Journal of Agricultural Sciences and Natural Resources
Year:2008 | Volume:15 | Issue:5|Papers Count:24

The purpose of this study was to investigate barriers in WCEs project. Using randomized sampling method 104 WCEs were selected. Data was collected through a questionnaire. (Faced and content) Validity of the questionnaire was examined by a panel of Agricultural Extension Experts and Tehran university professors. Using Cronbach's-alpha formula the reliability of questionnaire assessed (a=0.93). Data analysis was performed using Factor analysis. The results showed that nine factors extracted and named as lack of professional understanding with explaining 16.5% of total variance and other factors were respectively: insufficient Education and Monitoring, Logistic (Supportive), organizational, Land-related problems, cultural- Economical, Personal, Consul tent's Expectation, and natural risks factors. As a whole, those factors explained 77.5% of the variance.

In order to determining the mean stock growth of stands at the edge of asphalted and earthy forest roads and to comparing them with mean volume per hectare of adjacent stand which had located at the distance of 100 m from road edge, the inventory was performed in three northern forest site of Neka, Amreh and Darab Kola. In each of site, a road with the length of one kilometer was selected. Then, number per hectare and diameter at breast height of trees in twenty plots with a size of 1000 m2 which half of them had been established along forest roads and other had been established in adjacent stand, were measured. Volume table (Tarrif) was used to calculate the stock growth of stands at the edge of road and adjacent. The results of this study indicated that the stock growth of forest roads edge of the Naka and Amre was more than adjacent stands at probability levels of 0.1 and 1%, respectively. But in Darab Kola site, there was no significant difference between the stock growth of road edge and adjacent stand. The stock growth of forest stands at the edge of Neka asphalted road was more than the stock growth of stands at the edge of Amre and Darab Kola earthy roads at probability level of 5%. Maybe Alnus subcordata C.A.M abundance, light availability, soil fertility and creating a heat island around the corridor cause a stands stock growth rising at the edge of road in proportion to adjacent and also cause a stands stock growth rising at the edge of asphalted road in proportion to earthy roads which has need a accuracy investigation.

The main objectives of the present study were to investigate the effects of climate and slope position on the clay mineralogy of soils with loess parent material in Golestan Province. Clay minerals with their unique properties are the sites for ion exchange for plants and also considered as the source of soil nutrients. The abundance of each clay mineral having specific property influences the overall properties of the soils. Two transects of 200 and 300m length in Huttan (Maraveh Tappe area) and Gorgan regions were studied. Hutan and Gorgan regions have aridic-thermic and xeric-thermic soil moisture and temperature regimes, respectively. By considering the different landforms, four pedons in Hutan region and five in Gorgan region were studied. Mineralogical analysis revealed that illite and chlorite were dominant in both regions. Kaolinite was in lower amounts in both regions and was mainly of inherited origin. In Gorgan region, however, higher amount of smectite detected was mainly attributed as the transformation product of mica. This could point to existence of a more favorable weathering conditions leading to the transformation of illite and also chlorite in Gorgan region. Different slope positions have affected the clay mineralogy mainly due to the erosion of the surface soil. This had resulted in the decrease in smectite content in the surface horizons of the shoulder position.

In order to study the effects of different NaCl concentrations on germination components of 12 canola cultivars in three constant temperatures (15, 20 and 25°C) two experiment sets were used with CRBD design in three replications. The first one was done at 20°C with 5 osmotic potentials (including 0, -0.5, -1, -1.5 and -2 Mpa) to evaluate response range of cultivars to salinity. The second one, was designed with two constant temperatures (15 and 25°C) and six osmotic potentials (0, -0.5, -0.75, -1, -1.25 and -1.5 Mpa equal to zero, 8.57, 12.56, 17.14, 21.43 and 25.72ds/m) to evaluate the effects of salinity and temperature levels on germination components. Results indicated that all studied components including germination percentage, germination rate, radicle and shoot length and radical and shoot growth rate were affected significantly in all cultivars by salinity, but mean values for studied cultivars were not significant. This revealed that tolerance to salinity in all studied varieties is almost same. Also, results confirmed that 8.57 ds/m (-0.5 Mpa) can be considered as salinity tolerance threshold for most of studied components such as germination rate, shoot length, shoot growth rate and radicle growth rate. Also results showed that salinity tolerance threshold can vary from 8.57 to 17.14 ds/m (-0.5 to -1 Mpa), depend upon exposed temperatures. Also, increasing of temperature over than optimum temperature can result in synergistic effects with salinity levels to increase detrimental effects of salinity. Our results showed that optimum temperature for canola germination can be in a range of 15 to 200C and distancing form optimum temperature can be a cause of different responses in respect to germination components in canola.

