Desert
Volume:26 Issue: 1, Winter - Spring 2021

Gypsiferous soils contain sufficient gypsum to influence soil physico-chemical, mineralogical, mechanical properties and geotechnical conditions and as a consequence, affect plant growth and crop production. So physico-chemical and mineralogical properties of 6 soil profiles located on the gypsiferous parent material with semi-arid climate in north of Urmia, West Azerbaijan province, Iran, were investigated. Based on standard methods, morphological, physico-chemical and mineralogical properties of these soils were determined. Soils with higher gypsum content had lighter color, lighter texture, lower values of organic carbon and cation exchange capacity and higher values of electrical conductivity. These parameters were reversely changed with decreasing gypsum content of soils. Semi-quantitative analysis of clay minerals indicated the presence of smectite, illite, chlorite, kaolinite and palygorskite were as major clay minerals with decreasing order from smectite to palygorskite. The origin of illite, chlorite and kaolinite were related to the inheritance from parent material. Smectite group of clay minerals has been resulted from three origins of inheritance from parent material, transformation of illite and palygorskite and neoformation, but the transformation and neoformation are the main pathways for its formation. Palygorskite has pedogenic origin and has been formed via neoformation. The comparison of clay mineralogy of soils with different gypsum values revealed the presence of higher smectites in soils with higher gypsum. Palygorskite was identified just in soils with higher gypsum. In soils with lower values of gypsum, illite and chlorite were the predominant clay minerals and palygorskite did not identified.

Increasing the salinity in the water and soil can negatively affect plant growth and development. Mycorrhizal fungi application is one of the ways to reduce the undesirable effect of salt stress on plants. An experiment was conducted in 2017 to assess the effect of salt stress on Nitraria schuberi, as a native Iranian plant in arid regions, inoculated with mycorrhizal fungi. Seedlings of this plant were treated under three different levels of NaCl in three stages. The stages including low salt concentrations (0, 20, 60, and 100 mM NaCl), medium salt concentrations (0, 40, 120, and 200 mM NaCl) and high salt concentrations (0, 80, 240, and 400 mM NaCl). Mycorrhizal treatment including two levels: non-inoculated (control) and mycorrhizal inoculated. Experimental designs were factorials (4×2 treatments) based on the completely randomized design with four replications. In this study, the content of chlorophyll, carotenoid, sugar, proline and Na, Mg, K, Fe and Ca were measured. The results indicated that with increasing salinity levels from the first (low) to third (high) stage, chlorophyll content was decreased while carotenoid, proline, and sugar were increased. The application of NaCl salinity led to a reduction in Fe and enhancement in Na. In the mycorrhizal plants, sugar content decreased but magnesium, calcium and potassium levels increased. Based on these findings it seems that Nitraria schuberi is a salt tolerant plant and mycorrhizal fungi can mitigate salinity stress in this plant. Therefore this plant could be applied in the urban landscape of arid and semi-arid regions.

In Iran, the drought is one of the costliest natural disasters, which has devastating consequences for the food security of agricultural households. Drought monitoring characteristics are important for better understanding of the drought phases in mitigation planning. Various satellite-based drought indices and systems have been developed and applied at both the regional and global scales. Recently the remotely sensed agricultural stress index system (ASIS) based on imagery from the Advanced Very High Resolution Radiometer (AVHRR-NOAA) and Meteorological Operational Satellite (METOP) by the Global Information and Early Warning System (GIEWS) of FAO developed. It shows considerable potential for drought monitoring at the global scale. Vegetation Health Index (VHI), start and end of the crop season (SOS-EOS) are the main inputs of ASI S. While the GIEWS models use the METOP-AVHRR images (1984 at present), in this study, an attempt has been made to retrieve key ASI inputs from the Moderate Resolution Imaging Spectroradiometer (MODIS) to evaluate the ability of the MODIS ASIS for characterizing agricultural drought severity and explore the impacts of drought on crop production during growing season. Comparing national and sub-national wheat and barley yields with the ASIS drought maps, demonstrated that the proposed approach could identify major historical droughts over the observed period (2002-2015) in Iran. We detected that the extreme severe drought occurred during the year 2007-2008 crop season, affecting approximately 64% of crop land.

