Showing 33 results for Najafi
T. Najafi Mirak, A. Zali, A. Hossainzadeh, Gh. R. Rasoulian, A. Saeidi,
Volume 7, Issue 4 (winter 2004)
Abstract
Russian Wheat Aphid (RWA) is a serious pest of wheat, barely and other small grains in cereal-producing regions of the world. The use of resistant cultivars is an effective management strategy to control this pest. In this study, 15 lines and 13 cultivars of durum and bread wheats along with two resistant and susceptible controls were used to evaluate their reaction to RWA under greenhouse conditions, using completely randomized design with four replications. Three seedlings at each plot were considered as an experimental unit. Five aphid nymphs (4-5 ages) were placed on each plant at 1-2 leaf stage. Leaf rolling and leaf chlorosis percentages were measured 21 days after infesting and used to screen the genotypes. Despite the relatively high linear correlation between two resistance components, leaf rolling and leaf chlorosis, estimated as 80%, analysis of variance indicated significant differences among genotypes. Eight durum lines DW9, DW14, DW4, DW2, DW7, DW8, DW12 and DW3 and one bread wheat cultivar (Azadi) were significantly more resistant than the resistant control (Halt). One durum line (DW13) and two bread wheat cultivars (Shiroodi and M-75-7) had higher leaf rolling and leaf chlorosis than the susceptible control (Sholeh). So they were selected as the most susceptible to the biotype of D. noxia. under study. Orthogonal comparison showed that durum lines were more resistant than bread wheat cultivars. These results were confirmed by Cluster Analysis based on leaf rolling and leaf chlorosis.
M. Abdolahi Ezzatabadi, B. Najafi,
Volume 10, Issue 2 (summer 2006)
Abstract
In this study, at first, different models for measuring hedge ratios in futures and options markets were introduced. Then, the models were applied to a sample of 300 Iranian pistachio producers. The results showed that hedge ratios in pistachio futures and options markets, on average, were in a range of 0.22 to 0.99. When pistachio yield is unpredictable, options market is preferred to futures market. But in certain conditions, futures market is preferable. The results also showed that debt to asset ratio had a positive effect on hedge ratio, but bank loan effect was negative.
B. Najafi, M. Zibaei, M. H. Sheikhi, M. H. Tarazkar,
Volume 11, Issue 1 (spring 2007)
Abstract
In this study wholesale prices of selected crops, namely, tomato, onion and potatoes in Fars province were predicted for various time horizons by using common methods of forecasting and artificial neural networks (ANN). Monthly data from September 1998 to June 2005 period were obtained from Ministry of Jihad-e Agriculture. For comparing different methods data selected from September 1998 to December 2004 were utilized, and latest six - month data were mainly used to monitor the power of prediction. The MAE, MSE and MAPE criteria were used for comparing the ability of different forecasting methods. Results of this study showed that ANN had the lowest error in prediction of prices for one - to three - month periods, but for six - month prediction, all forecasting methods were not statistically different.
B. Najafi, A.r. Seifi, N.a. Babaeian Jelodar, A.m. Shakib,
Volume 12, Issue 43 (spring 2008)
Abstract
Sorrel (Rumex acetosa L.) is a model dioecious plant in genetic and molecular studies for sex determination. In this research, gus reporter gene transformation to leaf disks of this plant via Agrobacterium tumefaciens was evaluated based on transient expression of this gene. Three strains of Agrobacterium( LBA4404, C58 and EHA101) and two kinds of bacterial suspensions (suspension I: Agrobacterium cells were grown in LB medium with PH 7 and suspension II: the cells were resuspended in MS medium containing 100 mM acetosyringone with PH 5.2) were analyzed in a factorial experiment with 3 replications in Complete Randomized Design (CRD). Also, the effects of three different times of pre-culture of explants (0, 2 and 4 days) were examined. Results showed no significant difference among bacterial strains, whereas suspension I and explants without pre-culture had higher efficiency in gene transformation to this plant. Based on the best treatment, stable transformation with different days of cocultivation was carried out and revealed that the 4-day cocultivation is more efficient than the 2-day cocultivation in gene transformation to Sorrel. The histochemical GUS assay and PCR analysis were done on putative transgenic plants. Results showed that some of these plants contain at least one copy of the transferred gene or genes in comparison with control plants .
