Journal of Water and Soil Science
Year:2008 | Volume:12 | Issue:44|Papers Count:37

Estimating the volume of groundwater contribution to runoff within a watershed is one of the most important subjects in water resources management and hydrology. In this paper, groundwater contribution to total runoff as a base flow index was estimated using hydrograph separation in six stream gauging stations in southwest of Iran. The major objective of this research is to distinguish the most suitable automated hydrograph separation and base flow estimation method. Conventional automated hydrograph separation methods including local minimum and recursive digital filter with the parameter of 0.9 to 0.975 were compared with recession analysis numerically and graphically. The results showed that recursive digital filter with the parameter of 0.925 are the most accurate method to estimate base flow in the studied watersheds. This research also indicated that the base flow index estimated through the selected method varies from 0.79 to 0.88 in the study area.

Total petroleum hydrocarbon (TPH) contaminations in soils may be toxic to human, plants and cause groundwater contamination. To achieve maximum TpH- reduction and to establish successfull stable vegetation cover in phytoremediation method, various criteria must be considered to choose the plants carefully. In this study, germination and subsequent growth of seven plants were tested in three soils with different petroleum contamination levels. Contamination treatments consisted of C0 (uncontaminated soil), C1 (1:1 w/w, uncontaminated: contaminated soil) and C2 (1:3 w/w, uncontaminated: contaminated soil). The experimental design was completely randomized split plots with three replications per treatment. The results showed that the presence of TPH in the soil had no effect on seed germination of agropyron, white clover, sunflower and safflower although canola seedlings were sensitive to these compounds and failed to produce dry matter yield (DMY) at the end of trial period. In contrast, seed germina ion of canola, puccenillia and tall fescue decreased in the petroleum contaminated soils. No reduction was found in DMY of puccenillia in contaminated soils (C1 and C2 treatments) compared to control; however, the presence of TPH proportional to the contamination levels, decreased dry weight of sunflower and safflower. This reduction in growth anddry weight for tall fescue and agropyron was also observed in C2 compared to C1 treatment. Therefore, it seems that though agropyron, white clover, sunflower and safflower germinated well and the presence of TPHs in the soil treatments had no effect on their seed germination, they grew poorly. In contrast, grasses had poor seed germination but their subsequent growth and establishment in the contaminated soils was acceptable for subsequent phytoremediation trials.

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, and 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.

In tea plantation regions of northern part of the country, application of supplemental irrigation during dry periods (lacking rainfalls) in conjuction with proper nitrogen fertilizer application can significantly improve tea yield per unit of plantation area. In order to quantify the effectiveness of proper irrigation and nitrogen management on tea, the response of tea to various levels of irrigation and nitrogen applications was studied in Fouman suburb of Guilan province. Tea crop production function and its crop coefficient (KC) were determined. A line source sprinkler irrigation was used for creatiating a variable irrigation application and a split-split-plot statistical design was used. Irrigation treatments consisted of full irrigation (I4), deficit irrigation (I3, I2 and I1) and no irrigation (I0). Nitrogen application treatments were N1, N2 and N3 (100, 180 and 360 kg/ha) in three replications randomly arranged as main plots, while irrigation treatments as sub plots were not randomized. During the growing period, soil moisture up to the depth of 90 cm was determined gravimetrically and actual crop water use was calculated from mass balance equation weekly. Reference evapotranspiration (ETo) was estimated by Penman-Montieth equation and was used to estimate tea crop coefficient. During growing period, the actual tea water use of I4 and I0 were computed to be 457 and 256 mm. Tea crop coefficient during dry period (June, July and Augest) ranged from 0.8 to 0.9. Crop resistance factor (Ky) for tea was found to be 1.37. Results indicated that optimum rate of nitrogen (180 kg/ha) along with supplemental irrigation, increased yield and water use efficiency (WUE). Futhermore, supplemental irrigation increased yield and WUE more than nitrogen application. In I0 and I1 treatments, application of 100 kg/ha nitrogen resulted the highest yield and WUE.

