فهرست مطالب

Journal of Agricultural Science and Technology
Volume:12 Issue: 3, May 2010

  • تاریخ انتشار: 1389/04/06
  • تعداد عناوین: 12
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  • S. S. Hosseini, H. Shahbazi Page 255
    High and increasing beef marketing margin leads one to controversy about factors affecting it. This study using the monthly data for the 1998-2005 period to investigate the market power and to estimate how farm and marketing services supplies and retail demand determinants can affect beef marketing margin. The results show that farm, marketing services and retail level prices and thereby marketing margin move together in different ways that depend on whether the determinants that cause movement arise from a shift in retail demand, marketing services supply or farm supply. And also, positive impact of market power beef marketing margin is observed.
  • A. R. Bandani, M. Kazzazi, M. Allahyari Page 265
    A study of insect digestive enzymes makes sense given that the gut is the major interface between the insect and its environment. An understanding of gut and digestive enzyme function is essential when advanced methods of insect management such as application of enzyme inhibitors and transgenic plants are developed to control insect pests. The aim of the current research project was to study midgut anatomy, midgut pH and α-glucosidase activity in Sunn pest, Eurygaster integriceps Puton (Hemip: Scutelleridae). Sunn pest midgut is comprised of four distinct regions including first ventriculus (V1), second ventriculus (V2), third ventriculus (V3) and finally fourth ventriculus (V4). The study showed that the first three regions of the Sunn pest midgut are more acidic (pH= 5–5.2), the fourth region moderately acidic (pH= 6.2–6.4), and hindgut slightly acidic (pH= 6.5–6.8). Enzyme assay showed that α-glucosidase activity is present in midgut and salivary glands of adult E. intergriceps. The specific activity of midgut enzyme was 0.17 U mg protein-1 while the specific activity of the salivary glands enzyme was 0.033 U mg protein-1. Optimum temperature and pH values for α-glucosidase were determined to be 40-45°C and 5, respectively. Based on linear regression analysis of reciprocal p-nitrophenyl substrate (p-nitrophenyl α-D-glucopyranoside) concentration versus reciprocal α-glucosidase activity Km and Vmax were 17 and 0.9 mM p-nitrophenol min-1, respectively. The effect of different ion concentrations on α-glucosidase activity showed that Na+, K+, Mg2+, and Ca2+ ions exerted positive effects on the enzyme activity. Other compounds tested such as urea, SDS, Tween 80, Triton X-100 and EDTA had an inhibitory effect on enzyme activity.
  • A. Sedaratian, Y. Fathipour, A. A. Talebi, S. Farahani Page 275
    Population density and spatial distribution of Thrips tabaci Lindeman on seven soybean varieties (Williams, Tellar, Sahar, Dpx, L17, Sari and Zane) and one genotype (Ks3494) were studied in Tehran region, during 2007. The highest population density of the thrips per leaf was recorded on Dpx and on Ks3494 (0.810.05 and 0.800.05, respectively). The lowest population density was observed on L17 and Tellar (0.620.04 and 0.640.03, respectively). To estimate the spatial distribution pattern of this pest, data were analyzed through index of dispersion, Lloyd''s mean crowding, Morisita''s index as well as through regression models (Taylor and Iwao). The index of dispersion and Lloyd''s mean crowding indicated an aggregated pattern for the spatial distribution of this insect in all the varieties and the genotype of soybean. Spatial distribution of T. tabaci using Morisita''s index was aggregated in most of the sampling dates. In Taylor''s model, regression between log S2 and log m was not significant for Dpx varieties (P> 0.05), but the b values of Taylor''s power law on Zane, Sahar, Williams and Tellar varieties exceeded 1, indicating aggregated distribution. However, the other varieties had a b value equal to 1, indicating random distribution. Iwao''s patchiness regression indicated that the spatial distribution of T. tabaci on Sari, Zane, Williams and Tellar varieties as well as on Ks3494 genotype was aggregated, but on the rest of varieties the pattern was of a random one. It is concluded that soybean varieties affect the population density and spatial distribution of T. tabaci. Spatial distribution parameters of this species can be employed to outline a sampling program as well as to estimate the population density of T. tabaci.
  • O. A. Isah, O. J. Babayemi Page 289
    Nutritive value of Rumen Epithelial Scraping (REP) was assessed using in sacco and in vivo procedures. Concentrates were so formulated that 0% (A), 35% (B), 70% (C), and 100% (D) of Soybean Meal (SBM), were replaced (weight for weight) with REP. In a completely randomized design, 16 West African Dwarf (WAD) goats were randomly allocated to the experimental diets to assess feed intake and digestibility. In a second trial, the concentrates, SBM and the REP were degraded in the rumen of fistulated goats to determine Dry Matter (DM) and Crude Protein (CP) degradability. No significant difference (P< 0.05) was observed in DM and CP consumption of goats on the various dietary treatments. The variation observed for digestible DM and CP among diets were significant (P< 0.05). The highest value of digestibility coefficients of DM and CP were observed in diet B (77.72% and 79.2% respectively). There were significant differences observed (P< 0.05) in the DM and CP degradation characteristics of the different samples incubated in the rumen of goats. Rumen epithelial waste contained more soluble fractions (30.13% DM and 71.04% CP) than soybean meal (29.82% DM and 18.6% CP), and it was shown that increasing REP in the concentrate increases the soluble DM and CP (P< 0.05). The results indicated that REP is nutritive and can replace SBM at reasonable levels in goat production enterprise.
