مجله پژوهش آب در کشاورزی
سال سی و هشتم شماره 1 (بهار 1403)

Water, food, and energy are three essential sources for maintaining life and fostering socio-economic development, and they are inseparably interconnected. The aim of the present study was to examine the indicators of water and energy efficiency of major agricultural products, namely, wheat and rapeseed, in two different climates in Sari (temperate and humid) and Sharifabad (hot and semi-arid) plains in Iran. To investigate these indicators in wheat and rapeseed crops, data from the agricultural year 2021-22 were utilized. Initially, the number of samples was determined based on the Cochran formula. Then, sampling was done using a questionnaire designed by the authors. The questionnaires numbered 300, and the collected information included inputs and production quantities. The results showed that the average water physical efficiencies in Sari Plain for wheat and rapeseed crops were 1.13 and 0.67 kg/m3, while in Sharifabad Plain, it was 0.83 and 0.35 kg/m3, respectively. Furthermore, the results indicated that the highest level of input energy in Sari and Sharifabad plains for wheat was 80618 and 71072 MJ/ha, respectively. The results also showed that greenhouse gas emissions were higher in Sari than in Sharifabad, probably because of excessive use of fertilizer and pesticide in Sari. The highest greenhouse gas emissions in Sari for wheat were 2495 kg CO2/ha, and in Sharifabad, it was 2299 kg CO2/ha. Overall, the results indicated that crop performance in humid regions was higher than in dry and semi-dry regions, and this indicator depends on various parameters, including water consumption and agronomic management.

Today, the rising demand for water coupled with diminishing water reserves has led to increased conflicts among water users. This research was conducted using a cross-sectional survey method, focused on analyzing water conflicts among Taghar River users. The statistical population included 230 rice farmers utilizing Taghar river water in Choram County, Kohgiluyeh and Boyer-Ahmad Province, Iran. Following the sample size calculation table by Karjesi and Morgan, 140 rice farmers from this region were selected as the statistical sample using a random stratified sampling technique. A structured questionnaire was used as the data collection tool, validated by subject experts, and its reliability was confirmed through a pilot study and calculation of Cronbach''s alpha coefficient (α ≤ 0.70) and composite reliability. Data analysis was performed using SPSS26 and SmartPLS3 software. The research findings revealed the presence of interpersonal water conflicts among rice farmers as well as conflicts between farmers and water organizations in the region. The R2 coefficient indicated that the independent variables (behavioral intention and perceived behavioral control) explained over 57.10% of the variation in conflict behavior. Behavioral intention (β=0.480) and perceived behavioral control (β=0.311) had the most significant direct impact, while societal norms surrounding the conflict (β=0.190) and attitude towards the conflict (β=0.127) had the most substantial indirect influence on water conflict behavior among the farmers studied. The study recommends building trust and involving rice farmers in river water management through the establishment of water users’ associations, along with conducting educational workshops on negotiation techniques and conflict management to effectively address conflicts among them.

For an accurate irrigation schedule, the daily soil water depletion should be estimated during the crop growth period. Soil water depletion is dependent on daily evapotranspiration. In this research, daily evapotranspiration of S.C 704 maize was measured in mini-lysimeters. Estimation of daily evapotranspiration was done by continuous measurement of soil moisture. Leaves stomatal resistance was measured daily, by AP4 Porometer device. Soil water allowable depletion was determined in four growth stages of initial (C1), development (C2), mid (C3), and late (C4), based on the leaves stomatal resistance response. At each growth stage, when leaves stomatal resistance increased relative to the control crops, readily available water was ending and the time was right for new irrigation. The main variables included growth stage effect on crop evapotranspiration and water depletion coefficient, which was investigated in a completely randomized basic design, with three replications. Regression functions (models) were used for simulation of allowable soil water depletion coefficient (P) based on the daily evapotranspiration (ETc). The models were calibrated by daily data at initial and development stages, and were evaluated by daily data in mid and late stages. The FAO-56 linear model was compared with the models introduced in this research. The results showed that maize ETc (S.C 704) in initial, development, mid, and late stages was in the range of 1.5-4.5, 3.9 -7.1, 1.4 -7.5, and 0.2 -2.1 mm.d-1, respectively. The allowable soil water depletion in the mentioned stages was calculated as 0.45, 0.66, 0.61 and 0.7, respectively. Different sensitivity in crop growth stages caused readily available water limit not to be constant during growth period. The ETc increase caused a decrease in P, and decrease in ETc increased P. Linear, exponential, logarithmic, polynomial, power, and FAO-56 linear functions were investigated. Polynomial function with statistical indices of RMSE=0.00035, NRMSE=0.054, ME=0.0008, CRM=-0/000005, R2=0.999 and EF=0.999, was the optimal model in estimation of P coefficient. The reason for weak performance of FAO-56 model was the constant limit for readily available water and mean ETc rate in the growing season. Therefore, the FAO-56 model was modified. The research result was to estimate the soil water allowable depletion coefficient (by using ETc), without daily measurement of soil moisture. This method will be useful in irrigation scheduling, especially those with short intervals.

