جستجوی مقالات مرتبط با کلیدواژه « نیاز آبی » در نشریات گروه « اکولوژی »

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.

This study is to investigate the effect of Thiobacillus inoculant and sulfur bio bacteria on less water stress in Khatouni melon plants.

the aim of the experiment was conducted with split plots in a three-replication randomized complete block design.Irrigation regime as the main plot with levels of 100, 75 and 50%of melon water requirements and fertilizer treatments as a sub-plot with three levels of thiobacillus (without inoculum, 250 and 500 kg sulfur per hectare along with 5 and10 kg of bacterial with a population of 107 bacteria per gram inoculum).

The results study indicate that all studied agronomic traits affected by stress, so that drought stress had a significant impact on all traits. On the other hand, sulfur plus thiobacillus reduced the negative effects of water stress and led to significant increases in total chlorophyll content, carotenoids, number of fruits per plant, and fruit weight at various levels of drought.Thus,application Third level of sulfur, A significant effect of drought stress interaction with the sulfur application was seen on all traits studied except for conductance at level of one percent.

The application of sulfur and thiobacillus can improve growth traits and increase yield, irrespective of its irrigation level. Moreover, the use of sulfur and thiobacillus in the treatment of dehydration results in 75% of the water requirement of 500 kg sulfur per hectare with 10 kg of Thiobacillus. It was also observed that with increasing dehydration stress , effect of sulfur and thiobacillus on improving growth traits declined.

Following climate change, drought stress has become the most important limiting factor for crop production and. Plants become under dry when the water available to the roots is limited or the water loss through transpiration is very high. Decreased photosynthetic active radiation absorption, impaired light consumption efficiency and reduced harvest index are the most important factors reducing yield in soil moisture deficit conditions. On the other hand, the adverse effects of the use of chemical drugs in recent years have led to much attention to the cultivation of medicinal plants, which with the increase in their use requires the development of cultivation, management and proper planning. Bio-fertilizers as an alternative in some cases and in most cases as a complement to chemical fertilizers can help to ensure the sustainability of agricultural production systems.

 The study was aimed to evaluate the effect of nitroxin biological fertilizer on ecotypes of black cumin under drought stress. The experiment was conducted as a split-split plot with three replicates at Ilam University during growing season of in 2018. Drought stress levels including no stress (Irrigation based on 100% of plant water needs), moderate stress (Irrigation based on 50% of plant water needs) and severe stress (Irrigation based on 35% of plant water needs) as main plot, nitroxin fertilizer treatments including no nitroxin (control) and application of 1 liter ha-1 nitroxin as sub plot and ecotype treatments including Neyshabour, Mashhad, Semirom and Isfahan Sub-plots were considered as sub-plots. Measured traits included plant height, number of sub-branches, yield, grain yield components (number of follicle and number of seeds per follicle), relative leaf water content, ion leakage and photosynthetic pigments.

 The results showed that the main effect of drought stress, nitroxin and ecotype on all treats were significant (p≤0/01). The highest plant height and the first sub-branch height of Mashhad ecotype were obtained under Irrigation based on 100% of plant water needs conditions under moderate stress. The highest number of branches per-plant of Neyshabur ecotype was obtained under nitroxin under drought stress conditions. The highest number of capsules per plant was obtained from Mashhad ecotype treatment with no nitroxin and Irrigation based on 100% of plant water needs. The highest number of seeds in main capsule, seed yield and harvest index were obtained from Semirom ecotype under nitroxin under Irrigation based on 50% of plant water needs. The highest biological yield was obtained in Isfahan ecotype, nitroxin consumption and Irrigation based on 50% of plant water needs.The results of this study showed that drought stress caused a significant reduction (p≤0.01) in the values of chlorophyll a, b and total chlorophyll traits and relative moisture content of leaves Meanwhile, the use of nitroxin biological fertilizer in most cases improved these traits in different ecotypes, which can be due to the positive effects of biological fertilizer in helping to better absorb water and nutrients under drought stress and reduce the negative effects of water deficiency on Physiological traits of the plant.

