Showing 69 results for Lar
E. Feyzian, M. Jalali Javaran, H. Dehghani, H. Zamyad,
Volume 11, Issue 41 (10-2007)
Abstract
Germplasm collection is the base of plant breeding. Iran is one of the most important centers of genetic diversity due to different climates and the old civilization.In this study we decided to collect melon accessions. The north and center of Iran were selected for this purpose. Fifteen qualitative and six quantitative traits were measured on thirty eight accessions. The cluster analysis by the use of UPGMA method and Jaccard coefficient helped separate the horticultural groups of Cucumis melo L. (Cantaloupensis, Inodorus, Flexousous, Reticulatus). The relationship between 30 of these accessions was assessed using 10 RAPD primers. The polymorphism was determined to be19%. The cluster analysis could not separate the horticultural groups of Cucumis melo L., showing that these groups are closely related. However, VB84 primer separated the tow Snakemelon.
E. Karimi, H. Rouhani, D. Zafari1, Gh. Khodakaramian, M. Taghinasab,
Volume 11, Issue 41 (10-2007)
Abstract
In order to study the biological control of carnation vascular wilt disease caused by Fusarium oxysporum f.sp. dianthi, 141 bacterial strains were isolated from carnation rhizosphere, and their antagonistic activity was evaluated against fungal pathogen in dual culture method. Among the tested strains, 16 strains showed antagonistic activity seven of them with more activity were selected for further investigation. Based on phenotypic features, strains E31 and E57 were identified as Bacillus cereus E76, E93, E102 and E121 as Bacillus subtilis and E130 as Pseudomonas fluorescens bv. III. All bacterial strains inhibited mycelial growth of F. o. f. sp. dianthi by production of non-volatile and volatile metabolites under laboratory condition. Microscopical analysis showed that all strains caused deformation of pathogen mycelium, and metabolites of these strains reduced conidia production rate and as well as the ability of conidia germination. In the in vivo tests, in sterilized and nonsterilized soils, the effect of bacterial strains was studied on disease severity, percentage of healthy plants and the growth rate of plants using soil inoculating and root-dipping into bacteria-methyl cellulose mixture methods. The E57 and E121 strains, in both methods, and E130 in root-dipping method showed highest effect on decreasing of disease severity and increasing of healthy plants percentage. Strains E57, E121 and E130 significantly increased total dry weight of carnation. Maximum dry weight was obtained by E57 and E130 in soil inoculating and root –dipping methods respectively.
E. Karimi, A. Lakzian, K. Khavazi, A. Asgharzadeh, G.h. Haghnia,
Volume 11, Issue 42 (1-2008)
Abstract
It is important to investigate the genetic diversity and evaluate symbiotic effectiveness of the indigenous rhizobial population. It helps understand the responses of indigenous isolates to different rhizobial inoculants. In spite of the importance of bacterial diversity, there are a few scientific reports about it in Iranian soils. Genetic diversity of 150 isolates of Sinorhizobium isolated from Hamadan soils was studied by using PCR / RFLP 16S-23S rDNA technique. The results showed that all isolates clustered in three different groups. Group (I) formed 122 isolates and they were quite similar to Sinorhizobium meliloti from viewpoint of genetic characteristics. Twenty five isolates were clustered in Group (II) and they belonged to Sinorhizobium medicae. Group (III) had two isolates and they were new species and quite different from the other groups. Shannon diversity index was different within eleven different land units (Medium gradient mountains, Level lands, Plateau, Foot slopes, Depressions and Composite land) and there was a correlation between Shannon index and some soil properties. Difference in Similarity index showed that Sinorhizobium groups in each land unit were different.
