Search

Introduction Groundwater salinization is a major environmental problem, especially in arid and semi-arid regions of the world. Different natural processes and anthropogenic activities can cause groundwater salinity. Factors such as rainfall, evaporation, groundwater pumping, agricultural and industrial activities, and artificial recharge of aquifers can affect the salinity of groundwater. One of the important factors that cause the salinity of freshwater aquifers is natural saline waters. Natural salinization of groundwater has occurred in many regions of the world. This phenomenon has been introduced as "dryland salinity". As a result of this phenomenon, salts accumulate in soil and water and affect human life and natural ecosystems. Several factors cause the natural salinity of groundwater in semi-arid regions. These factors include locally derived cyclic salts, salts in wind deposits, salts in marine deposits, salt domes, unsaturated zone salts and, salts resulting from rock weathering. Delineating the origin and mechanism of salinity is an important help in preventing the degradation of groundwater quality and optimal management of groundwater resources. In recent years, the phenomenon of salinization of groundwater has been observed in some areas of the Faryab plain in southeast Iran. This study aims to identify the origin and mechanism of groundwater salinity in Faryab plain aquifer. Materials and Methods This paper presents an integrated geophysical and hydrochemical investigation of the saline water intrusion into the Faryab plain. Geophysical studies were conducted by the geoelectrical method and include 55 electric soundings. The results of geoelectric studies have been analyzed using iso-resistivity maps and geoelectrical profiles. Twenty-seven water samples were also collected from abstraction wells to assess the quality of groundwater. These samples have been analyzed to determine the concentration of main cations and anions. The results obtained from the chemical analysis of water samples have also been examined and analyzed using spatial distribution maps of qualitative parameters, bivariate diagrams, and time series of water salinity. The mixing rate of saline and fresh groundwater has also been evaluated using ionic ratios of Na/Cl and Cl/HCO3. Results and Discussion The lowest electrical resistance was recorded in the central part of the plain. The specific resistance of the saturated zone decreases towards the center of the plain. Therefore, fresh water and saline water are hydraulically connected. According to the spatial variations of specific resistance, the Faryab plain is divided into two regions: one area with a resistance of more than 50 ohm-m and one region with a resistance of less than 10 ohm-m. The area with low specific resistance (less than 10 ohm-m) is observed in the center of the plain. The most important reasons for the existence of this area are the high groundwater level, the surface saline layers, and the salinity of groundwater. The electrical conductivity of groundwater reaches 64000 μmohs/cm in the center of the Faryab plain. The highest amount of sulfate and chloride ions are also observed in the water samples of this area. According to the Gibbs diagrams, the groundwater has been also influenced by the evaporation process. Conclusion In this study, the origin and mechanism of groundwater salinity in the Faryab plain in southeast Iran were investigated. Fine-grained sediments have been deposited in the central part of this plain. In the past, the underground water level in this area was a little far from the ground level and caused an evaporation zone of surface and underground water. As a result of water evaporation in the central part, evaporative sediments including chalk and salt sediments were formed and the amount of underground water salts increased. Based on the results of geoelectrical studies, in the central areas of the plain, the amount of specific apparent resistance decreases, which indicates the presence of fine-grained sediments containing salt water in these areas. Investigating the quality characteristics of underground water also shows the occurrence of processes such as dissolution of halite, dissolution of gypsum and the occurrence of cation exchange process in the aquifer. Evaporation from underground water has also affected the water quality, especially in the middle part of the plain. As a result of high pumping from the production wells, the hydraulic load of the aquifer has decreased and the saline groundwater zone has expanded towards the production wells. Saltwater intrusion has caused salinity and quality degradation of underground water. According to the results of this research, the most important reason for the salinity of underground water in Faryab plain is excessive extraction of underground water and disturbing the natural balance of the aquifer. The most important solution to deal with the development of the salt water front in the Faryab plain is to reduce the exploitation of the aquifer, especially in its middle areas. It is also suggested to modify and improve existing artificial feeding facilities and locate new artificial feeding projects to control saltwater intrusion. Sampling from different depths of the aquifer and measuring minor ions such as iodine and bromine will greatly help to better understand the groundwater salinization process. Measurement of environmental isotopes such as oxygen-18, deuterium and chloride-36 will also help to enrich future studies. By preparing the mathematical model of the aquifer, the effect of different management measures on the salinity control of the aquifer can be investigated. By using the results of the mathematical model, the aquifer balance can be checked and the amount of underground water withdrawal can be determined. [ABSTRACT FROM AUTHOR]

