JOURNAL OF AGRICULTURE
Year:2008 | Volume:10 | Issue:2|Papers Count:21

Biological studies of Helicella candeharica in citrus orchards in west of Mazandaran province (Tonekabon region) was conducted during 2004-2005. This species has one generation in a year and mating and egg laying were lasted from August to September. Under natural conditions of Tonekabon, the snail showed to hibernate as larvae and adult at the depth of 2.5-3 cm in the soil. Larvae and adults were appeared in early spring time and were completed after four months. Mean of oviposition period was 25 (±3) days, average egg cluster was 31.3 (±5) eggs means duration of incubation period was 25 (±4.85) days. The hatchability of eggs was 65.5 (±15) percent. A mean number of 24 (±7) newly hatched snails was counted per adult. In early autumn, newly hatched snails and adults damaged the leaves and citrus fruits. The animal entered the winter season in the form of hibernation (below 8oC) and in summer due to high temperature (above the 23oC) caused aestivation. The snail abundance has a direct relation with the humidity and temperature. The range of temperature that snails were active was 8-23oC in Tonekabon locality.

The main purpose of this descriptive – survey research was to study extension experts’ attitudes about effective factors in consumption of organic products and in Iran. The main population consisted of 1200 extension experts in Iran. 289 samples of extension experts’ were selected through randomized sampling to answer the questionnaire. The validity was cheked by a panel of agricultural extension experts the university of Tehran. Reliability was measured by Cronbach's -alpha formula and <=0.92 showed the reliability of the questionnaire was acceptable. SPSS Win Software was used for data analyzing, and factor analysis method was employed in this research. According to the results the main communicative channel was TV and radio and the main supply method was labeled organic products in the markets. The results of factor analysis showed that effective factors explained 59.17 percent of the whole variance. In conclusion, four factors extracted, the first factor was educational – supportive, as the first factor, broadcasting, constructive institutional and infrastructure factors. Also the result of t-test showed that was not different between women and men attitudes.

The main purpose of this descriptive–survey research was to analysis of improvement mechanism of wheat consultant engineers' project in Isfahan Province. The main population consisted of 87 extension experts’ and 164 of WCEs in Isfahan province and through randomized sampling 55 samples of extension experts’ and 95 of WCEs were selected to answer the questionnaires. The validity of questionnaires was cheeked by a panel of agricultural extension experts the university of Tehran. Reliability was measured by Cronbach's - alpha (<=0.83 and <=0.75) showed the reliability of the questionnaire was acceptable. SPSS/win software was used for data analyzing, and factor analysis method was employed in this research. According to the results, the main improving mechanism were facilities, transport of WCEs and background for self employment. The result of factor analysis showed that improvement mechanism as view of WCEs was logistic, communication, performance, situation and selecting. And as view of extension expert were motivation, selection, participation, logistic and performance.

On the basis of acreage, production and import amounts, maize is one of the strategic products in Iran, Regarding defects of marketing system of maize, in this analysis using yearly observations between 1368 to 1385 (18 years) and Eviews software, the marketing and econometric model of maize marketing margin was studied. The results show that the most important factor in the maize marketing margin is its wholesale price. Therefore, price policies are governmental effective policies on the maize marketing margin, consequently it is necessary that for making marketing margin equitable is done the necessary. Also the efficiency of maize marketing system is not suitable and this has led to the increase of maize marketing margin. So, establishment of cooperatives of crops production and distribution (consisting farmers, wholesalers and brokers), presentation of the whole imported maize by private sector and produced maize in the country by exchange are recommended.

Cattle manure is made from liquid and solid waste. It contains the straw and stubble that is used for the cattle bed. Density of the cattle manure is inherently low, which is difficult and costly to transport. Pelleting is one method to solve this problem. The physical properties of the pelleted cattle manure was investigated in this study. The results showed that by increasing moisture content of the pellets from six to 20 percent, the bulk density of the pellets decreased from 660 to 630 kg/m3 and the particle density of the pellets increased from 1095 to 1583 kg/m3. The force required to rupture the pellets decreased from 61.3 kg at six percent moisture content to 19 kg at 20.0 percent moisture content. Durability of the pellets was variable from 34 to 53 percent in the range of moisture content and was maximum at 10 percent moisture content. The pellets could absorb a maximum of 8 percent moisture during 24 hours from air with 80 percent relative humidity.