Limitations of rainfall and surface water resources farmers have to use both surface and subsurface resources for growing different crops. In this study optimal management of irrigation water allocation and cropping pattern utilizing conjunctive use of surface and subsurface water resources is studied. Also the effect of reducing water c onsumption in different growth stages with different irrigation strategies for major crops (wheat, barely, corn, sugar beet, rice) in Fars province was studied. The results of the study showed that optimal cropping pattern for the first season would be mainly wheat and in the second season would be corn and rice. Also in this model different policies for decreasing water demand were studied. Since crop water requirement in the second season is higher than the first season, therefore restriction on including high water consuming crops in the second season would be the best choice in the cropping pattern.

Root depth is one of the main parameters affecting soil moisture availability held within the plant root zone. This study was conducted to evaluate the trend of corn root development during the growing season in different irrigation methods with two water qualities, and distribution of roots in soil profile. The experiment was a split plot design with three main treatments (subsurface drip(SSD), surface drip(SD) and furrow irrigation(FI)) and two sub main treatments (municipal  effluent and fresh water) in two consecutive years conducted in Korbal plain, Fars province. Root monitoring was carried out with the observation of soil profile root depth measurement. Samples were taken during the growing season 16 times, each with a 7 day interval. Measurement of root weight in different soil layers was carried out using monoliths of soil washed with water pressure using 50 mesh sieves. Although the longest roots were observed in plots irrigated with SSD and the shortest in FI, the final root length was not significantly affected by irrigation methods and water qualities. In this research, a model showing the trend of root length average growth was developed and tested in the experiment conditions. The average final main root depth for all treatments was 77 cm. Irrigation volume using root depth monitoring could be reduced compared to linear model, Borg & Grimes and CROPWAT model for root depth estimation. Irrigation water on the base of soil moisture deficit within the root zone in each irrigation event could be reduced when the real root depth is considered compared with the conventional general models giving a final root depth. Results showed the total dry root weight in SSD was more than that in SD and FI methods. However, water quality did not show a significant effect on dry root weight. The most root concentration in SSD was measured in depth of 20-40 cm, while in SD and FI the most concentration was in surface layer (0-20 cm). In the SSD, the roots were distributed more evenly compared with SD and FI methods. The concentration of roots in all treatments below 65 cm was not significant.

For an appropriate drip irrigation system design, a prediction of soil wetting pattern is needed for a given soil texture. The wetting pattern geometry is a key factor for emitter distance determination as well as crop type. The geometry of the wetting bulb is dependent on the parameters such as soil hydraulic properties, emitter discharge and the irrigation time. This study has been conducted in Albaji region in km 25 on the Ahvaz-Andimeshk road, in order to estimate the geometry of the wetting pattern under the point source trickle emitters in sandy soil with different discharge. The emitters were calibrated to provide 5, 10, 20, 30 and 40 liter per hour discharges. The maximum wetted soil surface and depth was measured by digging the irrigated soil. Two models were developed to predict wetted soil surface diameter and depth under a point source based on Buckingham's p theorem. The equations were calibrated by using the measured data. Then resulted scientific-empirical equations have been evaluated. Considering the maximum relative error of 14.3% and root mean square error of 3.8cm in estimation of the wetted soil surface diameter and depth, the models are recommended to estimate the geometry of the wetting bulbs with a high degree of accuracy, and can be used in designing and appropriate drip irrigation system management.

Transport and filtering of pathogenic bacteria through porous media and groundwater resources are important and' therefore the effect of various factors on bacteria transport and filtering has been given a great attention nowadays. In this study' effects of calcium sulfate and carbonate on Psedomonas fluorescens filtration and filtering parameters were investigated in saturated sand columns under steady-state flow. The calcium carbonate levels included 0' 5' 10 and 20 %w/w and calcium sulfate levels consisted of 0' 5 and 10 % w/w which were thoroughly mixed with sand (015-0.25 mm). The experiment was considered factorial in completely randomized design with three replicates. The treated sands were poured into pyrex cylinders with length of 20 cm and diameter of 7 cm. Then' steady-state saturated flow with constant flux was applied to the columns. When the steady-state flow was established' the bacteria suspension with concentration of 106 CFU cm-3 (C0) was injected as step input into the columns. The leaching then was continued up to 5 times of pore volume (PV). The effluent concentration of the bacteria (C) was measured at 0.25 PV intervals. Then' the sand columns were divided into 0-5' 5-10' 10-15 and 15-20 cm layers in order to measure the filtered bacteria in each layer. The results showed that the effects of calcium carbonate on retaining of the bacteria in the 5-10 and 10-15 cm layers were significant at 1% level. It was significant at 5% for the 15-20 cm layer. The effect of calcium sulfate was also significant at 5% for the 10-15 cm and 15-20 cm layers. The interactive effects of treatments on bacteria adsorption was significant for the 5-10' 10-15 and 15-20 cm layers. The retained concentration profile and the filtration coefficient were significantly affected by the treatments' showing higher bacteria adsorption at lower depths and predominance of physical filtering. The results showed the high filtering capacity of carbonate and sulfate minerals which could ultimately reduce bacteria transport in saturated porous media towards groundwater resources.

