Journal of Water Research in Agriculture
Year:2019 | Volume:33 | Issue:1 |Papers Count:12

Dry farming is an important method of crop production, particularly in semi-arid regions, where crop yield strongly depends on precipitation amount and its temporal variation during the growing season. Supplemental irrigation is a suitable practice for mitigating moisture stress and, consequently, improving crop yield in rainfed agriculture. This study was conducted to estimate the proper time of supplemental irrigation in rainfed land by measuring soil water content during growth period, in 2016-2017. A field experiment was conducted using two plowing directions (along the slope and on contour lines) in plots with 2 m × 5 m dimensions, in a rainfed farm with 10 % slope. Volumetric soil water content (SWC) was measured in root zone by a TDR set at 10-day interval during growth period, from November 2016 to June 2017. Based on the results, SWC in the plots plowed on contour lines was about 6 % higher than the plots plowed along slope, and this difference was statistically different (P< 0. 05). The mean readily available water (RAW) during growth period in the plots plowed on contour lines (6. 07 mm) was about 2. 5 times higher than the plots plowed along slope (2. 25 mm) and showed significant difference with it (P< 0. 05). The highest RAW was observed at stem elongation and the lowest value was found at grain germination, at which stage, about 6. 7 mm water deficit was observed in rainfed wheat. Thus, application of supplemental irrigation at this stage can efficiently prevent water stress and improve wheat grain yield in this semi-arid region.

This research was conducted to determine the production function of common bean and cowpea and evaluation of water use efficiency in Astaneh Ashrafiyeh, in 2016 and 2017. The present study was conducted as split plot in a randomized complete block design with 3 replications. Main treatments consisted of irrigation of 40%, 60%, 80%, and 100% of water requirement of the plant, and nitrogen treatments in sub plots consisting of no fertilizer, 30, 60, and 90 kg N ha-1 and two bean varieties (ordinary beans and cowpea). The results showed that the effects of irrigation and nitrogen fertilizer on seed yield and other agronomic traits were significant (P< 5%), in 2016 and 2017. Two-year average seed yield in 100% water requirement and 60 kg N ha-1treatments in common bean and cowpea cultivars were 3446 and 3646 kg ha-1, respectively. The highest water productivity in 2016 and 2017 was obtained for the interaction of cultivar and irrigation on seed yield, and was 0. 48 and 0. 47 kg m-3, respectively. Water use productivity of the interaction between nitrogen fertilizer and bean cultivars in 2016 and 2017 in 100% water requirement treatment and 30 and 60 kg N/ha was between 0. 42 and 0. 46 kg m-3. The results of the estimation of production function indicated that the seed yield increased with nitrogen fertilizer application up to 30 kg ha-1, but with gradual increase in nitrogen fertilizer, the yield decreased. Based on the present study, 100% water requirement for seed yield can be recommended for both bean cultivars, however, the amount of fertilizer should be 60 kg N/ha for common bean and 30 kg N/ha for Cowpea.

A wide range of Iranian agricultural lands is located in arid and semi-arid regions and, hence, crops face some drought stress. Therefore, sustained agricultural production is important in these circumstances. Azotobacter is a molecular-nitrogen-fixing bacterium, which promotes plant growth by various mechanisms and may provide drought resistance. Inoculation of crops with superior bacterial isolates compatible with dry areas may increase plant tolerance to drought stress. In this study, the effect of inoculation of native isolates of Azotobacter isolated from arid and semi-arid regions of Iran under drought stress conditions was investigated on the growth of maizesilage cultivar i. e. Single Cross 704, in greenhouse conditions. The experiment was conducted as a completely randomized block design (RCBD) with three replications including inoculations with 15 Azotobacter isolates, blank (no inoculation and no drought stress), control (no inoculation but with drought stress). In order to apply drought stress by weighing method, soil moisture content in the vegetative stage was allowed to drop to 40-50% of allowable moisture depletion, and at flowering stage to harvesting, a range of 50-60% was maintained. The results showed that drought stress significantly decreased shoot dry weight, plant height, and dry weight of corncob compared to non-stress control. Inoculation with Azc10 resulted in a significant increase in the shoot dry weight compared to the control. This isolate increased the shoot yield by about 20% compared to non-inoculated treatment under drought stress conditions.