Systemized sabbatical leaves seem as an appropriate mechanism for fostering academic collaboration, improving academic capacities and developing professional capacity of faculty members in higher agricultural education system. This research was done with aim to identify and analysis expected outcomes and impacts of sabbatical leaves for professional development of agricultural faculty members. Methodologically, this research was carried out based on survey strategy. The population of this research consisted of all faculty members of public agricultural faculties and colleges of Ministry of Scientific, Research and Technology (N=1260). Using randomized stratified sampling method, 165 faculty members were selected. A questionnaire was used as research tool in order to collect data. Face and content validity of the questionnaire were established using comments of a group of faculty members. According to calculate Cronbach's alpha (0.79) reliability of the questionnaire was confirmed. Using SPSS 11.5 collected data was analyzed. Based on calculated coefficient of variations expected outcomes and impacts of sabbatical leaves were prioritized in accordance with findings of factor analyzing the expected outcomes and impacts of sabbatical leaves of faculty members, six components were extracted including, fostering educational collaboration and scientific exchanges, research outcomes, personal outcomes , strengthening professional communication, developing academic cosmopolite and professional outcomes. These factors explains multiplicity of outcomes and impacts of sabbatical leaves and respectively explained 22.033, 18.744, 14.225, 10.907, 10.320 and 7.077 of the total variances (totally, explained 83% of variances). Based on inferences of these research findings some mechanisms were suggested for institutional systemizing the sabbatical leaves of faculty members in higher agricultural education.

The population consisted of 2202 students of College of Agriculture and Natural Resources, University of Tehran Karaj. 118 of students were selected by stratified random sampling. A questionnaire was developed to gather required data. The content validity of the questionnaire was established by faculty members at Department of agricultural extension and education, University of Tehran. A pilot study was conducted to establish reliability of the instrument via agricultural students. Cronbach alpha's coefficients for the main scales of the questionnaire was higher than 0.75. Results of factor analysis showed that the components were classified into four factors of: trainer - teaching method, educational goal - content, educational space- facilities and educational management. These four factors explained about 74.2 percent of the variance of data.

In order to comparison of weeds mechanical control for sugar beet, A rotary cultivator was designed and constructed in first year, and compared with other mechanical control in second year. Five treatments, included: Rotary hoe cultivator, Furrower cultivator, Rotary cultivator, No weeding and manual weeding were compared. Experiment design was Random Complete Blocks Design (RCBD) with three replications. There was not any significant difference between treatment aspects of weeds frequency before weeding in level five percent also there wasn't any significant different between Manual weeding and Rotary cultivator treatment inspect of weeding efficiency after weeds control. There was significant different between Furrower and Rotary hoe cultivators in aspect of weeding efficiency after controlling of weeds. Average field capacity for cultivators was 0.75 ha/h. In aspect of economical considerations, Furrower cultivator and manual weeding had the highest and least final efficiency respectively. So, treatments were ranked from Furrower cultivator, Rotary cultivator, Rotary hoe cultivator and Manual weeding respectively.

A new mechanical cultivator was proposed for mechanical weeding in part one. The precise point method was used to geometric design of this new cultivator. The aim of this research is selecting the suitable mechanism of the studied mechanisms in part one. The velocity and acceleration of links (kinematic) is the base of dynamic analysis of the systems. The variation of velocity, acceleration and jerk as the kinematic parameters as well as the joint forces and input torque as the dynamic parameters were investigated. Programming in Matlab was used to solve the equations and draw the diagrams. The program is provided to calculate the values of angular velocity, angular acceleration, angular jerk, joint forces and required input torque of the mechanism and draw the diagrams. The output diagrams showed that the values of the angular acceleration and jerk of the links and the values of the forces of the mechanism's joints were continues. By considering the values of the forces at joints and links of the mechanism the type of the material and sectional area can be calculated. The value of required input torque was obtained by considering maximum values of the related diagram.

Moisture sorption isotherms are useful in food dehydration, storage and packaging. Because of the complex food composition, experimental measurements are necessary for prediction of the isotherms. Moisture sorption isotherms of Thompson seedless raisins were determined at 30, 40, 50, 60, 70 and 80oC, using the standard static gravimetric method developed by the European cooperation project COST 90. GAB, Smith, Oswin, Halsey, Henderson and Arcy-Watt equations were fitted to the experimental data. The experimental data were fitted well with D’Arcy-Watt equation at 30 to 70 and with GAB equation at 80ºC. The Isosteric heat of sorption was determined (4.79) kj/mol.

