Background Poor physical and chemical properties of sand dune soil are the main constrains in afforestation of sand dune in desertified area. The aim of this study is to improve the physical and chemical properties of dune soil in Elrawakeeb Dry Land Station using organic wastes as a fertilizer source and amendments, for sustainable sand dune stabilization program. Salvadora persica L. seedlings were transplanted in a 2 m ´ 2 m plots and treated with: sawdust (SW), chicken manure (CH), chicken manure with sawdust (CH+ SW), sawdust with inorganic fertilizer (SW+ IF), sewage sludge (SS), sewage sludge with sawdust (SS+ SW), and control (C). The treatments were arranged in a randomized complete block design with four replicates. The soil chemical properties were determined from soil samples collected from the fixed sand dune (0–20 cm depth) in the second year after application.Results Application of organic amendments significantly (P=0.001) increased soil organic carbon by 224 %, available P by 139.9 %, total nitrogen by 142.9 %, and mineral nitrogen by 83.5 % and decreased soil pH by 5.6 %.Conclusions Incorporation of organic waste in desertified sandy dune soils increased its nutrient content and hence sustained biological fixation of sand dunes.

A two-dimensional numerical model, based on solution of the Reynolds-averaged navier-stokes equations with k-e and EASM (explicit algebraic stress) turbulence models, is presented to describe' the free surface water flow over bed topography (dune) in open channels.The model application indicates insufficiency of k-e turbulence model for simulation of flow over dunes (because of separation and streamline curvature). In this case, algebraic stress model that is economic method for calculating stresses can do better. Therefore, an explicit version of it (Wallin and Johanson 2000) is used All of the differential equations are solved with a finite volume method in a nonstaggered grid. The geometric shape of sand dune is simulated by introducing a general non-orthogonal curvilinear coordinate system.The numerical results were compared with the available experimental data reported by Mierlo and Ruiter (1988) and general agreement was observed. Detailed calculations indicate improving prediction of turbulence characteristics and length of separation zone by EASM model.

Wind erosion is considered a major global environmental problem. Sands torms cause serious damages to municipal, industrial and agricultural areas. Mulch is one of the most common materials for soil stabilization, which mitigates wind erosion and dust formation. In this research different combinations of organic (waste press mud, beet vinasse dunder and compost) were used in combination with clay as a stabilizer. Sandy soil from the Dejgah plain, the Provice of Fars, was used as the erodible material. Experiments were carried out in a completely randomized desing (CRD) with 14 treatments (organic mulch type). The mulches were sprinkled on plots of 50×30×1 cm sand. The thickness and mechanical properties of the mulched layear, namely the: shear strength, penetration resistance, and wind erodibility of the treatments were measured. Based on the analysis of variance (ANOVA), the effects of mulch type on thickness, penetration resistance, and shear strength of surface soil were highly significant (p<0. 05). Based on comparison of means with the Duncan's multiple range test, the M1 treatment with 25g compost+100g vinasse+100g clay had the highest thickness, penetration resistance, shear strength and the lowest amount of wind erodibility. Due to the biodegradability and economic justification (lower operating cost than petroleum and polymeric mulches), the organic mulch was recognized as the best combination for stabilizing sandy soils.

Introduction: Gerbera is one of the most important cut flowers in the world and belongs to the Asteraceae family. Due to its diverse and adaptable species for growth with a wide range of climatic conditions, this flower has become a profitable cut flower for growers. Polyamines in plant tissues act as a potent factor in preventing the production of ethylene. Polyamines and ethylene have antagonistic effects (anti-aging and aging effects), so that the balance of these two hormonal groups in plants is very important for plant tissues. The balance between the two opposing regulators leads to a delay or acceleration in the aging process. Mycorrhizal fungi can be useful in hydroponic greenhouse systems, which increase the amount of CO2 in greenhouses by increasing photosynthesis in plants, as well as CO2 emissions in the control environment, which both optimally manage the environment and increase the yield and quality of plant products. Due to the economic importance of cut flowers, it seems necessary to provide treatments (such as the use of putrescine and mycorrhiza) to increase the quality and longevity of this plant. Materials and Methods: This study was conducted in the research and production greenhouses of Urmia University and the research laboratory of the Department of Horticultural Sciences of the Faculty of Agriculture in 2019-2020. This study was performed as a factorial experiment in a completely randomized design with three replications, each replication consistedd of three pots and each pot contained a plant. The factors of this experiment were Mycorrhizal fungi inoculation (with and without inoculation) during the transplanting process to the culture medium near the roots, and putrescine at four concentrations of 0 (control), 1, 2, and 4 mM, were applied two weeks after transplantation, every 15 day-interval for three months. In order to investigate the effects of putrescine and mycorrhizal fungi on some morphological and physiological characteristics of plants, two weeks after the end of treatments, leaf sampling was performed to measure physiological characteristics. Effects of putrescine and mycorrhizal fungi were assayed in some morphological characteristics including leaf number, leaf length and leaf area, fresh and dry weight of leaves and some physiological parameters including chlorophyll index, chlorophyll content (a, b and total) and soluble sugar as well as vase life and petal’s anthocyanin during postharvest time. The SAS software version 9. 1 was used to analyze the variance and compare the mean of the studied traits. Comparison of means was performed using the Tukey’s range test method at a probability level of 1 and 5%. Excel (2016) software was also used to draw the graph. Results and Discussion: According to the comparison of means, putrescine, along with mycorrhizal fungi, increased the number of leaves, leaf area, and the fresh and dry weight of the leaves as well as chlorophyll index, chlorophyll a, b and total and carotenoid content of leaves. In this study, inoculation with mycorrhiza reduced leaf length but increased leaf area resulted in that mycorrhiza could increase leaf blade because of increasing cytokinin in plant. Putrescine with mycorrhizal fungi, increased leaf growth, photosynthesis of plant and carbohydrates production. In the literatures, it is reported that, the vase life of cut flowers is a very important point in choosing them as great cut flowers. The results showed, putrescine and mycorrhiza had increased the vase life of gerbera flowers, therefore increased the quality of this plant. Putrescine and mycorrhiza also increased the amounts of anthocyanins in the petals, and by the sixth day, the highest levels of anthocyanins were observed in the petals. Probably, the reason for increasing the anthocyanins on the sixth day is the presence of carbohydrates stored in the flower, which due to the reduced respiration and carbohydrate consumption in this process. Conclusion: Based on the results of the present study, it can be concluded that putrescine, with mycorrhizae, improved growth characteristics as well as increasing the postharvest life and the quality of cut flowers of gerbera. It is also observed that among the different concentrations of putrescine, the concentration of 2 mM had the greatest effect on the growth and physiological parameters as well as vase life of gerbera.

