مجله بین المللی علوم و فناوری کشاورزی
سال:1388 | دوره: | شماره: |تعداد مقالات:10

Gilan Province is among the most important regions of Iran for rice production. The general aim of this research is to determine the best variety of rice for planting, so that the minimum level for farmer's expected living gross margin can be provided. On the other hand, determining the best variety with regard to the risk in price is another aim of this research. To this end two risk models based on Telser and Kataoka linear programming were used. Data needed for seven understudy varieties in this research during 2000-2006 were connected from 7 representative farms at the Gilan Province level.Taking the related risk-rows to gross margin per hectare of the 7 varieties under study during the aforesaid years, and using the Kataoka model, the highest amount of living gross margin per hectare at different probability levels was calculated. On the other hand, through the Telser model the area under planting of optimized varieties over different probability levels, showing that the probability of the gross margin per hectare of rice farming is less than the highest amount of living gross margin, was calculated. The results showed that at different levels the gross margin of the aim, considering the probability constraints, the two items Hashemi and Ali Kazemi were the best ones for achieving the aforesaid goals.

This study investigated the factors influencing the decision to plant almonds in the Saman region of Chaharmahal - Bakhtiari Province in central Iran through conducting an economic survey in 2005. Using portfolio investment theory and econometric model estimation (Shively, 1998), this paper identifies the most important factors influencing the individual farmer’s decision concerning the number of almond trees planted during 1995 - 2004. Results of this study show that farm size, permission for water use, a one-year forecast of almond price changes, and the upcoming year’s expected change in the guaranteed price of wheat as a competitor crop in the use of land and water had a significant impact on the number of trees planted. This study indicates that policymakers should take notice of the adverse impact of the increasing wheat price trends on tree planting and indirectly promote more research on the environmental impact of almond plantations, particularly as it relates to soil erosion and environmental issues.

Field studies were conducted during the cotton crop seasons in 2003 and 2004 at CCS Haryana Agricultural University, Hisar, to identify mortality factors in the egg stage of Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae) in the insecticide-free cotton fields to gain an insight into the role of these factors in causing egg specific mortality.Eggs were collected from cotton fields on different dates during September-November and brought to the laboratory for determining egg viability and level of parasitism.Similarly, plant parts bearing eggs in the field were tagged on different dates and observed daily to assess egg loss. The correlation of egg loss with various abiotic factors was determined. The mean viability of field collected eggs were 75% and 89% during 2003 and 2004, respectively (pooled mean egg viability of 82%). It was 51.34-66.55 (Mean: 59.72) % in the case of eggs deposited in the field by the laboratory-reared females. Eggs were parasitized by Trichogramma chilonis Ishii during September-October and mean parasitization was 25 and only 1-2% during 2003 and 2004, respectively. There was a positive correlation of % egg loss with wind velocity and rainfall as evident for multiple correlation coefficient values, i.e. 0.92 and 0.60 for 2003 and 2004, respectively. A partial ecological life table constructed for egg stage indicated that 23-44% mortality occurs at this stage. Important factors responsible for egg mortality/loss were identified as T. chilonis, inviability, rain, wind and unexplained mortality.

The seasonal abundance patterns of the cotton aphid, Aphis gossypii Glover, in cotton fields at Gorgan in northern Iran were studied during two growing seasons of 2002 and 2003. The spatial distribution of different developmental stages and morphs of the aphid was described by fitting data to Poisson (random) and negative binomial (aggregated) distributions, and calculating the dispersion indices. A sequential sampling plan was also developed using the fixed-precision method of Green for estimating the density of the adult, nymph and total population. The first aphid colonies appeared on plants during late June and early July and peaked in early September when cotton plants were at the boll maturation and opening stages. Aphid populations, especially nymphs and apterous females, were aggregated during most of the growing season and negative binomial models fit data sets better than the Poisson series. The percentage fit for alate morphs showed a slight tendency to the Poisson distribution. With respect to sampling cost or required sample size, the developed fixed-precision sequential sampling plans showed an acceptable performance for estimating aphid density at the precision level of D=0.25. The optimum sample size was flexible and depended upon the aphid density and desired level of precision, and generally ranged from 10 to 513 and 62 to 3,206 at the precision levels of 0.25 and 0.10, respectively. The sequential sampling plans developed could be recommended to estimate the aphid density in integrated pest management programs.

