Journal of Agricultural Sciences and Natural Resources
Year:2007 | Volume:13 | Issue:5|Papers Count:18

A proper understanding of factors affecting water distribution uniformity in sprinkler irrigation is important for developing water conservation strategies. The purpose of this study was to determine suitable value of water pressure in semi-portable sprinkler irrigation system under different conditions of wind speed. The standard ISO 7749/2 and single sprinkle method have been taken into account to determine uniformity in south-east region of Khouzestan province. The investigations showed that higher cu values are attained with 45 m working pressure and uniformity decreased as wind speed and working pressure increased. Results also showed that Uniformity decreased from 80 percent when wind speed exceeded from 4.2 mps. Therefore sprinkler irrigation is not recommended under windy conditions (W >15 km/h).

Evaporation from the soil surface has a significant role in hydrological cycle in nature, especially in arid and semi-arid regions. In these regions the main part of water which enters the soil, reaches the atmosphere by evaporation from the soil surface. The accumulation of salts in soil surface also occurs in regions with a high water table because of evaporation from the soil surface. The main difficulty for estimating the evaporation in field conditions is lack of simple relations with minimum input data. The goal of this study is to introduce an applied relation for calculating evaporation from the bear soil with the initial and real boundary conditions using a numerical, one dimensional and non-steady analysis for regions with deep ground water surface. Since the ground water is deep, a physical model can not be applied. In real conditions, computer model LEACHM was applied as a device for numerical solution of Richards' equation with initial and boundary conditions different from the previous examinations. Since this model required much entrance data, it was determined in laboratory and field, and the model was implemented there. The influence of changing entrance data on evaporation from the soil was examined and an applied relation for calculating evaporation from the soil with different initial and boundary conditions was given. The results of given relation have a good correlation with the computer model and water balance model done by filed examination. At first evaporation depth is calculated by which the final amount of evaporation for the distinguished period is determined. Another result of this examination is to introduce a relation for calculating the accumulated evaporation in a specific day by evaporation of the first day and final evaporation of the distinguished period.

Reference evapotranspiration (ET0) is an important parameter for designing of irrigation systems. This parameter can be measured by a lysimeter, or estimated by empirical equations. Due to lack of lysimetric data, then different equations can be with FAO-Penman-Montheith (F-P-M) as a standard method. In the paper ETo was estimated by evaporation pan methodin Gorganstation. Then other methods were compared with ET0 of standard method. In the evaporation pan method, ETo was estimated trom multiplication of pan coefficient (Kpan) with pan evaporation data. Kpan is estimated from different methods including Cueneca, Allen-Pruitt, Snyder, Modified Snyder and Orang.Regression and statistical analysis showed that Orang & modified Snyder methods are suitable estimations for daily ETo. Cueneca & Snyder methods for 10 day duration period ET0, and modified Snyder & Cueneca methods for monthly ETo predictions in study area and areas that have similar climate conditions.

This experiment was carried out for finding a suitable way in order to increase rooting percentage of sweetlime (Citrus limetta L.) cuttings in greenhouse. For this purpose, cuttings about 12-15 cm in. length were taken from one year old shoots in early of spring, summer and autumn. After treated with IBA, NAA and IBA at concentration of 0, 500, 1000 and 2000 mg/l without or with 2% ascorbic acid, the cuts were cultured in a sandy medium. A complete randomized design with factorial arrangement was used with four replications and five cuttings per each replication. After 60 days, number of grown and rooted cuttings, root fresh and dry weight was measured. Results were shown that the best time for cutting was early spring and IBA 1000-2000mg/1 with 2% ascorbic acid was the best treatment for increasing rooting of sweetlime cuttings.

In general, Loess sediments are one of the most widespread forms of eolian sediments. These sediments are usually yellow but grizzly and approximately 70 to 90 percent of their formation is silt materials. Iran loesses often are located in northeast region and in this research, sedimentology properties of loesses in Ghapan (semiarid climate) and Naharkhoran valley (humid climate) regions have been studied. The stages of this research consist of field operations, brief identification of loess components in sand part, morphoscopy study of Quartz grains and granulometry operations. In our reading concerning granulometry, the different components of sand with using wet sieve method and silt and clay components with the help of pipette method were separated and their weight percent were measured. The conclusions of this research concerning sediments indicated that, median diameters is between 4 to 11 microns and mean diameter is between 3 to 8 microns. Their sorting, skewness and kurtosis are very poorly sorted, fine skewed and platy kurtic respectively. The statistical conclusions indicate that the sediments which are found in Ghapan and the ones, which are found in southern Gorgan, have significant difference in median and mean diameters and sorting. Consequently the Ghapan loesses are coarser and their sorting is better, but they are equal from sight of skewness and kurtosis. Our investigation concerning the components of loesses in Ghapan region indicates that gypsy-clayey aggregates and some of the primary minerals are abundant, whereas in the southern Gorgan regions, secondary calcareous-clayey aggregates are great. Morphoscopy research concerning quartz mineral indicates that these samples are located in angular to semi angular class and they have not been moved much distance from their source locations. From the point of surface texture, quartz grains are mainly aureole and partially blur. The form of their aureole indicates that they have been taken from ancient rivers bed and have been deposited in eolian sedimentary environment and their blurring shows wind abrasion, color blending by Sesquioxids and secondary calcareous effect.

