Showing papers in "Journal of Agricultural Science and Technology in 2008"

Screening Potato Cultivars and Wild Species to Abiotic Stresses Using an Electrolyte Leakage Bioassay

Abstract: Ten Solanum tuberosum cultivars and accessions from 11 wild Solanum species were evaluated for their tolerance to salt (200 mM NaCl or 100 mM Na2SO4), drought (35% PEG), cold (-4oC) and heat (37oC). Evaluation was based on electrolyte leakage from detached leaves of in vitro plantlets. Testing involved a rinsing treatment with three changes of distilled water to remove electrolytes from leaf and petiole surfaces, an exposure period of 24 hours for salt and PEG stress and four hours for temperature stress and a rehydration period of 24 hours in distilled water followed by measurement of electrical conductivity into distilled water to determine the effects of stress. Significant differences were observed between Solanum genotypes for all types of stresses. Among the S. tuberosum cultivars, stress tolerance was great to NaCl and PEG in Alpha and Bintje; to Na2SO4 in Agria and to heat and cold in Norland. Among the wild species, tolerance to all stresses was great in S. demissum, to all stresses except heat in S. acaule and to heat and cold in S. commersonii. The correlations among types of stress tolerance were significant for all stresses except for heat and drought. The level of tolerance in some wild species was significantly greater compared with the cultivars tested. There appears to be a wide genetic base available to improve the stress tolerance of cultivated potato.

Evaluation of Wheat (Triticum aestivum L.) Genotypes under Pre- and Post-anthesis Drought Stress Conditions

Abstract: The responses of yield and yield components of 24 advanced bread wheat genotypes to pre- and post-anthesis drought stress conditions were studied at Ardabil Agricultural Research Station during the 1997-2000 cropping seasons. Results showed that genotypes produced signif icantly lower spikes No./m 2 , seeds No./spike and grain yield under prethan in post-anthesis drought stress conditions. However, an average of 1,000 kernel weight of genotypes under pre-anthesis was higher than under non-stress and postanthesis drought stress conditions. Selection based on TOL and SSI identified the drought tolerant genotypes with low grain yield. However, selection based on MP, G MP and STI identif ied drought tolerant genotypes with a high yield. G enotypes No. 13, 14 and 21 were determined as desirable genotypes based on their high grain yield under non-stress, preanthesis and post-anthesis drought stress conditions. The interaction eff ect of genotype x year was signif icant f or membrane stability and membrane damage, however, the interaction eff ect of genotypes × stages of measurement (booting and heading) were not signif icant. On the basis of these results, genotypes No. 13, 14 and 21 with low membrane damage were also identified as drought tolerant genotypes. It can be concluded that the laboratory test can be an usef ul tool in a breeding program f or improving drought tolerance in wheat.

Mapping qtls for heat tolerance in wheat.

Abstract: Heat stress is a major environmental stress limiting wheat productivity in most cereal growing areas of the world. In order to map and characterize quantitative trait loci controlling heat tolerance, 144 recombinant inbred lines deriving from the cross of Kauz and MTRWA116 were assessed in a greenhouse and growth chamber at 35˚C. One hundred and sixty six SSR and 3 AFLP markers were used to construct a linkage map containing 18 linkage groups and covering 16 chromosomes of wheat. Using the composite interval mapping method, three QTLs were detected for heat tolerance and measured by the Fischer susceptibility index, on chromosomes 1B, 5B and 7B. The alleles of both parents contributed to heat tolerance. A large amount of explained phenotypic variances and small confidence intervals indicate that the linkage information between markers and QTLs could easily be used in breeding for heat tolerance.

Effects of nitrogen fertilization and plant growth regulators (PGRs) on yield of wheat (Triticum aestivum L.) cv. Shiraz.

Abstract: Plant growth regulators (PGRs) are widely used for lodging control in winter wheat (Triticum aestivum L.) grown at high N rates. Although the introduction of semi-dwarf wheat cultivars had largely solved the problem of lodging, evidence was already accumulating that the timely application of a growth retardant such as chlormequat (CCC) or ethephon could increase the grain yield of wheat, by the alteration of dry matter partitioning independently of any control of lodging. A field experiment was conducted the during 2004-5 growing season at the experimental farm of the College of Agriculture, Shiraz University (Shiraz, Iran,) located at Badjgah. The design of the experiment was a randomized complete block with treatments arranged as split plot with four replicates. Nitrogen levels (0, 100 and 200 kg ha -1 ) were the main plots. The N was applied as Urea (46% N), half at the time of stem elongation and the other half at onset of flowering. The PGR treatments included CCC at 2.20 kg ha -1 applied at Zadoks growth stage (ZGS) 25, ethephon at 0.28 kg ha -1 at Zadoks growth stage (ZGS) 39, and controls (without any PGR) were assigned to sub-plots. The results showed that both PGR treatments reduced the plant height and this reduction played an important role in the increase of the grain yield in wheat, via the alteration of dry matter partitioning into the spikes. However, CCC at 2.20 kg ha -1 applied at ZGS 25 increased the grain yield (8.9 t/ha) significantly, compared to the ethephon (8.2 t ha -1 ) and control (7.2 t ha -1 ) treatments; the highest grain (8.9 t ha -1 ) yield was obtained at 200 kg ha -1 N and 2.20 kg ha -1 CCC application. The beneficial interactive effects of PGRs and nitrogen rates on winter wheat yield are worthy of further exploration.

