Journal of Arid Biome
Year:2016 | Volume:6 | Issue:1 |Papers Count:8

The present study was designed to evaluate the pollution status of some heavy metals in waste sediments caused by iron ore processing in Bafgh desert area. After drilling 7 profiles and sampling from 0-150 cm depth of sediments, concentration of 14 heavy metals in 35 sediment samples were measured by ICP-OES. To determine the background of heavy metals in soil of control site, 25 samples from the profile with a depth of 2.5 meters (one sample per 10 centimeter) was prepared and the concentration was determined by ICP-OES. After testing data normality, PI, IPI and MCd indices were calculated for determining the amount of pollution and changes in the measured parameters. The results showed that PI amount for As, Co, Fe and V were 4.365, 9.254, 4.57 and 9.249. Also the results about IPI and Mcd showed that 100 percentages of samples were in moderate class of pollution. Overall As, Co, Fe and V are as important pollutant parameters in the waste sediment caused by iron ore processing in Bafgh desert area. In case of lack of appropriate modifying or Precautionary proceedings, it will lead to contamination of soil and water resources in the region. Moreover, the findings of this study revealed the status of pollution and identified potential sources of water and soil pollutants in waste sediment, It is guidance for future research in order to examine the possibility of their removal by phytoremediation method.

Water availability, especially in arid regiones, is one of the major constraints for achieving optimum growth yield. In recent years, several numbers of researches has been done with different methods on adapting plants to environmental stresses such as drought stress. In this experiment, two plant growth regulators named 24-epibrassinolide and Jasmonic acid was used to improve drought tolerance of pomegranates (Punica granatume L. cv. rabab). Treatments were three levels of irrigation included sufficient water (control), mild stress (75 % of field capacity) and moderate stress (50 % of field capacity) and 9 levels of hormones included control (water), 24-epibrassinolide (0.1 and 0.2 mg/l), jasmonic acid (1 and 2 mg/l) and their combinations. These treatments arranged in factorial experiment in the form of complete randomized block design with four replications. Plant growth regulators sprayed on the leave of fertile trees before flowering and after fruiting rapid growth. Results showed that many chemical and biochemical parameters of fruit affected by drought stress. Application of 24-epibrassinolide and Jasmunic acid growth regulators changed the amount of total phenols in peel and fruit juice. The amount of antioxidant activity in peel and fruit juice was also altered by the above mentioned plant regulators. Results also showed that application of 0.2 mg/lit of 24-epibrassinolide in combination with 2 mg/lit of jasmunic acid could ameliorate antioxidant activity in peel under control and drought stress conditions. Application of 2 mg/lit of Jasmunic acid ameliorated the activity of peroxidise enzyme in fruit juice severe drought stress. According to the results, application of Jasmunic acid, lonely, or in combination with 24- epibrassinolide could have a positive effect on antioxidant activity of pomegranate fruit under the mentioned concentrations.

Alfalfa (Medicago sativa L.) is the most important forage crap in the world and is widely cultivated especially, in arid and semi-arid regions. Because of it’s widely distribution, alfalfa has developed different morphological, physiological, and biochemical mechanisms across environmental stresses, especially drought. Thus, this experiment was conducted to determine catalase (CAT), ascorbate peroxidase (APX) and peroxidase (POX) activities, hydrogenperoxide, and malondialdehyde (MDA) contentsof roots and shoots of ten alfalfa cultivars (Qomi, Isfahani, Hamedani, Bami, Ordobadi, Gharayonje, Nikshahri, Yazdi, Baghdadi and Cody) under sixwater potential (0, -0.2, -0.4, -0.6, -0.8 and -1MP) during germination.Drought stress increased CAT, APX and POX activities, hydrogen peroxide, and MDA contents, in both root and shoot, however such alterations were cultivar-drought level-specific. According to the correlation between measured traits at drought condition, antioxidant enzymes activity in roots and shoots had negative and significant correlation with hydrogen peroxide and MDA contents of both root and shoot. Cultivars with higher enzyme activities had lower hydrogen peroxide and MDA contents (Qomi, Baghdadi, Nikshahri and Bami), while cultivars with lower enzyme activities and higher hydrogen peroxide and MDA content (Isfahani, Ordobadi and Hamedani), suggesting that tolerant cultivars may have retained sufficient water and had active enzymatic defense systems against oxidative injury, moreover, antioxidant enzymes activity can be used as biochemical indicator for drought tolerance in alfalfa cultivars.

Social capital is one of the important concepts in sociology that it is necessary for social correlation and resistant development. The subject of this study is investigation of correlation between social capital factors and participation of exploitation in range management plans Performance in each exploitation systems. Reference population in this study according to the grazing license, was divided to private exploitation, collective exploitation and conciliar exploitation. Based on stratified random sampling method and Cochran formula, the sample volumes 50 of Ranches were estimated. For data collection was used questioner and interview. That interviewed with 93 people of exploitations. Descriptions result showed that in this area 66% of stockholders used rangeland as collective exploitation, 20% as conciliar exploitation and 14% as private exploitation do exploit from rangelands. Appreciation result showed that there is significant differences between social capital among and participation of exploitation in range management plan Performance (P<0.05). Kruskal Wallis test showed that there is significant difference between social capital with rangeland exploitation systems in this area(P<0.05).Finally index of social capital in this area showed that private exploitation has the highest social capital for range management plan Performance. It seems that Amplification of social capital items between exploitation, increase cooperation of exploitation in participation of range management plans performance.

