فهرست مطالب benjamin torabi

The present study was conducted in order to estimate the yield gap of faba bean in the main production areas of this plant in Golestan province, including Gorgan, Ali Abadkatol and Aq Qola cities, and to identify the factors that cause it and to determine the contribution of each of them.

Based on this, the information related to the production management of 445 faba bean farms in Gorgan, Aliabadkatol and Aqqola regions in 1398-1399 and 1399-1400 was collected and the yield gap was estimated using the comparative performance analysis (CPA) method.

 The average, maximum, and gap yield of faba bean seeds were 2742, 4000, and 1258 kg per hectare, respectively. Additionally, based on the results obtained, the most important reasons for the yield gap and the contribution of each of them in creating the yield gap were: planting date 21%, pests 15 percent, the amount of pure nitrogen (N) 14 percent, the number of disc times 14 percent, the amount of seed used 12 percent, diseases 12 percent, waterlogging 5 percent, weeds 3 percent, non-use of working row 2 percent and improper planting depth 1 percent.

In general, by optimizing the management of faba bean production and eliminating the mentioned factors of yield gap, it is possible to increase the yield of faba bean in the regions of Gorgan, Ali Abadkatol and Aq Qala of Golestan province by 46 percent (equal to 1258 kg per hectare) compared to the current amount increased.

Water stress affects the crucial processes and yield of crops. This study aimed to investigate the effect of water stress on physiological and biochemical traits of safflower genotypes.

A factorial experiment was carried out as randomized complete block design in Seed and Plant Improvement Research Institute during 2017-19. The treatments included two irrigation levels (40 and 80% depletion of available water) and Parnian, Goldasht and Kazak genotypes. Plants were sown in soil columns with a height of 150 and a diameter of 23 cm, and irrigated by a drip system. Antioxidant enzymes, malondialdehyde, proline, relative water content, chlorophyll, seed yield and fatty acid composition were measured at the end.

Water stress significantly increased the accumulation of hydrogen peroxide and malondialdehyde in safflower genotypes which led to increased catalase and peroxidase enzyme activity by 1 and 2.5 U, respectively. The proline content increased about 16 times under water stress conditions. In contrast, the relative water content showed a significant decrease, which resulted in increased canopy temperature and decreased seed yield by 70%. The Kazak genotype had the lowest increase in canopy temperature under stress conditions and showed higher yield stability. Moreover, the fatty acid composition of seed oil changed and the amount of linoleic acid decreased by 1.8% under water stress conditions.

The results showed that in addition to drought-related physiological traits, no increase in saturated/unsaturated fatty acid ratio is also an important indicator in screening superior genotypes for cultivation in water shortage.

With regard to the ever-growing water deficit in the world, the adoption of the direct-seeded rice cultivation system has been suggested as an alternative to the transplanting method. One of the disadvantages of the direct-seeded method is low and non-uniform germination and emergence due to low seed vigor in rice. Priming is a technique which improves the rate and uniformity of seed germination under these conditions. Thus, this study aimed to investigate the effects of priming treatments on seed germination of different rice cultivars under different temperature conditions using the thermal time model.

This study was conducted in 2019 at the seed research laboratory of Gorgan University of Agricultural Sciences and Natural Resources. In this experiment, germination of primed and non-primed seeds in three rice cultivars (Nada, Anam, and Tolo) was investigated under different temperatures (15, 20, 25, 30, and 35°C). The priming treatments which consisted of control, hydropriming, and osmopriming with different chemicals (potassium chloride 2%, potassium nitrate 1%, calcium chloride 4%, glycine betaine 10 ppm, salicylic acid 10 ppm, and ascorbic acid 10 ppm) were investigated under different temperatures.

The results showed that priming treatments had no significant effect on the seed germination percentage of rice cultivars at different temperatures. The thermal time model based on binomial distribution fitted well to cumulative germination percentages in all priming treatments. Among the parameters of the thermal time model, the greatest priming effect was on the reduction of the thermal coefficient, followed by the reduction of the sigma coefficient, which resulted in the increased rate and uniformity of germination. Priming treatments had no significant effect on base temperature. Also, the responses of rice cultivars to seed priming treatments varied so that in Anam and Neda, priming with calcium chloride but in Tolo, hydropriming was more effective on the model parameters, especially thermal time to 50% of germination.

In general, priming treatments did not affect the base temperature of germination in rice cultivars, but they significantly affected the rate and uniformity of seed germination. As the latter issue is one of the main problems in the direct-seeded rice system, suitable priming treatments for each cultivar can be adopted to increase the rate and uniformity of seed germination and emergence in this system.

Pollen flow in anemophilous plants is a dynamic process. This controlled by wind speed, turbulence direction and depends on, plantation map, rate of air humidity, male genotype and female cultivar biological characteristics. The aims of this research were to survey and analysis pollen dispersal model in distance from few male genotypes within a block of Shahpasand and Akbari pistachio cultivars.

The lams coated with thin layer of Vaseline gel were installed on piece of wood tied on top of wooden bars. The bars had a distance of 7 m to each other as distance of female trees. . The lams were installed horizontally and vertically on bars which had planted beside female tress from a distance of 8 to 64m in Shahpasand and 80 m in Akbari plot. Every lam was installed on woody bar from 8 am to 8 am of next day and number of pollen was counted on horizontal and vertical lam via a light microscope. Data were analyzed using RCD and regression analysis, as Y is accounted as pollen intensity and X as distance to pollinizer.

Results indicated the pollen intensity was declined after 35 m distance from male genotypes. Further, fruit set also indicated a decreasing trend as distance had been increased from male genotypes. However, the intensity of pollen was differed on different day. This was due to some differences appeared by wind speed and direction. The best wind speed on 2 M height from the ground was 10 km/h equal to 2.7 m/s. On days when the speed of winds was raised to more than 30 km there were no traces of pollens dispersal on lams and dusts were replaced. The maximum intensity of pollen in Akbari plot was found in distance between 20 to 30 m from male trees. The recent results indicated a sinusoidal model. There was no found significant differences in fruit set percentage by open pollination and by controlled pollination by hand in Shahpasnand plot. Even though the intensity of pollen was reduced in 40 m distance from male tree but this condition had no effect on rate of fruit set percentage in Shahpasand plot.

Within this research it was cleared that pollen intensity in both plots of Shahpasand and Akbari female trees was influenced by wind speed, wind direction and frequency of male trees. Intensity of pollen was reduced by 40 m from pollen source in both plots of Shahpasanand and Akbari. There was no reduction in fruit set at Shahpasand by 60 m distance from the male tree. It is suggested plantation of few male tree in the row for 3 of 4 rows of female pistachio trees would be more beneficial for orchardist

The process of producing agricultural products has a certain complexity and finesse and is affected by various factors. These factors, in turn, pose numerous challenges in the field of global agricultural production. Therefore, in order to reduce these problems and improve the activities resulting from production, in the first place, it must pay attention to how management operations. This requires monitoring all stages leading to production through documentation. Documenting the production flow (collect all the steps and operations of the production line from preparing the seedbed to harvest) is one of the first effective steps in improving management processes in agriculture. The aim of this study was to investigate the details of the production process and all agronomic operations and in order to reduce the challenges related to farm management and ultimately improve the yield of rice in the Ghaemshahr region.

