مجله پژوهش آب در کشاورزی
سال سی و پنجم شماره 3 (پاییز 1400)

This study was conducted to compare and monitor drip and surface irrigation systems for corn and wheat crops in three planting seasons from summer 2016 to spring 2018 in one of the agricultural research stations in Khuzestan, located in Ahvaz. The source of irrigation water was Karun River with salinity of 3 dS/m in Ahvaz section. This study was performed using randomized complete blocks design with three replications. The basis of blocking in corn cultivation was 2 and 4 days irrigation intervals, and in wheat cultivation, the distances between drip lines were 40, 60, and 75 cm. The results showed that the volume of water used in the drip system for corn and wheat was 24% and 32% lower than the surface irrigation system, respectively. Also, water productivity in the drip system was higher than surface irrigation system by 16% and 21%, for corn forage and grain, respectively, and by 35% for wheat. Wheat water productivity for different distances of drip lines was not significantly different. Therefore, in heavy-textured soils, drip irrigation lines at 75 cm spacing can be used for wheat cultivation. In soil monitoring analysis, the drip system reduced soil quality such that, after three planting seasons, the initial non-saline-sodic soil (ECe = 3.09dS / m, ESP = 6.18%) became saline (ECe = 7.63dS / m, ESP = 12.63%). Despite accumulation of salts at the periphery of the wetted soil under the drippers, the plants had a better growth and yield in the drip system than the surface irrigation, because of the high soil water potential around the roots and under the drippers, which reduced salt effects. The results of this study showed that if a drip system is used for the climate similar to the central and southern regions of Khuzestan, land drainage and leaching operations at the end of the growing season are necessary to protect the soil.

The purpose of this study was to investigate the effects of irrigation management on water requirement and crop coefficient of Hashemi and Kuhsar cultivars in the first crop. This experiment was carried out in Mahmoudabad District of Mazandaran Province in Iran in the form of factorial in a randomized complete block design, in two growing seasons of 2016-2018. The water requirements for the fields (from transplanting to harvest) and the crop coefficient of these two cultivars were studied in two systems of traditional flooding and system of rice intensification (SRI).  The results showed that, in the first crop, the two-year average water requirements of Kohsar and Hashemi in SRI were 534 and 556 mm and for the traditional flooding system 623 and 632 mm, respectively. The water required by the farm in traditional flooding decreased by 13.1% in the SRI. Based on reference evapotranspiration using pan evaporation method for the three stages of vegetative, reproductive, and maturing, crop coefficient values for the flooding system for Kuhsar were, respectively, 1.14, 1.29, and 0.92; and for Hashemi, they were 1.18, 1.32, and 0.92. According to the obtained results, SRI causes significant savings in paddy water consumption, therefore, it is suggested that, due to water shortage in the country, this method be used as one of the adaptation strategies in rice fields.

Lack of water resources, especially in the agricultural sector, is one of the common problems in sustainable development. For this purpose, the present study was conducted to investigate the effect of deficit drip irrigation method on yield, yield components, and water use efficiency of corn (single cross 704), in the crop year 2017-2018 in the research farm of College of Aburaihan, University of Tehran, in Pakdasht City. The experiment was performed as a randomized complete block with three levels of 100% (D1), 75% (D2) and 55% (D3) water requirement of corn in three replications. The highest biomass yield was observed at the level of 100%, and with the application of 75% and 55% deficit irrigation, crop yield decreased by 25% and 50%, respectively. Also, the highest grain yield was 14805 kg/ha in 100% treatment and the lowest was 10227 kg/ha in 55% level. The highest biomass water use efficiency was obtained for the treatment of 75% drip irrigation and was equal to 3.55 kg/m3 of water consumption. Therefore, it can be said that a drip irrigation system with 75% water requirement is the optimal system and its use is recommended.

One of the important problems in the agricultural sector of Iran is the low productivity of inputs, especially water. In this study, in addition to determining the physical and economic productivity of water, the factors affecting these productivities in the production of orange in Ghaemshahr County of Mazandaran Province were also investigated. For these purposes, three indexes of water use productivity including crop per drop (CPD), Gross benefit per drop (BPD), and net benefit per drop (NBPD) were used. Also, regression analysis was used to investigate the factors affecting water productivity. Necessary information was collected by completing 162 questionnaires from gardeners in the study area in 2018-19. Data analysis was also performed using Eviews7 software. The results of the analysis of water productivity indices showed that the average CPD index for orange was 6.9 kg /m3, BPD index was 47500 Rials and NBPD at three interest rates of 10%, 12%, and 15% was 29000, 28000, and 26600 Rials, respectively. Well’s discharge rate, days when wells were used, time spent for irrigation, the number of irrigations, age of trees, the distance between the trees, age of trees, cost of pesticide, and cost of fertilizer were the factors affecting water productivity. Among the mentioned variables, the variable of “time spent for irrigation” had the greatest effect on the physical water productivity, through the effect on the amount of irrigation water. Due to the negative effect of well discharge rate, the number of irrigations, and time spent on irrigation on the economic productivity of water, it is recommended to irrigate the orange trees in accordance with their needs and in a way that less water is applied.

