Journal of Agricultural Sciences and Natural Resources
Year:2005 | Volume:12 | Issue:3|Papers Count:20

The saturated hydraulic conductivity K and the effective porosity f are the most important parameters needed for lateral spacing drainage design. Economic and technical justification of most of drainage engineering projects is mainly based on the mentioned parameters. In this research, Glover Dumm, Kumar et al., Sing et al., Upadhaya et al., and Tapp and Moody unsteady analytical models within the context of the inverse problem method, a technique which is widely used in engineering recently, have been incorporated. Based on the results, each model has been evaluated. The proposed method is based upon measuring water table profiles at different times. Different data sets from the conducted experiments and literature were used for calibration and verification. The results showed that the inverse problem method is a strong tool to be used for the above purposes. With variable effective porosity compared to the constant ones, the models are even much more successful to predict water table profiles. Finally, in all the investigated cases, Tapp and Moody model showed better results than the others.

To illustrate the impacts of deficit irrigation on yield and some agronomic characteristics of wheat, a study was conducted based on randomized complete blocks as a split plot design with 3 replicates and 3 treatments for 2 years. Three levels of irrigation water including: 60, 80 and 100% of irrigation water requirement (IWR) were considered as main plots and 6 varieties as subplots in an experimental site located in Kabutarabad Agricultural Research Station. Results showed that irrigation treatments had significant effect on grain yield, 1000 kernels weight biological yield, number of grain in spiker and plant height (p<0.0 1). However, the numbers of spike per m2 and harvest index were not affected significantly. Significant differences (P<0.01) were noticed in grain yield, plant height, biological yield, number of grain in spike and 1000 kernels weight among the cultivars. However, the effects on the aforementioned indices were not significant. Maximum WUE was noticed in the 60% IWR, equally to 1.433 Kg/m3. Tolerance to water stress (in a descending order) was found in M-73-18, Pishtaz, and Backcross Roshan, respectively. Hence, The 60% IWR is recommended for the arid and semi-arid regions.

In this research an Artificial Neural Network (ANN), with multilayer perception structure, was adapted to model conjugate depth and gradually expanding jump length, which are especial but complex cases of hydraulic jumps. More than 3000 interpolated and experimental data on conjugate depths and jump lengths for both normal and gradually expanding jumps were used. The data was due to rectangular and trapezoidal sections, for a wide range of divergent angles and side wall slope. In developing the ANN models, seventeen configurations, each having a different number of hidden layers and/or neurons, were investigated. The optimal models were capable of predicting conjugate depth and jump length for a wide range of conditions. In each case, the configuration attained highest R2 value was selected as the optimal model. For rectangular sections, the simplest ANN model had a 2-2-1 configuration, with one neuron in each of the two hidden layers, and R2=0.97 (for normal x section), and had a 4-1-1 configuration, with nine neurons in the hidden layer and R2=0.91 (for gradually expanding x-section), respectively. The best ANN model for predicting respective jump lengths had 3-2-1 and 4-1-1 configurations with one and three neurons) in hidden layer(s), and R2= 0.99 and 0.94, respectively. For trapezoidal sections, the simplest ANN model had a 4-2-1 configuration, with nine neurons in each of the hidden layers and R2=0.99 (for normal x-section), and had a 5-2-1 configuration, with six neurons in each of the two hidden layers and R2=0.94 (for gradually expanding x-section), respectively. The best ANN model for respective jump lengths had 42-1 and 5-2-1 configurations, with nine and six neurons in each of the two hidden layers, and R2=0.90 and 0.85, respectively. The high values obtained for R2 in all of the eight cases, suggest a close agreement between the Ann's output variable and the experimental data. The developed ANN models in this paper are, therefore, suitable for predicting gradually expanding hydraulic jump characteristics, which require a large amount of repetitive computations, for both rectangular and trapezoidal sections often encountered in the design of stilling basins.

The aim of the present work was to isolate and to determine the distribution of Bifidobacterium spp. in Iranian subjects. Fecal samples were collected from 90 subjects in four age groups. Bifid obacterium spp. was isolated from 70% of fecal samples. 50 strains of Bifidobacterium were isolated and characterized on the basis of morphological, biochemical and enzymatic tests. 62, 22, and 2% of the isolated strains were Blowgun, B.bifidum and B. catenulatum, respectively. 14% of the isolated strains were not resemblance with the strains which identified by now. This study showed that B. longum and B. bifidum are the commonest Bifidobacterium in the Iranian subjects. Therefore, can be suggested as proper strains to be used in bifidus probiotic products in Iran.