 Since better absorption of nutrients depends on the existence of an extensive root system, it seems that the lack of expansion of the plant root system under drought stress and the lack of use of chemical fertilizers, the ground for the activity of microorganisms. This has led to the improvement of the root system and consequently better absorption of water and nutrients needed by the plant in conditions of moisture stress. In general, the results of this study indicate that the application of biological fertilizers may have had a positive effect on improving the yield and quantitative properties of the herbicide under drought stress conditions, however, this issue needs further investigation. From the results it can be concluded that moderate drought stress can be applied in weather conditions Ilam province in addition to reducing water consumption will lead to better outcomes.

Water scarcity is the main challenging issue in supplying sufficient food in arid and semiarid regions. Agricultural production in Razavi Khorasan, like other arid and semiarid provinces, depends on underground water. Groundwater exploitation alongside climate change has dramatic effects on the availability of surface water for agricultural production in semiarid areas. Crop water use estimation is the first step to increasing Water Use Efficiency (WUE). From the water resource point of view, assessing the gap between actual and attainable crops, WUE is so important, especially for future mitigation strategies. The term water use efficiency refers to production per unit of water used by evapotranspiration, with units such as kg grain/ha per mm water or kg/m3 water, so it does not scale in the 0-1 range. This paper aims to evaluate WUE for main crops (wheat, barley, sugar beet, onion, potato, tomato, cucumber, and watermelon) in the different areas of Razavi Khorasan province (Torbat-e Heydarieh, Torbat-e Jam, Chenaran, Mashhad, Sabzevar, Quchan, Kashmar, Gonabad, and Neyshabour) for 26 years (1985-2010). 

WUE shows crop production per unit of water use. It was calculated as production per unit of crop water used (CWU) by evapotranspiration. CWU was acquired by estimating two components: reference evapotranspiration (ETo) and crop coefficient. ETo was calculated via the Blaney-Criddle equation. Although this method has a coarse accuracy in comparison to other methods, this is ideal when only air-temperature datasets are available. We examined the relationship between yield and CWU, as well as WUE and CWU for wheat, tomato, alfalfa, and sugar beet. A polynomial line was fitted to describe the best relation between two variables. The maximum yield at each point of CWU was determined as the highest attainable yield. Mann-Kendall test was applied to detect the trend of data over time.

The long-term average of WUE showed a similar trend for wheat and barley. The highest wheat WUE was about 0.59 and 0.53 yield per m3 in Torbat-e Jam and Chenaran. Chenaran and Torbat-e Heydarieh had the highest WUE of sugar beet (3.12 and 3.08 kg fresh root per m3). The highest amount of potato WUE (4.05), tomato WUE (4.7), and onion WUE (4.9) were found in Torbat-e Jam, Chenaran, and Chenaran, respectively. Kashmar, Gonabad, and Sabzevar had the lowest WUE for most of the crops. It seems that high temperature during crop growth caused a decrease in WUE in the mentioned locations. WUE of all crops had an intense fluctuation between 1986 and 1996, while it modified in the later years to the extent that a mild increasing slope was found in WUE.A polynomial line was fitted to show yield and WUE changes, then the upper boundary line and the lower boundary line were fitted to represent attainable yield and WUE and minimum yield and WUE. The highest yields were obtained around 540, 880, 940, and 850 mm water use for wheat, alfalfa, sugar beet, and tomato, respectively and the law of diminishing returns was observed between yield and CWU. An increase in temperature caused yield and WUE to decrease. The upper boundary line was more resistant to environmental changes, whereas the lower boundary line was sensitive.The effect of 1 and 2  temperature rise on yield and WUE  was negligible, while with a three  increase, yield and WUE of lower boundary line decreased by 20%. Although a three ℃ increase in temperature had a negligible impact on WUE in the higher boundary line, WUE in the lower boundary line decreased dramatically. Alfalfa was known as the most sensitive, and sugar beet was the most tolerant crop to temperature in terms of WUE.