Due to the importance of documenting the production process, in this study there were three groups of information related to agronomic management, soil and crop during the crop years 2019 and 2020 in the field and with continuous monitoring of the studied farms during the growing season and during the stages of planting, holding and harvesting were recorded and collected. In these studies, it was determined the range of changes and the manner of performing each management operation and the proportion of farmers who used different management methods, with absolute and cumulative frequency distribution.

The results of this project showed that the date of transplanting in the region is between 29 April to 9 June. Transplantation is often traditional (by labor). The amount of seed used varies between 30 to 144 kg.ha-1 depending on the type and quality of seed, type of nursery and transplanting method, soil texture, local and experimental knowledge of the farmer. About 54% of farms still use self-consuming seeds. Despite the variety of figures, Tarom Hashemi is more welcomed. Urea, triple superphosphate and potassium sulfate are the dominant fertilizers to meet the nutritional needs of the rice plant. Most of the installments are allocated to urea fertilizer. Depending on the weather conditions and the type of cultivar, harvesting is usually done between July 19 and September 20 and 95% with rice combine. Due to the variety of cultivars and management methods, the yield of paddy varied between 2269 to 11052 kg.ha-1.

By documenting the production process while being aware of the current situation of farms in the region, it is possible to solve the existing problems in production systems and reach the ideal situation. Also, in doing similar projects, rework and spending a lot of time and interruptions in work are avoided.

overcoming the growing human need for food, which is in line with population growth, is a global challenge. Therefore, this study has evaluated the potential performance and yield gap and identified the limiting factors of production using the border line analysis method.

In order to quantify the production and estimate the rice yield gap in Ghaemshahr region, the data collected from 164 paddy fields (local and high yielding cultivars) of this city were used. Information on important managerial, soil and plant factors were recorded during the growing season through continuous field visits and face-to-face interviews with farmers. In this study, using the boundary line analysis method, the yield gap, potential performance and optimal values of yield gap parameters were calculated and the best managements were determined simultaneously.

In the present study, the quadratic function was able to describe the trend of performance changes in relation to different traits. The required optimal minimum values of each factor were determined to achieve the highest performance. The average optimal yield (achievable) and the average actual yield were 9229 and 5160 kg.ha-1, respectively, and the yield gap was 4069 kg.ha-1, equivalent to 43.8% of the potential yield.

The border line analysis method was able to successfully estimate ways to increase production while reducing the yield gap in the region, significantly help. It is recommended that boundary line analysis be used as a functional analysis alongside other methods, for different crops and in other areas.

Crop simulation models are very useful tools for the evaluation of plant growth and development processes. Crop-simulating models may be used to estimate yield and evaluate climatic, plant, and management parameters on yield. Also, it may be used to predict crop water requirements under different conditions. Crop models should be evaluated and parameterized to simulate crop growth and development. Parameterization is used for precise simulation of crop growth and development and can estimate the best and most appropriate values for model parameters obtained via observed data or calibration. The objectives of this study were to describe the SSM-iCrop2 model, determine plant parameters, and evaluate alfalfa (Medicago sativa L.) in its major production regions using the SSM-iCrop2 model in Iran.

SSM-iCrop2 crop simulation model is a simplified form of SSM crop models which is suitable for the simulation of growth, development, and yield of different crops under different environmental conditions and large-scale estimation of crop production, especially in the evaluation of nutrient availability and climatic effects. This model includes sub-models of phenology, leaf expansion and senescence, dry matter production and distribution, and soil water balance. Daily weather data, agronomic management, soil properties, and plant parameters are required for simulation in this model. The present study investigates the performance of the SSM-iCrop2 model regarding the prediction of single cuts and overall cuts, phonologic stages, and water requirement of alfalfa under changing climatic conditions in Iran. To simulate the growth, development and yield of alfalfa using SSM-iCrop2 model in Iran, the major irrigated alfalfa production provinces, including East Azarbaijan, Hamedan, West Azarbaijan, Sistan and Baluchestan, Khorasan Razavi, Esfahan, Kordestan, Ghazvin, Ardabil, Markazi, Fars, Zanjan, Chaharmahal and Bakhtiyari and Tehran were identified based on the data available in Ministry of Agriculture statistics. Then, field experiment data required for model parameterization and estimation were collected from these provinces.

According to the results of the SSM-iCrop2 model parameterization, two cultivars with different leaf area indices (high-yielding and low-yielding) were identified in major alfalfa production provinces. The model was evaluated using independent experimental data that had not been used for parameterization. The evaluation results for alfalfa yield showed that the observed single-cut forage yield ranged from 112 to 640 g.m-2 with an average of 330 g.m-2; the observed total annual forage yield ranged from 646 to 4042 g.m-2 with an average of 1717 g.m-2; and the water requirement of alfalfa obtained from the NETWAT software was between 5140 to 12690 m3 ha-1 with an average of 8746 m3 ha-1. The predicted single-cut forage yield, predicted total annual forage yield, and alfalfa water requirement ranged from 189 to 457 g.m-2 with an average of 351 g.m-2, 693 to 3296 g.m-2 with an average of 1654 g.m-2, and 4093 to 16874 m3 ha-1 with an average of 10940 m3.ha-1, respectively. Overall, in the evaluation of observed versus simulated alfalfa forage yield, 31 points were obtained for single-cut yield with a correlation coefficient (r) of 0.79, root mean square error (RMSE) of 88.3 g.m-2, and coefficient of variation (CV) of 26.78%; and 21 points were obtained for annual yield with an r of 0.90, RMSE of 344.4 g.m-2, and CV of 20.05%. The evaluation results also showed that the observed versus simulated alfalfa water requirement had an r of 0.43, RMSE of 3503 m3 ha-1, and CV of 40%.

The results obtained from parameterization and evaluation of the SSM-iCrop2 model show that the mentioned model presents a logical prediction and accurate estimation of model parameters for yield and water requirement of alfalfa crops in Iran. Thus, this model may be used for the prediction of alfalfa yield under different climates and management conditions.

It is necessary to evaluation of the occurrence of climate change, Inadequate distribution and Stop of rainfall in the final stages of wheat growth in Varamin.

From the output of HadGEM under RCP4.5 and RCP8.5, to simulate the future climate using AgMIP model with long-term baseline data (1980-2009), in the periods of 2025, 2055 and 2085 were used. SSM model was used to simulate the phonological stages of wheat and in order to calibrate and validate the model, an experiment in the form of a randomized complete block design with five treatments including; [No stress, booting stage, Flowering, Milking, and Doughing], with 3 replications, was carried out during the 2020-2019 growth season in Varamin.