Canola (Brassica napus L.) in response to salinity represents various resistances with respect to its phonologic stages. Most plants such as Canola are resistant at germination stage. However, at seedling or earlier growth stages, plants become more sensitive to salinity but their tolerance increases with age. Salt tolerance of various plants has been extensively studied; however, the results have either been qualitative or expressed as average values over root zone salinity for the whole growth season. Thus, developing appropriate models for quantitative characterization of plant response to salinity at different growth stages is essential. Canola which is considered as high economic value plant was selected for this study. Two productive stages for canola are recognized as flowering and ripening. To determine the effect of salinity on canola at vegetative growth stages, a greenhouse experiment was conducted on a natural saline loamy sand soil, using salinity treatment including one non-saline water (tap water) and 8 saline waters of 3 to 17 dS.m-1. The canola plants were irrigated with tap water before the desired stage and then salinity treatments were imposed. The Maas and Hoffman (1977), van Genuchten and Hoffman (1984), Dirksen et al., (1993), and Homaee et al., (2002b) models were used to predict relative transpiration ( Ta /Tp ) and relative yield (Y/Ym ) as a function of soil salinity. The maximum error (ME), root mean square error (RMSE), coefficient of determination (CD), modeling efficiency (EF) and coefficient of residual mass (CRM) statistics were calculated to compare the models and their efficiencies. The results indicated that the van Genuchten and Hoffman (1984) model provides best prediction at flowering stage. However the Homaee et al. (2002b) model offers better prediction at ripening growth stage.

Soil physical and chemical properties, and test conditions might affect soil structural stability. In this study, the effects of test conditions as well as intrinsic soil properties on structural stability were investigated for selected soils from Hamedan Province. Mean weight diameter (MWD) and tensile strength (Y) of aggregates were determined by wet sieving method and indirect Brazilian test, respectively. The soil samples were pre-wetted slowly to matric suction of 200 kPa before the wet sieving. The pre-wetted samples were wet-sieved for 5, 10 and 15 min in order to simulate different hydro-mechanical stresses imposed on soil structure. Tensile strength of soil aggregates were also measured at air-dry and 500 kPa matric suction conditions. Short duration shaking (i.e. 5 min) could effectively discriminate the Hamedan soils in terms of structural stability due to their fairly low aggregate stabilities. The soil organic matter content had the highest impact on MWD followed by both clay and CaCO3 content. The same was true for the Y values i.e. OM played the highest role in mechanical strength of soil aggregates. The highest coefficient of determination (R2) was obtained between Y and the intrinsic soil properties for matric suction of 500 kPa. The organic matter content had an important role in water and mechanically stable soil aggregates. The results indicated that short-duration wet sieving (i.e. 5 min) and measurements of tensile strength at matric suction of 500 kPa could be recommended for aggregate stability assessment in Hamedan soils.

Determination of landscape evolution is useful to well understand the physical environment and it also enables us to conduct the soil related studies. The objective of this study was to establish the historic evolution of Zayandeh-rud Valley from late Tertiary to Quaternary. To achieve this objective, the spatial structure of a representative area of Zayandeh-rud Valley in three dimensions was examined. Responsible geologic and geomorphic processes of landscape formation were determined and inherited records and evidences of changes in soil development were investigated. The inherited foot marks and different analyses proved that following the Zayandeh-rud River formation, from Miocene to present time, the following processes and events have occurred during valley formation pathway: 1- formation of old gypsiferous gravelly alluviums, 2- lagoon formation, the change in the river pathway, 3- playa formation, 4- river terrace deposition and 5- starting of wind erosion.

