فصلنامه گیاه و زیست بوم
پیاپی 31 (تابستان 1391)

Fundamental of all plans of agriculture, forestry, range management and watershed management and aquifer and so on is physiographic study and determination of land talent. Since land use diversity in the region and soil erosion and degradation are important and this study was conducted by satellite photos and topographical maps with 1:50000 scale. After loading maps by GIS software, physiographic units and harmonious. Unit then having analyzed information were determined the researcher obtained hypsometry, aspect, slope and finally land talent maps based on physiographic properties. The results of field and combination of maps showed that there are many land uses in region, which have not been conform by physiographical study especially with slope. Thus this is one of the important factors to soil erosion and nature resources degradations inadaptable using based on suitable slope category. This region elevation are more than 1700 meter and there wasn’t too much different height between plain and sloppy region in which good soil and potential for growth plants. With delete of stone land and difficult to pass this different height didn’t have any role and there has been monotones relatively climate in region. According to this factor, notonly but also different aspects height didn’t have any affect on land talent ability. Not only beight but also different aspects didn’t have any effect on land talent ability. According to degradation intensity of natural resources and soil erosion in region, we must pay attention to percent of slope because it was the most important factor for determinaing land talent. According to maps slope class, we must allocate land with 0-12% to irrigated and dry farming, land with 12-14% to range management and gardening under counter and land with more 40% to plant a tree and semi tree and to conservation region.

In order to study the genetic variability in populations of two species of Bromus tomentellus and Bromus inermis for yield, morphological and seedling characteristics, 18 populations were examined in the field and germinator during 2006-2008 in Tehran Iran. The data were collected for heading date, plant height, tiller number, panicle length, forage yield, seed yield, and seedling traits (seed germination, speed of germination, seedling length and vigor index). Results showed significant differences between two species for all of traits except seed germination percent The B.tomentellus populations had higher values for all of seed characteristics; in contrast, B.inermis had higher values for yield and morphological traits. Estimates of broad sense heritability were high for all of traits ranged from 0.42 to 0.99. Both seed and yield had positively correlated with heading date, plant height, tiller number and panicle length and negatively correlated with thousand seeds weight. Using principal components analysis, the first three components accounted for 82% of total variation. The first principal component indicated that, Forage yield and seed yield couple with late maturity and plant height were important traits. In the second component, germination traits and in third one the tiller density and panicle length were the most important traits for classification of genotypes. Using cluster analysis (Ward method) the 18 genotypes were classified correctly into two groups as belonged to the same species. The distributions of genotypes based on (PCA) analysis were in agreement with cluster analysis.

Dactylic glomerata is very palatabe and important for soil conservation and production. Since salinity is one of the abiotic stresses that reduce the plant growth and production, this study was conducted to determine effect of salinity stress on germination of Dactylic glomerata from two locations Karaj and Bijar respectively. This study was performed on factorial design based on block complete randomized design with 3 repeat and 5 salinity treatment including 0, 100, 200, 300 and 400 mMol Nacl. Thr result of statistical analyses showed that germination between 2 locations had significant difference (P<0/001). Germination between different treatment had significant difference (P<0/001). The effect of various salinity levels on seed germination rate, germination percentage, shoot and root length decreased as the salinity increased. Alometry index was maximum in salinity 100 and 0 mMol Nacl in Bijar and Karaj respectively. In total, seed of region Karaj showed more tolerant to salinity than the seed of region Bijar.

One of the goals of targets ecologist is to determine accurate, fast and low cost method to determine the yield of rangeland plants which are interesting for them and the lencwledge of the amount of vegetation changes. Measurement of vegetation cover is easy but measurement of yield in plants is difficult. The aim of this research is to determine the relationships between variables vegetation cover with dominated and important shrubs yeild in dry rangeland of Sorkhdeh of Damghan provice. First 30 individual of 3 species of Artemisia aucheri, Salsola dendroides and Salicornia herbacea with different size. Were selected therefore small and large diameter variables and height of species were calcutated. The present yield was measured by clipping and weighting method. Regression relationship was determined between the independent variables including height, canopy cover and volume shrubs and dependent variable including yield. Regression analysis showed that there ware significant line relationship between independent variables and dependent variables in all species. Result according to information of models and coefficient of determination showed that variables of vegetation cover of species of Salsola dendroides and Salicornia herbacea well can be estimated yield in species we can develop this model in the study area. But this model of information of Artemisia aucheri cannot be estimated yield in the study area.Therefore this models cannot be developed and suggested in the study area.