The SSM model simulated the occurrence of phonological stages with high accuracy. In 2085 period under RCP8.5, the highest increase of Tmax and Tmin was observed with 6.9 °C and 5.6 °C compared to the baseline period, respectively. While the amount of precipitation decreased in 2025 and 2055 under RCP8.5, but it increased in RCP4.5. The smallest difference between day to Flowering, BSG, TSG and day to was related to the period 2025 under RCP4.5 with 3, 9, 12 and 11 days, respectively. The highest differences were observed in the period 2085 under the RCP8.5 with 90, 77, 47 and 43 days, respectively.

Increasing the temperature and decreasing rainfall have neutralized the beneficial effects of increasing CO2 concentration and these factors have shortened the duration of phonological stages.

Rice is one of the most important cereals and staple food of many people in the world. In order to identify the possibility of supplying food to the world's population, given the need for continued production in sustainable agriculture, it is necessary to correctly predict the yield of crops. For this purpose, modeling of growth stages and yield of rice based on meteorological statistics of Iran, was studied in Gorgan University of Agricultural Sciences and Natural Resources. The purpose of this study was to use the simple model SSM-iCrop2 to simulate rice growth and yield to investigate the effects of climatic factors, soil, agronomic management and to determine the genetic coefficients of rice in Iran. Due to the appropriate ability of the model in rice simulation, it can be used as a suitable tool for better planning and management of rice fields in the country. In this study, the SSM-iCrop2 model was used to simulate the potential yield. In this model, the amount of potential yield is calculated based on meteorological data, soil conditions, management and plant parameters. The model needs a series of inputs to run, which is made to perform the simulation of the collected model. The most important processes to be simulated in the model are plant phenology, leaf area changes, dry matter production and distribution, and soil water balance. For parameterization and evaluation of the model, the values of performance and day to maturity of the simulated were compared with those observed. For this purpose, a set of experimental data (data related to rice growth and production from published and unpublished articles and reports) was used in important areas under rice cultivation. According to the statistics of the Ministry of Agriculture, 2001-2016, the main areas of rice cultivation and production in Iran were identified. In this study, to compare the deviation of the simulated values from the observed squared error mean (RMSE), coefficient of variation (CV), correlation coefficient (r) and the deviation of the simulated results from line 1:1 with a range of 20% difference. Between the simulated and observed values was used to test the model results. In parameterization of SSM-iCrop2 model for rice, the comparison of observed and simulated days to maturity with RMSE, CV and r values of respectively 12 days, 11 percent and 0.61, respectively, and for grain yield of 56 g m-2, 21 percent and 0.80 indicated the accuracy of the used parameters. Furthermore, in evaluation the model, RMSE, CV and r values for days to maturity were 9 days, 10 percent and 0.95 and for grain yield were 43 g m-2, 14 percent and 0.77 and in simulation evapotranspiration were 44 mm, 9 percent and 0.79 respectively, which confirms the precision of the model simulation. Application of SSM-iCrop2 model is simple and acceptably precise simulation is possible with minimal parameters and inputs. The results of parameterization and evaluation of SSM-iCrop2 model, which was (RMSE), (r) and (CV), showed that this model includes phenological stages and grain yield in the history of different plantings in the climatic conditions of Iran simulates with great accuracy, which indicates the appropriate structure of the model in the simulation. Therefore, considering the appropriate accuracy of SSM-iCrop2 model in simulating rice phenology and yield, it can be used as a suitable tool to study cropping systems and interpret the results in different environmental and management conditions to plan and improve the management of rice fields in the country.

In order to investigate the variation in germination rate, cardinal temperature and hydrothermal time parameters of wild mustard seed in different water potentials were designed and implemented during the study in gorgan university of agricultural sciences and natural resources, in 2017 as a split plot done in a completely randomized design with three replications of the municipality. In this research, germination modeling was performed well. To describe the germination rate response to temperature in different potentials of water 0, -0.2, -0.4, -0.6, -0.8 MPa were used from the dent-like function. By applying different concentrations of gibberellic acid (100, 300, 500, 1000, 1500 and 2000 ppm), the process of germination changes in the studied temperatures was incremental, so that the highest germination percentage was related to gibberellic acid 2000 ppm. By reducing the potential at each level of gibberellic acid, the base temperature increased and the lower and upper optimum temperature and the ceiling temperature decreased. The hydrotime coefficient in control seeds decreased significantly with increasing temperature and the water potential was increased. The hydrotime coefficient and base water potential increased with decreasing gibberellic acid. The results showed that the coefficients obtained by the hydrothermal time model were of relatively high precision and the constant value of hydrothermal time, base water potential and base temperature in control seeds were 1173.83 MPa ºC h-1, -0.09 MPa and 3.07 °C and for gibberellic acid with concentration of 2000 ppm were 315.57 MPa ºC h-1, -0.50 MPa and -1.22 ºC, respectively. Changes in the base water potential for 50% of germination in gibberellic acid 1500 and 2000 ppm treatments had a two segmented trend up to 20 °C so that it -0.7 to -0.6 MPa and increased above 20 °C the maximum value at 30 °C.

Saffron (Crocus sativus L.) is a perennial plant and geophyte, triploid and belongs to the family of Iridaceae. One of the most important factors that has a great effect on the final performance is the size of corm. Therefore, in order to obtain large corms, it is very important to create suitable environmental and management conditions. Determining the appropriate planting depth is also one of the ways to improve the performance of saffron per unit area. The purpose of this research is to investigate different sizes of saffron corms and planting depth on the yield of daughter corms of different sizes, flower and dry stigma of saffron in the conditions of Sari plain.  The present study was conducted to investigate the effect of different weights of mother corms and different planting depths on corm production and saffron yield in a factorial experiment based on a randomized complete block design and in three replications in the research farm of Sari Agricultural Sciences and Natural Resources University during the growing season 2019-2020. The experimental treatments included three corm sizes: weight group; small 4±2 g, medium 10±2 g and large 15±2 g and two planting depths of 10 and 15 cm. The studied traits included: the number and yield of daughter corms, the number of buds, the number and yield of flowers and the yield of dry saffron stigma. Data analysis and graphs were done using SAS 9.0, Excel 2016 and Sigma Plot 12.0 software, respectively, and comparison of average data with the help of LSD test at 5% probability level.  The trend of temperature changes as well as the investigation of the phenological events of saffron in the study area showed that at the beginning of the growing season and in the middle of autumn, the emergence of leaves is observed along with the emergence of reproductive organs (fig.1); This factor is probably related to the temperature fluctuations at the beginning of the plant's growing season (Table 1), and on the other hand, due to the allocation of the stock of mother corms to the leaves, it ultimately reduces flowering and stigma yield. The results showed that the highest number of daughter tubers and the total yield of daughter corms with 485 corm/ m2 and 2435.3 g/m2, respectively, were related to the treatment of large mother corm; however, no significant difference was observed between these traits in two planting depths for large corm (Table 2). The lowest total yield of daughter corms related to the treatment of planting small mother corms at a depth of 10 cm was equal to 1488.7 corm/ m-2. The average weight of daughter corms produced in this experiment (between 4.72 and 5.37 g) was about twice more than the amount produced in dry areas (Moallem Banhangi et al. 2019, Moein Rad et al., 2018. Razavian et al. 2019, Sharifi et al. 2021 & Esmi et al. 2019).  According to the results obtained in this experiment and also taking into account the texture of the field soil under test, the depth of 15 cm is more suitable than the depth of 10 cm for the production of corm with the desired size. But there is a possibility that in areas and lands with heavier soil, especially in the conditions of Mazandaran plain, which has abundant rainfall and poor drainage in some areas, shallower planting (10 cm deep) is better than deeper planting. It created more favorable conditions for root growth. Because the shallow planting depth, while creating drainage and better exit of excess water from the environment around the root and stem, provides a better growing environment for the growth of this plant. Therefore, according to the mentioned cases and the climatic features of the Sari plain, for better productivity of agricultural land in autumn and winter, saffron cultivation should be done annually and with priority to produce high-quality seeds and use these seeds in saffron-rich areas or conditions Aviation can be considered.

