نشریه بوم شناسی کشاورزی
سال دوازدهم شماره 3 (پاییز 1399)

Introduction:

Durum wheat (Triticum turgidum L. var durum) consists of only 5% of the world’s total cultivated wheat area and contributes about 10% to the total global wheat production. In recent years, the production level of durum wheat has risen to more than 30 million tons and EU, USA and Canada together representing 60% of the production. Durum wheat in Iran is grown on 300-400 thousand hectares with an average annual production of 500-600 thousand tons. Increase in yield is one of the primary aims pursued in plant breeding programs. Similar to other crops, insufficient yield stability in durum wheat is recognized as a one of the factors responsible for the gap between actual yield and potential yield. In breeding programs, the identification of superior genotypes is difficult due to environmental variability of target locations and the interaction of these variability with the investigated genotypes. Therefore, it is important to evaluate the advanced agronomic lines across various environments and over multiple years to ensure their yield stability and production. Many statistical models have been suggested to analyze G×E interaction. The additive main effects and multiplicative Interaction (AMMI) model is a multivariate statistical method that entirely justifies genotype and environment main effects as well as multiplicative G×E interaction effects. This method provides a clear interpretation of G×E interaction effect. The objectives of this study were to analyze genotype by environment (GE) interactions on the seed yield of some durum wheat lines by AMMI model and to evaluate genotype (G), environment (E) and genotype× environment (GE) interactions using statistics parameter i.e. AMMI stability value (ASV) and ecovalence (W2i).

Sixteen promising durum wheat lines (G1-G16) along with two check cultivars (durum wheat cv. Hana and bread wheat cv. Parsi), were investigated for two cropping seasons (2015-2016 and 2016-2017) at three Agricultural Research Stations (such as Karaj, Kermanshah and Neishabour cities) The experimental design at all locations was a randomized complete block design with three replications. Some agronomic attributes such as the number of days until anthesis stages, plant height, number of days till physiological maturity, 1000-kernel weight and grain yield were determined for each genotype. However, only the grain yield data was used to analyze G×E interactions. Combined analysis of variance for grain yield was performed using ADEL-R software. The GGE Biplot methodology was employed to analyze G×E interaction. The AMMI M model was used for the following purposes; (i): Evaluation of yield stability, (ii): The simultaneous selection for yield and stability, (iii): Identification of ideal durum wheat genotypes, and (iv): Assessment of the characteristics of and relationships among the testing environments.

The combined analysis of variance showed that the main effects of year and location were significant at 1% probability level, while the main effect of genotype had not significant. Genotype× year interaction and triple genotype × year × location interaction were significant at 1% probability level and also genotype × location interaction was significant at 5% probability level, indicating genotype × environment interaction. The results of AMMI ANOVA showed that about 86.5% of total variation was related to environment effect, 1.4% to genotype effect and 12.1% to genotype× environment interaction. Overall, the average grain yield of the evaluated lines ranged from 7.6 to 8.4 t.ha-1 and the G18 and G2 lines had the lowest and highest grain yield, respectively. Main effect due to environment and genotype × environment interaction as well as two first interaction principal components (IPCA1-2) were found to be significant, indicating that the agroclimatic environmental conditions were different, and that there was a differential response of the genotypes to the environments. The first two IPCA components of the GE interaction explained about 70.2% of the GE interaction. According to IPCA1, G9, G15 and G16 had the lowest scores and were the most stable genotypes whereas G17 and G18 with the highest scores were found to be unstable. The lowest ASV was observed for G16 that was the most stable genotype whose mean yield was higher than the grand mean. However, the highest ASV scores were achieved by G17 and G18. AMMI Biplot was used to visualize mean seed yield performance and stability of durum wheat genotypes. AMMI Biplot was able to distinguish stable genotypes with broad sense and narrow sense adaptation and environments with high and low genotype discrimination ability. The genotype G16 with higher seed yield than the total mean were the most stable genotypes, while the genotypes G17 and G18 with the highest contribution to GE interaction were the most unstable genotypes. Wricke’s ecovalence stability parameter (W2i) showed that the genotypes G16, G12, G5 and G4 were the most stable genotypes.

The results indicated that AMMI model and their biplots was an appropriate method for simultaneous selection of performance and stability of cultivars and lines. Also, according to all of methods, genotype G16 was selected as a stable and high genotype across all environments. Finally, it can be considered as a favorite promising line compared to the check cultivar Hana and as a candidate in the temperate climate.