Mineralogy is one of the most influential soil properties that change from upper- to lower slope positions, depending on the climate differences. Such changes affect soil properties such as phosphorus sorption and desorption processes differently. Therefore, this study was carried out to investigate the clay mineralogy of soils in four toposequences from arid (Isfahan) and semiarid (Chaharmahal Bakhtiari) regions and its effect on soil P release. The soils of three points on each toposequence were sampled as the upper-slope mainly containing parent materials; the mid-slope, non-arable lands; and the lower-slope, arable lands. Some of soil properties such as clay minerals were determined. Also, trend of P release parameters was studied in four toposequences. Results showed that the amount of clay, cation e xchange capacity (CEC), electrical conductivity (EC), and pH of the soils increase down the slope in all toposequences. X-ray diffractograms showed that kaolinite and illite in upper slope and smectite and chlorite in lower slope were the predominant clays. Among the kinetic models examined based on their determination coefficient and standard error, the Elovich equation was chosen to describe the P release kinetics in studied soils. The trend of P desorption rate along the arid toposequences was in the following order: upper-slope < mid-slope < lower-slope. Furthermore, the rate of P desorption in soils of the semiarid toposequences was higher than arid toposequences. Regarding the trend of P rate parameters along the toposequences, it could be concluded that P release rate and the soil capacity to supply P for plants increase toward lower slope.

Nitrogen (N) is usually low in the majority of agricultural and non agricultural soils in Iran, mainly due to the lack of adequate soil organic matter (OM). On the other hand, boron (B) toxicity is becoming more widespread in arid and semi arid regions of this country, where soils or irrigation waters contain relatively high B content. Results of the research indicate that addition of certain plant nutrients such as N may reduce the harmful effect of high B levels. Therefore, the present experiment was undertaken to evaluate the interactive effect of N and B on the growth and chemical composition of rice in a calcareous soil. Treatments consisted of six B rates ( 0, 2.5, 5, 10, 20 and 40 mg kg-1 as boric acid) and four levels of N ( 0, 75, 150 and 300 mg kg-1 as urea) arranged in a factorial manner in a completely randomized design with three replicates. Application of B decreased shoot dry matter. At low B levels, N application alleviated the toxic effect of B. Moreover, the addition of B increased B and N concentrations in the rice shoot. The N concentration increased and B accumulation decreased with increasing N rates. There was a general trend of increase in shoot N and chlorophyll concentrations with increasing chlorophyll meter reading. Chlorophyll concentration decreased with increasing B levels. N fertilization increased chlorophyll content and somewhat reduced the adverse effects of high B rates on this plant parameter. The results reported herein show that in soils with high B levels, N application may alleviate the suppressing effects of B toxicity and increase rice growth possibly due to a decrease in B absorption by the plant.

Despite the existence of highly silty soils in southern Mashhad, there is no information about the aeolian and /or in situ formation of these soils. The main objective of this study was to determine the source of silt generation in this area. Granitic hilly lands in southern Mashhad have been covered by silty deposits. Based on the soil origin, four profiles including a residual soil covered by a silty layer, a residual soil with low amount of silt, a highly silty soil and an alluvial soil as well as a deep profile containing a succession of silty and alluvial materials were studied. Cumulative particle size distribution curve (CPSDC), depth distribution curves of silt/sand ratio (Si/S), Folk inclusive graphic standard deviation, Folk inclusive graphic skewness (SKI) and sand grain morphology analyzed by scanning electron microscopy (SEM) were determined and used to identify the source of the silty materials. Based on the results obtained, silty (L), residual-silty (R-L), residual (R), alluvial (A) and alluvial-silty (A-L) horizons were identified. CPSDC of L horizons is sigmoidal in shape and is easily distinguishable from that of the other horizons. In contrast, the CPSDC of alluvial and residual horizons is spherical in shape. CPSDCs for R-L and A-L horizons are neither sigmoidal nor spherical, but something in between. The L horizons have the highest SKI (very skewed to fine particles) and the lowest Folk inclusive graphic standard deviation (very badly sorted). In this regard, alluvial and residual horizons are intermediate. Because of the silt addition to R-L and A-Lhorizons, these horizons have a nearly zero SKI (symmetrical) and the highest Folk inclusive graphic standard deviation (very badly sorted). Particle size distribution histograms of RL and A-L horizons are bimodal, a mode for sand and a mode for silt, suggesting two different sources. Depth distribution of Si/S, SKI and Folk inclusive graphic standard deviation of highly silty and other horizonz show a drastic change between L horizons and the other horizons-an indication of lithologic discontinuity and difference in origin. In conclusion, despite the possible contribution of granitic parent rocks to silt generation in the area, loess deposits recognized appear to have mostly been transported by aeolian movement.