WUE was negatively associated with mean annual temperature rise. The results indicated that global warming damages yield stability. Yield and CWU showed a positive correlation up to the maximum yield; then, excessive CWU increases led to yield decline. When temperature increases and environmental conditions become worse, appropriate agronomic management such as changing sowing date, balancing crop nutrition, and proper irrigation schemes can play an effective role in enhancing yield. We concluded that when temperature increase, the WUEIntroductionWater scarcity is the main challenging issue in supplying sufficient food in arid and semiarid regions. Agricultural production in Razavi Khorasan, like other arid and semiarid provinces, depends on underground water. Groundwater exploitation alongside climate change has dramatic effects on the availability of surface water for agricultural production in semiarid areas. Crop water use estimation is the first step to increasing Water Use Efficiency (WUE). From the water resource point of view, assessing the gap between actual and attainable crops, WUE is so important, especially for future mitigation strategies. The term water use efficiency refers to production per unit of water used by evapotranspiration, with units such as kg grain/ha per mm water or kg/m3 water, so it does not scale in the 0-1 range. This paper aims to evaluate WUE for main crops (wheat, barley, sugar beet, onion, potato, tomato, cucumber, and watermelon) in the different areas of Razavi Khorasan province (Torbat-e Heydarieh, Torbat-e Jam, Chenaran, Mashhad, Sabzevar, Quchan, Kashmar, Gonabad, and Neyshabour) for 26 years (1985-2010).Material and MethodsWUE shows crop production per unit of water use. It was calculated as production per unit of crop water used (CWU) by evapotranspiration. CWU was acquired by estimating two components: reference evapotranspiration (ETo) and crop coefficient. ETo was calculated via the Blaney-Criddle equation. Although this method has a coarse accuracy in comparison to other methods, this is ideal when only air-temperature datasets are available. We examined the relationship between yield and CWU, as well as WUE and CWU for wheat, tomato, alfalfa, and sugar beet. A polynomial line was fitted to describe the best relation between two variables. The maximum yield at each point of CWU was determined as the highest attainable yield. Mann-Kendall test was applied to detect the trend of data over time. Results and DiscussionThe long-term average of WUE showed a similar trend for wheat and barley. The highest wheat WUE was about 0.59 and 0.53 yield per m3 in Torbat-e Jam and Chenaran. Chenaran and Torbat-e Heydarieh had the highest WUE of sugar beet (3.12 and 3.08 kg fresh root per m3). The highest amount of potato WUE (4.05), tomato WUE (4.7), and onion WUE (4.9) were found in Torbat-e Jam, Chenaran, and Chenaran, respectively. Kashmar, Gonabad, and Sabzevar had the lowest WUE for most of the crops. It seems that high temperature during crop growth caused a decrease in WUE in the mentioned locations. WUE of all crops had an intense fluctuation between 1986 and 1996, while it modified in the later years to the extent that a mild increasing slope was found in WUE.A polynomial line was fitted to show yield and WUE changes, then the upper boundary line and the lower boundary line were fitted to represent attainable yield and WUE and minimum yield and WUE. The highest yields were obtained around 540, 880, 940, and 850 mm water use for wheat, alfalfa, sugar beet, and tomato, respectively and the law of diminishing returns was observed between yield and CWU. An increase in temperature caused yield and WUE to decrease. The upper boundary line was more resistant to environmental changes, whereas the lower boundary line was sensitive.The effect of 1 and 2  temperature rise on yield and WUE  was negligible, while with a three  increase, yield and WUE of lower boundary line decreased by 20%. Although a three ℃ increase in temperature had a negligible impact on WUE in the higher boundary line, WUE in the lower boundary line decreased dramatically. Alfalfa was known as the most sensitive, and sugar beet was the most tolerant crop to temperature in terms of WUE. ConclusionWUE was negatively associated with mean annual temperature rise. The results indicated that global warming damages yield stability. Yield and CWU showed a positive correlation up to the maximum yield; then, excessive CWU increases led to yield decline. When temperature increases and environmental conditions become worse, appropriate agronomic management such as changing sowing date, balancing crop nutrition, and proper irrigation schemes can play an effective role in enhancing yield. We concluded that when temperature increase, the WUE gap will widen, and agronomic management will play a more important role in this condition. gap will widen, and agronomic management will play a more important role in this condition.

