جستجوی مقالات مرتبط با کلیدواژه « دی اکسید کربن » در نشریات گروه « کشاورزی »

This research was done with the aim of checking energy and economic indicators and the amount of greenhouse gas emissions in the production system of two products, tomato and onion in 2021 and 2022 in Alborz province. The information required for this research was obtained through interviews with farmers and completing questionnaires. The results of this study showed that the highest energy input, energy output, and net energy in onion were obtained in Savojbolagh city at the rate of 21324.8, 105600, and 24275.3 Mj.ha-1, respectively. In tomato, the highest input energy, output energy, and net energy was 73799.8, 56000, and -13495.4 Mj.ha1, respectively (in tomato, net energy is negative due to the greater input energy than output energy). The highest energy efficiency consumption was obtained in onion and tomato, 1.4 and 1.32 respectively. In the comparison of energy efficiency, the highest value in onion and tomato were observed 0.82 and 0.99 Kg.mj-1. Among the various inputs in the onion and tomato production systems, diesel, nitrogen chemical fertilizer, animal manure, irrigation water, gasoline, and manpower had the largest share in input energy in the order of priority. Onion and tomato by producing 3065.8 and 3045.4 kg of CO2 per hectare, played a role in the emissions of greenhouse gases. The analysis of economic indicators also showed that onion with a net income of 9608.7 $.ha-1 compared to tomato with a net income of 4840.3 $.ha-1 has generated more income. According to the obtained results it can be possible that reduce the amount of energy input and greenhouse gas emissions and thus, provide the necessary conditions for the establishment of more sustainable agriculture by modifying production methods such as using modern irrigation methods and also replacing animal and biological fertilizers with chemical fertilizers.

This study was conducted to investigate the ability of carbon sequestration in barley and to determine the global warming potential of this product in the cropping year 2020-2021 in rural areas Shirvan city. For this purpose, systematic random sampling was performed in 30 farms from 0-30 cm soil depth and consumption inputs were obtained through face-to-face questionnaire. The results showed that the soil carbon sequestration capacity in barley farms was equal to 1.74 ton/ha-1. Comparison of conversion coefficient of plant organs showed that spike had a higher conversion coefficient of 22.4% than root. The carbon sequestration capacity of spike, stem and barley root was determined as 1297.20, 620.62 and 114.00 kg.ha-1, respectively. Among the inputs, diesel fuel with an average of 552.70 kg.ha-1 had the highest role and electricity with an average of 6.85 kg.ha-1 had the least role in greenhouse gas emissions. Among greenhouse gases, carbon dioxide with 1135.79 kg.ha-1 had the highest share. The total global warming potential of one hectare of barley in Shirvan city was 1147.31 kg equivalent of carbon dioxide. The amount of carbon footprint obtained for the total plant biomass was equal to 0.28 kg equivalent to carbon dioxide per kg of barley biomass. In general, the obtained results showed that the barley product has an acceptable carbon sequestration capacity and is a suitable crop to be included in the model program of rural areas. Based on the results of this research, part of the gross production of rural areas of Shirvan city will be achieved through the cultivation of barley in marginal lands with low production capacity, which will play an important role in the development of these areas.

Soil microbial respiration in forests constitutes a significant share of carbon dioxide emissions in terrestrial ecosystems and is very sensitive to environmental changes such as soil temperature and moisture and the type of vegetation. In this study, soil microbial respiration and two environmental factors including temperature and soil moisture were conducted in five forest types in four seasons. Soil microbial respiration was measured by the closed bottle method, soil moisture in the laboratory and soil temperature with a thermometer simultaneously with soil sampling in areas of surface soil (0 to 10 cm depth), and the relationships between soil microbial respiration and environmental variables were analyzed. The results showed that the soil microbial respiration rate is significantly higher in the wet period (spring). The pure Quercus libani types with an average of 0.090 throughout the year had the highest amount and the pure Q. infectoria types with an amount of 0.078 mg/g of soil per day had the lowest amount of microbial respiration. Also, no significant difference was observed in soil microbial respiration between forest types.

