Journal of Water and Soil Science
Year:2004 | Volume:8 | Issue:3|Papers Count:22

To obtain soil-moisture characteristic curve experimentally is time-consuming and usually subject to considerable errors. So, many investigators have tried to predict soil-moisture characteristic curve by different models. One of these models predicts soil moisture characteristic curve based on soil particle size distribution and bulk density. In this model, soil particle size distribution curve is divided into a number of segments, each with a specific particle radius and cumulative particle mass greater than that of the radius. Using these data, soil-moisture characteristic curve was estimated. In this model, a scale factor, a , is used which may be considered as a constant, or obtained by logistic or linear procedures. The average values of a for clay, silty clay, sandy loam, two loam soils, and two silty clay loam soils were 1.159, 1.229, 1.494, 1.391, 1.393, 1.253 and 1.254, respectively. For most conditions, soil particle size distribution curve is not available, but only the percentages of clay, silt, and sand could be obtained using soil textural data, which is not enough to draw a precise soil particle size distribution curve. In this situation, a precise soil particle size distribution curve must be initially developed on the basis of which the soil moisture characteristic curve can be predicted. In this study, using soil textural data of seven different soils, soil moisture characteristic curve of each was estimated. In these estimations, logistic and linear methods were used to obtain the a value. Then, the results were compared with those of measured soil moisture characteristic curve. For estimation of soil particle size distribution curve, two extreme values for soil particle radius, 125 and 999 mm, were used.The results indicated that using particle radius of 999 mm is more appropriate. On the other hand, it was found that for clay, silty clay, and sitly clay loam texture, it is more appropriate to employ a linear equation to determine a for estimating soil-moisture characteristic curve while the logistic equation can be more appropriately used for loam and sand loam textures.

Hydraulic coefficients of a porous media such as hydraulic conductivity K(q) and diffusivity D(q) have a controlling role in the evaluation of groundwater flow and pollutant transport behavior. Therefore, successful porous media flow evaluation depends on the accurate determination of its hydraulic coefficients. But it is hard and time consuming to measure. Values for these coefficients accurately as measurements usually task place at a moisture range close to saturation. This situation justifies the preference for prediction models to be used. One method for evaluation of K(q) and D(q) coefficients is to use models which take measured soil moisture characteristic curve data into consideration. For the purposes of the present study, pressure plates apparatus measured the required data to develop soil moisture characteristic curve for nine various soil textures. The volume of instantaneous outgoing water was measured with respect to time and the total volume of water released at the end of each experiment was measured for a given pressure (0.1 to 1.5 Mpa) imposed on undisturbed soil samples.A simple equation based on Richard’s equation is provided for the estimation of K(q) and D(q). Application of Mualem, van Genuchten et. al, Burdine, Green and Corey, and Gardner models for estimation of the K(q) and D(q) values at a variety of nine varied soil textures under experiment showed a wide range of variation. Therefore, it is hard to simulate the accurate hydraulic conductivity behavior for the given varied soil textures by means of the models available. However, if the minimum and maximum simulated values obtained from the models at respective soil moisture contents are considered to be a permitted range, one may state that the results of the estimated hydraulic coefficients by the proposed method in this study lie within the permitted range or agree with the results of other models considered. Therefore, the proposed method for determination of K(q) and D(q) is capable of selecting the best simulation model to estimate hydraulic coefficient values.

Water crisis is an important issue in arid and semi-arid regions like Iran. The situation has been getting more worse over recent years drought. Hence, there is a growing need to utilize low quality water where freshwater is scarce. In this regard, urban wastewater is a promising source but there are concerns about the environmental and health aspects of using such water. The main problem regarding the performance of trickle irrigation system utilizing wastewater effluents is clogging of the emitters. In this study, field trials at pilot scale were carried out to investigate the hydraulic properties of emitters using two types of water including treated wastewater and groundwater. The trickle irrigation system consisted of three 16 mm lateral tubes placed at 300 mm spacing in the main tube and each lateral tube had 16 emitters at 300-mm spacing. The designed discharge of the emitters was 4 L/h. The hydraulic properties of the different commercial emitters (micro flapper, long path, turbo plus and Eurokey) were assessed at different time periods.The results indicated that the Eurokey and long path emitters had the maximum and minimum emission uniformity, respectively, when applying wastewater. using groundwater, the Eurokey and turbo plus emitters had the maximum and minimum emission uniformity, respectively, during the initial phase of the study. However, the Eurokey and long pathemitters had the maximum and minimum uniformity values, respectively, at the end of the study. The turbo plus emitters are regulated and, as a result, showed no evidence of sensitivity to pressure variations; hence, they can be used on uneven lands and where the trickle irrigation system has long lateral tubes.