This experiment was conducted to determine the effects of salinity (0, 8, and 16dS.m-1), varieties, as well as their interactions on germination characteristics and seedling growth in barley. Bomi, Torkaman, Eize, Siah, Sahra, 1-yeknavakht, 14G, 11G, 5G and 15G, were cultivars. The plots were arranged as factorial, using a completely randomized design with three replications. The study was conducted in Gorgan University of Agricultural Sciences and Natural Researches, research laboratory of collage of agriculture, in 2007. All character of this study expects stem dry weight, uniformity affected by salinity. Increase in salinity significantly decreased germination percentages, germination rate, and root length, stem length, seedling dry weight, and increased total conversation efficiency of seed reserves. Salinity affected all the traits adversely and significantly. The interaction of genotype and salinity were significance in the germination rate, Root length, stem length, seedling dry weight and Total conversation efficiency of seed reserves. The results this research shows that the modified cultivars have more resistance against increasing level of salinity and says this fact that seed modifying is successful in this manner. Of course more experiments are necessary.

In this study, in order to disinfect initial leaves of the sugarcane (Saccharum officinarum) variety CP73-21, five treatments were studied in a completely randomized design (CRD) with six replications.Sequential applications of 25% sodium hypochlorite for 10 minutes and 0.1% mercuric chloride for 30 seconds had the best results on disinfection of initial leaves. Six callus induction treatments were evaluated through a factorial experiment based on CRD with four replications. Murashig and skoog (MS) based medium supplemented with 3 mgl-1 2,4-D along with 0.1 mgl-1 and 0.3 mgl-1 BAP respectively, had the best results for callus induction of initial leaves. Regeneration of calli was studied using five treatments in a completely randomized design with four replications. Hormone- free modified MS (including casein hydrolyzate) and also modified MS with 1 mgl-1 BAP and 0.2 mgl-1 NAA were more efficient on regeneration. Root formation was studied using five treatments in a completely randomized design with four replications. Half- strength MS medium supplemented with 0.01 mgl-1 IBA was found as the best for root induction treatment. The regenerants passed different stages of acclimatization successfully.

The use of prebiotics, nondigestible dietary ingredients that benefically affect the host by selectively stimulating the growth of and/or activating the metabolism of health-promoting bacteria in the intestinal tract, is a novel concept in aquaculture. An 8-week feeding experiment was conducted to investigate the effects of dietary prebiotic inulin on growth performance, nutrition factor, survival and body composition of cultured juvenile Beluga (Huso huso). Three replicate groups of fish (initially average weight 16.14±0.38g) were fed diets containing prebiotic inulin levels ranging from 1% to 3%. The basal diet was contained 3% cellulose. The results of linear regression showed there was a negative relationship between some performance indices including weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER), net protein utilization (NPU), energy retention (ER), feed efficiency (FE), protein retention (PR) and supplementation level of inulin. At the end of trial, in group treated with 1% inulin showed a enhaced survival without any significance between treatment (P>0.05), and intestinal lactic acid bacteria (LAB) increased in this group to compare other groups (P<0.05). No significance difference in body composition was observed (P>0.05). The experiment indicated that the prebiotic inulin didn’t influence the increase of the growth performance in beluga juvenile and it is not appropriate for supplementation in the diet of cultured juvenile beluga.