Medicinal plants are one of the main natural resources of Iran from ancient times. Coriander medicinal plant is one of the most valuable resources in the vast range of Iranian natural resources which, if properly managed, can play an important role in non-oil production and export. Management and environmental factors such as nutritional management has a significant impact on the quantity and quality of plants. Application of organic fertilizers in conventional farming systems is not common and most of the need for food plants supply through chemical fertilizers for short period. The use of bio-fertilizers and organic matter are taken into consideration to reduce the use of chemical fertilizers and increase the quality of most crops. The use of organic and biological fertilizers in the production of medicinal plants in a sustainable agricultural system is important in order to achieve product quality environmental protection and community health. Stability and soil fertility through the use of organic fertilizers are important due to having most of the elements required by plants and beneficial effects on physical, chemical, biological and soil fertility. Therefore, the purpose of this study was to evaluate the effects of different levels of amino acid and fulvic acid on vegetative, reproduction characteristics and yield of coriander.

In this study, the effects of applications of fulvic acid and amino acid on yield and growth characteristics of coriander were evaluated under field conditions. Treatments were two levels of amino acid (0 and 3 per thousand) and three levels of fulvic acid (0, 5 and 10 kg.ha-1). The experiment was designed as factorial arrangement based on randomized complete block design with three replications at the Research station of Faculty of Agriculture University of Birjand during growing season of 2017. The measured indices including vegetative characteristics (height plant, branches number, plant weight, leaf weight, leaf number) and reproductive characteristics (grain yield, 1000- seed weight, seed number, yield biological and harvest index). Finally, the experimental data were statistically analyzed using SAS ver. 9.2 and means were separated Duncan’s multiple test at 5% probability level of probability.

The results showed that fulvic acid had a significant effect on vegetative characteristics (height plant, fresh and dry weight of plant, branches number, leaf number and leaf dry weight), so that the highest fresh  and dry weight (49.9 and 7.3 g, respectively) were obtained  with application of 10 kg.ha-1 of fulvic acid. Also, the results showed a significant effect of fulvic acid on reproductive characteristics (seed yield, biological yield, harvest index and seed number), so that the highest seed yield (942.5 kg.ha-1) was obtained at 10 kg.ha-1 fulvic acid, and the lowest of seed yield was observed (710.0 kg.ha-1) in the control treatment. Amino acid also affected vegetative characteristics (leaf number and leaf weight), and reproductive characteristics (grain yield, seed number and 1000- seed weight), so that the highest number of leaf (27.0 per plant) and grain yield (873.3 kg.ha-1) were obtained with the application of 3 per thousand amino acids. Interaction effects showed that different levels of fulvic acid and amino acids had a significant effect on reproductive performance (grain yield, biological yield, seed number and 1000-seed weight). The highest grain yield and seed number (985.0 kg.ha-1 and 204.6. per plant, respectively) were obtained at 5 kg.ha-1 fulvic acid and 3 per thousand amino acid.

The results of this study showed that fulvic acid and amino acid had significant effect on yield and growth characteristics of coriander. Thus, results showed that fulvic acid (5 kg.ha-1) and amino acids (3 per thousand) had strong impact on yield and growth characteristics of coriander under field conditions.

Corn plant (Zea mays L.) is the main source of energy and has a vital role for birds feeding. Thus, increasing cultivation area and yield improvement are very important. Corn may be highly productive even in winter season in many locations due to its adaptability. Silage of maize is a good source of energy and food for animals and can produce more energy compare to other forages. Drought stress is one of the important factors that limits crop growth in arid and semi-arid environments and imposes a detrimental effect on maize yield. Drought stress imposes many different biochemical and physiological responses in plants. Studies have shown that water stress would directly and indirectly affect the maize yield.

This experiment was conducted as split plot based on complete block design with three replications, in 2017 (1396) in Mehran town in southwest of Ilam, which characters an arid and semi-arid climate. Main factor included of three levels of irrigation (equivalent of 40 mm (Normal), 60 mm and 80 mm of accumulated evapotranspiration of class A pan evaporation). Sub-plots included: 8 different levels of gibberellin application (100 ppm), no application of gibberellin but 4 levels of transpiration reducer including Salicyclic acid (0.5 molar concentration) ascorbic acid (120 mg.l-1), paclobutrazol (50 ppm) and control which was pure water. All treatments imposed at 6-8 leaf stage of plant growth. Each plot consisted of 6 cultivation rows with 4 m length and 0.75 m between rows and 0.20 m within rows distances. Distance between blocks was 3 m and sowing depth was 3-5 cm. Fertilizer requirement was calculated based on soil analysis. Therefore 160 kg.ha-1 of Super phosphate triple, and 100kg.ha-1 urea were applied at sowing and when crops were at 10 leaf stage, before tasseling, 200 kg.ha-1 urea was applied again. 

