilicon treatment were 75% higher than plants without this treatment.

This study showed that the use of silicon in wheat plants under salinity improved photosynthesis and thus reduced the effects of salinity on growth to some extent, but nanosilicon in this plant did not have such an effect. Conversely, in sorghum plants under salinity, the use of nanosilicon by reducing the amount of hydrogen peroxide and lipid peroxidation, reduced the oxidative stress caused by salinity and increased the photosynthesis rate of the plant, which led to more growth of plants under salinity stress. Such cases were not observed with the use of silicon.

One of the ways to overcome the limitation of fresh water and lack of sufficient water reserves for agriculture is to use unconventional waters such as seawater. Salinity stress is the most important abiotic stress in seawater application. Identification and planting of salinity tolerant genotypes of a plant species is one of the effective and valuable strategies in reducing the effects of salinity stress. Germination, growth and seedling establishment are among the salinity-sensitive stages in most plants. Therefore, for improvement of abiotic stress tolerance in plants, it is necessary to study the traits and indicators related to tolerance in the germination stage.

A factorial experiment was conducted based on a completely randomized design with three replications at the laboratory of Plant Breeding Department of Sari University of Agricultural Sciences and Natural Resources in 2020. The first factor included the cultivars and the second included 5 salinity levels (control (no seawater), 3, 6, 9 and 11 dS (deciSiemens per meter) obtained from the incorporation of Caspian Sea and urban water. The number of germinated seeds was counted during eight days of salinity stress. Then, germination percentage, time required for 50% germination, seedling vigor index and germination rate were calculated. On the eighth day, radicle and plumule dry and fresg weights, radicle and plumule length and seedling dry weight were measured.

The results of analysis of variance showed the significance of the effect of different salinity levels, genotype and the interaction of salinity and genotype for all calculated indices at p<0.01. Mean comparison of the interaction of different levels of salinity and cultivars and landraces showed that all the studied traits except for the time to reach fifty percent germination decreased with increasing salinity. Among the studied cultivars, Oltan cultivar had the highest value of germination percentage (100%), germination rate (24.17 seeds per day), seedling vigor index (5.03), plumule length (55.67 mm), radicle length (70 mm), plumule fresh weight (62 mg), radicle fresh weight (45 mg), plumule dry weight (4.77 mg), seedling dry weight (6/23 Mg) and the lowest amount of the time required for 50% germination (24.17 hours) in control treatment. In contrast, Pakistani cultivar had the lowest germination rate (3.06 seeds per day), seedling vigor index (1), plumule length (8.33 mm), radicle length (3 mm), plumule fresh weight (10 mg), radicle fresh weight (2 mg), plumule dry weight (0.57 mg), seedling dry weight (0.84 mg) and the highest time required for 50% germination (24.17 hours) in 11 dS / m salinity level. Using the results of this experiment, among the studied cultivars, Oltan cultivar was selected as the most tolerant and Pakistani cultivar as the most sensitive cultivars to salinity stress at the germination stage.

The studied cultivars and landraces showed different reactions in terms of germination indices when treated with salinity from seawater. The high significant difference in this experiment indicated the high genetic diversity among the studied genotypes. It is possible to choose from these genotypes for salinity tolerance breeding programs in sesame plant.

Sesame (Sesamum indicum L.) is a nutritionally and medicinally important oilseed crop that environmental stresses limit its yield potential. Ethylene-responsive factor (ERF) is one of the largest transcription factor families that play key roles in regulating plant response to abiotic stress. In the current study, a total of 113 ERF genes were identified from the sesame genome and they were divided into two subfamilies including, 46 dehydration-responsive element-binding (DREB) members, and 67 ERF members. Phylogenetic relationships, physicochemical properties of proteins, structural properties of genes, and conserved amino acid motifs in the sesame ERF family were analyzed. Then, the expression profile of sesame ERF genes in various tissues as well as under environmental stresses was investigated. Overall, several genes of the ERF Family were expressed noticeably in different sesame tissues, especially in roots, capsules, and flowers. Expression profiles also showed that RAP2.2L, PTI6, ERF017L, and ERF096 genes were strongly induced by drought, osmotic, salinity, and waterlogging stresses, respectively. Moreover, the qPCR results showed that the relative expression of the ERF061L gene was higher in the sesame tolerant genotype compared to the susceptible one under drought conditions. This study provides important data for understanding the evolution and functions of the ERF family in sesame that can be used in future breeding programs for abiotic stresses tolerance.