D. Safaee, S.m. Okhovat, G.h. Hedjaroude , H. Younesi,
Volume 12, Issue 43 (4-2008)
Abstract
In order to diagnose form species of Bipolaris involving root and crown rot of wheat plants and determine their distribution, frequency and disease severity, 410 wheat fields (W. Fs.) in different regions of Kermanshah province were sampled at seedling, tillering and heading stages during three crop years (1997– 2000). Also 90 W. Fs. (30 per year) in different regions of the province were chosen randomly to estimate percentage of infected wheat plants. For the isolation of the fungi from tissues of root, subcrown internodes, crown and foot, the tissues were surface sterilized and placed on culture media. The results showed that there were some root and crown rots in the most regions of the province and the percentage of diseased plants was 0-24%, whose average was 3.2%. Forty three isolates belonging to form genus Bipolaris were isolated including form species B. sorokinina, B. cynodontis and B. spicifera. All three form species were pathogenic under greenhouse conditions. Disease severity and frequency of B. sorokinina were more than the others. Disease severity of B. cynodontis and B. spicifera was the same and their differences compared with the control were significant.
M. Majzoobi, A. Farahnaki,
Volume 12, Issue 43 (4-2008)
Abstract
In this research the effects of two common cooking processes of foods, namely, autoclave and extrusion cooking on the molecular and physicochemical properties of wheat starch were investigated. The results showed that the solubility of the autoclaved samples increased with increasing the temperature while their relative viscosity decreased. These findings indicated that the molecular degradation of starch could occur during autoclave cooking. Moreover, constant sedimentation coefficient (s-value) of amylose and decreasing the s-value of amylopectin with increasing the temperature further confirmed degradation of amylopectin in particular. The results of the extruded samples showed that reduction in water content may increase the shear and pressure produced during extrusion cooking, which in turn could cause several changes in starch properties including degradation of starch granules, formation of amylose-lipid complex and degradation of amylopectin (as determined by reduction of the s-values). Also, reduction in water content could increase the puffiness of the final products and reduce the cold-water and final viscosities of the extruded samples. These observations may indicate the importance of the molecular studies of starch for better interpretation of physical changes of the final products.
M. Khosravi, R. Ebadi, H. Seyedoleslami, B. Hatami, Kh. Talebi Jahromi,
Volume 12, Issue 45 (10-2008)
Abstract
In this study diflubenzuron as a chitin synthesis inhibitor with a dosage of 25 mg A.I/L, and Pyriproxyfen as a juvenile hormone analogue with a dosage of 0.4 mgA.I/L were incorporated in the wax diets of young and last instar larvae of greater wax moth and reared at different temperatures (25, 30, 35°C). Results showed that these compounds in comparison with control increased larval mortality. Diflubenzuron and pyriproxyfen caused 33.9% and 24.1% mortality respectively. The young larvae showed higher mortality with the mean of 57.8% in diflubenzuron and 31.5% in pyriproxyfen. In evaluation of pupation and emergence of adults, no significant differences were observed between diflubenzuron and control. Pyriproxyfen induced reduction in pupation about 48.4% and adult emergence about 44.8% and caused some abnormalities of pupae. Last larval instar was more sensitive to JHA in this respect. Maximum pupation disruption occurred at 25ºC and 30ºC in comparison with 35ºC which reduced abnormal pupae up to 19.7%. IGRs were effective in last larval instar at 35 ºC and increased abnormality of adult up to 49.4%. Reproductive potential (egg viability, hatchability) of adults reduced in F1 generation and was 70-90 percent. IGRs have unfavorable effects on biological aspects of larvae therefore, it is possible to use IGRs alone or in conjunction with other pesticides (Fumigants) in integrated control of these pests.
A. Taghavi, Gh. Tahmasbi, A. A. Talebi, A. Zarnegar, A. Monfared, H. Nazarian,
Volume 12, Issue 45 (10-2008)
Abstract
The species diversity of bumblebees was investigated in two provinces, Tehran (Fasham, Zayegan) and Qazvin (Alamut, Wikan) in central Alborz during 2005-2006. Three casts of queen, worker and male bumblebees were collected during spring and summer in six dates in the two mentioned regions. Sampling of adult bees in Wikan was done from 26 July 2006 until 19 September 2006, and in Zayegan from 24 May 2006 to 17 September 2006. In sum, eleven species were collected of which eight species were common in the two regions. Data of different species casts at two regions were analyzed by Excel ver. 6 and Ecological Methodology ver. 6. 1. 2 soft wares. Species diversity of two regions was determined and compared with three indices of Simpson, Shannon-Weiner and Brillion, and evenness was calculated with indices of Simpson, Camargo and Esmit-Willson. Species richness of two regions was compared in research. The obtained results showed species diversity, evenness and species richness were more observable in Wikan compared with Zayegan. Consequently, Wikan in comparison with Zayegan was more sustainable. Similarity of two regions was 0/46, showing many differences in terms of the kinds. Also, there were 8 similar species in the two areas.