Global warming has already been occurring in Iran and will probably continue during the 21st century. There has been an increased intensity and frequency of hot daytime temperatures in the last two decades in the country. Winter wheat (Triticum aestivum L.) is the most important staple food crop in the country, with a total farming area of nearly 6.33 million ha and a production exceeding 14 million tons in 2017. Wheat production in Iran is an important component of national food security. The crop is grown almost all over the country under varied soil and climatic conditions. Most parts of Iran have an arid and semi-arid climate with long dry summer and winter rainfall, which climate change may negatively affect wheat production sustainability in these vulnerable environments. Wheat is a thermo-sensitive crop, and a change in air temperature may alter the length of its growing period and grain yield. Wheat production mainly depends on the duration of the reproductive period; thus, precise crop phenology estimation is essential for yield prediction under current and future climate conditions. The variety of C-84-8, which is named "Mihan," was introduced from the cross between the domestic variety “Barkat” and the Chinese variety “Zhong87-90” in Karaj for normal irrigation conditions and drought stress after the flowering stage in the cold regions of Iran in 2009. Mihan variety is known as a high yielded potential. The actual yield of this variety in Ardabil province has been reported between 8.13 to 10.31 tons per hectare.

The aim of this study was to simulate the climate change effects on the growth period, LAI, and biological and grain yield of wheat (Mihan variety) in the Kerman and Ardebil regions. For this purpose, we employed the HadGEM2-ES model as affected by two RCP4.5 and RCP8.5 scenarios for two time periods, 2021-2055 and 2056-2090. MarkSIMGCMmodel was used to produce daily climatic parameters as one stochastic growing season for each projection period, and the CERES-wheat model in DSSAT software was used to simulate wheat growth. Calibration and validation of the model in Kerman were performed with two-year experiments designed at the Shahid Bahonar University farm in Kerman, and for the Ardabil region, it performed with the data of the wheat projects of the Agricultural Research and Training Center and Natural Resources of Ardabil province.

The results of the model evaluation showed that MarkSIMGCM had an appropriate prediction for simulating climatic parameters and stochastic growing seasons in future climate change conditions. In both studied regions, the RCP8.5 scenario has a higher temperature and radiation increase than the RCP4.5 scenario, and these changes are greater in the long-term period than in the short-term period. Rainfall changes in both investigated regions did not show a regular trend. The growing period length was reduced by 0.51% -4.59% as affected by various climate change scenarios and periods. In the near period time (2055), simulating results showed that wheat grain yield would decrease by 3.87% compared to the current condition based on the RCP4.5 scenario. But, the traits will be increased by 0.99%-15.15% according to the RCP8.5 scenario in Kerman and Ardebil based on both scenarios. In the far period time (2090), the grain yield for the Kerman region will respectively decrease by -7.39% and -36% according to both RCP4.5 and RCP8.5 scenarios compared to the current time, and in Ardabil, based on the scenario RCP4.5 will be improved by 20.36%, and it will be declined by -2.89% according to the RCP8.5 scenario. This indicates that the negative impacts of warming will outweigh to the positive effect of CO2 enrichment over time.

In general, the results confirmed that the Mihan variety would produce acceptable grain yield in the future climate change conditions of Ardabil, but in Kerman, mitigating strategies should be considered to adapt wheat to the adverse impacts of climate change.

Increasing concentrations of greenhouse gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) in the atmosphere and the consequent climate change have irreversible effects on the environment and human health. Greenhouse gases in the soil are produced by microbial activity, root respiration, chemical decomposition, and heterotrophic respiration of organisms; the carbon flux from the soil in the form of carbon dioxide is caused by respiration and other activities of soil organisms, nitrous oxide is produced by nitrification and denitrification processes, and methane is produced by microbial methanogenesis under anaerobic conditions. This is while various environmental and managerial factors might affect their concentrations in the soil. Proper management of agricultural soils offers a significant potential to reduce greenhouse emissions. For instance, crop rotation, cover crop farming, conservation tillage, crop residues retention, and avoiding plant residue burning or removal serve as appropriate management practices to reduce carbon dioxide emission. Strategies employed to mitigate nitrous oxide emission include better nitrogen management, well-planned application of nitrogen fertilizers only to meet crop requirements in a timely manner, reduced application of nitrogen fertilizers tailored to the different stages of plant growth, using Legume plants in crop rotation, proper crop residue management, use of slow-release fertilizers, and application of nitrification and denitrification inhibitors. Methane emissions may be reduced through drainage of rice paddies to provide adequate ventilation for methane oxidation and tillage or composting to decompose crop residues before flooding.