B. Najafi, A. Shirvanian, T. Haghshenas,
Volume 12, Issue 45 (fall 2008)
Abstract
In the process of agricultural development, sustainability of pasture utilization to ensure sustained production of meat and dairy products has become increasingly important. This article aims to study factors affecting pasture and meat production imbalances in Fars province. For this purpose, the transcendental production function was used. Data was collected by using two stage cluster random sampling from 71 producers. The results revealed that present method of pasture utilization is not compatible with increasing live animal meat production objective. To optimize pasture utilization, the pasture users should be advised to stop overgrazing. In addition, the results indicated that increasing livestock and pasture mismanagement causes damage to pastures and consequently would decrease meat production in the long-run.
F Hosseini, M Habibi Najafi, N Sedaghat,
Volume 13, Issue 48 (7-2009)
Abstract
In this study, two kinds of packages namely tinplate (TP) can and flexible pouch were used for black cherry in syrup. Samples were taken in the same condition in these two packages. Other variables were temperature (4 levels) 4, 23, 35 and 40°C and time (4 levels) 0, 30, 60 and 90 days after preparation of the samples. Samples were digested according to the approved method of AOAC (AOAC, 1990). The total concentrations of Iron, Tin and lead, were determined by atomic absorption spectrophotometer. The mean concentration of Iron, Tin and Lead was 4/858 ppm, 38/459 ppb, 38/459ppb in TP cans and 3/161 ppm, 387/978ppb, 33/993 ppb in flexible pouches. Statistical analysis showed that at %5 probability level, the mean value of Iron content of the product packed in TP cans were significantly higher than the control the same was true about both lead and Tin content. However, this trend was not proved in flexible pouches. Furthermore, temperature had a significant effect on the metal content of the samples.
N. Najafi, S. Mardomi, Sh. Oustan,
Volume 15, Issue 58 (winter 2012)
Abstract
The effects of waterlogging, sewage sludge and manure on the Fe, Mn, Zn, Cu, Pb and Cd uptake and concentrations in roots and shoots of sunflower (Helianthus annuus L.) were investigated in greenhouse conditions. A factorial experiment based on a completely randomized design with three replications including duration of waterlogging at five levels (0, 2, 4, 8, 22 days) and source and amount of organic fertilizer at five levels (0, 15 and 30 grams of both manure and sewage sludge per kg of soil) was conducted. The results showed that by increasing the duration of waterlogging, the Mn uptake and concentration in shoots and Mn concentration in roots increased but Mn uptake in roots did not change significantly. The uptake and concentration of Fe in shoots and Cd concentration in shoots and roots initially increased and then decreased after soil waterlogging, while Zn and Cu concentration of roots increased after an initial decrease. The effect of soil waterlogging on the Pb, Cu and Zn concentrations in shoots was not significant. By application of sewage sludge and manure the uptake and concentration of Fe, Mn, and Zn in shoots and Cu uptake in shoots increased but the uptake and concentration of Pb in shoots increased only by application of sewage sludge. The effect of source and amount of organic fertilizer on the Cd uptake and concentration in shoots, Cd concentration in roots and Cu concentration in shoots was not significant. By application of sewage sludge the root concentration of Fe, Mn, Cu and Zn increased but root concentration of Cd and Pb did not change significantly. The maximum uptake of heavy metals in shoots was obtained by application of 30 g sewage sludge/kg of soil. The effect of soil waterlogging on the heavy metals uptake and concentrations in the roots and shoots was dependent on the source and amount of organic fertilizer. Sunflower plant accumulated Fe, Mn, Zn, Cu, and Pb in roots while the Cd concentration in roots did not differ with shoots significantly.