The estimation of water demand is one of the most important factors in managing water resources and the necessities of any irrigation and drainage plan. Estimation of the potential of the reference plant (ET) should be estimated to meet the water requirement. The level of utilization of surface water and underground resources in each region is directly related to the water needed to irrigate agricultural products in that area. In this study, which was conducted in the watershed of Yazd-Ardakan plain, OPTIWAT software was used to calculate the need for water. Irrigation and horticultural products of Yazd-Ardakan plain are about 54,000 ha. The water required for irrigation of these three products is 917.6 × 106 m3, which accounts for approximately 70 % of the water needed for irrigation of the total crops in the study area. The amount of water need for irrigation of crops and orchards of Yazd-Ardakan plain was achieved with current crop and current yield (45%) equal to 831.7 × 106 m3. The amount of water required for these products for drip irrigation and efficiency of 60, 75 and 90 percent were calculated 594 × 106 m3, 464.7 × 106 m3, and 382 × 106 m3, respectively. Therefore, it can be concluded that by changing the pattern of cultivation and increasing the irrigation rate, the use of the aquifer in the plain can be reduced and added to the amount of underground storage.

Drought stress is one of the most important factors limiting growth and crop production in the arid and semi-arid world. Plant response to drought stress depends on the type, severity, and duration of stress, plant species, and stress occurrence stage and farm management.
The sesame, among crop plants, is resistant to drought and heat stress and has great importance in the agriculture development of arid and semi-arid region for summer planting. But this plant is sensitive to drought stress at seedling stage and during flowering to grain filling. To overcome the drought stress, the biological solution is one of the basic strategies that should be considered and can be noted the mycorrhizal fungi. One of the most important types of mycorrhizal is arbuscular rmycorrhizal Fungi, which is important in terms of agriculture; because most crops and horticultural ability to coexist with this type of mycorrhiza. In order to evaluate the effect of irrigation levels and arbuscular mycorrhizal fungi symbiosis on yield and yield components of sesame, an experiment was carried out as split-factorial based on a randomized complete block design with three replications at Agricultural Research Station of Haji Abad, Hormozgan province, Iran during growing season 2014-2015. Experimental factors included: drought stress as main factor in 3 levels: 100% water requirement (normal irrigation), 70% water requirement (moderate stress)and 50% water requirement (Severe stress), the priming as sub factor in 3 levels: without priming (control treatment), hydropriming and osmopriming and the mycorrihizal fungi application as other sub-factor in 3 levels: [without mycorrihizal fungi application(control), mycorrihizal fungi application (Glomus mosseae) and mycorrihizal fungi application (G. intraradices). Analysis of variance data showed that the effect of drought stress had significant effect (P≤0.01) on all traits were studied. The effect of mycorrhizal inoculation was significant on measured plant responses (P≤0.01). Priming treatments were significant on seed number per capsule (P≤0.01) and thousand grain weight and grain yield, biological (P≤0.05). Interaction effects of mycorrhiza × irrigation was only significant on grain yield (P≤0.05), the effects of the interaction of mycorrhiza × priming on seed number per capsule (P≤0.01) and the thousand grain weight (P≤0.05) were significant. The results also showed that the highest grain yield and all measured traits obtained when using irrigation water requirement by 100 percent (normal irrigation). Inoculation with mycorrhizal fungi species G. mosseae and G. intraradices compared to lack of mycorrhizal fungi (control treatment) improved yield by 10.4 and 4.7 percent. Priming treatments compared to non-primed (control treatment) increased seed yield by as much as 2 percent. Drought stress decreased sesame yield, however, the using mycorrhizal fungus can be reduced that effect. The effect of two species of mycorrhizal on sesame yield and their effect on reducing stress damage was different; So that mycorrhizal symbiosis G. mosseae has more than the G. intraradices and avoided the sharp drop in sesame yield in drought stress treatments. The results of this study showed that drought stress and water shortage decreased significantly yield and yield components of sesame. Mycorrhizal fungi improved the absorption of moisture and nutrients under water stress and increased plant resistance to water stress, therefore increased yield and yield components of sesame. The species of G. intraradices fungi compared to G. mosseae was more efficient in terms of resistance to water stress. Thus, it seems that mycorrhizal, in addition to improving the yield due to increased root system development and consequently increasing the availability of moisture and access to nutrients, can have a positive effect on reducing the effects of irrigation deficiency on sesame plants. Seed priming, due to better germination, rapid seedling growth, proper establishment and, finally, the optimal use of nutrients and environmental factors, ultimately increased yield.