Sesame as one of the most important oilseed crops has high industrial, food, and medicinal potentials. Drought stress challenges sesame production, especially at the germination and seedling stages. To screen sesame genotypes for drought tolerance at the germination stage, a factorial experiment was performed in a completely randomized design with 3 replications. The studied factors included 4 drought levels induced by polyethylene glycol (concentrations of 0%, 20%, 25%, and 30%) and 15 sesame genotypes. Based on the results of ANOVA, the effect of genotype, drought, and their interaction on all studied traits including germination rate, germination speed, vigor index 1 and 2, radicle length, plumule length, and seedling fresh and dry weight was significant (P<0.01). Significant reduction (P<0.05) was observed in all levels of stress compared to the control in the studied traits. Germination rate, radicle length, and plumule length (with 10%, 17%, and 18% reduction, respectively) showed less sensitivity to drought stress at weak level (20% concentration), while the most negative effect was obtained for vigor index 2, seedling dry weight and seedling fresh weight (with 52.5%, 47.3%, and 34.4% reduction, respectively). On the other hand, the highest decrease was observed in plumule length, vigor index 1 and 2 (98%, 97%, and 96%, respectively), under severe drought (30% concentration). The calculated drought tolerance indices of each trait were used for principal component analysis and biplot visualization. Thus, genotypes were divided into 5 categories based on tolerance. Dashtestan 2 and Darab 1 genotypes were selected as the most tolerant and Qaem, Yekta, Sudan, and Kerman genotypes were selected as the most sensitive genotypes. The findings of this study can be used in future studies and breeding programs of sesame for drought tolerance.

Sesame seeds are a good source for food and health due to their protein and unsaturated fatty acids and secondary metabolites such as lignans. Soil and water salinity is one of the most important factors limiting the growth of this crop. By examining the physiological reactions related to salinity tolerance among different landraces and cultivars, tolerant and sensitive cultivars can be selected and used in breeding programs and cultivation development of this important oilseed. For this purpose, physiological reactions in eight different sesame genotypes in a factorial experiment based on a completely randomized design with the main salinity factor due to mixing Caspian Sea water with normal water at 3 levels(control, 6 & 9 dSm-1) and sub-factor 8 Sesame genotype includes Babol, Dashtestan 2, Oltan, Pakistani, tn-78-389 and tn-78-393, Halil, Naz single-branched genotypes in three replications in pots in the greenhouse of the Plant Breeding Department of Sari University of Agricultural Sciences and Natural Resources in the year 2020 were examined. The results of this experiment showed that at salinity levels of 6 and 9 dS, among the eight different genotypes of sesame studied, Oltan cultivar with the highest amount of total dry weight (8.42 & 5.27 gr), proline (10.35&15 μmol/g fresh leaf weight), membrane stability index ( 82.65&74.14%), relative water content(81.33 & 69.33%), leaf chlorophyll and carotenoid content(based on mg/g fresh weight), chlorophyll a(0.74&0.7),total chlorophyll(1.12&0.95)and carotenoids(0.41&0.46)and antioxidant enzymes activities (based on enzyme unit per gram fresh weight), superoxide dismutase(18.22&29.05), ascorbate peroxidase(14.9&19.21),catalase(1.51), guaiacol peroxidase(4.8&5.43),potassium(6.6%),sodium to potassium ratio index (0.06&0.12) and the lowest amount of sodium(0.41&0.7)was more tolerant of stress than other cultivars. In contrast, Pakistani cultivar with the lowest amount of total dry weight (5.12 & 2.14 gr), proline(5.86&6.7 μmol/g fresh leaf weight), membrane stability index(66.31 & 57.86%), relative water content (58&48.33%), leaf chlorophyll and carotenoid content (based on mg / g fresh weight), chlorophyll a(0.46&0.37), total chlorophyll(0.69&0.5)and carotenoids(0.25&0.27)and Antioxidant enzymes activities (based on unit of enzyme per gram of fresh weight), superoxide dismutase (11.61&10.31), ascorbate-peroxidase (8.61&8.78),catalase(0.84),guaiacol peroxidase(1.77&2.16), potassium(3.68%), sodium to potassium ratio index(0.59&1.12)and the highest amount of sodium(2.15&2.57)was the most sensitive cultivar in stress tolerance compared to other cultivars. Based on the evaluated traits and the response of the studied cultivars to salinity stress, oltan was identified as a tolerant cultivar and Pakistani as a salinity sensitive cultivar compared to the other cultivars. Therefore, these cultivars can be suggested for use in future breeding programs to introduce new cultivars.

