Journal of Agricultural Sciences and Natural Resources
Year:2002 | Volume:9 | Issue:2|Papers Count:19

The aim of this research was the recognition of plant association and its relation with soil in Khoshkab zone. This study has done based on Braun-Blanquette method. In this method, first Phyllitieto-Fagetum minimal area of releves was identified, then 180 releves were sampled in this zone by cover / abundance table of Braun-Blanquette. With analysis prepared tables (raw, differential and final), two associations: phyllieto-Fagetum, Mercurialieto-Fagetum and three sub-associations: Cephalantheretosum-Fagetum, Epimedietosum-Fagetum, Vicetoxietosum-Fagetum were recognized. Soil profiles were digged to appropriate with plant groups and dominant type of soil was identified acid brown. With using scientific references, chemical and physical experiments of soil, ecological groups were investigated and behavior of these groups was evaluated to temperature, moisture, pH, light and nitrogen. Results showed that association of Phyllitieto-Fagetum express destruction stages of forest and evolution of soil toward hydromorphic brown soil, but association of Mercurialito-Fagetum indicates suitable condition in soil of zone.

Geologically, northern slope of Alborz Mountain is divided into Khazar plain and northern border regions based on structural and stratigraphic characteristics. In order to study the pushing movement of natural slopes, side slopes in cross sections and geological and geotechnical reasons of landslides in northern slopes of Alborz Mountains, three road axes of Ghaemshahr-Firozkoh, Sari- Kiasar and Rigcheshmeh-Dodangeh have been selected. These regions are formed mostly of eluvial deposit like silty clay or clayed silt along with fine sand, which has a weak firmness. Flowage of water in the superficial layers, causes surface landslides along the slopes, so that thickness of slipped materials is about 6 to 7 m. By analyzing the results of the soil mechanics tests, the causes of failure of landslide are explained. In general, layering of the soil stratum with respect to land slope and dip of soil layers, which are the effective causes of the trenches and embankment stability, are investigated. Limestone layers which are usually perpendicular to land slope, is the reason of increasing safety factor against landslide. In some regions, existence of water in superficial soil layers causes gradual failure or mud flowing. In this research, disturbance of draining water, caused by soil practices of road construction, leads to unstability and side slope sliding is also considered. Finally, shear stress to vertical stress ratio in drained and non-drained conditions are defined as [t/σ n]d ≥0.4 and [t/σ n]u ≥0.25 which can be used as quantitative criteria to forecast the occurrence of landslide.

Floodwater spreading is an efficient and appropriate method for the optimization of runoff utilization, particularly in arid and semiarid region. Besides the reduction of damage caused by the floodwater, this technique would also be useful in the artificial recharge of groundwater, rangeland rehabilitation, and desertification control. The objective of this study was to evaluate the physical and chemical characteristics of the sediments carried into the Moghar floodwater spreading system and the resulting problems. Samples of sediments and soils from different strips were taken and some of their physical and chemical properties, including texture, salinity, alkalinity and the amount of lime, nutrients and organic matter, were determined. Also, the infiltration rate was determined in both soils and sediments in different strips. The results show that more than 100000 tons of fine sediments have been deposited in the system as a result of four times flooding. The thickness of deposition varies from 91 cm in the first strip to 11 cm in the fifth one. Moving from the first to fifth strip, the amount of sand in the sediment decreases, whereas the clay content increases. Soils of the area contain excessively higher sand content but much lower silt and clay as compared to sediment. While the sediment deposited has no salinity and alkalinity problem, the natural soils of the area are highly saline and alkaline. Furthermore, in contrast to low fertility of the soils, deposited sediments have more organic matter as well as higher total N and available K. Nevertheless, the deposition of the fine materials in different strips of the system has caused a great reduction in the infiltration rate, even in the fifth strips with only 11 cm depth of deposit. It seems that a great portion of the water entered the system would be lost through evaporation if no measure is taken to reduce the floodwater turbidity. Deposition of a great deal of very fine sediments would also lead to reduction of system efficiency and lifetime.

The efficiency of different plot shape and sizes for estimation of forage production were compared in the semi-steppic grasslands at northeastern of Golestan province. The plot shapes were square, rectangular, and circle and plot sizes were 0.25, 0.50, 0.75, 1.0, and 1.25 m2. In the representative stand of grassland type along each of five systematic transects, 5 plots were selected randomly and the weight of clipped plots and time of clippings on the basis of life form and total forage production were estimated. In spite of significant differences between plot shapes, different sizes and the interactions of size and shapes were not significant. The highest efficiency gained based on the Wiegert's method that the optimal shape and size of plots were circle and 0.75 m2 respectively that can be recommenced for semi-steppic grasslands in most parts of Iran.