The harvesting time and storage conditions of olive fruit are effective factors on the quality and quantity of olive oil. The harvesting time of olive is different in each area and it depends on climatic conditions. In this study, three selected cultivars of Gorgan region include of Mission, Bleaidy and Roghani were harvested from middle September till early December with two week intervals and then quality and quantity of oil was determined. The results showed the oil content (on dry basis) for Mission reached to maximum level (44.2 %) in the middle of November and for Bleaidy and Roghani were 52.1 and 50.2 % respectively in the beginning of December. All increased oil content (as fresh % w.t) was due to decrease in water content of fruit. The acidity of oil during harvesting time arised continuously so that it was increased significantly after December. Therefore, the best harvesting time for these cultivars is beginning of December.

In this research, the most important varieties of apples, Golden Delicious, Red Delicious (open calyx) and Abbasi (closed calyx) were treated with a deep tank (6m) full of 4% calcium chloride solution. The uptake of calium into the apples were controlled by varying the depth (0, 1,2,3,4 and 5 m) to which fruits were submerged. An untreated sample was also selected as a control. After treatment, apples were stored in cold storage for 5 months with 0±1°C and 87±3% RH conditions. Some qualities and chemical properties of samples such as moisture content, pH, soluble solid, reduced sugar, calcium and firmness were studied after treatment and during the storage (1, 3 and 5 months intervals). The results showed that treated apples had lower Brix, pH, reduced sugar and higher firmness, tenderness and moisture content than control samples. Dipping in 2m (~0.2at) for Golden Delicious variety and 4m (~0.4at) for Red Delicious and Abbasi varieties reduced the physiological changes during storage, but dipping in higher depths caused skin injuries and internal breakdown.

Chilo suppressalis is a major pest in rice field of north of Iran. Beauveria bassiana was isolated from overwintering larvae during 1999-2000. B. bassiana is one of the biological control agents of this pest. The fungus activity was not observed at two months of agricultural season in the year. May be due to the chemical pesticides which are applied from time of planting to heading stage in rice field. The different concentrations of 0, 0.2, 1,5,25, 125 and 625 mg/kg from active ingredient of Benomil, Edifenphos,Tricyclazole (fungicides), Diazinon, Carbaryl (insecticides), Butacholor and Oxadiazone (herbicides) on the fungus were studied. The effectiveness of chemical pesticides were examined in factoriol test in Randomized Completely Design. Statistical analysis showed that all of pesticides had effects on B. bassiana. Among of chemical pesticides only Benomil reduced mycelial growth and spores germination in concentrations above 25 and 125 mg/kg, respectively. But others pesticides postponded growth of fungus. The results revealed that the fungicides had the most inhibition than other pesticides, also effectiveness herbicide of Butacholor and insecticide of Diazinon were more than others two herbicide and insecticide. Consequently, chemical pesticides that are applied in rice field are one of factors that to prevent B. bassiana activities.

In order to investigate of various irrigation methods on the infection level of important diseases on cotton, this study was carried out in randomized block design in Hashem-Abad Research Station of Gorgan during 1996-1997. Three irrigation methods including: sprinkler (classic and mini traveling gun) and furrow were considered in randomized block design with 3 replications. Severity of infection to Verticillium wilt, Rhizoctonia solani and Alternaria leaf spot diseases measured in different treatments and analyzed statistically. Results indicated that the effect of irrigation systems on cotton Verticillium disease were significantly different (P<0.05). Percentage of infections Alternaria macrospore was much higher in sprinkler systems (classic and mini gun more than in furrow treatments) It was also found that severity infections of Verticillium dahliae was much higher in furrow treatment than in sprinkler systems. Sprinkling irrigation had no significant effect on the fungal diseases such as Verticillium, but they were increased the damage by Alternaria. Meanwhile, cotton infection to Rhizoctonia disease between three treatments were not increased during two years.

Determination of hydrologic parameters is important in view point of safety, project economy and efficiency of hydraulic structures. The runoff is one of the important parameters whose measurement has different limitations and therefore the application of hydrologic models in estimation of flood hydrograph is necessary. In this research an attempt has been made to compare the applicability of different statistical analysis methods to select the best one in developing rainfall-runoff model. To achieve the study goals, 15, 11 and 12 characteristics of hyetograph, hydrograph and their time spacing were considered, respectively, for 49 storms in Kasilian watershed. The study area located in the north of Iran and comprises 66.75 Km2. The relationships were investigated using bivariate in different forms viz. Linear, logarithmic, power, exponential, cubic, quadratic, compound, inverse, grow curve and S models as well as multivariate in different forms viz. stepwise, forward and backward after conducting Factor Analysis approach. The results of rainfall-runoff modeling process showed that the bivariate regression were mostly developed in the form of cubic, linear, compound and power models. Furthermore, consideration of results of multivariate regression verified the low accuracy of factor analysis method. Among other three methods, the stepwise and backward methods have had better performance, alternatively. The results of forward method were also similar to stepwise method.