Investigation of Annual Rainfall Trends in Iran

Abstract: This paper presents an analysis of annual precipitation trends in Iran. Mean annual rainfalls were collected from 30 synoptic stations with a reasonable geographic distribution and with data equal to or less than 50 years. Trend analysis was investigated using a "regression line slope" method (annual rainfall as a dependent variable and year as an independent variable). The results showed that for the entire period, and at a 95% level of significance, seven stations showed a negative trend, while a positive trend was found at six stations. The same data over the period of last 40 years demonstrated that four and 8 stations had negative and positive trends, respectively. Decreasing the record length, up to the last 30 years, resulted in fewer stations with any significant trend. The results identified that, in any case, the trend did not depend on the mean annual rainfall but rather record length could have some effects on it.

Diversity of clay minerals in the vertisols of three different climatic regions in western iran

Abstract: Considerable information exists in the literature showing that expansive layer silicates are not the only clay minerals present in vertisols. However, the presence of a very high clay content dominated by fine clay, regardless of the clay type, together with the wetting and drying cycle in the soil can also produce a high shrink-swell potential. We studied some vertisols with diverse parent materials and climates from western Iran to investigate the role of parent material and climate on formation of these soils. The vertisols of Fars Province (Southwest Iran) have formed on calcareous sediments with ustic-hyperthermic soil moisture and temperature regimes and a mineralogical composition dominated by a palygorskite-chlorite suite. The vertisols of Lorestan Province (Midwest Iran) are also formed from calcareous sediments under the xeric moisture and thermic temperature regime, and contain vermiculite as the dominant clay mineral. In Kermanshah Province, vertisols have formed on limestone or in calcareous sediments. They have xeric-thermic soil moisture and temperature regimes. In Ardebil Province, vertisols are formed on volcanic sediments, and they have xeric-mesic soil moisture and temperature regimes. All vertisols, except those from Fars Province, are classical ones and include montmorillonite in the clay fraction. Our study shows that the interparticle pore size that is controlled by the size of primary particles, regardless of its nature, contributes to the shrink-swell potential in the soils we studied in Iran.

Factors Affecting the Academic Success of Agricultural Students at University of Tehran, Iran

Abstract: Discovering the effective factors in agricultural students’ academic success was the aim of this study. The statistical population consisted of all 194 junior agriculture students at the University of Tehran. The study is of a correlation type with the information being gathered through questionnaires as well as through a study of students’ academic files. There was a positive significant correlation observed (P= 0.01) between academic success, on the one hand, and high school grade point average (GPA), study hours, planning for study, motivation, and emotional atmosphere of educational environment, on the other hand. The level of confidence between academic success, on one hand, and the family’s attitude towards studies and years of experience in teaching, on the other, being also significant (p= 0.05). Female students were found to be more successful than males. There was no significant difference observed between the academic success of students in residences and those who lived with their parents. Students with agronomy majors were shown to have a higher academic success as compared to students majoring in other eleven majors within the agricultural faculty. The results of regression analysis also demonstrated that 63.5 percent of the variations in the dependent variable academic success were expressed through high school grade point average (GPA), motivation, method of learning, father’s level of education, and the emotional atmosphere of the educational environment.

Production of Bioethanol and Sunflower Methyl Ester and Investigation of Fuel Blend Properties

Abstract: Biofuels are the main substitute to fossil fuels. These fuels are less polluting in comparison to fossil fuels and can be produced from agricultural material residues for use in diesel engines. In this research work bioethanol was produced from potato waste. It was dehydrated in a vapor phase using 3A zeolite and was used in combination with sunflower methyl ester oil and diesel fuel blending which was evaluated thereafter. The sunflower methyl ester was also produced using a transesterification method. Considering the laboratory conditions and fuel stability limits to be used, the suitable blending proportion of bioethanol and diesel fuel was determined to be 12 to 88 and then, for maintaining fuel stability at temperatures lower than 15 o C, the sunflower methyl ester was added to the mixture. The pour point of the fuel and different fuel blends, the viscosity, cetane number, flash point, amount of fuel ash, sulfur content and copper corrosion were determined in the laboratory. Experiments show that ethanol plays an important role on the flash point of the blends. With the addition of 3% bioethanol to diesel and sunflower methyl ester, the flash point was reduced to 16 o C. The viscosity of the blends was reduced with the increase in the amount of ethanol. The sulfur content of bioethanol and sunflower methyl ester is very low compared with that of diesel fuel. The sulfur content of diesel is 500 ppm whereas that for ethanol and sunflower methyl ester is 0 and 15 ppm, respectively. The lower amount of sulfur content facilitates the use of fuel blends in diesel engines. For the ethanol and sunflower methyl ester combination, this amount is less than 20 ppm.

