مجله بین المللی علوم و فناوری کشاورزی
سال:1384 | دوره: | شماره: |تعداد مقالات:8

The primary purpose of this study was to assess the professional satisfaction of Rural Production Cooperative (RPC) members. The secondary purpose was to investigate the professional characteristics of RPCs' farmers, and determine the RPC members' attitudes toward cooperative farming. The population of this study consisted of all 2000 rice-growing members of four RPCs in rural Mazandaran, a northern province of Iran. Using a complete randomized sampling technique, 320 members of the population were selected for the study. A questionnaire consisting of three parts was designed to collect the data needed for the study. The results showed that cooperative farming substantially increased farmers’ crop yields and lowered their farm operational and maintenance costs. Members reported particular savings in the area of farm labor expenses. More than 90% of the farmers indicated that cooperatives enabled them to have more access to agricultural ma-chinery, which resulted in the efficient use of farm resources. About 64% of the farmers were considered to be practicing a “high” level of mechanization on their rice fields. The members generally had a positive and favorable attitude towards the cooperative and its activities. The mean score on staff professional satisfaction was 2.4 (2= somewhat satisfied; 3=Satisfied), with a standard deviation of 1.6. There was a statistically significant relationship between members’ professional satisfaction and their attitude towards the co-operative (r=0.645). This is considered as a “substantial association”. A Multivariate Linear Regression indicated that among the independent variables, the farmers’ level of participation in the cooperative’s activities, their attitude towards the cooperative, and the amount of land owned by farmers could together explain 68.8% of the variability in members’ professional satisfaction. This implied that there are other factors that may have contributed substantially to the variations in farmers’ professional satisfaction that were not investigated in this study.

Common carp is infected by five Dactylogyrus spp in both pond and natural lake habitats in Iran, namely D. extensus D. anchoratus, D. achmerovi, D. vastator and D. sahuensis. Fry and fingerlings are more sensitive to infection and their sensitivity is increased with the higher density of fishes usually found in ponds. General gill lesions in dactylogyrosis are quite similar but there are few differences in local lesions among Dactylogyrus spp infecting common carp. In this paper, the geographical distribution of Dactylogyrus spp of common carp is presented and the gill histopathology caused by D. sahuensis is described and discussed.

The present study aims at applying different methods for predicting spring inflow to the Amir Kabir reservoir in the Karaj river watershed, located to the northwest of Tehran (Iran). Three different methods, artificial neural network (ANN), ARIMA time series and regression analysis between some hydroclimatological data and inflow, were used to predict the spring inflow. The spring inflow accounts for almost 60 percent of annual inflow to the reservoir. Twenty five years of observed data were used to train or calibrate the models and five years were applied for testing. The performances of models were compared and the ANN model was found to model the flows better. Thus, ANN can be an effective tool for reservoir inflow forecasting in the Amir Kabir reservoir using snowmelt equivalent data.

Two strains -425 and Y87/47- of Alfalfa mosaic virus (AMV) were propagated in and purified from Nicotiana tabacum cv. Samsun NN. Thirty-three AMV specific monoclonal antibodies (MAbs) from two fusions were raised against strain 425. These antibodies were of isotypes IgG1 and IgM. MAbs recognised three types of epitope. Group I did not react with the virus particle surface or viral coat protein of two strains in PTA-ELISA, but they reacted with a 30-kDa structural coat protein of AMV by immunoblot analysis only and were able to recognise cryptotopes. Group II reacted with metatopes of both strains in PTA-ELISA. Group III reacted with a 30-kDa structural coat protein of AMV by immunoblot analysis and in PTA-ELISA for the Y87/47 strain only. Immunoblocking experiments in which suspensions of purified AMV and MAb were offered between parafilm membranes for acquisition by Myzus persicae revealed that MAb-2 was effective in blocking (inhibiting) transmission. This result suggests that the epitope which was localised by MAb-2 plays a role in the aphid transmission of AMV.

