s. f. mousavi

 Gerbera is one of the most important cut flowers that has a short vase life. Like other cut flowers, one of the main concerns after harvesting this flower is reducing its quality. The application of carbon nanotubes as preservative solutions increase water uptake, balances water relations, and increases the vase life of cut flowers. Agglomeration, lack of proper dispersion, and severe hydrophobicity are the disadvantages of carbon nanotubes that prevent optimal dispersion in the solution. In this study, polymers (polyvinyl pyrrolidone (PVP), polyethylene glycol (PEG), and non-ionic surfactant Triton X-100) were used to increase the dispersion of multiwalled carbon nanotubes (MWCNTs). Their effect on the longevity of cut gerbera flowers was also investigated.

The experiment was performed as a factorial experiment in a completely randomized design with four replications. Gerbera (Gerbera jamesonii cv. Rosalin) flowers with fully opened ray florets were purchased. During transportation, each cut flower was covered individually with a cellophane sheet and was placed inside a box of paper to minimize water loss. Gerbera stems were placed in a vase solution as pulse treatment for 24h. Treatments included various concentrations of nanocomposite including control (distilled water), MWCNTs-PVP nanocomposite (1 and 2 mg L-1), MWCNTs-PEG nanocomposite (1 and 2 mg L-1), and MWCNTs-Triton X-100 nanocomposite (1 and 2 mg L-1). Distilled water was used for the control treatment. After the cut gerbera flowers underwent pulse treatment, they were placed individually into glass vases filled with distilled water. Throughout the experiment, the vase life, relative fresh weight, water uptake, relative water content of petals and stems, as well as the bacterial population at the end of the stem were measured.

 The study showed that the MWCNTs-Triton X-100 with a concentration of 2 mg L-1 provided the longest vase life of cut flowers, with a duration of 22.5 days, which was an 8-day increase compared to the control. The other nanocomposites (MWCNTs-PVP and MWCNTs-PEG) also improved the longevity of the cut flowers compared to the control. The nanocomposites in the vase solution affected the relative fresh weight and water uptake of the cut stems. The study found that the water uptake pattern was similar to the fresh weight of the flower, and the water uptake capacity of the stem gradually decreased with time. The MWCNTs-Triton X-100 with a concentration of 1 mg L-1 resulted in the highest amount of water uptake. Cut flowers pulsed with this concentration exhibited the highest relative water content in both petals and stems. The application of MWCNTs-PEG nanocomposite (1 mg L-1) in vase solution increased the relative fresh weight of gerbera cut flowers. Our findings suggest that MWCNTs can increase water uptake, resulting in increased fresh weight in the cut stem. SEM analysis revealed that after the evaluation period, MWCNTs were detected in the stem of cut gerbera and deposited on the stem's internal surface. Our finding showed that the bacterial population at the end of the stem in control treatment during the vase life period was higher than the bacterial population at the end of the stem of flowers treated with MWCNTs-Triton X-100 treatment (2 mg L-1). Therefore, reducing bacterial blockages in the xylem vessels improves the water uptake and vase life of cut flowers.

 When gerbera cut flowers are harvested and kept in vase solutions, they face some challenges including wounding and water stress. Continuity of water flow in cut flower stem after cutting is an important factor in determining postharvest quality and longevity of cut flowers. Applying a solution containing well-dispersed MWCNTs is a novel approach for facilitating the entry of this nanotube into plants. The use of a composite of MWCNTs with X-100, PVP, and PEG exhibits excellent dispersion properties in the aqueous media of vase solution. These nanocomposites were successful compounds in increasing water uptake, maintaining fresh weight, and increasing the vase life of gerbera cut flowers. The findings of the present study showed that nanocomposites inhibit bacterial growth. These results suggest that the elimination of barriers to water flow in the cut stem helps to keep the longevity and delayed senescence.

Nowadays, the prediction of river discharge is one of the important issues in hydrology and water resources; the results of daily river discharge pattern could be used in the management of water resources and hydraulic structures and flood prediction. In this research, Gene Expression Programming (GEP), parametric Linear Regression (LR), parametric Nonlinear Regression (NLR) and non-parametric K- Nearest Neighbor (K-NN) were used to predict the average daily discharge of Karun River in Mollasani hydrometric station for the statistical period of 1967-2017. Different combinations of the recorded data were used as the input pattern to predict the mean daily river discharge. The obtained esults  indicated that GEP, with R2= 0.827, RMSE= 59.45 and MAE= 26.64, had a  better performance, as compared to LR, NLR and K-NN methods, at the  validation stage for daily Karun River discharge prediction with 5-day lag, at the Mollasani station. Also, the performance of the models in the maximum discharge prediction showed that all models underestimated the flow discharge in most cases.

