فهرست مطالب

دانش آب و خاک - سال بیست و پنجم شماره 4 (زمستان 1394)
  • سال بیست و پنجم شماره 4 (زمستان 1394)
  • تاریخ انتشار: 1394/11/13
  • تعداد عناوین: 21
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  • M. Kazemzadeh, A. Malekian* Pages 1-12
    Nowadays, with a growing population and the increasing trend of recent droughts, scientific attention to the mentioned drought phenomenon is inevitable. In this study the Stream flow Drought Index (SDI) was used for analyzing the hydrological droughts over the last three decades in the northwest of Iran (Ardebil province). The periods of 3, 6, 9, and 12 months and also 5 and 10 years were selected for the spatiotemporal monitoring of the hydrological droughts. The temporal drought analysis showed that the most of drought events over the reference periods have occurred in the last 15 years. In other words, there was an approximately normal status in the most of stations in the first study period of 15 years. The most severe hydrological droughts occurred in the Poleh Almas and Poleh Soltani on the Balokhlo-Chai and Khiav-Chai gauging stations, respectively, at the 3- and 6-month scales in 2010. The results revealed that the most severe hydrological drought periods occurred in 2010.
    Keywords: Discharge, Drought impacts, Northwest of Iran, SDI
  • B. Khoshrou, Mr Sarikhani*, N. Aliasgharzad Pages 13-26
    The benefits of biofertilizers in agriculture depend on the use of effective strains with desirable motivating plant growth characteristics. The quality control of the biofertilizers, especially in terms of investigating and proving the genus and species of the bacteria used in them is one of the most important criteria. Therefore, in this study, isolates of the four types of common nitrogen and phosphate biofertilizers in Iran, including Barvar2 (Ba1 and Ba2), Biosuperphosphate (Bio1, Bio2, Bio3 and Bio4), Supernitroplus (Sn1 and Sn2) and Nitroxin (N1, N2, N3, N4 and N5) were studied for the correctness at the genus and species levels. The molecular identification method was applied based on amplifying the 16S rDNA genes using universal primers 27F and 1492R. Also, the bacterial genus and species used in the biofertilizers were determined by proper biochemical tests. The results showed that the isolates N1, N5, Sn2 and Bio3 had a similar phenotype and all of them belonged to the Pseudomonas genus. Also, the Sn1 and Bio4 isolates had morphological and molecular similarities belonging to the Bacillus genus. The results of identification for the isolates Ba1, Ba2, Bio2, N2, N3 and N4 showed that they were Pantoea, Pseudomonas, Acinetobacter, Pseudomonas, Citrobacter and Pseudomonas, respectively. Among the isolates, the presence of Citrobacter (N3) and Acinetobacter (Bio2) in the Nitroxin and Biosuperphosphate biofertilizers were noticeable, because they had not been reported by manufacturers in ingredient of the mentioned biofertilizers. However, contrary to the Nitroxin and Supernitroplus biofertilizers manufacturers’ claim about using two isolates Azotobacter and Azospirillum, the present study indicated the lack of these bacteria in these biofertilizers.
    Keywords: Barvar, Biofertilizer, Molecular, biochemical identification, Nitroxin, PGPR
  • M. Esmaeili Varaki*, Ss Saadati Pacheh Kenari Pages 27-39
    After construction of bridge pier in a river, eddy flow pattern forms around the piers and erosion of bed material and scouring occur, and if foundation depth or piles depth is insufficient, the bridge will be collapsed. In this research, effects of the installation angles of piers group on scour dimensions under different hydraulic conditions and top levels of foundation installation were investigated experimentally. The model of bridge piers group was placed on a rectangular foundation with 3 angles of installation (vertical, degrees of 28, 38 and 45). Experiments were conducted under two different relative velocities (ratio of flow velocity to corresponding inception of motion velocity, 0.8 and 0.95) and three relative levels of foundation (ratio of top level of foundation to width of it, zero, -0.5 and -1). Comparison of the results showed that at zero relative level of foundation, the top level of foundation played as collar and the minimum scour occurred at the vertical installation angle. At the other relative levels of foundation and among the different installation angles of the piers, the angles of 28 and 38 had the maximum and minimum scour depths respectively. Furthermore, variation of the maximum length of scour had a similar trend to the scour depth.
