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Agricultural Science and Technology - Volume:9 Issue: 4, Oct 2007

Journal of Agricultural Science and Technology
Volume:9 Issue: 4, Oct 2007

  • تاریخ انتشار: 1386/06/20
  • تعداد عناوین: 8
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  • A. Zomorodian, R. A. Tavakoli Page 259
    The equilibrium moisture content is an important parameter for several postharvesting operations for pistachio nuts, such as drying processes and storage. In this research the adsorption and desorption equilibrium moisture content were determined for two major varieties of Iranian pistachios at 11 to 85 percent relative humidities and a constant temperature of 50°C. A significant hysteresis effect between the adsorption and desorption processes was observed statistically. For predicting the adsorption and desorption EMC, the Halsey model was found the most proper equation for adsorption processes for two varieties (Ohadi and Kalehghochi), whereas the Oswin and Smith models were most appropriate for Ohadi and Kalehghochi for desorption processes, respectively, at constant a temperature of 50°C.
  • J. Ashkani, H. Pakniyat, Y. Emam, M. T. Asad, M. J. Bahrani Page 267
    Eight genotypes of spring safflower (Carthamus tinctorius L.) were evaluated for several physiological traits under stress and non-stress water regimes. Data were analyzed using principal factor analysis. The factor analysis technique extracted six factors under nonstress conditions. Six factors explained about 80% of the total variation, and only 40% of the variance was accounted for by the first two factors. Factors I and II were identified as water consumption, and water balance capacity, respectively. Similarly, seven factors were extracted under stress conditions, and 34% of the total variation was accounted for by the first two factors. Factors I and II were described as water conservation, and water holding capacity, respectively. Important physiological criteria were recognized by Factors I and II in two experiments. Ultimately, initial water content (at stem elongation and grain filling stages), canopy temperature (at stem elongation and flowering stages), and leaf water potential (at flowering stage) under non-stress conditions, and canopy temperature (at all stages), leaf area index (at stem elongation), and rate of water loss from excised leaf (at grain filling) were the best criteria for screening suitable genotypes under the afore mentioned conditions.
  • H. Farhangfar, H. Naeemipour Page 279
    A total of 136,250 monthly test day milk records collected from 13,625 Iranian Holstein heifers (three times a day milking) calved between 1991 and 2001 and distributed over 264 herds were used to study the effects of some environmental factors influencing lacta-tion curve parameters as well as production characteristics. Wilmink’s function (Yt = W0 + W1t + W2e-0.05t) was fitted to individual lactations. Least squares analysis of variance in-dicated that the herd, year and month of calving had a significant effect on all traits under consideration. Correlation analysis showed that the parameter W0 had a negative and significant (p<0.05) relationship with parameters W1 and W2 while it was positively sig-nificantly correlated with milk at peak time and 305-day milk yield. Simple linear regres-sion analysis of adjusted means of a 305-day milk yield, days to reach peak yield as well as peak milk yield in the first year of calving also revealed that there was a phenotypic in-crease of 137.152 Kg, 0.535 day and 0.434 Kg per year, respectively.
  • S. K. Alavipanah, M. Saradjian, Gh. R. Savaghebi, Ch. B. Komaki, E. Moghimi, M. Karimpour Page 287
    Due to the hard climatic conditions of the yardang region in the Lut Desert, not much information about land surface temperatures of this region, one of the extremely arid cli-matic zones of Iran, has been extracted. Therefore, in this study in order to obtain some information about important surface features of the Lut Desert (marl, grey sand, bright sand and salt affected land), field temperature measurements were taken and remotely sensed data processing were made. Temperature was measured eight times from 6 a.m. to 8 p.m. during a 15-day period in October 2000. In addition to field measurements, Land sat satellite TM thermal data dated on the 25th of June, 1989 and other sources of data and maps were used. Thermal remote sensing analysis was applied for mapping surface temperatures in the south-eastern part of the Lut Desert in Iran. In this research, the methodology comprised: 1) field temperature measurements, 2) the relationship between the temperature of different soil surfaces and land cover types, 3) diurnal variations in the surface temperature of land cover types, 4) primary image processing and fieldwork, 5) image processing and calibration,6) image classification and accuracy assessment, and 7) land surface temperature mapping. The results obtained have shown the differences be-tween the surface temperatures of the studied features. The significant differences be-tween surface temperatures were discussed. The results obtained have also shown the im-portance of thermal sensor selection from the viewpoint of satellite overpass time. The re-sults obtained from thermal data and field temperature measurements have shown the time of Landsat satellite overpass has to be considered for image interpretation. As a re-sult, the temperature lowers, respectively, in regions such as yardangs, desert pavement, salty lands, and wetlands; however, it increases in sandy regions.
  • M. R. Najafi, S. M. Hosseini, K. T. Lee Page 305
    In recent years, artificial neural networks (ANN) have been widely used for flood forecasting. In this study, an ANN model based on geomorphologic characteristics of a watershed is developed. The nodes in input layer are allocated to the surface, sub-surface flows, excess-rainfall and infiltrated rain. The number of nodes related to excess rainfall are predetermined according to time of concentration of the watershed. The dependability of the infiltrated rain, surface and subsurface flows to previous time steps are calculated, by assigning different number of nodes to each component. The results of the study show that the simulated hydrographs by the proposed ANN model has good agreement with the observed hydrographs
  • J. M. V. Samani, M. Heydari Page 317
    Rock has been advantageously employed in hydraulic structures such as rockfill dams, gabion weirs and drain works. One rockfill dam applications can be flood control in wa-tershed management. The objectives of building rockfill detention dams are flow storage for a specific period and lowering of the outflow hydrograph. As this type of dam consists of coarse particles, seepage flow will deviate from Darcy’s law and mostly be turbulent. Under the practical conditions of watershed management, it might be necessary to build successive rockfill dams, where a final outflow hydrograph with lower peak flows and longer duration is needed. Due to their reciprocal effects, the hydraulics of successive rockfill detention dams are complicated. This paper describes a routing flow model through successive rockfill dams considering the storage among them and their effects on each other. In the developed model, the velocity has been introduced to the 1-D continuity equation as an exponential relationship between Reynolds number (Re) and the Darcy-Weisbach friction factor (f). By introducing the inflow hydrograph and rockfill character-istics as input data to the model, the outflow hydrograph can be determined through the storage routing method. The results of the developed model show good agreement with the experimental data collected for this investigation. The results show that the degree of peak reduction of the routed hydrograph depends on the number of successive rockfill dams, the distance between them, the average size of the rockfill material, and the dam dimensions.
  • J. Zolala, M. Farsi, H. R. Gordan, M. Mahmoodnia Page 327