Saffron can be cultivated in many regions of the world with different climates. But the best climate for growing saffron is the Mediterranean climate with its warm and dry summers. The present study was conducted to evaluate some indicators of saffron growth in 2019-2020 in four region with different altitudes above sea level in Sari, Iran. These regions include Sari plain (level with sea level), Sarkat (350 meters above sea level), Reskat (900 meters above sea level) and Margav (1350 meters above sea level). These experiments were performed in a randomized complete block design with three replications. The treatment was includes corm size in three weight groups: small (4±2 g), medium (10±2 g) and large (15±2 g) and Measured traits include leaf area index, cumulative dry matter, growth rate, relative growth rate and saffron yield. The results showed that the trend of saffron leaf area development in all studied regions has a non-linear trend and follows a logistic-peak function. Based on the results, a significant difference was observed between the leaf area development trend among different sizes of mother corm in all regions and the trend of leaf area index changes during the growing season was higher for larger corms than for smaller corms. The trend of changes in dry matter accumulation also had a sigmoidal trend in all experiment region. Total dry matter changes were higher for larger corms. Although the trend of changes in crop growth rate in higher altitude region was lower; But the rate of growth rate fluctuation or in other words the difference between the minimum and maximum growth rate during the season in the two higher regions was less than the lower regions. The growth trend of saffron in four regions showed that it grows during the season in region with higher altitudes above sea level and following more vegetative growth and more dry matter allocation to the storage organ, larger corm is produced and the potential to increase the yield of dried saffron flowers and stigmas will increase next year.

All over the world, there are high salinity lands and most of those considered as an arid or useless lands (from agriculture aspect) for lack of knowledge about resistant varieties. Quinoa plant indicate significant resistance to wide range of Abiotic stress such as salinity and cold. Also this plant is protein-rich and can be a good alternative to rice and wheat. It is necessary to study about this kind of plants in the critical condition (saline soil & dry farming) more than ever. In this paper we investigate about the impact of date of planting and density in dry farming and saline soil on quinoa plant yield.

In this study, the experiment, split plot design in completely randomized block base format with three repetition in the crop year 2019 (1397- 98) was performed in one of the farms of Gomishan city, Golestan province. Main factor consists of three planting date (February 4, March 6, April 4) and subsidiary factor has three density (60, 80, 100 and 120 plants per m^2). To determine the length of growth stages and dry weight and doing analysis, Sampling was done once in every two weeks. Final yield is determined by split middle line. during the growth season the important dates of plant phenology such as time for emergence & seedling development, physiological maturity, flowering and grain development divided by different treatment notes were taken. lastly, data obtained were analyzed by statistical software SAS and average data evaluated by LSD test.

The results indicate significant impact of planting date on plant height, number of seeds per panicle, dry weight of the plant and weight of one thousand seeds significance 1 percent level and weight of panicle, number of seeds of branch were at significance 5 percent level. Maximum values of this functional traits was obtained in planting date february 4. and planting date March 6 has the lowest values of these traits. plant height, number of seeds per panicle, wet and dry weight of the plant significantly affected by density factor. all interactions of both factor had huge impact on measured traits. most yields in 60 and 80 density plants per m^2 were significantly more than this trait's value in other planting density. results of this study indicate that february 4 was the best quinoa planting date (in comparison to other reviewed planting dates) for Gomishan and its condition, also 80 density plants per m^2 (high density without any decreased yield) is the most suitable for there.

Due to the quinoa high resistance to drought and salt stress as well as appropriate performance, as a strategic product could be recommended to farmers. by the results of this paper we can conclude that february 4 is the best planting date for saline soil and dry farming. delay to cultivation has a significant decrease in reviewed traits. moreover, because 80 density plants per m^2 increased the plant yield in most traits, then it could be considered as a most appropriate density to this study condition. however to confirm this findings it is necessary to check this experiment another year.

Common morning-glory (Ipomoea purpurea L.) is one of the most important harmful weeds in summer crops in Golestan province. Germination is one of the most important stages of plant life and the study of environmental factors affecting the germination of weeds is necessary for their proper management.

In order to investigate the effect of some environmental and management factors on seed germination and emergence of common morning-glory, experiments were conducted in the laboratovar and research greenhouses of the Gorgan University of Agricultural Sciences and Natural Resources in 2017. In this study, common morning-glory response to constant temperature (5, 10, 15, 20, 25, 30, 35, 40 and 45 ° C), alternating temperature (5:15, 10:20, 15:25, 20:30) , 25:35), high temperature (temperatures of 50, 80 and 100 ° C for 5 and 10 minutes), drought (0, -0.2, -0.4, -0.6, -0.8, -1 MPa), salinity (0, -0.2, -0.4, -0.6, -0.8, -1, -1.2 and -1.4 MPa), pH (4, 5, 6, 7, 8, 9), burial depth (0, 1, 2, 3, 5, 7, 9, 11, 13, 15 and 17 cm) and flooding duration (0, 3, 5 and 7 days) were examined.

