نشریه علوم آب و خاک (علوم و فنون کشاورزی و منابع طبیعی)
سال هفتم شماره 1 (پیاپی 23، بهار 1382)

Numerous methods are used in the investigation of floods in catchments such as regional flood frequency analysis. Regional flood frequency analysis relies on physical, climatic and ecological characteristics of catchments and applies statistical methods to study flow records. Hosking and Wallis developed Probability Weighted Moments and presented L-moments statistics as a new tool for flood frequency analysis. In this paper, the theory of L-moments was used to study the flood frequency of central catchments of Iran. A number of 27 sites each with more than 5 years of observed data were studied. In the first step, the diagram of L-kurtosis versus L-skewness was used and proper distributions for each site were applied. In order to eliminate the heterogeneous sites, homogeneous tests based on D, H1, H2 and H3 criteria were performed indicating that two sites appeared to be heterogenous. Next, using Goodness of Fit Test, the best regional distributions were determined which are GL, GEV, GN, PE3 and GPA, respectively. Finally, quantile estimates for distributions accepted at a 90% level were presented.

In this study, two data ranges of uniform flow (bulk parameters) and non-uniform flow (local parameters) are employed to investigate resistance to flow and the factors affecting it using velocity distribution of boundary layer theory. The results indicate that the cross-section form factor or adjustment roughness coefficient of logarithmic law can not improve the prediction of flow resistance. On the other hand, it is possible to ameliorate the prediction of resistance to flow by application of the Froude number and the Shields parameter along with the integration constant of the logarithmic velocity distribution. Also, there is no improvement in flow resistance prediction by taking into account power equations. On the other hand, the application of boundary-layer characteristics such as displacement thickness and momentum thickness in velocity profile can remove the risk of spurious correlation. Based on the measured velocity profiles for non-uniform flow in Gamasiab river, a new flow resistance equation is suggested in which the following bulk parameters are considered: flow depth, maximal velocity at the water surface, and friction slope.

Point data of weather stations are not important in and by themselves. Therefore, it is necessary to change these point data into regional information. Undesirable distribution of weather stations and their data deficiency hinder the direct determination of the regional information, unless sufficient data in the study area could be provided. Providing extra data using the geostatistical methods is practical, scientific, simple and quick, but adopting a suitable method is the basic question. The objective of the present study is to find a suitable method to estimate monthly rainfall in the central region of Iran. In this regard, the methods of kriging (ordinary kriging, log-kriging, co-kriging), weighted moving average (WMA, with the power of 1 to 5), thin plate smoothing splines (TPSS, with the power of 2 and 3 and with covariable) were used. Cross validation technique was used to compare these methods. Based on the variography analysis, the range of influence of monthly rainfall in the central region is about 450 km. The results show that TPSS, with the power of 2 and with elevation as a covariable, was the most accurate method to estimate monthly rainfall. In addition, it is preferable to use the selected interpolation method in the sub-basins with homogeneous climates instead of considering the whole region.

Increasing application of herbicides such as atrazine raises concerns about soil and groundwater pollution. This study investigated spatial and temporal variation of atrazine concentration and its transportation in the Daneshkadeh soil series (Fine, mixed, mesic, Calcixerollic Xerochrepts) at the experimental field of Agricultural College, Shiraz University. The risk of soil and water contamination due to applying atrazine was also assessed. The PRZM-2 model was evaluated for the simulation of the atrazine concentration. The experiment had 3 plots, 209 m2 each (19 by 11 m). Atrazine was applied on corn at a rate of 3.5 kg a.i./ha per plot. During the growing season, soil samples were collected from each plot 7 times through 1 m soil depth with 0.10-m increments. The observed data showed temporal reduction of atrazine concentrations in the soil profile. The maximum depth of atrazine traced was about 50 cm below the soil surface. Statistical parameters ME, RMSE, EF, and CRM were obtained to compare PRZM-2 predicted and observed soil residue concentrations. For all data, the mentioned parameters were calculated and found to be 2.78 mg/kg-soil, 12.73 mg/kg-soil, 0.49, and 0.25, respectively. The simulation results were in close agreement with the observed data. Therefore, PRZM-2 could be used for simulation of atrazine transport and groundwater pollution.