The importance of Nitraria scoberi in many arid and semi-arid biodiversity projects is undeniable. Improving the vegetative properties of this plant is critical to the success of these designs. The present study was designed to achieve the best chemical, biological and mechanical priming treatments to improve the vegetative traits. Experiments were conducted in a completely randomized design in both cultivating tray and seedling bags. Chemical treatments included salicylicacid and gibberellicacid. Biological treatments included Azotobacter, Azospirillum, Bacillus, Flavobacterium and Pseudomonu. The 24 kHz wavelength ultrasonic device was used. In cultivating tray, all traits except for germination percent and shoot length were significantly different. In seedling bag environment, seed Vigor Index, root length, Seedling growth, root fresh weight, Shoot fresh weight, shoot dry weight, leaf fresh weight , leaf dry weight, shoot diameter and number of leaves and root to shoot ratio showed significant difference; There were no significant difference between germination percent, shoot length and root dry weight. Maximum seed vigor index, root length and leaf dry weight in both of environment, and fresh weight of root and shoot, root dry weight, fresh weight and number of leaves in cultivating tray and in seedling bag root to shoot ratio, shoot diameter and seedling growth in salicylic acid treatment 2000 ppm was seen. Azospirillum increased root, shoot and leaf fresh weight, leaf number and shoot dry weight in seedling bag.

Creating sustainable landscapes especially in arid climates is a significant challenge. To achieve sustainable landscapes, some strategies such as using native plants and soil mulches have been suggested. This study aimed to examine the quality and growth response of the native tall fescue (Festuca arundinacea Schreb.) compared with the corresponding commercial cultivar (Festuca arundinacea ‘Jaguar’) under different planting mulches in their planting and early growth stage in arid climate Mashhad city located in the northeast of Iran. Seeds of commercial cultivar and native species of Festuca arundinacea were sown in a sandy loam texture soil and four mulch treatments including vermicompost, leaf compost, cow manure and sand as control, were applied to cover the seeds. The result showed that the native species had greener color and narrower leaves compared to the commercial cultivar but its other NTEP (National Turfgrass Evaluation Program) traits including density, uniformity, establishment, softness of grass surface, quality after clipping, and total quality was lower than that in the commercial cultivar. Using vermicompost as the planting mulch (top dressing or cover mulch at the time of planting of the turfgrass) significantly improved all of the traits in the native species. Vermicompost increased the percentage of grass coverage, clipping dry weight, and the plant height and decreased the leaf width of plants and number and percentage of weeds. Utilizing native species of tall fescue with vermicompost as the planting mulch can promise as quality lawn as their commercial cultivar for native urban landscaping in Iran.

Over-capacity reduction is one of the major challenges facing humanity in the last century. To achieve sustainable development, there must be a tendency towards rational planning and utilization of resources based on their potential. Since agriculture has many environmental impacts on urban areas, evaluation of agricultural lands is necessary. The aim of this present study was to evaluate the ecological agriculture potential of Eshtehard country, Alborz Province. Therefore, the ecological potential of the study area was evaluated using ecological criteria and PROMETHEE II and Fuzzy AHP methods. To rank the selected criteria, to standardize the layers, and to assign the weights to each criterion, PROMETHEE II, Fuzzy and Fuzzy AHP methods were used respectively. The results showed that the lands with the first and four classes of ecological capability with 1.50% and 25.36% are included the smallest and highest percentage of the whole study areas, respectively. The results of our study showed the high efficiency of the combination of PROMETHEE II and Fuzzy-AHP in assessing the ecological potential of the area. In this study, the PROMETHEE II method is proposed independently of the number of land uses and criteria and it can be used with the changes for other areas.