In the last few decades, the use of porous concrete to cover the sidewalks and pavements as an interface to collect the urban runoff has been increased. This system is economically more efficient than other runoff-pollution reduction methods. To design a runoff control system and reduce its pollution, it is necessary to determine the hydraulic and dynamic properties of the porous concrete (with and without additives). In this research, the effects of cement type (2 and 5), water to cement ratio (0.35, 0.45 and 0.55), fine grains percent (0, 10 and 20%), the type of additive (pumice, industrial pumice, perlite and zeolite), and the added additive percent (5, 10, 15 and 20%) on the physical properties of the porous concrete (porosity, hydraulic conductivity and compressive strength), each with three replications,  were  investigated using robust design. Qualitek-4 software was also used to discuss the results. The results showed that to obtain the highest porosity in the mixing scheme of the porous concrete, no fine grains, cement type 2 and 15% industrial pumice should be used, and water to cement ratio should be 0.35. Also, the water to cement ratio of 0.55, 0% fine grains, type 2 cement and 15% industrial pumice resulted in the highest value of hydraulic conductivity in the porous concrete. Finally, the water to cement ratio of 0.55, 20% fine grains, type 2 cement and 5% zeolite led to the maximum compressive strength. In general, it was not possible to reach a logical conclusion in this research with the least costs without employing the robust design.

One of the appropriate procedures to increase discharge capacity of spillway in dams, particularly when increase of overflow width is not possible, is using labyrinth spillways. Due to the fact that a considerable portion of costs of dams is allocated for construction of spillways, the search for methods to optimize these structures becomes important. In the present research, the Cuckoo Search (CS) algorithm has been used to find the best geometry of the trapezoidal labyrinth spillway. For this purpose, concrete volume of the spillway was considered as objective function. Aslo, the spillway design considered different hydraulic constraints. Optimal parameters of this algorithm were selected by performing sensitivity analysis. Then, CS was run randomly for 15 iterations. The coefficient of variation and convergence speed obtained from random runs for the proposed algorithm were equal to 0.00001 and 1000 iterations, respectively. Finally, minimum value of the objective function of the proposed algorithm was compared to the results obtained from spillway design and the results of Genetic Algorithm (GA) and Differential Evolution (DE) proposed in the previous studies. It was found that the proposed spillway dimentions using CS resulted to 38.91% less concrete with respect to the real prototype. In the proposed model, other than reduction of the spillway concrete volume, the overflow discharge of the spillway was increased. On the other side, concrete volume reduction obtained by CS was 12% less than classic optimization algorithms (GA and DE). Considerable decrease (more than 1/3) in the volume of concrete in the proposed spillway indicates high ability of CS in solving the problems of optimizing spillways and the necessity of using it.

Nowadays, due to increased water consumption and demands, optimum water allocation should be taken as a serious need. In this research, WEAP and Vensim softwares are used to plan and manage the water resources and demands in Nazloo River basin, located in West-Azarbaijan province. By use of these softwares, two models were prepared: One for supplying water demands of the region using river flows (without Nazloo dam) and the other one with the same condition but by considering the Nazloo dam operation effect. Water demands of the region were assessed up to 2016, river flow of the past 40 years was analyzed, and river discharge of 2013-2016 was estimated by ARIMA method. Results showed that average differences between the results of WEAP and Vensim softwares were 3.74% and 8.91% for the with-dam and no-dam options, respectively. The highest water deficiency was in water supply to agricultural demand in September, which with construction of the dam, the average supply in this month increases from 15.8% to 94% of the demand amount. To verify the obtained results of the unmet water demand in various years, the SPI index was used, which in 72.5% of the cases it was consistent with the results of the softwares. In general, without constructing the dam, water needs of industry and environment will be mainly supplied, but there would be some deficiencies in water supply for agriculture. For water supply, instead of constructing a dam with a storage capacity of 154 MCM, a dam with a capacity of 100 MCM will be enough.