Irrigation levels showed a significant difference (P≤0.01) effect on grain yield, biological yield, harvest index, 1000-grain weight, grain number per ear, leaf area index, and relative leaf water content. ANOVA results showed that gibberellin had significant (P≤0.05) effect on biological yield. Transpiration reducer also showed significant (P≤0.05) effects on grain yield, biological yield, harvest index, 1000-grain weight, grain number per ear, leaf area index, and leaf water content. Interactive effects of drought stress and transpiration reducer was also significant (P≤0.01) on grain yield, biological yield, and harvest index. Triple interaction significantly (P≤0.01) affect grain yield and harvest index. The highest seed yield under normal irrigation conditions was obtained by simultaneous application of gibberellin and salicylic acid (11.11 t.ha-1). Also, the lowest seed yield was obtained under 80 mm irrigation stress without gibberellin and transpiration reducers (6.42 t.ha-1). Drought stress reduced grain yield compared to normal irrigation treatment. The lowest protein content was under normal irrigation conditions (0.092) and the highest amount was under 80 mm stress conditions (0.1). The highest accumulation of soluble sugars was in 80 mm dry stress (525 mg.g-1) and the lowest accumulation was in normal irrigation conditions (402 mg.g-1). The highest amount of chlorophyll (2.9) was observed in normal irrigation treatment and the lowest level was observed in drought stress treatment of 80 mm (2.46).

This study results showed that a right combination of transpiration reducer and growth stimulants under drought stress can help corn plant to increase its production. This enhancement is because of higher antioxidant activity and also growth conditions. In other words, positive effects of transpiration reducer, result in deduction of stress effects on grain production and biological yield so can increase corn quantity and quality grain yield.

Wheat (Triticum aestivum L.) known as a main crop in Iran. It is the main source of calories and protein which directly provides 37 percent of the food calories and 40 percent of daily protein for people in Iran. Breeding to produce new cultivars is always an important way to increase crops yield. New cultivars breeding is a very complex process because there is an interaction between climate and genotype and the time is limited to produce new cultivars adapted to new climates. The target trait identification can accelerate new cultivar breeding process. The objectives of this study were to explore the potential benefit of irrigated wheat traits over the country to increase the yield.

This study was performed at potential yield simulation using SSM-Wheat crop model to evaluate different traits impact on irrigated wheat potential yield in Iran. For this purpose, the protocol presented by Global Yield Gape Analysis (GYGA) was used to identify the same climate zones and the main weather stations for irrigated wheat in Iran. The potential yield of irrigated wheat was simulated by SSM-iCrop model for the area covered by each main weather stations. The average potential yield was calculated at the country level by scaling up the simulated results within the area covered by weather stations using the GYGA protocol. All the simulations and calculations were done for existing cultivars and for the cultivars with desired plant traits, identified in this study, under current and future climates. The effect of desired plant on potential yield was quantified by comparison of simulation results between existing cultivars and the cultivars with desired plan traits. Future climate (2055) scenario were created for the sites using the baseline 1986-2005 and the projections for delta mean air temperature (and precipitation) which is the difference between the future air temperature (and precipitation) and baseline air temperature (and precipitation). Deltas of air temperature and precipitation were obtained from the international panel on climate change report which it used 42 GCM model outputs under RCP4.5 climate change scenario to calculate them.

In this study, the effect of increasing and decreasing of biological days from tillering to stem elongation, biological days from anthesis to philological maturity, the rate of canopy development and radiation use efficiency on irrigated wheat potential yield were evaluated. Increasing biological days from anthesis to philological maturity increased the potential yield in all the regions under current (15.3 %) and future climates (16.8%). The potential yield gain from increasing radiation use efficiency was 14.7% under current climate and 13.7% under future climate. The effect of decreasing biological days from tillering to stem elongation, biological days from anthesis to philological maturity, the rate of canopy development and radiation use efficiency on the potential yield were negative. Monpara (2011) reported that increasing duration of grain filling period was an effective trait to increase wheat yield in India. Yang et al. (2008) demonstrated that the yield of rice increased with increasing cumulative radiation receiving during grain filling period. There was positive correlation between cumulative radiation receiving during grain filling and grain filling duration. With longer stay green duration, the potential yield of wheat increased thereby raising photosynthesis during wheat grain filling period (Spano et al., 2003).

Increasing radiation use efficiency positive effect on potential yield in the regions with warmer climate was higher than the region with lower average temperature over the year. Increasing radiation use efficiency had negative effect on potential yield in some cooler regions. Increasing biological days from tillering to stem elongation just had positive effect on potential yield in the region with warmer climate and its effect was negative in the regions with cool climate. The faster canopy development had no significant effect on potential yield.