The primary purpose of this research study was to determine the major factors affecting the implementation of national agricultural mechanization programs in Iran. The secondary purpose of this study was to assess the agricultural mechanization level practiced by farmers. This project consisted of two phases. In the first phase of the study, a Delphi technique was used to gather experts' points of view on variables affecting agricultural mechanization implementation programs in Iran. The second phase of the study was designed to assess the agricultural mechanization level practiced by farmers growing sunflower seeds. The Delphi technique investigation showed that the main constraints on farm mechanization were “small farm size” and “fragmentation of holdings”. The findings of the second phase of this research indicated that the mean agricultural mechanization level practiced on the sunflower producing farms was about 0.5 kW per ha of cultivated land. However the amount of energy input varied between 0.0149 to 3.4973 kW.Multivariate linear regression of the study indicated that 46.9% (R2= 0.469) of the variance in the level of agricultural mechanization practiced could be explained by variables such as income, total farming land, and land holdings under sunflower seed cultivation.

Nowadays, more attention is being paid to customers’ satisfaction as funding decisions are made. Extension organization, which plays an important role in educating farmers, must know how far the learners are satisfied with its educational program. Accordingly, this study was conducted in Yazd Province (Iran) with the main objective of investigating the pomegranate growers’ satisfaction with their extension - education courses. A survey method was adopted for the study and 150 people were selected as sample out of 478 learners participating in the courses from 2003-2004 throughout the province. A questionnaire was developed as the tool of study. The questionnaire was found to be valid and reliable (Cronbachs' alpha was 0.93). The results showed that the courses did not achieve many of their teaching objectives and were assessed as achieving their goals to a moderate extent. The contents of the courses were assessed as being comprehensive, applied, and new to a high, moderate, and low extent, respectively. The respondents are very satisfied with teachers’ characteristics and with the locality and facilities of courses, but were satisfied with teaching methods to a low extent. They generally had a positive and favorable attitude towards the pomegranate extension-education courses. According to the study there were significant relationships between learners’ satisfaction with courses and their annual income, pomegranate yield, pomegranate production, times of participation in courses, and attitude toward the courses. Stepwise regression analysis indicated that three variables, attitude toward the courses, pomegranate yield and pomegranate production totally accounted for 77.8 percent of variations in learners’ satisfaction with the pomegranate extension - education courses.

Two experiments were conducted to determine the effect of phytase supplementation on layer hens and broiler chickens performance and compare the use of phytase nutrient equivalency values in feed formulation with those fed conventional diet. In the first experiment, 640 commercial broiler chicks were used from 11 to 49 days of age. The experimental units were allocated at random to 4 dietary treatments×two sexes with 4 replicates per treatment. The first dietary treatment was formulated with no addition of phytase (C), the second diet contained 500 FTU kg-1 phytase over the top (C+P), and the third diet contained 500 FTU kg-1 phytase which was calculated as half of the nutrient equivalency values for phyatse (50E). The fourth dietary treatment contained 500 FTU kg-1 phyatse which was calculated as the total nutrient equivalency values for phytase (100E).In the second experiment 288 Hy-line W-36 hens were used from 60 to 72 weeks of age.The treatments consisted of a control diet (C) with no addition of phytase, a control diet supplemented with 300 FTU kg-1 phytase over the top (C+P), and a third diet containing 300 FTU kg-1 phytase which was calculated as the total nutrient equivalency values for phyatse (100E). No significant difference was observed among the four dietary treatments for broiler final body weight, feed conversion ratio (FCR) and carcass characteristics (P>0.05). The toe ash, and toe ash Ca and P percentage of broiler chickens increased with the addition of phytase (P<0.05). Hen day egg production for the C, C+P and 100E group were 75.25, 77.25 and 66.0%, respectively; as egg production declined, FCR increased significantly (P<0.05). There were no significant differences in egg specific gravity, egg shell thickness, shell breaking strength and egg and toe mineralization among the dietary treatments. The results of the present study indicated that using phytase nutrient equivalency in feed formulation has a beneficial effect on broiler performance, but did not have any beneficial effect on the performance of old layer hens. In conclusion, using the same AME and protein equivalency values of phytase for broiler and old layers is not a valid approach.