Constant and alternating temperatures had a significant effect on the germination percentage of common morning-glory. The highest germination percentage were observed at constant temperatures of 30 and 35 °C and at alternating temperatures of 15: 25 and 20: 30 °C (day / night). Based on the Dent model, Cardinal temperatures of seed germination of this plant including base, optimum upper and lower and ceiling temperatures were 7, 30, 35 and 44 °C, respectively. Germination of of common morning-glory seeds decreased with increasing salinity and drought. The concentrations of sodium chloride and polyethylene glycol, which reduced the germination of this plant by 50%, were equal to -1.06 and -0.45 MPa, respectively. This indicates that this plant is resistant to salinity and there is a possibility of its development in saline lands of the country. Germination of this plant in pHs of neutral and alkaline were significantly higher than acidic pHs. At high temperatures, the percentage of germination and seed viability decreased significantly. The percentage of common morning-glory seed emergence at burial depths of 1 to 7cm were not significantly different (92 to 100%). With increasing depth from 9 to 13 cm, the percentage of emergence decreased significantly and no seeds emerged from a depth of 15 cm. Therefore, the use of non-tillage and low tillage methods can not have much effect on the management of this weed; Unless deeper plowing is used. Results showed that seed germination of this plant is very sensitive to flooding stress.

The results of the present study showed that environmental factors have a significant effect on the germination and emergence of common morning-glory and they can be used in designing effective management scenarios to control of this weed.

Maize (Zea mays L.) is the most important silage plants in the world because of its high yield, high energy and quality forage and low fibr. Due to the severe water shortage in Iran and the high water demand of corn crop, the only way to increase corn production is to increase the yield per unit area and reduce the yield gap by optimizing production management. Therefore, this study was aimed to estimate the potential yield and yield gap in the main forage maize production areas in Iran. For this purpose GYGA protocol method was used. Yield potential based on the data from a 15-year period (2001-2015) was calculated using the SSM-iCrop simulation model. Before use, parameterization and evaluation of the simulation model for the studied plant were performed using data from all over the country. In the major maize production regions of Iran, 27 reference weather stations (RWS) and 11 main climatic zones (CZ) were selected. The average Ya and Yp of maize in Iran was estimated at 49.3 and 85.6 ton ha-1, respectively. Furthermore, in the major climatic zones was 9.9 ton ha-1 yield gap in the country. In fact, forage yield and production in Iran can be increased from current 49 ton ha-1 and 11.2 million ton to 68 ton ha-1 and 15.6 million ton through optimized management and elimination of exploitable yield gap.

Common bean (Phaseolus vulgaris L.) with 20-25% protein and 50-56% carbohydrate content, has a crucial role in supplying the required proteins and maintenance of food security of the community. Among the Asian countries, China, Iran, Japan and Turkey are the major producers of common bean. According to the figures provided by the Ministry of Agriculture, cultivation area and production of bean in Iran in 2016 were 114593 ha and 222705 tones, respectively. In recent years, due to the increase in the population and in order to rapidly meet the demand for more food as well as decision making at micro and macro-levels, simulation of crop growth and yield using the models has gained attention due to rapid preparation of the results, lowering the execution costs and the possibility of simulation under various climatic and management conditions. In order to model the growth stages and yield of bean using the figures of Iranian meteorology organization (minimum and maximum temperatures, radiation and rainfall), a study was conducted at Gorgan University of Agricultural Sciences and Natural Resources. The simple SSM_iCrop2 model was used for this study. This model has been tested and proved for a wide range of plant species. This model requires easily available and limited input information. The aim of this study was to parameterize and evaluate the SSM_iCrop2 model for simulation of growth and yield of common bean in order to investigate the effect of climatic, soil and crop management factors as well as determination of genetic coefficients under Iran conditions using the sub-models associated with phenology, dry matter production and distribution and the changes in leaf area.
 
SSM_iCrop2 model was used as the base of this study. Observed and simulated yield and days to maturity values were compared for parameterization and evaluation of the model. For this purpose, a series of experimental data (data associated with the growth and production of bean and reports from the published and unpublished papers) in major bean cultivation areas of the country were used. First, parameters related to phenology, leaf area, dry matter production, yield formation and water relations were estimated. Then, the model was evaluated using a series of data which were independent from the experimental data used for parameterization. Crop management inputs were also entered according to the experiment reports. For statistical analysis and investigation of model precision in comparison of the data recorded in the previous studies with the data simulated by the model, correlation coefficient (r), root mean square error (RMSE) and coefficient of variation (CV) were calculated and 1:1 diagram was also drawn.
 
In parameterization of SSM_iCrop2 model for bean, the comparison of observed and simulated days to maturity with RMSE, CV and r values of respectively 14 days, 13 percent and 0.76 and comparison of observed and simulated grain yield with RMSE, CV and r values of 62 g m-2, 20 percent and 0.84 indicated the accuracy of the used parameters. Furthermore, in the evaluation stage, RMSE, CV and r values for days to maturity were 8 days, 8 percent and 0.74 and for grain yield were 53 g m-2, 19 percent and 0.77, respectively, which confirms the precision of the model simulation. The model simulated the evapotranspiration of been in a good manner. The values for RMSE, CV and r for the comparison of the observed and simulated evapotranspiration were 63 mm, 11 percent and 0.85, respectively. Application of SSM_iCrop2 model is simple and acceptably precise simulation is possible with minimal parameters and inputs. This model was able to simulate the growth period and yield of bean cultivars in a good manner despite high variations using thermal unit parameters form sowing to harvest, maximum leaf area and maximum harvest index.
 
Growth and yield of bean was successfully simulated using SSM_iCrop2 model using minimal and available parameters despite different growth habits and high phenotypic and genotypic variations among the cultivars. The results of the model evaluation performed using RMSE, r and CV showed that this model is able to simulate maturity time and grain yield of bean sown in various dates under Iran climatic conditions with a high precision. Thus, due to suitable precision of SSM_iCrop2 model in simulation of bean phenology and yield, it may be used as a suitable tool for investigation of crop systems and interpretation of results under various environmental and management conditions for planning and improving the management of bean fields in the country.

Germination is the most vital period in the plant life cycle that is influenced by various environmental and genetic factors. Among environmental factors, drought stress can greatly affect the germination and emergence of seedlings. The tolerance to this stress in the early stages of plant development is very important and seeds that can germinate in these conditions will have a successful establishment, proper density and high yield. Therefore, knowing the drought tolerance threshold in different genotypes of a plant can be very useful in recommending their cultivation in different regions. The hydrotime model is one of the common experimental models in studying the effects of drought stress on seed germination. This model has three parameters including base water potential, hydrotime coefficient and sigma, which indicate drought tolerance, germination rate and germination uniformity, respectively. These coefficients, especially the base water potential, can be used to introduce genotypes for cultivation in areas with different drought levels. Therefore, this study was conducted to investigate the response of different quinoa genotypes to drought stress at the germination stage with the help of hydrotime model coefficients.

