مجله پژوهش آب در کشاورزی
سال سی و ششم شماره 3 (پاییز 1401)

Estimation of crop water requirement and evapotranspiration by lysimeter is costly and time-consuming and could not be applied to larger field scale. Remote sensing technology can overcome this limitation. The goal of this research was to estimate alfalfa actual evapotranspiration using satellite imagery and compare it with the in-situ measurement by lysimeter. The study was carried out from 2017 to 2020 in the agricultural lands of Alborz and Charmahal and Bakhtiari provinces employing Surface Energy Balance Algorithm for Land (SEBAL) method. Lysimeter has been implemented under standard conditions. The cold pixels of each satellite image were extracted to estimate net alfalfa crop water requirement. In-situ net crop water requirement for Alborz and Charmahal and Bakhtiari provinces were obtained as 1383 and 1087 mm, respectively. The coefficients of determination (R2) were 73% and 76%, respectively, for the two studied provinces. The statistical analysis showed that there were small deviations from the mean values. The standard evapotranspiration measurements using lysimeter were higher than the satellite estimations. This technique can be useful for the estimation of crop water consumption since it is simple, cheap, fast, and can be used for large areas.

In order to evaluate the effects of deficit irrigation on the yield and water productivity of grain corn in the climatic conditions of Gorgan,an experiment was conducted using split plots in the form of a randomized complete block design in three replicates at the Araghi Mahaleh Research Station of Gorgan, in 2021. The main factor was irrigation treatments at four levels (100% (control), 75%, 50%, and 25% of corn water requirement) and was done based on soil sampling for moisture determination and use of drip irrigation by tape, and the secondary factor consisted of four corn varieties (SC703, SC704, ZP548, BK50). The results of the analysis of variance showed that the effect of irrigation factor was significant (p< 1%) on the examined traits, except the number of rows in the ear. The effect of cultivars on all traits (number of rows per ear, days until earing, plant height, number of seeds per row, weight of 1000 seeds, length of ear, dry weight of stem and leaves, dry weight of cob wood, grain yield, yield, water productivity, and leaf proline) was also significant (p< 1%). Additionally, interaction of deficit-irrigation and cultivars on the traits of the number of rows of seeds, weight of 1000 seeds and seed yield was significant. Comparing the averages showed that the highest seed yield (7722 kg/ha) was observed in the control treatment and the seed yield of the 75%, 50% and 25% treatments compared to the control was 6.8%, 52.4%, and 82% less, respectively. ZP548 hybrid had the highest seed yield (5576 kg/ha) and the highest amount of proline was obtained from the 25% water demand treatment (9.91 μmol/g). The highest water productivity was observed in the 75% treatment (1.07 kg/m3). Considering the large volume of water saving (2258 m3/ha) in this treatment, irrigation is recommended based on 75% of water requirement and cultivation of ZP548 variety in Gorgan region.

A part of the plants' water needs can be met by shallow groundwater with desirable quality. In this research, contribution of shallow and saline groundwater to evapotranspiration of rosemary plant was studied in a completely randomized factorial design with three replications and using drainage lysimeters with a diameter of 1.20 m, in 2017 and 2018. The applied treatments included groundwater with salinity levels of 1, 2 and 4 dS/m at a constant depth of 0.8 m. The results showed that the total water requirement of rosemary was 597 mm. From total water required by the plant, 312.6 mm (54%), 260.3 mm (44%), and 201.1 mm (34%) were supplied by shallow groundwater with qualities of 1, 2 and 4 dS/m, respectively. The daily groundwater contribution was 4.9, 3.9, and 3 mm by, respectively, treatments 1, 2, and 4 dS/m. The effects of groundwater salinity on the yield of rosemary plant parameters were significant at the level of 5%, which can be attributed to the tolerance of this plant to groundwater salinity. In addition, due to the rosemary plant use of groundwater with different qualities, some water from surface water can be saved and irrigated land can be expanded, with consequently higher crop production and more jobs for farmers.

This study aimed to evaluate the efficiency of wick irrigation system in greenhouse cultivation of tomato plant and compare it with drip irrigation. The experiment was performed as factorial with a completely randomized design (CRD) in the research greenhouse of Tarbiat Modares University in 2021. Irrigation treatments included five levels (drip irrigation and wick irrigation with diameters of 1, 3, 4, and 5 cm) and two soil combination ("cocopeat, soil, fertilizer, perlite" and "soil, sand, fertilizer"), in 3 replications. The lowest and highest water consumption during the growing season was observed in wick irrigation with a diameter of 1 cm (29.25 L/plant) and in drip irrigation and wicks with a diameter of 5 cm (36 and 37.5 L/plant), respectively. The results showed differences of 19% and 4% in water consumption between, respectively, wick irrigation with a diameter of 1 and 5 cm compared to drip irrigation. Also, the difference in water consumption between wick irrigation (minimum and maximum water consumption) of 1 and 5 cm diameters was 28%. The yield in "soil, sand, fertilizer" cultivation bed was increased by 59% compared to the "cocopeat, soil, fertilizer, perlite" cultivation bed and the maximum tomato yield (700gr/plant) was observed in the wick irrigation with a diameter of 3 cm. Water consumption index in "soil, sand, fertilizer" cultivation bed was decreased 21%, rather than "cocopeat, soil, fertilizer, perlite" cultivation bed and increased water productivity by 100%. In wick irrigation, since water is always available, the plant does not face water stress and these results indicate that the wick irrigation system improves plant growth and increases production of wet and dry matter and water productivity in tomato plant. Although economic analysis has not been done in this research, but more crop yield along with less water consumption in the wick irrigation system would have more income for the user and can be an acceptable reason for using this irrigation method.

