مجله مدیریت آب و آبیاری
سال نهم شماره 1 (بهار و تابستان 1398)

Regarding the problem of water scarcity and increasing demand for water and water supply problems and the high volume of saline water sources along with fresh water resources, the management of salt and sweet water for agricultural production as a way to preserve water In conditions of water shortage. In this study was evaluated the effect of Partial Root-Zone Salinity Stress on the water uptake in silage corn in lysimeter in a greenhouse. The experiment with five treatments including: 1-No stress, control; Salinity stress in all root, 2- Mix, 3- Interval, Salinity stress in half of the root (despite the thin blade),4-Fixed Partial Root-zone Salinity-stress, 5- Alternative Partial Root-zone Salinity-sress in three replications in a complete randomized design. The results showed that the cumulative uptake, root area and root volume were significant at 5% level. In the Mix treatment, the highest accumulation (333.8 mm) and wet biomass (45.7 t/ha) and lowest salinity stress coefficient (Ks=0.89) were observed. In the Alternative Partial Root-zone Salinity-sress treatment, the lowest cumulative uptake (244.0 mm) and wet and dry biomass (34. 9 and 11.3 ton/ha) and the highest salinity stress coefficient (KS=0.65) were observed.Due to the lack of water resources and the lowering of the quality of water in certain conditions, instead of drought stress,It is possible to use salinity stresses using saline water sources (Drainage water produced in irrigation and drainage projects and projects) along with quality water sources.

According to the amount of wheat production in Fars Province and occurrence of drought, application of crop’s residual on agricultural land in form of biochar may improve soil fertility and increase crops yield. Therefore, the current research was conducted to study the effect of different levels of wheat straw biochar and deficit irrigation on wheat growth and yield. The treatments included four levels of biochar (0, 1.25, 2.5 and 3.75 % w/w) and three levels of irrigation (100, 75 and 50 % crop water requirement). Under full irrigation treatment, increasing in biochar to 1.25%w/w was increased crop height by 11.5% in comparison with that obtained in no biochar application. Biochar levels of 1.25, 2.5 and 3.75% w/w increased (decreased) stomatal conductance (green canopy temperature) by 26.8, 31.2 and 37.9% (15.2, 21.4 and 23.4%), respectively, in comparison with that obtained in no biochar application, under full irrigation treatment. Also, the maximum number of tillers per wheat plant (3.7), number of seed per tillers (36.1), 1000 seeds weight (54.1 g) and above ground dry matter (65 g) were observed in 1.25 % w/w biochar treatment, and further increase in biochar declined these parameters in comparison with control as the soil become more saline. It can be concluded that deficit irrigation of 75% crop water requirement and application of 1.25% w/w biochar is recommended due to positive effect of these treatments on yield and yield components.

In order to evaluate the Crop Water Stress Index (CWSI) of potato crop, a split- plot design was carried out in a randomized complete block design in Shahrekord Agricultural and Natural Resources Research Center in the growing season of 2018. This experiment consists of two methods of irrigation (surface and subsurface drip irrigation) in the main plots and four irrigation levels (Full Iirrigation, FI; Regulated Deficit Irrigation, RDI-80; Regulated Deficit Irrigation, RDI-65; and Partial Root-zone Drying PRD-75) in subplots, in three replications for potato (Bourren cultivar) with a period of growth of 120 days. Based on the results, the trend of changes in the CWSI of the crop in irrigation treatments for surface and subsurface drip irrigation was between 0.16 and 0.56 and 0.15-0.49, respectively.The relationship between CWSI and yield (Y) for surface and subsurface drip irrigation was Y = -122.28 CWSI + 82.38 and Y = -101.61 CWSI + 70.97, respectively. The yield of crop for treatments FI، RDI_80، PRD_75 and RDI_65 in surface drip irrigation was 52.1, 48, 31.6, and 23.4 Ton.ha-1, respectively and for subsurface drip irrigation 48.6, 44.3, 29.6 and 21.8 Ton.ha-1, respectively.The maximum amount of water consumed for treatment FI was 4590.2 m3.ha-1. The results showed that in order to achieve the highest yield in subsurface drip irrigation, the potato crop should be irrigated in the range of 0.16 to 0.2 of the CWSI.

