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Lipase is used in the production of detergents, cosmetics, pharmaceuticals, flavour enhancers and foods. The lipase of yeast Yarrowia lipolytica can be used for production of important class of chemical intermediates in the pharmaceutical industry. Lipase production depends on media composition and environmental conditions. Y. lipolytica DSM 3286 strain was cultured on media containing different organic and inorganic nitrogen sources. Lipase production was investigated by measuring biomass and lipase activity was detected by ρ-nitrophenyl laurate (PNPL) spectrophotometric assay method at various times within a period of 7 days. In this study, the effect of different nitrogen sources was investigated on Y. lipolytica DSM 3286 lipase production. The maximal lipase production (34.7 U/ml after 48 h) was detected in medium containing yeast extract as nitrogen source. The optimum temperature and pH of the enzyme activity were 37 °C and 7, respectively. The final goal of this study is to develop and optimize lipase production by Y. lipolytica for use in pharmaceutical industry.

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In order to investigate the Effect of different levels of nitrogen and plant density on yield, and some morphological sunflower cultivars, experimental farm in 2009 in the College of Agriculture University researcher Ardebili A split plot factorial design based on a randomized complete block with three replicates was carried out. Nitrogen treatments included (zero, 75 and 150 kg per ha) assigned to main plots and levels of plant density (8, 10 and 12 plants per square meter) and two varieties were Urofelor and Armavirsky in sub plot. Head and stem diameter, plant height, number of kernel per disk, number of leaves at the final of harvesting and grain yield measured. Sunflower cultivars was significant difference on the stem diameter, plant height and number of kernel per disk but different levels of nitrogen and plant density were significant difference on the for all traits measured. The highest grain yield was obtained, 262 gr /m2 in 150 kg N/ha× Armavirsky. Increasing plant density by increasing the number of heads per unit area, will affect performance. Considering the excellence level of 80 thousand plant density and fertilizer level of 150 kg ha compared to other treatments in terms of grain yield, the amounts of nitrogen and planting density to achieve adequate performance in the test area and similar areas is advisable.

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The total nitrogen content of three barley cultivars: Cehada Capa (resistant at 25aC), Cl 1243 (resistant at 5°C) and Rika 1 (susceptible at all temperatures) to Puccinia hordei was determined and compared in healthy and infected plants at 5° and 26°C. The results indicate that the total nitrogen content of cv. Cehada Capa leaves was greater than that of Cl 1243 and Rika 1 and that of Cl 1243 was greater than that of Rika 1 when plants were grown at 26°C. When plants were grown at 5°C, the percentage of total nitrogen content of leaves of cv. Cebada Capa was significantly greater than that of Cl 1243 and Rika 1, but no differences were found between Rika 1 and Cl 1243. It was concluded that the total nitrogen content has no role in the temperature sensitivity of barley cultivars. In most cases, especially in susceptible cultivars, the nitrogen content of infected leaves was greater than that of healthy plants when plants were incubated at 26°C, but there were no significant differences between total nitrogen content of infected leaves and that of their healthy control when plants were incubated at 5°C.

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Abstract
Research subject: In recent years, many efforts have been made to improve the performance of polymer membranes in oxygen-nitrogen separation due to the high cost and energy consumption of cryogenic distillation and adsorption methods. Increasing the performance of these types of membranes is still needed for industrial applications.
Research approach: In this research, novel magnetic mixed matrix membranes (MMMs) were prepared using polysulfone (PSf) as the main matrix, and also neodymium (Nd) as the magnetic particles for O₂/N₂ separation. To avoid the particle sedimentation and proper dispersion of particles across the membrane thickness, magnetic particle dispersion in the PSf was controlled by applying an external magnetic field (MF). The effect of Nd magnetic particle content on the microstructure, magnetic properties and thermal stability of the prepared MMMs were investigated using scanning electron microscopy, vibrating sample magnetometer and thermo-gravimetric analysis. In this reseach, a novel magnetic module was designed and constructed to investigate the performance of prepared membranes in the presence of various MFs.
Main Results: The obtained results indicated that the permeability of O₂ and N₂ gases was improved by adding Nd magnetic particles into PSf matrix regardless of the amount of MF due to the chain packing of polymers disruption and free volume enhancement. The permeability of O₂ and N₂ in the MMMs containing 5 wt.% Nd in the absence of MF was about 182 % and 443%, respectively, higher than those of neat PSf membranes. Furthermore, the permeability and selectivity of PSf and PSf-Nd membranes were considerably improved by applying the MF during the permeation experiments. In the MMMs containing 5 wt.% Nd, O2/N2 selectivity was increased from 2.73 to 3.77 upon an increase in the intensity of MF from 0 to 570 mT. Considering the findings, the application of Nd particles and MF during the membrane preparation and separation processes can be facile methods for enhancement of membrane performance.
 