Construction of drainage systems is inevitable in paddy fields to control the level of waterlogging during rice harvest and cultivation of the second crop. Finding the best design option of drainage is very important from the point of view of environmental and economic issues. This study was conducted with the aim of investigating the performance of open drains including pressure head and depletion flux in controlling the water level in the cultivation of rice plants and the second plant in paddy fields. In this regard, the performance of open drains during rice and the second crop growth period was simulated using HYDRUS-2D model. To calibrate and validate HYDRUS-2D model, the required information was collected from 130 hectares of paddy fields in Nodeh, Jirsar and Nupashan villages in Soumesara region, in 2019. Soil texture, bulk and specific density, porosity and infiltration rate were measured. Also, pressure head of water was measured monthly in the region by piezometers. After validation, different open drain design options (bottom width and depth of drain) were run in HYDRUS-2D and its results were compared. The simulation results showed that the HYDRUS-2D had a reasonable accuracy in simulating the changes in water pressure head. The statistical indexes including R2, RMSE, nRMSE and MAE in the calibration stage were 0.98, 4.39 cm, 1.6%, and 3.55 cm, respectively, and 0.98, 4.33 cm, 1.67%, and 3.37 cm in the validation stage, respectively. The results showed that the open drain with a depth and bottom width of, respectively, 200 and 170 cm had the best performance for controlling water table during rice and the second crop cultivation, with a discharge rate of 726440 and 169960 cm3 per unit of drain length, and the reaction coefficient of 0.293 and 0.583 per day, respectively.

Many problems are encountered in the implementation of new irrigation systems with government subsidy, and the issuance of licenses is not an exception to this rule. Therefore, the main goal of this research was to identify optimal solutions for the process of issuing permits for the implementation of these systems. The statistical population of the research consisted of the applicants who registered their application in the five selected provinces of Hamedan, Fars, Zanjan, Khorasan-Razavi, and Kermanshah during 2019-2021 (N1=150) and the corresponding experts working on licensing new irrigation systems (N2=100). The research method was focus group and in-depth structured interviews. According to the results, the most important problems in the licensing process included: failure to perform work in a suitable and integrated system, the differences in the process of carrying out the project in different provinces, lack of familiarity and insufficient initial justification for the applicants, strictness and delay in determining the assignment of inquiries, and existence of some redundant and eliminable steps during the process. Based on this, the most important proposed solutions are: carrying out all process steps in a smart and integrated system, providing consultation to the applicant at the stage of filing and justification by reviewing the applicant's documents and facilities, removing unnecessary items in the process, paying the subsidy dynamically, applying an intelligent monitoring system with active feedback for all stages and all actors in the plan, and determining the time frame for each action. Within the system, the most important authorities to solve these problems are the Ministry of Agricultural Jihad and Agricultural Jihad Organizations of the provinces; and the external responsible authorities are mainly Plan and Budget Organization, banks, and the agricultural engineering system.

To investigate the interaction of magnetic water and deficit irrigation on yield and yield components of marigold, a factorial experiment was conducted in a completely randomized design in the research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad, Iran, in 2019, using pot culture with 3 replications. Treatments included 4 irrigation levels (100%, 85%, 70%, and 55% of field capacity) and 2 types of water (normal water and magnetic water). The results showed that different levels of irrigation on all traits (except physical water productivity which was significant at a 5% level) were significant (P <0.01). Effects of magnetic water on the dry weight of lateral branches and flowers, number of flowers and physical water productivity were significant (at P <0.01); and on the dry weight of flowering stems and leaves, number of leaves and lateral branches were also significant (at P <0.05). The interaction effect of the studied treatments was significant (P <0.01) on the number of leaves; and on the dry weight of roots, flowers, and flowering stems (P <0.05). The highest dry weights of leaves and flowering stems, number of flowers, number of leaves and lateral branches, height and physical water productivity were in irrigation with 100% field capacity and were, respectively, 1.77 and 0.37 g/plant, 7 and 6, 18.4 cm and 0.186 kg/m3. Also, reducing irrigation water by 15%, 30%, and 45% reduced the number of flowers by 25.7%, 32.8%, and 54.3%; and the physical water productivity by 18.8%, 21.5%, and 24.2%, respectively. The highest dry weight of flowers, roots, and lateral branches were observed in magnetic water + irrigation with 100% field capacity, as 0.29, 0.5, and 0.74 g/plant, respectively. The results showed that using a magnetic field increased flower yield and water productivity of Marigold plants under water stress. In this study, the best treatment was 0.6 teslas magnetized water+ 100%FC. However, to apply these stresses at the field level, more research is needed.