The significance of haploid plants as genetic and plant breeding tools has been recognized for a long time. Haploid production techniques including anther culture, isolated microspore culture and intergeneric hybridization between wheat × Hordeum bulbosum and wheat × maize have been used to produce homozygous lines which accelerate breeding programs. In this study, wheat × maize hybridization and anther culture techniques were used for haploid production in six wheat genotypes.The results showed that 70.7% of regenerated plants through anther culture were albino plants and only 29.2 % were green, while the plants produced through wheat × maize method were all green. Ploidy variation was not observed in plants regenerated through wheat × maize hybridization. It was concluded that wheat × maize crosses would be an appropriate and practical method for haploid production in different wheat genotypes, which in comparison with the anther culture method has a higher efficiency.

Soil pollution and accumulation of heavy metals in crops in industrial areas are the most important bioenvironmental problems that threaten the life of plants, animals and humans. The objective of this study was to determine Ni, Mn and Cd distribution in soil and crops shoots around the Mobarakeh Steel Plant. In this study, we separated 50 zones based on soil utility maps taking into consideration the dominant wind direction (south-western to north- eastern). In each zone, soil was sampled at 0-5, 5-10, 10-20 and 20-40 cm depths (200 samples) and DTPA-extractable concentrations of Ni, Mn and Cd were determined in soil samples. Also 36 plant samples from shoots of 18 main crops were collected in the region and the concentrations of heavy metals were determined in crop samples. Results showed that maximum DTPA-extractable concentrations of Ni and Mn were in the northeast of the region in the 0-5 cm layer (4.2 and 312 mg/kg. soil, respectively) and decreased in 5-10,10-20 and 20-40 cm layers (2.7, 2.7, 2.1 and 200, 212, 146 mg/kg. soil, respectively). The concentrations of Ni and Cd in shoots of crops were undetectable with atomic absorption method. The concentration of Mn in rice shoots was 716.6 mg/kg.dry.m. It was higher than USEPA standards (15-100 mg/kg.dry.m).

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.

Information about nonexchangeable potassium (NEK) release rate in Hamadan soils is limited. The objective of this study included an investigation of the dynamics of NEK in some soils from Hamadan Province by successive extraction with dilute citric acid over a period of 2500 h and determination of the correlation between the rate constants in this kinetic equation with soil properties.The results of this experiment showed that the initial NEK release rate was rapid which slowed down later on. The amount of NEK released after 2500 h ranged from 0.87 to 2.89 cmol kg-1. The amount of NEK released after 2500 h was significantly correlated with CEC, NEK, and soil separates. First order, parabolic diffusion law and power function equations described well the NEK release kinetics based on their highest determination coefficient and their lowest value of the standard error of the estimate. Release rate constant in the first order, parabolic diffusion law and power function equations ranged from 1.0×10-4 to 3.0×10-4, 1.7×10-4 to 10.6×10-4 and 2.75×10-1 to 4.6×10-1, respectively. In the correlation study the rate constants in the kinetic equations were correlated with some chemical properties and particle size distribution. The results of this experiment also showed that dilute citric acid can be used in the study of NEK release.

