مجله اقتصاد و توسعه کشاورزی
سال بیست و دوم شماره 1 (پیاپی 2، زمستان 1386)

More than %90 of natural silk in world is produced by means of mulberry silkworm (Bombyx mori L.). Therefore, it is important that we recognize and collect mulberry varieties which have high quantity and quality leaf performance. For this purpose, an experiment was conducted with five mulberry varieties (Kenmochi, Kairyonase, Ichinose, Shinichinose and Local varieties) during two seasons(spring and late autumn) in Iranian silkworm research center. After recording, obtained biological and economical characters, data (such as larval duration, larval nutrition duration, larval mortality, number of cocoon, best cocoon weight, best cocoon shell weight, shell cocoon percentage, etc.) were analyzed using a complete randomized design (CRD) model with factorial arrangement including ten treatments with three replications by means of IRRISTAT statistical software. The ANOVA results showed that type of mulberry varieties and rearing seasons have significant effects on silkworm yield

In this study, effect of insurance on chemical inputs utilization (environmental effects of insurance) is surveyed. Data of this research collected by using stratified random sampling method and interview with 150 wheat producers (insured and non-insured) of North Khorasan province in 2004. Results showed that education, size of family, farm ownership, land fragmentation, participation in extension classes, land cultivated and risk aversion have positive effect and age of farmer and premium receipts have negative effect on insurance demand. Probability of insurance adoption by wheat producers causes decreasing of poison and chemical fertilizer and so increasing of environmental benefits. Regard to results, attempt for insurance coverage all wheat farmers, training on chemical inputs utilization and targeting of target groups orientated to insurance suggestied.

Agricultural sector is the most important sectors in the country which has a large share in total employment. The increasing supply of labor because population growth and low capacity of production cause the country with high rate of unemployment. Therefore, stand with this crisis is one of the most important works of government. In this study using Artificial Neural Network, the employment is forecasted by 1958-2004 data for 14 years later and results show that the trend of employment in agricultural sector in later years first is diminished and then increased.

According to considerable wight of pistachio in non-oil export of Iran, the production and export advantage of this product are estimated using indices like scale, efficiency, integrated, revealed and symmetric revealed advantage as well as their growth for the period of 1990 – 2005. Results show that scale advantage index for Iran is much higher than its rivals while Syria and Turkey had the highest efficiency advantage and highest efficiency advantage growth, respectively. Highest integrated advantage and highest growth of this index belonged to Iran and Italy, respectively. Despite Iran's advantage in pistachio export, its growth is negative for the studying period (- 44.05 percent) while competitors had positive growth. A decline, for any reason, in exporting advantage of Iran's pistachio would lead an increase in rival's advantages and their market share. Statistics show that the policies carried out during the Third Development Program were successful in improving production efficiency and penetrating into world markets. Policy making in the direction of reducing production costs, improving commodity quality and using suitable processing method will cause sustainable and successful presence in world markets.

Consumer rational behavior is the first and basic presumption for representation and development of economic theories and relations in field of consumer behavior. For the most part investigations related to demand function, the estimation results is correct while demand function and implied utility be a good estimations of real utility and demand functions. This is not a testable hypothesis. Then, should be prove accuracy of rational behavior hypothesis. There exists only one method to investigate accuracy of rational behavior hypothesis and this is revealed preference. Used data in this study is monthly price and consumption quantity of vegetable oil that is mustered from Refah Chain Stores during 3 years (2004-2006). Test results indicated existence of 13 violations that did not rectify using generalized Afriat index and using graphical methodology of de Peretti, whole of period divided to two sub period, April 2004 to December 2005, and, January 2005 to February 2006, without any violations. Rupture in utility function is appeared as consumption reduction in more of studied rigid vegetable oils and approximate stability in liquid oils consumption. Thus, it could be prospected consumption reduction of vegetable oil in Iranian households by continuous medical and publicity policies about consumption detriments of vegetable oil.

The purpose of the present study was to investigate and analyze the influence of water users’ cooperative (WUC) on farmers’ attitudes toward optimum agricultural water management practices with an approach to compare the two groups of farmers in irrigation networks with WUC and without it. The research method was a descriptive-correlational and causal-comparative study of the survey type. The target population in the study was the entire farmers of irrigation networks in Khorasan-Razavi Province. Using stratified random sampling technique, 335 participants were selected as a statistical. The content and face validity of the questionnaire was specified after several times of review and correction by the faculty members at Tarbiat Modarres University and the executive experts of Agricultural Jihad Organization and Regional Water Joint-stock Company in Khorasan-Razavi Province. The reliability analysis was conducted and Cronbach’s alpha values for the various sections of instrument were estimated to be between 0.73 and 0.86. The results of descriptive findings showed that attitude rate more than half of studied farmers (55.1%) regarding agricultural water management were at positive relatively and positive levels. Moreover, the results from statistical analyses indicated that WUC was very effective on the development of factors related to the social, human, physical, financial, and natural capitals, so that the WUC irrigation network with increases in the components of social confidence, solidarity, and participation, improved extension contacts, developed appropriate information channels, improved the status of regional irrigation system, and increased water users’ participation in irrigation water management were more effective on farmers’ attitudes toward the development and application of agricultural water management strategies such as under-pressure irrigation technology compared to non-WUC irrigation networks.

Replacement of tractor is one of the important decisions that must be made with respect to farm machinery manager. Accurate forecasting of repair and maintenance cost is one of the most critical factors for making this decision. The purpose of this research was to evaluate the capability of two structures of MLP neural network in predicting repair and maintenance costs. First, networks were designed in order to predict the components of repair and maintenance costs individually, and then a single network was designed for simultaneous prediction of all components costs. The study was conducted using actual data on 28 John Deer tractors from Astan Ghodse Razavi agro-industry. According to the obtained results, the two types of neural networks are accurately able to predict the repair and maintenance costs. Also, the prediction of repair and maintenance cost components of tractor with a single network produces a better result than using separate networks for prediction of each cost component. Therefore, neural network can be improved the economic decision making capabilities of machinery managers.