In the conventional methods of herbicide and fertilizer application, a substantial amount of toxic chemicals is sprayed or broadcast into the furrows, which is later washed away by irrigation water and may contaminate ground water, human and animal environment. If herbicide and fertilizer application could be limited to the most needed parts of the field rather than overall broadcasting, the mentioned problems could be alleviated and the application efficiency could also be increased by reducing the consumption rate. In an attempt to achieve this goal, a combination cultivator capable of simultaneously performing cultivation practices such as weed control (mechanical + chemical), fertilizer application and pest control was developed and evaluated. This machine was able to perform band spraying (fungicide, insecticide and herbicide) and mechanical cultivation (within-the-row weed killing, furrow reforming and hilling) simultaneously and properly. The combination cultivator was able to reduce herbicide consumption up to 66%.

Occupational safety and health of agricultural workers have not yet received their due attention in developing countries. This is particularly true in the case of tractor drivers who operate tractors in unfavorable conditions and in a high level of seat and tractor vibrations. Therefore, an investigation of vibration sources and finding the methods for decreasing them are of considerable importance. In this research, vibrations that the tractor operators of different weights are exposed to while operating any of the three commonly used tractors in Iran during plowing with moldboard plows, disk harrows or routine road travel at two forward speeds were examined. Acceleration data of tractor body and its driver, while riding the tractor, were measured and recorded. Later, Fast Fourier Analysis, and root mean square of weighted accelerations for the cases of driver health and comfort were analyzed and evaluated. Results revealed that the level of forward speed did not have any significant effect on vibrations introduced to drivers body, however, the average of acceleration vectors on different tractors and their drivers’ bodies revealed a significant influence (P<0.01). Moreover, with increasing a driver’s mass, the average of acceleration vectors on his body decreased. For example, a driver of 55 kg mass, bore a maximum acceleration vector of 9.8 m/sec2, while a driver with 100 kg mass, had a minimum acceleration vector of 3.3 m/sec2. In a comparison of permissible riding hours/day, JD3140 and U651 tractors recorded maximum and minimum, respectively. Also acceleration vectors for different tractor operators compared with international standards showed that the comfort level for these tractors was extremely low.

A considerable portion of threshing losses and waste of rice takes place in threshing stage. One of the effective factors in threshing losses and waste of threshing units, threshers and harvesting machines, is the drum speed. In this research, effects of three factors including drum speed (five levels), crop moisture content (two levels) and rice common varieties (four varieties) on threshing losses and waste were studied. The thresher T25 was used for the investigation. It has wire loop type tooth. Dependent factors included unthreshed grains percentage (threshing losses) and damaged grains percentage. The obtained data was analyzed by split–split plot test based on Complete Randomized Blocks Design. The mean values were compared using Duncan’s Multiple Range Test. The tests results revealed that significant effect of variety type and drum linear speed on threshing losses (P<0.01). Furthermore, the effects of variety type, moisture content and drum speed on damaged grains were also significant. The optimum drum speed was 14 m/s. The most and the least of threshing losses belong to Hashemy and Binam varieties, respectively. Among the tested varieties, Binam variety showed the highest percentage of the damaged grains. In general, decreasing the crop moisture resulted in increasing the mean damaged grain.

