Journal of Agricultural Sciences and Natural Resources
Year:2005 | Volume:12 | Issue:4|Papers Count:24

Design of alluvial canals by using regime equations has been a subject of research during recent decades. The underlying theory dictates that for a canal in regime, water discharge, sediment load, canal geometry and slope, as well as other flow variables should be in equilibrium. For the design of alluvial canals, a number of regime equations have been developed by investigators such as Lacey, Blench, Simons and Albertson, Parsa and Javan. In the present study, applicability of the above regime equations was investigated. Then based on field data modified equations were presented. Field data included the measurement of flow discharge, flow velocity, geometry of canal cross section and slope of water surface in 29 earthen canals. The sizes of bed and side materials of these canals were also measured. Comparison of different regime equations indicated that the equation by Parsa and Javan provided a better estimation of hydraulic parameters as compared with other equations, because in this equation, flow width and depth were related to slope as well as flow discharge. Since in Parsa and Javan equation water surface slope was an independent variable, their equation can be applied to a wide range of flow conditions. Since all other equations were developed using local data, they can provide good results, if used in similar conditions. Therefore, in Komfiroz area their use did not lead to suitable results. For the case of Simons and Albertson equations, they were comparable to Parsa and Javan results. This was due to fact that their equations did not include limitations as imposed by other investigators. Using slope as an independent variable can predict the equilibrium conditions with more accuracy.  

In order to investigate the effects of deficit irrigation management on rice yield at transplanted (TP) farming a field experiment was conducted at Rice Research Institute (Mazandaran, Amol) during 2000-01 on rice, Tarom variety. The treatments included seven levels of irrigation managements. The experiment was arranged in a randomized complete block design (RCBD) with three replications. Objectives of this study were improving water productivity (WPI and WPI+p) and get reasonable yield. Results indicated that there was a more significant difference in yield between treatments (α≤0.01). Maximum paddy yield was for T1 (whole submerged soil: 5 cm water) with 4373kg ha-1and minimum paddy yield was for T7 (saturated soil during whole growth season) with 3943kg ha-1. Amounts of WPI+p and WPI for T7 were 6.1 and 7kg mm-1respectively. At T7 treatment with 42 percent reduction of water use, only 10 percent decreased paddy grain yield. Results showed that it is not necessary to maintain the rice field submerged in whole growth period. Using this method it is possible to increase productivity of irrigated field and deficit irrigation method can be applied without noticeable yield reduction.  

Soil infiltration capacity is one of the main important factors to design soil and water projects such as irrigation and drainage systems. Both maximum sprinkling application rate and irrigation scheduling are frequently based on soil infiltration and final infiltration capacity. Although soil infiltration capacities of different parts of a field are not the same, the final soil infiltration capacity should be estimated carefully using an adapted method to sprinkler irrigation to avoid runoff and erosion in order to achieve high irrigation efficiency. In this paper a physical-mathematical model was used to predict soil infiltration capacity under sprinkler irrigation conditions. The results showed good agreements (r2=96-98%) between measured and predicted infiltration capacities on both basin and furrow experimental plots. Final soil infiltration capacity and capillary drive could also be predicted using the model for two different times of ponding at different application rates.  

Tissue culture systems provide a high efficiency for mass propagation of desired disease-free plants as well as genetic improvement. Considering these facts and the importance of olive crop, some experiments were carried out to investigate the in vitro establishment of three olive cultivars. For this purpose, single nodes were taken from mature container grown 'Manzanilla', 'Dezfoul' and 'Zard' olive cultivars. To find out the best disinfection method, different concentrations of NaOC1 and HgCl2 were used. Three sampling times i.e. 4th of February, 5th of May and 6th of August and three culture media i.e. OM, MS and MS with half strength of macro elements (1/2MS) were compared to optimize shoot establishment. The most important contamination agent was diagnosed and the controlling effect of Cefotaxime antibiotic was evaluated. Furthermore, the effects of two cytokines: Benzyladenine (BA) and Zeatin on establishment were evaluated. The Results showed that treated explants with 0.1% HgCl2 for 3 min. followed by three times rinsing with sterile distilled water was the most appropriate disinfection method. Explants, which were taken on 6thof August and grown in 1/2 MS medium, gave the best results. The main contaminating agent was Pseudomonas bacterium which was controlled by Cefotaxime at 100 mg/I. adding 0.5 mg/l BA to 1/2 MS medium improved in vitro establishment of olive explants.  

