Showing 107 results for Index
A. Rahimi Khoob, S.m.r Behbahani , M.h. Nazarifar,
Volume 11, Issue 42 (1-2008)
Abstract
Air temperature prediction models using satellite data are based on two variables of land surface temperature and vegetation cover index. These variables are obtained by atmospheric corrections in the values for the above data. Water vapor, ozone, and atmospheric aerosol optical depth are required for the atmospheric correction of visible bands. However, no measurements are available for these parameters in most locations of Iran. Using the common methods, land surface temperature can be measured accurately at 2 ° C. Given these limitations, efforts are made in this study to evaluate the accuracy of predicting maximum air temperature when uncorrected atmospheric data from the NOAA Satellite are used by a neural network. For this purpose, various neural network models were constructed from different combinations of data from 4 bands of NOAA satellite and 3 different geographical variables as inputs to the model in order to select the best model. The results showed that the best neural network was the one consisting of 6 neurons as the input layer (including 4 bands of NOAA satellite, day of the year, and altitude) and 19 neurons in the hidden layer. In this structure, about 91.4% of the results were found to be accurate at 3 ° C and the statistical criteria of R2, RMSE, and MBE were found to be 0.62, 1.7 ° C, and -0.01 ° C, 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.
H. Bayat, A.a. Mahbobi, M.a. Hajabbasi, M.r. Mosaddeghi,
Volume 11, Issue 42 (1-2008)
Abstract
Tillage is one of the important managing factors that can destroy or improve soil structure. Soil structure is affected by the machines and shape of the wheels. Field experiments were conducted at Hamadan Agricultural Research Station on a coarse loamy mixed mesic Calcixerolic Xerocrepts soil to measure and evaluate the effects of tillage and wheel-induced compaction on selected soil physical properties. Treatments included tillage methods (Moldboard Plow and Chisel Plow, (MP, CP)) performed using three customary tractors in Iran [John Deer (J), Romany (R) and Massey Ferguson ( MF) ]. Traffic zone and non traffic zone were other treatments. A split-plot design with three replications was used in a completely randomized arrangement of treatments. Soil samples were taken at the end of wheat growth season in traffic and non- traffic zone and from four layers and compared for bulk density (BD), cone index (CI), and mean weight diameter (MWD). The influence of both tillage methods on BD in most soil depths was not significant, meanwhile, BD was higher in the deeper layers. Wheel traffic did not affect BD significantly, but its effect decreased by increasing the depth. Commonly, conservation tillage increased structural stability as evaluated by MWD. Cone index illustrated the same trend as for BD, with some variation because of it higher sensitivity, so it was significantly was increased in CP rather than in MP for the traffic zone. Such a difference was not observed in non-traffic zone. The CI was also significantly increased in traffic zone compared with non-traffic zone. J significantly increased CI in two first layer in comparing with MF, but there was not significant difference between J and R. The MWD was increased by chisel plow in non-traffic zone and this increment was significant in fourth soil layer (22.5- 30 cm). Wheel traffic caused the increase of MWD in the second layer and significant difference was not observed in other layers. Overall, R caused less destruction in soil structure and tillage methods changed some of soil physical properties.
M. Naderi Khorasgani, A. Karimi,
Volume 11, Issue 42 (1-2008)
Abstract
This research was carried out to study the impacts of geomorphologic characteristics of claypan on land use and land degradation. Databank of the study area was constructed and digital terrain model of claypan was prepared. By using GIS techniques spatial distributions of the subsurface drainage network, sediment transportation index and wetness index were calculated. The results indicate that the depth to the claypan is between 0 (where the pan is exposed at the surface) to 605 cm. There are several depressions in the claypan which are filled by new sediments. Each depression has a catchment which is charged by the drainage water of its attributed lands. While a depression drains naturally or synthetically, the attributed soils over the depression are in non saline or moderate salinity condition otherwise, a marshland, a waterlogging area or a salt crust zone develops over there. The results also indicated that soil surface salinity is a function of depth to claypan and drainage condition of area. The trends of salinity extension are different for closed and open catchments and the depth to the claypan could be estimated using electrical conductivity. The results also show that analysis of microtopography of soil surface and soil stratification should be considered for designing irrigation and drainage networks.