A Majnoni-Heris, Sh Zand-Parsa, A Sepaskhah, M.j Nazemosadat,
Volume 12, Issue 46 (1-2009)
Abstract
Global solar radiation (Rs) has wide applications in several disciplines. The data of measured or predicted Rs are widely applied by solar engineers, architects, agriculturists and hydrologists. Due to the importance of Rs, several empirical models have been developed to predict its values all over the world. In this study, Angstrom model was calibrated based on the ratio of actual and possible sunshine hours n/N by using measured daily data of Rs at Bajghah meteorological station in Fars province during 2003-2004. The model was modified by using air temperature for considering the effect of cloudy conditions as well as n/N ratios. The results showed that using both the air temperatures and the ratios of n/N led to a higher accuracy. In regard to estimation of the Rs values, the results showed that mean air temperatures have a higher accuracy compared with differences between maximum and minimum air temperatures. Also, a new local model with higher accuracy was developed based on a number of daily meteorological parameters such as deficit vapor pressure, relative humidity, precipitation, mean air temperature, maximum and minimum air temperatures difference and n/N. This new local model that used different meteorological parameters had the highest accuracy in comparison with the other models. Also, a number of models developed by other investigators for estimation of Rs were calibrated for the study area. Finally, different selected models were validated by using the measured data of Rs in 2005. The results showed that the developed local multi-variable model provided higher accuracy results in comparison with the other radiation models.
E Izadi, M Heidar Pour, A Kabiri Samani,
Volume 12, Issue 46 (1-2009)
Abstract
In this study, the flow characteristics have been investigated by measuring separation zone, surface and velocity profiles over the circular crested side weirs. An equation was proposed for the length of the separation zone using dimensional, statistical and regression analysis. The dimensional analysis showed that the length of separation zone depends on the upstream to the downstream water depth over the side weir, channel width to the downstream water depth and the Froude number. Comparison of the longitudinal and sectional surface profiles showed that the surface profiles at the vicinity of the side weir are non-uniform, due to separation zone close to the side weir. Therefore, the suitable place for measuring the characteristics of flow is along the centre line of the channel. It was observed that the maximum velocity occurred below the surface water which might be due to the secondary flow around the side weir. By increasing the distance far enough from the side weir, the effects of secondary flow were minimized and the velocity profiles tended to be uniform.
A Akbari, M Shahedi, N Hmadami, Sh Dokhani, M Sadeghi,
Volume 13, Issue 47 (4-2009)
Abstract
Sun drying is a well-known food preservation technique that reduces the moisture contents of agricultural products. Shrinkage, rehydration ability and color of food materials during air drying adversely affect the quality of the dried products. Since all fresh tomatoes can not be consumed at the time of harvest, preservation provides a larger market, allowing consumers to buy the preserved tomato through the year. A natural convection solar dryer consisting of a solar air heater and a drying chamber was manufactured in this research. Tomato slices were dried in the solar dryer and compared with open sun drying. Also, tomato slices were dried in a laboratory oven (operated at temperature 50, 60, 70, 80°C). With increasing the temperature, the time required to arrive certain moisture content is decreased. Also results showed that drying time in the solar dryer is shorter than open sun drying. In other words, drying time was reduced 17 to 45% by the solar drying in comparison to open – sun drying. The experimental shrinkage data showed a linear behavior with moisture content. Also, the experimental data didn't show a strong effect of temperature on the rehydration ability of the product. Thus, the effect of temperature and method of sun drying on the shrinkage phenomenon and the rehydration ability can be neglected. Tomato slices dried at 50°C had better appearance (lightness and red color) than at 80°C.