Astringency of persimmon fruit is due to soluble tannins. Polymerization of these tannins by induced acetaldehyde produced during deastringency treatments, results in removal of astringent taste in fruits. In this study Japanese persimmon fruits cv. Karaj, were harvested at three different stages and were used for astringency removal process by saturated CO2 atmosphere inside closed polyethylene bags at two time levels of 24 and 36 hours. After induction of acetaldehyde production, for completion of astringency removal process, fruits were exposed to two time periods of 24 and 48 hours in ordinary atmosphere. Both 24 and 36 hours of CO2 treatments significantly reduced soluble tannin concentration compared to control and the astringent taste disappeared. Astringency removal treatments by CO2 and relative ambient conditions inside bags reduced fruit firmness and titrable acidity and increased color index and pH compared to control. Also CO2 treatments resulted in decrease the SSC of fruits. Astringency removal treatments by CO2 had no effect on ethylene production, therefore changes in fruit characters were due to CO2 treatment itself or acetaldehyde and ethanol production by this treatment.

Citrus with annual production more than 3.9 million tones occupies first place among horticultural crop in Iran and sixth place in world annual citrus production. Abscission of a lot of fruit before harvest in some citrus cultivars like Italian orange is a main problem that caused to reduce yield and income and also loss of tree resources. Regarding to average yield of Italian orange in Baharestan garden of Sari in "on year", annually about 7.5 tons crop per hectare abscise and destroy pre harvest. To evaluation and possibility of abscission reduction in this cultivar, a randomized complete block design (RCBD) was performed with 7 treatments: 1) control 2) 2, 4-D 3) 2,4-D and urea 4) 2,4-D and zinc sulfate 5) 2,4-D and sucrose 6) 2,4-D and GA3 7) GA3 and urea and 4 replications in Sari of Mazandaran in 2005. In third week of November, treatments were applied, then abscised fruits were counted weakly and percent of abscised fruit in different treatments was calculated finally. Calyx of harvested fruits was removed and auxin amount of abscission zone was measured. Results showed that abscission in all treatments except 7 had significant reduction compared with control. Treatments 2 and 5 with 64 and 65 percent reduction compared with control had the highest effect, respectively. Average of abscission reduction in treatments except 7 was 60 percent compare with control. 60 percent reduction in abscission is about 4.5 tons increase in yield per hectare. Auxin amount of abscission zone in different treatments showed that treatments caused increase of auxin in calyx and in treatments 2, 3, 4 and 5 was significant compare with control. Increase of auxin in abscission zone is possible reason to abscission reduction. So, regarding procedure of this experiment, 2, 4-D can suggest as an effective and economical way to reduce citrus pre harvest drop.

In order to evaluate the effects of site (climatic factors) on polyembryogenesis and vegetative embryogenesis phenomenon and determination of its relationship with seed starch content in orange (citrus aurantinum), orange seeds were collected from four separate sites located in North of Iran including Tonkabon, Babol, Sari and Gorgan. Germination percentage and rate, polyembryogeny percentage and starch contents of collected seeds were measured. Results indicated that collection site had significant effects on all studied characteristics except germination rate. The highest measured values for all mentioned traits (except germination rate) were belonged to Tonkabon's seeds, as statistical differences between achieved means for germination rate and percentage of Tonkabon's seeds were significantly different than other collected seeds. Germination percentageof Sari, Gorgan and Babol seeds decreased 11, 14.8, 15%, respectively in comparison with Tonkabon's seeds, while these values for polyembryony percentage were 14.6, 22.6 and 26.9%, respectively. Correlation coefficients between climatic factors and studied traits indicated that higher precipitation in Tonkabon, specially during summer has been one of important affecting factors on studied traits in this site. Also, correlation coefficient between germination rate and polyembryony with seed starch percentage were 0.7 and 0.65, respectively. A high correlation coefficient also was achieved between germination rate and polyembryony percentage (R2=0.83*, while correlation coefficients between germination rate and seed starch percentage & germination rate were not significant. Results indicated that highest positive effect on germination percentage belonged to maximum temperature, while minimum temperature didn’t affect it. Precipitation quantity had negative effect on germination percentage. Also, mean temperature had negative effect on starch accumulation in seeds, while precipitation effect was positive and significant. Polyembryony also had a negative and significant correlation with maximum temperature, but a positive correlation with precipitation.