    Keywords: Bridge Pier Group, Foundation level, Installation angle, Scour
  • Ali Afshari*, Hosein Khademi, Mohammad Amir Delavar Pages 41-52
    The study area is about 2000 km2 which is important in terms of agriculture, industry and residential complexes. For the purpose of evaluation, 241 samples of surface soil were taken based on systematic nested method from the land soils in the depth of 0 to 10 cm that were under agriculture, pasture and urban uses. The total concentrations of heavy metals of the samples were determined by an atomic absorption spectrometer following the extraction with 5N nitric acid. The results showed that the total amounts of lead, zinc, cadmium and copper in the soil of the studied area were 1.6, 2.0, 4.0, and 1.5 times higher than those in the soil of the natural background respectively. The total concentrations of iron, manganese, chromium, cobalt and nickel in samples were less than those in the background soil. Based on the contamination factor, in the most of samples, concentration of the iron, manganese, chromium, cobalt, nickel and copper were in low to moderate and Pb concentration in 10% of the samples was in high contaminated classes. More than 40 percent of the area was highly polluted with Cd. High levels of contamination factor for lead, zinc, cadmium and copper (Group I) were found in urban land area and contaminated soils with iron, manganese, chromium, cobalt, and nickel (Group II) were observed in agricultural and pasture lands. Overlaying the maps of contamination factors with those of land uses showed that the first group of heavy metals were mostly affected by human activities and the second group by parent materials.
    Keywords: Background concentration, Cadmium, Contaminated classes, Urban uses, Zanjan
  • Navid Hooshangi, Ali Alesheikh, A. Nadiri* Pages 53-66
    Network Optimization of existing Piezometers number for estimating groundwater levels, since it reduces maintenance cost and saves the charge of data acquisition, is an important step. The main goal of this research is to optimize the number of piezometers to estimate groundwater levels in the unconfined aquifer of Tabriz plain. That was accomplished at three main stages. At the beginning, ground water levels in 75 piezometers of the unconfined aquifer of Tabriz plain were obtained and the performances of five different interpolation methods were evaluated. At this stage, results of the Universal Kriging method with Root Mean Square Error (RMSE) of 1.12 m was selected as an appropriate surface. At the second stage, two methods; including Cross-Validation Error and Principal Component Analysis (PCA) were applied to remove some points. Finally, with respect to RMSE of the created surfaces, the two applied methods were compared. The results showed that by assuming reasonable error threshold (11%) in PCA method, 30 points were removed and the RMSE of the estimated surface increased by14 percent. In the cross validation method by removing 30 other points, the RMSE of the created surface increased by 16.5 percent. Therefore, RMSE changes using PCA compared to cross-validation error method were less, and therefore PCA result was more valid. The results indicated that, by eliminating 30 piezometers from the groundwater level monitoring network of the unconfined aquifer of Tabriz plain, the suitable accuracy for groundwater level estimating could be achieved by increasing the accuracy of water level measurement in the rest of the piezometers that would cause the saving of time and cost.
    Keywords: Groundwater, Interpolation, Piezometers, Principal Component Analysis, Tabriz aquifer
  • Tahereh Raiesi *, Alireza Hoseinpour Pages 67-80
    Rhizosphere region soils have different chemical and biological properties from bulk soils. Information about phosphorus (P) release in the rhizosphere region soil of bean is limited. Therefore, the objective of this research was to evaluate the effects of bean (Phaseolus vulgaris L.) rhizosphere on P release kinetics in 9 types of calcareous soils from Chaharmahal-Va-Bakhtiari province under greenhouse conditions in a rhizobox. The kinetics of P release in the bulk and the rhizosphere region soils were determined by successive extractions with 0.5 M NaHCO3 in a period of 2 to 1008 h at 25 ± 1°C. The results of kinetics study showed that the mean amount of the extracted P after 1008 h in the extraction period in the rhizosphere region soils (215 mg kg-1) was significantly lower than that in the bulk soils (226 mg kg-1). The release kinetics of P from the rhizosphere region and bulk soils could be defined well by use of the first order, power functions and also, the simplified Elovich equation. The results showed that the amount of the P released after 1008 h and the constant P release rate in power function of the rhizosphere region and the bulk soils had a significant correlation with bean plant growth indices. This research indicated that bean rhizosphere could modify the P release characteristics. In addition, the released P amount and rate are important factors in supplying available P to plants.