Prevalent pathotypes of puccinia striiformis f.sp. tritici in iran

Abstract: The stripe (Yellow) rust in wheat is one of the most important plant diseases in Iran. Since 1993 several epidemics have occurred in Iran causing the breakdown of widely utilized sources of resistance in wheat cultivars. Twenty-seven pathotypes were identif ied during 2003 and 2004 in greenhouse tests. Pathotypes 6E6A+, 6E22A+, 6E130A+, 6E134A+, 6E142A+, 6E158A+, 134E130A+ and 134E142A+ were more common during the course of this study. Virulence on plant/s with gene/s Yr2, Yr6, Yr7, Yr8, Yr9, Yr24, Yr25, YrSD, YrSP, Yr3N, Yr2+, Yr6+, Yr9+, Yr7+, Yr32+ and YrA was detected under greenhouse conditions. The majority of isolates with a high frequency (more than 88%) showed virulence on plant/s with Yr2, Yr6, Yr7, Yr9, YrA and Yr24 genes. No virulence was detected on plant/s with Yr1, Yr3V, Yr4, Yr5, Yr10 and YrSU genes. In a greenhouse test, frequency of virulence to wheat genotypes with the Yr32+, YrSP and YrSD gene was less than 7%; frequency of virulence to all other wheat genotypes was between 19 and 100%. During three years of f ield study, virulence on wheat genotypes Heines Kolben (with genes Yr2 and Yr6), Kalyansona (Yr2), Lee (Yr7), Avocet R (YrA), Federation*4/Kavkaz (Yr9) and TP1295 (Yr25) was common. No virulence was observed on plants with Yr1, Yr3V, Yr3N, Yr4, Yr5, Yr8, Yr10, Yr18, Yr24, Yr32+, YrSP, YrSD and YrSU genes in the trap nurseries. The coefficient of infection (C. I.) of the adult plant resistance gene, Yr18, was between 16-64 with moderate susceptibility and is going to be used in the breeding program in combination with other resistant sources.

Interactive effects of nacl levels and zinc sources and levels on the growth and mineral composition of rice

Abstract: The effects of sodium chloride and Zn rates and sources on the growth and chemical composition of lowland rice ( Oryza sativa L.) were studied using calcareous soil in a greenhouse experiment. The treatments comprised 5 levels of NaCl (0, 12.5, 25, 37.5 and 50 mmol kg -1 soil), three Zn rates (0, 5 and 10 mg kg -1 soil) and two Zn sources (ZnSO 4, 2H 2O and ZnEDTA). Applied salinity decreased shoot dry weight, leaf area and chlorophyll concentration, whereas Zn supply significantly increased these growth parameters. However, the enhancing effect of soil Zn fertilization was more pronounced at lower NaCl levels than under higher salt stress, irrespective of Zn sources. Concentrations of Zn, P and K were significantly decreased and those of Na and Cl increased in NaCl-treated plants. Zn application markedly increased Zn concentration and decreased Na and Cl and P accumulation in shoots. Moreover, there was a significant difference between the two Zn sources to affect rice growth. Free proline increased but reducing sugars decreased with an increase in the levels of substrate NaCl. However, Zn-untreated rice contained higher proline and reducing sugars than Zn-treated plants. Furthermore, an increase in proline was greater in the presence than in the absence of Zn and with ZnSO 4 than with ZnEDTA. It is concluded that a decrease in soil osmotic potential, nutrient imbalance and excessive plant accumulation of Na and Cl in NaCl-treated plants caused growth suppression, whilst Zn supply decreased the suppressing effects of excess salt on rice growth. Therefore, it is recommended that for growing rice in saline soils that are low in available Zn, Zn should be supplied in a adequate quantities.

Natural Enemies of Cypress Tree Mealybug, Planococcus vovae (Nasonov) (Hem., Pseudococcidae), and their Parasitoids in Tehran, Iran

Abstract: The cypress tree mealybug, Planococcus vovae (Nasonov) (Hem., Pseudococcidae) is one of the most important pests of cypress trees, especially Cupressus semprevirens fastigiata L. in Iran. A survey was carried out to determine the natural enemies of cypress tree mealybug in Tehran Province, during 2004-2005. As a result of this study, 17 species of predators, parasitoids and hyperparasitoids belonging to 10 families and 15 genera were collected and identified. Among the natural enemies associated with P. vovae three species, Coccidoxenoides perminutus Girault (Hym., Encyrtidae), Aprostocetus ceroplastae (Girault) (Hym., Eulophidae) and Pachyneuron bonum Xu and Li (Hym., Pteromalidae) were recorded here for the first time from Iran. The diagnostic morphological characteristics of the newly recorded species are given here and illustrated. The host range and economic importance of its natural enemies are reviewed and discussed.