Salinity stress is one of the factors that threatens the growth and yield of corn. The effects of silicon or nanosilicon on salinity alleviation have been reported in some plants. The effects of foliar application of silicon (inorganic and nanopatricle) on mitigation of the effects of salinity stress on some photosynthetic and biochemical parameters were studied in corn. Experiments were conducted in a completely randomized design with factorial arrangement in a pot culture. The first factor was salinity at two levels including 0 and 100 mM NaCl and the second factor was silicon at three levels including control (without silicon) and 2 mM potassium silicate and 2 mM nanosilicon (SiO2). Under salinity stress, the fresh and dry weights of shoots and roots, the chlorophylls and carotenoids contents, and the amount of soluble protein decreased significantly compared to the control. In contrast, the amount of hydrogen peroxide and malondialdehyde increased in these plants. Also, the photosyntheic rate and water use efficiency of plants decreased under salinity. The application of silicon and nanosilicon improved the growth of plants under salinity and increased the photosynthetic rate and the amount of photosynthetic pigments. In addition, severe reduction in transpiration under silicon application compared to nanosilicon resulted in the increased water use efficiency in this treatment. Silicon application also increased the activity of soluble peroxidase enzyme in plants under salinity, a result which was not observed with nanosilicon application. This resulted in a further decrease in hydrogen peroxide and lipid peroxidation of plants under salinity treated with silicon compared to nanosilicon, which showed a further decrease in oxidative stress in this treatment. These findings indicated that stress reduction and growth improvement of the plants under salinity with silicon application were more than the treatment with nanosilicon.

Induction of soil acidity in the condition of waterlogging in rice fields increases the solubility and uptake of silicon and iron. In this research, the effects of 1.5 mM silicon (in the form of sodium silicate) and extra iron (150 mgL-1 as Fe-EDTA) on physiological parameters of the rice plants were evaluated. After 7 days, in plants treated with 1.5 mM silicon, the minimum and maximum of chlorophyll fluorescence in dark conditions, variable fluorescence and non-photochemical quenching of PSII increased by 27, 20, 19 and 8 percent respectively, but application of silicon in seedling treated with 150 mgL-1 Fe reduced the maximum fluorescence by 23% in light conditions and increased about 55% non-photochemical quenching of PSII. In plants treated with silicon, the amount of root and shoot Si, root and shoot iron and calcium of shoot were increased by 14, 20, 88, 33 and 8 percent, respectively, and the calcium content of root decreased by 11 percent. In the cross section of the root tip of plants treated with 150 mg L-1 iron, the ratio of cortex area to protoxylem area increased significantly compared to the control plants. This study showed that Si induced growth of plants by increasing of photosynthesis capacity and improving relative water content, however, Fe excess decreased growth due to the reduction of quantum yield, decline in water equilibrium and increase of cell wall components in younger parts of roots. Silicon application did not decrease Fe accumulation in plants and could not mitigate effects of iron toxicity on plant growth.