Influenza vaccine is one of the best ways to prevent and control influenza worldwide. It is manufactured by WHO-licensed companies based on the WHO expertise committee annually. The aim of this study was partial quality control of the commercial human influenza vaccine 2008-9 and its matching with the circulating strains. The trivalent imported vaccine was cultured in bacterial and fungal media, injected to the mice and inoculated into the allantoic cavity of Embryonated Chicken Eggs (ECEs). hemagglutination-inhibition (HI)assay was carried out on pre and post vaccination serum samples. The bacterial endotoxin was assessed by LAL assay. The hemagglutinin (HA) content of the vaccine was measured using SRID. Heterogenecity of the circulating influenza strains during 2008-9 seasons in Tehran in comparison to the vaccine strains was determined. No bacterial contamination and no occurrence of mortality and morbidity in animal was observed. The mean fold increase of HI antibody titer in subjects without previous vaccination for H1N1, H3N2 and B strains were 6.7, 3.3 and 1.8 respectively, while in subjects with previous vaccination were 4, 1.6 and 1.1 for same strains. Amino acid variation was found in Tehran H1N1 isolates but the H3N2 isolates showed higher genetic resemblance to the 2008-9 vaccine strain. The sterility, safety, and efficacy of the vaccine were approved and there was some variation in A/H1N1 but not in A/H3N2 isolates in comparison with the vaccine strain.

Puddling is the most common method of land preparation for lowland rice cultivation. The purpose of this study was to assess the influence of various intensities of puddling on percolation rate، water retention by soil and the amount of water used for different puddling intensities in three dominant soil textures of paddy fields in Guilan province. Undisturbed soil samples were taken from 3 different soils including silty clay، clay loam and loam، with 3 replications. The soil samples were puddled by a laboratory apparatus with different intensities. The results showed that the low puddling intensity treatment caused a 29. 3، 32. 4 and 36% reduction of percolation rate in silty clay، silty loam and loam textures، respectively. Increasing puddling intensity from low to medium reduced percolation rate significantly، but high intensity was not effective. Soil moisture characteristic curves of all three soils showed that water retention was increased by puddling treatments. Water retention in silty clay was higher than the other two soils. The high intensity treatment needed more water than low intensity for puddling. Increasing puddling intensity from medium intensity to high intensity caused 15. 4، 14. 1 and 16. 3% increase in the amount of water required for puddling in silty clay، silty loam and loam textures، respectively. Generally، in all the three studied soil textures، the amount of water used for high-intensity puddling was more than medium-intensity puddling، while it had no significant effect on water percolation rate and soil water retention.

Influenza A virus infects birds and some mammalian including human. H1 and H3 subtypes are circulated in both human and birds’ population. To determine the prevalence of the mentioned subtypes in birds, different captive bird species in Tehran zoo, and affiliated centers in Tehran were investigated for virus infection. In this study, Between November 2008 and February 2009, 76 cloacal swabs and serum samples were collected from 5 orders of Anseriformes, Galliformes, Columbiformes, Pelicaniformes and Phoenicopteriformes. Antibody surveillance was undertaken by haemagglutination inhibition assay and for detection of influenza virus genome RT-PCR technique was used. In total, 57.7% and 88.75% of bird sera were seropositive against H1 and H3 viruses respectively. The highest GMT value and the greatest antibody titers were observed in Galliformes order particularly in chicken species. Influenza A genome was not detected in any of the samples by RT-PCR using M gene. Results of this study indicated that seropositive birds were infected during the last or possibly previous years with H1 and H3 virus strain.

One of the problems in design of irrigation structures is sedimentation control in the inlet to the irrigation networks. Water quality for agriculture requires that the sediments be controlled and reduced to the permissible limit at their entrance point to the turnouts and irrigation networks. This is possible by constructing a sedimentation basin. The bigger the basin, the best the retardation of the sediments, but the expenses are higher too. Different mathematical models are developed for sedimentation basins. Most of these models show the relationship between efficiency and effective parameters by mathematical formulas. In this research, a computer software for design of settling basins was designed in which design parameters (length, width, depth, slope and water velocity in the basin) are determined such that the basin has the specified technical characteristics and it is built with minimum cost. In this respect, operations research and a lexicographic enumeration algorithm is used. Application of this software for evaluation of construction costs of sedimentation basins in Nekouabad diversion dam Zayandehrud irrigation networks at Isfahan) showed that efficiency of these basins is 50.6% and 46.5%. If these basins were built under optimum design, about 18% and 6% would have been saved in their construction costs, respectively.