Keywords: Oxygen/nitrogen separation; Polysulfone; Neodymium; Magnetic mixed-matrix membranes; Magnetic separation module
 

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Background: Measures of nutrient availability such as concentrations of carbon (C), nitrogen (N) and phosphorus (P) are important indicators of terrestrial ecosystems productivity. Current research illustrates the C, N and P stoichiometry of litter and soil in a coastal mixed forest stand, northern Iran.
Materials and Methods: To this, the Carpinus betulus (CB), Acer velutinum (AV), Pterocarya fraxinifolia (PF), Quercus castaneifolia (QC) species were considered; litter and soil (0-15cm depth) samples were taken under tree canopy cover.
Results: Litter and soil C: N ratio differed among the tree species, showing the highest (61.08 and 31.44) and lowest (21.90 and 3.59) under the QC and CB tree species, respectively. The litter and soil C: P ratio varied among the study sites and ranked in order of QC (52.4 and 27227.04) > PF (30 and 1465.61) > AV (15.74 and 630.54) ≈ CB (13.42 and 566.28). The higher amounts of litter N: P ratio were significantly found under QC (0.86) > PF (0.73) > CB (0.61) ≈ AV (0.55), whereas soil N: P ratio were significantly higher under CB (177.69) > PF (123.53) ≈ AV (121.60) > QC (109.25), respectively.
Conclusion: We found the species that differed in traits could influence C, N and P dynamics and its stoichiometry. The Q. castaneifolia species with different root traits that resulted in different vertical and horizontal distributions of C, N and P, reflecting differences in nutrient uptake by plants and microbial dynamics, drove the biggest changes in litter and soil C, N and P.

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Eighteen crossbred Swifter (Flemish ♀ X Texel ♂) male lambs, born in March 1997 and weaned at the age of approximately 3 months, were used to quantify effects of feed quality restriction and realimentation on changes in energy and nitrogen metabolism. The ration consisted of grass straw (17 MJ of GE and 46 g CP per kg DM) on an ad libitum basis and 35 g.kg-.75d-1 mixed concentrates (16.5 MJ of GE and 173 g CP per kg DM). At the age of approximately 3.5 months, the animals were randomly divided into six blocks, based on live weight, according to a randomized complete block design. Within each block, the animals were randomly assigned to two restricted treatments (R1 and R2) and a control treatment. Treatments R1 and R2 were subjected to feed quality restriction by withhold-ing concentrate for 3 and 4.5 months, respectively. A modified linear model was devel-oped to study the effects of restriction and realimentation. The comparison between treatments was made by analyzing the data of R1 and R2 animals as deviations from the control animal in each block. During the restriction period, restricted animals lost weight and showed a negative EB and NB, whereas their intake from low-quality roughage sig-nificantly (P < 0.001) increased. After realimentation, the R1 and R2 animals grew signifi-cantly (P < 0.001) faster than the C animals. The realimented animals persisted in ingest-ing more (P < 0.001) low-quality roughage and their EB and NB were greater (P < 0.001) than those of C animals. The R2 animals needed a longer period of realimentation be-cause of a longer period of restriction. The expression of compensatory growth was mainly related to a sustained higher (P < 0.001) grass straw (low-quality roughage) intake during realimentation periods, and greater (P < 0.001) efficiency of metabolizable energy intake. The maintenance requirement of realimented animals was lower (P < 0.001) only during the initial stages of realimentation compared with controls.

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In recent years, air separation using membranes has received much attention as a cost-effective technology for producing relatively pure streams of nitrogen and oxygen. The results of studies show that the design and fabrication of new polymers with the desired structure for the industrialization of polymer membrane technology in the field of oxygen separation from nitrogen is considered very important. The results obtained from various research works show that polymer membranes made on the basis of aromatic polyimides and PIMs due to high selectivity, suitable mechanical, thermal and chemical properties and also benefiting from different structures due to polymer substitutions are a suitable option for separation of oxygen and nitrogen. Moreover, the membrane modification process can greatly increase the mechanical, chemical and selectivity of the membranes and be an effective way to improve the separation of oxygen from nitrogen. The results indicate that the fabrication of blended membranes has increased the selectivity and permeability of the membranes, and the creation of transverse connections in most cases has increased the selectivity of the membranes. Meanwhile, carbon molecular sieve membranes that are made by thermal decomposition of the polymeric raw material under controlled temperature and pressure conditions due to their properties such as high selectivity and permeability, stability in corrosive environments and applicability at high temperatures are suitable options for separation of oxygen and nitrogen. Also, carefully in the results obtained from various research works, it can be seen that the use of driving force and magnetic particles in the polymer simultaneously improves the permeability and selectivity of membranes. As it is predicted, this method is one of the efficient methods in improving the performance of polymer membranes in the field of oxygen and nitrogen separation.