The objective of this study was to obtain relationships between plant leaf area (cm2 plan-1) with main stem node number, leaf dry weight (g plant -1), vegetative dry weight (g plant -1) and plant height (cm). An experimental design was conducted in the field at Agricultural Science Research Farm of the Gorgan University. Experimental design was a factorial arrangement of treatments based on randomized complete block design with four replications. The treatments were combinations of three sowing dates and four plant densities. Sowing dates were 6 Dec. 2003, 20 Jan. 2004 and 21 Mar. 2004. Plant densities were 15, 30, 45 and 60 plants m-2, Sampling was carried out to first pod (50% of plants with 0.5 cm pod at one of the 4 upper nodes with unfolded leaf, R3). At each sampling leaf area, main stem node number, leaf dry weight, vegetative dry weight and plant heights were measured. The power equation in linear form {ln(y) = ln (a)+bxln (x)} was used to describe the relationship between leaf area and the mentioned characteristics. This equation was used for all combinations of sowing dates and planting densities. Significant relations were found between leaf area and main stem node number (R2=0.94), leaf dry weight (R2=0.94), vegetative dry weight (R2=0.93) and plant height (R2=0.83). It was concluded that the equations could be used for estimation of leaf area or can be used in crop simulation models of chickpea.

Vesicular Arbuscular mycorrhizae fungi created a symbiosis with the root of agricultural plants, with improvement in absorbing some of the food elements will be a cause increase in plant growth. In this research, one species potential of endomycorrhizae fungi separated from a farm's soil were evaluated upon ontogeny process of counter effects on fungi and higher plants. In this scheme, in the first step, the fungi's spore separation and purification have been taken place with wet sieving. In the second step, inoculation and reproduction of fungi will take place with Sorghum vulgare plant helping and pot culture method. In the third step specifications regarding the spore, growth and development of fungi vegetative organs in root tissue, have been studied upon a careful microscopic survey. At fourth steps, the effect of spore concentration, light and nutrition solution concentration, have been studied on both plants maize and sorghum. The results have shown that in reproduction Glomus species, making use of new polluted roots as an inoculating matter is much more effective than spore. Statistical results show that in all three tests the effect of spore concentration, light and concentration of nutrition solution on the rate of colonization, based on t-test exams and analysis of Variance, between treatments there are a statistical meaning differential (P<0.05). About the role of original spore concentration and light, on the rate of inoculation and colonization percentage, the results show that increasing of spore concentration and light will increase rate of symbiosis and also increase of concentration of nutritional solution will decrease percentage of colonization.

Bacterial leaf streak (BLS) is one of the most important bacterial seed born disease of wheat and barley in warm and humid climates that caused by Xanthomonas translucens PV. Translucens and X t. pv. Cerealis. Attempts to control of this disease with bactericides have been unsuccessful. In this research, the antibacterial activity of some plant extracts and essential oils distilled from medicinal plants were studied. The assay was carried out in petri dishes containing Yeast Extract Glucose Nutrient Agar, in which there was a well in the center of each petri dish. After 48h inoculation of bacterial suspension on the surface of medium, the diameter of growth inhibition zone around the wells containing 12 ml of plant extract and essential oil was measured, and analyzed. The results of the in vitro trials showed that all of essential oils had antibacterial activities on these pathovars. In this regard, the essential oils of Mentha aquatica, M spicate, Echinophorea sibthorpiana, Hyssopus officinalis and Ziziphora persica showed the highest and the essentioal oils of Achillea bieberesteinii, A. millefolium, A. vermiculatus, A. tenuifolium and Teucrium polium showed the lowest antibacterial activity. Also, the plant extacts of Allium sativum andpeganum harmala showed the highest and plant extracts of Rosmarinus officinaslis and Artemisia annua did not have any antibacterial activity.