Evaluation of Barley-Vetch Intercrop at Different Nitrogen Rates

Abstract: To evaluate the yield and quality of barley (Hordeum vulgare)–vetch (Vicia desycarpa) intercropping, a series of experiments were conducted at the Experimental Field of the College of Agriculture, University of Tehran, in Karaj (Iran) from 2003 to 2005. The experiments were arranged in a randomized complete block with a split plot design and four replications. Three levels (0, 45 and 90 Kg N ha -1 ) of nitrogen fertilizer and three cropping systems (sole barley, sole vetch and barley-vetch intercropping) were allocated to the main and sub plots, respectively. The barley-vetch intercropping treatment had a replacement arrangement (50: 50) with single alternate rows. Land equivalent ratio (LER), was used to compare sole cropping with intercropping systems. Results showed the supremacy of intercropping of barley and vetch over single crops. Generally, increasing nitrogen fertilizer caused a decreasing trend in the biological efficiency of intercropping. The highest LER for grain was obtained in control (N fertilizer free) plots (LER= 1.145). Nitrogen fertilizer increased the forage yield, grain yield, crude protein content, and crude protein yield of barley and vetch in sole and intercrops. Nitrogen application increased water use efficiency. In this study, barley was the dominant crop. The intercropping vetch and barley had the highest productivity and crude protein yield.

Comparison of Antioxidative Effect of Tea and Sesame Seed Oils Extracted by Different Methods

Abstract: Tea and sesame seed oils extracted by different methods (including supercritical fluid extraction (SFE), at a pressure of 350 atm, a temperature of 60 o C, a static extraction time of 20 minutes, a dynamic extraction time of 30 minutes and 150 g kg -1 of ethanol as a modifier). Solvent (SE) and ultrasound-assisted solvent extraction (UE)), as natural antioxidants, were evaluated during 15 days storage by monitoring their effects on refined sunflower oil at 60 o C. The peroxide value (PV) and the thiobarbituric acid (TBA) value were used to assess the antioxidant activity of these extracted oils. The highest extraction yields were from SE and SFE, while UE gave a lower yield. Considering oil extraction yield and antioxidant activity, SE and SFE were the preferred methods. The results showed that tea seed oil had strong antioxidant activity, which was almost equal to sesame oil. Therefore, tea seed oil can be used in the same way as sesame seed oil in fat, oil and other food products as a natural antioxidant to suppress lipid oxidation.

Growth, Mineral Nutrition and Selected Soil Properties of Lowland Rice, as Affected by Soil Application of Organic Wastes and Phosphorus

Abstract: Lack of adequate organic matter (OM) in the agricultural soils of Iran is responsible for the poor physical condition of these soils. Thus, increasing soil OM is very important. On the other hand, the eutrophication of surface water caused by continuous use of phosphorus (P) fertilizer has created an interest in the combined use of organic wastes and P fertilizer. Hence, the present study was undertaken to study the effects of several levels of municipal waste compost (MWC), poultry manure (PM) and P on the growth and elemental composition of lowland rice ( Oryza sativa L.) and on selected soil chemical characteristics. There was a consistent increase in the shoot dry weight as the levels of MWC, PM or P increased. However, rice shoot growth was stimulated more by MWC than by PM and the enhancing effect of P on shoot growth was greater in MWC-treated plants than that of PM. Shoot P concentration increased with increasing levels of MWC, PM and P, whereas nitrogen (N) concentration was only affected significantly by the two organic wastes. Iron (Fe) and zinc (Zn) concentration was suppressed by P supply in PM-amended soil and was not affected by MWC treatment. Rice seedlings treated with either of the biosolids accumulated more Fe, Zn, chloride (Cl) and sodium (Na) but less manganese (Mn) than the control plants. Furthermore, rice plants grown on MWC-amended soil contained higher Fe and Mn and lower Cl and Na than those grown on PM-treated soil. In the present study, lead (Pb) and cadmium (Cd) concentrations did not follow a definite pattern with either of the organic wastes, whereas they increased with P application. Post-harvest soil sample analysis indicated that soil addition of MWC and PM increased concentrations of soluble salt, OM, N, NaHCO 3soluble P and DTPA-extractable Fe, Mn, Cu, and Pb.

The Efficiency of Landsat TM and ETM+ Thermal Data for Extracting Soil Information in Arid Regions