Halophyte plants are the main sources for feeding the livestock (goat, camel, and sheep) in saline regions. The problem of these regions can be solved by an appropriate management and planning on these plants. The aim of this research is to determine the nutritive value of Halocnemum strobilaceum, which is a halophyte species, in three phenological stages of vegetative stage, flowering, and seed ripening in three different provinces: Qom Yazd and Uremia. After sampling randomly, ADF, crude protein (CP), amount of ash, ether extract (EE), metabolic energy, dry matter digestibility, and humidity percent were determined in laboratory using standards methods. Factorial analysis was applied for statistical analysis. The results showed that all factors measured during different stages and in different provenances were significantly different. The results also showed that quality indices of H. strobilaceum were to the highest amount during the stage of flowering in the Qom province in terms of nutritional value. Crude fiber and ash increased with increasing growth stage. In general, considering that this species is grown in severe ecological conditions and has good nutritional values, it can be used for planning and sustainable development of saline regions.

Allelochemicals of bed species in critical regions of rangelands as Peganum harmala L. may probably have negative effects on germination and growth indexes of improving rangeland species. Considering different responses of some plants to this materials, this research was conducted in order to determine allelopathic potentiality of Peganum harmala L. on an improving rangeland species (Secale montanum). The effects of different proportion of powders mixed with fine sand in pot unit (in 5 levels as 0, 5, 10, 15 and 20%) of two parts (aerial and underground) and three phenological stages (vegetative, flowering and seeding) of Peganum harmala L. were investigated on speed germination, percentage germination, root length and stem length of Secale montanum in factorial design with 3 replication. Another experiment (with ecosystemic consider) was done for determinig the effects of natural habitate soil in rondom design with 3 replication. The results showed that allelopathic effects of vegatative and flowering stage allelochemicals on speed germination, percentage germination and stem length of Secale montanum were more than seeding stage and there was not any Significant difference between these two stage with regard to root length. The allelopathic effect of aerial parts was more than underground parts and the differences in allelopathic property of these parts were severe with increasing propertion powder. Because of negative response speed germination, in spite of other variables to habitate soil effects, we recommended autumn tilling of Secale montanum, in order to compensate delayed germination in regions with cool winter and unsuitable spring conditions.

The investigation of the qualification of pastures is one of the main goals in pasture analysis and evaluation. Also the knowedge of effective agents is very important. Since, nearly all pasture ecosystem components affec on qualification, and because of complexity and majority, it is impossible, to study all of this agents, so, in this study tow physical agents and plant covering among other affective agents. Were used there models have been formed the main models components including, producing forage, water, source and sensitiveness to erosion. this study using FAO model to set in the environment of geography information system (GIS) in aregion with 11781.22 h.c extent was used in this study. The results of pasture qualification model showed that among physical properties, gradient, the instance from water source, rock and soil sensitiveness and among plant covering properties, producing forage allowed extent for exploitation, pastures situation and tendency, have been role in determining pasture qualification. The most limiting agents in determining qualification of region pastures are large gradient, converting pastures to dry farms, low percentage of plant covering, and low produced forage.

Environmental factors have an important effect on the distribution of plant species which lead to their distribution in different habitates. Therefore, this study has been done for discovering the effect of microtopography factor and some of soil characteristics on the distribution of Frankenia hirsute. This region been has saline soil with low depth under ground water table and halophyte plants were grown in this area. In order to determine soil characteristics, sampling has been done in flowering stage, from depth of 0 to 30 cm of soil from three area including: under grazing of livestock, exclosure and adjacent area (without any Frankenia hirsuta). For the determination of microtopography. Statistical analysis and comparing of data, by the used of SPSS software, showed that there is significant differences among Ec (Electrical Conductivity), ESP (Exchangeable Sodium percentage) and SAR (Sodium Absorption Ratio) in the presence of this species and in areas without the presence of this species. So the distribution of this species had dependent to these 3 factors particularly saline soil. Statistical analysis and comparing of meam data,by means of t-test, showed that there was no significant differences between microtopography. Totaly, Frankenia hirsuta usually have the distribution in sites with more humidity and saline little.

Autecological studies which is concerned with the study of relationship between species with surrounding environment provide basic information for the management of rangeland ecosystems. The autecological study Capparis spinosa L. was carried out in Sistan region. After determining habitat of this species, edaphic and climatic features relevant habitat, plant root systems, procedures phenology, seed weight and number of buds on each base were determined. The results showed that these spccies have been in sites such as discrete Eastern and had been Western parts of the region. Soil habitat of this species sandy loam texture and sandy clay loam, pH 8 to 6/8, and soil salinity, 3/1 to 7/58 dS. The average plant canopy covered 9 to 5/17 percent in the respective habitat. These racing roots up to two meters deep were observed. Phenological stages of the study species showed that the growth of then started and early in flowering march pully plants June was observed. The seeds in the beginning and middle of the June and also middle of August were observed August. The number of buds on each base were 30 and the weight of thousand seeds was 4-2 gram. Due to high resistance against these adverse natural conditions such as extreme heat zone, low humidity and sand storms, can be used in revived and reformed program in Sistan plain pastures.