    Keywords: Kinetics equations, Phosphorus, Rhizobox, Rhizosphere, Successive extraction
  • Ramin Mansori, Hasan Torabi* Pages 81-95
    In this research, the differential evolution algorithm (DE) is used to optimize Ismail Abad water distribution network. This network is a pressurized network and includes 18 pipes and 19 nodes. Optimization of the network has been conducted by developing an optimization model based on the DE algorithm in MATLAB by establishing a dynamic connection with EPANET software for hydraulic calculation of the network. The developed model was run for decision variables including the scale factor (F), the crossover constant (Cr), initial population (N) and the number of generations (G) and their values for the best adeptness of DE algorithm were identified as 0.6, 0.5, 100 and 200, respectively. The optimal solution was compared with the classical empirical method and results showed that implementation cost of the designed network by the DE algorithm was 10.66% lower than that by the classical empirical method.
    Keywords: Crossover constant, Differential evolution algorithm, Optimization, Scale factor, Water distribution network
  • Alireza Afzalian, Javad Ahadian* Pages 97-107
    Piano Key weirs (PKWs) are appropriate alternatives to linear overflow weirs, because of increasing the discharge at the unit length of the unregulated spillway inlet in identical heads and spillway widths. The purpose of this study was to investigate the effect of angled Parapet Wall on the discharge flow and water level upstream piano key weirs and its comparison with the discharge on ogee weirs. To achieve this goal, a Piano Key Weir was constructed as a laboratory model with a constant height of 30 cm and Parapet Wall with positive slopes of 3, 5.5 and 8 degrees in a laboratory flume with 80 cm width, 10 m length and 60 cm height. The results indicated that among the models of Parapet Walls the one with slope of 8 degrees had the greatest impact on the upstream water level of the weir. This increasing relative to the model without Parapet Wall was about of 10 percent. Also, the results showed that at the angle of 8 degrees, the Parapet Wall had lower discharge flow efficiency, as compared to the same at the angles of 3 and 5.5 degrees; but still it was 40 percent more than the discharge flow of the ogee weirs. However, the Parapet Walls with 5.5 and 3 degrees angles led to 7 and 3 percent increase in water level, respectively, compared to the model without Parapet Wall. In addition, the Parapet Wall with 5.5 and 3 degrees angles in comparison to the ogee weirs showed 72% and 140% increase in the discharge flow, respectively. Moreover, it was obtained that the increase of discharge efficiency with increase of Parapet Wall height could occurre up to a specific height.
    Keywords: Angled parapet wall, Increase of water level, Labyrinth weirs, Ogee weirs, Piano Key Weirs
  • Asghar Asghari Moghaddam, Elham Fijani*, Amir Hosein Nazemi Pages 109-122
    The aim of this study is to assess the hydrochemical characteristics of the groundwater system of Maragheh-Bonab plain aquifer, its contamination and effective factors on it. For this purpose, graphical methods and also water quality index (WQI) are used. The study area contains three major groundwater types, namely Ca–Mg–HCO3, Na–Cl, and non-dominant water types based on Piper diagram. Considering the water quality index, there is an evolutionary trend in the water resources in the study area, such that the mixing process of the excellent and poor classes’ waters has caused degradation of water quality from recharge to discharge areas. However, there are some areas in the south of the plain with poor WQI which are affected by polluted wastewater. Industrial factories are located in the recharge area, and in this research, the effect of industrial wastewater on the quality of groundwater has been considered. The electric conductivity of wastewater is very high and based on hydrochemical analysis; the most important ions in wastewater are Cl-, Ca2, and Na, respectively. The concentration of these ions has unusually increased in samples taken from wells located near the wastewater site. Noting the stiff diagrams for several successive years, hydrochemical properties of these samples are the same as industrial wastewaters and the chemical anomalies created in the plain are resulted from wastewater recharge into groundwater resources. Furthermore, the main factors were determined that affect hydrochemistry of water resources in the study area using multivariate statistical analysis and Factor Analysis. Therefore, the most effective factor in hydrochemistry of the study area is the pollutant industrial wastewater that overshadowed the influence of geological formations and general sequence of groundwater hydrochemistry.