Abstract: A knowledge of soil surf ace conditions, especially desert crust, salt crust and desert varnish is usef ul f or improving classif ication of remotely sensed data. Desert crust can generate high levels of ref lectance, similar to those areas with high salt concentration and non-saline soil. Theref ore, soil surf ace crusts might bias thematic remote sensing of soils. In this study, we evaluated the ef f iciency of the Thematic Mapper (TM) and Enhanced Thematic Mapper plus (ETM + ) ref lective and thermal bands in detecting crusted surfaces and soil salinity conditions. The study areas were Ardakan, Damghan, Lut Desert, Q om, and Abarkooh which are located in arid regions of Iran. To assess the Landsat TM thermal data f or detecting land cover types, the f ollowing steps were taken: 1) determination of correlation coef f icients between TM wavebands, 2) assessment of the relationship between TM thermal and TM ref lective bands on land cover types, 3) assessment of the relationship between soil salinity and TM Digital Numbers (DN), 4) two dimensional Feature Space (FS) analysis of the training samples, 5) field sampling, 6) image classification and accuracy assessment, and 7) comparison of surf ace ref lectance of dif f erent soil surf ace types. The results show that the trend of correlation coef f icients of TM6 with ref lective bands is completely dif f erent f rom the correlation between ref lective bands. The behaviour of the thermal band on gypsif erous soils is completely dif f erent f rom that on saline soils. Moreover, with an increasing correlation between soil salinity and ref lective bands, the correlation between soil salinity and the thermal band decreases. In image classification, the thermal band improved the separability of the crusted and gravely classes. Theref ore the TM/ETM + regions of the electro-magnetic spectrum have complementary capabilities f or spectral separability of gravely and crusted surf aces. In general, selection of the TM/ETM + thermal band combination is an important step f or classif ying the remote sensing data and f or securing class separability of gravely and crusted surf aces in arid regions. We also concluded that TM/ETM + thermal bands may contain inf ormation complementary to the TM/ETM + ref lective bands and theref ore this combination of the TM/ETM + thermal and ref lective bands provide a viable method f or soil salinity studies

Determining Optimum Conditions for Sugarcane Juice Refinement by Pilot Plant Dead-end Ceramic Micro-filtration

Abstract: The conditions for the refinement of clarified sugarcane juice, including temperature (50 o , 60 o and 70 o C) and pressure (0, 0.5, 1 and 1.5 bars) by micro-filtration membrane technology were investigated. The raw sugarcane juice was initially pre-filtrated with lime and then the juice obtained (clarified juice) processed using a ceramic micro-filter membrane (0.2 micrometer). The characteristics investigated included brix, polarity (sucrose percent), turbidity, color and purity. The results showed that the effects of different process conditions with micro-filtration on reduction of turbidity and color were significant at probably <0.01 and probably <0.05, respectively. For other characteristics, no significant difference was observed. Finally, a temperature of 70 o C and transmembrane pressure of 1.5 bar were determined as the optimum conditions for ceramic micro-filtration. Membrane processing at 70 o C and 1.5 bars reduced the turbidity, viscosity and color of clarified juice 56.25%, 16.67% and 6.49%, respectively, and increased 0.87 units of purity.

Determination of Ammonia-N in Silage by Flow Injection Analysis

Abstract: Ammonia-N in silage was determined by flow injection analysis.The detection limit was 1.99 μg/L,correlation efficient r was more than 0.999,the RSD was 1.03% and the reclaim ratio was 96%～108%.The method has the characteristics of simplicity,sensitivity and good correlation.It is suitable to be used for determination of ammonia-N in silage with large quantity of samples.

Improvement of Functional Properties of Glutens Extracted from Two Iranian Wheat Varieties (Sardari and Mahdavi) Employing Chemical and Enzymatic Modifications

Abstract: Proteins are not only considered as a nutritional source but also are responsible for a number of functional properties such as solubility, emulsification, foaming capacity and gel formation in food products. However, insolubility of the proteins (as can be seen in gluten) and therefore their insufficient functional properties have created some limitations for their incorporation in formulated foods. Studies have indicated that chemical and/or enzymatic modifications are potential ways to improve proteins functionality. In this study gluten was extracted from two wheat varieties, Sardary and Mahdavi, and then modified by deamidation, acylation (succuinylation and acetylation) as well as enzymatic hydrolysis. Functional properties such as solubility measured as nitrogen solubility (NSI), emulsifying capacity (EC), foaming capacity (FC) and stability (FS) as well as the electrophoresis patterns of native glutens were studied and compared with those of chemicallyand/or enzymatically-treated samples. Most modifications significantly increased NSI from 20 to more than 70% and EC up to 35%. A great increase was also evidenced in foaming capacity that increased from 80 ml of foam volume in native samples to about 180 ml of foam in all the treated samples; however, only deamidated samples had stable foam over the time. Electrophoresis patterns indicated that, among chemical modifications, deamidation caused limited hydrolysis of gluten polypeptides while enzymatic hydrolysis led to a pronounced reduction in the molecular weight of wheat gluten polypeptides (less than 15 KD) of both varieties.

Determination of the degree, level and capacity indices for agricultural mechanization in Sarab region.

Abstract: The purpose of this study was to determ the degree, level and capacity indices of agricultural mechanization in Sarab Region (N: 37o45', E: 47o30') in Eastern Azarbayjan Province, comprising about 65,164 hectares of farming land. The number of tractors, types of machines, and degree, level, and capacity of mechanization were calculated as the method of study. Data showed that the average level of mechanization was equal to 0.83 (hp per ha); partial energy expenditure per hectare (mechanization capacity) by energy producing sources (human, animal and machine), was 1.24%, 2.23%, and 96.35 % respectively. The results show the importance of the role of the machine in production. Although the level of mechanization in this region was higher than the national mechanization level, the degree of mechanization was very low in most of the farming operations. It was estimated that to reach the mechanization level of 1.5 hp ha -1 , 775 tractors are required. In this study some overall guidelines for improving mechanization and increasing farm production are also presented.