Due to probiotic properties of Bifidobacteria, they have been considered in dairy industry. Probiotic dairy products are produced and used in some countries, but their production has not been started in Iran yet. In this research 8 Iranian isolates of Bifidobacterium were studied for their ability to survive in yoghurt after 1, 2, 7, 14 and 21 days storage at 4°C. Five isolates demonstrated good survival and were used for further studies in bifidus yoghurt. The selected strains from the previous stage, along with a standard yoghurt starter culture, were used to produce plain yoghurt. Physicochemical (i.e. pH, acidity and syneresis) and sensory properties of the products were examined. No significant differences (P>0.05) were noticed for physicochemical and sensory characteristics of the samples produced with standard yoghurt culture and standard yoghurt culture plus bifidobacterium isolates. However, using of the five Iranian bifidobacteria isolates could be used in dairy products without any considerable changes in physicochemical and sensory characteristics of yoghurts.

This experiment was conducted to determine the effect of Roxarsone, Avilomycin and Formycine gold on performance, carcass characteristics and hematological values of Ross 308 male broiler chicks in a completely randomized design. For this purpose, a control basal diet formulated according to NRC (1994) recommendations for starter (0-21d) and grower (22-42d) periods. Growth promoter additives including Roxarsone (200mg), Avilomycin (100mg), mixture of Roxarsone and Avilomycin (200 and 100mg, respectively), and two levels of Formycine gold (500 and 2000g) was supplemented to each Kg of the basal diet for preparing other treatments. Therefore, there were six dietary treatments. Each dietary treatment was fed ad-libitum to five replicate groups of 18 birds. The results of experiment indicated that supplementing of all feed growth promoters except for 500mg/Kg diet Formycine gold, improved broiler performance. Broilers were fed diet containing mixture of Roxarsone and Avilomycine had higher weight gain than control diet. Carcass and tight percentage was significantly influenced by supplementing Avilomycin and Formycine gold (0.05%), respectively (P<0.05). All growth promoter additives, especially Formycine gold (0.05%) significantly decrease serum cholesterol concentration (P<0.05), but had no significant effect on other blood parameters. Supplementing of Avilomycin or mixture of Roxarsone and Avilomycin resulted to decrease of crop pH. Based on results of this experiment, supplementing of Roxarsone, Avilomycin and their mixtures to broilers' diet improve weight gain and decrease meat yield cost.

This study was conducted to investgate the effect in L-carnitine of diets with different levels of protein on the performance and hematology value of ross 360 broiler chickens were kept for 42 days.The experiment consisted of six dietary treatments and four replicates per treatment with15 broiler chickens per replicate in a completly randomized design. Dietary treatments consisted of:1)Basal diet; 2)Basal diet with 125mg/kg L-carnitine.3)Basal diet with 250 mg/kg L-carnitine.4)low protein diet without L-carnitine. 5)low protein diet with 125 mg/kg L-carnitine.6)low protein diet with 250mg/kg L-carnitine.The results showed that during the xperimental period, brids were fed with sufficient quantity of protein had higher weight gain as compared to those were fed low protein diet (P<0/05). Reduciny of dietary protein level, caused significant increase in food intake and food conversion ratio (P<0/05).Also L-carnitine caused significant increase in ratio of the weight of breast and the weight of cookable chiken and significant decrease in the obdominal fat (P<0/05). Dietary protein and L-carnitine supplementation didn’t have any significant effects on the blood factors.

The objective of present study was to investigate the effects of various levels of vitamins E and C in milk and tris extenders on Atabay ram semen characteristics in liquid condition. Semen was collected from 6 rams and mixed together at once. Semen samples received different treatments in milk and tris extenders. Spermatozoa characteristics including percentage of motile and viable cells were assessed. This experiment was carried out in 3×3×5 factorial arrangement with the use of completely randomized design. Treatments were included various levels of vitamin E (0, 30 and 60 mg/ml), vitamin C (0, 150 and 300 mg/ml) and different storage times (0, 4, 8, 12 and 24 hour). Results showed that the effect of vit. E on motility and viability percentage of spermatozoa in milk and tris extenders were significant (P<0.01). The effect of vit. C on motility percentage of spermatozoa in tris extender was significant (P<0.05). The effect of different storage times on viability and motility percentage of spermatozoa in milk and tris extenders were significant (P<0.01). Mean comparison on the basis of Duncan test showed that the highest motility (%69.42) and viability (%71.62) of spermatozoa were obtained in tris extender containing 30 mg/ml vit. E. Therefore, use of vitamins E and C in tris extender and use of vitamin E in milk extender is recommended for storage of Atabay ram semen in liquid condition.