A factorial experiment has been conducted as a randomized complete block design with three replications at the research fields of Faculty of Agriculture of Tarbiat Modares University, during 2017-2018 growing season. The treatments are consisted of three different levels of salinity stress (control), salinity of 5 and 10 dS.m-1), and two levels of calcium silicate (control and foliar application of 8 kg.ha-1), wherein salinity stress has been applied from the beginning of flowering and calcium silicate, at flowering time. The paper then evaluates dry weight of the plant, grain yield, yield components, harvest index, oil yield, oil percentage, and greenness. Foliar application of calcium silicate shows positive effects on all traits of both Zarfam and Sarigol cultivars, increasing the yield in rapeseed. On the other hand, it can be observed that Sarigol has had more pods, more seeds per pod, as much as 1000 of grain weight, and greater harvest index, oil percentage, oil yield, and greenness index than the Zarfam, which has had the maximum plant dry weight. In addition, it is observed that salinity stress at 5 and 10 dS.m-1 have negative effects on all studied traits in the present study. In general, salinity stress reduces the yield and yield components of rapeseed and the use of calcium silicate reduce the negative effects of salinity stress in both Zarfam and Sarigol cultivars with the latter showing more resistance to salt stress than the fomer, being used more effectively from calcium silicate. [ABSTRACT FROM AUTHOR]

Background and Objectives: Perennial sow-thistle (Sonchus arvensis L.) is a medicinal plant belong to the sunflower family with anti-diabetic, antidepressant and anti-cancer properties. The crisis of salinization of agricultural lands is considered as one of the most important problems of the world and Iran, and as an environmental stress, it has a direct effect on many plant characteristics under stress. Since there is little information about the response of Sonchus plant to salinity stress, the present experiment was conducted to investigate the effect of salinity on some morphological and physiological traits as well as the activity of antioxidant enzymes under salinity conditions. Materials and Methods: The experiment was conducted as a completely randomized design with three repetitions in 2018 in the greenhouse of the Faculty of Agriculture of Urmia University. Salinity stress was applied at four levels (0, 50, 100 and 150 mM of NaCl salt) at the 6-8 leaf stage, and shoot dry weight, root dry weight and root length were recorded. Also, photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids), protein content, relative leaf water content (RWC), proline and carbohydrate contents, antioxidant capacity (DPPH and FRAP) and the activity of antioxidant enzymes including catalase (CAT), ascorbate peroxidase (APX), superoxide dismutase (SOD), peroxidase (PX) were measured in the lower and middle leaves of the plants. Analysis of variance (ANOVA) for the obtained data and comparison of the means of the treatments using Duncan’s test were implemented in SAS 9.4 software. Results: The results showed that root length, root dry weight and shoot dry weight decrease significantly with increasing salinity level. Also, the content of chlorophyll a and b increased in salinity conditions, while salinity decreased the amounts of carotenoids. The highest amount of chlorophyll was observed in the lower leaf under 150 mM NaCl. The content of protein, proline and soluble sugar was enhanced with increasing salinity level; the maximum amount of these parameters was observed in the middle leaf at 150 mM NaCl. The highest amount of total phenolic and flavonoid compounds was observed at the stress level of 50 mM NaCl. The content of sodium ion (Na+) increased with increasing salinity level, while the amount of potassium ion (K+) declined. The activity of superoxide dismutase, catalase, peroxidase and ascorbate peroxidase enzymes, as well as FRAP and DPPH antioxidant capacity increased in salinity conditions. Conclusion: According to the obtained results, it can be concluded that Sonchus arvensis plant copes with salinity through increasing some osmolytes under stress conditions. Moreover, an enhancement of the amount of chlorophyll a and b at high levels of salinity showed that Sonchus arvensis is probably a salt-tolerant plant. [ABSTRACT FROM AUTHOR]