Isolation, identification and differentiation of local B. thuringiensis strains.

Abstract: In this research, 514 soil samples and dead larvae were collected from Khorassan, Lorestan, Tehran, Ghazvin, East Azarbaijan, West Azarbaijan, Mazandaran and Hamedan Provinces. B. thuringiensis was isolated from the samples using a heat-acetate method and the isolates were identified and classified using biochemical tests. The frequency of B. thuringiensis in soils with different plant communities was studied. According to results, 127 isolates were collected from the samples collected. Most isolates produced atypical and heterogenic and some bipyramidal crystals. Nearly all the isolates were able to hydrolyze starch and gelatin and ferment glucose and fructose, but could not produce indole and H 2S or ferment galactose and lactose. The isolates were divided into 8 biochemical types, among which B. thuringiensis subsp. kurstaki was the most frequent type. Total Bt frequency, corresponding to the whole sampling areas, was calculated as being 3.1%; the highest frequency was recorded for Khorassan Province (5.1%) and the lowest for Lorestan Province (0%). No realtionship was found between B. thuringiensis frequency and vegetation status of the soils examined.

Effects of Nitrogen Levels, Nitrogen Sources and Zinc Rates on the Growth and Mineral Composition of Lowland Rice

Abstract: Nitrogen use efficiency (NUE) is usually lower in paddy rice ( Oryza sativa L.) than in upland crops. For this reason, any attempt to improve NUE through the use of different nitrogen (N) carriers, different rice cultivars, properly timed N application, the use of nitrification and urease inhibitorsis of prime interest. Moreover, zinc (Zn) next to N seems to be the most important soil factor affecting rice growth. Although the response of rice N and Zn fertilization has been reported elsewhere, the authors are not aware of any such information for the calcareous paddy rice soils of Iran. Therefore, the present experiment was conducted to study the effects of varying sources and levels of N and Zn rate on the growth and N and Zn concentrations and uptake by rice. Treatments consisted of five N levels (0, 50, 100, 200, and 400 mg N kg -1 soil), four N sources [urea (U), sulfur–coated urea (SCU), ammonium sulfate (AS), and ammonium chloride (AC)] and three Zn rates (0, 5, and 10 mg Zn kg -1 soil as zinc sulfate). The experiment was factorially arranged in a completely randomized design with three replicates. The results showed that the highest top dry weight was obtained with SCU, and followed by AS, AC and U. Application of N up to 200 mg kg -1 as U, AS, and AC increased rice growth significantly. However, there was a consistent significant increase in shoot growth with the addition of SCU. In the present study, Zn fertilization had no significant effect on rice growth. The uptake and concentration of N and Zn were increased by application of N and Zn. However, the highest Zn concentration and uptake were obtained with AC and SCU, respectively. Nitrogen and Zn addition generally increased leaf area and the maximum leaf area was obtained with SCU. Nitrogen yield efficiency (NYE) was reduced with increasing N rates (as U, AS, and AC) and increased up to 200 mg N kg -1 as SCU. Apparent N recovery (ANR) increased with increasing N up to 200 mg kg -1 as U, AS, and AC and declined thereafter. However, there was an increase in ANR with an increasing N level as SCU. On the other hand, N physiological efficiency (NPE) decreased with increasing N rates regardless of N sources. From the results reported here, it appears that 200 mg N kg -1 is the most appropriate N level and SCU appears to be the most efficient N source for lowland rice.

Comparison of Complete and Sulfur Coated Urea Fertilizers with Pre-plant Urea in Increasing Grain Yield and Nitrogen Use Efficiency in Wheat

