Desert
Volume:15 Issue: 2, Summer - Autumn 2011

For determination of grazing capacity, information of forage quality is essential which is influenced by various factors. The main objective of this research was investigation on effects of species, phenological stages, and life form on values of forage quality indices of six range species. Species were two grasses (Bromus tomentellus and Dactylis glomerata), two forbs (Ferula ovina and Coronilla varia) and two shrubs (Salsola rigida and Artemisia aucheri). Samples were collected from two highland ranges of Gachsar and Vard Avar. They were dried, grained and analyzed in Laboratory. The results showed that forage quality indices values including crude protein (CP), acid detergent fiber (ADF), dry matter digestibility (DMD) and metabolizable energy (ME) were significantly differed among species, phenological stages, and life forms (P<0.01). For all species CP, DMD, and Me decreased and ADF increased with plant growth development. Considering forage quality indices values among six species, C. varia had highest forage quality. Among life forms, forbs, higher forage quality obtained from forbs. In terms of growth stage, vegetative growth stage had better forage quality.

Present research was conducted with the aim of determination of significant effect of soil properties on natural regeneration of Haloxylon aphyllum and correlation coefficient and linear relation between soil variables and natural regeneration of Haloxylon aphyllum. Firstly, geomorphologic units were prepared in the areas under cultivation of Haloxylon aphyllum in Ardestan. Two cultivated lands in Heidarabad and, Shamsabad were selected for sampling. Then, random systematic sampling was carried out in each of these lands. For this propuse, Thirty quadrates to size 10 × 10 m were for sampling and offsprings resulted from regeneretion of planted Haloxylon aphyllum plants were counted and, further, samples were taken form the soil in some locations for me measurements on physical variables (clay, sand and silt percentages)and chemical variables (Electrical conductivity, acidity, organic carbon, nitrogen and exchangeable Sodium). Results form such studies indicated that soil natural regeneration is significantly different in two regions of Heidarabad and Shamsabad at 1% level. Among soil physical and chemical variables, silt percentage had the highest effect compared to other variables, and also, physical variable were appeared to be effective factors on natural regeneration. There was a linear relation and negative correlation between the percentages of clay, silt, Electrical conductivity (EC), organic carbon, nitrogen and exchangeable Sodium (Na) with natural regeneration. Besides, results indicated the existence of a stright linear relation between the percentage of sand and the level of natural regeneration.

In recent years, acquiring information of remote sensing data, especially satellite data has excessively increased and several methods are presented in order to improve the quality of remote sensing studies in earth sciences. It is possible to manage many projects and provide different types of thematic maps in a short period of time, and a low cost by utilizing satellite data and GIS method. Recent researches show that utilizing satellite data in studying natural phenomena can effectively help to reduce the time and cost at the same time maximize the precision. But, many users of these data face confusion at choosing suitable image for their subject and lack a special criterion for that end, Or else they merely take one or two criteria in to account and lack a comprehensive view in choosing the best image. Therefore, defining and analyzing criteria for correct and precise selection of satellite data, in accordance with case-study, is crucial. So, in this article, we investigate the image selection criteria, especially their role in minimizing time, cost and extracting useful data. On the basis of the results, prior to doing of the project, users of these data need to study selection criteria properly. After that, on the basis of these criteria and phenomena under study they should set out to choose sensor type, date of image acquisition, image type, and methods of information extraction. Therefore in research, different practical aspects of satellite images as well as criteria for selecting suitable images are investigated and subsequently information and suitable solutions are provided for users.

Rapeseed (Brassica napus L.) is a crop relatively tolerant to salt. The effect of different ratios of NaCl/KCl was studied in two cultivars (Hyola308 and Kristina) of Rapeseed in 2002. Canola seedlings were grown in Hoagland’s solutions, which were salinized by different ratios of NaCl/KCl. The treatments or KCl:NaCl ratios were 0:0 (control);10:10; 20:0 (Total Added Salt or TAS=20 mol.m-3), 0:75; 10:65; 20:55(TAS=75 mol.m-3); 0:150; 10:140; 20:130; (TAS=150 mol.m-3) in a randomized complete block design with three replications. Plants were harvested before flowering stage and data were collected for root and shoot characteristics. The results indicated that in both cultivars, the shoot dry weight was decreased with increasing NaCl concentration in nutrient solutions. Increasing the KCl concentration in the nutrient medium significantly (P<0.05) reduced the toxic effects of high concentration of NaCl in K20NaCl130 relative to KCl10NaCl140; KCl0, NaCl150 in Hyola308. Salinity increased Na and Cl and decreased K, Ca and Mg contents of roots. Maximum Na accumulation in root was in Kristina and the minimum K content was observed in Hyola308. These observations showed salinity tolerance in Kristina is associated to a restriction of Na absorption at the root level. Salinity decreased the partitioning coefficients of Na and K. Partitioning coefficient of Cl decreased up to TAS=75mol.m-3and then increased. Kristina accumulated more Cl in the oldest leaves and K content in youngest leaves than Hyola308 cultivars.