In order to study the effects of irrigation regimes and plant spacing on bulb yield of two onion (Allium cepa L.) genotypes, an experiment was conducted at Kabootar Abad Research Station of Isfahan during two growing seasons (2005 and 2006). The experiment design was split-factorial with a randomized complete block arrangement with four replications. Main plots included three irrigation regimes (irrigation after T1= 503 mm, T2= 703 mm and T3= 903 mm evaporation from class A pan). Sub-plots formed from factorial combination of two spring onion genotypes (Yellow Sweet Spanish and Dorcheh-Isfahan) with three plant spacing in rows (5, 7.5 and 10 cm). The results showed that total yield, marketable yield, bulb diameter and bulb height decreased as irrigation frequency increased. The highest total yield (6.867 kg/m2) and marketable yield (5.761 kg/m2) were produced in T1 treatment. Regarding total yield, the response of genotypes to increasing irrigation frequency was different. The Yellow Sweet Spanish genotype tolerated water deficit more than Dorcheh. Total yield, marketable yield and bulb height in Yellow Sweet Spanish genotype were significantly greater than Dorcheh, but diameter of bulb neck, dry matter and total soluble solids in Dorcheh were significantly greater than Yellow Sweet Spanish. Among the plant spacings, the 10 cm spacing had the lowest total and marketable yield and there were no significant differences between 5 and 7.5 cm spacing. But bulb size (height and diameter) increased as plant spacing increased.

Water scarcity and soil salinity are two important limiting factors for agricultural production.Canola crop, with high resistance to soil salinity and adaptation to different climatic conditions of Iran, has great ability for satisfying the main part of the country’s requirements for edible oil.This research was carried out in 2006 on winter canola (Brassica napus L., cv. Zarfam) under greenhouse condition at the Agriculture and Natural Resources Research Center, Yazd. The experiment was performed as a complete randomized block design with three replications that contained salinity and irrigation water factors. Salinity factor had four levels of S1=3-4, S2=6-7, S3=9-10 and S4=12-13 dS/m and irrigation water factor had three levels of irrigation after W1=30, W2=50 and W3=80 percent of management allowed moisture depletion. Soil texture was sandy loam. The results showed that salinity and deficit irrigation were significantly effective on dry matter production (p<0.05). Under simultaneous salinity treatments and deficit irrigation,increasing salinity to S3 significantly increased the canola dry matter by 14.6% and increasing salinity to S4 level decreased the plant dry matter production by 10.9%. Dry matter of W3 treatment was 6.5% less than W1 treatment. Deficit irrigation and the combined impact of salinity and deficit irrigation did not have significant effect on nutrient (P, K, Ca and Mg) content. Salinity effect was significant (p<0.01) on Na, Cl and Zn content. S3 and W2 treatments had the highest amount of Cu, Zn and Fe. Study of soil salinity at the end of the experiments showed that 0-5 cm soil layer has the highest salinity level; salinity of the middle layer (5-10 cm) is less than the other two layers and the salinity of 10-20 cm is higher than the middle layer and lower than the upper layer.

Soil erosion is an important economical, social and environmental problem requiring intensive watershed management for its control. In recent years, modeling has become a useful approach for assessing the impact of various erosion-reduction approaches. Due to limited hydrologic data in mountainous watersheds, watershed modeling is, however, subject to large uncertainties. In this study, SWAT2000 was applied to simulate runoff and sediment discharge in Beheshtabad watershed, a sub-basin of Northern Karun catchment in central Iran, with an area of 3860 km2. Model calibration and uncertainty analysis were performed with SUFI-2. Four indices were used to assess the goodness of calibration, viz., P-factor, d-factor, R2 and Nash-Sutcliffe (NS). Runoff data (1996-2004) of six hydrometery stations were used for calibration and validation of this watershed. The results of monthly calibration p-factor, d-factor, R2 and NS values for runoff at the watershed outlet were 0.61, 0.48, 0.85 and 0.75, respectively, and for the validation, these statistics were 0.53, 0.38, 0.85 and 0.57, respectively. The values for calibration of sediment concentration at the watershed outlet were 0.55, 0.41, 0.55 and 0.52, respectively, and for the validation, these statistics were 0.69, 0.29, 0.60 and 0.27, respectively. In general, SWAT simulated runoff much better than sediment. Weak simulation of runoff at some months of the year might be due to under-prediction of snowmelt in this mountainous watershed, model’s assumptions in frozen and saturated soil layers, and lack of sufficient data. Improper simulation of sediment load could be attributed to weak simulation of runoff, insufficient data and periodicity of sediment data.