Due to yield increase, some farmers in Iran plant sugarbeet in 50-cm row spacing instead of conventional 60-cm row spacing. Low row spacings force farmers to harvest three consecutive rows instead of two alternate rows. This would increase the amount of draft requirement to pull the lifter through the soil. In order to use common medium tractors for pulling the three-unit sugarbeet lifter and properly lifting the sugarbeet tubers out of the soil, applying vibration to the shanks of the lifter was taken into considertion. In this study, the effects of vibration frequency and share rake angle of a vibratory lifter on its performance were investigated. Draft, slippage, percentage of broken and non-harvested tubers were determined for four vibration frequencies (0, 9, 10 and 12 Hz) and three share approach angles (11, 24 and 36 deg.), using a factorial experiment arrangement in a randomized complete block design with three replications. The results showed that the variations in draft and slip with frequency and rake angle were similar. Although the minimum value of draft resistance was obtained at 24 deg. of share rake angle with non-vibrated shanks, 50 percent of tubers remained in the soil and were not harvested. However, the non-harvested tubers reduced to only 20 percent when vibration was applied to the lifter. So using the vibrating shanks improved the removal of the tubers out of the soil. A ratio (K) of draft to the harvested tubers (whole and broken tubers) was defined for selecting the optimum combination of the rake angle and vibration frequency. The K ratio was calculated and analyzed for different combinations of the rake angle and vibration frequency. K ratio comparison showed that, for minimizing percentages of broken and nonharvested tubers, the sugarbeet lifter should have share rake angle of 24 deg. and vibrate with frequency of 9 Hz.

For prevention of soil compaction, knowledge of allowable compression stress limit (compaction strength) in soil is important. Pre-compaction stress ( spc ) was introduced as soil compaction strength and often used as a criterion for evaluation of soil susceptibility to compaction. In this research, pre-compaction stress was measured for a sandy loam soil with plate sinkage (PST) and confined compression (CCT) tests. To prepare soil samples with different initial compactness, two soil water contents (17 and 19%db) and six pre-loading stresses (0, 25, 50, 100, 150 and 200 kPa) were used. The effects of soil water content and pre-loading stress on estimated pre-compaction stress were studied using a factorial experiment in a completely randomized design with three replications. The spc values were significantly influenced by loading combination and soil water content. For PST, pre-load increase and higher soil water content resulted in higher and lower values of spc , respectively. However, predicted spc value increased with higher soil water content for CCT. The results also showed that the spc predicted with PST was accurate, whereas the values obtained with CCT were 4.5 (at 17 %db) and 8.5 (at 19 %db) times higher than the applied pre-loads. Overall, the findings indicated that spc prediction depends on the compression test, and PST could be a suitable method for soil pre-compaction stress (compaction strength) determination in sustainable soil management, i.e., soil trafficability and tillage. The PST method is also suitable to assess the effect of managing factors on pre-compaction stress.

Rice whitening is an important stage in rice milling process and improvement of the whitener machines has a remarkable effect on rice loss. To decrease the amounts of broken rice and losses, the rotor of the blade whitener was equipped with screw conveyor. To investigate the effects of rotor speed (in four levels: 600, 700, 800 and 900 rpm) and output rate (in three levels: 400, 500 and 600 kg/h) on quality of milled rice, a factorial design with randomized complete block experiments with three replications were conducted. In this study, Sorkheh variety (a medium rice variety), which is one of the prevailing varieties in Esfahan, was used. The results showed that the lowest breakage percentage (20.92%) occurred at rotor speed of 700 rpm with an output rate of 600 kg/h and the best degree of milling (6.33%) took place at rotor speed of 600 rpm with an output rate of 400 kg/h. The best rice quality (low broken rice and high degree of milling) was observed at rotor speed of 600 rpm with 500 kg/h output rate.