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Research topic:
Gas lift is an efficient artificial lift strategy, routinely used to overcome the low productivity of the wells. In this research, the possibility of using two gases, carbon dioxide and nitrogen instead of natural gas, in the gas lifting process is investigated and compared. To maximize oil production, the optimization of the allocation of the limited amount of gas between 10 wells in the Iranian offshore brown oil field is performed.
Research Method:
In this research, all the wells were modeled by PROSPER software. First, all 10 wells data of an Iranian offshore oil reservoir were collected. Secondly, their model has been built and after validation, a simulation of the artificial gas lift was performed using carbon dioxide and nitrogen gas separately, then, the Gas Lift Performance Curve (GLPC) of all the wells are fitted with the appropriate experimental model in MATLAB software. In the following, using Solver Excel, the allocation optimization with a limited amount of gas was performed using two different gases.
Main results:
According to the results obtained from the optimization, for a certain amount of available gas which is 15 MMSCFD, the total Oil production in the case of nitrogen gas injection is 3564 STBD more than carbon dioxide gas injection. Also, in all cases, due to the production potential capacity of well No. 8, the most amount of injected gas is allocated to it. The comparison of the two types of injected gas shows that the quantity of oil produced using nitrogen is 3424 and 3302 STBD (28 % and 24 %) greater than carbon dioxide gas when the gas is lowered to 12 and 9 MMSCFD, respectively.
 

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Effect of gamma irradiation on total volatile base nitrogen (TVB-N) and sensory evaluations of Indian white shrimp (P. indicus) held frozen (-18˚C), for 9 months and every 1.5 months, was studied. TVB-N values increased gradually during the storage period rn and decreased with increasing irradiation dose that reached 20.64, 27.45, 34.14, 35.45 mg N/100g flesh, respectively for irradiated and control samples. Also with organoleptic evaluation indicated that, shelf-life of 5, 2.5 KGy samples increased up to 3 months and 1 KGy samples increased up to 1.5 months compared to control samples. rn  

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To study the effects of plant density and nitrogen rates on the ability of canola (Regent  Cobra; an inbred variety) to compete with weeds, an experiment was conducted as a factorial complete block design with four replications. The treatments included four levels of plant density at 150, 190, 230, and 270 plants m-2, and four levels of nitrogen (N) fertil-izer at 0, 46, 92, and 138 kg ha–1. Results indicated that different levels of plant density and N fertilizer had significant effects on the canola’s leaf area index (LAI) and dry mat-ter accumulation, as well as on the weed’s dry matter at three stages of plant growth (ro-sette, stem elongation, and 50% flowering). The addition of N fertilizer resulted in in-creasing plant LAI and decreasing weed dry matter. Densities of 150 and 270 plants m-2, along with 138 kg ha–1 nitrogen showed the highest LAI at the rosette and stem elongation stages. The LAI at different plant growth stages was an important factor in enhancing ca-nola’s competitiveness with weeds. There were significant differences between different plant density and N fertilizer levels for traits such as plant height, pod bearing stem length, biomass and seed yield. An increase in plant density significantly decreased the pod bearing stem length and total pod numbers per plant (i.e. pod numbers in main branches and sub-branches), but increased plant height. The highest seed yield was ob-tained with 190 plants m-2 along with 138 kg N ha–1. This study revealed that optimum plant density as well as N fertilizer may increase the competitive ability of canola against weeds.

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The objective of this research work was to study the effect of Rhizobium leguminosarum pre-induced with genistein (G) and methyl jasmonate (MJ) on nodulation, nitrogen fixation and early growth of the common bean (Phaseolus vulgaris L.). Four day-old seed-lings were transferred to pots, containing sterilized sand and turface (2:1 v:v) mixture and, receiving Hoagland’s nutrient solution, without nitrogen. The plants were grown in a growth chamber using a randomized complete block design with six replications. The rhizobia were cultured in TY medium and incubated with G, and/or MJ. The incubated rhizobia were used after 24 hours to inoculate the bean seedlings. The results showed that both G and MJ enhanced the nodule number, nitrogen content per plant, and plant dry matter. Genistein and MJ, when applied together to cultures, showed synergistic effects on all the characters studied. The results of this study indicated that MJ alone, or in com-bination with G, can be used to promote bean nodulation, nitrogen fixation and early plant growth.