The study of geographical extent of precipitation pattern is important because of its impact on agriculture, water resources, tourism, industry, dams, and irrigation. The principal component analysis (PCA), as an elegant mathematical tool, was applied for the regionalization of winter precipitation in central south Iran (Fars, Boushehr, and Kohgiloye and Boyerahmad Provinces). Averaging monthly rainfall data of Dey, Bahman and Esfand (20 December to 20 March) produced the time series of winter rainfall. In each individual station, correlation matrix of the normalized data was then performed for the computation of the standard PCA. Eigenvalues, eigenvectors, PC time series and the loading of the principal components were then computed. The Screet test technique was applied as a trial for addressing the problem of determining the number of PC modes that should be retained. Two of the first PCs, which account for 68.1% of total variance in the rainfall data, were kept and used for the regionalization of rainfall data. The rotation solution was then selected as a suitable tool for delineating the rainfall region associated with the retained PCs. The results indicated that for the first PC, loading became high over most part of the study area. Therefore, the time series of PC1 that accounts for about 60.4% of the variance in raw data, could be used as the regional time series of winter rainfall over most parts of the provinces studied. The second PC revealed a high loading over a small area in northern part of the regions studied (Bavanat in Fars Province). Rainfall in this station showed poor correlation with the precipitation over the neighboring station in Fars Province. It seems that the rainfall in Bavanat is mostly influenced by the Mediterranean air masses entering the area through the northern and western districts. For the other parts of the regions studied, Sudan current which encroaches the country through southwestern borders (Persian Gulf regions) make up an essential portion of winter rainfall.

Clay minerals have considerable effects on physico-chemical properties of soils. Using different techniques, mineralogy of silicate clays and their formation were investigated in selected soils from Chaharmahal and Bakhtiari Province. The study area is about 1300 ha and its soil moisture and temperature regimes are xeric and mesic, respectively. Geomorphologically, the area consists of different landforms including pediments, outwash, hills and piedmont plain. After field and laboratory studies, five representative pedons were selected in previously determined mapping units and samples were taken for the analyses required. Clay particles from two surrounding rock formations and selected soil samples were separated and examined by electron microscopy (SEM and TEM), X-ray diffraction and infrared techniques. Illite, smectite, chlorite, palygorskite and kaolinite were present in all the soils. Considering the fact that palygorskite was not observed in nearby rock formations, this mineral is probably formed by pedogenic processes. Smectite, on the other hand, has been inherited from parent materials and also transformed from palygorskite. Other minerals had been probably inherited from parent materials. Infrared spectra confirm the X-ray diffraction and submicroscopic results.

Soil tilth is crucial to seedling emergence, plant growth, and crop yield. Soil tilth of unstable soil is very susceptible to change. Internal forces originating from matric suction can change soil physical properties. A laboratory study was conducted on pots of a surface silty clay loam soil of Khomeinishahr series (fine-loamy, mixed, thermic Typic Haplargids, USDA), located in Research Farm of Isfahan University of Technology. Soil surface subsidence, bulk density, cone index, and tensile strength were measured after first flood irrigation. Results showed that the seedbed (0-20 cm) with a bulk density of 1.2 Mg.m-3 will be changed to a massive soil with high values of bulk density, cone index, and tensile strength after soil wetting. Slaking, slumping and coalescence of the soil caused soil surface to subside about 1.5 cm in 20 cm soil layer. After irrigation, cone index and tensile strength increased abruptly with decreasing of moisture content. It is shown that the dominant source of strength (cone index and tensile strength) gain during drying is the effective stress due to matric suction. In the absence of external loads, physical state (tilth) of the soil returned back to the original state. Therefore, soil slaking and slumping and rearrangement of particles along with the internal forces are the factors leading to soil hardness.