    Keywords: Factor analysis, Maragheh, Bonab plain aquifer, Multivariate statistical analysis, Water quality index
  • Vahid Rezaverdinejad Pages 123-136
    In this study, the performance of multi-layer perceptron (MLP), radial basis function (RBF) and generalize regression neural networks (GRNN), were evaluated to estimate cucumber, tomato and reference crops’ evapotranspiration (ET) in greenhouse environment. For this purpose, the lysimetric ET values along with the effective meteorological factors on evapotranspiration process, including air temperature, humidity, air vapor pressure, and incoming radiation were measured. The results indicated that introducing the all meteorological factors as artificial neural network models’ inputs increased the models accuracy. Based on the results, the GRNN model estimated the reference evapotranspiration with the highest accuracy in comparison to the RBF and MLP models. The average estimation errors of MLP, RBF and GRNN networks for the test phase were 9.4, 13.3 and 9 percent corresponding to the values of 0.24, 0.27 and 0.20 mm d-1, respectively. Performance of GRNN model in estimating cucumber and tomato evapotranspiration values also was appropriate. The average values of the errors for the estimated amounts of the cucumber and tomato evapotranspiration by the GRNN model, were 11.0 (0.21 mm d-1) and 10.1 (0.22 mm d-1) percent, while they were obtained by MLP and RBF models 11.4 (0.22 mm d-1) and 10.9 (0.26 mm d-1); and also 12.3 (0.23 mm d-1) and 13.8 (0.28 mm d-1) percent for MLP and RBF models, respectively. Based on ideal point error index, the GRNN model showed accurate performance in estimating crop evapotranspiration in greenhouse.
    Keywords: Air vapor pressure, Artificial neural network, Cucumber, Evapotranspiration, Incoming radiation, Tomato
  • Homayon Fagih Pages 137-152
    Accurate estimation of evapotranspiration (ET), which is one of the main components of hydrologic cycle, is very important in water resources management, irrigation planning and environmental studies. Accurate measurement of this component is very difficult, so the application of the models relying on available meteorological variables might be an alternative to direct measurement. This study aimed at evaluating multilayer perceptron artificial neural network as well as sixteen reference crop ET estimation models in Sanandaj. To achieve this object, lysimeteric ET values were considered as standard values for evaluating the applied models. The results showed that the FAO improved pan evaporation method provides more accurate results than other applied methods. In addition, the results indicated that the artificial neural network produces more accurate results for estimating reference evapotranspiration (ET0). Among others, the pan evaporation and artificial neural network models showed, respectively, 0.28% and 3.37% under-estimation and overestimation in the studied region.
    Keywords: Artificial neural network, Evapotranspiration, Lysimeter, Semi, arid climate
  • Azadeh Jamshidi*, Davoud Farsadizadeh, Ali Hoseinzadeh Dalir Pages 153-163
    Flow Separation in the upstream of the intake channel is a problem which produces an eddy flow at the intake entrance. It reduces the intake efficiency and the effective width of flow in intake and increases the sediment deposition in the intake entrance. Therefore, it is essential to identify the dimensions of the flow separation zone. Installation of submerged vanes in intake entrance is a method which has been applied to reduce the size of flow separation zone. In this research, the effects of submerged vanes on the dimensions of flow separation zone were investigated using five models of submerged vanes with different arrangement in four discharges of 15, 20, 25 and 30 Ls-1 in the main channel entrance. The Piney arrangement of submerged vanes was selected as the best model that reduced the size of flow separation zone and established a proper flow profile in the main channel and intake entrance. Comparing with the pilot model tests, this model reduced the length and width of flow separation zone 36.34% , 32.53% , 34.37% , 30.72% and 27.46% , 31% , 31.33 % ,30% at four different discharges of 15, 20, 25 and 30 Ls-1, respectively. Results showed that the ratio of width to length of separation zone (shape index of zone) was between two values 0.2 and 0.28 in the all models.