Chemical control is one of the most important strategies in Integrated Pest Management (IPM). Studies on the chemical control with emphasis on effectiveness of emulsifiabl oil on dormant oilve psylla, Euphyllura olivina costa, were carried out in Taromm-sofla region (Qazvin province) during 1996-1997.Emulsifiable oil (I and 2%), Azinphos methyl 0/002 alone and with oil 1%, Etrimfos 0/001/5 without and with oil 1% and control treatment with 3 replications were tested in a Randomized Complete Block Design. Results showed that emulsifiable oil 2% for its stability, less side effect on environment and natural enemies and economic aspects when that applied pre oviposition is preferred for control of olive psylla.

The effects of inter-and intra-row distances, and their interactions on vegetative and reproductive characteristics of three cotton cultivars under dryland farming conditions were studied at Karkandeh research Station of cotton, Kordkoy, Gorgan. The experiment was conducted in a randomized completely block design as split-split plots with four replications with cultivar as main plot, inter-row distance as sub plot and inter-row distance as sub-subplot. There were three cotton cultivars (Sahel, Siokra and Zeta-2) seeded at two row width (80 and 100 cm) and three intra-row distances (10, 20 and 30 cm). Results showed that Zeta-2 had more branches than other two cultivars. Also, the effect of intra-row space on measured characteristics was more than inter-row spaces so that monopidal and sympodial branch length, and the number of sympodial branches per monopodial and main stem decreased as intra-row distance decreased from 30 to 20 cm whereas, decreasing row width from 100 to 80 cm had no effect on measured parameters exceptionally the number of sympodial branches per monopodia. Inter-by intra row distance interactions showed that for Sahel cultivar as plant density increased, main stem height, monopodial branch length, sympodial branch number, the height of the highest boll and the diameter of the base of main stem decreased but for Siokra and Zeta-2 only monopodial branch length and sympodial branch number decreased in higher plant densities. Based on the above cited results appears in higher plant density inter-plant competition for water and nutrient uptake decreases plant canopy extension, and sequentially plant size.

Inheritance of stem colour was studied using JG62 with purple stem colour (pigmentation) and ICCV2 with green stem color. The objective of this study was to determine the mode of inheritance of stem colour in chickpea. The studied were carried out during the Rabi season 1998-1999 and 1999-2000 at the International Crop Research Institute for the Semi-Arid Tropic (ICRISAT). Patancheru near Hyderabad A.P. 502 324, India. The experimental material comprised of parents, F1, F2, BC1P1, BC1P2 generations and 126 RILs. The F2 population of this cross segregated into 3: pigmentation 1: non-pigmentation. The results for RILs and BC1P1 showed a good fit to the expected 1:1 for pigmentation and non-pigmentation. The F3 population exhabited 1:2:1 ratio for pigmentation, segregated and non-pigmentation stem colour. All stems for F1 and BC1P2 were purple. The results of the present study revealed the stem color is controlled by single gene (B) and pigmentation is dominant to non-pigmentation.

In order to study the effects of planting date on yield and yield components of three cotton cultivars, an experiment was conducted in 2000 at Research station of cotton, Gorgan, Hashem-Abad. Three cotton cultivars, Sahel, Siokra and Delta-pain were compared in a randomized complete block design with four replications as split plot experiment in four planting date (24 April, 9 and 25 May and 9 June). Delayed planting date became the cause of decreased of yield, number of boil in plant, weight of boil and weight of 100-seed. Yield of second planting date as compared with first planting date, the third planting date as compared with first and fourth planting date as compared with first planting decreased 16, 24 and 43 percent with delaying planting date, respectively. In lieu of, each day of delayed planting date from the 24th of April till the 9th of June the yield of Sahel 50 kg in hectare, Siokra 24 kg in hectare and Delta-pain 42 kg in hectare decreased, respectively. Among the yield components the number of boil had high correlation with yield. The Siokra had the highest yield in hectare by including the most boil in plant. With delayed planting date, the number of boil in plant decreased. Among the cultivars, Siokra had the least weight of boil as compared with two other cultivars. But the relative sensitiveness of the Siokra weight of boil to the planting date was less than two other cultivars. The results of this research indicate that higher yield for desired acquisition obtain at 24 April and in delayed planting dates Siokra produces higher yield as compared with two other cultivars. In other words, Siokra adapts itself better with the conditions of different environments and produces higher yield as compared with two other cultivars in delayed planting dates.