O. Khademi, Y. Moustofi, Z. Zamani , M.r. Fatahi Moghaddam,
Volume 12, Issue 43 (4-2008)
Abstract
In this experiment the response of persimmon fruit, cv. Karaj, to astringency removal by ethanol and the effects of this treatment on some important fruit characteristics were investigated. Fruits were harvested at three different dates and at each date based on the previous results, and then modified treatments were applied. The best ethanol astringency removal treatment in this study was 10 ml of 38% ethanol per kg fruit for 48 hours. The period after ethanol treatments had no effect on the reduction of soluble tannin concentration, although it resulted in the reduction of flesh firmness and increased soluble pectin. Ethanol treatments and also temperature conditions reduced flesh firmness and increased ground color of fruits however, the effect of ethanol treatments was more than temperature conditions. Temperature conditions increased ethylene production, thus reducing the flesh firmness and increasing the ground color index of fruits. Ethanol treatments did not increase the ethylene production, and it seems that its effects on some characteristics are due to ethanol itself or factors other than ethylene.
E. Zare, A.h. Chizari, Gh.r Pykani,
Volume 12, Issue 43 (4-2008)
Abstract
Malmquist index computed by data envelopment analysis approach was used to estimate the total factor productivity (TFP) growth in cotton production in Iran during 1983-2001. By dividing this index in the two components, technological change and technical efficiency change, two major factors of productivity growth in cotton production were analyzed. Data was obtained from production cost system and other statistical sources provided by ministry of Jahad-e-Agriculture. Results indicated that TFP growth in cotton crop was positive (0.8% per annum) for the period of this study .This figure was different in different provinces of Iran. Maximum growth rate was 6.2% in Fars province and was negative in Kerman, Mazanderan and Golestan provinces. In comparison, technical efficiency growth was more than technological change during 1983-2001.
A.m. Amini, A. Zeynal Hamadani, M. Ramazani,
Volume 12, Issue 43 (4-2008)
Abstract
The general goal of this research was to study the most effective Intra-Organizational factors in the success of the poultry-farm cooperatives in Tehran province. To this end, viewpoints of 151 managers and members of agricultural cooperatives were collected and studied. Survey study was performed to evaluate the effects of four major parameters including member awareness of the principles and philosophy, training programs of members, participation in cooperatives' affairs, and expertise and ability of managers on the success index of poultry cooperatives. The results showed that the degree of members' share of training and knowledge of cooperatives' principles was very low also participation in cooperative's affairs and the managers' expertise and skills were medium. Using multivariate regression analysis, the above-mentioned four factors showed significant effects on the success of the poultry cooperatives with coefficients of 1.87, 0.46, 0.57 and 1.04, respectively.
E. Rahmani, A. Khalili, A. Liaghat,
Volume 12, Issue 44 (7-2008)
Abstract
The growing season climatic parameters, especially rainfall, play the main role to predict the yield production. Therefore, the main objective of this research was to find out some possible relations among meteorology parameters and drought indexes with the yield using classical statistical methods. To achieve the objective, ten meteorological parameters and twelve drought indexes were evaluated in terms of normality and their mutual influences. Then the correlation analysis between the barley yield and the climatic parameters and drought indexes was performed. The results of this study showed that among the drought indexes, Nguyen Index, Transeau Index, Rainfall Anomaly Index and Standardized Precipitation Index (SPI24) are more effective for prediction of barely yield. It was also found that the multivariate regression is better than the univariate regression models. Finally, all the obtained regression models were ranked based on statistical indexes(R,RMSE and MBE). This study showed that the multivariate regression model including wind speed, sunshine, temperature summation more than 10, precipitation and Nguyen index is the best model for prediction yield production in Miane. Average wind speed and Nguyen index were recognized to be the most effective parameters for yield production in the model.
B. Rayegani, S. J. Khajeddin, S. Soltani , S. Barati,
Volume 12, Issue 44 (7-2008)
Abstract
Snow is a huge water resource in most parts of the world. Snow water equivalent supplies 1/3 of the water requirement for farming and irrigation throughout the world. Water content estimation of a snow-cover or estimation of snowmelt runoff is necessary for Hydrologists. Several snowmelt-forecasting models have been suggested, most of which require continuous monitoring of snow-cover. Today monitoring snow-cover patches is done through satellites imagery and remote sensing methods. MODIS have smaller Spatial Resolution and more bands in comparison with Meteorology Satellite like NOAA. Therefore, in this research we used MODIS data for creating snow cover imagery. Existence of cloud in the study area is a major problem for snow cover monitoring. Therefore, in this research snow cover area changes were estimated without MODIS data period, but with DEM imagery and regressions between temperature, height and aspect. For this purpose, on 10 Esfand when the image was suitable we estimated the snow cover area. In comparison with real image, precision of the method was confirmed.