Thirty genotypes of pistachio cultivars and related species were evaluated for genetic diversity using three polymorphic isozymes, i.e. Esterase, Peroxidase and Malate dehydrogenase. Young leaves of pistachio were crushed with extraction buffer containing: 20% sucrose, 0.01 M dithiothretiol, 2% polyethylene glycol, and 8% polyvenyl polypyrollidone. Samples were analyzed using isoelectric focussing on polyacrylamide gels containing 2% (W/V) ampholyte. All the three isozymes revealed high degrees of polymorphism in pistachio cultivars and related species. Maximum polymorphism was observed for Est. enzyme. A total of 19 bands in Est. and 28 bands in MDH were observed in a wide range of pH gradient however, in Per. there were 11 bands all of which located in a narrow range of pH gradient. Cluster analysis based on the three system enzymes revealed that all the 30 pistachio genotypes were in 8 main classes and 20 subclasses and the extent of genetic similarity reduced from cultivated varieties to species, which were finally classified in 3 groups. Sarakhs variety, a wild type of P. vera, was classified in a group between cultivated varieties and species.

Genetic variation of 300 genotypes of durum wheat comprising CIMMYT/ICARDA and Iranian germplasm was evaluated in 1999-2000 at Researh Farm of College of Agriculture, Isfahan University of Technology located at Lavark, NaJaf-Abad. Days to heading, days to maturity, plant height, spike length, grain weight per spike, number of grain per spike, number of spikes per m2, 1000-grain weight, test weight, grain yield, biological yield, and harvest index were recorded. Coefficients of correlation, step-wise regression, factor analysis and cluster analysis of characters and genotypes were conducted using the studied traits. Results indicated that considerable genetic variations exist for the traits and, in particular for grain yield, harvest index, number of spikes per unit area and number of grain per spike. Grain yield had a positive and significant correlation with days to heading, days to maturity, number of grain per spike and grain weight per spike. Factor analysis for the genotypes detected 6 factors, which explained 76.7 percent of the total variation among data. These factors basically involved potential of assimilate distribution, different aspects of plant storage, source-sink relationships, plant height and tillering potential. Cluster analysis was similar to factor analysis in grouping the characters. According to cluster analysis, the genotypes were calssified into 6 clusters with significant differences among all groups. Mean comparisons of traits in these groups showed that genotypes of groups 5 and 6 were superior in grain yield and harvest index and are beneficial to the local durum breeding objectives.

Planting density, through its impact on the level of available environmental factors may have significant impacts on grain yield in safflower (Carthamus tinctorius L.). In order to investigate the impacts of plant density on grain yield, yield components and growth characteristics of safflower, a randomized complete block design field experiment with four replicates was conducted in spring-summer, 2000, at Lavark Research Farm (Lat. 320 32, N and Long. 510 23, E), College of Agriculture, Isfahan University of Technology, Isfahan, Iran. Arak-2811 and Kouseh safflower genotypes were seeded at 16.6, 22.2, 33.3 and 50 plants/m2. For establishing these plant densities, plants were seeded in 12, 9, 6 and 4 cm distances, respectively, on ten 8-m-long rows spaced 50 cm apart in each plot. Plant density had no impact on plant growth stages with the exception of button formation. Genotype had significant effects on days to seedling emergence, button formation, and 50% flowering. While both number of days and accumulated growing degree-days for all growth stages decreased with an increase in plant density, Arak-2811 was earlier than Kouseh for most growth stages. Number of branches and heads per plant, number of heads per branch, number of seeds per head and harvest index showed significant decreases with increasing plant density. The decrease in the mentioned grain yield attributes was mainly negated by greater number of plants per m2, leading to no significant variation in grain yield between plant densities of the two genotypes. Arak-2811 produced a significantly greater number of heads per branch and 1000-grain weight however, these differences did not lead to any greater grain yield compared to Kousehdue, mainly due to the greater number of branches in the latter. Neither of the leaf area index, leaf area duration, and crop growth rate varied significantly with plant density and between two genotypes, suggesting no difference in dry matter production capabilities of the two genotypes under environmental conditions of the present study.