Identification of areas susceptible to landslide occurrence is on of the basic measures in reduction of possible risk, and hazard management. The main aim of this paper was to compare applicability of two landslide hazard zonation models (named Haeri- Samiee model, and Mora-Varson model) in CIA-Rudbar watershed-For this purpose hazard map prepared for each of the models as a raster choropleth map at 1:50000 scale, and 1 x 1 grid cell size (estimated of relative hazard). Also current landslides were identified by type and morph metric dimensions, and finally mapped as landslide inventory map as ground thruth (hazard reference) through field works. Research results show that there is a significant correlation at the 0.01 level (p<0.01) between potential hazard values, and classes and the landslides number area, and the multiplication of the number, and area in each cell in the H.-S. Model. But there is not a significant correlation in the M.-V. Model. Therefore H.-S. Model is the suitable model for the study area and provided hazard map has high spatial compatibility to the current landslide inventory map.

Understanding ecological processes and associated complexities of river systems play an important part in defining their role and value as a unique ecosystem. Structural assessment of rivers helps to gain such an understanding, and ultimately is useful in interpreting relationships between abiotic and biotic components of the system. In the present study, scientific methods were used to assess the physical structure of the Madar-sou stream over the years 2000 - 2001. The length of Madar-Sou stream in Golestan National Park was measured as 19,913 m., 84/6 % of which were riffles and the remaining was recognized as pools. These characteristics increased the biological and physical diversity of the stream. The number, length and width of pools were varied from headwater (Sar-Cheshmeh) to downstream (Tangerah). A maximum number of 29 pools were sited along the 16th - 17th km from the headwater and a minimum of 2 pools were recorded in the headwater up to a length of km. The maximum and minimum width of pools were 3.75 and 1.86 m respectively. The maximum depth of pools was 120 cm. Gravel was the dominant bed structure. Overall, 370 pools were detected in the stream. The variation in the width of stream showed an irregular pattern and the medium width was about 5-6 m. The maximum height from sea level was 760 m in headwater and the minimum was 420 m in Tangerah. The direction of water flow in the stream was very varied but the dominant direction was from east to west. Madar-sou stream has a lot of variation in water level in different months and has many tributaries (convergent and divergent). The slope of stream ranged between % 1.5 - 2. The Information gathered in this study makes it possible to provide physical map of the stream at scales of 1:1000 to 1:50000. The maps and the information can be used in studies of interrelationship between the abiotic and biotic components of the stream and thus upgrade the ecological management of the system.

This paper addresses the association between biological index of nitrogen availability (Nava) and some physical, chemical and biochemical properties of soils. For this purpose, twenty soil samples were taken from different soil series of Isfahan province, central Iran. Particle size distribution, organic carbon (OC), Total nitrogen (TN), Cation exchange capacity (CEC), calcium carbonate equivalent (CCE), electrical conductivity of saturation extracts (ECe) and sodium adsorption ratio (SAR) were measured. Nava, L-asparagines and unease activities were also determined. Simple linear correlations revealed that Nava is positively correlated with QC and TN. ECe and SAR were negatively correlated with Nava. There were also positive associations between Nava and L-asparagines and urease activities. Multiple stepwise regressions revealed that 77 percent of Nava variation was only due to OC. It was concluded that the content of soil organic carbon plays a key role in bioavailability of nitrogen to soil organisms.

High level of salt in irrigation water and soil cause disorder in nutrient uptake, growth and yield reduction in wheat. Potassium alone and in combination with calcium sulphate is effective in decreasing the salinity hazard. This study was conducted to determine the effect of saline water, potassium and gypsum application on growth and yield of wheat (Triticum aestivum L. cv. Tejan). Four levels of potassium (0, 0.4, 0.8 and 1.2 g pot-1 K20), three levels of gypsum (0, 1.75 and 3.5 g pot-1) and five levels of salinity of irrigation water including 0.8 (well water), 3, 6 9 and 12 dS/m (mixture of Caspian Sea water and well water) were applied in a completely randomized factorial design in a greenhouse experiment during 2002-2003 growing season. The results showed that increasing salinity of irrigation water, plant height, spike length, flag leaf area, total dry matter, number of spikes per pot, number of grain per spike, grain weight per spike, and 1000 grain weight decreased significantly (p<0.01). Potassium application decreased the salinity hazards and improved grain yield and yield components. Interactive effects of potassium and saline water in total dry matter, 1000 grain weight and grain yield were significant at 1 % level. Furthermore, gypsum application had a positive effect on yield, total dry matter and 1000 grain weight. Interactive effects of salinity and gypsum in total dry matter and 1000 grain weight were significant at 5% level. Meanwhile, interactive effects of salinity, potassium and gypsum in 1000 grain weight and yield were significant at 1 % level.