A. Moradi, A. Ahmadi , A. Hossein Zadeh,
Volume 12, Issue 45 (10-2008)
Abstract
Drought is a major factor limiting growth and development of crops such as mung bean (Vigna radiate (L.) wilczek) in arid and semi-arid regions of the world. This study was conducted to investigate the effects of different timing and severity of drought stress on physiological traits of mung bean and its relation to grain yield. A field experiment was carried out during 2004 growing season at Experimental Farm of Agriculture College, University of Tehran, Karaj, Iran. The treatments were laid out in a Randomized Complete Block Design (RCBD) with three replications. Plants were exposed to moderate and severe water stresses at either vegetative (VS) or reproductive stages (RS). Physiological traits were measured at the end of vegetative and the middle of pod formation. Generally water stress reduced leaf net photosynthesis rate, stomatal conductance and leaf relative water content at different growth stages. The effects of RS treatments were more severe than that of VS one. Severe VS treatment increased photosynthetic water use efficiency, whereas RS treatments decreased it significantly. However, leaf area index and total dry matter were more responsive in VS compared to RS treatments. VS treatments did not affect harvest index, while RS treatments reduced it significantly. Drought stress also reduced grain yield by 9 and 49 % (relative to control plants) in severe VS and severe RS treatments, respectively. Therefore irrigation is critical during reproductive stage mainly because of the higher demand for photoassimilate. It is concluded that to maximize mung bean grain yield in arid and semi-arid areas, appropriate watering should be practiced across all phenological stages in general, and during reproductive stage in particular.
H Miri,
Volume 12, Issue 46 (1-2009)
Abstract
In order to study changes in morphophysiological traits of wheat cultivars released from 1940 to 2000 in Iran and to determine the association of these traits with grain yield, an RCBD experiment was conducted with 15 wheat cultivars released during past 60 years in Arsanjan (Fars province) in 2006 and 2007. Results indicated that grain yield increased significantly during these 60 years (r=0.912, P<0.01). HI and BY increased significantly with increasing grain yield. The changes in photosynthesis rate were not significant during this period, but transpiration rate and stomotal conductance in recent cultivars increased significantly. Chlorophyll index also increased in new cultivars. Among yield components, grain number per ear increased significantly, but increase in ear number was not significant. Plant height decreased significantly in new cultivars. The results showed that during wheat breeding in Iran, increasing HI, grain number per ear, transpiration rate, stomatal conductance and decreasing plant height had the highest role in wheat yield increase. The role of BY and ear number per area were lower in grain yield increase. It seems that present HI values are near the highest possible value, but the opportunity for increasing grain yield by mean of HI is still possible.
M Naseri, M Rezai, M Abasi, S Jam, H Hosseini, O Sabzevari,
Volume 12, Issue 46 (1-2009)
Abstract
Common kilka were chilled during 1, 2, 3, 4 and 5 days to determine the influence of such storage times of fish over the quality of the final canned product. For this propose, common factors for determination of fish quality (moisture, total lipid, free fatty acid, peroxide, thiobarbituric acid and fatty acid profile) were selected and compared with the formation of fluorescence compounds in fish tissue and filling media of canned kilka. In this work common indices showed higher oxidative and hydrolytic rancidity of canned samples compared to raw material but the trend of deterioration with the increase of chilled storage time was not well shown. However, filling media fluorescence compounds was significantly increased with the increase of chilled storage time and the decrease of fish primary quality (P< 0.05). According to the present results, fluorescence detection of interaction compounds can provide a good technique to assess quality differences in the final product as its relates to the quality of the raw material used.
Gh Dehghani, F Malek Shhi, B Alizadeh,
Volume 13, Issue 48 (7-2009)
Abstract
Canola (Brassica napus L.) as one of the oilseed crops has recently received lots of attention due to its suitable oil quality and high oil percentage. To evaluate the effect of water deficit stress on canola genotypes with regard to yield, drought tolerance quantitative indices and identify drought tolerant genotypes, an experiment was conducted in research farm of seed and plant improvement Institute (Karaj) using completely randomized block design with four replications, and 25 genotypes under two stress and non stress conditions. Genotypes were evaluated regarding drought tolerance. Drought tolerance quantitative indices include MP, GMP, STI, SSI and TOL. Result of variance analysis showed significant differences among genotypes as regards all indices and seed yield of genotypes in both conditions at 1% probability level. MP, GMP and STI indices were selected as the best indices for selection of tolerant genotypes in regard to analysis of correlation between seed yield in two stress and non stress conditions and drought tolerance indices. Results indicated that Genotype Vectra was the best genotype, because of its proper mean yield in both stress and non stress conditions. Multivariate biplot figure display showed that MP, GMP and STI indices had high correlation coefficient with each other, and tolerant genotypes were located near tolerance indices. Also results of three dimensional scatter plot and cluster analysis indicated that genotypes Modena, Jura, Eshydromel, Vectra, Dante, Zarfam, Esbetty and Olano were tolerant to drought stress, and genotypes Olpop, GKHelena, RG4504 and Olphi were sensitive genotypes.