Abstract: In order to increase grain yield, nitrogen use efficiency (NUE) and nitrogen apparent recovery fraction (NARF) in wheat (Triticum aestivum L.), this experiment was carried out with 5 or 6 treatments and 3 or 4 replications in 14 locations at 22 different sites in Iran during the 2004-05 growing season. The experiment was designed as a completely randomized block. The effect of N sources and timing on the grain yield, protein content, NUE and NARF of the current best adapted cultivars of different regions were evaluated. The treatments included T1= the control; T2= 150 kg ha -1 of N as urea in 3-split applications; T3= 150 kg ha -1 of N as urea in 2-split applications; T4= 150 kg ha -1 N as SCU as the base fertilizer; T5= 1 /3 N as SCU as the base fertilizer +2-split urea applications and T6= 1 /3 N as complete fertilizer as the base fertilizer +2-split urea applications. Protein content, NUE and NARF were calculated by measuring grain yield, N% and N-uptake. While the average grain yield and protein% for the control plots were 2,840 kg ha -1 and 10.03%; the yield and protein for T2, T3 and T4 were 4,160 kg ha -1 and 11.66%; 4,278 kg ha -1 and 11.78%; and 3,921 kg ha -1 and 11.60%, respectively. Grain yield and protein content for T5 were 4,330 kg kg -1 and 11.89%. Yield of 4,674 kg ha -1 and protein content of 12.01% were obtained by substituting complete fertilizer with 1/3 urea (T6). The grain yield for T6 was significantly different from T2 for various reasons, including higher levels of available P, K, S, Zn, lower N-leaching and appropriate N-timing. NUE for T2, T3, T4, T5, and T6 was measured to be 8.8, 9.6, 7.3, 9.9, and 12.2 kg kg -1 , respectively, and NARF were calculated to be 23.2, 25.3, 19.4, 26.3 and 31.6%, respectively. While the superiority of complete and SCU fertilizers over pre-plant urea has been proven, especially in the light-textured soils, it is highly recommended that the experiment be further tested and evaluated, since this practice has been increased the grain yield up to 12%, NUE up to 39 kg kg -1 and NARF up to 36% in comparison with the best wheat growers’ N-fertilization practice.

Rheological and Sensory Evaluation of Yoghurts Containing Probiotic Cultures

Abstract: In this study, the possibility of including probiotic starter cultures for making yoghurt was investigated. Set yoghurts were made using three bio-cultures, all containing Bifidobacterium spp.. The effects of these starter cultures and total solids (i.e. addition of 0, 1 and 2% skim milk powder) on the rheological and sensory characteristics of the bioyoghurts were compared with a standard starter culture (CH1) on the day of production (Day 0) and after 7 and 14 days storage at 4 o C. The rheological properties were evaluated using a Universal Texture Analyser and sensory analyses were carried out using a five point hedonic scale. The results of texture studies showed that the type of starter culture had a significant effect on the rheological parameters including hardness, springiness, cohesiveness, adhesiveness, chewiness and gumminess (P<0.05). It was also concluded that addition of skim milk powder (at the levels tested) did not change the hardness and springiness significantly, while adhesiveness, cohesiveness, gumminess and chewiness were statistically different at P<0.05. The results of sensory analysis indicated that the overall acceptance of bio-yoghurts was higher compared with the control. The higher sensory and textural scores of bio-yoghurts as well as their potential therapeutic effects may well be encouraging for the Iranian dairy industry.

Resistance of Potatoes to Airflow

Abstract: Knowledge of airflow resistance is an important consideration in designing an appropriate ventilation system and for proper fan selection. An airflow resistance device was designed and fabricated to measure the airflow resistance of potatoes. The device the composed of an air compressor, a rotameter, a cylindrical bin to contain the potatoes and an inclined u-tube manometer. Airflow resistance of potatoes was measured as a relationship between the airflow rate and pressure drop per unit depth (Pa/m) at 12 airflow rates of 0.085 to 0.55 m 3 s -1 m -2 . Two airflow resistance models, namely, Shedd’s and Hukill and Ives’, were fitted to measured data by using PROC NLIN of SAS. The effect of potato size below 120 g (small), at or above 120 g (large) and unsorted (mixed size), and bed depths of 25, 50, 75 and 100 cm of potatoes on resistance to airflow was determined. Results showed that the airflow resistance of small size potatoes for a 100 cm bed depth was 1.6 times higher than that for large size potatoes, and as the bed depth of potatoes was increased, the airflow resistance was increased.

Investigation of Leadership Style Correlates Affecting Jihad-e-Keshavarzi Staffs Job Satisfaction in Yazd

Abstract: Staff job satisfaction is very important for assessments leading to organizational development. Job satisfaction is a general attitude of workers towards with their job and it depends on the sum of all factors in organizational relations. The correlates of organizational leadership style such as process of leadership, motivating factors, communication, process of decision making, and characteristics of the control process all directly affect job satisfaction. This study was conducted to determine the correlates of leadership style that affect the job satisfaction of Jihad-e-Keshavarzi staff working in Yazd Province. The population consisted of all the Jihad-e-Keshavarzi staff in Yazd (N=298). The sample was obtained through simple random sampling technique (n=100) and 91 questionnaires were completed and returned. Data was analyzed by SPSS. There was a positive and significant relationship between job satisfaction and the leadership style correlates of the respondents (process of leadership, motivating factors, communication, process of decision making, and characteristics of the control process). The best predicators of job satisfaction were found to be the leadership and communication processes.