To investigate the effect of drought stress on seed germination of different quinoa (Chenopodium quinoa Willd) genotypes, a factorial experiment was designed and conducted in a completely randomized design with four replications in the seed laboratory of Gorgan University of Agricultural Sciences and Natural Resources in 2019. For the germination test, 4 replicates of 25 seeds of each genotype were placed in a petri dish with a diameter of 8 cm on a layer of filter paper which added 3 ml of solutions prepared in different water potentials (0, -0.4, -0.8, -1.2 and -1.6 MPa) in an incubator at 25 °C. Depending on the germination rate, in the first days after the onset of germination, the number of germinated seeds was counted three to five times per day; with decreasing the germination rate, the number of counts was reduced to two times per day. The germination criterion was the radicle existence of one millimeter or more. The hydrotime model was used to investigate the germination response of quinoa genotypes to drought stress.

The results showed that all genotypes had high germination up to -0.4 MPa and their average germination percentage was above 90%; But as the water potential became more negative, the difference between the germination percentage of genotypes increased. According to the hydrotime model, there was a significant difference between different quinoa genotypes in terms of base water potential for 50% germination (ψb50), hydrotime coefficient (θH) and germination uniformity (σψb). The value of the ψb50 parameter ranged from -1.58 in genotype2 to -1.95 in genotype3. This indicates that quinoa is drought tolerant at the germination stage compared to sunflower, barley, wheat, safflower and canola. The lowest and highest hydrotime coefficients were observed in genotypes2 and 3 with 16.83 and 26.08 MPa/h, respectively (with an average of 20.93 MPa/h). Quinoa hydrotime coefficient is lower than rapeseed, wheat and safflower; In other words, the germination rate of the seeds of this plant is higher compared to the mentioned crops. The reason for this may be related to the size of the seed. The lowest germination uniformity was in genotype 3 (0.68 MPa) and the highest value observed in genotype 7 (0.46 MPa). The hydrotime and sigma coefficients are considered as indicators of germination rate and uniformity. The lower values of these coefficients are indicated the higher the germination rate and uniformity of the genotype, the faster the canopy closure and the higher yield.

In general, the results of this study show that the seeds have a high germination rate and with a high tolerance to drought stress at the germination stage; This increases the chances of faster establishment in the water shortage conditions. Also, the ability to tolerate drought in the germination stage of quinoa reduces the need for water consumption in this stage, which can be very useful and practical in developing management plans that lead to increased water use efficiency.

The present study tries to estimate the yield gap of irrigated canola in Iran as the first step for planning sustainable improvement of production. It has been performed in the modeling laboratory of Gorgan University of Agricultural Sciences and Natural Resources in 2017-2019. The protocol provided by the GYGA project is used for detection of climatic zones as well as major weather stations in canola production regions to estimate the yield gap. The actual yield of the irrigated canola in its major production regions is between 1184 to 2358 kg ha-1. The range of potential yield is estimated between and 3823 and 6520 kg ha-1. The highest potential yields belongs to Hamedan and Lorestan provinces and the lowest value to Khuzestan Plain. The range of the yield gap in its major production regions in the country is 2480 to 4365 kg ha-1, i.e. 53% to 77% of gap and with an average, 3276 kg ha-1 equal to 65% of the gap. With respect to the exploitable yield as the target yield, the exploitable yield is between 1544 and 3208 kg ha-1, with an average of 2261 kg ha-1. The magnitude of this gap indicates that the potentials of canola production in Iran are not exploited properly. Analyzing the reasons and methods of amendment the present yield gap and adoption of efficient management methods to achieve higher yields is crucial with regard to food security and economic.

One of the strategies to increase the yield per unit area is to use suitable cultivars that are compatible with the climatic conditions of each region at the appropriate planting density, so that there is minimal competition between plants. Determining the appropriate crop density for rapeseed cultivars is very important and plays a decisive role in achieving the desired yield. Planting the crop for each plant and cultivar should be done in a density where the plant is well emerge, establish and in each stage of growth, has enough space to maximize the use of environmental factors and not face unfavorable conditions as much as possible.

This factorial experiment was conducted in a randomized complete block design in research farm of Gharakhil Agricultural Research Center, Ghaemshahr in 2017-2018. Treatments included: densities of 42, 66, 88, 114 and 133 plants m-2 and four rapeseed cultivars including: Hyola 401, Agamax, Hyola 4815 and Trapper which were performed in three replications. The evaluated traits included growth indices such as total dry matter content, leaf area index, crop growth rate, relative growth rate and net photosynthesis rate as well as yield.

The results showed that the interaction effect of cultivar and plant density was significantly different only for total dry matter and leaf area index. Maximum amount of total dry matter (910 g m-2) and leaf area index (3.53) was observed in Hayola 401 cultivar and density of 88 plants m-2 and minimum amount of total dry matter (393 g m-2) and leaf area index (2.26) was observed in Trapper cultivar at a density of 42 plants m-2. According to the results, the only simple effect of density was significant on crop growth rate, relative growth rate and net photosynthesis rate, according to which the highest crop growth rate with an average of 11.36 g m-2 d-1 was related to the density of 88 plants m-2 and the lowest one was obtained with an average of 5.91 g m-2 d-1 from a density of 42 plants m-2. Also, the maximum relative growth rate and net photosynthesis rate with an average of 0.0580 g g-1 d-1 and 3.49 g m-2 were obtained at a density of 88 plants m-2, respectively, and their minimum ones with an average of 0.0530 g g-1 d-1 and 2.99 g m-2 was seen from the density of 42 plants m-2. The highest grain yield with an average of 7031.8 kg ha-1 was related to Hayola 401 cultivar in a density of 88 plants m-2.

With increasing density of 42 plants m-2, dry matter production and leaf area increased; when the highest amount of dry matter and leaf area index in cultivar Hayola 401 in density of 88 plants m-2 had the best results and the highest rate of crop growth rate, relative growth rate and net photosynthesis rate were obtained at density of 88 plants m-2. Therefore, in low densities, due to the lack of complete canopy closure and low surface for radiation absorbance (leaves), dry matter production had decreased, while with increasing density more than 88 plants.m-2 due to increase intra specific competition, dry matter production and leaf area index decreased. Therefore, according to the results, planting cultivars Hayola 401 at a density of 88 plants m-2 is recommended to achieve high yields in the climate of Mazandaran.

To evaluate the effects of climate change on irrigated wheat yield, Cv. Mehregan, under drought stress condition, a completely randomized block design (CRBD) experiment was carried out during 2019-2020 cropping season in Varamin, Iran. Five treatments of Control (T1), without stress, drought stress in booting stage (T2), flowering stage (T3), milking stage (T4) and doughing stage (T5) were assigned to three replications. In this study, simulation of the future climate, 2025 and 2055 (2010-2039 and 2069-2040), were performed using the outputs of HadGEM general circulation model under RCP4.5 and RCP8.5 climate scenarios. For this purpose outputs of AgMIP model were employed using long-term climatic data of the base period (1980-2009). Based on these findings, under RCP4.5 and RCP8.5 scenarios, the minimum and maximum temperature parameters might increase for the 2025 and 2055 periods. Also, under RCP4.5 scenario rainfall might increase by 9.4% and 21%, for 2025 and 2055 periods, respectively. However, under RCP8.5 scenario, it might decrease by 1.9% and 2.8%, respectively. Drought stress shortened the phonological stages, the number of days after planting to flowering, ripening and the grain filling periods under climate change conditions. The results also showed that under RCP4.5 scenario in 2025 period the highest decrease in dry matter (4 percent) and seed yield (10.2 percent), due to stress condition, occur during booting and flowering stages, respectively.