Drought risk management requires drought monitoring which is usually carried out by applying different drought indices which are, effectively, continuous functions of precipitation and other meteorological data. However, these indices are estimated at specific locations, and the spatial distribution of drought must be calculated in the form of maps. Geostatistical and deterministic techniques make it possible to interpolate spatially-referenced data. These methods are able to estimate values for arbitrary locations in regions of interest. The current study applied five spatial interpolation methods (inverse distance weighted, global polynomial interpolation, local polynomial interpolation, radial basic function, and kriging [with 4 sub-types]) to extract maps of SPI at 60 rain-gauge stations in the Salt Lake Basin of Iran. Based on the root mean square error, mean absolute error, and mean bias error values of estimations made using sampled data from 1969 to 2009, RBF and kriging techniques were the best and most suitable methods for the spatial analysis of SPI in the study area. The current study applied five spatial interpolation methods (inverse distance weighted, global polynomial interpolation, local polynomial interpolation, radial basic function, and kriging [with 4 sub-types]) to extract maps of SPI at 60 rain-gauge stations in the Salt Lake Basin of Iran. Based on the root mean square error, mean absolute error, and mean bias error values of estimations made using sampled data from 1969 to 2009, RBF and kriging techniques were the best and most suitable methods for the spatial analysis of SPI in the study area.

A pot experiment was carried out to study the impacts of water stress upon physiological and biochemical properties as well as seed yield and components yield of Alyssum homolocarpum. The factors taken into consideration included water stress (80%), the capacity of field (60%) as well as field capacity (40%) within three stages of growth, stem elongation, flowering and seed setting. While water stress happening three stages of growth culminated in a reduction of plant height, component yield and seed yield, an increase in superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) activity was observed. Water stress increased content of proline, soluble sugar and malondialdehyde (MDA). The content of calcium (Ca) and magnesium (Mg) decreased in 40% and 60% field capacity at stem elongation stage compared to control. With increasing water stress mucilage percentage increased. In 40% field capacity at elongation stage Alyssum did not have seed yield. In this stress level, at flowering stage and seed setting, seed yield decreased by 85% and 68% compared to control, respectively. Result indicated the most sensitive growth stage to the water stress in Alyssum homalocarpum was stem elongation, Thus, It was suggested that this plant be irrigated at stem elongation to produce acceptable yield.

Dust storms are one of the most significant challenges in the Western Asia region in recent years and have intensified because of drought. Emission of dust in a scattered and especially heterogeneous manner has made it difficult to determine the exact effect, so modeling is one of the best possible ways to quantify dust emission. Moreover, to deal with this phenomenon, it is necessary to identify the main and influential factors and, by combining these factors, we can predict dust storms using models. The purpose of this study is to model the distribution and emission of dust in two stormy days on the 26th and 27th of January 2017 in the arid and the hyper-arid region of Mahshahr. For this purpose, coding of each meteorological parameter (section 2.2), dust input concentration parameters, and in MATLAB R2014 software have been made. Also, dust input concentration maps were prepared for the two stormy days in the study area in ARCGIS 9.3 software. Finally, the results were evaluated with WRF model outputs. The efficiency of the developed model was also evaluated based on the hourly data of the dust input concentration for two stormy days in the study area. The evaluation of the model shows the ability of this model to modeling the dust distribution in the study area with high intensity of dust emitted and high accuracy. The R correlation index for the period under study was 0.84, which indicates the high accuracy of the model.

Accurate information on the concentration of heavy metals in the soil is essential to manage soil contamination. The objective of this study was to investigate the contamination of soil and wheat plants with Ni, Cd, and Pb in the alluvial plain of Tigris River in southern Baghdad. A total of hundred surface soil samples (0-30 cm) and aerial parts of the wheat plant were taken in an area of ~100 km2 at an interval distance of 1000 meters. Heavy metals in air-dried soil samples and plant were extracted by the aqua regia solution and wet digestion method, respectively. The mean concentration of Cd in soil and wheat plant was 0.4 and 1.1 mg kg-1, respectively. The amount of plant-Cd was higher than the allowable standards of FAO and WHO. Mean Pb concentration in the soil of the study area was 14.5 mg kg-1. The concentration of Pb in the plant was less than the detection limit of the device. The mean concentration of Ni in the soil and plant was 214 and 17 mg kg-1, respectively, which was more than the allowable standards of FAO and WHO. The source of Ni is fine sediments transferred from eroded ultramafic rocks in the upper part of the river. A positive correlation between Pb and Cd in the soil indicates a similar origin. They were added to the soil by agricultural activities and vehicles. The results showed that the studied soils are at the beginning of the contamination with Cd and Pb, which needs to be considered to prevent more contamination.