Showing 8 results for ahmadzadeh
Z. Ahmadzadeh, B. Hatami,
Volume 7, Issue 3 (fall 2003)
Abstract
Greenhouse whitefly, Trialeurodes vaporariorum West. is one of the most important pests of the field crops and ornamental plants in greenhouses. Pest control is based on using chemical insecticides and biological control agents. In this study, the efficiency of the green lacewing, Chrysoperla carnea ( Steph.) with release ratios of 1:1, 1:5, 1:10, 1:15, and 1:20 (predator:prey) using eggs in chrysobag and the effect of three insecticides including Confidor (35% Sc), Permethrin (25% Ec) and Dimilin (25% Wp) at concentrations of 0.3 ml/l, 0.3 ml/l and 0.15 g/l in water, respectively, were investigated. In one experiment, the eggs of the green lacewing were released on tomato plants that were infested with 150 different nymphal instars of the pest. Control treatment included chrysobag whithout any egg. After 11 days, nymphal mortality was calculated. In insecticidal experiments, in control treatment, only water was sprayed. Both experiments were conducted in a randomized complete block design with four replications in a greenhouse with 25±5 °C, 50-60% RH and 14:10 LD period light conditions. The means of data were compared using Duncan Multiple Range Test. The results showed that the maximum nymphal mortality of 52.42% was due to the release ratio of 1:1 (predator:prey) however, this was not sufficient and did not control the pest population. The results of the chemical control also revealed that one application of Confidor caused the highest mortality about 88% that was more effective in reducing pest population compared with the release of predator eggs. Neither method had absolute control. In general, results indicated that to be more effective the two methods need to be applied more than once, and they must be combined into one or with other control methods.
Z. Ahmadzadeh, B. Hatami,
Volume 9, Issue 4 (winter 2006)
Abstract
Greenhouse whitefly, Trialeurodes vaporariorum West., is one of the most important pests of field crops and ornamental plants in greenhouses which usually controlled by chemical insecticide and/or by biologic control factors. In this study the effect of singular and integrated use of Confidor and predator, Chrysoperla carnea (Steph.) against different nymphal instars of the pest on tomato plant was investigated. This experiment was carried out in 7 treatments, each in 3 replicates. Treatments included predator alone, the use of insecticide alone, and 4 integrated treatments of both the predator and insecticide. The predator was released at 5, 10, 15 and 20 day intervals after insecticide application. The control (water), insecticide spray and release of the predator were repeated each 10 days. In integrated treatments, insecticide was applied only once at the beginning of the experiment. The results showed that there was a significant difference between treatments. Pest control was not achieved with one or two attempts of release of predator or spray of insecticide. Pest elimination was only observed after third spray in insecticide treatment and 3 releases of predator beginning 20 days after spray in integrated treatment. These two treatments were shown to be of equal effectiveness in pest control. Also pest population was controlled after 5 releases which began 5 days after insecticide application. The use of the alone predator was statistically found to be less effective than treatment with the insecticide alone. Generally, integrated treatment is a promising alternative approach to pest control in longterm. It has clear advantages over chemical control in terms of pest resistance, environmental and general pest control issues. .
Sh.a. Sarani, A. Sharifi Tehrani, M. Ahmadzadeh, M. Javan Nikkhah,
Volume 11, Issue 42 (winter 2008)
Abstract
Two hundred fifty seven bacterial isolates were collected from colza root and rhizosphere in Golestan, Mazandaran, Guilan and Tehran provinces. Antagonistic effect of bacterial isolates on Rhizoctonia solani, the causal agent of colza damping off, was studied using dual culture method. The results showed that, 60 isolates had the ability to inhibit the growth of R. solani on PDA medium. On the basis of the biochemical, physiological and morphological tests, isolates P1, P2 and P3 were identified as Pseudomonas fluorescens. Biocontrol mechanism studies showed that isolates produced antibiotics and volatile metabolites prevented the mycelial growth of the fungus. The isolates produced some of antimicrobial metabolites including hydrogen cyanide, protease and siderophore. Isolate P3 was more effective to inhibit the growth of the fungus in-vitro. The effect of isolates on disease reduction in comparison with control was significantly different. None of the isolates were able to prevent disease occurrence completely. Isolates applied as soil treatment had a significantly higher disease control as compared to seed treatment method. Isolate P3 had considerable effect on reduction disease in the greenhouse conditions. All isolates were capable of colonizing canola roots and so increased canola growth in free-causal agent conditions.
A Karimi, M Noshadi, M Ahmadzadeh,
Volume 12, Issue 46 (1-2009)
Abstract
In this research the effect of Super Absorbent Polymer (SAP) on the crop growth, wilting point, sunflower survival, water holding capacity, and irrigation interval was investigated. The experiment was conducted with different concentrations of absorbent hydrogel (Igeta): 0% (control treatment), 0.05%, 0.1%, 0.2%, and 0.3% (w/w). The soil textures were sand, loam, and clay. The experiment was a completely randomized design with three replications. The results of this research are: 1- Adding of Igeta to the soil changed solid, liquid, and gas phases. Application of 0.05%, 0.1%, 0.2%, and 0.3% (w/w) of Igeta increased the volume of clay, loam and sand soils between 10-40% , 5-32% and 9-37%, respectively. 2- With application of Igeta, absorption of nutrients (N, P, and K) was increased. Maximum absorption nutrients occurred at the level of 0.05%, 0.1%, and 0.3% with confidence level of 90% for clay, loam, and sandy soils, respectively. 3- Igeta increased water holding capacity and irrigation intervals. Increasing in irrigation interval was between 30-130% in clay, 60-120% in loam, and 150-300% in sandy soils. Water saving in clay, loam, and sandy soils was 30%, 40%, and 70%, respectively. 4- at the level of 0.3% Igeta, starting time of temporary wilting point was delayed from 4 to 10 days (150%) in clay and loam soils, and from 4 to 12 days (200%) in sandy soil. The starting time of permanent wilting point was delayed from 8 to 12 days (50%) in clay, 7 to 12 days (71.4%) in loam, and 9 to 14 (55.5%) days in sandy soils. Therefore, application of Igeta delayed starting time of permanent wilting point between 50-71% and temporary wilting point between 150-200%.