The relation between agriculture and energy is very tight. Agriculture itself is an energy user and energy supplier in the form of bio-energy. Energy consumption in agriculture has intensified in response to increasing populations, limited supply of arable land and desire for an increasing standard of living. In all societies, these factors have encouraged an increase in energy inputs to maximize yields, minimize labor-intensive practices, or both. Effective use of energy is one of the conditions for sustainable agricultural production, since it provides financial savings, fossil resources preservation and air pollution reduction. In developing countries, agricultural growth is essential to fostering economic development. In Iranian economy, more than 33% of the total population is engaged in agriculture sector.  Recent years with the rise in world energy prices the governments has taken steps to reduce fuel and energy consumption. Energy in agricultural sector  are divided into two groups of direct and indirect, direct energy is required to perform various tasks related to crop production processes such as land preparation, irrigation, threshing, harvesting and transportation of outputs. Indirect energy consists of the energy used in the manufacture of fertilizers, seeds, herbicides and farm machinery and so on. Recently, application of integrated production methods are recently considered as a means to reduce production costs, to efficiently use human labor and other inputs and to protect the environment.

This research was carried out to evaluate the effect of conservation agriculture system on energy indices in conventional rotation systems including wheat, barley and cotton. The experiment was conducted at Gonabad Research Station as a moderate climate condition between 2012 and 2016 by using split plot design in a randomized complete block design (CBD) with three replications. Two substantial criteria were investigated such as different tillage methods including conventional plowing, reduction of tillage (Minimum tillage) and direct cultivation (No tillage) as a main plots, as well asamount crop residue involving absence of residues 30 and 60%of the remains as a subplots. The area for each subplot and main plot was 600 and 1800 m2, respectively. In this study, energy indices were calculated using equations .Besides, data analysis and mean comparisons were performed via SAS (SAS, 2002) software and Duncan test, respectively.

According to results, electricity, chemical fertilizers and fuel inputs shared the highest energy consumption from the total amount of energy in the conventional crop rotation with 43, 23 and 12%, respectively. On the other hand, the lowest energy consumption related to the input of human resources with an average of 0.7%. In addition, variance evaluation and statistical analysis of energy indices demonstrated that only energy efficiency index for wheat and barley at level (p≤0.05) dramatically affected by tillage methods. . However, the effect of residues and interaction between soil tillage × residues on other energy indices was not significant. Comparison of average values ​​of energy use efficiency index in the conventional rotation illustrated that the highest and lowest values ​​of this index were observed in two methods without soil tillage or direct planting and soil tillage or customary tillage. Therefore, the average of energy use efficiency index for wheat and barley crops in non-tillage method was represented increasing 21 and 9%, respectively, than that of conventional tillage and minimum tillage methods.

Consequently, based on data analysis, it seems that the implementation of conservation agricultural systems with various tillage procedures (non – tillage or minimum tillage) to enhane energy use efficiency is exclusively recommended for wheat and barley agronomic systems in climate condition of this study.

The explosion of world population in recent decades has caused excessive application of chemical fertilizers in agricultural systems; resulting in critical environmental and health issues. Integrated Nutrient Management (INM) method or biofertilizers are considered as logical strategies to reduce the rate of chemical fertilizers. . Biofertilizers consist of various types of microorganisms in soil which are in close relation with plant roots and are called Plant Growth Promoting Rhizobacteria (PGPR). Several mechanisms have been postulated to explain how PGPR benefit the host plant, which could be classified into four categories a) The ability to produce plant growth regulators or phytohormones such as indole acetic acid (IAA), cytokines, and gibberellins; b) Enhancing a symbiotic N2 fixation; c) Solubilizing inorganic phosphate and mineralization of organic phosphate and/or other nutrients; d) Antagonistic effect against phytopathogenic microorganisms by production of siderophores, the synthesis of antibiotics, enzymes, and/or fungicidal compounds, and competition with detrimental microorganisms. Therefore, PGPR are commonly used as inoculants for improving the growth and yield of agricultural crops, however screening for the selection of effective PGPR strains is very critical. This study focuses on the screening of effective PGPR strains on the basis of their potential for plant growth promoting activity under water stress conditions in Iran's cold temperate and warm dryland areas.

Experiments were carried out in randomized complete block design (RCBD) with four replications in 2009-2010 cropping year. Treatment included fifteen PGPRs with a control (without inoculation) in six dryland agricultural research stations; including Maragheh, Ghamloo (Kurdistan), Sararood (Kermanshah), Gachsaran, Khodabandeh (Zanjan), Shirvan Chardavol (Ilam). Soil samples collected from 0-25 cm depths before planting time and was characterized through determination of soil available P, K, Fe, Mn, Zn and Cu, soil texture, organic carbon, pH, EC and calcium carbonates equivalent. Dryland wheat Azar2 cultivar was cultivated with 350 seed per m2 in 5 to 7 cm soil depth. Moreover,plant traits such as grain, straw and biological yields, TKW (1000-kernel weight), number of spikes per m2, number of seed per spike, harvest index (HI), plant height and spike length, were measured. All research data was analyzed via GenStat14 statistical software.