  • A. Moradi, J. Oladi, A. Fallah, P. Fatehi Page 299
    To evaluate the capability of IRS-P6 LISS-III data to be employed for monitoring the pollarding forest areas in Northern Zagros, some parts of pollarded forests located around Baneh city were selected as a case study area. The pollarding area was determined as the ground truth in a 3-year alternation period using a global positioning system (GPS). Radiometric and geometric corrections were applied to the image and then the data pre-processed, using 2 methods of Spectral Rationing and Principal Component Analysis (PCA). Likewise, multi-spectral bands were fused with IRS-1C PAN image, using the Intensity–Hue–Saturation Method (IHS). The obtained results were combined with the original bands. The separability of classes was studied using Bhuttacharrya Distance Criteria. The resulting data was classified using Maximum Likelihood Algorithm. Then the classified image was compared with ground truth on a pixel by pixel basis. In order to determine the classification accuracy, four parameters encompassing Overall Accuracy, Kappa Coefficient, Producer Accuracy, and User Accuracy were used. The results showed that most of the classes were completely separated from Northern Koor class. The highest overall accuracy was 70 % and a Kappa Coefficient of 60% obtained through a five-class classification of the bands combination PCA (4, 2, 3) -1, 4, 1. In this classification the resulted User accuracy and Producer accuracy were more than 50% for all classes expect for southern Khert. Results of the study revealed the high capability of the abovementioned image and methods to separate the pollarding areas and to prepare the map of the area.
  • M. R. Mobasheri, M. Chahardoli, M. Farajzadeh Page 309
    Ecological studies based on field data have shown that vegetation phenology follows a relatively well-defined temporal pattern. This pattern, that is reflecting the cumulative temperature from the date of the beginning of the growth, can be represented by the use of a suitable model. Due to the spatial, temporal, and ecological complexity of these processes a simple method to monitor phenological behavior of the vegetation canopies through remote sensing has proven elusive. Employing ASTER images from different seasons, might make it possible to produce an algorithm for sugarcane phenological date estimation and as well to monitor different stages of the plant growth from cultivation to harvest. For this, a parameter, namely Physiological Date is employed. Based on the field collected data and selected ASTER Images, 133 Regions Of Interest (ROI) having different Phenological Dates (PD) in units of Degree-Days (DDs) were supplied. One hundred of these samples were taken for modeling and another 33 for testing the models. Such indices as NDVI and SAVI along with PDs for the ROIs were calculated. The correlation between these indices and PDs was investigated. This ended up with the introduction of two models of PANDVI and PASAVI respectively based on the use of NDVI and SAVI indices for PD assessment. PANDVI model showed a better correlation with the field recorded data although either of the models can be well enough predictive.
  • S. Pirestani, M. A. Sahari, M. Barzegar Page 321
    Changes in the fatty acid content, during frozen storage at -24°C of Caspian kutum (Rutilus frisii kutum), golden grey mullet (Liza aurata), common carp (Caprinus carpio), pike perch (Sander lucioperca) and common kilka (Clupeonella cultiventris caspia), caught from south Caspian Sea were studied in the present work. Changes in saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), ecosapentaenoic acid plus docosahexaenoic acid/palmitic acid (EPA+DHA/C16), n3 PUFA/n6 PUFA (n3/n6) and polyunsaturated fatty acids/saturated fatty acids (PUFA/SFA) were investigated during a six month period. Results indicated that due to the decrease in unsaturated fatty acids particularly PUFAs (9.25-23.03%), and lower ratios of n3/n6 (2.02-6.06), EPA+DHA/C16 (polyene index; 0.21-0.65) and PUFA/SFA (0.18-0.64) the poststorage nutritional values of these species significantly decrease.
  • M. Javanmard Page 331
    The present study was carried out to investigate the occurrence of total mycobiota and Aspergillus species at different stages of fig production and processing in Iran. In the meantime, the potential of different culture media for isolation of fungal species from figs was also investigated. The mycobiota of 389 samples of dried fig were studied. Total fungal counts ranged from <2 to 6.74 log10 CFU g-1. In general, the predominant species were Aspergillus niger aggregate, Aspergillus flavus, Acremonium spp. and Mucor spp. in percentages of 90.9%, 63.7%, 54.6% and 36.4% infection, respectively. Other Aspergillus spp. and Mucor spp. Corresponded to 36.7% and 28.3% infection, respectively. The lowest contamination was observed in dried figs. The predominant fungi were Alternaria spp. and Penicillium spp. (9.1% infection). On average, Aspergillus spp. comprised 34.4% of the total fungal population. Aspergillus niger aggregate was detected in 99%, and A. terreus was present in 11.3% of total samples. The results revealed that poor hygienic conditions in fig harvesting, drying procedures, collecting sites, sorting and packaging plants caused higher mould contamination and risk of the A. flavus growth in dried fig production in Iran. As the result obtained from this study, using more than one culture media for isolation of A. flavus is recommended.
