بیابان
سال:1378 | دوره:4 | شماره:2 |تعداد مقالات:9

Smirnovia iranica, a native valuable woody species from Fabaceae, is an adaptable plant of central sandy areas of Iran. On other hand, this species could be markedly considered from different view points of forage production, soil conservation and medicinal applications.The current research was carried out in Band-e-Rig of Kashan, Iran to evaluate Smirnovia iranica properties including crude protein (c.p), NDF, ADF, P, K, ME and DMD in different phonological stages in order to find its forage quality for livestock nutrition. The result of chemicals analysis indicates that there is a significant difference among different phonological stages of S.iranica in terms of its properties. As the plant age is increased, c.p, ME and DMD are decreased while NDF and ADF are increased. This leads to reduction of S.iranica forage quality, since there is not significant difference between flowering and growth stages in view point of their c.p, ME, DMD, NDF and ADF, also according to increase of P and K in flowering stage, it seems that this stage could be considered as favorable time for S.iranica utilization by livestock..

In order to evaluate cardinal temperatures and optimum thermal range of germination of three medicinal plants including Ajowan, Fennel and Dill an experiment was conducted in a Completely Randomized Design with three replications. Temperatures considered for this study were: 5, 10, 15, 20, 25, 30 and 35°C. Results indicated that temperature affected germination rate and percentage of these crops. Optimum thermal range for Ajowan and Fennel seeds were determined as 10-20 °C and 10°C for Dill. The basic optimum and maximum temperatures were 2.88, 20 and 38.35 for Ajowan, 3.86, 20 and 34.98 for Fennel and 5, 13 and 33.7 for Dill. In general, as it is expected, germination response of these crops to temperature was correlated with the nature of growth of these plants. At higher temperatures, Dill as a winter crop showed a lower germination percentage compared to Ajowan and Fennel.

An experiment was conducted to optimize consumption of Zinc and evaluate of Zinc effects on quantitative and qualitative traits of winter wheat under saline soil condition. It was done by three replications in randomized complete block design. The experiment had four treatments as Control without Zn, 40 Kg.ha-1 Zn as ZnSO4, 80 Kg.ha-1 Zn as ZnSO4 in soil and 120 Kg.ha-1 Zn as ZnSO4 in soil. Eleven parameters including quantitative parameters and qualitative ones were measured. The highest grain yield (4355 Kg.ha-1, and highest Zn concentration in seeds (39.1 mg.kg-1) obtained by using of 120 Kg.ha-1 Zn as ZnSo4 as soil application. Seed protein content was affected by use of Zinc and significantly increased. The fourth treatment had a significant difference in compare to first and second treatments but didn't a significant difference compared to third treatment. Results showed that protein content in seeds was affected by using of Zinc Sulfate and significantly increased. Use of Zinc Sulfate had not any effects on straw, ear per square meter, number of seed per ear and concentration of Fe, Mn and Cu in seeds. Totally, use of 80 Kg.ha-1 Zn as ZnSo4 in soil was recommended to obtain highest grain yield with high quality in saline condition.

Acid rain has been a big problem for urban area during recent decades. Acid rain comes from high concentration of air pollutant, including man made or artificial and natural, in the atmosphere. Mashhad, as the biggest religious town in Iran, has also been imposed with this problem. In this investigation the samples of rains during autumn 2002 and, spring 2003 are analyzed. The results showed that concentration of different ions (SO4-2, NO2- , NO3- and NH-4 is higher than normal. Using the concentration of ions and average precipitation in Mashhad, the amount of wet deposition acid was calculated.Based on this calculation, the rate of acid that comes to the ground due to the rainfall was more than 24 Kg ha-1. Unfortunately we haven't got any critical load map for our terrain of interest to estimate the hazard. Comparing the wet deposition amount in Mashhad and North Wales in the UK shows that the wet deposition of acids in Mashhad are nearly the same as Wales that is a very pollutant area in UK. If we assume that the amount of dry deposition is something like wet deposition we can get an idea about the amount acid that comes to the ground during each year. According to the results of this research, paying more attention to Mashhad environmental issues is recommended.

Land use change may influence many natural phenomena and ecological processes, including runoff, soil erosion, sedimentation and soil conditions. Decreasing of forest area in the North of Iran is one of the critical problems in recent years. The aims of this study are to detect land use changes between 1967 to 2002 using satellite images of Land Sat 7 ETM+ (2002), aerial photos and digital topographic maps (1967 and 1994) and to , investigate the effect of some physical and socio economical factors on land use dynamic.The forest maps of 1967 and 1994 were collected from 1:25000 digital maps in Micro Station and then Arc/View 3.2 software. The interpretation of the maps of other land uses was derived using aerial photos. ETM+ satellite data were used to generate land use map dated 2002. The images quality assessment and dereferencing were performed on images.Different suitable spectral transformations such as rationing, PCA, Tasseled Cap transformation and data fusion were' performed on the images in ENVI and IDRISI software. Image classification was done using supervised classification maximum likelihood and minimum distance classifier utilizing original and synthetic bands resulted from diverse spectral transformation and the forest area was separated from non forest area.Unsupervised classification was used to separate other types of land use. Change detection has shown that the forest area decreased between 1967 and 2002 by 2.99% from 7322.22 to 6947.23 ha. Also, the area with irrigated land farms have been increased to 202.01 ha (1.61%) and the dry land farming area decreased to 9.2%. Overlaying the map of land use change with roads and residential maps showed that by increasing the distance from roads and residential areas and villages, deforestation rate and conversion of forest to arable lands were reduced, but conversion of arable lands to released lands increased. Also, the most quantity of deforestation was observed in lower slope angle, but the dry land farming converted to release lands was observed in higher slope angle.

Meteorological stations usually contain some missing data for different reasons. There are several traditional methods for completing data, among them bivariate and multivariate linear and non-linear correlation analysis, double mass curve, ratio and difference methods, moving average and probability density functions are commonly used.In this paper a blended model comprising the bivariate exponential distribution and the first-order Markov chain is introduced for estimating of missing precipitation data. In this method, the day having the missing precipitation record is marked as either wet or dry using the first-order Markov chain or randomly generated numbers. If the Markov chain model marks the day as wet, then a bivariate exponential distribution is used for estimating the magnitude of the missing precipitation datum. Application of the model to the precipitation data from Tehran Mehrabad station shows a good correlation between the statistics of the predicted precipitation data with observed ones.