The semi-tropical plant of saffron, due to low water requirement and high income, has a special place in the cultivating pattern of arid and semi-arid regions such as Torbat Heydarieh region of Khorasan Razavi. In this research was carried out to determine the potential and actual evapotranspiration rate and the most suitable model for estimating evapotranspiration of saffron in Torbat Heydarieh (the world's saffron producing pole). The results of comparison of different methods with FAO method as standard and basic method showed that Blaney-Criddle, Genesis and Hargreaves methods were more accurately than other methods. A comparison of the results of the FAO method with other methods was performed using Chi-square test. The amount of annual water requirement of saffron in the climate of Torbat Heydarieh using the FAO method was 1731 m3 / ha. Since in the Hargreaves-Samani equation, for the calculation of evapotranspiration, only two factors are necessary for temperature and solar radiation, and it is possible to determine the factors in most weather stations, the overall result of this research is that, in the estimation of initial and Rapid need for a saffron plant in the region can be used.

In order to evaluate different irrigation amounts and salicylic acid spraying and determination of principal components in water use efficiency of sesame (Sesamum indicum L.), maize (Zea mays L.) and common bean (Phaseolus vulgaris L.), a split plots experiment based on RCBD design with three replications was conducted in 2014-2015 growing seasons, in Ferdowsi University of Mashhad, Iran. Irrigation levels (50 and 100% of water requirement) and application and non-application of salicylic acid assigned to main and sub plots, respectively. The result showed that in sesame and maize, the highest seed yield obtained in conditions of salicylic acid application. Variables analyzed to 3 factors in sesame and 2 factors in maize and bean. In sesame, first factor included variables of dry matter yield, plant height, leaf erea index and soil phosphorous, variables of seed yield, seed weight per plant, crop growth rate and water use efficiency were in second factor and variables of EC, soil nitrogen and pH had the highest load in third factor. In maize, variables of seed yield, dry matter yield, seed weight per plant, plant height, crop growth rate, leaf erea index and water use efficiency were on first factor and variables of soil nitrogen, EC, pH and soil phosphorous had the highest load in second factor. In bean, variables of seed yield, dry matter yield, seed weight per plant, crop growth rate, soil nitrogen and phosphorous, EC and water use efficiency were in first factor and second factor included variables of leaf erea index, plant height and soil pH. In general, in all three plants, water use efficiency and effective variables in seed yield were in same factor, therefore it seems that any change in these variables will result in a direct change in water use efficiency.

Evaluation of water requirement in designing irrigation systems and water supply in agriculture is important. The aim of this study was to estimate and determine the spatial pattern of water requirement of apple tree using weather stations statistics from 1985 to 2013 in apple tree cultivation areas in Iran. Initially, annual reference evapotranspiration was estimated based on the FAO, Penman-Monteith model, In the following, the stages of growth the summer apple Kohanz crab and autumn apple Red-Delicious were identified. Eto calculation annual results and water requirement of growth stages were identified using ArcGIS10.2 as a spatial pattern for each variety. The results showed that the annual ETo in the North-Eastern and Southern regions of the apple cultivation area cultivar reaches more than 2000 mm. The summer apple Kohanz crab has less water requirement than autumn apple Red-Delicious varieties and the middle stage of growth in apple trees have the highest water requirement. The spatial changes in evapotranspiration and water requirement apple trees are due to altitude factor. From the north to the south and from the West to the East, the apple cultivation areas in Iran increases the amount of water requirement.