In the present study, the effects of silicon nutrition under salinity stress have been investigated on Arabidopsis thaliana plants grown on hydroponic culture. The experiments were conducted in a completely randomized design in factorial form. The first factor was salinity including 0, 50, 100 and 150 mM NaCl and the second factor was silicon including 0 and 1.5 mM sodium silicate. The results indicated that salinity increased concentration of Na+ and decreased relative water content and concentration of Ca2+, K+ and Mg2+ about 27, 49, 66 and 19 percent respectively. Consequently, plants were faced with oxidative stress that caused enhancement of antioxidant enzyme activities as well as phenols. In addition, salinity stress increased soluble sugars and decreased starch content that probably indicated plant acclimation for insufficient osmotic adjustment. Silicon nutrition alleviated the oxidative stress caused by salinity that may associated to the increasing K+ and Mg2+ content and raising antioxidant enzymes activity. Beside, increase of reducing sugars, decrease of starch and enhancement of relative water content following silicon application indicated improvement of plant water status. As a result, silicon fed plants indicated greater growth compared to non silicon fed ones under salinity. The results indicated that silicon could mitigate salinity stress in Arabidopsis thaliana plants through minimizing oxidative stress and improvement of water status.

The present study sought to compare the effect of seed priming by hydropriming, ascorbate and calcium chloride (CaCl2) versus different concentrations of silver nanoparticles on two Iranian rice cultivars (Hashemi and Shiroodi) under drought stress. The experimental design, which was factorial, was completely randomized. The first factor was control (without priming), hydro-priming, 20 mg.L-1 calcium chloride, 20 mg.L-1 ascorbates and 20, 40 and 80 mg.L-1 of silver nanoparticles. The second factor was the drought stress, including control, -1.48 and -4.91 bars created by polyethylene glycol 6000 solutions. In plants without drought stress, the time required to reach 50% germination (T50) reduced to 34 and 54 percent under ascorbate and CaCl2 priming in the Hashemi and Shiroodi cultivars, respectively. In the drought stress condition, ascorbate and hydropriming pretreatments decreased T50 and the time required to reach 90% germination (T90) more than silver nanoparticles, especially in the Shiroodi cultivar. On the other hand, in comparison with other pretreatments, CaCl2 had an important role in increasing the growth factors in all of the drought stress treatments. Although 40 mg.L-1 silver nanoparticles increased the growth factors to some extent, it seems that higher levels of silver nanoparticles cause stress in seeds and therefore decrease the seed germination and growth of seedlings. By decreasing reactive oxygen species, Ascorbate improves the germination and by increasing plasma membrane efficiency, CaCl2 enhances the seedling growth under drought stress.