Evaluation of Relationship between Moisture Loss in Grapes and Chlorophyll Fluorescence Measured as F0 (F-α) Reading

Abstract: Chlorophyll fluorescence was studied as a rapid technique to detect weight loss of table grape cultivars "Thompson and Flame seedless" under air storage conditions (20°C) and in a 0oC cold room. Grape clumps ( ca . 1kg) were divided into 12 groups (six for each cultivar) and initial fresh weight, soluble solid content, titratable acidity, pH and color values were recorded. Three groups were placed inside ventilated baskets with a HarvestWatch sensor facing down on the grapes and placed in a 20oC room in front of a forced air fan. These samples were used to generate continuous recording of F-�. The other groups were handled in a similar manner and were used to generate weight loss. The control treatments were held in a 0oC cold room and constantly measured by a HarvestWatch sensor. F-� (F 0) ratio curve for Thompson generally declined over times, and the rate of reduction was maximal between days 1 and 6 which is equal to ca. 20 percent in weight loss. The response for Flame grapes was almost the same as for the Thompson cultivar. There were good relationships between F-� values and weight loss values for both cultivars. From these relationships it appears that, for both cultivars, at about 20% weight loss (equal to 0.8 weight loss ratio), the F-� value stopped its decline. The other fruit quality such as SSC, TA, pH and color value indicated that the drying treatment affected these responses, compared with the fruit in the control treatment. Our results indicated that chlorophyll fluorescence techniques can detect weight loss in grapes after harvest, and thus has a potential as a rapid and non-destructive method for monitoring fruit weight loss and senescence in grape during storage.

Reproduction of the White Tip Nematode (Aphelenchoides besseyi Christie, 1942) in Different Monoxenic Cultures

Abstract: The reproductive range of the Iranian population of white tip nematode in rice, Aphelenchoides besseyi, was investigated in vitro to find out a suitable medium as well as a favorable fungal host for monoxenic culturing this nematode. Studies were carried out on rice seed associated fungi, pathogenic fungi and one mushroom (Agaricus bisporus) grown on three culture media, RPA (rice polish agar), OMA (oat meal agar) and PDA (potato dextrose agar). The nematode showed the greatest multiplication on Fusarium verticillioides, F. proliferatum, Curvularia lunata and Magnaporthe salvini in OMA and on Alternaria alternata, Bipolaris oryzae and Pyricularia oryzae in PDA. Among the fungi, tested A. alternata, C. lunata, F. verticillioides, B. oryzae, M. salvini, F. proliferatum and P. oryzae supported a high reproduction rate in the nematode in a descending rank. The nematode failed to multiply on Aspergillus niger, Rhizoctonia solani and Agaricus bisporus grown on any of the three media. The highest sex ratio (F:M) was achieved on OMA but the highest male percentage ratio was observed on PDA. The two pathogenic fungi, B. oryzae and M. salvini are reported as new fungal hosts for monoxenic culturing of this nematode.

Cloning of a Methyl Parathion Hydrolase Gene from Ochrobactrum sp.

Abstract: Organophosphorus(OP) compounds which are widely used as high efficient and broad-spectrum insecticides caused broad-area pollution to environment.A bactrium with high efficient capability of degrading methyl parathion,identified as Ochrobactrum sp.by 16S rDNA analysis,is isolated from highly OP-polluted soil in this study.The full-length mphxw gene from this bactrium is cloned by PCR.The prokaryotic expression vector is constructed and the expressed products bore normal bioactivity in E.coli.The methyl parathion hydrolase MPD is purified.

A Simple and Versatile Protocol for Isolation of RNA from Plant, Fungi and Animal

Abstract: Compared to other plants, the traditional protocols for RNA isolation from sugarcane (Saccharum) are usually deficient and result in poor yields, or low-quality. Here we describe a modified method for isolating RNA from various tissues of S. officinarum, in which only Trizol and some routine reagents were needed. The absorbance at 260/280 nm ranges from 1.70 to 1.80, indicating that the quality of RNA is high, as confirmed by double-stranded cDNA synthesis and reverse transcription-polymerase chain (RT-PCR). This protocol can also be used effectively in RNA isolation from Erianthus arundinaceus, rice (Oryza sativa Linnaeus), Achyranthes, Sporotrichum spp., Thermophil and loach (Misgurnus anguillicaudatus).

Effect of Genotype Variability on Nitrate Uptake and Assimilation of Wheat Cultivars

Abstract: Nitrate concentration of the soil, at the start of growing season, is high due to mineralization of soil organic N during the Fall and the addition of N fertilizers. It may be useful to exploit this N form as much as possible. Therefore, the nitrate uptake, assimilation and dry matter production of several wheat cultivars were examined in a series of experiments using a hydroponic culture system. Seedlings were grown at two rates of nitrates (0 and 1.0 mM) and the experiments lasted for 26 days. Significant genetic variation in the growth and nitrate uptake were observed. The Atila and Yavarous cultivars consistently produced large seedlings absorbing higher quantities of nitrate from the nutrient solution, compared to the Falat, Star and Seri 11 cultivars which produced smaller seedling and took up lower amounts of nitrate. However, apart from seedling vigor, there was evidence that some cultivars were more efficient physiologically in assimilating nitrate. For comparable amounts of nitrate taken up from solution, total dry matter production in this group of cultivars was considerably greater than others. Results of this work revealed that genetic differences among wheat cultivars affect nitrate uptake, which in turn indicated the influence of plant status and in particular root system on the potential of nitrate uptake.