The results showed that, the plant growth promoting bacteria (PGPR) had increased the grain yield of dryland wheat in the Maragheh, Kermanshah, Kurdistan, Ilam, Zanjan and Gachsaran regions. This increase in most experimental dryland stations has been significant statistically. The maximum grain yield increase in Maragheh, Kermanshah, Kurdistan, Ilam, Zanjan and Gachsaran were in the order amount of 19.6 (treatment no. 2), 45.1 (treatments no's 4 and 12), 12.4 (treatment no 8), 18.4 (treatment no 11) 10.2 (treatment no. 11) and 11.6 (treatment no. 11) kg.ha-1, which was 382 kg.ha-1 for the best average plant growth promoting bacteria in all the study regions. With the use of GGE biplot method, the inoculating treatments of plant growth promoting bacteria had 2 groups, including the high yielding groups with treatments (2, 3, 6, 8, 9 and 10), and low yielding treatments (1, 4, 5, 7, 11, 12. 13, 14, 15 and 16).The study locations were separated in 3 groups, first group including; Gachsaran and Kurdistan regions, second group including; Maragheh, zanjan and Ilam regions, and the third group including; Kermanshah region. The suitable treatments were the treatment numbers 9 and 10 for the first group, treatment numbers 2, 3, 8 and 6 for the second group and treatment numbers 7, 4 and 5 for the third group. Among the mentioned treatments, the most suitable treatments for first, second and third groups are treatment number 9, treatment number 2 and number 5, respectively.. According to these results, if the first aim is introducing the growth promoting bacteria for all the regions, this strain is the inoculating bacteria number 9. In the second order, the treatment numbers 13 and 10had the closest conditions to the estimated ideal treatment.

Therefore, for the plant growth promoting bacteria, we can use them in reducing the effects of environmental stresses, and conducting non-environmental stresses on dryland conditions, as well as increasing in grain yield of dryland wheat.

Climate change is one of the major challenges which society will face during current century. Temperatures are projected to increase up to 2 ºC by 2100, which is expected to result in major changes in the atmosphere’s energy balance and the hydrological cycle. The term soil moisture generally refers to temporary storage of precipitation at a depth of 1 to 2 meters from the soil profile). Soil moisture in the root zone well known as a very important factors that severely effects on crop productivity. Hence, the study of soil moisture changes is crucial for the planning and managing water resources in the coming periods. Accordingly, this study was conducted in order to predict and stimulate soil moisture in upcoming period (2020-2039) according to baseline (1992-2011).

The study area in this research was Neyshabour plain located in Khorasan Razavi province. At first, SWAP model implemented using meteorological and agronomic data from study area, and soil moisture of field capacity is simulated for 30 cm soil depth. Then, to ensure the results of moisture simulation, the moisture content of the model is calibrated and validated using the measured soil moisture content of the 2008-2009. After ensuring the accuracy of the model results, soil moisture is simulated for the baseline (1992-2011). Then, to estimate moisture content in the upcoming period (2020-2039) six models (CanESM2, GFDL, MIROC, IPSL, CSIROMK3.6, and GISS-ES-R) and two emotion scenarios (RCP4.5 and 8.5) were used, as well as the ratio of the weekly and yearly values of the meteorological parameters of the upcoming period, which estimated using the baseline. In addition, to evaluate SWAP model accuracy, Root Mean-Squared Error (RMSE), Mean Absolute Error (MAE), and Coefficient of Determination (R2) were used. Data obtained by Neyshabur Synoptic Station (1992-2011) were utilized in order to determine daily weather patterns and future weather parameters. Temperature and precipitation parameters determined by the LARS-WG model.

In order to use the SWAP simulated moisture, initially the model calibrated and validated with measured soil moisture data from 2008-2009 growth season. So, after soil moisture simulation for 2008-2009, the measured data by TDR used for calibration and validation model. The coefficient of determination factor (R2) between simulated and measured results was 79.5%. The climate parameters used in this study include minimum and maximum temperatures and precipitation, which are known as the most important factors affecting the soil moisture. According to table 6, the minimum and maximum temperatures and precipitation for the upcoming period will increase compared to the baseline. On the other hand, According to table 9 and table 10, under two scenarios, the means, maximum and minimum soil moisture decrease compared to baseline. The weekly and yearly uncertainty in soil moisture under two scenarios showed in figures 4 and 5, respectively. Under the 4.5 scenario, the MIROC model due to the lower band thickness and the IPSL model, due to the higher bandwidth thickness, have the highest and lowest accuracy, respectively. Whereas, under the 8.5 scenario, the IPSL model has the highest accuracy and the CanESM2 and GISS-ES-R models have the lowest accuracy compared to other models. Results of weekly and yearly uncertainty showed less and more uncertainty for weekly and yearly soil moisture, respectively.