The main crop in Iran and many other countries is wheat that indicated high genetic variation between varieties related to salt tolerance. In order to evaluation of salt effects on growth and Na+ and K+ accumulation, nine varieties and lines were compared with Zagros and Tajan (local varieties). The plants were grown in hydroponics culture solution in growth chamber under control condition. The most tolerant varieties were Milan, Opata/Bow, Pego/Seri and Tan/Pwe//Sara where indicated about 55 percent reduction in dry weight. On the contrary, the most sensitive varieties were Rayan, Zagros and Atilla"s'' Arvand where indicated about 75 percent reduction in dry weight. The leaf area indicated similar pattern to dry weight. The Na+ content was lower in Milan, and Tan/Pwe//Sara varieties in compare to Opata/Bow, Pego/Seri varieties, but most of Na+ accumulate in roots of Opata/Bow, Pego/Seri varieties. Salt sensitive varieties accumulated higher Na+ concentration. The K+ concentration reduced with higher rate in salt sensitive varieties like Rayan and Zagros in compare to Opata/Bow, Pego/Seri varieties. The results indicated the higher salt tolerance in Opata/Bow and Pego/Seri varieties. Further experiments in field are necessary for confirmation of this result.

In order to use gated pipes efficiently, it is required to know the hydraulic properties of the gated pipe and its gates. The hydraulic properties of gated pipe's gates were studied. The manufacturing quality and the discharge similarity of gates were evaluated by computing values of indices including Cv, qvar and Range. Results indicate that the manufacturing quality of gates is acceptable and their hydraulic performance's is similar.Therefore, an equation was developed to relate gate discharge to the hydraulic head behind the gate and the gate degree of opening. The gate discharge was computed under various conditions of pressure head and degree of opening with the equation derived and compared with measured values. The computed values of gate discharge were close enough to the actual values for practical purposes. A computer program was developed to simulate gate discharges along a gated pipe. The program calculates gate discharge and pressure behind the gates along a gated pipe line based on known values of pipe slope, length of pipe, gate degree or opening, gate spacing, pipe inlet pressure or discharge of last gate on the pipe line, distance from the pipe inlet to the first open gate, and numbers of open and closed gates at the beginning of the pipe.

High income of citrus has made a great attraction to extend citrus gardens with drip systems without caring to water scarcity particularly in arid and semi arid regions. Although drip systems in the studied region because of water limitation and importance of citrus are very popular, evaluation shows that some gardens are over irrigated while some others suffer from insufficient irrigation. For more evaluation, real water. Requirement and water consumed by irrigation in a number of gardens and also the relation between age and water requirement of citrus in more than 50 gardens with the age of 1 to 30 years were studied. Results indicated the management and evaluation of drip systems, with increasing the technical knowledge of farmers are very essential. The systems without clogging problems with sufficient pressure are over-irrigated while the systems which suffer from clogging and their pressure are not sufficient are not irrigated sufficiently. For example, in some evaluated gardens the volume of irrigation was measured as 21097, 11252, 16802, 14721, 498, 5648 and 10552 cubic meter per hectare while real water requirement base on modified Hargreave-Samani equation was estimated as 16470, 8680, 14160, 11647, 5590, 12990 and 13450 cubic meter per hectare, respectively.

Soil tillage of irrigated fields is usually being performed by moldboard plow. In this study the effect of different speeds and plowing depths on the performance of moldboard plow was evaluated. The soil was silty clay with 14%-16% moisture content. The performance parameters studied were draft, specific draft, drawbar power, and soil inversion. A randomized complete block design was used for statistical analysis of data. 9 treatments representing different levels of speed and plowing depth were replicated 3 times. It was found that draft, specific draft, and drawbar power, increased as the forward speed and plowing depth increased. It was also found that the increase of forward speed and depth of plowing improved the quality and quantity of soil inversion. It is recommended that plowing speed for an economical seedbed preparation should be 3.5-4.5 Km/h. Since power requirement was directly proportional to the plowing depth, from economical standpoint, it is recommended that plowing depth should be determined on the basis of crop root requirement, for those crops with shallow roots a shallow plowing may be sufficient.

197 juvenile Acipenser persicus and A.guldenstaedti specimens were collected in the southeast of Caspian Sea during 1997-1999 from beach seines in Minankaleh Peninsula, Golestan Province, Iran. Specimens fixed in 10% formalin and transferred to laboratory, examined by standard methods. Stomach contents determined, possibility and frequency of i prey calculated with standard methods. The percent of empty stomach, prey dominance, resultant index food niches and the cached prey diversity evaluated by specific formula. Results showed that in A.guldenstaedti gammarids and in A.persicus cumacea were the dominant and specific food items. Seasonal changes were observed in food compositions. The percent of empty stomach in two species in autumn and winter were higher and lower respectively in comparison with other seasons. In all seasons the percent of empty alimentary canal in A. guldenstaedti were higher than A.persicus. The food niche width of A.guldenstaedti was less than A. persicus in caught preys. In food overlap, as observed was in the order of highest in winter and lowest in the spring.