Iran, with an average annual precipitation of about 252 mm (413 BCM) and renewable freshwater resources of 130 BCM, has irregular distribution of water resources. With a high population growth rate, agriculture remains the greatest water user in Iran but its production still does not meet the total food demand of the country. Due to unreliable water availability, the competition for water from other sectors and the increasing demand for food and better diets, Iran will experience water stress. In this study, virtual water trade in relation to water resources availability has been assessed as a way of relaxing water stress in Iran. The results showed that from the 21 food products, cereals, pulses, nuts and oilseeds are water-intensive crops according to their estimated virtual water content, while fruits, vegetables and industrial crops are not water-intensive. Considering the volume of virtual water entering the country through food imports, more water will be available for other essential uses. However, the virtual water trade has been developed rather unconsciously regarding water use and crop water productivity during the past two decades. For instance, wheat with a share of 58.5% in the virtual water import to Iran, was the dominant imported crop during 1983-2003. By importing 10.4 Mt of wheat, 11.6 BCM of water has been saved within the country during 1999-2003. However, Iran became self-sufficient in wheat production in early 2005. Consequently, this latest drive for self-sufficiency in the production of wheat, as a water-intensive crop, put tremendous pressure on domestic water resources. The trend in crop trade in terms of quantity and virtual water for other groups of crops has also been shown in the study. Seemingly, crop production and import have been greatly influenced by the weather conditions. With the increasing water scarcity, the role of virtual water in food security is expected to rise continuously in Iran. Thus, conscious virtual water trade as a policy measure in water management and judicious adjustment in agricultural structure will ensure sustainable food security and water availability in Iran.

After construction of a dam across a river, sediments settle behind the dam. It is important for dam designers to estimate the rate and distribution of sediments in the reservoir. In this study, the accuracy of area-increment and area-reduction empirical methods to predict the sediment distribution of Dez, Dorudzan and Shahid Abbaspour reservoirs is evaluated. The last measurement of sediment in these reservoirs was in 2003 (Dez), 2005 (Dorudzan) and 2005 (Shahid Abbaspour). The comparison between actual sediment distribution and predicted sediment distribution by using area-increment and area-reduction methods showed the maximum error at the depth of sediment behind the dam. At higher elevations, the error decreased and reached zero when the elevation was maximum. For Dorudzan reservoir, which has the least sediment volume (31 Mm3), the area-reduction method is less accurate, as compared to the area-increment method (81% vs. 37.5%). For Dez and Shahid Abbaspour reservoirs, where their sediment volume is high (608 and 737 Mm3, respectively), the error of the two methods is relatively equal (in Dez, 29% for both methods, and in Shahid Abbaspour, 22% for area-reduction and 25% for area-increment methods). After long-time sedimentation, the shape factor decreased and reservoir type of all three reservoirs changed to 2.

In order to investigate the relationship between plant density and grain yield of three pinto bean cultivars at three different sowing dates, a split plot factorial experiment based on randomized complete block design (RCBD) and three replications was conducted in Zanjan Agricultural Research Center in 2003. Three pinto bean cultivars (Talash, Khomein 5 and COS16) at three different sowing dates (9 May, 21 May and 2 June) with four densities (15, 20, 25 and 3 plants/m2) were sown in a loamy soil. Days to flowering, pods per plant, seeds per plant, 100 seeds weight, days to maturity and grain yield were significantly affected by sowing date, cultivar and plant density. The interaction effects of sowing date and cultivar were olso significant for days to flowering, days to maturity and grain yield but interaction effects of sowing date and plant density were only significant for days to flowering and grain yield. All these traits were decreased with delaying in sowing date. Grain yield of COS16 was higher than that of Talash and Khomein 5. Days to flowering, pods per plant, seeds per plant, 100 seeds weight and days to maturity decreased, but empty pods per plant and grain yield per unit area increased, with increasing plant density. The relationship between plant density and grain yield of the three pinto bean cultivars were analysed, using equations 1/w = a+bp and y = p/a+bp, where: 1/w = reciprocal of yield per plant, y = grain yield per unit area, p = plant density, a and b = constants. The results indicated that delayed sowings reduce grain yield of low densities more than that of high densities. Consequently, estimated optimum economic densities for delayed sowings were more than those for early sowings. Therefore, it is necessary to increase seeding rate at delayed sowings, in order to prevent or to reduce the yield loss.