In order to reduce the adverse effects of sexual maturation on growth and survival of rainbow trout, production possibility of all-female triploid was investigated by means of early heat shock on eggs fertilized by masculinized male’s sperm. Fish ploidy level was determined by erythrocyte size measurement and confirmed by gill nucleolus (NORs) counting as well as chromosome number. Sexual ratios and gonad development were determined by histological studies. Final results showed that progenies produced by mating sex-reversed (masculinized) males and normal females were totally female (100 %). Also, applying early heat shocks (26.5° C lasting 20 min, 20 min after egg fertilization) induced about 80 % triploidy in fishes. All-female triploid, all-female diploid and mixed-sex diploid fishes did not show any significant difference in incubation stages (eyed-stage egg rate, hatching, survival from hatching to active feeding), (P>0.05). Eyed-stage eggs rate, and hatching rate of eyed eggs in mixed-sex triploids were significantly lower than in other treatments (P<0.05). Testes development in diploid males was similar to that of triploid and was in early stages of spermatogenesis in 8 month old fish. Also, diploid ovaries were packed with oocytes at previtellogenic or perinucleolus stages. Although they showed distinct lamellar structure of an ovary, triploid ovaries contained no oocytes.

One of the most important cost factors in forest management, which involves a great deal of investment costs, is road construction. So evaluating forest roads and determining the best one can decrease costs. The objective of this study was to evaluate forest roads using Multi Criteria Evaluation with respect to costs. In Multi Criteria Evaluation method such factors as slope, aspect and soil type were used for suitability map. Then factors were compared in pair-wise comparison in the context of a decision-making process known as the Analytical Hierarchy Process (AHP) to develop weights of map layers. To do this, the opinions of some experts were collected using questionnaires and the results were integrated and factor weights were calculated. Then weights and their factors were entered into Multi Criteria Evaluation (MCE) Module to create final suitability map (factors were standardized before combining). Total costs of each variant were extracted from suitability map. After variant costs were obtained by dividing each variant total cost by its length, unit cost of each variant was calculated. Finally, unit costs were compared and the variant with the lowest costs was determined. The results showed that the slope had the greatest weight followed by soil and aspect. Also, variant 7 had the lowest cost and variant 8 the greatest cost. AHP method has the capability of considering qualitative and quantitative criteria; so it is a proper method for weighting. Also MCE method in GIS environment has the capability of combining different factors. As it requires less time and cost, also has a higher precision, it is better to use MCE method in such studies.

In order to predict Caucasian maple (Acer velutinum Boiss. ) seedling growth based on nursery Orimel, Eighty six one year old seedlings located at 1550 meters above sea level in Sari, north of Iran were randomly selected. Collar diameter, height, leaf area, photosynthesis area and leaf area/leaf weight ratio were determined. Then multivariate regression models between leaf characteristics and growth characteristic were drawn. The results indicated that number of leaves and photosynthesis area can estimate the height growth of a seedling. Also, mentioned characteristics of leaf can estimate the biomass of stem as a well as growth characteristics. According to the correlation between growth characteristics and leaf characteristics, it would be concluded that the photosynthesis area of leaf can be suitable for early selection of seedling for reforestation. Also, this result shows the importance of increasing the establishment and growth of maple seedlings in plantation areas.

The present study discusses a method used to produce updated information about vegetation cover in arid and semi-arid zones, using RS data and GIS technique. In this method, Landsat ETM+ data in 2002 was collected in an area of about 60000 ha in Nodoushan basin, Yazd, Iran. To collect the necessary ground data, 50 sites of different vegetation types were selected and the percentage of vegetation cover in each one was determined. Also, different vegetation and soil indices were derived and crossed with located sampling points using ILWIS software capabilities. To get the best fitted curve, the relationship between vegetation cover, as a dependent variable, and satellite data bands, vegetation indices and environmental factors, as independent variables were assessed. Therefore, a multiple linear regression model was established for the prediction of vegetation cover percentage in the studied area. Finally, a vegetation cover map with high a precision was produced. As a conclusion, it can be said that mapping of vegetation cover via remote sensing is possible even if its vegetation cover is sparse.

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.

The effect of nitrogen and phosphorous fertilization on range species production was studied using factor combination method as factorial with 3 blocks and 12 treatments. Nitrogen in 4 levels of 0*25*50 and 75 kg N/ha and phosphorus in 3 rates of 0*30 and 60 kg N/ha were used. Results indicated no significant difference between nitrogen rates in different growth forms of grass, bush and Eurotia ceratoides. Nitrogen in 75 kg/ha rates caused an increase of 40 and 106% in grass and Eurotia production, respectively. The maximum rate of production was seen in N50 with 100 percent increase compared to N0. Moreover, no significant difference in phosphor rates of leguminous and grass was observed. P 60 kg caused 500 and 56 % increase in leguminous and grass production, respectively.