Barley (Hordeum vulgare L.) is considered as the second most important grain crop after wheat, due to 1.75 million hectares harvested areas and 3.2 million tons’ production in Iran. The irrigated fields are contributed up to 45% of total barley harvested areas (equivalent to 1.7 million ha) and 70% of total barley production (equivalent to 2.2 million tons). Based on the statistics reported in recent years, about 2.5 million tons of barley imported from other countries. According to the impossibility of extending the barley cultivated areas and even the necessity of reducing fields in some parts of the country, increasing productivity per unit area of cultivated lands is recognized as the only practical way to boost the production of barley in Iran. In this regard, this study was conducted to estimate barley yield gap (Yg) and the potential of increasing barley production in irrigated condition as the first step to promote the yield and production of barley over the country.

Firstly, the main production zones of barley are determined; the zones which were contributed in more than 85% of barley production. The Designated climatic zones (DCZs) were identified using GYGA climatic zones (Global Yield Gap Atlas) and the distribution of barley harvested area raster layers. Subsequently, the Reference weather Stations (RWSs) within the DCZs were selected based on the values of the harvested area, and the types of soil in each of RWSs were determined by using of HC-27 soil map. SSM-iCrop2 as a crop simulation model has been employed to estimate the potential yield (Yp) in the RWSs of cultivated areas, which has previously been parameterized and evaluated, and the results have indicated the robustness of the model for simulating barley yield over the country. For estimating Yg, the data of actual yield (Ya) and the agronomic management data for estimating Yp during 15 growing seasons (2000-2014), were collected at RWSs scale. Using A bottom-up approach, the yield, and production gap values were calculated at RWSs and subsequently aggregated to DCZs and finally, extended from DCZ to country-level according to the spatial distribution of crop area and climate zones.

Based on GYGA protocol, 48 RWSs within 12 DCZs of irrigated barley harvested areas were demonstrated. Aggregation from the RWSs results to DCZs illustrated that the average of potential yield in DCZs of irrigated barley was estimated 7090 kg.ha-1 and the range varied from 5283 to 8286 kg.ha-1. Nevertheless, the Ya range in these climate zones was calculated between 1406 and 3723 with an average of 3009 kg.ha-1. According to the results, the DCZs which confronted to higher temperatures during the growing season have lower yields and also a significant reverse correlation between the potential yield and the growth length period (R2 = 0.88 and p ≤0.01) were shown. The correlation between total received daily solar radiation during the growing and Yp in the DCZs was significant, positively season (R2 = 0.98 and p ≤0.01). At present, the range of difference between actual and potential yield varies between 3237 to 4697 kg.ha-1 with an average of 4081 kg.ha-1 (equivalent to 58% yield gap). In other words, just around 24 to 50 percent (on an average of 42 percent) of estimated Yp in irrigated barley fields can be attainable. According to the irrigated barley harvested areas, the actual and potential production gap are calculated about 2.21 and 2.99 million tons in the country, respectively, and under the best management condition can lead the production to be about 4.17 million tons.

According to the results, it was demonstrated about 58% relative yield gap between the averages of actual yield (3008 kg.ha-1) and potential yield (7090 kg.ha-1), which can be reduced by improving the production management in irrigated barley cultivated areas. For this reason, the current production of barley in irrigated lands can be increased from 2.12 to 4.17 million tons. This increase in production (1.96 million tons) could provide a significant part of the country's need to the barley and bring the country closer to achieve full self-sufficiency.

Due to limitation of water and soil resources resulted from geological and climatic conditions of Iran as well as necessity of self-reliance in infrastructural issues, efficient usage of water and soil resources available in Iran is inevitable. Climatic changes, reduced biodiversity in the region and concerns about food security are regarded as important issues; hence, evaluation of conditions to attain improved crop production seems essential. To investigate yield improvement methods, yield potential and yield limiting factors (climate, soil, water, and genetic factors) should be determined and evaluated in the first step. Simulation models may be used as scaled-up designs of field experiments to overcome limitations such as time and costs. Crop  simulation  models  are  mathematical representations  of  plant  growth  processes  as  influenced  by  interactions  among genotype,  environment and crop  management. Using crop simulation models can be an efficient complement to experimental research.  Models are being used to understand the response of crops to possible changes in crop, cultural management, and environmental variables. Crop models use various plant and environmental parameters to simulate crop growth and should be calibrated and evaluated before usage.

 SSM-iCrop model predicts phenological stages as a function of temperature, day length.  Calculation of phenological development in the model is based on the biological day concept. A biological day is a day with optimal temperature, photoperiod, and moisture conditions for plant development. Leaf  area  development  and  senescence  is  a  function  of  temperature,  provide nitrogen  for  leaf  growth,  plant  density  and  nitrogen  remobilization.  To  simulate leaf area expansion, the first step is to determine on each day the  increase in leaf number  on  the  main  stem  using  the  phyllochron  (temperature  unit between emergences of successive leaves) concept. In this model biomass is estimated as a function of the received radiation and temperature.  Daily  increase  of  crop  mass  is  estimated  as  the  product  of  incident photosynthetic  active  radiation  (PAR,  MJ  m-2d-1),  the  fraction  of  that  radiation intercepted  by  the  crop  (FINT)  and  efficiency  with  which  the intercepted  PAR  is used to produce crop dry mass, i.e., radiation use efficiency (RUE, g MJ-1).  Yield formation  in  the  model is simply  simulated  as  total  dry matter  production  during seed  filling  period  plus  a  fraction  of  crop  dry  mass at  BSG  (as  mobilized  dry matter).  Modeling  seed  growth  rate  and  yield  formation  in  the  current  model  is based on a modified linear increase in harvest index concept as described by Soltani and Sinclair (2011).The model needs daily weather data, i.e. maximum and minimum temperatures, rainfall, and solar radiation. The model can be run under multiple scenarios/treatments over many years.

 As a result of the SSM-iCrop model parameterization, three early, medium and late maturing cultivars were determined for canola, which their cumulative degree days (GDD) for growth period completion were estimated as 2000, 2500 and 2700 °C days. After determination of the required parameters, the model was run based on sowing date, management, and meteorological statistics of the region using the data from the papers which were not used for parameterization, so as to validate the model. The average of the simulated data for days to maturity and yield were 222 (days) and 383 (g.m-2), respectively, whereas observed values for this traits were 223 (days) and 359 (g.m-2).