Turbidity is significant contributors to declines in populations of aquatic organisms. The aim of the present study was to investigate the effects of different levels of water turbidity on the growth performance, immune and antioxidant response of Rutilus caspius. A total number of 360 Caspian roach (with average weight 0.75±0.052 g) randomly in 4 treatments and 3 repetitions in 12 tanks with concentrations of 0, 250, 500, 1000 mg L−1 (C0, C1, C2 and C3 respectively) was distributed for 40 days. Then the fish were subjected to salinity stress (13 g L-1 ) for 48 hours. The results showed that water turbidity significantly decreased growth performance and feed efficiency (P<0.05). Total immunoglobulin and lysozyme activity in the control had a significant increase compared to other treatments (P<0.05). Cortisol concentration in turbidity of 500 and 1000 mg SS L−1 (C2 and C3) had a significant increase compared to other experimental treatments (P<0.05). Water turbidity significantly decreased tissue superoxide dismutase and glutathione peroxidase, but increased tissue malondialdehyde concentration (P<0.05). Based on the obtained results, water turbidity with concentrations of 500, 1000 mg L−1 can reduce the physiological response and resistance of Rutilus caspius against salinity stress. [ABSTRACT FROM AUTHOR]

IntroductionGroundwater salinization is a major environmental problem, especially in arid and semi-arid regions of the world. Different natural processes and anthropogenic activities can cause groundwater salinity. Factors such as rainfall, evaporation, groundwater pumping, agricultural and industrial activities, and artificial recharge of aquifers can affect the salinity of groundwater. One of the important factors that cause the salinity of freshwater aquifers is natural saline waters. Natural salinization of groundwater has occurred in many regions of the world. This phenomenon has been introduced as "dryland salinity". As a result of this phenomenon, salts accumulate in soil and water and affect human life and natural ecosystems. Several factors cause the natural salinity of groundwater in semi-arid regions. These factors include locally derived cyclic salts, salts in wind deposits, salts in marine deposits, salt domes, unsaturated zone salts and, salts resulting from rock weathering. Delineating the origin and mechanism of salinity is an important help in preventing the degradation of groundwater quality and optimal management of groundwater resources. In recent years, the phenomenon of salinization of groundwater has been observed in some areas of the Faryab plain in southeast Iran. This study aims to identify the origin and mechanism of groundwater salinity in Faryab plain aquifer. Materials and Methods This paper presents an integrated geophysical and hydrochemical investigation of the saline water intrusion into the Faryab plain. Geophysical studies were conducted by the geoelectrical method and include 55 electric soundings. The results of geoelectric studies have been analyzed using iso-resistivity maps and geoelectrical profiles. Twenty-seven water samples were also collected from abstraction wells to assess the quality of groundwater. These samples have been analyzed to determine the concentration of main cations and anions. The results obtained from the chemical analysis of water samples have also been examined and analyzed using spatial distribution maps of qualitative parameters, bivariate diagrams, and time series of water salinity. The mixing rate of saline and fresh groundwater has also been evaluated using ionic ratios of Na/Cl and Cl/HCO3. Results and Discussion The lowest electrical resistance was recorded in the central part of the plain. The specific resistance of the saturated zone decreases towards the center of the plain. Therefore, fresh water and saline water are hydraulically connected. According to the spatial variations of specific resistance, the Faryab plain is divided into two regions: one area with a resistance of more than 50 ohm-m and one region with a resistance of less than 10 ohm-m. The area with low specific resistance (less than 10 ohm-m) is observed in the center of the plain. The most important reasons for the existence of this area are the high groundwater level, the surface saline layers, and the salinity of groundwater. The electrical conductivity of groundwater reaches 64000 μmohs/cm in the center of the Faryab plain. The highest amount of sulfate and chloride ions are also observed in the water samples of this area. According to the Gibbs diagrams, the groundwater has been also influenced by the evaporation process. Conclusion In this study, the origin and mechanism of groundwater salinity in the Faryab plain in southeast Iran were investigated. Fine-grained sediments have been deposited in the central part of this plain. In the past, the underground water level in this area was a little far from the ground level and caused an evaporation zone of surface and underground water. As a result of water evaporation in the central part, evaporative sediments including chalk and salt sediments were formed and the amount of underground water salts increased.Based on the results of geoelectrical studies, in the central areas of the plain, the amount of specific apparent resistance decreases, which indicates the presence of fine-grained sediments containing salt water in these areas. Investigating the quality characteristics of underground water also shows the occurrence of processes such as dissolution of halite, dissolution of gypsum and the occurrence of cation exchange process in the aquifer. Evaporation from underground water has also affected the water quality, especially in the middle part of the plain. As a result of high pumping from the production wells, the hydraulic load of the aquifer has decreased and the saline groundwater zone has expanded towards the production wells. Saltwater intrusion has caused salinity and quality degradation of underground water. According to the results of this research, the most important reason for the salinity of underground water in Faryab plain is excessive extraction of underground water and disturbing the natural balance of the aquifer. The most important solution to deal with the development of the salt water front in the Faryab plain is to reduce the exploitation of the aquifer, especially in its middle areas. It is also suggested to modify and improve existing artificial feeding facilities and locate new artificial feeding projects to control saltwater intrusion. Sampling from different depths of the aquifer and measuring minor ions such as iodine and bromine will greatly help to better understand the groundwater salinization process. Measurement of environmental isotopes such as oxygen-18, deuterium and chloride-36 will also help to enrich future studies. By preparing the mathematical model of the aquifer, the effect of different management measures on the salinity control of the aquifer can be investigated. By using the results of the mathematical model, the aquifer balance can be checked and the amount of underground water withdrawal can be determined.