M. Mardian, A. Najafinejad, J. Varvani, V. B. Sheikh1,
Volume 16, Issue 59 (spring 2012)
Abstract
Investigation in to the sediment delivery of watersheds and its variation is an important element of ecosystem management. Since sediment load depends on runoff quantity, and runoff is considered as a unique indicator of sediment load, in this research the two modified versions of the MUSLE model were evaluated for 9 torrential events in two subwatersheds of the Kamal Saleh watershed in the Markazi Province of Iran. To this end, first all factors of the model including runoff, erodibility, topographic, cover management, and support practice were estimated using routine equations of the model. Then, the power coefficient in the runoff factor was corrected, applying two methods: “m correction coefficient” and “average correction coefficient. The evaluation criteria showed that the “m correction coefficient method” (compared to the “average correction coefficient method”) reduces the difference of the observed and estimated sediment load of small and large torrential events remarkably. In fact, the application of this modified method increased the accuracy of the MUSLE by decreasing the standard deviation of prediction. Also, the validation analysis of the modified method showed that the coefficient of efficiency indexes for the Hasan-Abad station (Rudkhane Bozorg subwatershed) and Ghal'e-No station (Ashur-abad subwateshed) were 0.997 and 0.811, respectively. This result confirms the efficiency of application of “m correction coefficient method”. However, it is suggested that the performance of this method be evaluated using a sufficient number of individual hydrographs and their sedimentgraphs in other watersheds.
S. Ezzati , A. Najafi,
Volume 16, Issue 61 (fall 2012)
Abstract
Increase in soil bulk density and reduces in porosity and infiltration rate are the most common disturbances during timber harvesting and ground-base skidding. The present study was conducted to study soil physical properties e.g., soil bulk density, moisture, porosity and soil hydrological properties e.g., soil infiltration from ground-base skidding in twenty years since logging. After initial survey, four abandonment skid trails were selected with similar pedologic, climatic conditions and physiographic and different age in Necka-Zalemrod catchment in east of Mazandaran province. Results indicated that impacts of machinery traffices in high traffic intensity have remained yet 20 years since logging. Means soil bulk density, porosity and void ratio were 42.4 greater, 24.6 and 46.7 percent, respectively, lower than the undisturbed areas. The least infiltration rate was recorded in 1-5 years old skid trail, so the reduction of water was not considerable within 18 minutes after experiment into soil in inner ring in this skid trail. Results in each skid trail firmed that in low traffic intensity soil physical and hydrologic properties was tent to “normal” recover in compare to the undisturbed areas.
Mahnaz Zarea Khormizi, Ali Najafinejad, Nader Noura, Ataollah Kavian,
Volume 17, Issue 64 (summer 2013)
Abstract
Soil erosion is one of the most important factors affecting soil quantity and quality and is environmental problems in developing countries like Iran. It can have deteriorating effects on ecosystems. This research was carried out in farm lands of the Chehel-Chai watershed, Golestan province to investigate the effect of soil properties on runoff and soil loss. Runoff and soil loss were measured in a completely randomized design in 36 plots with 10×10 m sizes in farm lands. For this reason, this study was conducted using rainfall simulator with 2 mm/min intensity and 15 min duration in 4 replicates. Soil samples were also taken in each plot. Sampling was conducted in October 2009. Results of the Pearson correlation showed that among soil properties, the contents of the lime, silt and fine sand had positive correlations with runoff at 1% confidence level. Also, soil surface resistance at 1% confidence level, the contents of the organic matter and nitrogen at 5% confidence level had negative correlations with soil loss. Finally, the results of multiple linear models showed that the content of lime is effective in estimating runoff and soil surface resistance, and organic matter is effective in estimating soil loss.