Flax (Linum usitatissimum L.), an oilseed crop, is widely adapted and grown in many regions of the world. Oil from regular flaxseed is used as an industrial drying oil because of the high level of linolenic acid (>50 %). However, the oils from new mutant genotypes of flax with a very low linolenic acid concentration (<2 %) are edible. Yellow seed colour can be used as a visual marker to distinguish edible-oil genotypes of flax from those of industrial type that are usually brown-seeded. In this study, different lines of flax with two seed colours (yellow and brown) in combination with two levels of linolenic acid (high and low) were evaluated in a randomized complete block design for agronomic traits, especially seed yield and its components. The results indicated that lines with high linolenic acid concentration had significantly higher seed yield than those with low linolenic acid. However, other characteristics including those of seed yield components were not siginficantly affected by linolenic acid concentration. Seed colour had a significant effect on number of seedling/m2, basal branches, capsules per plant and seed yield per plant. Although seedling emergence was lower in yellow-seeded lines, they had more basal branches, capsules per plant and seed yield per plant. Higher seed yield per plant in yellow-seeded lines can be attributed to higher number of capsules per plant as a result of lower seedling emergence and plant density. Seed yield was not significantly different between brown and yellow-seeded lines. Thus, the effect of lower plant density in yellow-seeded lines was compensated by their higher basal branches and number of capsules per plant.

Planting pattern through changing vegetative growth and utilization of environmental resourses affects yield components and seed yield. These effects were studied in the spring of 2000 at the Agricultural Research Station, Isfahan University of Technology, using a randomized complete block design with a split plot layout and three replications. Main plots consisted of three row distances (30 cm flat, and 45 and 60 cm on bed), and sub-plots included three planting densities (30, 40, and 50 plants m-2). The experiment was planted on March 13 using local safflower variety of Isfahan, named Koseh. Increase in row distance and plant density enhanced most developmental stages of safflower. Leaf area index was not significantly affected by row distance but increased as planting density increased. Up to the 50% flowering stage, 30 cm row distance produced highest plant dry weight, but had the least dry weight at the end of the growing season, probably due to the strong shedding of leaves. Up to the end of flowering stage, 50 plants m-2 treatment produced the highest plant dry weight, but ranked lower as compared to 30 plants m-2 treatment at the physiological maturity, probably due to the shedding of leaves. Row distance had no significant effect on number of branches per plant and per square meter, number of heads per branch, number of seeds per head, 1000-seed weight and harvest index. But number of heads per plant and per square meter as well as seed yield per plant and per square meter significantly decreased as planting distance increased. Plant density had no significant effect on number of branches per plant, number of heads per square meter, number of seeds per head, 1000-seed weight and seed yield. Increase in planting density increased number of branches per square meter, but reduced number of heads per branch and per plant, seed yield per plant and harvest index. The highest seed yield (4769 kg ha-1) was obtained with 30 cm row distance and 40 plants m-2 treatment. On average, 397 kg ha-1 petal was harvested, which has a large economic value. However, petal clipping, over all treatments, reduced seed yield by about 7.4%. Considering the advantages of uniform distribution of plants and adaptation of safflower to flat planting, 30 cm row distance with 40 plants m-2 might be appropriate for planting safflower under conditions similar to this experiment.

A ruminal in situ experiment using three fistulated ewes was conducted to determine dry matter (DM) and crude protein (CP) degradation of steam–flaked broomcorn (SFBr), ground broomcorn (GBr) and ground barley (GB). Grain samples were suspended in the rumen of sheep for 0, 2, 4, 8, 16, 24 and 48 h. Nylon bags were washed with tap water after removal. Effective degradability of DM at outflow rates of k = 0.05 and k = 0.08 h-1 was significantly higher for SFBr than for GBr (59 and 53% vs. 43 and 35%). SFBr has considerably higher soluble DM than GBr and GB. Insoluble DM of SFBr was lower than that of GBr and GB. Solubility of CP in broomcorn grain was significantly decreased by steam–flaking, but degradation rate of insoluble CP was not altered. Results from this study showed that SFBr supplies the major source of availabe nutrients for rumen microorganisms compared with GBr. In other words, using the most efficient processing method for ruminants will be necessary.