The objective of present study was to investigate the effect of various levels of Vitamins E and C in milk and tris extenders on Atabay ram semen characteristics in frozen condition. Semen were collected from 6 Atabay rams using artificial vagina and suitable samples were mixed together and subjected to different treatments in milk and tris extenders. Spermatozoa characteristics including percentage of motile and viable cells were assessed by electronic microscope. This experiment was carried out in 3×3 factorial arrangement on the basis of completely randomized design. First factor was various levels of Vitamin E (0, 30 and 60 mg/ml) and second factor was various levels of Vitamin C (0, 150 and 300 mg/ml). Results indicated that in frozen condition, the effect of Vit. E on motility and viability percentage of spermatozoa in milk and tris extenders was significant (P<0.01). The effect of Vit. C on motility and viability percentage of spermatozoa in milk and tris extenders was not significant (P>0.05). Mean comparison on the basis of Duncan test showed that the highest motility of spermatozoa in tris (48.48±0.087) and milk extenders (46.45±0.085) were obtained in level 30 mg/ml Vit. E. In conclusion, use of Vitamin E (30 mg/ml) in milk and tris extenders is recommended for storage of Atabay ram semen in frozen condition.

A study was conducted to investigate the nutritive value of dried pistachio epicarp and possibility of using it in lambs feeding. To investigate nutritive value, chemical analysis, gas production experiment, dry matter and crude protein digestibility by nylon bag method and determination of digestibility by in vivo method and two-stage Tilley and Terry method were taken. Pistachio epicarp included: 1.7 McalME/KgDM and its crude protein, crude fat, calcium and phosphorus were 10.67, 4.50, 0.53 and 0.08 percentages respectively. The and effective degradability of crude protein and dry matter were 74.06 and 76.14 percentage respectively and digestible organic matter in dry matter was 46.02 percentage. To investigate the possibility of using PE in animal feeding and determination of optimum level in diet, seven groups of ten male lambs (age 6 months and average weight 35.9±1.21 Kg), were fed for 90 days, iso-caloric, iso-nitrogenous diets, containing either no added pistachio epicarp (control) and added levels 10, 15, 20, 25, 30 and 35 percentage pistachio epicarp in rations. Feed conversions for the treatments were 8.56, 8.23, 8.60, 8.54, 8.60, 9.18 and 9.23 respectively and no significant differences between groups 1 to 5 were observed. After 90 days feeding, the lambs were slaughtered and dry matter intake, daily gain, body condition score, feed conversion and carcass composition parameters were measured. The results showed that feeding lambs with pistachio epicarp up to 25 percentage of total dry matter intake did not affect lambs performance, feed conversion, body and meat composition and health of animals significantly.

In order to evaluate fleece characteristics, wool samples of 451 yearlings F1 and F2's of Arkharmerinos×Ghezel (ArGh) and Arkharmerinos × Moghani (ArMo) were collected during a period of six years (1999-2004) and were analysed with Microprojector. The following traits including fiber diameter (μ), fiber diameter variability (%), staple length (cm) and percentage of wool, medulla and kemp were measured. The average of those traits for F1's of ArGh were 27.10±3.36 m, 36.60±7.84 %, 11.81±4.06 cm, 91.31±9.32%, 7.27±6.90%, 1.40±3.03%; and 26.33 ±3.41m, 34.64±9.36%, 10.15±3.99 cm, 95.41±4.70 %, 3.39±5.85 %, 2.01±2.65 % for F2's respectively. The average of those traits for F1's of ArMo were 26.18±4.11 m, 36.19±8.63 %, 10.95±3.34 cm, 88.90±9.28 %, 8.81±7.76 %, 2.27±2.47 %; and 26.99±3.7 m, 36.52±14.5 %, 10.09±2.92 cm, 94.60±6.36 %, 3.24±4.52 %; and 2.85±4.99 % for F2's, respectively. Fleece quality of F2's compared to parental average and F1's were in higher quality to reach standards for use in carpet and textile industry but it needs further research.