Although safflower is known to be a cool-season crop, it is usually planted as a summer crop in Isfahan. Thus, an experiment was conducted in 2000 at the Agricultural Research Station, Isfahan University of Technology, to study the effects of date of planting on growth, yield components, and seed yield of safflower. Five planting dates (March 12, April 12, May 10, June 8, and July 12) and four safflower genotypes (Arak 2811, local variety Koseh, Nebraska 10, and Veramin 295) were evaluated using a randomized complete block design with split-plot layout in three replications. Date of planting was considered as the main plot and cultivars were randomized in sub-plots.Delay in planting from March 12 to may 10 reduced plant dry weight per unit area, number of heads per plant, number of seeds per head, seed yield per unit area, harvest index and petal yield. The above traits increased as planting was further delayed from May 10 to June 8. Highest seed oil and lowest seed protein contents were also obtained for this planting date. Plants of July 12 planting date did not reach physiological maturity. Among the genotypes evaluated and over planting dates, the highest and lowest number of heads per plant, 1000-seed weight, and seed yield were produced by Arak 2811 and Veramin 295 (mean of the first and second planting dates), respectively. Highest seed yield (4512 kg ha-1) was produced by local variety Koseh in June 8 planting date. It might be concluded that this variety has adapted to the summer planting conditions of Isfahan by natural selection.

The aim of this research was to study the effect of treatment with oyster mushroom (Pleurotus sajor-caju) on digestibility of Glycyrrhiza glabra L. pulp. Pleurotus sajor-caju was inoculated on sterilized wheat grains. Two weeks after growth at 25°C it was added to the sterilized Glycyrrhiza glabra L. pulp in nylon bags. After two weeks (at 25oC), mycelia grew on the pulp and were used for treatment. Digestibility coefficients were measured in 12 Ghezel rams.Dry matter, crude protein (CP) and nitrogen free extract (NFE) increased, but ash content, cell wall (NDF) and lignin (ADL) decreased significantly in fungal-treated as compared with non-treated pulps. Crude fiber (CF) and ADF contents were not significantly affected by the treatment. There was a tendency for crude fat (EE; ether extract) to decrease by fungal treatment (p=0.08). Mean dry matter intake and digestibility coefficient of dry matter were higher in sheep which were fed the fungal-treated pulp compared with the control group. Digestibility coefficients of CP, CF, organic matter (OM), EE, NFE, NDF, ADF and ADL were significantly greater in fungal-treated pulp than in control group. Treatment with P. sajor-caju increased the nutritive value and digestibility of Glycyrrhiza glabra L. pulp (P<0.05), but culture of this fungus was not possible on non-sterilized pulp, which hinders its field application.

This experiment was conducted to evaluate the effects of adding acetic acid to drinking water on the performance and ileal microorganisms of broiler chickens. In a completely randomized design with 5 treatments and 5 replicates, 300 day-old commercial mail broiler chicks (ROSS) were divided into 25 groups, 12 chicks per group. Each of the five levels of acetic acid added to drinking water (0.0, 0.1, 0.2, 0.3, and 0.4%) were given to five replicates for a period of 21 days. All groups were fed a practical corn-soybean based diet. During the experiment, chickens were not fed any antibiotics or coccidiostats. The diet formulation for all groups was the same. At 14 and 28 days of age, one chicken of each replicate was weighed and killed by cervical dislocation. Ileal contents were collected and used for microbial evaluation. At 49 days of age, one bird from each pen was killed to weigh gastrointestinal tract, liver, pancreas and abdominal fat. The number of total aerobes and colliforms per gram of ileal contents were enumerated on the appropriate bacteriological media. There was no significant difference in feed intake, weight gain, feed to gain ratio, live body weight, gastrointestinal tract, abdominal fat, liver and pancreas weights (p>0.05). Also, the differences among treatments for total aerobe and coliform counts were not significant (p>0.05). Under the conditions of this study, addition of acetic acid as an organic acid into drinking water at the levels used could not affect the performance and ileal microbial counts of chickens.