To investigate the effect of foliar application of calcium carbonate nanoparticles (CCN) and indirectly increasing carbon dioxide concentration on salt stress modulation of rose 'Dolce Vita., a soilless culture experiment was conducted as a randomized complete blocks design with three replications, in which the pots were filled with a mixture of cocopeat and perlite. The first factor was salinity at two levels (1.8 and 3.2 dS m-1 by adding NaCl to the nutrient solution) and the second factor was foliar spraying of CCN at four levels (0, 3, 6 and 9 g L-1 by using Lithovit fertilizer). Increasing salinity and the concentration of CCN had no effect on potassium and sodium contents of leaves and electrolyte leakage of leaf cells. The salinity of 3.2 dS m-1 reduced the relative humidity of leaf and increased the dry matter percentage and soluble sugar content in the plant leaves; however, had no significant effect on studied morphological characteristics. The application of CCN significantly increased the relative humidity of leaves in both saline and non-saline treatments and the mean of morphological traits (leaf area, flower diameter, stem length and flower yield). In addition, the application of 6 and 9 g L-1 CCN significantly increased the concentration of chlorophyll, carotenoid, and leaf soluble sugar; however, salinity had no effect on these characteristics. Results showed that foliar application of CCN, by affecting physiological and morphological traits and improving plant nutrition, modulates salinity stress and improves the growth conditions of Dolce Vita rose.

In the recent years, agricultural products packaging was faced with some challenges. One of these challenges is measuring the oxygen and carbon dioxide amount during the respiration of stored products. Due to the high cost of the sensors and measuring devices of oxygen and carbon dioxide, the researchers have been looking for alternative methods for those measuring. The major aims of this study is to find a mathematical measurement method based on temperature, humidity ratio, and absolute and differential pressure during the respiration of lettuce storage. The present study was conducted at three temperature levels (5, 15, and 25 °C) and three storage time levels (24, 48 and 72 h). Based on the results of the mathematical model, the accuracy of prediction at the storage temperature of 5, 15, and 25°C for oxygen measurement were 96%, 98% and 97% and for carbon dioxide measurement were 95%, 99% and 98%, respectively. The statistical analysis of the variation parameters of carbon dioxide, humidity ratio and absolute and differential pressure with the variation of temperature and storage time of lettuce was significant at 1% levels.

The CO2 emission is one of the components of global warming which has been more attention paid. Globalization as a phenomenon in the world has been affected the economic and social aspects of people. Therefore, given that globalization and the growing share of countries in the global trade network require extensive economic and productive activities, there is doubt about the impact of globalization on CO2 emissions. Considering the lack of consensus, the present study seeks to answer the question of whether globalization will increase or reduce CO2 emissions. To achieve the aim spatial panel data is used. The results of this study showed that globalization has a positive and significant effect on CO2 emissions in the MENA region. In other words, the growing trend of globalization has led to increasing CO2 emissions. Also, due to the spatial relationship between the MENA countries, it is suggested that countries begin to more cooperation and common policies in order to reduce the negative effects of economic activities on the environment.

MODIS-based Gross Primary Production (MODIS-GPP) as a proxy of the potential of vegetation cover in the atmospheric carbon sequestration was evaluated using Flux Tower measurements (Flux Tower-GPP) across three sites, broadleaved temperate deciduous woodlands, in the south of England. Ensuing to the normal evaluation of data distribution, the mean value of MODIS-GPP (cell size: 1km2) compared with the Flux Tower-GPP through the Two-Tailed T-Test (P < 0.05). A significant difference between two groups, MODIS-GPP vs. Flux Tower-GPP, was found that there is a measurable difference between the groups and that, statistically. The results show that Flux Tower-GPP values for both Alice Holt and Wytham Woods sites are higher than the MODIS-GPP, while in Pang Lambourne the opposite is true due to land cover heterogeneity. The trend of seasonal changes of both groups is the same and the increase of GPP in plant phenology is observable in all sites. GPP values gradually increase to early of May, then a prompt rising observed in May that extend to late of summer which arisen from development of solar radiation, day length and photosynthetic activity. In late of summer, GPP values gradually decrease so that by advent of autumn a rapid decline come about in the early of October that corresponds with senescence and abscission, due to decreasing temperature, which reflects the seasonal variation in terms of carbon uptake. The research finding reveals that the MODIS-GPP alone is unable to estimate accurately the potential of vegetation cover in the atmospheric carbon sequestration due to sub-pixel variability in plant functional type. On the other hand, despite at certain sites the meteorological bias influences estimates of GPP significantly and flux towers provide an excellent means to estimate accurately GPP across their footprint, they are sparse worldwide, even at the regional scale. Thus, the Flux Tower GPP may not truly be used to estimate a continuous GPP map at a larger area. Therefore, Flux Tower and MODIS individually have large uncertainty but their combination as a complementary could result in a robust estimation of GPP.