Plants may be exposed to various stresses and water deficit is the most important limiting factor of growth and yield in many parts of the world and Iran. Stress induced growth decrement can be because of cell development decrease due to decrement of turgor pressure and meiosis and photosynthesis decrease due to stomata closure. Determination of desired planting density is one of the success factors of plant growth and production. Garlic (Allium sativum) has been an important medicinal plant over centuries in human life. According to the importance of medicinal plants and studying the effects of drought stress on them, the goal of this research is to investigate the effect of drought stress and planting density on growth and morphological characteristics of two ecotypes of garlic and determining the preferable ecotype and density from the perspective of these traits.
This experiment was performed in 2012 in a farm in south east of Semnan. It was conducted on a split-plot factorial arrangement based on randomized complete blocks design with three replications. Three levels of drought stress with 60, 80 and 100 percent of crop evapotranspiration (ETc) were the main plot factors and factorial combination of three planting density (30, 40 and 50 plants.m-2) and two ecotypes of Tabas and Toroud were the levels of sub plot factors. To estimate water requirement of garlic, daily measured meteorology parameters of Semnan synoptic station were used and water requirement was calculated based on FAO-56 instructions. From mid-January, the sampling of leaf area, bulb and leaf fresh and dry weight was started with destructive method every other week and continued until middle of Jun. three plant were selected randomly from each plot in each turn. From middle of May, height and number of leaves were measured. Leaf area measurement was done by leaf area meter (Delta-T). To estimate growth indices, dry weight of aerial and underground organs and leaf area from measured samples of treatments were used.
The results showed that the highest value of maximum leaf area index (LAI), maximum total dry matter accumulation (TDM), maximum crop growth rate (CGR) and maximum of net assimilation rate (NAR) were observed at 100% ETc with the value of 5.537, 387.53 gr.m-2, 10.47 gr m-2day-1 and 4.92 gr.m-2leaf.day-1 respectively; and by applying the irrigation treatment of 80% ETc these values decreased to 3.745, 262.60 gr.m-2, 6.31 gr.m-2day-1 and 3.71 gr.m-2leaf.day-1 respectively. Drought stress can decrease cell development and division and plant photosynthesis, and thus, it can decrease leaf area index and consequently decrease light absorption, photosynthetic area, dry matter and crop growth rate. Difference between ecotypes in terms of number of leaves, maximum total dry matter accumulation and maximum crop growth rate was significant. Maximum crop growth rate (CGR) in Toroud ecotype was higher than Tabas ecotype but number of leaves and maximum concentration of total dry matter (TDM) in Tabas ecotype were higher than corresponding values in Toruod ecotype. The effect of planting density on maximum leaf area index (LAI), maximum total dry matter (TDM) and maximum net assimilation rate (NAR) was significant. The highest value of maximum leaf area index (5.017) and maximum total dry matter (358.57 g.m-2) concentration were obtained from 50 plant.m-2 density. The highest value of maximum net assimilation rate (4.61) was obtained from 30 plant.m-2 density. It could be because of having leaves exposed to more light and less shading.
Applying drought stress at the irrigation treatment of 80% ETc decreased studied growth characteristics of garlic. Therefore, it is recommended that garlic should be avoided from facing drought stress and its water requirement must be met as much as possible. In general, under drought stress, two studied ecotypes did not have any preference related to the studied growth characteristics. Higher planting density, due to higher active photosynthetic area over unit area, increased the dry matter in unit area.