In general, results of this study revealed that minimum, maximum temperature and precipitation will increase in upcoming period compared to baseline. Soil moisture decrease in upcoming period compared to baseline under two scenarios (4.5 and 8.5). Moreover, temperature was higher and precipitation was lower under 8.5 scenario rather than 4.5 scenario. Therefore, 8.5 scenario showed worse condition compared to 4.5 scenario. Results of this study showed lower soil moisture in 1, 3, 6, 13, 18, and 19 years in upcoming period under two scenarios. Therefore, these years known as warning condition compared to baseline.

Stochastical analysis can increase decision-making reliability, meanwhile increasing the flexibility of decisions. The critical role of climatic factors in land zoning on the one hand and the stochastical nature of climatic variables, on the other hand, causes the uncertainty of land suitability grading for plant cultivation, especially in dryland conditions. Golestan province has the third rank among the Iran provinces with about 400,000 hectares of cultivated land and production of more than one million tons of wheat, of which about 57 and 50 percent are allocated to rainfed cultivation, respectively. The present study was conducted to examine changes in various climate variables affecting wheat growth under the influence of different occurrence probabilities and zoning agricultural land in Golestan province for the rainfed wheat cultivation under these conditions.

 First, dates of planting and occurrence of each phenological stage of rainfed wheat were determined by daily data of precipitation and minimum and maximum temperatures for 33 weather stations in Golestan province in a 26-year typical statistical period. Then, by fitting different probability distribution functions and selecting the best distribution, the values of these variables were estimated at five occurrence probability levels of 25, 50, 75, 85, and 95 percent. Next, the average air temperature, the possibility of occurrence of adverse temperatures, precipitation and ratio of effective precipitation to potential evapotranspiration of wheat for each growth stage and total growth period were calculated for whole weather stations at different occurrence probability levels. Finally, by providing zoning maps of these variables and other features including elevation, land slope, land type, soil salinity and overlaying 22 layers for each occurrence probability level, agro-ecological zoning of agricultural lands of Golestan province for rainfed wheat cultivation at different occurrence probability levels was performed.

 Results showed that increasing occurrence probability level from 25 to 95 percent due to delaying suitable planting date from late autumn to early winter and its effect on the climatic-environmental conditions and the length of the plant growth stages improved the degree of land suitability grade for rainfed wheat cultivation in terms of mean air temperature in stages of flowering, maturity and total growth season, the occurrence possibility of temperatures higher than 14 and less than 9 °C in germination and flowering and maturity stages, respectively, and the amount of precipitation in the germination stage. Adversely, it resulted in degradation in the degree of land suitability in term of mean air temperature in the germination stage, the occurrence possibility of temperatures higher than 25 and 30 °C in flowering and maturity stages, respectively, and the amount of precipitation and ratio of effective precipitation to potential evapotranspiration in stages of flowering and maturity and the entire season. The results of agro-ecological zoning showed that the extent of suitable and moderate zones was between 50-56 and 44-50 percent of the agricultural land, respectively, for the occurrence probability levels of 50, 75 and 85 percent and the occurrence probability did not have a significant effect on zoning. In comparison, at the occurrence probability levels of 25 and 95 percent (equal to the early and late planting dates, respectively), about 91 and 78 percent of the province's agricultural land was located in a suitable and moderate zone, respectively. These results are accordant with the findings of Hoseini et al. (2018), who showed that the maximum extent of suitable land for cotton cultivation in Southern Khorasan province occurred in the early planting date. Considering the majority of agricultural land of Golestan province is located in the middle strip of the province, most changes of zoning maps by occurrence probability level have also occurred in this region.

A low reduction in cultivation risk (increasing the occurrence probability from 25 to 50 percent) significantly degraded the land suitability for rainfed wheat in Golestan province while more reduction in the farming risk (increasing the occurrence probability up to 85 percent) led to no significant effect on land suitability. However, if the minimum risk (95% probability) be selected as a management decision for rainfed wheat farming, the lowest land suitability for rainfed wheat cultivation will occur.

Summer savory (Satureja hortensis L.) is an annual medicinal herb, belonging to the family of Labiatae. This plant is native to the Mediterranean region and is cultivated extensively in France, Hungary, Spain, and Iran. Drought is one of the most important environmental factors responsible for decreasing global production and performance, especially in areas with low and irregular rainfall. Morphological indices such as plant height, stem length, yield, leaf area, and many of the growth traits of the plant are affected by drought stress.