Some unit operations of food process engineering such as drying consumes a high amount of energy. Therefore, analysis of energy and exergy can be a suitable method to manage the energy consumption of the drying. Hence, in the present research, analysis of energy and exergy for the drying process of lemon verbena leaves was performed.

A cabinet solar dryer was employed to investigate the energy consumption of thin layer drying of lemon verbena leaves. The dryer had a galvanized solar plate collector which had a surface area of 0.75 m2 and to absorb the maximum solar energy, the collector painted with the black color. The collector was set at an angle of 45 degrees relative to the horizon and an electric blower was installed in the bottom of the collector to blow the ambient air through the solar collector and hence, hot air entered the drying chamber to dry the lemon verbena leaves. In order to record the air temperature and humidity in different locations of the dryer, an Arduino board with 8 smart sensors (AM2301, with temperature accuracy of 0.5°C and humidity accuracy of 3%) were used. To obtain the initial moisture content of the leaves, they inserted in an electrical oven for 16 hours at a temperature of 70°C. In order to measure the moisture content of the leaves during drying, they weighted at different times using a digital balance (A & D, Japan with accuracy of 0.001 g).Energy consumption rate of the drying was calculated by Equation (1):Where, Ein: energy consumption rate (kW), : mass flow rate of drying air (kg s-1), cp: specific heat of drying air (kJ kg-1 °C-1), Δt: temperature difference between the ambient air and drying air (°C).Also, the specific energy consumption of drying (SEC) was calculated by Equation (2):Where; SEC: Specific energy consumption (MJ kg-1 of removed water) t: drying time (s), and M: mass of removed water from the drying material (kg).Also, useful power can be calculated from Equation (3):Where; Eout: useful power (kW), ms: Evaporation rate (kg s-1), lg: latent heat of vaporization (kJ kg-1 of water)In order to calculate energy efficiency, Equation (4) was used: Also inlet and outlet exergy were calculated by equations (5) and (6), respectively: Where; T1: Inlet air temperature into the drying chamber (°C), T2: Outlet air temperature from the drying chamber (°C), T0: Ambient air temperature (°C).
Also, Equations (7) and (8) were used to calculate exergy efficiency and loss, respectively:

The results of energy analysis showed specific energy consumption (SEC) increased with increasing of drying temperature and decreasing of air velocity. Accordingly, in the air velocity of 2 m s-1 and the temperatures of 30, 40, and 50 ˚C, SEC were 276.3, 694.7, and 708.0 MJ kg-1 of removed water, respectively. While SEC for an air velocity of 2.5 m s-1 and air temperatures of 30, 40, and 50 ˚C were 266.9, 469.8, and 638.0 MJ kg-1 of removed water, respectively, the corresponded values for air velocity of 3 m s-1 were as 217.0, 391.3, and 501.8 MJ kg-1 of removed water, respectively. Also, the results revealed that with an increase of temperature and a reduction of velocity, energy efficiency reduced, so that the maximum value of energy efficiency observed in an experiment with temperature of 30˚C and velocity of 3 m s-1. Also, the highest value of exergy efficiency obtained in temperature of 50˚C and velocity of 3 m s-1.

A hot air solar dryer was used for drying lemon verbena leaves. Results of specific energy consumption of drying showed a high amount of fossil fuels can be saved by using this dryer. Also, from the aspect of energy and exergy efficiency, using of the dryer in the lower temperature and higher air velocity is recommended.