A Bahri, Gh Azari Takami, A Keyvan, Gh Vosoghi,
Volume 13, Issue 48 (7-2009)
Abstract
Immunostimulants are one of the important ways to prevent diseases. The vaccination and immune system stimulator and their combination can increase the ability of vaccines in prevention of diseases and improved indexes of growth and survival rates in shrimps. In this research, the separate and simultaneous effects of Ergosan and Vibromax vaccine on the growth factors such as total length and increasing of dry weight and survival rates in three stages of post larvae PL1,PL5 and PL15 in Indian white shrimp (Fenneropenaeus indicus ) were studied. The feeding of vaccine to shrimps was done through Artemia nauplii ( Artemia franciscana) enrichment. The effects of Ergosan (T1) and effect of Vibromax (T2) separately and in combination (T3) along with a control treatment for comparison were studied. Taking into consideration of 4 treatments and 3 replications for each of them, 12 similar vessels were used, which were refilled with 10 liters of water and reserved with 100 larvae in liters in zoa stages and were fed in a completely randomized design. Duration of experiment was from zoa stage to PL15 and in the end of 12, 16 and 25 days they were analyzed for the biometry and determination of survival rates. Results showed that the highest amount of total length (mm) was observed in PL1,PL5 and PL15 stages in T3 (5.26, 6.45 and 18.41) and was a little different from that in T1 (5.28, 6.32 and 17.94) which was significantly different from the control treatment ( 4.91 , 6.09 and 17.36 ) at P<0.05 level. Furthermore, T2 (5.11, 6.07 and 17.44) and control treatment were not significantly different (P>0.05). The highest amount of dry weight (mg) was observed in PL1, PL5 and PL15 stages in T3 (0.296, 0.890 and 2.940). In contrast to the control (0.216, 0.640 and 2.875) it was significantly different (P<0.05).The highest amount of survival rates (%) was observed in T3 (77.33, 76.33 and 80.67) which unlike control treatment (57, 57.33 and 59.67) was significantly different (P<0.05). The use of these two products in a desired feeding program from zoa stage to PL12 could increase the resistance and immunity in post larvae and survival rates and growth factors in shrimps leading to produce suitable post larvae for introducing into the training ponds.
M Moradi, A Zomorodian,
Volume 13, Issue 48 (7-2009)
Abstract
In this work, a cabinet solar dryer for thin layer drying of Cuminum cyminum was evaluated in two conditions (Indirect and Mixed). Four levels of drying air flow rates (three active and one passive) were adopted. The experiments were performed in a completely randomized Block design pattern in three replications. Drying durations were kept constant (90 min) for all the experiments. Average initial moisture content of Cuminum cyminum was 43.5 %( db) and the product was set to be dried for 90min in the solar dryer (average 8%d.b). The effects of the drying air flow rates and modes of drying were highly significant in final moisture content of Cuminum cyminum. Duncan test was selected to evaluate the effects of different factors on average moisture content of the samples. The results showed that the passive air flow system in mixed mode drying conditions for drying the Cuminum cyminum was best. The drying duration for the mentioned condition was 55min to dry the product from 43.5% to 8 %( db). The experiments were conducted each sunny day of August-September 2007 from 11.30 till 13.The average solar irradiance was recorded 750 W/m2 average ambient air temperature was32°C and average ambient relative humidity was20%. Using the dryer in the best selected conditions reduced the moisture content of the product from 43.5% to 4.95% after 90 min.