In order to investigate the effects of interaction between sodium chloride-induced salinity and organic fertilizer, vermicompost, on the vegetative growth and some mineral nutrieants in fennel (Foeniculum vulgare), a factorial experiment as a randomized complete block design with three replicates was conducted in the research greenhouse of Yazd University. Experimental treatments consisted of salinity levels of control (non-salty), 40, 80, and 120 mM NaCl, vermicompost levels of 0 and 5 volume/volume percent (two volumetric mixtures of vermicompost and soil including 0: 100% and 5: 95%), and fennel landraces of Urmia, Mashhad, Shiraz, Boushehr, and Isfahan. Sampling of plants was carried out 5 weeks after planting. Results showed that salinity stress significantly decreased dry weight and the length of shoot, leaf area, dry weight of root, concentration of potassium, calcium, zinc, and molybdenum of shoot, and concentration of potassium and calcium in root. Under both stress and non-stress conditions, all of these traits were significanly increased with application of vermicompost. Concentration of sodium in root and shoot was also significantly increased under salinity stress, while it sharply decreased in the presence of vermicompost. Based on the results, among the investigated fennel landraces, Mashhad landrace was the most sensitive to salinity stress. Shiraz landrace is recommended for cultivation in non-stress, and salt-affected conditions, and also under vermicompost application. It seems that the use of vermicompost can reduce the adverse effects of salinity on fennel growth.

It is very important to estimate the actual water requirement of the plant for irrigation planning and hence effective water management in the field. The purpose of this study was to evaluate the conventional methods of estimating crop water demands and the actual water requirement of basil plant under field conditions. For this purpose, an experiment was carried out on three separate hectares, with three different methods of estimating basil water requirement, including the method of Standard Class A evaporation pan, the method of TethaProbe soil moisture set, and a proposed weighing micro-lysimeter method. Besides, the study compared four irrigation treatments including full irrigation (FI) and deficit irrigation at (DI 80%), (DI 60%), and (DI 40%) of water requirement for two consecutive years in 2017 and 2018. The results showed that the highest amount of basil evapotranspiration was measured at 11. 2 mm/day, 53 days after planting. Also, basil crop coefficient values at the initial stages, development, middle, and end of growth were 0. 63, 1. 08, 1. 12, and 0. 97 respectively, and the highest basil coefficient in the 25th of July was equal to 1. 26. The highest yield of fresh matter in the direct method of estimating water demand was obtained at 5998 and 5966 kg ha-1, respectively, in 2016 and 2017 in full irrigation. Also, the results of this study showed that the proposed lysimeter method improved the method of Class A pan and soil sampling by, respectively, 10% and 8% water consumption, and yields by 10% and 5%, respectively. Also, with this method, the maximum economic return was 4186 Rials per cubic meter of water.

This study aimed at establishing the effect of different irrigation intervals on current assimilation and yield of rice genotypes. This research was conducted in Khuzestan Province for two years (2014 and 2015) using four irrigation intervals (1, 3, 5, and 7 days) in the main plots and 12 rice genotypes in the sub-plots, with three replications. The combined analysis results showed that the main levels of irrigation interval, genotypes, and their interaction effect had a significant (P<. 01) effect on all attributes. The amount and contribution of current assimilation of the three-day interval with an average yield of 4586. 9 kg per hectare and 89. 3 percent share had the highest relative value. Moreover, considering the highly positive correlation of grain yield with amount and contribution of current assimilation that were, respectively, (R=0. 9**) and (R= 0. 5**), we could conclude that the main reason for the increase in rice grain yield in this irrigation treatment was due to the increase in current assimilation – related attributes and allocation of more photosynthesis products to the main plant source. Consequently, IR 81025-B-327-3 genotype in the 3-day interval, which had the highest current assimilation, had relatively high share and efficiency of current assimilation and the highest grain yield with the average of 6555. 1 kg per hectare. In general, the increased yield of rice genotypes with greater resistance to drought, especially regarding the three-day interval, can be attributed to the ability of leaf source to increase the considered attributes and the high volume of the tank in fully receiving the assimilated matter produced by processes connected to attributes associated with these properties.