The effects of total carbohydrate, total protein, carbohydrate/protein ratio, amino acid contents, initial pH and aeration on biomass yield product of Bacillus thuringiensis subsp. kurstaki was investigated. The bacteria were cultured in economical media comprising agricultural products and by-products including fishmeal, cottonseed meal, defatted soybean meal, cornsteep liquor, yeast extract, scotafeme, sorghum and peptone as protein sources and glucose and beet molasses as carbohydrate sources. The results indicated the presence of a direct correlation between yield biomass and carbohydrate/protein (C/N) ratio as well as the glutamic acid content of the media. The highest biomass was produced in the media providing 0.4 – 0.5 C/N ratio and 13.9% glutamic acid. A pH range of 7.0 to 8.0 was needed for high yield production. The optimal ratio for culture volume to flask size and shaking speed were 1/5 and 250 rpm, respectively. The biochemical factors described can be considered as the minimal criteria to evaluate culture media for biomass production from Bacillus thuringiensis subsp. kurstaki.

The nucleotide sequences of 28S nuclear rDNA were determined for 34 powdery mildew taxa mostly collected from Iran in order to infer the phylogenetic relationships of these fungi. Total DNA was isolated from cleistothecia or mycelia using the chelex method. About a 650 nucleotide length of the 5´end of the 28S rDNA was amplified twice by the PCR using a nested primer set, PM3, TW14 and NLP2. Direct sequencing of the PCR product was done in an Applied Biosystems 373A sequencer. The results showed that powdery mildew taxa are divided into five groups, which were distinguished by their morphology. Members of Erysiphe section Erysiphe, Microsphaera and Uncinula clustered together. E. sect. Galeopsidis and E. sect. Golovinomyces were seperated from E. sect. Erysiphe and formed the Euoidium without fibrosin bodies group. Leveillula and Phyllactinia showed a close evolutionary relationship and clustered together. The genera Cystotheca, Podosphaera, Sawadaea, and Sphaerotheca formed a monophyletic group (fibrosin body lineage) with 98% bootstrap support. These fungi are well characterized by the presence of fibrosin bodies in their conidia. Blumeria graminis, which is characterized by some unique morphological characters, clustered with fibrosin body lineage with a low bootstrap value. This result shows that B. graminis is not closely related to the Erysiphe species. The nucleotide divergence between the genera analyzed in this study ranged from 0.50 to 14.10%. The lowest nucleotide divergence was found between Microsphaera and E. sect. Erysiphe (0.50–4.50%). Podosphaera and Sphaerotheca showed a low level of divergence, too (2.30-2.60%), which suggests a close relationship between these two genera.

Long term sugarcane cultivation can alter soil physical properties. The objective of this study was to determine the effects of 38 years of sugarcane (Sacchrum officinarum L.) cultivation on the physical properties of fine textured soils (Haplustepts and Calciustepts) in southwestern Iran. Six paired soil profiles (three pairs in each soil type) were dug along parallel transects (100 m apart) in a side-by-side comparison of areas cultivated and uncultivated with sugarcane. Composite and undisturbed soil samples from 0-30, 30-60 and 60-90 cm layers were taken for physical and chemical analysis. The results of this study revealed that long term sugarcane cultivation resulted in a higher bulk density, lower structural stability, and an increased proportion of fine pores. The decreased number of macropores together with decreased structural stability indicated the formation of a dense compacted layer at 30-60 cm in sugarcane cultivated soils.

A proper and an accurate evaluation of sediment concentration are required for managers and planners for the suitable and effective design of hydraulic structures. The design of most of the soil and water conservation structures is made inaccurately, since the number of studies conducted in the field of sediment temporal distribution is limited. The problem mentioned above is particularly exaggerated in developing countries where more effort is needed in research to achieve appropriate solutions for problems encountered. The main objective of conducting the present research was to develop a model through which the temporal distribution of the watershed sediment i.e. the sediment graph during a storm event can be estimated. The model was developed on the basis of the easily accessible hydrological data of the Amameh watershed in Iran comprising an area of 3712 ha. A water discharge rating curve, precipitation-runoff relationship and sediment rating curves were developed for the watershed study for the completion and refinement of the collected hydrological data. From the Sediment Rating Curve (SRC), it was observed that in most of the cases there was more than one value of sediment discharge for the same value of runoff discharge located at the rising and falling limbs of the hydrograph. Therefore, the development of two separate regression equations for these sets of points was attempted by using regression and confidence area ellipse approaches. The approach based on the hydrological data was then used for the development of a storm-wise temporal distribution prediction model for sediment yield. Based on the results of factorial scoring, it was found that the model developed on the basis of the concept of Unit Sediment Graph and convolution into direct sediment graph using the sediment mobilized could be supposed as an acceptable performed model for the prediction of the sediment graph in the study watershed.