In order to develop some quantitative characteristics in tuberose, an experiment was performed by using factorial design randomized complete blocks in Mashad Astan ghods garden. In this experiment, unit corms soaked for 24 hours by gibberellic acid (GA3) and 6-banzil adenine (6-BA) each one in four levels: 0,50 and 150 ppm and then they planted in 3 replicates in outdoor in April 1382. The results of variance analysis showed that the numbers of florets per spike affected by Kind of hormones, but concentration and interaction effects of hormones and concentration had no effects. Length of spike rachis affected by concentration and interaction effects, but the kind of hormone had no effect on this characteristic. These results also showed that length of spike rachis decreased by increase concentration GA3. GA3 with 150 ppm concentration could decrease the days need for see the first spike, changed the means for this characteristic to 76 days. 6-BA with 50 and 100 ppm concentration for days need to see the opening florets from initiation of first spike, was better than the other treatments. The height of plant at initiation stage of spike and numbers of off-sets characteristics had no affected by concentration hormones and interaction effects. GA3 with 50 and 100 ppm concentration could change the height of spike to 94.32 and 94.67 cm, respectively. The diameter of spike affected by hormones, concentration and interaction effects and 6-BA with 150 ppm concentration increased the diameter of spike to 7:33 mm. These hormones had no effects on number leaves at initiation of first spikes characteristic either. GA3 increased length of spike and plant height, but 6-BA increased the number of florets in each spike.  

Organic fertilizers have an effective role in soil physical properties, increasing soil fertility and reduction of erosion. In this research, cumulative and residual effects of organic and chemical fertilizers were studied on soil infiltration rate by applying manure, sewage sludge and chemical fertilizer treatments, each with three replications. In manure and sewage sludge treatments, 25, 50 and 100 ton/ha, and in chemical fertilizer treatments 250 kg/ha were applied to plots for three consecutive years. To study the residual effects of these organic matters, they were applied to some plots for only one year and to another set of plots for two years. Nothing was added to control plots. Corn and wheat were grown in the plots. Infiltration rate was measured in the third year by double-rings method. Infiltration equations of Kostiakov, Kostiakov-Lewis, Horton and Singh and Yu and four combinations of these equations were fitted to the measured infiltration values. The results showed that in most cases, Singh & Yu equation fitted better than the other equations or combinations and its mean error for estimating instantaneous infiltration rate was the least. The worst fit was for Horton equation. Final infiltration rate (fc) in control treatment was 10.32 mm/hr. In chemical fertilizer treatment, addition of fertilizer for three years was effective in increasing fc, but the difference was insignificant with other years. Fc value in manure treatments was more than control, and the differences were statistically significant. Fc value of 100 ton/ha manure treatment in the third year (227.88 mm/hr) was the highest among all the treatments. In sewage sludge treatments, fc values were significantly different from control, and twice application resulted in higher fc value (103.21 mm/hr) with respect to once and three times application. Cumulative depth of infiltrated water was significantly different between all organic and chemical fertilizer treatments and the control.  

In order to study the effect of moisture stress and nitrogen deficit on yield and yield components of maize, an experiment was conducted in two locations, College of Agriculture of Tarbiat Modarres University and Kermanshah Razy University. In this experiment, four levels of moisture stress, moisture stress at vegetative stage, reproductive stage, both vegetative and reproductive stages and without moisture stress or control treatments, were randomized to main plot units and combination of two levels of nitrogen fertilizer (200 kg/ha and 100 kg/ha, nitrogen) and two maize varieties (S.C.647 and T.C.647) were randomized to subplot units. In this study, the maximum yield and yield components were obtained from control treatment and was not significantly difference with moisture stress treatment at vegetative stage. Biomass, yield and yield components were reduced in treatments with moisture stress at reproductive and both vegetative and reproductive stages, but there was not significantly difference between these two former treatments for yield and yield components. Nitrogen deficit had negative effect on yield and yield components in control and stress treatments, but significant difference was not observed in other traits. T.C. 647 variety had better relative drought tolerance than S. C. 647 variety. Yield and yield components of varieties were often better in Kerman shah than Tehran.  