    Keywords: Flow separation zone, Intake channel, Shape index of zone, Submerged vanes
  • Mohammad Mehdi Heidari*, Samira Yousefi Pages 165-174
    Unsteady flow occurs in irrigation systems due to the water delivery operation and has direct effect on hydraulic performance. The most important characteristics of unsteady flow in open channels is the response time that is usually used to provide the irrigation schedule. There are some methods for numerical simulation of the unsteady flow in open channels, such as the Preissman four-point scheme. In this study, a computer model was developed to simulate the unsteady flow based on the Preissman scheme and verified with the observed data. The effects of the space step length, Δx, and time weighting coefficient, θ, on accuracy of the response time’s calculation were investigated using the numerical model. By increasing the computational reach length, the accuracy of the calculation of response time was reduced. Also suitable value of the weighting coefficient θ for simulation of the flow in irrigation network was estimated as 0.55. For determining the optimum computational reach length, 130 conditions of unsteady flow were simulated with numerical model, and the influences of Froude number, KF2, side slopes and the percentage of the inflow rate variations on optimum Δx were investigated. The results showed that KF2 and side slopes had a direct and Froude number had an inverse relationship with the optimum computational reach length, and the rate of sudden changes of discharge had no effect on optimum Δx. In this study, a nonlinear relationship for calculating Δx was presented with the Mean Percentage Error value of less than 4.3%.
    Keywords: Irrigation network, Optimum reach length, Preissman scheme, Response time, Unsteady flow
  • Marziye Abbaszadeh Afshar, Keivan Khalili*, Javad Behmanesh Pages 175-184
    One of the applicable methods for simulating and forecasting hydrological data is time series modeling approach. One of the main problems with applying time series modeling is generating stochastic series, since the generated data will be changed with changing the random series. In this research, after initial investigations on annual water level data of the Urmia lake, linear time series models were fitted to the data and the ARMA (3,0) model was selected as the best model among the ARMA series. Then, the time series residual of ARMA (3) model were fitted using non-linear ARCH (1) models, and a combined AR-ARCH model was obtained. The results showed that the combined model had more accuracy than ARMA (3,0) model. With combining the two mentioned models, values of the model validation accuracy (R2 coefficient) and error of model (Root mean square error) were improved 8.8% and 33%, respectively. Predicting results of Urmia lake water level showed that a climatic opportunity would be existed in the direction of Urmia Lake restoration.
    Keywords: Autoregressive, Conditional variance, Linear models, Nonlinear models, Time series
  • Javad Zahiri Pages 187-199
    In this study, bridge pier riprap sizing has been derived using new data mining techniques. Classification and regression tree (CART) and multivariate adaptive regression splines (MARS) were used to design a stable riprap size around bridge piers. The dimensionless parameters of pier shape factor (Ks), Froude number (Fr), pier width to flow depth ratio (b/y), specific gravity (1-Sg), riprap layers (n) and placement of riprap mattress to original sediment bed level (1-d/y) as input data and the riprap diameter to flow depth ratio (DR/y) as output one, were employed for training and testing the models. The applied models had similar performances in the training phase, while the results of testing phase showed better performance for the CART model. Some of the riprap stability equations and statistical criteria were used to investigate the performance of the applied models. The statistical analysis showed that the CART model had a better performance than the other equations, so that its sum of squares error value reduced to one-third, with respect to the Hec18 equation. In addition, the accuracy of the CART model was 88% which was 15% more than that of the Hec-18 equation. Sensitivity analysis on the CART model indicated that the Froude number and pier width to flow depth ratio had the highest effects on riprap stability.