Whey powder, due to its lactose and protein contents, can be used as an important flour improver to decrease the rate of staling. In the present investigation, whey powder was added at 5 levels (zero to 5%, W/W) to the flour of Sangak bread. Bread was baked according to the formula and procedure used by traditional Sangak bakeries. Bread samples were kept at room temperature or under refrigeration for 36 hours. They were then evaluated for staling by a taste panel. They were also subjected to proximate analysis. The dough was examined for farinographic, amylographic, extensographic and fermentographic properties. The data of staling tests including color, texture, flavor and also proximate analysis data were analyzed by ANOVA. Finally, differences among treatments were examined by Ducan’s multiple range procedure. The results indicated that the best treatment was the use of 3% whey powder, as far as staling and texture of bread are concerned. However, the best color of bread was achieved with 5% whey powder so was true of the protein, ash and fat contents. Viscosity, as tested by amylography, and also parameters of farinography reached their highest levels in the dough prepared from flour having 5% whey powder in the formula. The best extensibility was observed with the flours containing 4% whey powder and the highest dough energy was associated with the dough prepared from flour having 5% whey powder. As for the loaf volume, best results were obtained with the dough prepared from flour having 3% whey powder. Overall, it is concluded that the use of 3% whey powder is the best treatment with regard to the delay in the rate of staling, increase in loaf volume, and color appeal of Sangak bread, and rheological properties of the dough.

Dehydration of Mazafati Rutab is a method to prevent its spoilage. Dehydration is necessary for Mazafati Rutab because it contains too much moisture. If the moisture content of Mazafati Rutab is decreased properly, it need not be stored under refrigeration. The present study was carried out in an attempt to decrease the moisture content in order to increase the shelf life of Mazafati dates. Samples were dehydrated in a drying room at different drying times and 50-55 oC. The moisture content and quality characteristics of Mazafati dates such as acidity and sensory evaluation (texture, flavour and overall acceptability) were determined at 3-hour intervals and also drying curve of the fruit was drawn. Relative humidity in the drying room was 10-15%. During the drying process, the acidity content gradually increased due to the activity of microorganisms but organoleptic properties decreased especially affer 12 hours of drying time and at moisture levels less than 22%. Finally, drying time of 9-12 hours and acceptable moisture content of 22% were recommended. Dates with over 22% moisture levels are an easy target for microbial attack but the desirable quality of the fruit decreases at moisture levels below 22%.

In order to compare Pseudomonas syringae pv. syringae (Pss) isolates from cereals, citrus, stone fruits and weeds by phenotypic characteristics, serological properties and pathogenicity, samples were taken during 1998-1999 in Fars Province, Karaj, Fereidan, Aligudarz and Shahrekord regions. From 350 fluorescent isolates, 47 were negative with respect to oxidase, potato soft rot and arginine dihydrolase tests but positive in hypersensitive reaction (HR) on tobacco, pelargonium, or both. In complementary biochemical tests, these isolates were identified as Pss. Based on LOPAT (levan, oxidase, potato soft rot, arginine dihydrolase and HR on tobacco leaves) tests, the isolates were divided into two groups, but based on the results of GATTa tests alone, isolates were divided into nine groups. Isolates from different hosts showed differences in lipolysis, syringomycin production, ice nucleation activity, lecithinase, pathogenicity, serology and protein profiles.