The cultivar and amount of apricot production in the East Azarbaijan province is about 28% of the total country of Iran and 30.2% of the total apricot is produced in Iran. Due to the perishable nature of apricot, it cannot be kept for more than 2-3 days at room temperature and for several days at low temperature conditions. In Iran, about one-third of horticultural and crop products are lost and destroyed annually. Important factors in increasing postharvest losses of agricultural products can be inappropriately picked up, unpurchased shipping, lack of proper keeping and packaging, and so on. This research was carried out with the aim of developing research on apricot, as well as the development of its export, by increasing the shelf life of apricot. In food packaging, the use of appropriate packaging materials, and minimizing waste and the provision of healthier and safer food products have always been considered. Various packaged packaging technologies have been developed to improve the quality and health of foods. Active packaging technologies provide new opportunities for the food industry. In recent years, the effect of modified atmosphere has been studied on the physiological, biochemical and qualitative properties of fruits and vegetables. One of the physiological effects of modified atmospheres on fruit metabolism is the reduction of respiratory rate during storage, which includes a decrease in carbohydrate metabolism, CO2 production, O2 consumption, and heat release. In climacteric fruits such as apricots, the CO2-rich atmosphere and low O2 levels reduce ethylene production. Therefore, the use of MA can increase the length of storage time of fruits. High concentrations of CO2 are effective in O2 consumption. They act as inhibitors of ethylene activity and prevent ethylene synthesis in some fruits such as apricots, avocados, pears, figs and bananas.

the study focused on reduce the production of ethylene and increase the shelf life of apricot fruit by studying the modified atmosphere packaging technology. In this project, apricot fruits of “Red Shahroud” cultivar were obtained from “Sahand Gardening Research Station of East Azarbaijan Agricultural and Natural Resources Research Center”. Packaging film of polypropylene was prepared for packing apricot fruits with 0.2 and 0.4 mm thickness from a local store. For gas injection operations, capsules containing oxygen and carbon dioxide gases (food grade) were used. The packets space were first with vacant evacuated, and then gases injected. After the gas was injected, the packages were stored in the refrigerator at a temperature of 1°C (±0.5) and cold air temperatures were kept at about 1 m/s, and every four days, tests were completed that lasted a total of 16 days. The evaluated parameters in this study were TSS, pH, firmness and EC. The MC-20181 model refract meter was used to measure TSS. For pH test, the pH meter of the metrohm-691 model was used. The texture analyser of Hounsfield-H5KS was used to measure the firmness of the apricot fruit. The EC meter ELMETRON CC 505 with an accuracy of 0.1 was used to measure EC. The experimental design was a split plot based on a completely randomized design including two plots and three replications. The main plot consisted of time in four levels (fourth day, eighth day, twelfth day, and sixteenth day). Sub plots was include the type of gas mixture used with different coatings in six levels (3% O2 + 5% CO2 with polypropylene film thickness 0.2 mm, 3% O2 + 10% CO2 with polypropylene film thickness 0.2 mm, 3% O2 + 5% CO2 with polypropylene film thickness 0.4 mm, 3% O2 + 10% CO2 with polypropylene film thickness 0.4 mm, Packaging only with polypropylene cover with thickness of 0.2 mm, Packaging only with polypropylene cover with thickness of 0.4 mm).