A field experiment was carried out to study the effects of plant density, and nitrogen application methods on yield, and yield components of grain maize (Zea mays L.)(SC 704 hybrid) at Bakhtajerd Agric. Exp. Sta., Darab, Iran in 1998. The experiment was conducted as a split plot arranged in randomized complete block design with four replications. Treatments consisted of three plant densities (5.33, 6.67 and 8.82 plants m-2) as main plots and five N application methods (all N at planting, 1/2 at planting, and the rest as topdressing, 1/3 at planting, and the rest as topdressing, 1/4 at planting, and the rest as topdressing, and all N as top dressing) as subplots. The total applied N was 240 kg N ha-1. OF of Nitrogen topdressing was applied in stages 5-7 leaves, 12-14 leaves, and tassel appearance growth stages. Results showed that increased plant density did not significantly affect the ear number per plant, and harvest index. Increasing plant density from 5.33 to 6.67 plants m-2 had no significant effect on 1000-seed weight, but seed number per ear, grain, and proteins yield significantly decreased with increased plant density to 8.89 plants m-2. The highest grain and protein yield were obtained at 6.67 plants m-2. Nitrogen application methods had a significant effect on seed number per ear, 1000-seed weight, seed and protein yields. The highest rates were obtained when N was applied as 1/4 at planting, and 3/4 as topdressing which was not significantly different with applying 1/3 N at planting, and 2/3 as topdressing. It was generally concluded that the highest seed, and protein yields was obtained with planting 6.67 plants m-2, and applying 1/4 N at planting, and the rest as topdressing.

Based on the results of in vitro and field experiments, eight genotypes of durum wheat [Triticum turgidum L. subsp. durum (Desf.) Husn.], comprising three salt tolerant genotypes and one salt sensitive genotype from each of which, were selected and used in this study. Genotypic responses to salt stress at seedling stage were assessed under greenhouse conditions with salinized solution culture at control 0 mM, 75 mM and 150 mM NaCl concentrations using supplemental Ca2+. Plant dry weight, relative growth rate, relative water content and Na+, K+ and accumulated in the hydroponically grown seedlings were measured at 10 and 20 days after salinity treatments. Results indicated that plant dry weight is affected significantly (P<0.01) by both genotypes and salinity levels in a way that salinity increments caused plant dry weight reduction. Relative growth rate and relative water content of genotypes were influenced with different rate under salinity levels. Increasing salinity levels during both 10 and 20 days periods caused increment of sodium concentration and reduction of potassium concentration and K+/Na+ ratio. There was a significant difference for mean of plant dry weight between in vitro tolerant genotypes (97.2 mg/plant) and field tolerant genotypes (85.6 mg/plant) under 150 mM NaCl treatment after 20 days salinity. In vitro salt tolerant genotypes (ITGs) "Dipper-6" and "Prion-l" produced the highest dry weight, growth rate and K+/Na+ ratio under salt stress conditions (150 mM NaCl) in the greenhouse. It is concluded that durum wheat genotypes, selected from in vitro saline conditions, performed successfully at the seedling stage.

In order to determine tillering, yield and yield component of Promised bread and durum wheat three experiments were conducted in Safi-abad Agricultural Research Center, with three 15/9, 15/10 and 15/11/1998 planting date. The trials were randomized complete block design with four replication as six wheat varieties, Falat, Atrak, Zagroos, Durum 13, Durum 12 and Chin altar in main plot and five seed densities 50, 100, 200, 400 and 800 seed per m2 in sub plot. Tillers number per plants and wasting, spike number per m2 , seed number with spike and thousands seed weight were reduced with delay in plant date of increase in seed densities. Also with raise in densities tillers per plant were decreased, tiller mortality and spike number per m2 were increased. Competition between plants in 800 seeds per m2 were caused such decline in spike less than seeds number per m2. In every planting date seed number per spike and seed thousands weight were decreased so seed number per m2 were raised. There was not any significant differences between seed yield in planting date, but this factor were exceed significantly with add to seed number per m2. As delay in planting date, seed number per m2 must be increased.

Larval behaviour and melanin plug status in spiral intestine in the timing of first feeding (9, 10, 11, 12 and 13 days post hatch) with a live food (artemia naupli) on Persian Sturgeon at 17.7± 0.8 and 18.1± 0.4°C was examined. The Study of larval behaviour exhibits that most of larvae become negative photo taxis and exhibit benthic behavior from 5 and 6 days post hatching at 18.1± 0.4 and 17.7 ± 0.8°C, respectively; and from 10 and 13 day post hatching, most and all larvae come out of benthic state, and swim on surface and column water. Daily observations of digestion system exhibited when sufficient and suitable food is provided to larvae from the timing of initial feeding, although larvae have melanin plug in spiral intestine, they can capture and eat live food. Thus, expulsion of melanin plug cannot really be used to determine the time of active feeding.