Three grass species, Agropyron desertorum (Agde) and Agropyron elongatum (Agel) and recently, Bromus tomentellus (Brto) are mainly used for range improvement as mixed seeding in semi-arid areas of Iran. Because there is little information about management of these grasses, this study was conducted at the Sisab Research Station in northern Iran to evaluate their responses to grazing management and annual precipitation. Four grazing management treatments were applied for three consecutive years, from 1999 to 2001: no grazing, and light (20-45% forage removal), moderate (45-65% forage removal) and heavy (65-80% forage removal) grazing by lambs and sheep. The fourth year was considered to be a rest from grazing. Data recorded up to fifth years from 1999-2003. The average herbage yield (HY) production across years of Agde (1357 kg/ha) and Agel (1250 kg/ha) was statistically similar, and higher than that of Brto (880 kg/ha). HY decreased with reduction in annual precipitation for all species, especially Agel. Plant number per unit area declined over the study period in all species. Three years of heavy grazing resulted in significant reduction in HY and/or plant number for Brto and Agde, but the rest year compensated for the negative effect of intensive grazing on dry matter production

Current research on effect of increasing concentrations (0 (control), 100, 200, 300, 400 and 500 mM) of different salts including NaCl and Na2SO4 on germination and initial growth phase of Halostachys caspica were studied. The experimental design was completely randomized design with three replications. Characters of percentage, speed and index of germination, seed healthy index, radicle, plumule and plant length were measured. For analyzing of results were used of ANOVA, Duncan test and parried T- test sample in SPSS software. It was compared with germination under control condition, the most of characters of NaCl salt were not affected by 100 mM NaCl but were affected significantly different by 100 mM Na2SO4 salt. The results showed that effect of same concentration NaCl and Na2SO4 on radicle, plumule and plant length are significantly different but on percentage, speed and index of germination and seed healthy index the different aren’t significantly. The results showed that germination percentage were severely inhibited by 500 mM NaCl but no affected severely by 500 mM Na2SO4. However, the results showed that Halostachys caspica in growth characters such as, radicle, plumule and plant length is more sensitive to Na2SO4 than NaCl salt but in germination characters such as percentage, peed and index of germination is more sensitive to NaCl than Na2SO4 salt. At least we can put Halostachys caspica chloridephyte and sulfatephyte group of halophytes.

The probable maximum precipitation (PMP) is the greatest depth of precipitation for a given duration that is physically possible over a given size storm area at a particular geographical location at a certain time of the year. In this study a physically based method was compared with a statistical procedure to calculate PMP in the southwest arid regions of Iran. In order to estimate PMP using a physically or meteorologically oriented method, such climatological elements as precipitation, dew point temperature, and wind speed were studied in seven synoptic stations in the region. Synoptic maps of appropriate time scales were also studied. Then widespread and severe storms with various durations were selected and Depth-Area-Duration (DAD) curves for all the selected storms extracted. Using the physical method, PMP estimations were obtained at different locations and then the results applied to areas of 1000, 5000 and 10,000 km2. PMP estimations were also obtained through statistical analysis of the series of annual maximum 24 hour precipitations. The result showed that the values obtained through statistical procedures are more than two times those of meteorological method, for all the stations. Comparison of estimates indicated that least difference between two methods belongs to Abadan and the most difference to Bushehr, the magnitude of PMP in physical method is 39.2 and 22.8 percent of statistical method, respectively. Thus using statistical method for an estimation of PMP in the region leads to unacceptable consequences for a construction of water structures.

Four rapeseed cultivars (Hayola 401, Hayola 308, RGS and Option) were evaluated for some physiological traits under stress (50 % field capacity (FC) and non-stress (irrigated) conditions. The factorial set of treatments was arranged within a randomized complete block design with three replications. The collected data were analyzed using path and factor analyses. These is results showed that based on correlation coefficient, path and factor analysis number of seeds per silique was the best criteria for rapeseed cultivar selection under non-stress conditions and silique length, number of seeds per silique and photosynthesis rate at flowering stage were the best criteria for selection and yield improvement under stress conditions. Our results also indicated that selection based on simple correlation may not be efficient. The results of this study may guide breeders to introduce suitable drought resistant rapeseed cultivars for arid regions.