Resistance to flow is an important and primary parameter in the determination of water surface elevation. A variety of bed forms, especially dunes, have a sensible effect on total roughness. Because of the complexity of bed form development, previous methods differ drastically from each other in predicting dune bed forms. In this paper, laboratory experiments were conducted to investigate the geometry of dunes in a sand-bed channel and its influence on total channel resistance. The experiments were performed in a flume in the hydraulic laboratory of Shiraz University using sand particles. Simple relations were sought for dune dimensions via some dimensional parameters, and previous methods were compared to each other in light of this new data.

AbstractIntroduction: Rivers are complex systems in which different chemical, biological, and physical processes occur in it. When the flow moves along the river, there is an exchange between the surface flow and the subsurface flow. The hyporheic zone is a saturation zone below the riverbed, which plays an important role in many biological and chemical processes. Residence time is the most important characteristic of the hyporheic zone. Because the chemical and biological reactions that occur inside the sediments depend on the time at which flow paths remain in the bed for a while and then return back to the surface flow. Hyporheic exchange is the mixing of surface and subsurface flow just beneath the river bed. Such exchanges can be caused by the presence of different bedforms in the river. Dunes are one type of river bed that can be observed in straight, meander, and braided rivers. The pressure gradient between the upstream and downstream of a dune leads to hyporheic exchanges. The wavelength, amplitude, and slope of the lee side and stoss side can affect the rate of exchanges. In the present study, the effect of the dune lee side slope at angles of 10, 20, and 30 degrees on the characteristic of the hyporheic zone (i.e., residence time, exchange flow, and hyporheic depth) has been investigated numerically.Methodology: The FLOW3D software is used for the numerical simulation of surface flow. The simulation domain consists of a flume with 2.7m length, 0.1m width, and 0.3m height. The model running time was 120 seconds for surface flow simulation, which, with the passing of this time, the flow in the channel becomes stable. The pressures along dunes are introduced as a Dirichlet boundary condition on top of the groundwater model, i.e., MODFLOW. Then, the effect of the dune lee side slope at angles of 10, 20, and 30 degrees on the characteristic of the hyporheic zone (i.e., residence time, exchange flow, and hyporheic depth) has been investigated.Results and Discussion: The results show that the maximum and minimum pressure occurred on the stoss side and the crest of the dune, respectively. By increasing the dune lee side slope, the distance between the maximum and minimum pressure is reduced, the depth of hyporheic exchange decreases, and the exchange rate and residence time increase. Also, for all three angles, with a constant ratio of the subsurface to surface flow, the depth of hyporheic exchange increases with the increase of the hydraulic conductivity to the dune length ratio (K/A). Increasing the velocity of the subsurface flow causes the subsurface flow to dominate the surface flow and the flow in the subsurface flow moves towards the surface flow. As a result, by increasing the ratio of subsurface flow velocity to surface flow velocity, the exchange flow increases, and the depth of hyporheic exchange decreases.Conclusion: The results show that as the lee side slope increases, the residence time, and exchange flow increase, and hyporheic depth decreases. Also, by increasing the hydraulic conductivity, the hyporheic exchange depth increases, but by increasing the subsurface flow velocity and the porous media thickness, the hyporheic exchange depth decreases.