In this study, susceptibility of the first three larval stages of Spodoptera exigua to Bacillus thuringiensis was investigated. To determine the LC50 values for each larval instar, 6 different logarithmic concentrations of Bacillus thuringiensis were used. A control was also included in each of the bioassays. The value of LC50 for 1st instar larvae, that had been treated one to four hours after hatching, was 311.617 ppm. For the 2nd and third instars, the larvae values of LC50 were 1356.95 and 2708.27 ppm, respectively. It was clear that larval susceptibility to Bacillus thuringiensis decreased with age. In order to enhance the Bacillus thuringiensis efficiency to control Spodoptera exigua under field conditions, Bacillus thuringiensis should be applied at egg hatch peaks.

High attraction is reported for yellow sticky traps to capture pistachio psylla. In pest management, it is important to forecast from the adult population density the density of other developmental stages in order to gain an estimate of the density in damaging stages. In 1998 and 1999, yellow sticky boards with 10150.15 cm were installed in two pistachio orchards in Borkhar district of Isfahan and egg and nymphal densities were simultaneously counted on leaves. Collected data were used to determine regression relationships between two weeks’ average egg density, first and second nymphal instar densities and the sum of egg and first and second instar nymphal densities, one week after the average adult capture in two previous weeks. A low correlation was found between egg count and adult capture, but higher coefficients were obtained between other stages. It was possible to estimate first and second instar nymphal populations from the following equations: For high adult densities (X): Y= 58.6+0.4762X-(7*10-5)X2 R2=0.82 commercial orchard Y= 27.68+0.5092X-(5*10-5)X2 R2=0.86 abandoned orchard and for low adult densities (X) Y= 1.7162X-17.454 R2=0.97 commercial orchard Y= 1.1117X-4.9841 R2=0.90 abandoned orchard The application of this method is recommended for the management of pistachio psylla.

In order to investigate the effects of mineral compounds as complementary nutrients for silkworm, Bombyx mori, an experiment was performed in CRD with five treatments including: 1%, 5% and10% concentrations of multi-mineral mixtures (nitrogen, phosphorus and potassium) with normal and distilled water treatments as controls. The larvae were fed by mulberry leaves from Shien Ichenoise variety up to the fourth instar. From the beginning of the fourth instar, the supplementary leaves were used once a day. The supplementation of the leaves was done by spraying the solution on them. The amount of total protein and uric acid in haemolymph of a 6-day 5th instar larva was measured. The value of total protein compared to controls had significantly increased in all mineral treatments. The larvae's weight on the third day of the fifth instar had significant difference from controls, but the weight of silk gland did not show such a difference. However, uric acid of insect's blood demonstrated little differences but it showed no statistical significant differences from that in controlled insects. Despite this, the weight of cocoon, cocoon shell and pupa also had significant differences compared to controls, where this enhancement was higher in females than in males. Due to increase of the number of eggs, statistically there was a significant difference between the 10% treatment and others. The compounds had decreased the hatching percentage.

The present experiment evaluated the effects of fat (Kilka fish oil) levels (0, 5, 10, 15 and 20%) in the diet (35% constant protein) on performance of rainbow trout. The experiment was performed in a completely randomized design, with 4 replicates, 200 grower fish with an average weight of 200±11 gr, each. They were randomly divided into 20 groups of 10 fish per group reared in separate pens. Fish were acclimated to the experimental conditions for 10 days before treatments began and then the experiment was performed over a period of 8 weeks. Measured criteria were weight gain (WG), specific growth rate (SGR), feed conversion ratio (FCR), condition factor (CF) and flesh chemical composition (fat, protein, ash), and fat stored in liver. Results showed that the diet with 15 percent fat content had significantly (P<0.05) better WG and FCR than other diets, but no significant differences were observed for SGR and CF. Diets with 15 and 20 percent fat contents caused the highest fat content in meat and liver and showed significant differences (P<0.05) with the meat and liver fat content in fish fed fat-free diets. Diet with 15 percent fat content caused significantly (P<0.05) lowest protein content in meat. No significant differences were observed in the ash content of the flesh. From the results of the present study, the level of 15 percent Kilka fish oil is recommended for the rainbow trout diet.