by increasing the storage time, the TSS was increasing. The highest amount of TSS on the 16th day was observed in polypropylene wrap with 0.2 and 0.4 mm thickness without gas composition. TSS represents the presence of small molecules such as glucose, fructose, maltose and some organic acids. By increasing the storage time of fruits, the TSS values will be increased due to the large conversion of molecules such as starch into small molecules such as glucose, maltose and dextrin, as well as reducing the moisture content of the product. On the other hand, due to reduced physiological activity of the fruit at low temperatures, the trend of the TSS will slow down. With increasing storage time, pH increased as a result of the decreasing trend of acidity. Organic acids can be considered as a source of energy stored in fruits, which decrease as a result of increased metabolism activity due to respiration or conversion to sugars. Treatment with only 0.2 mm thick PP coating showed the most effect on apricot fruit acidity, and the rest of the treatments showed an almost identical effect on acidity reduction. The treatment of 3% O2 + 10% CO2 under the cover of PP with a thickness of 0.4 mm showed the highest acidity. With increasing maintenance time, the firmness shows a downward trend. Treatment with 3% O2 + 10% CO2 covered by PP with thickness of 0.4 mm resulted in the highest firmness in apricot fruit compared to other treatments and the least firmness in non-gaseous treatment and only with a thickness of 0.2 mm was observed. With increasing storage time, the EC value also increased, but the effect of different gas constituents with different coatings and the time interaction effect with different gas mixtures with different coatings is not significant. EC shows variations in the resistance or electrical capacity that occurs as a result of changes in the concentration of soluble electrolytes when they are matured in flesh. The EC increases during fruit ripening. The incremental trend of EC extract of fruit during storage is indicative of cation leakage from the cytoplasmic membrane of fruit tissue cells, which shows the degradation of the cell membrane. This process is attributed to the ability of the pectin’s to dissolve and hydrolyse the median wall of the cell. The activity of the polygalacturonase enzyme leads to cell wall pectin hydrolysis, which seems to provide the ability to dissolve the pectin. While the pectin methyl ester enzyme regulates the attachment of cations to the cell wall and the rapid action of other cell wall hydrolysates. Therefore, cations play a key role in enzymatic activity and fruit maturity regulation.

the results showed that with increasing the of storage time, all the traits under test, namely, TSS, pH and EC, increased and fruit firmness decreased. From the point of view of the treatments used, the of type of gas mixture with different films, 3% O2 + 10% CO2 with polypropylene film thickness 0.4 mm treatments is desirable because of increased shelf life of apricot approximately 3 times. Film thickness did not significantly affect the shelf life of apricot fruit.

Water scarcity challenge and the high rate of population growth means food production needs to be increased, therefore using proper management practices which can improve water use efficiency (WUE), increase grain yield and reduce carbon dioxide emission from soil, seem to be necessary. In this research, effects of tillage systems and planting methods on water use efficiency, carbon dioxide emission from soil and wheat yield was studied at Agricultural Science and Natural Resources University of Khuzestan located in North of Ahwaz county in 2018-19. The study was conducted using a split complete randomized block design with 3 replications. Tillage at two levels including conventional tillage system (moldboard plow followed by offset disc) and minimum tillage system (combination tillage implement) as main factor and planting methods including flat and raised bed planting methods considered as sub factor. The results indicated that tillage systems and planting methods had a significant effect on water use efficiency at 5% and 1% levels, respectively. The results, also, showed that interaction of tillage systems and planting methods had a significant effect on water use efficiency at 5% level. The results related to yield showed that planting methods had significant effect on wheat yield, while effect of tillage systems and their interaction on wheat yield was not statistically significant. Minimum tillage significantly reduced carbon dioxide emission from soil compared to conventional tillage at 5% level. Although conventional tillage had a lower soil cone index at the beginning of wheat cropping season compared to minimum tillage, over time, soil cone index was approximately the same for both tillage levels. Considering the interaction effect, minimum tillage-raised bed planting treatment with a grain yield of 5426 kg/ha, water use efficiency of 1.13 kg/m3 and carbon dioxide emission of 13.33 kg. ha-1.day-1 was suggested as the best system for the studied region.

Urban forests play a key role in CO2 reduction and consequently in controlling climate change. Therefore, quantifying carbon storage is essential to understand the role of urban forests in reducing atmospheric pollution. This study quantified carbon storage in the Abidar urban forest of the Sanandaj in the Kurdistan Province. To achieve the aim, trees, leaf litter, grass biomass, and soil were sampled and analyzed. Results showed the carbon storage of 147.72 t/ha in the Abidar forest; with trees above-ground biomass, trees below-ground biomass, leaf litter and grass, and soil storing 40.29, 8.66, 1.055, and 97.72 t/ha of carbon, respectively. The results also confirmed different carbon storage levels in various species, with Robinia pseudoacacia storing more carbon in above and below biomass than Cupressus arizonica, Chamaecyparis sp., and Fraxinus rotundifolia. The results of the study could be beneficial for urban forestry, green areas management, and urban planning to foster clean air and manage greenhouse gas emissions in urban landscapes.