In recent years, Arizona cypress plantations located in East Isfahan are increasingly drying. Water deficit and frequent drought are allegedly considered as the main reasons. Nevertheless, the wilting trees are not evenly dispersed across the plantations, leading to existing associate factors. The present research Consider that the effect of soil chemo-physical characteristics on the wilting rate. Preliminary research work showed that the forest area studied can be classified on the basis of environmental stresses related to four separate regions. One area due to its proximity to population centers , the two , proximity to roads , the three, with a maximum distance from the areas with high stress potential and the due to the proximity to the industrial zone four were selected. In each plot, all trees, including health, are drying up, dried, and even recently cut trees were counted, as well as Soil samples were taken from each plot up to a depth of 30 cm and then analyzed in the laboratory. Soil texture, pH, electrical conductivity, sodium concentrations in treated, Concentrations of calcium, sodium adsorption ratio, cation exchange capacity, total nitrogen and phosphorus and Potassium absorbable parameters were measured. Wilting rate was increased significantly in more salty and more conductive soils. Soils made up of particles of all sizes were more resistant to drought. The results also showed that overuse chemical fertilizers decreased the trees’ survival in severe drought conditions.

Digital mapping is a suitable alternative method to the traditional methods. In this method, soil salinity correlated to the environmental variables and then soil salinity predicts in the other locations. At present research, based on the hypercube method, the locations of 73 soil samples selected and then sampled. Electrical conductivity was measured in the saturation paste of soil samples. Then using artificial neural network (ANN) the relationship between ground point data and environmental variables (terrain attributes and Landsat 8 image data) was calculated and applied to the other parts of area. Sensitivity analysis indicated some environmental variables had more influence on prediction ANN model including normalized difference vegetation index (39.51%), soil-adjusted vegetation index (27.60%) and slope (5.80%), respectively. Moreover, the cross-validation implied high performance of ANN model to predict soil salinity (R2=0.57 and RMSE=17.40 dS/m). Our results, overall, showed that remote sensing data and digital elevation model and ANN had acceptable performance to predict soil salinity and hence it is recommended the same methodology in the future.

This study aimed to investigate the tolerance to salinity of Calotropis seedlings inoculated with the bacterium Pseudomonas Putida was conducted under greenhouse conditions. Treatments, six levels salinity stress factor with sodium chloride salt (0, 5, 10, 15, 20 and 25 ds/m) and two level inoculation factor (control and bacterium) as a factorial experiment in a completely randomized design with three replications was designed. Result showed that salinity more than 15ds/m, noninoculation bacterium seedlings were dried. However, bacterium inoculated seedlings in 15 and 25ds/m salinity level respectively more than 50% and 38% their survival maintained. In non-salinity condition, height, root area, fresh and dry weight of seedling, respectively 2.59, 40.35, 38.05 and 31.89 percentage increase in the bacterium inoculated seedlings compared to non-inoculated was observed. In most salinity level until 15 ds/m of Inoculated seedlings, rate of photosynthesis and chlorophyll significantly increased as well as transpiration rate decreased. But electrolyte leakage did not any difference. So concentration of nitrogen, potassium and potassium to sodium of leaves bacterium seedlings compared to control were increased while sodium of leaves decreased. Overall, this research revealed that Seedlings inoculated to PGPB pseudomonas until moderate level of salinity specially 15 ds/m has provided most optimal performance and efficiency. Hence, using of this bacterium as a new biotechnologic approach could be suggested for Inoculation seedlings this species in reclamation of saline lands and production of its seedlings in nurseries with salty soils.

In order to evaluate drought stress effects on some agronomical and physiological traits of Iranian fenugreek landraces (20 genotypes from different parts of Iran), two experiments (one under normal and another under drought condition) carried out using randomized complete block design with 4 replications. Seventy different agronomical and physiological traits were noted during experimental period. Results showed significant differences between fenugreek landraces in all traits under drought stress condition, except in dry biomass weight, grain harvest index, individual plant grain yield and canopy temperature, under non stress condition there were significant differences between landraces in all traits, except in number of pod/ plant, number of seed /plant, dry biomass weight, canopy temperature, leaves cell membrane stability at flowering stage, leaf relative water content and relative turgour. Calculation of studied traits coefficient of variation percentage, showed that, dry biomass weight and grain yield were the most impressive traits with drought stress with 44.9% and 30.85% of coefficient of variation, respectively. Plant type and leaf relative water content traits had the lowest coefficient of variation (about zero). According to the results, using from dry biomass weight and grain yield traits recommended for screening and selection of fenugreek genotypes under drought stress conditions.