In a completely randomized design, the effects of six different additive compounds including limestone, hydrochloric acid, zeolite, aluminum sulfate, pad ammoniac, and fatty acids on nitrogen, pH, temperature, moisture, water soluble phosphorus, and microbial count of litter of broiler chicken were investigated. Each compound was added at a level of one kg/m2 of litter. Six–hundred-and-sixteen (616) day- old broiler chickens (both sexes) were divided into 28 groups, 22 chicks per group. Four replications were allocated to each treatment from 1 to 56 days. All groups were fed with the same diet.Litter moisture was not affected by the treatment. Experimental treatments significantly (p<0.05) influenced the litter pH on day 21. The lowest pH was obtained with aluminum sulfate and the highest pH was obtained with limestone. At the end of the experimental period, all treatments had nearly the same pH levels. Litter temperature was not affected by the treatments. Experimental treatments had a significant (p<0.05) effect on litter nitrogen and bacterial count. Correlation between litter pH and nitrogen was significant and negative (r=-0.95, p<0.05). Effect of treatments on soluble P was significant and the lowest soluble P belonged to aluminum sulfate and pad ammoniac. Correlation between soluble P and pH was positive (r=0.48, p<0.05). The results showed that some chemical compounds can be used to reduce litter pH, nitrogen, and soluble P and their effectiveness diminishes as chicks grow older.

Low calorie salad dressings are oil-in-water emulsion products, in which the oil content has been substantially decreased. This decrease, however, is accompanied by reduction in the viscosity; hence, an undesirable texture. To overcome this, oil replacers are generally used. In this research, maltodextrin and xanthan gum were used to replace part of the oil in the production of two kinds of salad dressings; mayonnaise and three Italian salad dressing. Various formulations of these products with varying amounts of oil, maltodextrin and gum at different temperatures were produced. Viscosities in the range of 50-140 Pa.s for mayonnaise and 2-15 Pa.s for Italian dressing were accepted as positive criteria and samples in these ranges were chosen for organoleptic and microbial tests.The results showed that in the formulation of mayonnaise, simultaneous increase in the amount of oil, maltodextrin and gum created a high viscosity, but the temperature did not play any significant role. In the Italian salad dressing, the increase in the amount of gum was accompanied by development of pseudoplastic characteristics which was not desirable, hawever, the effect of temperature on providing acceptable texture was found to be important. Although the formulated mayonnaise enjoyed a fairly acceptable quality, the Italian salad dressing samples, were ranked superior to the common Italian salad dressing available in the Iranian market.

The black dot disease of potato is a fungal disease caused by Colletotrichum coccodes (syn. C. atramentarium) that produces accervuli on infected underground plant parts which appear as black dots. The disease appears at the flowering stage and develops up to the season end. The survey on black dot disease of potato in two successive years indicated that the infection percentage is 39.86 in Feraydan (Isfahan), one of the most important potato production regions in Iran. Studies on usual cropping patterns with, potato including, wheat alfa-alfa, barley and fallow showed that in terms of disease infection, one year rotation with fallow reduced the disease severity almost to half compared with control and other cropping patterns. Biological seed and soil treatment, with Trichoderma harzianum in various spores density reduced the disease in various degrees significantly and increased the potato plant growth factors including the number of stems, foliage fresh and dry weights, and also the yields in cases of spore applications, depending upon the type and application dosage. Comparative susceptibility assessments of 24 commercial potato varieties to the black dot disease indicated that the variety Desiree was the least concerned in terms of infection, followed by Scort ,Casser, Casmos, Carlita and Moren , where as Marijke, Cosima and Monalisa were highly infected in comparison to other tested verities and the rests of varieti es were scored within these two ranges.

Elm leaf beetle, Xanthogaleruca luteola (Müller), life and fertility tables were investigated under laboratory conditions (25±2oC, 70±5%R.H. and 16L: 8D), on Ulmus carpinifolia, U.c.var.umbraculifera, U. glabra var. pendula and Celtis caucasica, in spring and summer. Since the experiments were conducted under controlled conditions, feeding on hosts with different nutritional qualities was considered to be the only cause of mortality. The aim of this study was to determine the susceptible hosts to the pest. The initial population for each life table was 100 first larval instar on 20 cm foliage which continued to the end of adult longevity. For larval and adult feeding, the foliage was replaced regularly. Larval and adult mortality and eggs number per female were recorded on a daily basis.Results showed that the net reproductive rate (R0) and intrinsic rate of increase (rm) were higher on U. carpinifolia than the other hosts in both seasons. The net reproductive rate was less than one on Celtis caucasica in spring and on U. c. var. umbraculifera in summer, which represented the negative population growth on these hosts. Therefore, U. carpinifolia was the most susceptible host to Elm leaf beetle, the other susceptible hosts being U. glabra var. pendula and U. c. var. umbraculifera, in a descending order and Celtis caucasica was the least susceptible one.