S. M. J. Mirzaei, , S. H. Tabatabaei, M. Heidarpour, P. Najafi,
Volume 17, Issue 66 (winter 2014)
Abstract
There chemical and organic matter content in garbage leachate that may affect soil physical and hydraulic properties. The main objective of this study was to evaluate the influences of the leachate of Isfahan Organic Fertilizer Factory (IOFF) on some soil physical and hydraulic properties in a soil chemically enriched by Zeolite. The treatments include two soil textures (clay loam and sandy loam) and three levels of zeolite (0, 5 and 10 percent). The treatments were applied on lysimeters scale. The results showed that irrigation with the leachate caused a reduction of infiltration and hydraulic conductivity in the clay loam soil. The hydraulic conductivities in clay loam soil without zeolite (B0) before and after irrigation with leachate were 1.73 and 0.36 m/day, respectively. In contrast, there were no changes in the sandy loam soil’s infiltration and hydraulic conductivity. The hydraulic conductivities in the sandy loam soil with 5 percent zeolite (A5) before and after irrigation with leachate were 3.17 m/day. Furthermore, zeolite had a decreasing effect on those processes. The results show that irrigation with leachate caused reduction of bulk density in two types of soil and all levels of zeolite.
H. Akbari Mejdar, A. Bahremand, A. Najafinejad, V. Sheikh,
Volume 18, Issue 67 (Spring 2014)
Abstract
Over-parameterization is a well-known and often described problem in hydrological models, especially in distributed models. Therefore, using special methods to reduce the number of parameters via sensitivity analysis is important to achieve efficiency. This paper describes a sensitivity analysis strategy that graphically assigns for each parameter a relative sensitivity index and relationship of the parameter and the outputs of the model. The method is illustrated with an application of SWAT model in the Chehelchai catchment, Golestan province. In this study, total water yield, along with four major parts of water budget including surface runoff, lateral flow, groundwater and evapotranspiration was selected as objective function. SWAT is a river basin model that can be used to predict the impact of land management practices on water, sediment and agricultural chemical yield in watersheds. A relative sensitivity index was used for ranking the sensitivity of parameters. The results showed that soil evaporation compensation facto (ESCO), CN, soil available water capacity (SOL-AWC), deep aquifer percolation fraction (RCHRG-DP) and soil bulk density (SOL-BD) have the most influence on river flow. These parameters are generally stated as the most sensitive parameters of SWAT model in most of the same researches worldwide
N. Najafi, H. Towfighi,
Volume 18, Issue 67 (Spring 2014)
Abstract
Phosphorus behavior in waterlogged soils is significantly different from non-waterlogged soils. Changes in available phosphorus and inorganic phosphorus fractions after waterlogging in the paddy soils of north of Iran were studied in a laboratory research. A factorial experiment in a completely randomized design with two replications was performed with factors of soil at 14 levels (10 alkaline-calcareous and 4 non-calcareous or acid soils) and duration of waterlogging period at three levels (0, 30, 90 days). At the end of waterlogging period, phosphorus fractions in calcareous soils by Jiang and Gu method and in non-calcareous soils by Kuo method and available-P by Olsen method were determined. The results showed that the level of available-P in all soils was increased 90 days after waterlogging (on the average 2.3 times). In general, all P fractions were changed significantly after waterlogging and the amount of change was different depending on P fraction, soil type, and duration of waterlogging period. These results indicated the complex behavior of P in soils. The Al-phosphates were increased in 12 out of 14 calcareous and non-calcareous soils 90 days after waterlogging compared with air-dry soil. The Fe-phosphates were decreased in 9 out of 10 calcareous soils 90 days after waterlogging compared with air-dry soil while the effect of duration of waterlogging period on the Fe-phosphates in non-calcareous soils was not significant. The readily soluble-P in non-calcareous soils increased 30 and 90 days after waterlogging. The results indicated that some inorganic P fractions transformed into other fractions and probably organic P transformed into inorganic P during soil waterlogging period.
H. R. Owliaie, S. Heydarmah, E. Adhami, M. Najafi Ghiri,
Volume 18, Issue 68 (summer 2014)
Abstract
Rate of nonexchangeable K release can significantly influence K availability. Kinetics of K+ release was studied by extraction using 0.01 M CaCl2 in 12 surface calcareous soils of Kohgilouye Province. Results showed that cumulative K release ranged from 89.9 to 460.9 mg kg-1(Average 195.4 mg kg-1). Calcium carbonate, nonexchangeable K, cation exchange capacity and mica showed a significant correlation with K release. Maximum of potassium release was observed in Alfisols, probably because of high amount of clay content and the clay mineral of mica. The amount of K release was in the following order: Alfisols> Entisols> Inceptisols. Elovich, parabulic diffusion and power function equations could reasonably describe the K release kinetics. Fitting the data to these equations indicated that release of K is controlled by diffusion process.