The main objective in agriculture production, so far, focused mostly on the increase of yield and production. Whereas today, economical and sustainable production is more important with regard to product quality, reduction of input consumption, conservation of natural resources and environment. Conservation tillage methods stabilize the soil productivity, reduce greenhouse gas emissions and protect the environment. The atmospheric concentration of greenhouse gases (GHGs) has been increased considerably in recent year's, as a result, human activities. Carbon dioxide (CO2) is the most important anthropogenic GHG; its annual emissions increased by about 80% between 1970 and 2004. Conservation tillage systems are increasingly considered as sustainable options to reduce the aftermaths of improper soil tillage. The objective of this study was to investigate energy flow and greenhouse gases emissions of sunflower production in three different tillage methods in northeastern part of Iran.

In order to evaluate the effect of three methods of sunflower production (conventional tillage and sowing, reduced tillage and direct seeding method) on energy consumption and global warming potential in rainfed conditions, this study was performed in the Kalpoosh of shahrood. Data were gathered from thirty representative fields by using a face-to-face questionnaire method and monitoring production practices and inputs used. After gathering of data, energy parameters and global warming potential were calculated based on CO2 balance. The energy amount of each input was calculated by multiplying the amount of consumed input on energy's equivalent. The output energy of sunflower was calculated by multiplying the crop yield on energy's equivalent. Other calculations of inputs and outputs in each method performed by energy coefficients.

The results indicated that total input energy in the conventional method, reduced tillage, direct seeding were 13169, 11814 and 10600 MJ.ha-1, respectively. Thus, conventional method had the highest rate of energy consumption (30 % higher than of direct seeding). Similar results reported by some researchers. The highest amount of total energy input related to nitrogen fertilizer and diesel fuel. Seedbed preparation had the highest rate of fuel and energy consumption (43.5 %) followed by nitrogen Fertilizer (37.6). Maximum of direct and indirect consumed energy, related to fuel and nitrogen, respectively. Similar results reported by some researchers. In three tillage methods, the share of irreproducible energy was the highest and small share of total energy consumption related to renewable energy. Rajabi et al. (2011) reported similar results. The energy efficiency of conventional method was less than other methods. This is due to the high share of machinery and fuel energy and greater use of workers and low yield per hectare. Reducing inputs consumption can be increased efficiency in agricultural systems. Feyzbakhsh and Soltani (2013) reported similar results. Maximum and minimum of energy productivity related to direct seeding (0.15 kg.MJ-1) and conventional method (0.11 kg.MJ-1), respectively. Maximum and minimum of global warming potential (GWP) was related to conventional method (1731 Kg.CO2 eq.ha-1) and direct seeding (1405 Kg.CO2 eq.ha-1), respectively. This issue is compatible with more fuel consumption in conventional method compared with direct seeding. In conventional method, the most rate of GWP was related to fuel consumption (44.8%) followed by nitrogen fertilizer (38.8%) and farm machinery (8.3%).

Based on this study results, through reducing of fuel consumption (replacing of obsolescent machinery and usage of modern implement, performing of farm operations in suitable soil moisture content and preventing of additional operations) and accurate consuming of nitrogen (according to soil testing), it is possible to reduce fuel consumption, greenhouse gas emission and environmental pollutions. 

The main objective of this study is to investigate the effect of carbon dioxide gas volume on the trade balance of OPEC countries with respect to the income inequality. The data of all OPEC members in a 15-year period was analyzed using the data panel approach. The results of the estimation of the import function showed with the increase in carbon dioxide emissions, the volume of imports to OPEC countries has not diminished. Due to the degree of income inequality in these countries, the increase of carbon dioxide has a significant negative relationship with the increase in import volumes. As the distance between income deciles in these countries increases, the relationship between increased carbon dioxide and volume of imports tends to reverse. The results of the export function estimation were shown the volume of exports of OPEC member countries does not have a significant relationship with carbon dioxide emissions. With regard to income inequality, there was no significant relationship between countries. Therefore, the volume of exports of OPEC member countries is independent of carbon emissions.