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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 ex-periments 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, increas-ing nitrogen fertilizer caused a decreasing trend in the biological efficiency of intercrop-ping. 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 inter-cropping vetch and barley had the highest productivity and crude protein yield.

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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 accumu-lating 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 parti-tioning 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, Shi-raz 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, com-pared 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 benefi-cial interactive effects of PGRs and nitrogen rates on winter wheat yield are worthy of further exploration.

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Most areas of the world where rainfall is limiting are characterized by low agricultural output and, ironically, high population growth rates that generate increased food de-mand. Arid and semi-arid regions permit a range of vegetative biomass production, from rainfed crops to native pasture, and sparse steppe shrubs to true desert. Given the harsh climatic conditions in areas such as West Asia-North Africa, where less than 10% of the land area is amenable to rainfed cropping, soil resources are fragile and cropping condi-tions precarious. Yet with appropriate manipulation of soil fertility and crop management within a systems context, including breeding of improved cultivars, conservation tillage, and rotations, substantial production increases can occur at the farmer's level. While irri-gation has increased considerably in the past few decades, having a major impact on crop yields, surface and ground water sources remain limited. Applied research specific to the region has shown that crop output can be considerably enhanced with adequate nutrition, most of which has to be added as commercial fertilizer. The substantial yield increases that have taken place in several countries of the region have been attributed to three fac-tors: water, fertilizers, and improved varieties. Technologies that potentially produce such high yield increases include identification of nutrient stresses and taking corrective action, and, where appropriate, adapting the plant to the soil conditions. If managed properly, innovative cropping systems to overcome these constraints can improve rather than de-grade soil conditions. Regardless of the advances in biotechnology, crop adaptation, and integrated cropping systems, chemical fertilizers will, in future, play an even greater role in the nutrition of both rainfed and irrigated crops in Mediterranean agriculture. Crop nutrition research will have to keep pace with agronomic developments. The future chal-lenge in soil fertility-crop nutrition lies as much in overcoming obstacles to technology transfer as in the generation of new knowledge. This selective review is based mainly on the author’s research experiences in the field of soil fertility and crop nutrition in the WANA region for the past 32 years. It seeks to highlight research developments within the context of the region's crop production constraints, culminating in a perspective on future research challenges within the framework of cooperation between international in-stitutions and the region’s national research and development programs.

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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 ni-trification 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-1soil), 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 com-pletely 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 concentra-tion 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.

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Measuring total microbial count of poultry meat with conventional pour plate method and comparing the results with standard limits is one of the routine tests. Achieving the results of total microbial count in minimum time is really important for confidence from the hygienic quality of products. So impedance – splitting method as a new technique for this purpose was considered in order to receiving the results in a shorter time and as soon as possible. The main purpose of this study, was to evaluate the correlation between impedance detection time (IDT in hrs), total microbial population (log₁₀ N) and total volatile nitrogen (TVN) of poultry meat fillets. Totally 80 samples (40 samples in warm season and 40 samples in cold season) were collected and examined under sterile conditions. The total microbial count by pour plate technique and impedance – splitting method, also measuring total volatile nitrogen were carried out based on the recommendations of Iran's Standard Institute and Industrial Investigation. Then the calibration curves of 3 methods and their equations were obtained by using Excel software.  The calibration curves of methods were elaborated for total microbial count and impedance detection time, demonstrating a good correlation between the two methods in cold and warm season and also all of samples equal to 98.1%, 97.3% and 97.4%, respectively. Also according to the calibration curves, the correlation between impedance detection time and total volatile nitrogen in cold and warm season and also all of samples were equal to 81.5%, 85.4% and 82.5% respectively. Also the correlation between total microbial count and total volatile nitrogen in cold and warm season and also all of samples were equal to 83.2%, 86.8% and 84.4%, respectively for poultry meat samples. Therefore, impedance measurement which is a more rapid, automated and less laborious method than conventional technique could be used as an alternative method for the rapid quality evaluation in foods instead of conventional methods.  