This research was performed to evaluate the potentials of Landsat MSS data for mapping land features in arid zones of southeastern Esfahan, Iran. Databases of the area were formed using all available relevant maps and reports which were supported by fieldwork.A supervised image classification approach was used and thirty-two training areas were applied. Separability of the spectral classes was examined using feature space plots of imagery data and self-classification of training areas. The accuracy of the classification was examined by using test and random pixels. The results show the potential of Landsat data for the discrimination of landforms and zones of the playas. Sand deposits (deflated sands and Barchans) expressed different spectral reflectance which could be due to mineralogy of these features. Soil classes differing in moisture content and salinity located on the soil line and limestone classes located along the soil line. The applied imagery data disable to discriminate Barchans from Bare soil I and Andesitic fans from Grey limestone. After image classification the spectral classes were merged to form landforms. The main landforms were mountains, piedmonts, sand dunes, valleys and playas. The results indicate that integration of field observation and supervised classification can compensate for the lack of detailed topographic maps in some areas.

The tadpole shrimp of genus Triops is a well-known living fossil whose fundamental morphology has been unchanged for 220 million years. We collected specimens of Triops cancriformis in temporary water bodies near the southern part of Urmia Lake (in the Fall of 2005). Some biological characteristics of this Triops were investigated. The feeding regime of T. cancriformis was found to be related to the fauna and flora of the temporary pools. Invertebrates and animal detritus were found to constitute major part of the feeding regime. The existence of Triops cysts and particles in the gut also showed certain degree of cannibalism. Morphological and histological investigations showed that the population of T. cancriformis was female and there was only one male among 400 samples collected.Observation of sperm among follicle ducts of a few samples indicated some degree of hermaphrodity, but the animal seemed to reproduce mainly through parthenogenesis.Fecundity, varying from 100 to 2500 cysts, was with a few exceptions related to the body size. The average cyst diameter was 400±85 mm.

Soybean mosaic virus (SMV) which belongs to the virus family Potyviridae, causes a disease in soybean that is present in soybean-growing areas of the world, and is widely distributed in northern Iran. Detection of SMV is very important for disease management. In the present study several serological and molecular (nucleic acid- based) methods of rapid virus detection were compared. Serological studies including DASELISA, DAC-ELISA, TPIA and DIBA were optimized and compared to identify the virus by using a polyclonal antibody. Among the serological methods, TPIA and DIBA are simple and TPIA is rapidly and easily applicable in the field. However, TPIA was found to be preferable. TPIA is time-saving, not requiring conventional sap extraction and also nitrocellulose membranes used for printing can be used in the field and stored for a long time or transported to other laboratory to be processed. RT-PCR and Immunocapture RT-PCR (IC-RT-PCR) were performed as molecular methods for detecting SMV using a pair of primers designed to amplify a fragment in the coding region of the SMV coat protein. To extract total RNA for RT-PCR, two methods including RNAWIZ and phenolchloroform were used. A part of the coat protein genome of SMV was converted to cDNA using a reverse transcription (RT) reaction. For IC-RT-PCR method, virus partial purification was carried out by solid-phase (0.2 ml microfuge tube) adsorbed polyclonal antibody, and then the RT reaction was carried out in the tube. In both methods cDNAs were amplified by PCR. Both methods amplified the expected fragment in virus-infected plants. Whereas RT-PCR requires total RNA extraction, ICRT- PCR does not have total RNA extraction problems. Our findings suggest that TPIA and IC- RT- PCR can be routinely used for SMV detection, with high efficiency.