H. Ahmadzadeh, A. Fakheri Fard, M.a Ghorbani, M. Tajrishy,
Volume 25, Issue 3 (Fall 2021)
Abstract
In drought risk management, the regional analysis of drought is significant. In this paper, this important issue is investigated by presenting the new hydrological regional drought index (RDI). For this purpose, the Ajichai basin was selected as the study area. First, the time series of the streamflow drought index (SDI) was calculated for each of the hydrometric stations in the basin f regional analysis of hydrological drought. Then, to determine the homogeneous regions in terms of hydrological drought, the k-means method was used for clustering analysis. Based on the clustering results, 6 Homogeneous regions were identified in the basin. For each of these regions, the time series of the RDI index was calculated from 1365 to 1393. The results showed that during the study period in each of the regions 1, 2, 3, 4, 5, and 6, mild Wet and mild drought has occurred at 82.1, 80.1, 78.9, 83.3, and 84.3 percent of regions, respectively. Also, the total percentage of drought events (moderate and high) is higher than the total percentage of wet events (moderate and high) in all regions. So, during the study period, the total percentage of drought events (moderate and high) is more than twice the total percentage of wet events (moderate and high) in regions 2 and 3.
H. Ahmadzadeh, A. Fakheri Fard, Mohammad Ali Ghorbani, M. Tajrishy,
Volume 26, Issue 3 (Fall 2022)
Abstract
Determining the actual evapotranspiration value and analyzing its temporal trend is essential for optimal water resources management in a basin. In the present paper, the actual evapotranspiration time series is simulated and its trend is analyzed according to the trend of climatic variables and land use in the Ajichi basin during the period of 2015-1987. The comprehensive SWAT model was set up, calibrated, and validated for the Ajichi basin. Also, the average of simulated actual evapotranspiration of crops (in wet years) was compared with similar values in the National Water Document. The results of the Mann-Kendall trend test showed that the annual rainfall in most meteorological stations had a decreasing trend and the rainfall trend in the ten stations decreased significantly. While the annual maximum temperature at all stations and the annual minimum temperature in most of them have significantly increased. Investigation of land use maps illustrated that the irrigated land area of the basin has increased by a 39% during the study period. According the study's results, the potential evapotranspiration of the basin has had a significant increasing trend with a rate of 2.54 mm per year. The results indicated that despite the increasing trend of potential evapotranspiration and irrigated land area, the actual evapotranspiration of the basin had a significant decreasing trend with a rate of 2.2 mm per year due to the decrease in rainfall.
F. Naeimi Hoshmand, F. Ahmadzadeh Kaleybar,
Volume 26, Issue 3 (Fall 2022)
Abstract
Hydrological models for evaluating and predicting the amount of available water in basins, flood frequency analysis, and developing strategies to deal with destructive floods are expanding daily. In this study, HEC-GeoHMS and Arc Hydro extensions in ArcGIS software and the HEC-HMS model were used to simulate design flood hydrographs in the Aydooghmush basin in the northwest of Iran. SCS-CN, SCS-UH, Maskingham, and monthly fixed methods were used to calculate rainfall losses, rainfall-runoff transformation, flood routing, and base flow, respectively. In model calibration with two real flood events, the average of absolute values of the residuals, the sum of the remaining squares, and the weight of the peak mean the error squares for the flood volume were 2.75, 5.91, and 5.32, respectively and for peak discharge were 8.9, 8.0, and 8.0, respectively. Model validation was evaluated as acceptable with a one percent error rate in the peak of discharge and a 19 percent in the flood volume. For maximum 24-hour precipitation, the log-Pearson type 3 was determined as the most suitable distribution in the SMADA model and design precipitation was extracted in different return periods. Thus, for the return period of 2 to 1000 years, the peak discharge and volume of the design flood were simulated equally to 18.8 to 415.6 m3 s-1 and 5.7 to 87.9 MCM, respectively.
F. Ahmadzadeh Kaleibar, M. Fuladipanah,
Volume 27, Issue 2 (Summer 2023)
Abstract
Using transfer functions to predict soil moisture parameters has been considered strictly a scientific and economical method among researchers. In this research, field capacity (FC) and permanent wilting point (PWP) of soil were predicted using classic regression (linear and non-linear), support vector machine (SVM) algorithm, and gene programming expression (GEP) algorithm based on three performance assessment criteria as determination of coefficient (R2), root mean square error (RMSE), and standardized developed discrepancy Ratio (DDR) in the Arasbaran plain in the northwest of Iran. Independent parameters were determined as clay percent (Cl), silt percent (Si), gravel percent (Sa), organic carbon (OC), bulk density (ρb), and actual density (ρs) which (S, ρb, ρs) and (ρb, ρs) were opted to predict FC and PWP using Gamma test, respectively. The results showed that each three transfer functions are capable to simulate FC and PWP parameters but the SVM algorithm is the superior predictor among the three functions so the values of (R2, RMSE, and DDRmax) of training and testing phases for FC were obtained (0.9908, 0.5517, 17.50), (0.9785, 0.7004, 11.62) and those of PWP were calculated (0.9782, 0.5764, 2.85) and (0.8389, 1.187, 3.09), respectively.