In order to determine the best row spacing and plant to plant in row on the grain yield of medium maturity hybrid corn (KSC 647) in Mahidasht Research Station in Kermanshah province, a field experiment was carried out for two years (1999-2000) in Randomized Complete Block Design with 8 treatments. In this investigation two row spaces (60 and 75 centimeters) and four plant to plant distances were used. Plant densities ranged from 70,000 to 104,000 plants per hectares. Combined variance analysis showed that the grain yield for 60 cm in row spacing with 8733 kg/ha was higher (9%) than 70 cm in row spacing with 8007 kg/ha respectively. The highest grain yield was obtained from 75cm row spacing with 17cm plant to plant in row and 60cm row spacing with 23.5cm plant to plant in row with 9090 and 9120kg/ha respectively. Simple correlation coefficient of plant height, kernel deep, weight of thousand seed, number of seed row per ear, number of seed in row and yield in relation to number of plant in unite surface area was equal to -0.393, -0.680, -0.558, -0.500, - 0.673 and -0.373 respectively. The majority parameters to yield and yield component showed negative correlation with increasing of plant number in unite surface area. So, grain yield in unite surface area is reduced and it may be related to yield component decreasing in cornfield with 77000 plant per hectare in temperate region. Backward regression analysis was also done for plant density (dependent variable) and other characters as independent. Finally, the correlation between five remaining characters in the model was divided into direct and indirect effects by path analysis. The results derived from correlation and path analysis indicated that cob percent and kernel deep direct effects 1.083 and -0.967 were greatest factors affecting plant density respectively.  

Different responses of crop varieties to various environmental condition characterized as Genotype environment interaction. Evaluation of G*E interaction is very important for releasing of new and stable variety of the plant in different regions. In this study, the adaptability of seven hybrid genotypes of cotton, along with two controls (Sahel and varamin) were evaluated in five regions of Golestan province for two years. The seeds of genotypes were planted in a completely randomized block design with four replications. Simple and combined analysis of variance indicated significant difference among genotypes for evaluated traits. This analysis also showed that there are consider interaction between genotypes by location over years. Results indicated that hybrid coker 312×C1211 for yield, hybrid coker 312×153F for maturity and hybrid Hopicala×349 were better than control (Sahel). To study mode of stability for the genotypes we use indexes such as Regression coefficient, Deviation from regression, coefficient of determination. The results showed the hybrid coker 312×C1211 had a great and suitable stability for most regions of Golestan Province. Also the findings revealed that study of stability for cotton genotypes is very important in Golestan regions, because evaluated locations in this study were highly valuable in response to environmental conditions over the years.  

In order to investigate the effects of sowing date and Rhizobium inoculation (RI) on yield and its components two cultivars of soybean, a field experiment was conducted in 2002 at Agricultural Research Station of Gharakhil (Ghaemshahr) using a split-plot factorial arrangement in randomized complete block design. Experimental treatments were sowing date (8 and 18 May and 28 May and 7 June), cultivar (Williams and Line 20) and inoculation (RI and no RI). Statistical analysis showed that sowing dates were different with respect to pod number per plant, seed number per plant, seed weight and grain yield, but not for seed number per pod. Cultivars were significantly different with respect to all the measured traits. RI significantly increased all measured traits, except for seed number per pod. RI was more effective in sowing dates of 18th and 28th of Ordibehesht, probably due to more opportunity for bacterial activation and nitrogen fixation.  

Citrus branch wilt, decline and death disease caused by Nattrassia mangiferae is one of the most devastating diseases of citrus in Khuzestan province and causes heavy losses in this region every year. The aim of this investigation was to examine the chemical control measures against this disease. The relative resistance of some citrus varieties to pathogen was tested with infection of two-year old scions in two separate experiments. In first experiment Lisbon lemon was the most susceptible. Laboratory experiments were conducted to evaluate the effect of six fungicides including Propiconazol, Copper oxychloride, Zineb, Benomil Tricyclazol and Mancozeb against the pathogen on PDA culture. Results indicated that, Propiconazol was the most effective in inhibiting growth fungus. The EC50 of fungicides on PDA culture to N mangiferae were determined. In an attempt to find a biological control method, antagonistic effects of Trichoderma longibrachiatum, T. harzianum, T. harzianum 199, T. virens were studied on N mangiferae. In dual culture experiments and cultures on complete colony of N mangiferae, antagonists colonized the pathogen. However no antagonistic mechanisma ie: coiling, vaculization and lysis occurred. Volatile metabolites of Trichoderma spp. Did not inhibit growth of pathogen.  