Light is one of the main factors regulating plant growth and development. Among different aspects of light, light intensity has a great effect on plant responses, such as plant's water relations. Light intensity in greenhouse is lower than normal in winter and excessive light intensity in the summer. The aim of this study was to evaluate the effect of light intensity on performance, evapotranspiration, water use efficiency of lettuce in a completely randomized design with four treatments and twelve replications in the Park of Science and Technology in Aburaihan campus of University of Tehran. Since blue and red spectra are the main wavebands involved in growth and gas relations, the present experiment was done by using spectra composition of red and blue with a ratio of 70 percent red and 30 percent blue with four different intensities including (T1) 75 μmol.m-2.S-1, (T2) 150 μmol.m-2.S-1, (T3) 300 μmol.m-2.S-1 and (T4) 600 μmol.m-2.S-1. The studied traits included growth characteristics associated with water use efficiency. Based on the obtained results, the highest fresh weight was obtained from T3 and the lowest fresh weight was obtained under light intensity T3 with 73.52 and 17.31 respectively. Increased light intensity caused an increase in dry weight and leaf area. Highest growth simulation was observed under T3. Furthermore, the highest and the lowest water use efficiencies were observed in plants that were grown under T4 and T1.

In this study, different levels of irrigation water, vermicompost and tea-pump were studied on cucumber greenhouse. The experiment was conducted as a split plot in a completely randomized, stacked design. The treatments consisted of three levels of compost tea (25, 50 and 75% vol.), Three levels of vermicompost (1, 1.5 and 2 kg / m2) and three levels of water stress (100, 75 and 50% plant water requirement) Was. Vermicompost was harvested before planting, and compost tea was sprayed on the plant in three stages (30 days, 60 days and 90 days after planting). The results showed that treatments had a significant effect on measured parameters including diameter, length and weight of fruit, plant height, yield and irrigation water productivity at 5% probability level. Reducing water consumption reduced yield and yield components, but there was no significant difference between treatments of 100 and 75% of the water requirement of the plant. The interaction effects of vermicompost, tea-pump and water stress indicate that using 75% water content, 75% vermicompost and compost tea reduce the effects of water stress. The interaction effects of vermicompost and tea-pump have shown that using 100% vermicompost to reduce the yield and its components should reduce the consumption of tea-pump to 50%. But when vermicompost is not used up, it is possible to increase the consumption of compost tea by up to 75%. Therefore, it can be concluded that the effects of vermicompost and its extract on plant growth depend on their concentration.

In the recent years, growth simulation models have been attracted for agricultural engineers in order to predict different crop yields. However, growth simulation of medicinal crops has been rarely studied. In current research, for the first time, the performance of SALTMED model in predicting peppermint yield under different deficit irrigation and salinity conditions was studied. Treatments of water deficit included (100% irrigation requirement (as control), 20 and 40% water deficit) and salinity treatments (control, 2, 3 and 4 dS/m). Calibration of model conducted using control treatment data. After insuring the results, validation of model conducted using other treatments data. Results indicated that model accuracy for predicting peppermint yield was relatively good. The coefficient of determination of model during calibration and validation were 0.953 and 0.801. Studying the separate results showed that the model predicted maximum yield of water deficit levels with higher accuracy than salinity levels. Maximum simulated yield of 20 and 40% water deficit levels were 2.75 and 2.83 ton per hectare while the yield of 2, 3 and 4 dS/m obtained as 2.1, 2.06 and 2.05 ton per hectare.

Date palm is an important horticultural crop in Iran. In this research, after measuring the amount of plant evapotranspiration during first to third years by lysimeter, equal 274.3, 402.7 and 597.2 mm, respectively, plant evapotranspiration was estimated by five methods of FAO Penman-Monteith, FAO Blaney-Criddle, FAO pan evaporation, corrected Jensen-Heise and Hargreaves-Samani. Statistical analysis of linear regression of evapotranspiration equations compared to lysimeter showed that all equations were significant at 1% level of probability. The adjusted coefficient of determination (R2adj) was between 0.94 (FAO pan evaporation) and 0.97 (FAO Blaney-Criddle), while modeling efficiency (EF) varied from 0.93 (FAO Penman-Monteith) to 0.95 (FAO Blaney-Criddle). Minimum and maximum of maximum error (ME) were related to Hargreaves-Samani and FAO pan evaporation equations, respectively. Minimum and maximum of normalized root mean square error (nRMSE) were in FAO Blaney-Criddle and FAO Penman-Monteith equations, respectively. Also maximum and minimum of coefficient of residual mass (CRM) were in FAO Blaney-Criddle and corrected Jensen-Heise equations, respectively. The FAO Blaney-Criddle equation had the most fitting accuracy in Ahvaz region. However, the methods of FAO Penman-Monteith and FAO evaporation pan had also well accurate.