    Keywords: Bridge pier, CART model, MARS model, Riprap, Sensitivity analysis
  • Alireza Nasimi*, Zargam Mohammadi Pages 201-215
    Hydrodynamic coefficients of aquifer are essential parameters in water resources studies such as water budget calculations and groundwater modeling. A small error in calculation of these coefficients causes large errors in water resources studies. The conventional methods such as Theis and Cooper - Jacob are generally used to estimate the hydrodynamic coefficients while theoretically, application of these methods produce considerable errors. In addition, wellbore storage and skin effect are usually ignored. In this research, pumping tests conducted in some of karst and alluvial aquifers in Fars Province were used. Although 52 pumping and observation wells were available only with respect to the completeness of the pumping test data, 20 pumping and observation wells were selected after checking accuracy of the data using diagnostic plots for evaluation of the methods for determining the aquifer hydrodynamic coefficients. In order to eliminate the error of wellbore storage and skin effect, the corresponding time interval was removed from the original drawdown-time data. This time intervals were identified using diagnostic plots. The results revealed that the errors of traditional analytical models in calculation of the hydraulic conductivity in the karst and unconfined alluvial aquifers were 88.22% and 76.09%, respectively. These models were only suitable for confined alluvial aquifers. Also wellbore storage and skin effect were identifiable in the large diameter pumping wells and in the other wells were ignorable.
    Keywords: Analytical model, Hydraulic conductivity, Skin effect, Transmissivity, Wellbore storage
  • Ebrahim Amiri*, Abdollah Bahrani, Afshin Khorsand, Mahta Haghjoo Pages 217-229
    This study was conducted for evaluating AquaCrop model performance in prediction of grain yield and biomass production of winter wheat, under water stress at Fars Agricultural Research Station (Zarghan), during two years (2006-2008). The experiment was a randomized block, based on a split plot design with four replications. Main plots consisted of two irrigation treatments, namely I1 (nonstressed), and I2 (Post anthesis water stressed plots with 65% FC). Each subplot consisted of three varieties; Shiraz, Marvdasht, and Chamran. Evaluation of the simulated yield and biomass production values were performed based on the measured data adjusted coefficient of correlation, relative error, and normalized root mean square error (NRMSE). Based on the results, the NRMSE values for the predicted grain yield of studied varieties in the calibration and validation stages were between of 0.5-2, and 2-9 percent, respectively. Also, the NRMSE values of calibration and validation in biomass production for the varieties, were between 2-5, and 3-6 percent, respectively. Results indicated that the AquaCrop model could predict the grain yield and biomass production with an acceptable accuracy.
    Keywords: Calibration, Model, Simulation, Validation, Winter wheat
  • Mehdi Karami Moghaddam*, Mahmoud Shafai Bajestan, Mahdi Nourzadeh Haddad Pages 243-255
    The main goal of hydraulic engineers is to design a water intake to deliver the maximum flow discharge with the minimum sediment entry. The optimum delivery angle, three dimensional flow pattern, sedimentation and sediment entry are the major parameters which must be considered at lateral intakes. According to the available literature, in previous studies the optimum water intake angle from main channel with slopping bank and suspended load had not been considered. Therefore, in this study, different sediment and hydraulic experimental tests were carried out at 30, 45, 60 and 90 degrees water intake installed at the bank of a trapezoidal channel. The effects of stream tube dimensions, secondary current and suspended sediment delivery into the intake were assessed for determining the optimum delivery angle. Finally, by analysis of these parameters, the 30 to 45 degrees angles were suggested to be the optimum delivery angles from a main channel with inclined bank.