In order to determine the fungi associated with decaying rot, crown and leaf of lawn in different parts of the Gorgan city, 34 samples were collected at four season of 2001-2. For this purpose, pieces of decaying and discolored parts of the root, foot and leaf were surface sterilized with commercial sodium hypochlorite (0.5%) for 1-2 minutes, and cultured on an acid and non acidic PDA and MA media. Isolates were obtained and divided into 4 groups, on the basis of morphological characteristic identified. Then pathogenicity tests were carried out by spraying 10 ml/sp spore of each pathogen inoculation on seeding lawn in greenhouse. The results showed that, 4 species were associated with the disease, and among them F. culmorum was the most frequent (25 cases), which is considered to be the main incitant of crown lawns. Bipolaris spicifera and Alternaria alternata were the most frequent (17 and 22 cases respectively), which are the cause of Brown spot of leaves and some necrotic of foot. Also, Rhizoctonia solani with the Lowest frequency 13 cases of isolation caused foot canker and drying rot. The results indicated that the pathogenic associated with moisture stress.  

In this study one hundred twenty pseudomonas fluorescens isolates were collected by use of King's B medium from field soils of different regions Khuzestan province including: Dezfu1,Shoshtar, Shosh, Mollasani and Sosangerd. Only three isolates had suitable antagonistic and biological effects on Rhizoctonia solani, the casual agent of been seedling damping off in laboratory experiments. These strains were identified by current methods in bacteriology and belonged to Pseudomons fluorescens. Each strain showed significant effect on dead plant percent reduction in compare with check. But effect of strain 24 was more than the others. These bacterial strains produced a kind of metabolite on PDA (containing 5% glucose) that could inhibit the growth of casual agent of seed rots and seeding damping off in the absence of bacteria. This metabolite seems to be art antibiotic. Anyone of strain did not produce siderophor on PDA (containing 5% glucose) amended with different concentration of FeCl3.  

During 2002-2003, a survey was conducted in citrus orchards in west of Mazandaran. A disorder was observed on fruits, leaves and twigs of pame mandarin Citrus reticulata (Minneola tangelox Clementina). Young fruits and leaves mostly drop. The remained fruits on trees have low quality. In order to identify the causal agent of the disease, symptomatic leaves, twigs and fruits were collected from orchards and surface disinfected with hypochlorite sodium. Samples were cultured on PDA and incubated in 27°C for 7 days. Purification was done by single spore on water agar. Fungal colony had an olive green to dark brown colour and 15-25 mm growth mean per day. Conidia had different size, 1-7wall length and 1-5 septums. Pathogenicity tests were carried out by using the spore suspension and fungus disk on detached leaf and fruit in a container with humid condition in room temperature. Most of isolates induced brown spots on leaf and fruit of page mandarin, while there is not any symptom in the treatments with distilled water in the same condition. The pathogen of brown spot reisolated from infected tissues. According to morphological characteristics and references the cause of disease was identified as Alternaria alternata PV. Citri. This is the first report of the occurrence of brown spot of page mandarin in Iran.  

Arthropods have an effective role in equlibrating of ecosystem food chains, but most chemical compounds disconnect these chains. Biological effects of three commonly used insecticides (Diazinon, Etrimfos, and Chlorpyrifos) on population density and activity of many non - target arthropods was in a soyabean (Glycine max) crop in randomized block design with 4 treatments at 4 replications. The arthropods were Coccinella septempunctata L. (Coccinellidae), Chrysoperla carnea Stephens (Chrysopidae), Carabus sp. (Carabidae), Scarabaeus sacer L. (Scarabaeidae), Forficula auricularia L. (Forficulidae), Aphidoletes aphidimyza (Aphidiidae), different species of- ants (Formicidae) and spiders (Araneae). The insecticides had significant effect on population density of ladybird, lace wing, carabid beetle, earwig, parasitoid wasp, and ants, but had no significant effect on S. sacer and spiders because of their feeding on animal waste and live prey, respectively; therefore, their population density was rather constant. Of the influenced arthropods, parasitoid wasp was more susceptible than the others, and its scratched population was recovered very slowly and in a long term. Also population recovery of ladybird was faster than other arthropods. In despite of mortality, the insecticides caused stimulation and increased activity in carabid beetle, earwig, and ants. Of the three insecticides, Etrimfos had lower effect on reduction of non - target arthropods' population density than Diazinon and Chlorpyrifos, and population recovery in the Etrimfos plots was faster than other treatments. Therefore, on the bases of the results of present research, Etrimfos is rather compatible to biocontrol agents in Integrated Pest Management (IPM).  