This research was conducted to study interaction between root-knot nematode Meloidogyne javanica and causal agent of tomato wilt (Fusarium oxysporum f.sp. Lycopersici) for showing the effect of nematode infected root exudates of tomato on spore germination and growth rate of fungi in lab. and greenhouse condition. In this research, we have been demonstrated that spore germination and growth rate of fungi on PDA+nem. Gall extract) 1% v/v) in petri plate condition were significantly increased) class d) in comparison to other parts of root) class c) and roots of healthy plant) class c) after 3 days and during latter days (p< 0.05). Accumulation of plant nutrition in the nematode gall, which is favorite for fungi, increased fungal growth and nematode gall colonization by fungi. So root knot nematode infection in relationship to fungi increased inoculum level of fungi and plant root colonization.

Some quantitative and qualitative traits as well as Verticillium wilt (Verticillum dahlia Kleb). tolerance in 9 cotton (Gossypiumhirsutum L.) hybrids and cultivars were evaluated in a field experiment at Karkandeh (Kordkouy) and Hashem abad cotton research stations in 1996-1997. The experiment was arranged in a completely randomized block design with four replications. Different traits as yield, earliness, disease tolerance, yield components (average of boll weight and boll number) and lint properties (lint percentage, lint length, miconair, and pressley index) were investigated. To compare tolerance of cotton entries to Verticillium wilt, disease index (DI) was calculated by multiplication of disease severity (DS) by percent of infected plants. The results of combined variance analysis indicated that, there were significant differences (P<0.01) between cotton entries for all traits. Based on combined means comparison results showed that Siokra 324 with the best Guantitative and qualitative characters and tolerance to Verticillium wilt is a releasable variety for Golestan province.

Biological control of Fusarium Head Blight (FHB) of wheat caused by Fusarium graminearum with bacterial antagonists was investigated. Two hundreds and ten bacterial strains were isolated from healthy heads of wheat and pathogenic fungus also was isolated from infected heads collected from wheat crop field in Gorgan and plain during spring 2003 after the dual culture method, six single bacteria and two mixture bacterial strains were selected for further investigation in greenhouse and field condition. Based on the biochemical, physiological and morphological characteristic the strains were identified as follows, strains 35 and 50 Bacillus subtilis, B. cereus, strains 32, 174 and 175 were Pseudomonas flourescens, and strain 64 was Erwinia herbicola. In virto test, antagonistic effect of volatile and non-volatile antifungal compounds, sidrophore, cellolase, protease and autoclaved filtrate were investigated and their inhibition on fungal growth rate was measured. In this research the effect of antagonistic bacteria on disease severity, disease incidence and the weight of 1000 grains in greenhouse and field condition were studied. In all of experiments mixture strains had better results than single isolates application and the results of this study indicated that all of strains had significant difference in comparison with control application of mixture strains in greenhouse and field condition significantly, had better result than single strains. With attention to that this research has been reviewed in addition to laboratory, greenhouse and natural conditions, the results of field experiments was similar to the previous processes. Therefore using biological control especially in the case of mixture bacterial isolates sounds to be applied.

This study, thin layer drying of wheat (Tajan) was modeled. A convective type experimental dryer was used. Drying experiments were conducted at inlet temperatures of drying air of 35, 45, 50, 60 and 70°C, initial moisture content %25 d.b., and four replications for each treatment. Four different thin layer mathematical drying models were compared according to their coefficient of correlation to estimate drying curves. The x2, root mean square error (RMSE) and coefficient of determination r2 were used as the primary criterion to select the best equation to account for variation in the drying curves of the dried samples. The effects of drying air temperature on the model constants and coefficients were predicted by regression models. The effects of drying air temperature on the Page model constants and coefficients were evaluated by a multiple regression technique. Multiple regression method used for calculating for simulation of moisture content during drying for each temperature values that x2, RMSE and r2 were used. The multiple regressions on the coefficients of that model for the effects of the drying air temperature gave r2, x2 and RMSE that are 99.38%. 000018 and 004, respectively. These results showed good agreement with the experimental data obtained.

Extension methods are means to communicate with clients. Generally, it is recommended extension agents use a variety of methods. Extension agents' ability to use different methods increase their teaching ability and makes it possible to select the most appropriate ones based on clients' characteristics. Extension organizations have to try to increase their staff awareness about extension methods and provide favorite conditions to use them. This survey research was conducted to investigate how extension methods are used in Fars province by natural resources extension agents.The results indicated that extension agents were best familiar with "lecture" and use it most frequently.They had the least familiarity with festivals (fairs), television educational programs and demonstration techniques; even they used these methods rarely. The research recommendations are: 1) planning in-service training for extension agents to learn more about different extension methods, and 2) improve the use of different extension methods.