Safflower (Carthamus tinctorius L.) is one of the multi-purpose oilseed crops which has a high adaptation to different conditions such as resistance to drought and it is suited to be grown in arid and semi-arid regions such as Isfahan province. Root rot disease is an important soil-borne disease of safflower in Isfahan, which can be caused by different pathogens. The objective of this study was to determine the causal agent of safflower root rot and to evaluate different genotypes for tolerance to the disease. Different species of Fusarium were isolated from sample collections. Laboratory and greenhouse inoculations indicated that F. solani was the only pathogenic species. In this experiment, 60 genotypes of safflower including breeding lines selected from various Iranian local populations and foreign cultivars were evaluated for reaction to the disease in a randomized complete block design with three replications in greenhouse. Artificial inoculation via injection of spore suspension of F. solani (106 spores/ml) was conducted on 8-week plants and then development of necrosis and death percentage were recorded. The results showed that there were significant differences among the genotypes in terms of reaction to the disease. The most resistant and susceptible genotypes were breeding lines of IUTE14310 and  IUTC121 with mean necrosis of 9.67 and 28.33 mm, and death percentage of 32 and 74, respectively. Based on the means of necrosis and death percentage, the genotypes were significantly classified in 5 distinct groups including resistant (7 genotypes), moderately resistant (19 genotypes), tolerant (29 genotypes), moderately susceptible (3 genotypes), and susceptible (2 genotypes). The commercial foreign cultivars of AC Sunset, AC Sterling belonged to tolerant and moderately susceptible groups, respectively. However, Saffire was classified as a tolerant genotype. The local landrace of Kooseh which is widely grown in Isfahan province was classified as susceptible genotype. Phenotypic and genetic coefficients of variation (23.85 and 18.32%, respectively) and a relatively high broad-sense heritability (59%) for necrosis and also the phenotypic and genetic coefficients of variation (25 and 21%, respectively) and a high broad-sense heritability (73%) for death plants indicated that there was sufficient genetic variation for resistance and selection can be effective for producing resistant genotypes to Fusarium root rot disease.

Distribution of Phytophthora species associated with stone fruits decline in Fars was investigated. Of 36 isolates of Phytophthora recovered, 23 were identified as P. cactorum (mostly from infected crown) from almond, apricot, and peach and 13 isolates of P. nicorianae from crown and basal stem of almond and apricot from different environmental conditions. The reactions of crown and root of 6- month–old local almond cultivars, i. e., Mamaee, Moheb-Ali, Talkheh e- Najafabad (Isfahan Province), Talkheh Sadeh, and Sang Talkheh Riz from Neiriz (Fars Province), peach cultivar bitter pit and apricot cultivar Hallander from Isfahan to a virulent isolate of P. cactorum were evaluated under greenhouse conditions. The inoculum of the pathogen was obtained by growing on vermiculate – hemp seed extract for 4-6 weeks and positioned around either crown or root system. Plant height, root and total weight of plants, lesion size, plant mortality, and percentage colinization of the pathogen on root and stem base were determined.The results indicated that almond cv. Mamaee was the most susceptible and almond cv. Talkheh-e-Najfabad, peach cv. bitter pit and apricot cv. Hallander were the most resistant rootstocks to P.cactorum. Comparative reactions of root and crown of various rootstocks to P. cactorum showed that although inoculation site (root or crown) in most cultivars was not significant to most characters measured, the interaction of cultivars ´ site of inoculation became significant for certain characters such as plant height, lesion size, root and total plant weight and mortality, indicating different reactions by root and crown to P. cactorum in some cultivars.