The present study aimed at investigating the productivity and energy indicators of rice, wheat, fodder corn, seed corn and citrus fruits in Tajan Plain during 2022-03. Sampling was done based on 300 designed questionnaires. The collected information included man-days, working hours of machinery, fuel consumption of machinery, application of nitrogen, phosphate, potassium fertilizers, application of various types of chemical pesticides, including herbicides (in L/ha), the amount of applied water (m3/ha), the amount of seeds (k/ha), and the crop yield (k/ha). Results showed that the highest amount of energy in the input energy sector for rice was (593256 mega Joules per hectare, (MJ/ha), output energy for fodder corn (141795 MJ/ha), net energy for fodder corn (110758.53 MJ/ha) and energy efficiency was also for fodder corn (1.1 kg/MJ). Also, it was found that in all the products, the four inputs of water consumption, nitrogen fertilizer, machinery and fuel had the highest amounts. Results of water showed that the highest productivity in the Tajan plain was related to fodder corn and citrus (6.3 and 5.3 kg/m3), and the lowest productivity was related to rice (0.5 kg/m3). Also, the productivity of wheat and grain corn was 2.6 and 1.8 kg/m3, respectively. In general, to increase the productivity of lands and products in terms of productivity and energy indicators, it is necessary to use plants with appropriate yield, highest level of productivity, and lowest level of input consumption. Among the researched products, fodder corn had more suitable conditions than other products for increasing the cultivated area, due to its great impact on ensuring food security and reducing the need for livestock and poultry consumption inputs.

In arid and semi-arid areas, due to the existence of areas with low quality of water and soil, identification of wood species tolerant to salinity is very important. Therefore, this research aimed to identify provenances of Populus euphratica Oliv tolerant to salinity in comparison with the native provenances of Yazd Province, using a split plot experiment based on randomized complete block design (RCBD). Variables included the main factor i.e. salinity at 4 levels, and the secondary factor of Populus euphratica Oliv provenances at 7 levels. The study was performed with 3 replications during 2023-2024 at Hosein Abad Station of the National Salinity Research Center. Irrigation water salinity levels included (2.8, 6, 10 and 14 dS/m) and the provenances included 1) Isfahan, 2) Manjil, 3) Yazd-1, 4) Yazd-2, 5) Garmsar, 6) Garekhlar, and 7) Kerman. The results showed that provenance and salinity level affected the morphological and physiological traits and the concentration of nutrient elements. All the studied provenances tolerated salinity level of 6 dS/m, but with increase in salinity, all the growth characteristics in some of the studied provenances decreased significantly. At 10 and 14 dS/m, total height, total diameter, breast-high diameter, and their increase during the growing season, necrosis percentage and relative water content of leaves in the provenances of Kerman, Manjil and Garmsar significantly decreased compared to the control trees. However, sodium content, sodium to potassium ratio and relative ion leakage of leaves increased significantly compared to the control. A significant decrease in the investigated growth traits was observed in Yazd 1 and Garekhlar provenances only at the salinity level of 14 dS/m compared to the control. These results indicate that the provenances of Yazd-1 and Garekhlar were able to tolerate salinity of 10 dS/m by maintaining its growth characteristics and increasing potassium uptake against sodium. After them, Yazd-2 and Isfahan provenances showed relatively good tolerance to salinity. On the other hand, Kerman, Garmsar and Manjil were recognized as the most sensitive provenances to salinity stress. To select the best provenance for salinity tolerance, it is recommended to study the quality of wood and yield in different locations.

Camelina is an oilseed plant that could produce proper yield in arid and semi-arid areas with low water consumption. To investigate camelina response (Sohail cv.) to application of different amounts of irrigation water, this study was conducted in 2022-23 in Khatam District, Yazd Province. Treatments included drip tape irrigating based on 100% (full irrigation as control), 75% and 50% of full irrigation. Results showed that the effect of irrigation treatments on biological yield, grain yield, harvest index, plant height and protein percentage of camelina was significant (p<0.05). However, by reducing the volume of irrigation water, biological yield decreased significantly, such that biological yield of 75% and 50% treatments decreased by, respectively, 18.3% and 46% compared to the control treatment. The highest grain yield (2373.3 kg ha-1) was obtained with the application of 2384 m3 ha-1 irrigation water (control). By reducing the amount of irrigation water by 75% and 50%, grain yield decreased by 31.4% and 40.0%, respectively. The harvest indices were 22.6%, 19.0% and 25.1% for 100%, 75%, and 50% treatments, respectively. The highest plant height was 90 cm for the control treatment. The water productivity ranged from 0.88 kg m-3 for 75% treatment to 1.04 kg m-3 for the full irrigation. The highest proline content was observed for the treatments of reducing the volume of irrigation water, in which the amount of proline increased by 1.4 times compared to the control treatment. The results showed that the amount of irrigation water required for camelina was lower compared to the common winter crops, especially in tape irrigation method. Therefore, this plant could be used as a low water-demanding for delayed planting in winter season.