A Rahimi Khob, M Behbahani, M Jamshidi,
Volume 13, Issue 50 (1-2010)
Abstract
Daily solar radiation intercepted at the earth’s surface is an input required for water resources, environmental and agricultural studies. However, the measurement of this parameter can only be done in a few places. This has led researchers to develop a number of methods for estimating solar radiation based on frequently available meteorological records such as hours of sunshine or air temperature. In this study two empirical Angestrom and Hargreaves- Samani models, which are respectively based on air temperature and sunshine duration were calibrated and evaluated for estimating solar radiation in southeast of Tehran, Iran. Also, two neural networks models were presented using similar inputs and above-mentioned empirical models. The results showed that the both empirical and neural network models provided closer agreement with the measured values, but the models based on sunshine hours gave better estimates than the models based on air temperature. The neural network model based on sunshine hours with a R2 of 0.97 and a RMSE of 1.34 MJ m-2 d-1 provided the best results
H Asadi , H.r Moradi, A.r Telvari, S.h.r Sadeghi ,
Volume 14, Issue 53 (10-2010)
Abstract
The Clark method is one of the most applicable techniques for development of instantaneous unit hydrograph whose efficacy depends upon the accuracy in estimating storage coefficient. The present study was conducted in Kasilian watershed in Mazandaran Province to determine the efficiency of developed hydrograph using Clark's method and to compare the Muskingum storage coefficients obtained through graphical, Clark, Linsley, Mitchell, Johnstone-Cross and Eaton methods. To this aim, the time-area histogram of the study watershed was initially developed. The 3h-unit hydrograph was then derived using the data collected in Sangedeh climatological and Valikbon hydrometric stations. The efficiency of Clark’s instantaneous unit hydrograph developed based on 6 methods for calculation of Muskingum storage coefficient was ultimately compared with the observed average 3h-unit hydrograph of the study area. The results of the study revealed that the Clark’s instantaneous unit hydrograph obtained from graphical method for estimation of storage coefficient with estimation error of less than 33.33% and efficiency coefficient of 83% could suitably simulate different components of the observed average unit hydrograph for the study watershed.
H. Hamidifar , M.h. Omid , J. Farhoudi ,
Volume 14, Issue 54 (1-2011)
Abstract
This paper presents the results of an analytical and experimental study on the characteristics of hydraulic jump in a triangular channel. The analytical consideration is based on the momentum conservation law for the upstream and downstream sections of the jump. The experiments were carried out in a triangular channel of glass side walls with the vertex angle of 94.4°. A wide range of discharge and inflow Froude number were used in the experiments for two different opening heights of the upstream sluice gate. The main characteristics of the jump such as the sequent depth ratio, relative energy dissipation and water surface profile were investigated and the results were compared with those of the rectangular sections. The results showed that the triangular section is more efficient to dissipate the inflow energy. The efficiency of jump in a triangular channel is about 12% more than a rectangular channel for the same condition. As a result, hydraulic jump in a triangular channel needs a smaller tail water depth for a given inflow jet height and Froude number. Also, empirical relations and graphs are presented to determine the characteristics of the jump in triangular sections
A. Masjedi, M. Gholamzadeh Mahmoodi,
Volume 15, Issue 55 (4-2011)
Abstract
Every year river flooding causes serious damage to the bridges at the time needed most. One of the most effective factors causing bridge failure is scouring around the piers in a river bend. One of the methods to decrease scouring around the bridge piers is fitting them with a coller on the piers. The collars protect the river bed against vortex flow in the vicinity of the pier base. An experiment was conducted to study lab flumes made of Plaxiglass with a 180 degree bend and 2.8 m central radius and a 0.6 m width. In this study, a 6cm diameter pier was placed with a circular collar with four different collar sizes in one position in bend with constant discharge and depth under clear-water conditions. The collar was placed at four different elevations. The soil material had a diameter of d50 = 2mm and geometric standard deviation of σg = 1.3. The results of the model study indicated that the maximum depth scouring was highly dependent on the experimental duration. It was observed that as the size of a collar plate increases, the scour decreases. So, minimum depth of scour is dependent on the 3D coller and -0.1D elevation. Circular collar results in maximum reduction in scour depth (93%) compared with no circular collar.
M. Zarei, N. Saleh-Rastin, Gh. Savaghebi,
Volume 15, Issue 55 (4-2011)
Abstract
A greenhouse experiment was conducted in factorial experiment arranged as a completely randomized design (CRD) to evaluate the role of tree indigenous arbuscular mycorrhizal fungi (AMF) species originated from a polluted soil in phytoremediation of zinc polluted soils using maize as a host plant. The experiment consisted of plants inoculated with AMF (G1(Glomus intraradices), G2(Glomus mosseae) and G3(Glomus versiforme)) and G0 as non-inoculated plants and 5 levels of zinc (0, 10, 50, 100 and 500 mg kg -1) in non-sterilized sandy loam soil with three replications. According to the results of greenhouse experiment, the zinc and phosphorus uptake and also the biological yield of maize plants were significantly increased by inoculation with AMF in comparison with non-inoculated plants and also no zinc toxicity symptoms were observed. Uptake, translocation, and phytoextraction efficiency of plants inoculated with G. intraradices was more than the other treatments up to the level of 100 mg kg -1, but at the level of 50 mg kg -1 these amounts were highest in plants inoculated with G. mosseae. The efficicncy of three AMF in zinc uptake was highest at the low level of zinc. In general, under the high soil pollution (500 mg kg-1), G. mosseae was the most effective fungal species in Zn extraction and translocation while G. intraradices had the highest effectiveness for accumulation of Zn in the roots. The overall situation of G. versiforme was mostly between the two other fungal species.