Salinity is one of the most important stress resulting depletion of vegetation in large areas of the world including some regions of Iran. Reduction of plant growth due to salinity occurs with a range of mechanisms, including low external water potential, ion toxicity and interfere with the uptake. Silicon (Si) is the second most abundant element in soil and could efficiently mitigate the effects of various biotic and abiotic stresses, such as drought, heavy metal toxicity and salinity on plants. Medicago scutellata is an important leguminous forage crop throughout the world that could increase soil nitrogen content via reduction of atmospheric nitrogen. To our knowledge, no study have examined the interaction of salinity and Si nutrition in Medicago scutellata or how the beneficial effects of Si in salt-stressed M. scutellata plants (if any) are exerted. Accordingly, the aim of the present study was to evaluate the effect of silicon nutrition on salt tolerance of Medicago scutellata.
Seeds of alfalfa (Medicago scutellata L.) were sterilized with a 2.5% sodium hypochlorite solution and were incubated in a moistened paper towel. Then, they germinated in the dark at 255  C for 48 h. Healthy seedlings of uniform sizes were selected for hydroponic culture (Hoagland solution) in a 10×15×15 cm plastic pots. A factorial experiment carried out based on a completely randomized design with two factors. The first factor was salinity, including 0 and 100 mM NaCl and the second was silicon nutrition, including 0, 0.75 and 1.5 m.M sodium silicate. The pH of the nutrient solution was adjusted daily at 6.4  0.2 and nutrient solution was refreshed weekly. During the experiment, maximum and minimum air temperatures were 30ºC and 21ºC respectively, and the mean relative humidity was 67%. Four weeks after exerting the treatments, plants were harvested and used for the assessment of growth parameters and chemical analyses.
Salinity led to a significant reduction in both the fresh and dry weights of the plants. On the contrary, the dry weight of the plants improved significantly under saline conditions when Si was added to the medium, especially 1.5 mM Si. Salt treatment increased the concentration Na and decreased the concentration K significantly in both shoots and roots; however, Na concentration, reduced and K concentration increased due to Si application in salt treated plants. Similarly, Fe content decreased in shoot of plants due to salinity, whereas Si nutrition increased Fe content in plants suffered from salinity. The activity of catalase declined and the amount of hydrogen peroxide increased in plants under salinity. Conversely, Si treatments, especially, at 1.5 mM could recover the activity of this enzyme and reduced hydrogen peroxide content. Salinity imposed significant reduction in the contents of chlorophylls, total carotenoids and xanthophylls and soluble proteins. The amount of hydrogen peroxide, lipid peroxidation as well as electrolyte leakage via plant leaves increased due to salt stress. In contrast, the contents of chlorophylls, carotenoids and xanthophylls, soluble proteins increased following Si application. Also, the amount of hydrogen peroxide and rate of lipid peroxidation and electrolyte leakage decreased in salt-treated plants by Si application. Silicon nutrition can recover the chlorophyll content and the amount of soluble proteins on Medicago scutellata plants under salinity, which suggests that it plays a role in the suppression of oxidative stress. Si application also improved the chlorophyll content of tomato and barley under salt stress (Al-aghabary et al., 2004). The data reported in the present study show new aspect of the beneficial effect of Si on plants grown under saline condition. The application of Si prevented Na accumulation and enhanced K content in Medicago scutellata plants. Reduced Na accumulation improves the plant ROS scavenging capacity through increased antioxidant enzyme activity (Al-aghabary et al., 2004 Hashemi et al., 2010), accompanied by reducing lipid peroxidation. Consequently, photosynthetic pigments increased and membranes functionality improved by Si in plants under salinity (Liang et al., 2005).
The results indicated that 1.5 mM silicon application alleviated harmful effects salinity, probably through declined Na enhanced K content that increased antioxidant enzyme activity and reduced reducing oxidative stress. Consequently, photosynthetic pigments increased and membranes functionality improved with plants under salinity. In this regards, Si application led to an increased salt tolerance of Medicago scutellata. Further, field experiments are necessary for confirmation of the results and expedience of economic cost.

This study aimed to evaluate the ameliorating effects of silicon nutrition on Festuca arundinacea under salinity stress. A completely randomized design was used to study the effects of different levels of salinity including 0 and 100 mM NaCl and silicon nutrition including 0, 0.75 and 1.5 mM sodium silicate on the species performances. The plants cultivated in greenhouse in sand culture with Hoagland nutrient solution. The results showed that the plants growth was reduced in salinity treatment. The plants performances were improved using silicon nutrition (especially 0.75 mM). Salt treatment increased the Na+ and decreased K+, Ca2+ and Fe content in aerial parts of the species, however, silicon treatment led to reducing the Na+ and increasing Fe content. The activities of soluble and cell wall peroxidase and polyphenol oxidase enzymes were declined in the species under salinity. The application of 0.75 mM Si approved to be an effective way to recover the activities of these enzymes. Salinity imposed significant reduction in contents of chlorophylls, total carotenoids and xanthophylls and soluble proteins, however, the hydrogen peroxide rate as well as lipid peroxidation contents were increased. On the contrary, chlorophylls, total carotenoids and xanthophylls and soluble proteins contents were increased and hydrogen peroxide and lipid peroxidation were decreased in salt-treated plants following Si treatment (0.75 mM Si). Salinity caused significant increase in electrolyte leakage from plant membranes; however, silicon nutrition (0.75 mM Si treatment) reduced these parameters. The result indicated that silicon nutrition (especially 0.75 mM treatment), mitigates harmful effects of salinity through declined Na+ content and increased antioxidant enzymes activities that reduced oxidative stress as evidenced by decreased lipid peroxidation and electrolyte leakage. Consequently, Si application led to better growth of salt –affected plants.