Background and Objectives: Plant growth-promoting rhizobacteria (PGPR) are soil bacteria that colonize the rhizosphere of plants, enhance plant growth and may alleviate environmental stress, thus constituting a powerful tool in sustainable agriculture. In the present study, we compared the effect of selected PGPR strains on growth promotion and alleviating the salinity stress in liquorice (Glycyrrhiza glabra L.) plants. Materials and Methods: An in vitro experiment was designed with two factors: salinity (control without salinity (NS), 60 mM (S1), 120 mM (S2) and 180 mM (S3)) and PGPR inoculation (control without inoculation, inoculated with Pseudomonas fluorescens, inoculated with Pseudomonas putida and inoculated with Azotobacter chroococcum). 15-day-old inoculated or non-inoculated seedlings were grown in jars containing MS plant growth medium and NaCl treatments. Plants were grown in the growth chamber for 35 days and then assessed. Fresh weight, dry weight, length of root and shoot, photosynthetic pigments, proline, malondialdehyde and some antioxidant enzymes were evaluated. Results: Salinity decreased liquorice growth, regardless of the PGPR treatment and the salt stress level. The plants inoculated with P. fluorescens had significantly greater shoot biomass than the control plants at all salinity levels, whereas the A. chroococcum inoculation only was effective in increasing shoot biomass at the higher salinity level and P. putida had no significant effect on shoot growth. Root length decreased in all bacterial treatments under salinity. P. fluorescens treatment showed a significant and increasing effect on root length at all salinity levels. The salt tolerance index was significantly higher in PGPR-inoculated plants at 120 and 180 mM NaCl. The effect of P. putida was more significant in the improvement of total chlorophyll content rather than other species. Salt stress induced malondialdehyde (MDA) and proline production in both inoculated and non-inoculated plants, however inoculation with Pseudomonas species significantly reduced MDA content and increased proline content, especially at 60 and 120 mM NaCl treatments. Moreover, the activity of superoxide dismutase and guaiacol peroxidase raised significantly, as the salt level increased. PGPR inoculation induced a higher increase in these antioxidant enzyme activities at all salt levels. The salinity stress decreased the concentration of K and K/Na ratios. Bacterial inoculation significantly increased K concentration under severe salinity stress and promoted a higher K/Na ratio. Conclusion: Inoculation with all PGPR species at 120 and 180 mM NaCl led to the enhancement of salinity tolerance of liquoric through increased production of proline and antioxidant enzymes and maintaining a higher K/Na ratio. Results indicate that inoculation with selected PGPR, especially Pseudomonas species could serve as a useful tool for alleviating salinity stress in liquorice. [ABSTRACT FROM AUTHOR]