 Based on the 1:1 line and statistics of r=0.87, CV=18% and RMSE=67.04 (g.m-2) for grain yield and r=0.97, CV=5% and RMSE=10.68 (days) for days to maturity, it may be concluded that simulation canola growth using SSM-iCrop model has been satisfactory and indicates accurate estimation of the model parameters, as well as serving as a verification of the model efficiency in prediction of canola yield under climatic conditions of major canola production regions of Iran.

Potato (Solanum tuberosum L.) accounts for the largest share in production of food products after wheat, rice and corn, which plays an important role in the nutrition and food basket of the world. Currently, the issue of food security and supplying is very important in different parts of the world and thus prediction of its demand that is increasing. Also, growing population will intensify this issue too. A key strategy to overcome the nutritional challenge of the growing population of the world is eliminating the gap between the current achievement in farms and the yield which can be achieved by using the best cultivars compatible with the environment and the best water, soil and plant management methods.

In this study, potential yield of potato was estimated using the SSM-iCrop2. then the production and yield gap of potato were investigated with two methods of Global Yield Gap Atlas (GYGA) and Arc GIS software by interpolation method for Golestan province. For this aim, the information of potato cultivation management in the province level and the daily data of 23 synoptic weather station as well as their soil data were used. Meanwhile, potential yield gap analysis protocol (GYGA protocol) was used to identify the main weather stations named reference weather stations (RWSs) and climates where potato is planted in Golestan province. Potential yield of potato was estimated within the area covered by each RWS, and then scaled up to the province level. In order to implement the interpolation method in ArcGIS software, initially, potential yield of 23 stations in the Golestan province was estimated. Afterwards, the potential and actual yield in the whole province was estimated using Kriging and IDW methods, respectively.

According to the Agricultural Jihad Report, the actual yield of Golestan province (a ten-year average) was reported as 22 t.ha-1, while the actual yield calculated based on the interpolation method was estimated equal to 22 t.ha-1. However, the actual yield calculated using the global yield gap atlas (GYGA) method was estimated as 20 t.ha-1. Heigh yield of potato in the province was reported by farmers up to 55 tons, which was considered as potential in the province to be compared with GYGA and interpolation methods, so that in the GYGA method, 52 t.ha-1 and in the interpolation method, finding was 42 t.ha-1. yield gap and relative yield in the GYGA method (33 t.ha-1 and 38 percent), and interpolation (20 t.ha-1 and 52 percent) were obtained. Also, in GYGA method, the values ​​were estimated using only two stations, but in the interpolation method the province's yield was estimated using 23 stations and daily meteorological data. The GYGA protocol is a bottom-up approach used by Hochman et al. (2016) to assess the variation of national yield from climatic zoning to analyze similar agro-cluster groups. So far, several studies have been done using this protocol. Gobbett et al. (2017) showed that wheat lands in Australia are located in six key climatic regions. They selected 22 reference stations in this area and calculated the limited water potential yield using the APSIM model (for the years of 1996 to 2010).

The results showed that both Global yield gap Atlas (GYGA) and interpolation method had accurate estimation of actual and potential production and yield, but those values obtained using statistics and 23 weather stations in the interpolation method, and using just 2 weather station (Hashemabad and Gorgan stations) in the Global Atlas method. As previously mentioned, the GYGA method is designed to estimate the yield gap at the national level, which can calculate the potential yield, production, and yield gap in a wide range even with the least amount of information. One of the advantages of GYGA protocol is that the results obtained at any point in the world are comparable to other areas and cultivations of that particular product. Based on the comparison made in this study, it was concluded that the Global yield gap Atlas method should be used to estimate the yield of the country.

The present study was conducted to parameterize the SSM_iCrop model and evaluate the prediction of growth and development of faba bean in Gorgan climate condition. This study was carried out on faba bean cv."Barkat" as split-plot in randomized complete block design with four replications at Gorgan University of Agricultural Sciences and Natural Resources in 2015-2016. The experimental factors consisted of planting date (27 November, 25 December and 31 January) and plant density (5, 15, 25 and 35 plants/m2). The parameters of phonological stages, leaf expansion and senescence, production and distribution of dry matter and water balance were estimated using the present data experiment and other data. The results of model evaluation showed that, it can well predict, days to flowering (RMSE = 3.8 and CV =4.1), days to maturity (RMSE = 11.9 and CV= 8.1), node number on main stem (RMSE = 1.7 and CV = 10.0), leaf area index (RMSE =0.8 CV =28.8), biological yield (RMSE = 158.5 and CV =21.6) and seed yield (RMSE = 118.6 and CV = 24.7). Therefore, the SSM_iCrop model can be used to evaluate the agronomic management and analyze the growth and yield of faba bean in Gorgan conditions.

Seeds, like other materials, are hygroscopic and exchange moisture with their surroundings. The changes in the moisture of seeds during storage depend on their hygroscopic nature and this feature plays an important role in determining the seed quality and longevity. Furthermore, studying the hygroscopic characteristics if seeds can be useful in seed storage studies as well as in commercial applications such as drying and seeds processing. Therefore, in this study, the relationship between seed moisture content and relative humidity in seed of rapeseed cultivars was studied.

In this study, the relationship between the ambient relative humidity and seed moisture content of three rapeseed cultivars at 10, 20 and 30 °C was investigated using hygroscopic equilibrium curves. Therefore, water desorption and absorption curves were studied separately. Water absorption and desorption curves were obtained by drying the seeds at 1% relative humidity and seed hydration at 100% relative humidity, respectively, followed by transferring the seeds to different relative humidities at different temperatures and finally determining the equilibrium moisture content of the seeds. It should be noted that glycerol and sulfuric acid solutions were used to creation different relative humidity. Finally, the relationship between seeds moisture content against the relative humidity was quantified by fitting the D’Arcy-Watt equation.

The results indicated that the seeds moisture content varied in cultivars and temperatures at different relative humidities. Also, there was a difference between water desorption and absorption curves in all cultivars and temperatures; desorption curves were generally higher than water absorption curves. The greatest difference among the cultivars regarding seed moisture content was observed at 100% relative humidity, and this difference was less severe at lower relative humidities. Also, the highest seed moisture content of rapeseed cultivars was observed at 20 °C and 100% relative humidity, and the lowest seed moisture content was recorded at 30 °C and 1% relative humidity.

According to the results, it was found that the relationship between seed moisture content and relative humidity followed a sigmoidal function, and this relationship would also vary depending on cultivar and temperature. There was also a difference between the adsorption and desorption curves, which is called "hysteresis", and showed that the seed moisture content at a constant relative humidity was generally higher in the state of dehydration compared with that in the state of hydration. Due to this event, desorption curve is situated higher than the absorption curve.

Response to hygroscopic equilibrium curves in seeds of different rapeseed cultivars was compared. Sulfuric acid and glycerol solutions were used to create different relative humidity.