Maymand ancient region with about 69600 hectares area is located in 38 kilometers to northeast of Shahre Babak in Kerman province. The view of area is mountainous region with plains and hills in southern section that its mountains are follow of central mountains of Iran and Shirkoh mountain of Yazd. The altitude ranges is from 1860 to 2850 m. above the mean sea level. The range of temperature is between -17/8 to 40/4 C°. This investigation was done for collection and determination of medicinal plants of Maymand area. To introduction of medicinal and essenced plants of Maymand, collected plants carried out to herbarium and identified with some floras. Then with use of questionnaires and some related books we find medical and botanical characters of collected plants. Our study showed that 105 species belonging to 90 genera of 42 families were present. After determination of species we interviewed local people to find out the traditional medicinal uses. Lamiaceae with 12 species and Rosaceae with 11 species are main medicinal family in this region. In this research customary usage of traditional medicinal species, habits, useful organs, main property and taxonomic characters of plants were determined.

Root water uptake is very important in hydrological models. The main subject of this study was characterization the role of different part of root system in crop water requirement during water stress conditions. 11 cylindrical lysimeters with 25 cm diameter and 100 cm height were filled with clayloam soil. In the first group, soil columns were separated to 4 layers with 3 cm sand layers. In the second and third groups, there were 4 and 3 lysimeters, respectively. The first and second group, lysimeters were irrigated with subsurface method. Water stress was applied with decreasing the number of under subsurface irrigation layers. In the third group gravitational irrigation was applied on lysimeter 9 and 20 and 40 percent deficit irrigation on lysimeters 10 and 11 respectively. Sand layers in the first group (which were preventing soil moisture exchange) were used to characterize the real role of each layer's root in water uptake when surface layers been under water stress. Although the Root Length Density (RLD) in deep layers was lower than RLD in upper layers, Crop could increase its root activity in wet layers to uptake water and compensated water stress in dried parts of soil. Root water uptake in third group also showed that with increasing water stress because of deficit irrigation, the percentage of root water uptake from top layers was increased.

For increase efficiency of flood warning system In the Small and medium mountainous basins, where the response time of watershed is short and occurs flash flood, a short term Quantitative Precipitation Forecast (QPF) is necessary. The QPF allows extending the lead time of flood forecast in flash flood warning system and it becomes reliable. Accurate prediction of precipitation is one of the most difficult subjects in meteorology. an Artificial Neural Network; ANN model for forecasting the short-term rainfall in 15 Rain gage station on the Golestan 1 Dam' watershed in Gorganroud basin in Golestan Province is presented in this article. Hourly precipitation and some other meteorological data is trained with feed forward Multi Layer Perceptron for 1 hr ahead forecasting and is tested for 2hr pointy precipitation for each stations. The model results compared with Persistent forecasting method. The results show that ANN accuracy is better than Persistent method. To use moisture and temperature data improve rainfall forecasting. The model would capable to update rainfall forecasting during the storm and can be applied in watershed with concentration time 3 hr and more. The results of QPF Models can be couple with the Real time Rainfall-Runoff models and improve the lead time of flood forecasting for 2hr acceptably.