    Keywords: Delivery flow, Intake, Optimum delivery angle, Stream tube dimensions, Suspended load entry
  • Ali Mohammad Khorshiddoust, Saied Jahanbakhsh Asl, Hamid Mir Hashemi*, Saeid Farzin Pages 257-270
    Evaporation from a water level is affected by non-meteorological and meteorological factors. In this regard the role of meteorological factors as determining elements is more than nonmeteorological ones. In this study, path analysis and partial correlation methods were used for the purpose of modeling and evaluating of the direct and indirect influences of the meteorological factors on the evaporation in the warm period of Tabriz city. After normalization of some data series of variables through Johnson functions, the potential evaporation Path model of the atmosphere was formed by use of the structural equation. The output of multiple correlations showed a significant 0.913 amount of the optimum model. The evaluation of the indices for the direct and indirect paths of the variables proportional to the evaporation indicated that temperature and pressure had the highest direct effects on evaporation respectively, while the vapor pressure saturation deficit showed the highest correlation with evaporation. Also in the most cases, a variable such as air pressure in a reverse path with its direct effect showed a correlation and this is the reason for the reduction of the correlation between this variable and evaporation. Generally, the results indicated that the application of structural equation and the differential correlation can model and discover the complicated and synthetic relationship of the meteorological variables in an acceptable extent.
    Keywords: Evaporation, Johnson functions, Normalization, Path analysis, Path coefficient
  • Somayyeh Ghasemi Pages 271-283
    Salinity stress and micronutrient deficiency are the most important factors limiting crop production in the calcareous soils in central area of Iran. One of the sustainable strategies to maintain the productivity and improve the fertility status of soil, particularly in arid and semi-arid regions with a soil having low input of organic material, is the use of organic and biological fertilizers with chemical types. In this study, the effect of different vermicompost levels including 0, 10 and 20 % (the weight ratio of vermicompost to the soil) on the nutrient uptake, growth and yield of tomato was investigated at three salinity levels, i.e. 0, 40 and 80 mM NaCl (electrical conductivity of 0, 3.65 and 7.30). The results showed that the salt stress caused significant reduction in root and shoot yield, but these negative effects of salt stress were significantly reduced by vermicompost application. The positive effect of the vermicompost on the plant growth was depended on the applied vermicompost levels. Salinity significantly increased the shoot Na concentration (375 %) and decreased the K concentration (23 %). The shoot Fe and Zn concentrations were also decreased by salinity from 338 and 31 mg kg-1 to 307 and 25 mg kg-1, respectively, while application of the vermicompost caused significant increase of these nutrients concentration in tomato. The effect of vermicompost on K:Na ratio was not significant while the salt stress caused significant reduction in this ratio. Based on these results, in addition to maintaining the nutrients balance in saline conditions, vermicompost could increase concentrations of Fe and Zn in plant and thereby reduced the stress-induced oxidative damage.
    Keywords: Calcareous soil, Iron, Salinity, Vermicompost, Zinc
  • Behjat Jabalbarezi, Mahdi Zarei*, Najafali Karimian, Mohammad Jamal Saharkhiz Pages 285-299
    Arbuscular mycorrhiza has positive impacts on the growth and yield of medicinal herbs under environmental stresses. In this study the effects of arbuscular mycorrhizal fungi on growth, nutrients uptake and essence oil content in savory plant (Satureja hortensis L.) under salt stress were evaluated in a greenhouse experiment. A completely randomized design in a factorial arrangement with two factors of arbuscular mycorrhizal fungi at three levels: non-mycorrhizal (NM) as control, Rhizophagus intraradices and Claroideoglomus etunicatum, and four levels of salinity (0.36, 2, 5 and 8 dSm-1 as NaCl) were performed in three replications. Salt stress decreased the shoot dry weight and plant height, root colonization, and the shoot nitrogen, phosphorus, potassium, calcium and magnesium uptake and it increased the root dry weight, shoot sodium uptake and essence oil content of the savory plant. Mycorrhizal plants had higher shoot and root dry weights, plant height and shoot nitrogen, phosphorus, potassium, calcium and magnesium uptake and the essence oil content in comparison with NM ones under salinity stress conditions. The highest content of essential oil was obtained in the plants inoculated with Rhizophagus intraradices at salinity level of 8 dS m-1.
    Keywords: Claroideoglomus etunicatum, Essence oil content, Nutrients, Rhizophagus intraradices, Salinity stress, Savory plant