The water footprint consider as a indicator of freshwater resources appropriation which brings valuable insight about the environmental impact of a given product. The aim of this study is determining the best country’s province for the potato crop production in terms of fresh water consumption, for this object water footprint indicator was used. To achieve this goal, first data on harvested area, production and yield in major producing provinces were collected for the crop year 2014-15. Then to calculate the water footprint in each province, information such as crop water requirement and effective precipitation were collected separately for each province and finally water footprint components were determined. The results showed that green, blue and grey water footprint devoted most contribution in all provinces respectively. According to calculated total water footprint, Hamedan province is the best region for potato harvesting and Semnan province is the most difficult region for this purpose. Water footprint average for potato production was calculated 527 m3/ton in the country. According to water footprint indicator and provinces potato production, it was determined that in mentioned crop year, Hamedan province by using 338 MCM and North Khorasan by using 18 MCM of water, allocated the highest and the lowest amount of water to this agricultural production respectively.

In the recent years, human activities have led to changes in land use and land cover, consequently, these changes lead to the structure and function of ecosystems. Spatial-Temporal Change Detection of land use is important to understand the relationships and interactions between human and natural resources and to make appropriate decisions Due to changes in land use and land cover occurs in broad surfaces, therefore, remote sensing technology is a useful tool for evaluating changes. The aim of this study is to investigate trend change of land use and land cover of the surrounding of the Zayandeh Rood River, as well as to investigate the water demand for agricultural land use of remote sensing and GIS techniques. For this purpose, the OLI images in 1392 and ETM Landsat images of 1382, after correction and preprocessing required, land use /land cover map were produced using the hybrid classification, based on maximum likelihood image processing in 10 classes. The post-classification methods was used to monitor changes in the period of 10 years. The results showed that in the period, dried, more than 40 percent of the Gavkhooni wetland and Zayandeh Rood, the area as well as suffering damage to the structure and the physical – social and ecological sustainability. 19/2 percent increased was observed in the agricultural land in the western part of the study area when the amount of water consumption in the western part in the period 1382 -1392, 52/59 and 60/22 percent, respectively. After that central part, and the lowest water consumption was calculated for irrigated farming in the eastern part. Salty lands have been developed during this period, more than 90 percent. Urban expansion has occurred in the period 1382 -1392 with an area of ​​552 hectares per year.

Estimating and determining of rice water requirement, being the main cultivate of Rasht region, is crucial for devoting water to this region. Equations which are used to calculate the reference evapotranspiration (ET0) are not match to all climatic conditions, due to their empirical bases. So, it is necessary to clarify proper methods for each region. Crop coefficient (Kc) is also the main parameter for determining each plant’s potential evapotranspiration and subsequently plant water requirement. Hence in this study, evapotranspiration data for grass and rice i.e. Binam and Khazar cultivars were collected in Rice Research Institute of Rash, by using drainable lysimeter at ten-day periods during three consecutive crop seasons. The reference evapotranspiration were calculated and compared with 16 empirical equations results included in Ref-ET software. Significant differences of them have been evaluated using SPSS software. Also, the crop coefficient values were calculated for each variety of rice. In all three equations i.e. Hargreaves, Priestley-Taylor and Penman (FAO 24) have not shown any significant differences. Among three methods, Hargreaves equation is recommended for Rasht region because, this equation as compared with others is a temperature-based method and would consider global warming phenomenon. Also, the average of crop coefficient (Kc) for Khazar and Binam in three consecutive crop seasons were 1.10 and 1.09, respectively.

Optimum uses of water and nitrogen resources are the most important factors in agricultural systems due to limitations of agricultural inputs especially water. In order to investigate the effect of different levels of nitrogen fertilizer and irrigation on efficiency and productivity of water consumption in three crop (sugar beet, corn and sesame) an experiment was carried out as strip split plot based on randomized complete block design with three replications at the Agricultural Research Station, Ferdowsi University of Mashhad during growing season of 2008-2009. The main, sub and strip factors were three species (sugar beet, corn and sesame), three irrigation levels (100, 75 and 50% of water requirement of each crop) and four nitrogen levels (0, 50, 100 and 150 kg.ha-1), respectively. The result showed that the highest water use efficiency was observed as 2.4, 1.8 and 1.5 kg DM.m-3 in corn, sugar beet and sesame, respectively. The maximum water use productivity was obtained for sugar beet (4200 Rails.m-3), sesame (2123 Rails.m-3) and then for corn (1768 Rails.m-3). Interaction effect between water and nitrogen was significant on water use efficiency and productivity for all three studied crops. Water use efficiency declined up to 19% by decreasing 25% of water requirement. Water use productivity decreased in all three studied crops by increasing nitrogen consumption. It seems that high nitrogen level could not be affect on reducing drought stress effects.