Fire is one of the main causes of carbon emission from forest stands. Therefore, the present study was conducted to investigate the amount of carbon emission caused by fire in the loblolly pine plantations in the Takhsam region that located in area of Lakan city of Guilan province. For this purpose, a burned region with 5 hectares’ area and a control region next to burned stand were selected and 5 circle sample plots with 4r­ (400 square meters) areas were accomplished in two stands by random-systematic method and trees diameter at breast height and total height in sample plots were taken. Then, by investigating the conducted studies Finally, 5 models selected to calculate the trees biomass in two stands. According to the results of this study, the average of trees biomass in the control stand was estimated between 93086.98 (P model) to 10536.9 kg/ha (model M) and the average of trees biomass in the burnt stand was estimated from 67829.73 (P model) to 83509.04 kg /ha (model M). The results of this study also showed that the carbon stock content in the control and fired stands was 48.853 and 38.357 tons per hectare respectively which showed significant difference in t-test. The amount of carbon emissions from the fire was 10495.69 tons per hectare and the total carbon emission at the surface of the fire spot was about 52.478 tons. Among the selected models, P model (BD = β0 β1(DBH­β2)) provided the least standard deviation in the calculations.

The reduced biomass in forests and rangelands ecosystems for any reason can affect the process of carbon sequestration and as a result of global warming. This study was conducted to assess carbon storage under different grazing intensities in rangeland of Chah Mary dominated with Artemisia siberi in Khuzestan province. Three sites under heavy, moderate and low grazing intensities were selected based on similar topographic features (slope, aspect and elevation), rainfall, soil and climate. Plant sampling was done in key areas by random-systematic method along three transects of 100m and 60 plots of 1m2. Then, aerial and underground biomass parameters were evaluated in each plot and carbon was determined by ash method. The data were analyzed by SPSS v.16 software. According to the results, carbon sequestration decreased from 5704/3 in the low-grazing region to 3470/1 in the high-grazing region. Also, under low-grazing intensity, the carbon stored in aerial biomass and underground biomass was 4360/9 and 2180/5, respectively.

Population growth and increased industrial activity in the last two centuries have led to a significant increase in atmospheric CO2 concentration. According to research, the atmospheric CO2 concentration has been increasing constantly since the industrial revolution up to recent years. The concentration has increased from 270 mg/l before industrial revolution in the mid eighteen century to about 394 mg/l in 2013. Effects of elevated CO2 concentration on uptake of plant nutrients such as nitrogen, iron, manganese, and zinc, on many agricultural crops have been studied. Improvement of nutritional conditions due to use of nitrogen fertilizers and increasing atmospheric CO2 concentration initiating increased photosynthesis and dry matter production results in promoting growth and yield increase of agronomic crops. At the same time this would change the concentration of necessary nutrients in the plants. This research is conducted with aim of studying effects of elevated CO2 concentration and nitrogen availability on plant nutrient uptake in wheat.
A greenhouse experiment in a factorial (combined) based on completely randomized design was conducted with soil texture in two levels (sandy clay loam and sandy loam), nitrogen in three levels (0, 100 and 200 mg/kg from urea source) in 4 replications of each treatment. Treatments were applied under two CO2 levels (ambient 400 and elevated 850 mg/l). A total of 24 pots in each CO2 level and 48 pots in total were used. Sixty days after planting, the aboveground parts were harvested and plant dry matter weight, nitrogen, phosphorus, potassium, iron, manganese and zinc in shoots were determined and compared.
results showed that with increasing CO2 concentration, in different nitrogen treatments shoot dry weight of wheat increased on the average by 10.67 percent. Increase in CO2 concentration did not have significant on shoot nitrogen and magnesium uptake of wheat but increased phosphorus, potassium, iron, manganese and zinc uptake by 18.58, 20.72, 32.87, 24.66, and 22.36 percent, respectively. Application of nitrogen fertilizer increased shoot uptake of nitrogen, phosphorus, potassium, magnesium, iron, manganese and zinc by 337, 93, 96, 145, 135, 129 and 156 percent, respectively, and this increase was more intense for phosphorus, potassium, iron and manganese in elevated CO2 concentration.
The amount of chemical fertilizers, especially nitrogen, and nutrient balance should be changed according to the weather conditions. Based on the results of this experiment, increasing soil nitrogen concentration resulted in an exacerbation of the positive effects of increasing CO2concentration. Therefore, if there is no limitation in the supply of essential nutrients, especially nitrogen, wheat growth and shoot uptake of most nutrients will increase under increased atmospheric CO2 concentration.