To investigate yield and water use efficiency (WUE) of potato with tape and furrow irrigations, an experiment was performed at Hamadan Agricultural and Natural Resources Research Center (Ekbatan station) in 2004. The experiment was arranged in a split-plot experimental design based on completely randomized block with 3 replications of irrigation water amount as the main factor (75%, 100%, 125% of cumulative evaporation from class A pan) and sub-factor of irrigation method [including tapes in the middle of furrow ridge on soil surface (TD0), tapes in the middle of furrow ridge at the depth of 5 cm (TD5), tapes on the sides of furrow ridge on soil surface (TS0), and furrow irrigation (F)]. The results indicated that yield of potato increased with increasing water use. Regardless of irrigation method, maximum (32.51 ton/ha) and minimum (19.33 ton/ha) yield of potatoes was achieved with 125% and 75% irrigation water treatments, respectively. The lowest yield (21.35 ton/ha) was obtained in furrow irrigation and the highest yield (28.91 ton/ha) belonged to tape irrigation (TD5 treatment). The highest WUE (4.68 kg/m3) belonged to tape irrigation (TD5 treatment) and the lowest WUE (3.32 kg/m3) belonged to furrow irrigation (F). The difference in WUE between 75% and 100% irrigation water treatments was not significant. The highest WUE (4.49 kg/m3) was achieved in treatment 125%. Also, it is more economical to use irrigation water treatment of 125%, as compared with other irrigation water treatments.

Accumulation of heavy metals (HMs) in cultivated soils is an important environmental problem in many parts of the world. In recent years, HM leaching through preferential paths and also in the form of metal-organic acids complexes has received much attention. For this reason, the effects of plants on creating preferential flow through the soil is important. The objective of this study was to assess the mobility of Cd, Cu, Pb and Zn in a calcareous soil (Typic Haplocalcids) planted with safflower (Carthamus tinctorious). The study was conducted on 12 undisturbed soil columns (22.5 cm in diameter and 50 cm in depth) in greenhouse. The top 10 cm of soil in half of the columns were contaminated with Cd, Cu, Pb, and Zn at the rates of 19.5, 750, 150 and 1400 kg ha-1, respectively. Half of the contaminated and uncontaminated columns were planted with safflower at a rate of 20 seeds m-2. Leachate was collected continuously and analyzed for these four heavy metals. After the crop harvest, soil samples were taken at 10 cm intervals and analyzed for DTPA-extractable and water-soluble HMs concentration. Results showed that heavy metal concentrations (DTPA and soluble) of the subsoil in planted columns were more than in fallow columns. The DTPA-extractable Cd, Cu and Zn concentrations in contaminated planted columns were 3.3-, 1.5- and 1.5-times more than in contaminated fallow columns, respectively. The water-soluble Cd, Cu and Zn in planted treatments increased 2.4, 1.2- and 1.1 times more than the fallow treatment. Lead concentrations in both planted and fallow treatments were similar. Metal uptake by safflower increased such that Cd and Zn uptake was more than Cu and Pb. Cd, Cu, Pb and Zn concentrations in the leachate of planted columns increased 32.0-, 2.5-, 6.0- and 2.7- time more than the uncontaminated planted columns. In summary, although topsoil contamination increased metal uptake by safflower, however the presence of safflower increased DTPA-extractable and also soluble metal concentrations in the soil profile and therefore enhanced metal mobility. The order of metal mobility was Cd > Zn >Cu >Pb.