  • A. Afzal, S. F. Mousavi, M. Khadem Page 339
    Water is one of the most vital constituents in plants. In this research, for an estimation of leaf moisture content, the variation of capacitance was employed. The variations were measured via designed and manufactured capacitive sensors. The objective of the research was to estimate leaf moisture content by measuring its capacitance for five agronomic crops. Experiments for measuring leaf capacitance were performed on maize, sorghum, capsular bean, white bean and sunflower at two frequencies of: 100 kHz and 1 MHz. The results showed that in all cases the best fitted curve for variations of the capacitance in relation to leaf moisture percentage was in the form of an exponential function namely: y= aebx (where y is capacitance, x is leaf moisture content, a is the linear coefficient, and b is the exponential coefficient). Parameters a and b for different plants of each crop and each frequency were not significantly different at 1% probability level. However, these coefficients were significantly different among different crops. Coefficients of determination were higher at 100 kHz than at 1 MHz. It was also observed that the higher the leaf moisture the more the data points scattered around the best-fit line, although the scattering was more uniform at 1 MHz.
  • H. Dashti, M. R. Naghavi, A. Tajabadipour Page 347
    Inheritance of salinity tolerance was determined in a cross between two spring bread wheat cultivars, "Rovshan" (P1) a tolerant cultivar and "Falat" (P2) a susceptible one. The parents, F1, F2 and backcross generations were studied under salinity conditions (EC= 12 dS m-1) in a greenhouse. Eight characters namely: Heading Date (HD), Plant Height (PH), K+, Na+, K+/Na+ ratio, total Number of Tillers per plant (NT), Ratio of Fertile Tillers per plant (RFT) and total Chlorophyll Content (TC) were recorded to estimate means and variances pooled over replications, according to the weighted generation means analysis method. Generation means analysis of the data revealed that these characters show all types of gene actions (additive, dominance and epistasis) and suggest that complex epistatic effects are important in controlling salt tolerance characteristics. The highest broad sense heritability (0.87) was observed for K+/Na+, indicating the interference of a major gene in control of this trait. Regarding the existence of additive and non-additive effects in controlling traits in this cross, the recurrent selection followed by pedigree breeding may prove useful in improving salinity tolerance in wheat.
  • S. Mousanejad, A. Alizadeh, N. Safaie Page 357
    Grain yield loss in rice (Oryza sativa L.) caused by blast disease, Magnaporthe grisea (Hebert) Barr, is a major concern of rice growers worldwide. Blast is considered as the most injurious disease of rice in Iran, resulting in severe loss especially to susceptible rice cultivars. In order to assess yield loss caused by blast pathogen and develop an appropriate model, different disease onsets and levels were simulated in the experimental field in a split-plot experimental design. Independent variables including early diseased leaf area (X1), final diseased leaf area (X2), early neck blast index (N1), final neck blast index (N2), area under leaf blast disease progress curve (AUDPC1) and area under neck blast disease progress curve (AUDPC2) were taken as predictors and regressed to the loss in yield. Statistics as coefficient of correlation (r), coefficient of determination (R2), adjusted coefficient of determination (aR2), standard error (SE), F and Durbin-Watson were considered in evaluating the resulting models. The most appropriate model was the one which predicts rice yield loss based on final diseased leaf area and final neck blast index.
  • A. Keneni, P. C. Prabu, F. Assefa Page 365
    Density of Rhizobium population in faba bean (Vicia faba L.) fields of Wollo area (Asketema, Gashana, Kotem, Major and Sekota) northern Ethiopia was studied. The highest population of rhizobia was found at Major and the least at Sekota regions. The native rhizobial strains isolated from the northern parts of the country tolerated a higher salt concentration (5% NaCl) than the exotic rhizobial strains (Tall 1402 and Tall 1397). Both native and exotic strains failed to grow at pH 4 and 4.5 levels in the laboratory conditions. In the soil adjusted to pH 4-7, all the native rhizobial strains persisted while those of the exotic strain failed to survive at pHs below 5.5. The native strains were more versatile than the exotic ones in utilizing different carbohydrates as a sole carbon source and were found to be more resistant to many antibiotics (streptomycin, chloramphenicol, rimfampenicillin, oxytetracycline, penicillin and tetracycline) than the exotic strains which are found resistant to chloaramphenicol only. Percentage of nitrogen fixation is also higher for native rhizobial strains these isolates being found to be superior to the exotic strains in stimulating growth, dry matter yield, nodulation and nodule wet weight of faba bean in pouch culture.