In this research, an experimental investigation of the process involved in delta formation and its progression in reservoirs has been undertaken. The process depends on hydraulic, sediment, and physical parameters of the reservoirs and their associated river. In this research, a number of the influencing parameters, such as water and sediment discharges in the river, the reservoir flow depths, and the entrance diverging angle of reservoir, have been studied. For each run, the rate of bed changes and progression of bottom set and crest of a delta in specific stations have been observed and recorded.The results showed that the rate of crest progression can be predicted using an exponential function (with exponent of 0.624). Submerged angle of sediment with d50= 1mm has been obtained between the range of 30 -40 degrees. Using dimensional analysis and SPSS software for the independent variables (progression of bottom set and crest of delta) and the dependent variables (dimensionless time, water and sediment discharges, reservoir flow depth), a multiple linear regression model to experimental data is fitted. Due to weak prediction of the linear model in the first stage of progression, an exponential model has been carried out for this stage. Using a combination of these two models, a combined model is developed. Analysis of this model showed that the average and standard deviation of discrepancy ratio (l) for the bottom set of delta are 0.99 and 0.139, and those for the crest are 1.005 and 0.211 which show a good prediction when the new model is applied. Sensitivity analysis of the new model showed that the discrepancy ratio, (l), for the bottom set and the crest of delta are not sensitive to water discharge and flow depth in the reservoir. However, the parameter is sensitive to the bottom set and the crest of delta in high and low sediment rates, respectively.

The severity and spatial characteristics of drought are two important factors that are crucial to be considered while developing drought contingency plans. This paper aims to investigate important Tehran province drought events from this view point using severity-area-frequency (SAF) curves and 3 months Standardized Precipitation Index (SPI). For this purpose, monthly drought maps were prepared for the period of 1971 to 2005 and their spatial variations were assessed. The results showed that the 1971, 1982 and 1989 droughts have return periods of 3 to 5 years. While the 1990, 1999 and 2000 are representatives of 10 to 20 year return periods. Finally, the 1997 drought, which is the severest drought within the recorded period, was identified as 100 years return period. These droughts can be considered as relevant patterns to show spatial behavior of the province droughts. However to interpret these pattern, it is necessary to assess the monthly drought maps as well as SAF curves.

Runoff has an important role in decreasing soil moisture and consequently declining yield of crops. Thus, investigation on spatial variations of runoff and factors affecting runoff is very important in selecting proper method for controlling runoff. The study was conducted base on field measurements of runoff at plot scale in order to determination of spatial variations of runoff and factors affecting runoff in soils of semi-arid regions. Field experiment was carried out in part of dry-farming lands of Hashtroud in south of East Azarbijan, Iran from March 2005 to March 2007. Study area was 30 km×30 km and 36 grids with a dimension of 5 km were considered on it. In each grid, three standard plots with a spacing of 1.2 m were installed and runoff volume measured at the plots under natural rainfall events. Based on results, study soils are clay loam and mostly have about 12.67%. During a 2 study period, 96 rainfall events with a duration time bigger than 30 minute happened and only 41 rainfall events were caused runoff in the plots. Annual runoff in 36 study grids varied from 137.123 to 482.072 liter per plot with an average of 327.157 lit per plot. The results indicated that runoff is significantly (R2=0.63, p<0.001) affected by coarse sand, organic matter and lime in study soils. Runoff also spatially varied in the study area. Spatial variability of runoff was simulated as spherical model with an effective range of 2.42 km. spatial pattern of runoff was similar to that one of lime (with a spherical model and an effective range of 2.42 km) in the study area. Runoff spatially declined when lime increased in the different points on the study area.

This research was carried out to find the casual agents of damping-off of some of the Chinese elm seedlings located at agricultural faculty of Gorgan University and to isolate its agents. In this order, some of the dried or semi-dried seedlings were transferred to laboratory in spring 2005. Roots, crowns and stems of seedlings were washed and disinfested in 0.5% NaOCl. 5-10 millimeter-pieces plated on PDA and incubated under standard conditions. Based on microscopic and macroscopic characters isolates belong to Fusarium spp. fungus. After purification of isolates on 2% WA with single spore method, those were identified based on the important morphological characters such as colony form and color, microconidia and macroconidia and formation of chlamydospore by valid keys. These 5 isolates identified as F. solani and F. oxysporum. Phathogenicity tests were performed by inoculation 150 ± 25 milliliter of spore/chlamydospore suspension 3×106 (spore/ml) around of the root of the seedlings. This study is the first report of Fusarium solani and F. oxysporum as causal agents of damping-off of Chinese elm in Iran.