Objective Salinity stress is one of the most important environmental stresses that significantly has negative effects on plant growth and crop production all over the world. Among cereal crops, barley (Hordeum vulgar L.) is the most tolerate cereal to abiotic stresses, especially to salinity stress. In the present study, to evaluate the molecular response of some promising genotypes of barley to salinity stress, the expression patterns of APX, GPX, SOD, Rbohf1, and Rbohf2 genes were assessed under two control and salt stress conditions. Materials and methods In this study, the effect of salt treatment (200 mM NaCl) on relative expression patterns of APX, GPX, SOD, Rbohf1, and Rbohf2 genes in a set of six promising genotypes of barley along with a local cultivar as the reference genotype (cv. Mehr) was evaluated. The experiment was conducted in a randomized complete block design in two environments (normal and saline stress) under controlled glasshouse conditions using a hydroponic system. After seedling establishment and applying stress treatment (21-days), plants were subjected to sampling and the relative expression for targeted genes was estimated as proposed by Pfaffl (2001). Results According to the results, a significant difference was observed between control and salt treatments, as well as, among tested barley genotype in terms of all investigated genes. Salt treatment significantly increased expression of Rbohf1, APX, GPX, Rbohf2, and SOD by 6.80, 4.51, 4.26, 2.76, and 2.72-fold compared to control treatment, respectively. A comparison of the expression patterns of studied genes revealed that promising genotypes G6 and G7 showed better tolerance against oxidative stress induced by salt treatment and revealed an acceptable tolerance to salinity stress. Conclusions Our results revealed that the genotypes G6 and G7 due to their genetic background have a high potential to the regulation of their antioxidant system. Hence, these genotypes can be used as ideal candidates for supplementary studies and even participate in adaptability and stability trials to release as commercial cultivars tolerant to salt stress. [ABSTRACT FROM AUTHOR]

Background and Objectives: 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. Materials and Methods: 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 2019. 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. Results: 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. Conclusion: 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. [ABSTRACT FROM AUTHOR]

This study was conducted to investigate the effect of salinity caused by sodium chloride on the content of ions and understand the level of resistance in four varieties of Canola (Brassica napus L.) namely Talaye, Sarigol, Zarafam, and Opera. The plants were grown in hydroponic solution (1/4 strength Hoagland solution) and greenhouse conditions. When the plants reached the 5-leaf stage, they were treated with concentrations of 0 (control), 50, 75, and 100 mM sodium chloride for 14 days and then harvested. In order to measure the content of nutritional elements of the plant organs, extracts of the desired organs were prepared. The results of the experiments showed that with increasing salinity, the potassium content of shoots and roots decreased in all 4 cultivars in response to salinity stress, while the content of chlorine and sodium increased. The highest increase of chlorine and sodium elements in response to salinity stress was observed in Talaye and Sarigol cultivars, about 1000 times more than the control plants. The increase in the sodium content of the shoot was higher than that of the root and it increased about 800 times in the roots of Talaye and Sarigol cultivars, it increased about 800 times. Proline and glycine betaine contents of leaves increased in response to salt stress. The amount of soluble sugar in shoot and root also increased in some cultivars, so in the treatment of 100 mM, its amount in the leaves of Talaye variety increased by 43% and in Sarigol by 80%. According to the obtained results, it can be concluded that among the cultivars studied, Opera and Zarafam cultivars have better performance under salt stress than the other two cultivars, and the performance of Sarigol is weaker than other cultivars. [ABSTRACT FROM AUTHOR]

Photosynthesis is one of the most important physiological processes that is negatively affected by salinity stress in plants. Nitric oxide is known as an influential signal molecule in plant responses to environmental stresses. The tomato plant (Lycopersicon esculentum L.) contains a wide range of vitamins and nutrients that are economically and nutritionally important. In the present study, the effects of different levels of salinity stress including 0, 50, 100 and 150 mM NaCl and sodium nitroprusside (SNP) at 0, 100 and 200 pM levels on different photosynthetic parameters were investigated by JIP test. The results of this study showed that salinity stress reduced the efficiency of the oxygen-evolving complex in photosystem II. Salinity reduces the efficiency of light reactions of the photosystem II (tpPo/(1-(pPo)) and the efficiency index of active reaction centers (yrc/(1-yrc)). Furthermore, the efficiency of biochemical reactions of electron transport (Vo/(1-Vo)) and the efficiency index of reduction of the end electron acceptor in photosystem I (5ro/(1-5r٠)) decreased with salinity stress. The results also revealed that salinity stress reduced the overall performance of the photosynthetic apparatus from the beginning of photosystem II to the end of photosystem I (PITotal). Salinity stress reduced photosynthetic pigments, including chlorophyll a, chlorophyll b and total chlorophyll, and a significant increase in total carotenoids, total polyphenolic content and total flavonoid were observed under salinity stress. The use of SNP as a nitric oxide donor mitigated the effects of salinity stress in all the mentioned parameters. The results of this study showed that in the photosynthetic apparatus of the tomato plants, the electron transport chain is the most sensitive point to salinity stress and 100 pM SNP is the most effective concentration to alleviate the effects of salinity stress. [ABSTRACT FROM AUTHOR]