The data of 118 male lambs with average age of 135 days and 58 carcasses Lori- Bakhtiari male lambs were used to determine effect of the length of fattening period on growth and carcass characteristics. Lambs were weaned at 90±5 days of age. They were fed ad libitum for 60, 80 or 100 days. At the end of fattening period of each level of treatment 18, 20 and 20 lambs were randomly selected and slaughtered, respectively. Due to the unequal number of observation in the subclasses, data were analyzed by the least-squares procedure. The length of fattening period had highly significant effect on final weight, but did not influence on daily weight gain. Age of dam and type of birth had not any significant effect on final weight and daily weight gain. Initial weight of single lambs was significantly higher than twin lambs. The effect of dam age on initial weight was significant. Lambs, which were slaughtered after fattening period 60 days, had significantly lighter carcass, meat and bone weight as compared to those that were fattening for 80 or 100 days. The means for cuts weights of shoulder, back, leg and flank+brisket were significantly higher among the lambs which slaughtered after 80 days in fattening period compared with those which were feedlot for 60 days, but between lambs which were slaughtered after 80 and 100 days had not significant different. In conclusion, due to final weight, meat weight, carcass cuts weights and not any significant increase for fat-tail, 80 days length of fattening period for Lori-Bakhtiari are recommending.

Variance components, direct and maternal heritability and c2 in Baluchi sheep were estimated by restricted maximum likelihood procedure using 25 years data collected in Abbas abad station (Korasan Province). Six different animal models were fitted. These models were different for the number of random effects. The results of six models were compared. Estimates of direct heritability for birth, 3, 6, 9 and 12 moths weights obtained by model eight were 0.19±0.019, 0.13±0.031, 0.16±028, 0.12±0.42 and 0.26±0.044 respectively. The maternal heritability and C2 were estimated to be (0.08±0.017) and (0.12±0.012), (0.04±0.021 and 0.07±0.081), (0.03±0.019 and 0.02±0.017), (0.03±0.025 and 0.03±0.024) and (0.01±0.012 and 0.01±0.013), respectively.

An experiment was carried out to estimate the potential activity of rumen anaerobic fungi in production of zaylanase enzyme on different substrates. Samples of wheat straw, barley straw, wheat straw+urea, rice straw, wheat straw+molasses, wheat bran, bagasses (sugar cane), cotton seed, alfalfa and corn silage were used as the substrate to culture rumen fungi which isolated from a fistulated Shal sheep. Zaylanase enzyme activities of samples were measured after 0, 3, 6 and 9 days of incubation. Production of zaylanase enzyme of substrates varied from 4.97 to 14.78 (unit enzyme) after 9 days of fungi growth. The highest and lowest production enzyme was related to wheat bran and barley straw, respectively. Enzyme production was increased sharply until 6 days of fungal incubation and continued slowly by 9th day in all of the cultures. The results indicated that rumen anaerobic fungi have the ability for enzyme production.

The present study was carried out to survey the effect of moderate deficiency of methionine on growth performance, carcass characteristics, and nitrogen efficiency of utilization of broiler chicks. In the growth study, male broilers were used in 16 floor pens. The chicks received the experimental diets from 1 to 42 days of age. All chicks were fed a commercial finishing diet from 42 to 49 days of age. The dietary treatments consisted of a methionine-deficient, basal diet and three further methionine-supplemented diets, which met 50, 75, and 100 percent of the deficiency of sulfur amino acid (SAA) requirements of the basal diet. The latest satisfied the requirement of SAA advocated by NRC (1994). Cystine met NRC (1994) recommendation with all diets. In balance study, the same dietary treatments as the growth study were used in cages. The experimental diets were fed from 10 to 17 days of age. Methionine supplementation of the basal diet improved weight gain and feed conversion ratio (P<0.05). Low methionine reduced proportions of skinless, boneless breast meat at 49d. Compared with methionine-supplemented diets, the methionine-deficient diet caused increased abdominal fat pad, decreased N retention and increased uric acid excretion.

An experiment was conducted to evaluate the effects of different N levels on yield and yield Component of three forage sorghum cultivars. Three sorghum cultivars viz: Speed feed, Jumbo, and a native strain (Syahzan) were treated by 0, 50, 75, and 100 Kg/ha N fertilizer and compared in Complete Randomized Block Design With three replications.During the vegetative and generative growth period plant growth characteristic such as stemming, budding, plant height, stem and leaf dry matter and number of tillers were recorded. To investigate the growth index, the plant dry matter and leaf area was measured in few stages of plant growth. Nitrogen levels had a significant effect yield and growth index of sorghum (P<0.05). Nitrogen application of 100 Kg/ha produced the highest forage dry matter as well as silage production. The plant, leaf and stem dry matter were the highest at 100 kg/ha nitrogen level.