Silicon as an essential nutrient in rice plant affects many growth factors including yield. The main object of this study was to evaluate the effects of silicon application on growth, uptake pathways and accumulation of some nutrients and phenolics and lignin contents in rice plant, Oryza sativa cv. Fajr. The plants cultivated in Hydroponic culture medium with Yoshida nutrients in growth chamber under controlled condition. Silicon treatments were included two 0 and 1.5 mM sodium silicate. The plants treated with silicon for 12 days indicated higher fresh and dry weight of shoot, relative growth rate and shoot to root ratio compared to plants devoid of silicon nutrition. In contrast, transpiration was decreased significantly due to silicon application. Also, uptake and accumulation of silicon, iron and potassium were significantly increased and calcium and magnesium uptake and accumulation were markedly decreased following silicon application. Soluble phenolics significantly decreased in roots and shoots of silicon treated plants, while lignin increased in root and decreased in shoot due to silicon application that may related to creation of barrier in apoplastic pathway of nutrients uptake. Measurement of nutrients uptake by reduction of their concentration in nutrient solution following different treatments including 2,4-Dinitrophenol, sodium cyanide and cold in roots environment and saturation of water vapor in shoots indicated that probably silicon deposition in cell wall and vascular space limited apoplastic uptake of calcium. On the other hand, improvement of membranes function increased iron uptake via intracellular pathway.

Puccinellia distans is a perennial grass, which is well adopted naturally in the areas with waterlogged and relatively high salinity. In this research, the growth rates of Puccinellia distans, irrigated with natural water collected from Agh-ghala and Gorgan golf were evaluated using a completely randomized design. The plants were cultivated in Hoagland nutrient solution collected from natural and the two water dilution levels (diluted two and four times in compared with natural collected waters). Gorgan city tap water was used as a control treatment. The plants were harvested after 75 days and the growth rates of the species and Na+, K+, calcium and iron concentration in the plants were measured. The highest growth rate of the species was observed in four times diluted Agh-ghala run off treatment. The total fresh weight and total dry weight of this treatment were 92.4 g and 60 g respectively. The accumulated Na+ content in control treatment was less than other treatments significantly. The accumulated Na+ in the plants irrigated with tap water, Agh-ghala and Gorgan golf were 11.3, 36.7 and 34.3 mg g-1 dry weight respectively. The Potassium concentrations in the plants irrigated with natural saline water collected from the two areas were less than the control treatment (Gorgan tap water) significantly. The potassium concentrations in the plants tissues were increased up to 38.9 mg g-1 dry weight using diluted saline water. Dilution of saline water also leads to increase the iron (20 and 7 folds in Agh-ghala run off and Gorgan golf water treatments) and calcium concentrations (1.5 and 1.1 folds in Agh-ghala run off and Gorgan golf water treatments) in the above ground of the species significantly. According to the results, the growth rates of this species were decreased when the plants irrigated with saline because of ion toxicity and decreasing the potassium, calcium and iron contents in the above ground biomass of the species. This study indicated that this species has capability to be used in the restoration projects of areas with saline and wet soils.