A Sh, S J,
Volume 13, Issue 48 (7-2009)
Abstract
In selection index procedure, phenotype and genetic (co)variance matrices of traits are used for calculating different genetic parameters like index coefficients, index variance, genetic gain in selection goal and selection accuracy. Sometimes, it is possible that these matrices become inconsistent or they are not positive, nor definite. In the current study, for investigation of the effect of inconsistency of (co)variance matrices on the results of selection index procedure, 6 kinds of different selection indices: milk production (Milk) , fat percentage of milk (fat%) and herd life (HL) in selection goal were constructed The first to third indices included Milk, fat% and one of the type traits, i.e. rear udder height (Ruh), front teat placement (Ftp) or front udder attachment (Fua) respectively, as correlated traits with herd life. The fourth index included productive traits and the three mentioned type traits altogether, and the fifth and sixth indices as reduced indices, included milk production and fat percentage and just milk production, respectively. Also, the results of using mean of 3 individual records were taken into account. All of calculations were done for both consistent and inconsistent matrices. For making consistency in inconsistent matrices, “bending” method was used. Results showed that the use of inconsistent matrices in selection index calculations will lead to wrong selections and will decrease genetic gain. This conclusion was independent of different economic conditions of production system in different years. When using consistent matrices, index 4, that had the most information from selection goal, was the best index.
F Ahmadloo, M Tabari, A Rahmani, H Yosefzadeh,
Volume 13, Issue 48 (7-2009)
Abstract
This research was carried out to improve the growth and performance of Arizona cypress (Cupressus arizonica) and Medite cypress (C. sempervirens var. horizantalis) seedlings in different combinations of organic matter in nursery of Koloudeh, located in Amol city (north of Iran). Seeds in plastic pots were sown as a completely randomized design (RCD) with four replications at different soil treatments including: T1) nursery soil (control), T2) control soil: cattle manure (5:1), T3) control soil: decomposited litter (5:1), T4) control soil: cattle manure: decomposited litter (5:1:1). The results after one year showed that the seedlings of both species grown on T4 obtained the greatest shoot height, collar diameter, seedling Vigor Index, shoot dry weight, root dry weight, total dry weight and seedling Quality Index (QI) among all the soils examined. The response of most attributes to soil was better in Cupressus arizonica than in C. sempervirens. It is concluded that organic matter caused the increase of growth and biomass of seedlings in both species. It can be proposed that in order to enhance the performance and improvement of Quality Index of seedlings in nurseries, the status of physico-chemical of soil-media should be seriously evaluated.
A Shaabani, A Kamgar Haghighi, A Spaskhah, Y Emami, T Honar,
Volume 13, Issue 49 (10-2009)
Abstract
Oil seed rape (Brasica napus) is an important crop, which is cultivated in Iran for oil production. As a management practice deficit irrigation strategy is applied to cope with water shortages, especially during drought periods. This research was conducted to study the effect of water stress on physiological parameter of oil seed rape in the experimental research field of Collage of Agriculture (of shiraz university) during 2004- 2005 and 2005- 2006. Licord cultivar of oil seed rape was planted and experimental design was random block with five treatments and four replications. Treatments were full irrigation in all growth stages, water stress in vegetative stage in early spring, water stress in flowering and podding stages, water stress in grain filling stage and dry land treatment with supplemental irrigation in time of planting. Water stress caused decrease in water potential of plant, an increase in canopy temperature, and decrease in plant height especially in dry land treatment. Leaf area index decreased as water stress increased. The decrease in leaf area index was more severe in vegetative stage water stress treatment. At the end of water stress period leaf area index increased again. Rate of decrease in leaf area index at the end of the growing season was higher in grain filling stage of water stress treatment.