Flood events cause extensive human and financial losses in the world every year. The process of land use change, urdanization, inappropriate construction and occupation of river side lands have great effects on this hazard. This study was carried out in Ziyarat river flood plant which, large area of Gorgan city is located in its floodplain. For this reason, first topographic and land use maps of the urban watershed of Gorgan has been digitized for using in GIS. According to topographical conditions, the study area was divided into 15 sub-watersheds. Also, according to hydraulic and hydrological conditions of river, this river was divided into 9 reaches. Then flood hydrographs in 2, 5, 25, 50, 100 and 200 years return. periods estimated by Muskingum-Cunge method. Geometrical characteristics of reaches in 55 cross sections have been determined by field surveying. Water surface profile in each has been calculated, using HEC-RAS software for every return period. Then flood hazard maps of the study area have been prepared in ArcView GIS. With overlaying flood hazard land use maps, the flooded area and mean depth of floods have calculated. Finally, according to the results of this research, suitable management approaches have been proposed.  

Increasing seedling emergence capacity of service tree was the main goal of this research, which was carried out in Urime1knursery, located at 1550 meter altitude, northern aspect in Farim Forest Co's nursery in north of IRAN. In order to suggest the most suitable method of seed sowing for Sorbus torminalis, three treatments of planting date including: planting by 20th Oct and 20th Dec and 20thFeb and three treatments of soil mulching (with mosses, with gunny cloth and without covering the soil) were studied by using factorial experimental design in 4 replications. Analysis of variance showed a significant difference between three planting dates at 1% level of probability. The average of emerged seedlings in the 20thOct was more than the two other dates. Also there was a significant difference between the three levels of soil mulching factor only in planting of 20thOct. The average of emerged seedlings in the covered plots by gunny was greater than the plots that were covered by mosses. And the plots that were protected by mulch were better than unmulching plots.  

In a study that accomplished on 117 Maral (Cervus elapgus) populations in Golestan National Park, two age groups (fawn and adult) were distinguished for any of two sexes (age structure). In this experiment 71% of population was female (including 55% adult and 16% fawn) and 29% was male (including 15% adult and 14%juvenile).Populations of 6 different area in park have been studied in 5 replicates. These habitats had different population in herd size with 95% liability. There were 5 age groups of Maral population and the percent of middle-aged and upper aged male Maral population were less than usual limit (means 3%). The ratio of calves as compared with does was 7%. In order to study of roe deer population, 4 transect with 5 replicates and totally with 8-Km area have been established. The sex ratios of roe deer (Capreolus capreolus) were 38% males, 15% immature and 47% females. Moreover, density and abundance of roe deer in shrub land 95% liability were more than open forest. The sex ratio of roe deer was 2.5 female for 1 male.  

The utilization of beech waste veneers collected from a veneer mill for manufacturing oriented strand board (OSB) was studied. Core strand orientation (parallel to the surface layer, right angle to the surface layer and randomly oriented), press temperature (170°C and 190°C) and press time (10 min. and 15 min.) were considered as variables. Strand dimension, board thickness, board density, resin type, resin amount, press pressure and press closing time were kept constant for all manufactured board. Physical and mechanical properties of boards were determined. Results showed that when strands laid parallel to the surface layer, Modulus of rupture (MOR) and Modulus of elasticity (MOB) reach the highest values however the highest internal bond and lowest thickness swelling were observed in boards in which core strands were laid cross to the surface layer. Press temperature and press time had modifying effects on board properties. It was concluded that beech waste veneers' can be recycled and used as raw material for producing OSB.  

An experiment was conducted to investigate the effects of gossypol in cottonseed meal (CSM) on scrotal circumference (Se) and spermatozoa quality. Eight Atabay rams of 2 years old with an average body weight of 58±6.09were used. The isocaleric and isonitrogenous diets were calculated for the control and experimental groups contained %10 soybean meal and %15 CSM (containing 850 ppm free gossypol) respectively. Semen was collected for 12 weeks, and percentages of motility, live and normal spermatozoa were measured. SC was measured during the experiment every week. The results showed that the differences of SC and spermatozoa quality between the control and experimental groups were significant (P<0.01). The percentages of motility live and normal spermatozoa and SC in control group were greater than in experimental group respectively (69.57%, 77.25%, 80.61% and 33.55cm vs 62.48%, 74.59%, 59.36% and 32.72cm). The results showed that feeding 15% CSM reduced SC and rate of motility, survival and normal spermatozoa in Atabay rams.