A. Rahimikhoob, P. Saberi, S. M. Behbahani, M. H. Nazarifar,
Volume 15, Issue 56 (7-2011)
Abstract
In this study, the remote sensing statistical approach was used to determine the global solar radiation from NOAA-AVHRR satellite data in southeast of Tehran. This approach is based on the linear correlation between a satellite derived cloud index and the atmospheric transmission measured by the clearness index on the ground. A multiple linear regression model was also used to convert the five AVHRR data channels and extraterrestrial radiation to global solar radiation. The results of this study showed that multiple linear regression model estimated the solar radiation with an R2 of 0.93 and a root mean square error (RMSE) of 5.8 percent, which was better than the statistical approach.
P. Shojaei, D. Farsadizadeh , A. Hoseinzadeh Dalir,
Volume 15, Issue 57 (10-2011)
Abstract
Submerged vanes are low aspect ratio flow-training structures mounted vertically on the river bed at an angle to the prevailing flow. The aim of application of vane is to generate a secondary circulation in the main flow, designed to modify the near-bed flow pattern and thus redistribute flow and sediment transport within the channel cross section. Collar is a flat sheet with low thickness fixed vertically on the pier at stream bed level or near it. Installation of a collar leads to protect the river bed against the direct impact of downflow produced at the upstream face of the pier and therefore reduces the scour depth. This research is a laboratory study that examines the effectiveness of submerged vanes and combination of submerged vanes and collar as a pier scour protection device. Experiments were conducted in an 8 m long and 0.8 m wide flume and a cylindrical pier used was 6 cm in diameter. Clear-water scour tests with u*/u*c = 0.9 were performed with a collar 3 times wider than the pier diameter at the stream bed level and submerged vanes 1.5 times longer than the pier diameter at the stream bed level (H=0). Different arrays of vanes with different angles to main flow direction were employed. The highest reduction in the depth of scour hole with four vanes and a collar showed 61% reduction in scour depth.
Sh. Ghorbani Dashtaki, S. Dehghani Baniani, H. Khodaverdiloo, J. Mohammadi, B. Khalilmoghaddam,
Volume 16, Issue 60 (7-2012)
Abstract
Saturated hydraulic conductivity (Kfs) and macroscopic capillary length of soil pores are important hydraulic properties for water flow and solute transport modeling. Measuring these parameters is tedious, time consuming and expensive. One way is using indirect methods such as Pedotransfer functions (PTFs). The objective of this research was to develop some PTFs for estimating saturated hydraulic conductivity and inverse of macroscopic capillary length parameters (*). Therefore, the coefficients, Kfs and * from 60 points of Azadegan plain in Shahrekord were measured using single ring and multiple constant head method. Also, some of the readily available soil parameters from the two first pedogenic layers of the soils were obtained. Then, the desired PTFs were developed using stepwise multiple linear regression. The accuracy and reliability of the derived PTFs were evaluated using root mean square error (RMSE), mean error (ME), relative error (RE) and Pearson correlation coefficient (r). The highest correlation coefficients of 0.92 and 0.72 were found between Kfs-bulk density and *-bulk density, respectively. There was no significant correlation between soil particle size distribution and Kfs and *. This can be related to the fact that most of the soil samples were similar in texture and macro pores. The most efficient PTFs in predicting Kfs and * could explain 85 and 66 percent of the variability of these parameters, respectively. All the derived PTFs underestimated the Kfs and * parameters.