Effects of different irrigation levels on yield, water consumption, water use efficiency, and agronomic characteristics of cotton-wheat crop rotation were examined in the temperate zone of Khorasan Razavi. The study was conducted in Gonabad Research Station, using split-split plots based on randomized complete block design with three replications, in 2015-2016. Three tillage methods (no-till, conventional tillage, and reduced tillage) were in the main plots, three residue managements (without residue, 30% of the residues and 60% residue) in sub plots, and three levels of irrigation water (50%, 75% and 100 percent of the water required according to the National Water Document) were in sub-sub plots. Parsi wheat cultivar was used for cultivation. The results showed that the highest (non-significant) grain yield of wheat was obtained from no-tillage and without residue treatment. It was determined that no tillage and direct cultivation resulted in increased wheat grain yield and could be recommended economically, since it would reduce production costs. However, keeping or removing plant residues did not have a significant effect on yield, although the positive effects of plant residues on the improvement of soil properties and, consequently, on the yield of crops in the medium to long term are evident. The highest wheat yield (6249 kg/ha) was obtained from no-tillage with 30% residue and 100% of the water requirement. The highest water use efficiency of wheat (1. 57 kg/m3) was obtained in no-tillage, without residue and 50% of the water requirement. The highest yield of wheat was recorded in the full irrigation (100%) treatment and was significantly different from other irrigation treatments (75%). By applying 50% of the water requirement, wheat yield decreased by 36. 3% and by applying 75% of the water requirement wheat yield dropped by 31. 5%. As a result, it is possible to save water consumed by wheat under a conservation agriculture system because water productivity increased in comparison with the conventional agricultural system.

In order to study the effect of salicylic acid on some growth and biochemical characteristics of lemon verbena (Lippia citrodora L. ) under salt stress, a pot experiment was conducted as factorial, based on completely randomized design, with four levels of water salinity (control, 50, 100, and 150 mM NaCl) and four levels of salicylic acid (SA) (0, 150, 300 and 450 mg/L, equivalent to 0, 1. 06, 2. 12, and 3. 2 mM, respectively). The results showed that interaction effects of salinity and salicylic acid on all of the studied traits were significant, except leaf dry weight, and fresh and dry weights of root. Based on the results, the highest amount of leaf fresh weight, fresh and dry weights of aerial parts, chlorophyll a and chlorophyll b and carotenoid contents were found in the treatment without salinity and application of 3. 2 mM SA. The highest amount of soluble carbohydrate was in the treatment without salinity and application of 2. 12 mM SA, the highest proline was in 100 mM NaCl and application of 3. 2 mM SA, and the highest total phenol was in 100 mM salinity and application of 2. 12 mM SA. Therefore, application of SA (especially at 3. 2 mM) under salinity stress (100 and 150 mM NaCl) mitigated the negative effects of this stress, increased morphological traits and photosynthetic pigments, and, conversely, decreased the amount of total phenol, soluble carbohydrates, and proline by reducing salinity stress.

For proper use of available water resources in agricultural sector, selection of suitable irrigation system is necessary to provide the crop water requirements. Correct choosing of irrigation system is an important step in optimal application of water and soil resources. Involvement of several influential factors in selection of appropriate irrigation system has made this a relatively complex issue. In this study, application of different irrigation systems were prioritized by climate, water, soil, field, irrigation efficiency, cultural, social and economic information using analytical network process method (ANP) in the Ajichay river basin. Based on the results of the selected criteria, water quantitative and qualitative, irrigation efficiency, and soil had the most effect on the best irrigation system selection with relative weights of 0. 222, 0. 221, and 0. 1539, respectively. Also, the results of the sub-criteria scores showed that the sum of water sub-criteria was the highest, with final score of 0. 26815, among the other sub-criteria scores. Finally, the results showed that, among surface irrigation systems, the basin system with a score of 0. 15544, among sprinkler systems, the classic system with score of 0. 10432, and among localized systems, trickle system with a score of 0. 12754 had priority over other systems.