In order to study the effects of biofertilizers and different water volume per irrigation on vegetative characteristics and seed yield of sesame (Sesamum indicum L.), an experiment was conducted at the Research Greenhouse of Faculty of Agriculture, Ferdowsi University of Mashhad, during 2009. This experiment was conducted as factorial based on randomized complete block design with three replications. The first and the second factors were biofertilizers (Nitragin, Nitroxin, bio-phosphorus and control) and water volume per irrigation (100, 200 and 300 ml), respectively. The results showed that the simple effects of biofertilizer and irrigation volume were significant (p≥0.05) on plant height, the first internode length, number and dry weight of leaves, dry weight of stem, chlorophyll content and relative water content (RWC) of sesame. Also, interaction between biofertilizer and water volume per irrigation was significant (p≥0.05) plant height and RWC. The maximum and the minimum sesame seed yield were observed in Nitragin and control with 204.4 and 100.0 kg.m-2, respectively. The highest seed yield was observed in 100 ml (202.1 kg.m-2) and the lowest was achieved with 300 ml (170.1 kg.m-2) per irrigation water. Application of biofertilizers enhanced root development and hence availability of moisture and nutrients, particularly nitrogen and phosphorus. On the other hand, since these fertilizers are promote of growth regulator and hence in basement of growth and photosynthesis of sesame. With increasing irrigation volume from 100 to 300 ml, growth of sesame was decreased. Therefore, sesame application of biofertilizers could improve its vegetative characteristics in dry and semi-dry regions.

The limited water resources and available precipitations can be used in water storage process using modern and convenient water and soil management, such as compost, organic fertilizers, and polymers. In this study, the effect of physical soil amendments using superabsorbent polymer (in the four levels of %0, %1, %2, %3), and compost (in the four levels of %0, %0.5, %1, %1.5),on Haloxilon aphyllum plants.in the field condition by means of pots was assessed. The values of different traits including plant height, plant fresh and dry weights and root weight, internodes length and collar diameter were measured. The experiment was completely randomized design (16 treatments and four replications). In comparison with unamended soil, the compost-polymer amended soil showed promoted emergence, establishment and enhanced measured traits in plantlets. Values of plant water requirement index were significantly different compared to the control soil treatment. In Comparison with polymer amendment, the compost amendment shows more enhancements in the average values of the measured traits. However application of both amendments brought about greater results.

Saxual (Haloxylon aphyllum) as one of the main species used in the sand fixation and desertification projects can be grown in a wide range of desert soils in Iran. Considering the ecological needs of plants, including water requirements for establishment and long-term stability, is essential. In this research, biomass (shoot and root), shoot to root ratio (S/R) and canopy size were determined under different soil moisture regimes. One year old plants grown in drainage and weighting lysimeters in natural condition were subjected to three soil moisture regimes, viz. well- watered (100%), low- watered (30%) and less- watered (15%) of total field capacity. For determining the evaporation rate and its role in crop evapotranspiration, a lysimeter was used without vegetation. Water requirement content to reach the soil moisture to optimum level, provided by weighting of lysimeters and use of TDR, weekly. Biomass rate and ratio of shoot to root decrease significantly (P<0.001) with a reduction in soil water content. The effects of different treatments on canopy size were not significantly different. Calculating of the amount of the plant production per unit of water consumpted showed that black saxual (Haloxylon aphyllum) trees, need to 2.4 m3 water for optimal annual growth.