A factorial layout based on a randomized complete block design with three replications was conducted at the Research Farm at the Mohaghegh Ardabili University, Iran, during 2016-2017. Treatments included three levels of drought stress (Full irrigation (s1), Water cut at 50% of flowering (s2), and Water cut in early stages of flowering (s3) and four vermicompost levels (including 0, 1, 1.5 and 2 t. ha-1). Plants were fully irrigated until eight weeks after seeding, and then drought stress was started at the early stage of flowering and 50 % flowering of plants. Fully irrigated plants throughout the growing season considered as control. The sampling was performed from cultivated plants, by the random collection of 3 individual samples. Samples to evaluate the morphophysiological, biochemical, and yield characteristics were taken at the full flowering stage. Traits such as plant height, dry stem weight, lateral branches, relative water content, electrolyte leakage, chlorophyll fluorescence, chlorophyll a, chlorophyll b, total chlorophyll, carotenoid, proline, protein, Catalase, and peroxidase antioxidant enzymes were measured and assessed. Data were analyzes using SAS V9.2. Mean comparison of results was made using Duncan's multiple range test at P≤0.05 levels.

Morphological traits: The results of the analysis of variance the effects of various vermicompost levels and drought stress and their interaction have been presented. The results showed that the effect of drought stress and vermicompost on plant height and shoot dry weight were significant at the 5% probability level. However, no significant effect was observed on the number of lateral branches. Also, the interaction of drought stress and vermicompost fertilizer treatments was substantial for plant height and dry weight of stem at a 5% probability level.The photosynthetic pigments: The results of the analysis of variance showed that the interaction of drought stress and vermicompost on chlorophyll fluorescence, chlorophyll a, chlorophyll b, and carotenoid was significant at 5% probability level, but the total chlorophyll has a considerable effect. The highest chlorophyll a (23.33 mg.kg-1), chlorophyll b (17.24 mg.g-1) and carotenoid (8.08 mg.g-1) in full irrigation treatment and two tons per hectare of vermicompost and minimum chlorophyll a (17.73 mg.kg-1), chlorophyll b (96.6 mg.g-1) and carotenoid (5.5 mg.g-1) in Water cut in early stages of flowering and Without the application of vermicompost (control).Proline: Based on the results of the analysis of variance, the effect of drought stress and vermicompost on the proline content of Satureja plant was significant at 5% probability level. The results showed that with increasing drought stress, the amount of proline in leaf was raised. However, with the use of vermicompost, leaf proline decreased, with the highest amount of proline (0.226 μg.g-1) in Water cut in early stages of flowering (severe stress) and without application of vermicompost (control) and low proline (0.15 μg.g-1) in Full irrigation (control) and vermicompost treatment (2 t.ha-1) were obtained. Investigating the drought stress on German chamomile plant, researchers reported that drought stress increased proline accumulation in the leaf (Ghaedi Jeshni et al., 2017). It was reported that increasing the amount of drought stress in sorghum increased the amount of proline in the leaf (Esmaeilpour et al., 2013).

Based on the results, it can be concluded that vermicompost 2 t. ha-1 can improve the medicinal plant growth and yield under severe drought irrigation regimes.
 

The nitrogen budget or balance is often evaluated by comparing various nitrogen inputs and outputs in soil–crop systems. Research on nitrogen balance can provide more detailed information on the nitrogen cycle and its losses by integrating soil nitrogen processes with the total nitrogen budgets. There are restricted researches for evaluation of nitrogen balances in the cropping systems. It is clear that accurate measuring of each component of nitrogen budgets in relation to soil processes is difficult. Wheat (Triticum aestivum L.) is the main cereal crop cultivated in Iran. According to published data the average nitrogen application rates in wheat cropping systems of Iran is 120 kg.ha-1 but, the excessive use of fertilizer nitrogen is very common in wheat fields. It is estimated that in Iran, about 2.2 million ha of wheat production areas are under irrigation. Alike, there are limited studies on nitrogen dynamics, budgets and its losses pathways in wheat production systems of Iran. Such studies are essential to understand the nitrogen behavior and balance in wheat cropping systems. This research was carried out with the aim of evaluating nitrogen balance of wheat cropping systems with different climatic conditions over the country by using CENTURY model.