Introduction: Milky thistle (Silybum marianum) is an annual or biennial plant of the Asteraceae family. Possibly native near the coast of southeast England, it has been widely introduced outside its natural range, for example into North America, Iran, Australia and New Zealand where it is considered an invasive weed. Seed is an important stage of plant life history. Most invasive plants primarily rely on seedling recruitment for population establishment and persistence. The rapid spread of many invasive plants is frequently correlated with special seed traits. Seed trait variations exist not only among species but also within species. Seed traits variations within a species are essential for the seedling establishment at different habitats. Environmental factors, such as temperature, soil solution osmotic potential, solution pH, light quality, management practices and seed location in the soil seedbank, affect weed seed germination and emergence. Fluctuations in temperature can influence seed germination differently than those under constant temperatures; however, such information is not available on Milky thistle. A light requirement for germination is the principal means by which germination can be restricted to an area close to the soil surface, and species requiring light for germination are potentially more likely to be prevalent in no-till and pasture systems. Soil pH affects the development and competitiveness of crops and weeds by affecting the availability of essential minerals, nutrients, the solubility of toxic elements, and soil microflora. Seed burial depth (buried by tillage or other means) also affects germination and seedling emergence of several weed species. Better knowledge of the factors that influence seed germination and seedling emergence of Milky thistle could contribute to the development of control measures and help determine its potential for invasion into new areas. The objectives of this study, therefore, were to determine the effect of various environmental factors on seed germination and seedling emergence of Milky thistle. Material and Methods: Germination of Milky thistle was determined by placing 25 seed in a 9-cm-diam Petri dish containing two layers of Whatman No. 1 filter paper and moistened with 5 ml of distilled water or a treatment solution. Temperature: Germination of freshly harvested seed was determined in growth chambers under fluctuating day/night temperatures (15/5, 20/10, 15/25, 15/30 and 20/35˚ C). Salinity: In this experiment, seeds were exposed to seven levels of increasing salinity using NaCl solutions including 0, 10, 20, 40, 80, 160 and 320 mM. Petri dishes were incubated as described in the general protocol under the light⁄dark regime. pH: To examine the effects of pH on seed germination, buffered solutions of pH 5 to 9 were prepared. Seed burial depth: The effect of different burial depths on seedling emergence was investigated in a growth chamber. Seeds were buried at six different depths (0, 0.5, 1, 2, 4, and 8 cm) in 15-cm-diam plastic pots. Statistical analysis: Data were subjected to two-way analysis of variance (ANOVA) and the difference between treatment means was separated using FLSD test. A significance level of 5% was applied by SAS 9.2. Results and Discussion: The results showed that effect of different temperature regimes on germination percentage and rate, plumule length and seedling dry weight were significant (P