The statistical population of this study was agricultural extension agents. Sampling method was stratified random sampling and Questionnaire used as research instrument, its validity achieved by a group of experts of ICTS and agricultural extension and education and reliability was 0.76 that was estimated by Cronbach’s alpha. Extension agents with scores lower than 47 considered in negative attitude group between 47-74 classified in neutral and more than 74 categorized in positive attitude group. The relationship between age and level of education with attitude towards ICTs was not significant but there was positive and significant relationship between attitude and using ICTs. The results of factor analysis showed that four factors (Improving extension efficiency, environmental-organizational, quality of content and economic cost-effectiveness) explained 55.5 percent of total variance of attitude towards using ICTs in agricultural extension.

Striped rice stem borer, Chilo suppressalis (Lepidoptera: Pyralidae) is one of the major pests in north part of Iran which causes serious damage. The last larval instar overwinters in the stem of weeds around the fields. Regarding the importance of weeds as overwintering habitat, population density of larvae was studied in three areas, low-, mid-, and up-lands of Mazandaran province and also on three host weeds: Xanthium pensylvanicum, Sorghum halopense, and Amaranthus retroflexus. The results imply on the highest density of larvae in the mid- and up-lands areas and its preference to locate in X. pensylvanicum for overwintering. There was no significant difference between the two other hosts. Results of population fluctuation showed that it had a low increasing of population from October to December, therefore the lowest density was observed in early October and the highest in late December. Results of interaction effect of area × hosts on population density indicated that the highest density located on X. pensylvanicum in the mid- and up-lands areas, and the lowest density on A. retroflexus in low-land part. Based on the results, removing the most important weed which are overwintering habitat for larve from around the rice fields will be resulted to increasing the larval mortality through winter, and therefore decreasing pest population density in crop season.

The rice fields consist of diverse fauna of Arthropoda because of both subterranean and aquatic ecosystems. In this research, the fauna of predator beetles including Carabidae, Coccinellidae, Staphylinidae, Malachiidae, and their population fluctuation were studied in Mazandaran province during 2002-2006. A number of 13 carabid species, one staphylinid species, six coccinellid species, and two species of Malachiidae were collected from different rice fields of Mazandaran. Out of wich, 10 carabid and two malachiid species are new records for Iranian fauna. The density of these beneficial beetles increase since May until July and the highest density was obtained in the late of July. The highest density of predator beetles was observed on the rice variety of Fajr. The results of biomass-percent comparison between predator beetles with predator bugs (Heteroptera), spiders (Araneae) and other predators of rice fields indicated that the biomass-percentage were 38.2 (Coleoptera), 10.8 (Heteroptera), 26.2 (Araneae), and 24.9 (Others), respectively. Therefore, the predator beetles had the highest biomass-percent because of high density of Paederus fuscipes in all rice fields of Mazandaran.

In this research the activity of 75 producers, 55 wholesalers and 55 retailers, citrus market of Jahrom County was investigated. The results indicated that margin of wholesale, retail and total margin of citrus in this county was 1461.1, 1480.3, and 2941.4 Rs respectively. Share of producer from marginal price was estimated to be 57.9 percent and Share of wholesaler was more than retailer. In total in citrus market of Jahrom County, wholesale levels was caused increasing of market inefficiency and the most inefficiency channel for the carely price inefficiency, technical and total inefficiency was channel of producer- wholesale- customer and the best efficiency channel was producer- customer. The cost coefficient estimated and the marketing costs was 35.1 percent of citrus marginal price and With attention to estimating of total marginal function, with increasing one percent in retail price and marketing cost, Total margin increase 0.57 and 0.20 percent respectively.

The technical, allocative and economic efficiency of wheat growers in Baft, Kerman Province were studied to analyze the degree of farmers success in the optimun allocation of their resources and the possibilities of increasing the production based on the available resources and factors of production. Sampling was based on random method, so 75 farmers were selected. The stochastic frontier production and cost function methods were used to analyze technical, allocative and economical efficiency using spss and Front. 4 softwares. The result showed the average technical, allocative and economic efficiency in Baft are 88, 84 and 74 percent, respectively. The improper allocation of resources by farmers has decreased the economic efficiency compared to technical efficiency.

In this study the wavelet neural network (WNN) and artificial neural network (ANN) were used to simulate barley breakage percentage in combine harvester. The models have been trained using the same data conditions. Air temperature, thresher cylinder speed, distance between thresher cylinder and concave (back and forth) and the percentage of barely moisture were as the input variables. The results showed that the wavelet network (WNN, RASP 1) with 90.2% correlation coefficient for barely breakage would be an appropriate substitute for artificial neural network with 88% correlation coefficient. The result of sensitivity analysis showed that all input variables had a significant effect on barely breakage. Speed of thresher cylinder had the most effect and the degree of air temperature had the least effect on barely breakage.