We used CENTURY model (Parton et al., 1994) to evaluate nitrogen dynamics and nitrogen balance in wheat cropping systems. For this purpose 14 wheat cropping system located in diverse climates were selected. Soil data was collected from Soil and Water Research Institute and weather data from 2000 to 2014 were obtained from Iran Meteorological Organization for 14 selected stations. The CENTURY model simulates the long-term dynamics of Carbon (C) and Nitrogen (N), for different Plant-Soil Systems. The model can simulate the dynamics of agricultural crop systems. The crop system of CENTURY have different plant production sub-models which are linked to a common soil organic matter sub-model .The soil organic matter sub-model simulates the flow of C, N through plant litter and the different inorganic and organic pools in the soil. CENTURY model runs in monthly time step with monthly precipitation (cm), monthly mean minimum and maximum temperature (°C), site latitude and longitude, sand, silt and clay (%), soil bulk density (g.cm-3), rooting depth (cm), C and N content of the top 20 cm of soil and management information such as planting date, first and last month of wheat growth, number and amounts of applied fertilizers, amount of irrigation water and its schedules are required. For model validation we used two statistical measures including Normalized Root Mean Squared Error (nRMSE), Willmott (1982) index of agreement (d value) and linear regression coefficients between actual and predicted values.

Results revealed that the highest nitrogen input in wheat cropping systems (9.5 - 12.5 g.m-2) was observed in Northwest, West and Southwest and the lowest (7.3 - 9.4 g.m-2) were in East and Southeast areas of the country. Also, nitrogen output plan in wheat cropping systems was similar to nitrogen input. In addition, stepwise regression analysis indicated that fertilizer application rate with partial coefficient of 97.33% and grain nitrogen with partial coefficient of 92.79%, respectively, were the most important variables in relation to nitrogen input and output in wheat cropping systems of Iran.

According to the results, it seems that in relation to nitrogen input, the role of agronomic management such as fertilizer application, coincidence of fertilizer application time with plant requirement and increasing nitrogen use efficiency (NUE) which is mostly dependent on agricultural management are important issues. But in the case of nitrogen outputs from wheat cropping systems, in addition to agronomic managements, use of improved cultivars with higher nitrogen uptake efficiency is more important.

Introduction:

Climate change and global warming are the most important challenges in sustainable development, which is due to increased concentration of greenhouse gases in the atmosphere. Carbon dioxide is a major component of greenhouse gases. In order to reduce atmospheric carbon dioxide and to create a balance in the content of greenhouse gases, atmospheric carbon must be absorbed in organic forms (Dieleman et al., 2015; Lichtfouse, 2009). For this aim, a study was done in agricultural lands of Gorgan in order to estimate the carbon sequestration potential of soybean plant (Glycine max L.).

This research was carried out in 150 soybean fields of Gorgan township and sampled by quadrate 0.5Í0.5 m2 as random method, during 2016-2017. The soybean shoot and root organs were individually harvested and transferred to the laboratory. An electric burn furnace method was used to determine the carbon sequestration potential in soybean organs (including pods, seeds, stems, leaves and roots). Also, the amount of shoot to root and harvest index were estimated to determine the net primary production based on carbon content in the above ground organ, below ground organ and total plant, and the carbon allocation coefficients in each soybean organ. Then, using different interpolation methods, the spatial distribution of carbon sequestration of the plant organs was investigated in ArcGIS software. All data were analyzed by SPSS software.

The results showed that Kriging method was the best model for carbon interpolation and distribution of carbon sequestration potential in agricultural lands of Gorgan township. The amount of stored carbon was obtained as 579.64 kg.ha-1 in leaves, 744.81 kg.ha-1 in stem, 881.16 kg.ha-1 in seeds, 340.16 kg.ha-1 in pods and 540.21 kg.ha-1 in root. Also, according to harvest index (32%) and grain yield (3461.13 kg.ha-1), other indexes were calculates as the ratio of shoot to root about 4.30, the total net primary carbon production 6734.8 kg.ha-1, above-ground net primary carbon production 4867.2 kg.ha-1 and below-ground net primary carbon production about 1867.63 kg.ha-1. Also, the shares of the allocation coefficients of economic organs, stems, leaves, root and root secretions were 0.23, 0.49, 0.61 and 0.12, respectively. The zoning results showed that the total stored carbon potential in soybean plant was highest in the eastern, north and southeastern regions of the surveyed area, and the central, western and southwestern parts of this township had the lowest stored carbon potential. Also, the amount of carbon sequestration potential (total above ground and below ground organs) was as 3085.98 kg.ha-1 in this study.

 The highest proportion of carbon was allocated to the shoot organs, and the carbon of root exudates was also lower than other plant organs. In this study, it has been found that the potential of carbon sequestration was different in soybean plant organs and some variable such as agronomical management, soil and climatic condition can affect on its contents.AcknowledgementsWe are thankful to Gorgan University of Agricultural Sciences and Natural Resources (GUASNR), Agriculture Services Centers of Gorgan and soybean farmers for all their companions and supports.