Introduction: Soil salinity is one of the major limitations of agriculture in the warm and dry regions. Soil sodification also damages soil structure and reduce soil permeability. Therefore, control of soil salinity and sodium is very important. Vetiver grass has unique characteristics that can be useful in phytoremediation. Materials and Methods: This research was conducted to investigate the effects of irrigation with different salinities on vetiver grass and the effects of this plant on the control of soil salinity and soil reclamation.The experimental design was randomized complete block design. Irrigation water salinities were 0.68(blank), 2, 4, 6, 8 and 10 dS/m, respectively, which artificially were constructed using sodium chloride and calcium chloride. At first, vetiver was transplanted and then moved to the farm. The amount of soil moisture was measured by the neutron probe. Irrigation depth was applied to refill soil water deficit up to field capacity. To evaluate the soil salinity in above salinity treatments, soil was sampled in each plot from 0-30, 30-60 and 60-90 cm depths and for each layer, electrical conductivity of saturated extract (ECe), sodium, potassium and chloride concentrations was measured .To measure the sodium, potassium and chloride concentrations in the leaves and roots of vetiver plant, samples were dried in oven. The dried samples were powdered and passed through the sieve (No. 200) and they were reduced to ash in 250 ◦C. 5 ml HCl was added to one gram of the ash, and after passing through filter paper, the volume of sample was brought to 50 ml by boiled distilled water. After preparing plant samples, the sodium, potassium and chloride concentrations were measured by Flame Photometer. Reults and discussion: The results showed that the vetiver grass was able to decrease soil salinity at different salinity levels except highest water salinity (10 dS/m) and prevented salt accumulation in the soil. However, in the salinity 10 dS/m, soil salinity was not well controlled, but soil salinity was lower than the irrigation salinity. In these water salinities, the mean ECes in 0-90 cm soil depth were increased 25.0, 60.4, 79.2, 87.5 and 215.5 percent, respectively, relative to a control treatment, which was much less than the increasing of irrigation water salinities. These increases in ECe were significant at 5% level of probability. The accumulated values of sodium in vetiver leaves showed significant difference between S0 treatment and the other treatments (S3, S4 and S5) at the 5% level of probability. The sodium contents in vetiver leaves were 22.2, 33.3, 70.4, 103.7 and 122.2% and in vetiver roots were 32.7, 66.5, 129.3, 218.2 and 281.8% higher than the control treatments (S0), respectively. Sodium contents in vetiver roots were 103.7, 121.2, 154.4, 174.1, 218.2 and 250% more than sodium contents in vetiver leaves in S0, S1, S2, S3, S4 and S5 treatments, respectively. Sodium contents were increased 14.3, 28.6, 64.3, 100.0 and 114.3 percent in vetiver leavesand 28.6, 64.3, 125.0, 214.3 and 275.0 percent in the vetiver roots , relative to the control treatment, respectively, at above salinity levels, which indicated an improvement of sodium accumulation in leaves and roots with increasing salinity levels. Chloride concentrations at irrigation water salinities S1, S2, S3, S4 and S5 treatments (2-10 dS/m) were 22.9, 35.6, 74.5, 107.2 and 121.9% in vetiver leaves and 27.02, 59.7, 118.9, 195.06 and 255.7% in vetiver roots more than control treatment, respectively. The mean values of sodium and chloride in all salinity levels in the roots were 170.3 and 164.1 percent more than the leaves, respectively.There were no significant differences in accumulated potassium in vetiver leaves and roots between different treatments, but vetiver leaves and roots absorbed and accumulated high value of potassium. The potassium contents were 4.38, 4.64, 4.18, 3.89, 3.82 and 3.68 mg/g in vetiver leaves and 3.12, 3, 3.62, 3.69, 3.84 and 3.68 mg/g in vetiver roots, in S0, S1, S2, S3, S4 and S5 treatments, respectively. Conclusion: In general, the results showed that up to irrigation water salinity 8 dS/m, Vetiver grass had very good ability to control soil salinity and prevented the accumulation of salt in the soil, but at the salinity of 10 dS /m, soil salinity was not well controlled. However, in 10 dS /m, soil salinity was much less than water irrigation salinity. The mean values of soil salinity in layer 3 (60-90 cm) were 0.48, 0.6, 0.77, 0.86, 0.9 and 1.5 dS/m in S0, S1, S2, S3, S4 and S5 treatments, respectively. ECes were 29.4, 70.0, 80.8, 85.7, 88.8 and 85.0 percent lower than irrigation water salinities 0.68, 2, 4, 6, 8 and 10 dS/m, , respectively. Sodium and chloride accumulated in the leaves and roots of vetiver that showed that Vetiver it is well able to absorb these elements. The accumulations of sodium and chloride in roots were170.3 and 164.1 percent more than leaves, respectively.