Ordination is the part of statistical ecology which has developed and integrated in recent years. Finding environmental factors which important in ecological structure determination of plant species is the final purpose of ordination. Ordination method was used for finding the effect of important variables on Bromus tomentellus species quantitative and qualitative changes in Esfahan's Fereidan region. For this purpose, fifteen sites were studied. Density, Cover percentage and Soil factors containing; EC, pH, % caco3 , % gravel and stone, % clay, % silt, % sand, Na+, Ca4+, K+, Mg4+, Cl-, SAR, C/N and % OC. In A (0-30 cm) and B (30-60 cm) horizons over a line transaction in each site, were measured. The matrix of environmental and species characteristics were prepared. The relationship between environmental and species characteristics were determined using of PC-ORD and CANOCO software's and Redundancy Detrended Analysis (RDA) method. The results show that there are meaningful correlation between Density and Cover percentage with soil factors. The results implicate that C/N factor in A horizon and SAR in B horizon have the most effect on Bromus tomentellus density and cover percentage. EC, pH and …. Factors don't have much effect on Bromus tomentellus species characteristics.

In order to determine the effect of climatic factors on distribution of Artemisia aucheri and Artemisia sieberi in Isfahan province, thirty nine most important climatic elements in ecological condition of these species were selected. Using a factor analysis method, the most important factors in distribution of these species were determined. These factors which cover 92.3% of the total variance of spatial variation of the species include rainfall, temperature and shining with 41.91, 40.18 and 10.23 percent, respectively. Four most important vegetative types of Artemisia aucheri and Artemisia sieberi in Isfahan province are as follows: 1-Artemisia aucheri and Astragalus,2- Artemisia sieberi,3-Artemisia sieberi as a dominant species, and 4-Artemisia sieberi as a subdominant species. Then the effects of climatic factors on distribution of these species and the average elevation of distribution of these species were determined. The effect of factor analysis on these types shows that rainfall and temperature are the most influential factors in spatial distribution of Artemisia aucheri and Artemisia sieberi in Isfahan province, respectively. In general, Artemisia sieberi has a higher extended tolerance range than Artemisia aucheri, and could be mentioned as a nearly universal species.

Kerman province is the largest producer of greenhouse cucumber and tomato in Iran. This paper calculates the interest rate of return (IRR) and return period of investment (RPI) in vegetable, cut flowers and strawberry in greenhouse and compares them with vegetable grown outdoors. To do the study, a random sample of 309 farmers was selected in the province of Kerman in 2005. Results showed that IRR for vegetable, cut flowers and strawberry in greenhouse was about 20, 14 and 23 respectively, and it was 45/8 percentage per year for vegetable outdoors. RPI for vegetable, cut flowers and strawberry in greenhouse was about 8, 29, and 7 years, respectively. Vegetables Production under greenhouse produces more employment opportunities, has better yields, higher price and efficient use of factors, but it has lower IRR, higher production cost, higher pesticide residue and is more capital intensive in comparison with outdoor production. Improvement of greenhouse credits, enlargement of metal greenhouses, research on yield and development of greenhouses at region 5 are the important policy-making implications of this paper.

The main objective of this paper is to study the differential impacts of various irrigation water pricing policies. The methodology used is based upon Multi-Attribute Utility Theory (MAUT) mathematical programming models and also simulation. Two kinds of data needed to feed the models were obtained from official records and surveying. The analysis of water pricing policy indicates that the most important relative savings take place in the more conservative farmers due to their risk-aversion behavior. Also it can be seen that in the elastic segments of the demand curves the increase in the price of water encourages great saving in consumption due to changes in mixed crops, crops production by deficit irrigation methods and production of rain-fed crops. Results clearly demonstrate that each homogenous group of farmers displays different behavior patterns related to this natural resource. Therefore, this shows the usefulness of differential analysis in evaluating the impact of water pricing policy.