This paper presents a survey on soil Pb concentration around Sepahanshahr town located in vicinity of Isfahan. Due to the lack of regulation and environmental education and awareness, Sepahanshahr is now a rapid growing residential area suffering from the considerable consequences of poorly regulated mining activities operating in its vicinity. The aim of this study is to explore the spatial structure of Pb distribution and to map Pb pollution using geostatistical techniques. 100 near-surface soil samples were collected and analyzed for Pb and some other related soil physical and chemical variables such as pH, organic matter content, electrical conductivity, clay, silt and sand contents. The variography results show a strong spatial dependency in Pb data due to the dilution effects of natural factors including atmospheric dispersion and precipitation. The almost same range values calculated for both Ln-transformed Pb data and sand content suggest presence of co-regionalization. Kriged Pb map shows a strong gradient of Pb concentration around the three mining sites activating in the area. The results of this study provide insight into identification of the extent and the spatial variability of Pb pollution in the mining sites and surrounding area.

The aim of this research was to study the relationships between presence of plant species and environmental factors in Garizat rangelands of Yazd province and providing their predictive habitat models. After delimitation of the study area, sampling was performed using randomized-systematic method. Accordingly, vegetation data including presence and cover percentage were determined in each quadrate. The topographic conditions were recorded in plot locations. Soil samples were taken at depths of 0-30 and 30-80 cm in each plot. The measured soil variables included texture, lime, saturation moisture, gypsum, acidity (pH), ECe and soluble inos (Na+, K+, Mg2+, Cl-, Co32-, HCo3- and So42-). Logistic regression technique was used to analyze the collected data. The results showed that the vegetation distribution is mainly related to soil characteristics such as texture, gravel, EC, gypsum, lime and OM. The presence of Artemisia sieberi- Zygophyllum eurypterum has relation with gravel, lime, available water and pH. Ephedra strobilaceae-Zygophyllum eurypterum has positive relation with gypsum. Rheum ribes-Artemisia sieberi has relation with clay and OM. Cornulaca monacantha has also relation with elevation above sea, gravel and gypsum. The presence of Seidlitzia rosmarinus has relation with lime. Electrical conductivity is the most factors effect on presence of Tamarix ramosissima.

Field experiment was conducted in 2008 at the Research Field of Agricultural College of Shiraz University, Shiraz, Iran to investigate the effects of urban waste compost (UWC), manure and chemical fertilizer on the initial growth of corn (Zea mays). Experimental design was split plot factorial with three replications. Main plots were assigned to nitrogen (N) fertilizer (0 and 200 kg N ha-1), and sub plots were factorial application of municipal waste compost (0, 25 and 50 t ha-1) and manure (0, 25 and 50 t ha-1) with all possible combinations. Results showed that increase in urban waste compost and manure increased corn dry matter, height, stem diameter, leaf area, leaf number, SPAD meter readings and leaf N. There was a close relationship between SPAD meter readings and leaf N (R2=0.84). Correlation and path analyses showed that leaf area and SPAD readings are major components which affect corn dry matter at initial growth stage. Results of the present study revealed that organic fertilizer can improve initial growth of corn similar to chemical fertilizer. It can be concluded that manure and compost can be effective nutrient sources for corn production and can be considered as potential alternatives to chemical N fertilizer.

Investigation of soil properties like Cation Exchange Capacity (CEC) plays important roles in study of environmental reaserches as the spatial and temporal variability of this property have been led to development of indirect methods in estimation of this soil characteristic. Pedotransfer functions (PTFs) provide an alternative by estimating soil parameters from more readily available soil data. 70 soil samples were collected from different horizons of 15 soil profiles located in the Ziaran region, Qazvin province, Iran. Then, multivariate regression and neural network model (feed-forward back propagation network) were employed to develop a pedotransfer function for predicting soil parameter using easily measurable characteristics of clay and organic carbon. The performance of the multivariate regression and neural network model was evaluated using a test data set. In order to evaluate the models, root mean square error (RMSE) was used. The value of RMSE and R2 derived by ANN model for CEC were 0.47 and 0.94 respectively, while these parameters for multivariate regression model were 0.65 and 0.88 respectively. Results showed that artificial neural network with seven neurons in hidden layer had better performance in predicting soil cation exchange capacity than multivariate regression.