Cultivation of a second crop in paddy fields of Guilan province is a strategy for optimum use of land, supporting family economy and increasing oil-seed production. However, this is impeded under high rainfall and waterlogging conditions. To enhance second-crop cultivation in paddy fields, surface drainage is inevitable. The surface drainage practices should be performed with minimum costs, least time span and least variations of the land. In the present research, longitudinal surface drains were constructed with a spacing of 2, 4, 6, 8 and 10 m (depth of 20 cm), with and without 1-m lateral drains (depth of 10 cm) in Rice Research Institute, Rasht, Iran. The experiment was conducted in a complete randomized block design with three replications. Canola (Brassica napa), variety PF, was cultivated as a second crop after rice. The results showed that the effects of drain spacing on seed yield, days to maturity, number of plants per m2, and also the effects of lateral drainage on seed yield, plant height, residual N, days to maturity, and number of plants per m2 are significant (P<0.01). Highest yield (2493 kg/ha) was obtained from longitudinal drains 4 m apart, with lateral drainage drain spacing of 6 and 2 m had acceptable yields, too (2241 and 1817 kg/ha, respectively). For treatments without lateral drainage, 2-m drain spacing had the highest yield (1324 kg/ha). Considering all the expenses for drainage construction, it was found that net benefit of longitudinal drain spacing of 4 and 6 m was twice the costs. Since the rainfall in Nov., Dec., and Jan., 2000, was higher than the 20-year average rainfall of the same months, it was concluded that the results of this experiment may be recommended in the years with a rainfall less than the year 2000.

Because of slight variation of the static head due to discharge fluctuations, the labyrinth weirs are considered to be economical structures for flood control and water level regulation in irrigation networks, as compared to other devices. Labyrinth weirs are composed of folded sections observed as trapezoidal and triangular in plan view. In this study, rectangular and U-shaped labyrinth weirs were investigated. Experiments were conducted on 15 labyrinth weir models. The models included eight rectangular labyrinth models and six U-shaped labyrinth models with different heights and lengths, and one linear model. All the experiments were performed in a horizontal rectangular flume, 7 m long, 0.32 m wide and 0.35 m high. The results indicated that for all the models, discharge coefficient increased sharply with an increase in Ht/P and attained a maximum value. This coefficient then decreased smoothly with a further increase in Ht/P. Increasing height of weirs increased the discharge coefficient for both rectangular and U-shaped weirs. The results also showed that increasing the length parallel to the flow direction decreased and increasing the length perpendicular to the flow direction increased the discharge coefficient. Generally, the discharge coefficient for rectangular weir was less than that of the U-shaped weir. The obtained results compared with those of Tullis et al. (1995) showed that discharge coefficient for U-shaped weir is more and for rectangular weir is less than that of the trapezoidal weir for angle of the side legs of 8 and 12 degrees.

In recent decades, the use of nitrogen fertilizers has increased irrespective of their effects on soil properties, agricultural products and, particularly, on environmental pollution. Nitrate easily leaches from soils into groundwater. The objective of this study was to determine temporal and spatial nitrate concentrations in groundwater in agricultural, industrial and urban regions in some parts of Isfahan Province. Water samples were collected monthly from 75 agricultural, industrial, and urban wells of Isfahan, Najaf-abad, Shahreza, Natanz and Kashan during January-May 2001. The results indicated that NO3-N concentrations in most of the regions studied were higher than the standard level (10 mg/l) and nitrate pollution must be reckoned among the most serious problems of sustainable agriculture and exploitation of groundwater resources. Average NO3-N concentration in different wells ranged from 1.03 to 50.78 mg/l (4.64 to 228.5 mg/l as nitrate). The average NO3-N concentration in groundwater of Najaf-abad, Shahreza, Isfahan and Natanz-Kashan was 17.56, 14.6, 16.04, and 8.24 mg/l and 95.5, 100, 84 and 33.3 % of total wells in these regions had nitrate concentrations above the standard level, respectively. Maximum NO3-N concentration was detected in the agricultural region south of Najaf-abad (64.6 mg/l). Nitrate pollution in most of the sampling areas was mainly linked to agricultural activities. The average NO3-N concentration in groundwater of all agricultural, industrial, and urban regions, except for urban regions of Natanz and Kashan, were above the standard level. Generally, nitrate concentration level in groundwater increased with time and was maximum in March and April.