In order to spatial organization and sustainable management of land use, ecological potential of the southeastern Caspian coasts was assessed in detailed level by developing a numerical model and in the context of 1227 environmental units. With the priorization of possible land uses by qualitative comparative method and considering of environmental protected areas, the basic land use planning map of the region was prepared at 1:100000 scale as a leading document for development and environment management. In addition, due to intense diversity of physical and cultural conditions and sensitivity of the region and in order to the extension of decision matrix space and alternative selection of executive agencies, two different scenarios have been established based on multi-purpose land use management strategy. Research results show that the number of differentiated environment units are much less than the expected number, and indicates to the intense changes of terrestrial and aquatic ecosystems and land use changes in recent decades. The potential of region for all kind of seven customary land uses at high classes and significant difference between number and area of possible land uses at 5% (P<0.05 and R^ 2 = 0.964) indicate to severe environmental diversity and high resolution of numerical model. Sensible difference of combination and spatial variation of kind of possible land uses and classes between two scenarios in coastal belt, first of all, implies to complexity of coastal belt to the nature and style of implementation and management of fisheries, touristic and conservational projects.

Estimation of quality and quantity of natural phenomena is very time consuming and expensive. So interpolation methods are the suitable ways used to estimate in no sampling locations. There are a lot of common estimation methods and it sounds low differences between them. In the other hand, every planning has been done on the basis of these estimations and if estimation is weak it will cause imprecise decision making. This study conducted to compare some interpolation methods such as (Nearest point, Moving Average, Moving Surface, Trend Surface and Kriging) to estimate some properties of soil surface. After sampling and measuring variables of gravel, sand, silt and organic matter, these variables were interpolated with above interpolation methods for some part of Mehr watershed. These methods were tested for three categorizes of site sample including 25, 45 and 70. For every category 30 samples that have not entered in interpolation were used for determining of accuracy assessment of interpolation methods. Finally, for every varjable error mean and mean square error indices calculated by actual and estimated data were used for estimate of accuracy and precision of prediction. The results of this research showed that Nearest Point for low sample data and Mean Average (Inverse Distance) for high sample data have more precision. For variables with medium sample, Moving Surface method (Linear Decrease) in comparison of to other methods is nearly more precious that it needs more research in this case.

One of the most important ideas in forest management is maintaining and developing of biodiversity. In order to assess plant diversity, quantitative indices of biodiversity were used in Marivan, Chenareh, Iran. At first, the study area was classified to 6 ecological grouping by combination method of CA-TWINS PAN and then diversity indices were measured for each class. Eight richness and evenness indices were calculated for each group. Duncan's multiple range comparison tests and correlation analysis were used for investigation of significant difference between groups and importance determination of indices in separation of ecological grouping. The results showed that richness and evenness indices correlation with each other significantly. Significant difference was considered between groups in above indices. Pielu J' index, Q statistics and Shanon- Wiener index were distinguished in separation of groups.

The aim of this research was to study a Chestnut-leaved oak (Quercus castaneifolia C.A. Meyer) forest stand and presenting of suitable program for its future. 33 circular 0.1 hectare sampling plots were taken using randomized systematic method. The type of woody species, diameter of breast height, total height, crown diameter, bole quality, annual increment of oak trees and logging history were recorded in each plot. Then, volume per hectare and width of annual rings of oak trees were determined. Results indicated that this stand occur in trunk and beam growth stages and 50 years old. In addition, studied stand was mixed and including two storey. Dominated species in the over-storey was oak and mean number per hectar of this species was 174, while total number per hectare was 246. The mean annual rings, annual increment and stock of this species were obtained 3.3 millimeter, 5.1 meter cubic per hectare and 284.56 meter cubic per hectare. The future procedures should be focused on increasing of stand quantity and quality, omitting undesired individtuals by silvicultural cutting and helping to regeneration by planting of seeds in plowed and raked or oak seedling.

The survival of sturgeon brood stocks after taking the ripeness eggs has an important role on sturgeon stock management. There are different methods for artificial spawning of sturgeon brood stocks. One of the methods is oviduct incision (Padushka method). This study was carried out by this method during October to November of 2002 in Shahid Mmjani aquaculture Center of Gorgan. In this study some artificial propagation factors (relative fecundity, egg fertility rate, fluidal egg quantity, size of eggs) of two groups of sturgeon brood stocks with oviduct incision (F1:156.95±13cm and Wt:27.97±7Kg) and Control group (F1:158.78±10.7 and Wt: 29.54±6.28Kg) were compared and non significant differences were observed (almost 65%) (p>0.05). in order to health recovery 22 individuals surgeries brood stocks kept for 3 months in the pen culture that situated in Gorgan bay and 14 individuals brood stocks were alive at the end of this period. The rate of collected eggs from brood stocks in the first time was 85%-95%. In general, taking of eggs by micro cesarean method was better than conventional method. Also no significant differences were observed in qualifying reproduction parameters between two groups (p>0.05).