M. Najafi-Ghiri, H. R. Owliaie,
Volume 18, Issue 69 (fall 2014)
Abstract
Although addition of amendment materials to soil is not for changing of soil K status, secondary effects of these materials can be important in K distribution among soluble, exchangeable and non-exchangeable forms. In this research, effect of addition of 2% zeolite, 2% vermicompost and 1% zeolite+ 1% vermicompost on 10 calcareous soils of Fars province belonging to five orders was investigated. The experiments were done as a randomized complete block with three replicates. Samples were incubated at 22±2 °C and 50% of saturated moisture content for 90 days. Then different forms of K were determined in the samples. Zeolite application induced 279 mg kg-1 increase in exchangeable K and 24 mg kg-1 decrease in non-exchangeable K, but it had not a significant effect on soluble K. Although vermicompost application increased soluble and exchangeable K, its effect was more sensible for soluble K (139 mg kg-1). Zeolite+vermicompost application increased all forms of K. Increase in soluble K with vermicompost application may increase risk of K leaching but zeolite application can preserve K in exchangeable phase and inhibit K leaching and fixation.
Sh. Moradipour, H. Zeinivand, A. Bahremand, A. Najafinejad,
Volume 18, Issue 69 (fall 2014)
Abstract
Evaluation of hydrologic behaviour and soil erosion as an environmental crisis is important in order to maintain watershed ecological safety at optimum level. The aim of this study is to evaluate the performance of the distributed hydrological WetSpa model in simulating erosion and sediment transport and also sedigraph in Taleghan watershed, Iran. Base digital maps and daily meteorological time series data for 9 years are the major model inputs. The calibration of global parameters was done for the first 5 years and the model validation was carried out for 4 years considering three month warm-up period at the beginning of both calibration and validation periods. The Nash-Sutcliffe criterion for the calibration and validation periods pointed out the efficiency of model simulation (82.7% and 79%, respectively). The next phase, the erosion module was calibrated for erosion and sediment transport simulation. The results showed the Nash-Sutcliffe efficiency criterion (60% and 64% for suspended sediment concentration and transport, respectively). Overall, the evaluation results reveal the good ability of WetSpa model in simulation of the hydrological processes e.g., runoff, raindrop detachment, runoff detachment, net soil loss, etc., in a given time and space
H. R. Owliaie, M. Najafi Ghiri,
Volume 18, Issue 70 (winter 2015)
Abstract
Topography and land use are among the most important factors affecting the soil formation. Chemical forms of Fe and magnetic susceptibility (χ) are widely used for the evaluation of soil development. This study was conducted in order to determine the effect of these factors on χ. A toposequence was selected in Madvan Plain, Northern Yasouj. Nine soil profiles (paddy and dryland soils) were dug and sampled from diagnostic horizons. Magnetic susceptibility was measured by Bartington Dual Frequency, MS2 Meter at frequencies of 0.46 and 4.6 KHz. Results indicated that less amounts of χ, frequency dependence of χ (χfd%) and CBD extractable Fe (Fed) (3.1, 2.6 and 2.7 times, respectively), and more quantities of oxalate extractable Fe (Feo) and Feo/Fed ratio (5 and 7.2 times, respectively) were measured in paddy soils. The highest value of χ was observed in pedons located on plateau and piedmont plains, and the lowest belonged to those located on river terraces with aquic conditions. Compared to paddy soils, χ enhancement at soil surface was greater (17%) in dryland soils. A positive correlation existed between χ and some soil characteristics such as Fed, clay content and χfd%.