M. Boyerahmadi, F. Raiesi , J. Mohammadi,
Volume 14, Issue 51 (4-2010)
Abstract
Similar to plants, soil salinity may reduce microbial growth and activities in different ways. The aim of this study was to determine the effects of different levels of salinity on some microbial indices in the presence and absence of plant's living roots. In this study, five levels of salinity using NaCl, CaCl2, MgCl2 and KCl and three soil media (soil with no plant, soil cultivated with wheat and clover) replicated three times consisted our factorial experiment arranged in a completely randomized design. Results show that salinity caused a significant reduction in accumulated microbial respiration, microbial biomass carbon, substrate-induced respiration, and carbon availability index in uncultivated soil and in the soils planted with clover and wheat. Results also show that salinity caused a significant increase in metabolic quotient (qCO2) in uncultivated soil, and soils planted with clover and wheat. Microbial activity of cultivated soils at high salinity levels was almost similar to that of the uncultivated soils. We observed a small difference in soil microbial activity among the three media at high salinity levels, indicating the role of indirect effects of salinity might be less important with increasing salinity levels. We also found out that at low salinity levels, the available carbon was not a limiting factor for soil microflora, while at high salinity levels the activity of soil microbes might be carbon-limited. The lower values of qCO2 in cultivated soils compared with the uncultivated soil support the positive influence of root and its exudates on soil microbial activity in saline soils. The existence of plants in saline environments may help in alleviating the detrimental influence of low to medium salinity on most soil microbial activities, likely via the added root exudates and root turnover.
L. Parviz , M. Kholghi, Kh. Valizadeh,
Volume 15, Issue 56 (7-2011)
Abstract
The determination of air temperature is important in the energy balance calculation, hydrology and meteorological studies. In this regard, the limited number of meteorological stations is one of the serious problems for air temperature determination on a large spatial scale. The remote sensing technique by covering large areas and using updated satellite images might be appropriate for estimation of this parameter. In this research, the negative correlation between land surface temperature and vegetation index (NDVI) has been used for air temperature estimation through TVX method in which the inference of air temperature is based on the hypothesis that the temperature of the dense vegetation canopy is close to air temperature. For investigation the performance of TVX method, images of MODIS sensor have been applied for the Sefidrod River basin in the years 1381- 1382-1384. The spilt window technique which was developed by Price has been used for land surface temperature calculation. The mean difference between observed and estimated land surface temperature using Price algorithm was about 6.2Co. This error can affect the air temperature values. Because of using NDVI index in TVX method, this method has the sensitivity to the vegetation density, though in the parts with sparse vegetation, the value of error increases. 4 percent variation of air temperature against the 0.05 increasing of maximum NDVI indicates the high performance of TVX method for air temperature estimation in large areas.
A. Safadoust , A. Mahboubi, M. R. Mosaddeghi, Gh. Khodakaramian, A. Heydari,
Volume 15, Issue 57 (10-2011)
Abstract
In this study, the transport of nalidixic acid-resistant Escherichia coli (E. coli NAR) through two soils of sandy loam and clay loam was investigated. Saturated and unsaturated flow conditions were applied at two temperatures of 5 and 20ºC. Leaching was done using large repaired soil columns which had been subjected to physical weathering. A 20-cm diameter disk infiltrometer was set up to establish the steady-state flow conditions. Effluent was sampled at three depths of 15, 30 and 45 cm of soil columns. Saturated flow condition, temperature of 20 ºC and clay loam soil resulted in increasing the bacteria concentration in the leachate. Filtration coefficient and relative adsorption indices in sandy loam soil (average flow conditions, temperature and depth) were greater than those of clay loam soil with the respective values of 33% and 23%. These results may be related to the instability of soil structure and abundance of micropores in the sandy loam columns. In other words, the bacteria were physically blocked and entrapped in the fine pores of sandy loam soil. Effluent bacteria concentration decreased by depth of soil column, indicating the effect of soil on bacterial filtration as a natural filter. Leaching with cold water led to decrement of flow rate and consequently increment of bacterial filtration in the two soils of clay loam and sandy loam (average flow conditions, temperature and depth) with the respective values of 100% and 68%.
M. Teimouri, M.r. Ghanbarpour, M. Bashirgonbad, M. Zolfaghari, S. Kazemikia,
Volume 15, Issue 57 (10-2011)
Abstract
Baseflow separation has long been an important topic in hydrology and has a crucial role in water resources management in arid and semi arid regions like Iran. In this paper, a comparison among commonly used automated techniques for hydrograph separation including theoretical method of local minimum and digital filter of one parameter with different filtering parameters of 0.9 to 0.975 and two parameter methods was done to estimate baseflow using baseflow index. For this purpose, daily flow data in some stream gauging stations in west Azarbaijan province were used. For comparison, in addition to baseflow index the graphical method based on the observed daily flow data and correlation coefficient among them was utilized. The main aim of this research is distinguishing the most suitable method in hydrograph separation and estimating the baseflow. Results showed that in different methods baseflow largely contributes to streamflow and also has high fluctuations. However, the results of the digital filter with two parameters appear to be hydrologically more plausible than those of the other methods, but the results of digital filter with proper parameter - in this region one parameter method with filter of 0.925- has proper estimation accuracy. Also, the baseflow index based on method of two parameter digital filtering varies from 0.54 to 0.78 in this study area.