Wheat canopy cover, biomass, grain yield and planting date under deficit irrigation were simulated by AquaCrop in Darab and Zarghan of Fars province. The 2015-2016 growing season and 2016-2017 and 2017-2018 growing seasons were used for model calibration and validation, respectively. Water content, canopy cover, biomass and grain yield were used to determine the calibration parameters in the first year. The calibrated model showed high accuracy in simulating canopy cover, biomass and grain yield. CRM, NRMSE, d and R2 in Darab were 0.03, 0.22, 96 percent and 92 percent for canopy cover, -0.10, 0.24, 92 prcent and 92 percent for biomass, and - 0.03, 0.06, 80 percent and 82 percent for grain yield, respectively. In Zarghan, these values were 0.06, 0.25, 91 percent and 89 percent for canopy cover, -0.08, 0.24, 91 percent and 87 percent for biomass and -0.02, 0.11, 71 persent and 86 percent for grain yield, respectively. Model application in different scenarios showed that the maximum delay in planting date is 5th November in Zarghan and 5th December in Darab. Grain yield was reduced to 3, 17 and 28 percent in 25 percent irrigation reduction and 15, 27 and 45 in 50 percent irrigation reduction in wet, normal and dry years, respectively.

Increasing the losses of water delivery and distribution regarding recent drought events makes necessity to upgrade the irrigation and drainage networks operation with higher transmission and distribution efficiency further than before. Providing solutions to improve water delivery and distribution and evaluating them requires the assessments of the plans from technical and economic views. Therefore, the present study, by giving non-structural and automation options, examines the efficiency of them by assessing the water delivery and distribution function and using the engineering economics under the inflow fluctuations conditions. The main canal of the Roodasht Network, which suffered from inflow fluctuations, was selected as a case study. The results of the simulation carried out by the ICSS hydrodynamic model, showed that the second non-structural strategies were efficient to improve the water delivery to Off-Takes by maximum 22% improvement of adequacy index relative to the present main canal operation. The automation method, by overcoming inflow fluctuations, supplied all the requirements of the crop areas and enhanced the adequacy index by a maximum of 85% than the current operation. Economically evaluation in the short-term of five years and long-term of ten years indicated that the automation method was more generate revenue than other methods. But the second non-structural option could produce a maximum profit in the standard scenario in the short and long periods 568 and 1446 billion Toman, respectively.

Saltwater intrusion is in the bottom of aquifer with gradually horizontal and vertical moving shortcoming of the most important quality issue especially in desert area. In this study the 3-D simulation of saltwater intrusion carried out by MODFLOW, MT3D and SEAWAT models. The results of flow modelling show that the decreasing in water table has been continued, in order to the hydraulic gradient in bottom of aquifer is reversed. . Considering the trend of groundwater direction indicated a huge volume of saltwater with high concentration moved to the aquifer. For 3-D simulation of quality flow MT3D model have been used. The results of this study show that the chloride concentration considerably increased due to 7000 ppm in the bottom of aquifer. Moreover, the saltwater intrusion moved about 100 meters to the aquifer in interface area. Consequently, the prediction of saltwater intrusion reach to 400 meters in near future.

One of the most important limitation factors the production of medicinal crops is water deficit and water stress in arid and semiarid regions of the world. Therefore, in this study, the medicinal crop Isabgol was selected as one of the valuable medicinal plants. The purpose of this study was to increase water use efficiency in Isabgol. Research carried out as a factorial experiment in a randomized complete block design with four replications. The treatments were A200 superabsorbent polymer at one level (125 kg ha-1) and zeolite at one level (2.08 gr/ kg soil) and control plot without adding soil amendments and 3 levels of water stress including 50, 75 and 100 The percentages water requirement. The measured factors included morphological traits (germination percentage, leaf area, dry matter weight, number of spikes per plant), biological traits (seed weight per plot, 1000 seed weight and mucilage) and water use efficiency. The results showed that treatments had significant effect on morphological and biological traits and grain water use efficiency. The best results were obtained for the morphological traits in the substrate containing superabsorbent polymer at 12.75 gr. The best results were observed for biological traits of 12.89 kernel weight and WUE 11.76 kg / m3 in zeolite bed.

Longitudinal dispersion coefficient (LDC) is a key element in pollutant transport modeling in streams. The most important factor affecting dispersion coefficient is the hydrodynamic flow. Due to the variability of hydraulic and geometrical parameters of rivers, the dispersion coefficient is a function of time and place, therefore precise calculation in such conditions is difficult and almost impossible. Many researchers over the years have provided numerous relationships to estimate dispersion coefficients, which all of them are based on average hydraulic and geometric parameters, but none of them have acceptable accuracy. Therefore, according to the uncertainty in estimating the dispersion coefficient, this question is proposed, “can we -in some cases- neglect the accurate estimation of the longitudinal dispersion coefficient? “The aim of the present study is to investigate the importance of dispersion coefficient at different places and times in rivers in non-uniform and unsteady flow. To validate the proposed method, it is performed for a hypothetical river with two different input pollution time patterns as well as for a real river (Karun River) with a hypothetical and real input pollution intensity function. The results of this study show that accurate estimation of dispersion coefficient is necessary only in some time and place ranges of the river and in most cases precise calculation is not necessary throughout the river and under these conditions if the dispersion coefficient is estimated with high error, it will have little effect on concentration distribution calculations and cause little error.