The necessity of increasing economical productivity of agriculture and the increasing global demand for medicinal plants and considering the low water requirement of these plants have shifted the cropping pattern to their benefit. Water needs of Nigella sativa L., an important medicinal plant, was not known, therefore, we aimed to determine its water needs. (ETc) and crop coefficients (Kc) for different phenological stages in arid conditions of Birjand, in 2018. In order to conduct the research, three weighing lysimeters (with a diameter of 20 cm and a height of 16 cm) were used in three replications. Actual daily evapotranspiration was estimated by water balance in lysimeters and reference evapotranspiration was calculated based on 12 cm grass. The results showed that, in the initial stage, the rate of evapotranspiration was low, in the developmental stage it had an increasing trend, and after stabilization in the middle stage, with the onset of aging in the maturity stage of growth, the rate of evapotranspiration decreased. Actual and reference crop evapotranspiration was obtained as 670 mm and 1439 mm, respectively. The values of crop coefficients in the initial, development, middle, and final stages were obtained as 0.39, 0.53, 0.59, and 0.28, respectively. The general conclusion of the research is that by using the values of crop coefficients and water requirement, it is possible to cultivate this crop with maximum water productivity in the arid region of Birjand.

In order to investigate effects of water salinity on germination characteristics of quinoa (Chenopodium quinoa Willd), an experiment was conducted in a factorial and randomized complete blocks design with 10 treatments and three replication, in 2020. Salinity factor was considered at five levels (zero, 5, 10, 15 and 20 dS / m) and cultivars at two levels (Titicaca and Redcardina). Effects of salinity, cultivar, and their interaction were significant on germination percentage and its rate, length of shoot, root and seedling, vigor index, stem and root tolerance index. All characteristics were significantly reduced by salinity stress, with higher reduction in Redcardina than Titicaca. Salinity stress up to 5 dS/m had no significant effect on seed germination percentage of Titicaca, while in Redcardina, difference in germination percentage between distilled water (control) and salinity of 5 dS/m was significant. The highest germination percentage (100%) was obtained in treatment without salinity for both Titicaca and Redcardina. Germination percentage at salinity levels of 5, 10, 15 and 20 dS/m in Titicaca decreased by 1.4%, 4.9%, 14.3%, and 21%, and in Redcardina, by 2.6%, 6.6%, 18.3%, and 29.7% compared to the control. Stem length of cultivars at salinity levels of 5, 10, 15 and 20 dS/m compared to the control treatment were reduced by 6.8%, 14%, 27.6%, and 39.6% for Titicaca and 7.3%, 19.9%, 43.7% and 53.8% for Redcardina, respectively. This percentage reduction for root length of Titicaca was 2.1%, 12.6%, 32.6%, and 44.2% and for Redcardina was 6.4%, 21.2%, 38.2% and 57.9%. Salinity stress of 5, 10, 15 and 20 dS/m caused the dry weight of seedlings of Titicaca to decrease by 12.7%, 27.1%, 36.8% and 46.6% and in Redcardina by 11.4%, 27.8%, 45%, and 57.1%. Based on the results, Redcardina cultivar was more sensitive to salinity stress during germination than Titicaca.

Cucumber is one of the important greenhouse vegetables in Iran and the world. Cucumber is a warm and temperate season crop and is very sensitive to soil moisture regimes conditions. In order to model the effect of mixing soil with sawdust on the yield of greenhouse cucumber under different moisture regimes, an experiment was conducted in a completely randomized block design with three replications. Treatments included sawdust-free treatment (control) and a combination of 5%, 10%, 20%, and 40% sawdust and amount of water were considered at two levels of 45% and 65% of field capacity and a stress-free level. Using response surface method, the results showed that, based on the variables of sawdust percentage and moisture level, the best yield model is the second degree model with a regression coefficient of 0.85. Also, the effect of available moisture levels on yield was linear and, in contrast, the effect of sawdust percentage on yield was a quadratic function. Also, assuming the least available moisture and the lowest percentage of sawdust mixing (i.e. 13.7% of sawdust and 43.6% of field capacity), the highest yield was 86.6 tons/ha with a degree of desirability of 0.6. Also, assuming the least available moisture and change of sawdust between zero to 40 % (27.6% of sawdust and 47% of field capacity), the highest yield was 93.6 tons/ha, with a degree of desirability of 0.8. The results showed that, in any specific moisture regime, with increase in the amount of sawdust, root indices, except the main root length, had an increasing trend with decrease in available water. Besides, in each of the moisture regimes treatments, an increasing trend of yield was observed with increase in the amount of sawdust. Considering the nonlinear effect of changes in moisture regime and sawdust mixing rate on greenhouse cucumber yield, in order to achieve the best yield, sawdust mixing ratio should be determined for each soil.