    Agrobacterium rhizogenes causes hairy root disease in plants. These hairy roots are ge-netically stable and grow rapidly. Transformed hairy roots of Hyoscyamus muticus in-duced by the bacterium can produce tropane alkaloids in trace amounts of intact plant tissues. In this research, in order to compare growth and biosynthetic stability of hairy roots with wild type ones, leaf and nodal segments of the plant were inoculated with the A. rhizogenes strains A4 and LBA9402. When hairy roots appeared, both the wild type and transformed roots were cultured in a liquid B5 medium. The amounts of tropane alka-loids in both the wild type and transformed roots were measured using HPLC. The growth rates of transformed roots were stable and their dry weights were up to four times higher than those of wild type roots. Alkaloid content was the same for both transformed roots and wild type ones. However, when hairy roots underwent an autonomous dediffer-entiation and produced callus, their hyoscyamine content decreased considerably, whereas not only did their scopolamine content, not decrease, but in some cases it in-creased dramatically. A callus producing hairy root clone, produced 2.72 mg/g scopola-mine which is a significantly high record for hairy roots of H. muticus.

  • H. Massumi A. Hosseini Pour Page 341
    A survey was carried out in five provinces of Iran (Kerman, Sistan and Baluchestan, Hormozgan, Khorasan and Yazd) for the presence of Alfalfa mosaic virus (AMV) sero-types in alfalfa during 2002 to 2003. The number of samples collected was 250, represent-ing the diversity and geographical distribution of AMV in these areas. Diagnosis was car-ried out using polyclonal (PAbs) and monoclonal (MAbs) antibodies. A total of 110 symp-tomatic leaf samples gave a positive reaction in ELISA with polyclonal antibodies. Twelve out of 20 MAbs reacted with all samples tested and were considered as non-differentiating MAbs. Only the MAbs-12, 13, 15, 21, 22 and 24 gave a clear differential reaction and were used for identifying AMV serotypes. Two MAbs (1 and 2) did not react with AMV posi-tive samples. Serological relatedness among AMV samples was studied by indicating the existence of six serotypes of AMV strains in the surveyed areas.