The aim of this study was to determine the optimal cropping pattern in irrigation network of Qazvin plain with emphasis on deficit irrigation policy and reduction of fertilizers and chemical pesticides. For this purpose, the Positive Mathematical Programming approach (PMP) and Maximum Entropy Technique (ME) were used. The results of the first option (5% deficit irrigation in wheat, barley, grain corn, fodder maize and Sugar beet at the ripening stage, and 5% deficit irrigation in the vegetative growth stage for alfalfa simultaneously with5% reduction in fertilizers and chemical pesticides) showed that sugar beet, alfalfa, grain corn and fodder maize were be desirable for cropping pattern due to their high economical profit in compared to wheat and barley. Also, applying this policy leads to an increase in gross margin (4. 5%) and a reduction in water consumption (5. 1%) in the agricultural lands of the region. As a result of the implementation of the second scenario, the cropping pattern goes towards products that have a higher economic margin due to their lower irrigation water consumption. This scenario leads to 3. 6% increase in gross margin and 17. 2% reduction in water consumption. Other results of the research showed that due to the application of these policies in PMP, the sustainability indicators of water resources, fertilizers and chemical pesticides are less than the current values for the region's present cropping pattern. The calculated environmental index revealed that high consumption of water, fertilizer, and other chemical inputs are a barrier to achieve sustainable agriculture.

This research was conducted with the aim of studying the effect of interaction of water stress and different levels of zeolite on growth and yield characteristics of black cumin (Nigella sativa L)plant during cropping season of 2018. The study was based on completely randomized block design as split plots, with irrigation at two levels (I1 and I2: irrigation with 100% and 50% water requirement, respectively) and zeolite treatment at three levels (Z0: without Z1 and Z2: using potassium zeolite at 2 and 4 gr. kg-1soil, respectively), with three replications at Research Farm of Faculty of Agriculture, University of Birjand. Under the influence of interaction between zeolite and irrigation management, the highest plant height was 16. 88 cm, and weight of fresh and dry yield and 1000-seed were, respectively, 11. 96, 9. 33, and 13. 19 g. Also the number of capsules per plant and seeds per capsules were, respectively, 10. 11 and 52. 44. The maximum grain yield was 874. 77 kg. ha-1 and water use efficiency (WUE) was 0. 135 kg. m-3, respectively. The lowest values for the corresponding parameters were 13. 13 cm, 7. 4, 5. 05, and 11. 95 g, respectively, and 8. 33 and 44. 44 for the number of capsules per plant and seeds per capsule, yield of 748 kg. ha-1 and WUE of 0. 118 kg. m-3, . Water stress led to a decrease in the characteristics of growth and yield of black cumin. Therefore, application of zeolite at high levels (15 tons per hectare), especially under full irrigation of the plant, could lead to maximum yield and characteristics of black cumin growth.

Climate change affects the hydrological processes through changes in temperature, precipitation, and other climate variables. One of the most important consequences of climate change is its impact on agricultural water consumption, which can seriously address water resources management. The purpose of this study was to investigate the effects of climate change on daily evapotranspirationin different climates across Iran. For this purpose, the minimum, and maximum temperature, as well as precipitation, and sunshine hours were simulated for the period 2016-2036 on the A1B, A2 and B1a scenarios using the HadCM3 general circulation model and weather generator (LARS-WG 5. 5) on daily time scale. The results indicated increase in temperature and evapotranspiration and decrease in precipitation in different climates. In another section of this study, by comparing the empirical equations, it was concluded that Hargreaves method with high R2, fair NS, and lower values of RMSE and MAE compared to other methods, can be an appropriate alternative for the FAO Penman-Monteith method on daily scale. For example, the results for Birjand station were R2 = 0. 59, NS = 0. 53, RMSE 6. 84 and MAE = 6. 01. Finally, Hargreaves-Samani and the Makkink methods had the least accuracy in estimating the reference evapotranspiration. Therefore, Hargreaves method can be selected as the best alternative method for estimating the reference evapotranspiration on a daily basis.