In this paper, the effect of NaCl on the activity of soluble (SPO) and wall bound peroxidases (IPO, CPO) as well as the level of lipid peroxidation in roots of two cultivars of wheat (Triticum aestivum L.) were studied. Two wheat cultivars, Mahooti and Alamoot were selected as salt-tolerant and salt-sensitive cultivars, respectively. The plants were treated with 300mM NaCl for 24, 48 and 96 hours. The content of lignin and the ratio of CWP/FW were studied during 96 hours of treatment as well. Salt treatment increased the rate of lipid peroxidation and enhanced the activity of wall bound peroxidases, particularly in roots of Mahooti. These phenomena were also associated with an increase in the content of lignin in the walls. The activity of soluble peroxidase was also stimulated which helps to more scavenging of peroxide radicals produced by NaCl treatment. Meanwhile, the results suggest that in salt-tolerant wheat cultivar, NaCl treatment accelerated aging process.

In a randomly and factorially designed experiment, the interaction effects of dietary zeolite (0 and 2%) and three salinity levels (80, 130 and 180 ppt) on growth, survival, reproductive performance and total longevity of A. franciscana were determined (6 treatments in total). The experiment was carried in two stages: nauplius to maturity and maturity to death of all females. The results indicated that the total body length of Artemia fed with zeolite were not significantly different among treatments in the third week of rearing (P>0.05), except for nauplii fed zeolite in salinity 180 ppt. However, Artemia fed with zeolite in 80 ppt had a higher body length and furcal length compared with other treatments. Nauplii in all treatments reached sexual maturity within 17-23 days (P>0.05). Survival rate was far higher in groups fed with zeolite compared to unfed groups; the highest values were recorded in group fed with zeolite at the salinity 130 ppt (P<0.05). The reproductive period and total longevity of females decreased with increasing salinity, but this trend was not affected by diet type. Average offspring production in the groups fed with zeolite was in the range of 861-1160 offspring compared to unfed groups (604-741 offspring) (P<0.05). The encysted embryos percentage was different in the range of 20-35%. According to the results, the inclusion of 2% zeolite in salinity within 80-130 ppt were better for growth of the Artemia to maturity. Also, it is recommended to add zeolite in the Artemia diet with the increasing trend in salinity from 80 to 180 ppt for improving broodstock reproductive performance. [ABSTRACT FROM AUTHOR]

Background and Objectives: Due to population intensity and industrial activities, quality of groundwater is important in Bushehr province and in particularly in coastal areas. The salinity of groundwater in Asaluyeh plain is increasing from the heights towards the Persian gulf and in some places are not even applicable for irrigation. Materials and Methods: In order to explore the source of the chloride anomaly, groundwater samples were analyzed and compared with the Persian Gulf samples. Also Water Samples Different diagrams were determined and the reasons of water salinity of Asaluyeh Plain were investigated. Results: The results of chemical analyses showed the groundwater excessive salinity, especially near the sea. Based on correlation matrix, the highest correlation between the sodium and chlorine ions was observed. Conclusion: The factors influencing on groundwater salinity in the plain varies and arising from solution of halite and gypsum from surrounding formations, suddenly increas sodium chloride in some parts of plain and forming Cl-Na water type. The results indicated that the Groundwater Type of Asaluyeh is Cl-Na and therefore it is classified as non-potable water. [ABSTRACT FROM AUTHOR]

Poplar grows fast and can be used as row material in industry, pulp for paper, lumber and building products and as buffer strips to conserve plantation. Salinity has a major impact on plant growth and productivity. As tolerance of various poplar species to salinity is variable and imprecise, an experiment was conducted to evaluation different levels of sensitivity to salinity which consisting of factorial combination of 4 clones and 5 treatment {0.0 (control) 0.32%, 0.64%, 0.96% and 1.28%} of NaCl and CaCl2 with tree replications in a greenhouse in Shehid Fozveh Research Station of Esfahan Province from 1377 to 1379. Poplar clones include Populus nigra 63/135, P.deltoides 79/51, P. alba 44/9 and P. euramericana var. triplo. Salinity treatments were imposed by adding NaCl and CaCl2 (2:1molar ratio) to half concentration Hogland Nutrition solution that ranged from 0 to 1.28% m/v percent .Result of this experiment showed that number of leaf, dry weight of leaves, stems and roots were decreased with increasing salinity. With increasing salinity, amount of Na+, Ca²+, Cl- and K+ were increased. P.euramericana var. triplo and P.deltoides 79/51 growth had most reduction rate. P.alba 44/9 showed higher tolerance compare to the others.