M. Najafi-Ghiri, A. R. Mahmoodi, S. Askari,
Volume 19, Issue 72 (summer 2015)
Abstract
Potassium (K) is an important cation in saline soils of arid lands, and its content, distribution and availability may be affected by native plants. To study the effect of halophyte species on different K forms in Korsia region located in western Darab (Fars province), three dominant halophyte species including Juncus gerardi, Halocnemum strobilaceum, and Salsola rigida were selected. Sampling was done from soils in canopy and between plants at the depth of 0-15 (surface) and 15-30 cm (subsurface) in triplicate. Soil physical and chemical properties including soil texture, organic matter, calcium carbonate, pH, cation exchange capacity, saturation percentage and electrical conductivity and different K forms including soluble, exchangeable and non-exchangeable were determined. Results indicated that organic matter, CEC, pH, and EC were affected by plant species. Juncus gerardi increased exchangeable K and decreased soluble K, but it had no effect on non-exchangeable and HNO3-extractable K. Halocnemum strobilaceum significantly increased soluble, exchangeable and HNO3-extractable K in surface and subsurface soils rather than soils between plants. This finding may be due to K uptake by plants from subsoils and also transfer of soluble K from soils between plants to roots. Salsola rigida had no effect on K status. Generally, soils between plants had more soluble and exchangeable K in surface than subsurface horizon. The studied halophyte species showed differences in growth and development pattern, soluble salts and K absorption and secretion, grazing by livestock, returned organic matter to soil, soluble salts and K reserves in their organs, and water uptake and thereby water and K diffusion from soil far from rhizosphere to roots, which may have different effects on K distribution in soils. Juncus gerardi, as regards effects on decreasing salinity and soluble K and increasing exchangeable K, may be recommended as a suitable species for remediation of the studied soils.
M. Mokhtari, A. Najafi,
Volume 19, Issue 72 (summer 2015)
Abstract
Land use classification and mapping mostly use remotely sensed data. During the past decades, several advanced classification methods such as neural network and support vector machine (SVM) have been developed. In the present study, Landsat TM images with 30m spatial resolution were used to classify land uses through two classification methods including support vector machine and neural network. The results showed that SVM and neural network with the total accuracy of 90.67 % and 91.67% are superior. SVM had a better performance in separating classes with similar spectral profiles. In addition, SVM showed a better performance in delineating class borders in comparison with neural network method. In summary, both SVM and neural network showed satisfactory results but the method of support vector machine proved better with a difference of 1% and 2% in overall accuracy and kappa coefficient, respectively. This was an expected outcome because SVMs are designed to locate an optimal separating hyperplane, while ANNs may not be able to locate this separating hyperplane.
J. Saleh, N. Najafi, S. Oustan,
Volume 19, Issue 72 (summer 2015)
Abstract
The present study was conducted in order to investigate the effects of silicon and salinity on growth, chemical composition and physiological properties of rice var. Hashemi, in the greenhouse of agricultural college of University of Tabriz during 2011. It was arranged as factorial based on a completely randomized design with three factors consisting of silicon at four levels (control, 100, 200 and 300 mg/kg soil), salinity at four levels (control, 2, 4 and 8 dS/m) and source of salinity at two levels (NaCl and combination of different salts) with three replications. The results showed that increasing soil salinity resulted in a decrease in shoot dry weight, catalase activity and concentrations of phosphorus, potassium and reducing sugars, and an increase in glycine betaine content in the plants. The comparison between two sources of salinity also revealed that plants treated with a combination of salts experienced less vigorous decrease in dry weight and potassium, and reducing sugars' concentrations. Meanwhile, the enhancement in glycine betaine content appeared to be less intense in these plants. Hence, it could be concluded that the salinity resulting from a combination of different salts caused less damage to plants than NaCl salinity. Silicon supplementation resulted in increasing of shoot dry weight, catalase activity and concentrations of reducing sugars, glycine betaine, phosphorus and potassium. Therefore, silicon nutrition alleviated suppression effects resulting from the presence of soil salts, which means, enhanced the salt tolerance of rice.