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The West Asia-North Africa region, which is characterized by a typical Mediterranean climate, is the center of origin of cereals, notably wheat (Triticum spp.) and barley (Hordeum spp). However, cereal production, which is primarily rainfed, is mainly constrained by drought due to the low rainfall accompanied by high temperatures. Cereals have been tradi-tionally grown following a fallow period in order to achieve acceptable yields on stored soil moisture, but they are increasingly grown either continuously or in rotation with legumes, either food or forage. Barley is grown throughout the Mediterranean region, generally in the drier zones and often on shallow soils and with application of minimum or no fertilizers. The medium-rainfall zone of central Morocco (200-500 mm yr-1) is typical of the region as a whole. In order to provide a rational basis for barley fertilization, especially as regards ni-trogen (N), a field trial was established near Settat, involving five barley varieties (ACSAD-60, Tessaout, Asni, Arig-8, and ACSAD-176), along with four N application at four levels (0, 40, 80, and 120 kg N ha-1), grown on a shallow soil (Petrocalcic Palexeroll) for two growing seasons that varied in terms of total rainfall (Year 1, 261mm and Year 2, 302 mm) as well as within-season distribution. There were considerable differences between crop years, with significantly higher yields in the second growing season when rainfall was heavy at the criti-cal tillering and stem-elongation growth stages. Nitrogen consistently increased dry matter and grain yields in either year, generally being significant up to 80 kg ha-1. There were sig-nificant differences observed among varieties, as well as interactions of varieties with years. The six-row variety Arig-8 was consistently the best while the two-row Asni, the lowest yielding variety. Where an economic analysis was done on yield data (Year 1), N fertilization up to at least 80 kg ha-1 was considered as profitable. Crop N uptake varied with varieties and increased with increasing fertilizer. N Recovery was variable and generally less than 50%. In contrast to many other fertilizer trials with barley in the region, this trial from cen-tral Morocco showed highly significant yield increases in response to applied N for barley varieties, most of which performed similarly. Therefore, N fertilization of barley in Mo-rocco’s semi-arid cereal-producing zone on shallow soils, where root growth and moisture-holding capacity are limited, should be promoted.

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Aims: Despite the many studies on carbon stock and sequestration in Iranian forest ecosystems, the effects and role of Mediterranean species on carbon stock in Iranian forest ecosystems are not well known. To our knowledge, no information is available on the carbon sequestration of Mediterranean species in Iran. This study aimed to quantify the surface soil carbon stock of Mediterranean tree species in the Zagros forest. 
Materials & Methods: To this, ten soil samples were taken under the canopy of Cupressus sempervirens var horizontalis, Myrtus commonis, Quercus brantii, and also bare lands from a depth of 0-20 cm. Soil carbon stocks were calculated in each of the studied treatments. One-way ANOVA was used to evaluate the differences among the studied species and bare land for soil physiochemical properties and carbon stock. Multiple linear regression (MLR) using the stepwise method was performed to define the most critical soil factor for soil carbon stock calculation. 
Findings: Our results indicated that Cupressus sempervirens represent the highest significant value for soil carbon stock (237.79 t.ha-1). Soil carbon stock in Myrtus commonis and Quercus brantii stands were 122.05 and 91.90 t.ha-1, respectively. Significant differences between Myrtus commonis and Quercus brantii were recorded. The lowest soil carbon stock was recorded in the control site and was significantly lower (27.26 t.ha-1) compared to the other treatments. Compared to the bare land and Quercus brantii stand, Cupressus sempervirens had 872.30 and 258.74 percent higher soil carbon stock, respectively. The higher soil nutrient content under the Mediterranean canopy is due to the higher soil nutrients available. Also, it might be related to the protection made for these species compared to the oak forest. Moreover, soil organic carbon and bulk density represent the best predictors of the soil carbon stock based on the multi-linear regression method. 
Conclusion: Reforestation/afforestation programs using Myrtus commonis and Cupressus sempervirens should also be considered for carbon sequestration programs in the Zagros forest, where these species could be planted. Moreover, our results demonstrate that using a variety of tree species, primarily Mediterranean species, would be a proper policy for increasing soil carbon stock in the Zagros forest.
 

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A two year field experiment was carried out to evaluate the competitive effects of wild mustard densities growing with rapeseed (cultivar Talaye) under different nitrogen rates. Treatments were wild mustard densities (0, 10, 20, 30, and 40 plant m-2) and nitrogen (N) rates (0, 50, 100, 150, and 200 kg N ha-1). The factorial set of treatments was arranged into a randomized complete block design with four replications. Rapeseed yield and the yield components decreased as wild mustard density increased. At 0 and 10 wild mustard plants m-2, grain yield increased with increasing N fertilizer up to 150 kg ha-1. At higher wild mustard densities, grain yield decreased above 100 kg N ha-1. These results indicate that increases in nitrogen application only increased the competitiveness of the weed versus the crop.