The objective of this research was to evaluate bromide leaching in a field under corn, wheat and alfalfa. Potassium bromide (300 kg/ha) was uniformly applied and 15 mm of water was sprinkled over the plots in the first and second years. Plots were leached 8 times during the first year and 9 times in the second year (each time with 100 mm of water). Soil samples were collected at 0-30, 30-60, 60-90 and 90-120 cm depths two days after each leaching practice. Bromide concentration in soil samples was measured using an ion selective electrode. Moisture content in each plot was measured using a neutron meter to a depth of 120 cm and after calculation of evaporation from soil surface, the net water applied was determined. CXTFIT software and Regional Stochastic Model (RSM) were used to simulate leaching under field conditions. The results showed that flow velocity and dispersivity of treatmens were not significantly different from the control in the first year, indicating that treatments had no effect on preferential flow. Control treatments were not significantly different in the first and second years. In the second year, flow velocity in wheat, corn and alfalfa treatments were 1.54, 1.86 and 2.21 times higher than flow velocity in the control, respectively. Dispersivity in alfalfa and corn treatments were 4.30 and 5.30 times higher as compared to the control. The increase in flow velocity and dispersivity is caused by an increase of preferential flow in the second year. The root channels remaining in soil at the end of the first year may also have increased preferential flow. After adding 25 cm of water, 30% of bromide leached from the top 50 cm soil in all plots in the first year and control plots in the second year but the values in the second year were 47, 67 and 70% of bromide leaching from the top 50 cm soil in wheat, corn and alfalfa plots, respectively.

Life in central Iran depends on the Zayandehrood river, making the preservation of its quality important. Salinization and pollution of the flow as a result of different organic and inorganic pollutants create serious threats to the environment and to the agricultural activities in the region. Although the role of the main drains discharged into the Zayandehrood in changing its quality is well known, little information is available on the volume and quality of the discharged drains. The purpose of this research was to study the quantity and quality of three main drains (Zoab-Ahan, Rudasht and Segzi) discharging into the Zayandehrood, Monthly samples were taken from each drain and their chemical properties were measured in 1998. The discharge rates were also measured simultaneously at sections near the discharge points. The results showed that all three drains were alkaline and, therefore, had no negative effects on the pH of the river flow. Mean annual EC of Zoab-Ahan, Rudasht and Segzi drains were 5.56, 27.18 and 42.41 dS/m, respectively, and the salt loads discharged into the river by these drains were 39258.4, 37672.9 and 259781.2 ton/year, respectively. Annual mean N concentrations were 4.49, 3.92 and 4.18 mg/L and annual mean P concentrations were 0.26, 0.16 and 0.12 mg/L in the drains, respectively. The most important effect of the drains on the Zayandehrood was salinization, especially in the lower parts of the river. The increase in soluble salt contents of the river after Segzi drain discharge was so high that it made the water thereafter unusable for any purpose.

A study was conducted to determine irrigation scheduling of pinto bean and to evaluate the effect of its planting date. A split-plot with complete randomized block design with four replications was used at Isfahan University of Technology Research Station in Shervedan-Falavarjan, The main plots were three irrigation regimes of T1 to T3 (irrigation after 50±3, 70±3 and 90±3 mm evaporation from class A pan, respectively) and the sub-plots were two planting dates of May 28 and June 28. The results showed that delayed planting from May to June caused earlier flowering, physiological maturity and reduction of 29.6% in grain yield. Grain yield in T1 to T3 treatments were 3585.1, 3510.5 and 1925.8 kg/ha, respectively. The difference between grain yields of T1 and T2 with T3 treatments were significant at 1% probability level. Biological yields at May 28 and June 28 planting dates were 8257.1 and 5535 kg/ha, respectively, which were significantly different. There was no significant difference between biological yields of T1 and T2 treatments. Number of pods per square meter was the most important component of grain yield and 85% of grain yield difference was due to this part. Harvest index was affected by irrigation treatment and planting date. Mean harvest indices for T1 to T3 treatments were 45.5, 46.1 and 37%, respectively, and 42.8% and 44.9% for the two planting dates. Water use efficiencies for grain yield in T1 to T3 treatments were 0.557, 0.556 and 0.329 kg/m3, respectively. Generally, treatment T2 was shown to be the best irrigation regime.