فصلنامه گیاه و زیست بوم
پیاپی 37 (زمستان 1392)

The present experiment investigated Iranian hornbeam (Carpinus betulus L.) in 3 separate altitudes namely 300, 450 and 860 m above the sea level in Shast-Kalateh forests of Gorgan. Three standing trees were randomly selected in each altitude during the summer and 40 leaves were collected and dried from the middle part of the crown in each stand (10 leaves from each geographical directions). The morphological parameters of the leaves including: petiole length, leaf length, leaf wide, nerve number (right and left), teeth number (right and left), and leaf area were measured. Using statistical analyses, the relations between the measured leaf parameters in three altitude populations were investigated. The results indicated that leaf traits changed with an increase in the altitude. This trend in some traits (i.e. petiole length, leaf length, and teeth number) was a decreasing one and in some other traits (i.e. leaf width) an increasing one. It was also observed that the petiole length and leaf area were more significantly affected in comparison to the other leaf traits in the populations which were analyzed. Some leaf traits including leaf width and teeth number demonstrated a significant relation with the changes in the temperature and the amount of rain.

In this study, the forest areas of the North and North-West provinces were explored. Samples were collected from the roots, crowns, and trunks of the living trees. Samples (fungal fruiting body or the caps) were mainly of basidiomycetes and ascomycetes fungi types. The traits of each mushroom, its host, the location of the site were recorded. After the microscopic analysis of the cap, samples were investigated regarding the shape, color, thickness, the presence or absence of base, the presence or absence of upper and lower rings or both based on the type of tissue, the size, and other important characteristics. Some Species of forest medicinal fungi which according to previous research appear to have a significant impact on controlling various human diseases are introduced. It is hoped that this experiment provides a context for the cooperation of researchers and pharmacists. Some species are both edible and drug and hence cannot be directly applied. Generally speaking, the medicinal mushrooms such as Oudemansiella radicata are not edible and dangerous and should not be used as food.

Trees and shrubs have always played a significant role in water and soil conservation and the fulfillment of various needs of humans and the wildlife. Reports indicate that the existing distribution and variation in forest regions is decreasing everyday and in some case has resulted in the extinction of some species. One of the most significant strategies for preserving these rich and valuable areas is identification, collection, maintenance, and effective management of the genetic resources of the forests. As a part of the proposed plan for preserving the genetic resources of tree and shrub species in Tehran, the present study explores the condition and the biological diversity of these species. Samples were collected from different climatic regions through identification of a number of sites and referring to them during various vegetation periods. Over a five-year period, 79 species from 48 genera and 28 families were identified and recorded. The botanic and growth traits, the type of their application, and the amount of coverage in the dominant species were described. The seeds of different species were collected, identified, and sent to the plant-gene bank for conservation. During the research period a number of species including juniper, mastic, ash, elm, and shirkhesht were more specifically explored.

Kelussia odoratissima Mozaff. is one of the rangeland and medicinal plants native of Iran which is in danger of extinction. The present experiment was carried out in a completely randomized design with four replications in an attempt to investigate the effect of dormancy-breaking treatments on the germination and seedling growth of Kelussia odoratissima Mozaff. The treatments included: seed stratification (4°C for 2, 4, 8 and 10 weeks), gibberellic acid (250,500 and 1000 ppm solution), and the combination of seed stratification and gibberellic acid (500 ppm +4°C for 2, 4, 8 and 10 weeks). The results indicated that there was a significant difference between seed dormancy breaking treatments (P<0.01). The highest germination percentage was respectively obtained from 10- and 8-week treatments under 500 ppm + 4°C (86 and 88%). It was observed that the highest root (32mm) and shoot (24mm) length belonged to the 10-week treatment under 500 ppm +4°C.

Hazelnut (Corylus avellana) is native of Europe, Middle Asia, and Caucasus. Hazelnut tree cultivation has always been common and has witnessed an increase since the fourteenth century in Europe and gradually became popular in the Mediterranean countries. The Romans and Greeks used hazelnut for curing diseases and knew its nutritional values. The cultivation of this plant has been common in Iran from a long time. From botanical perspective, its origin dates back to the Neolithic geological age but the exact time of its cultivation is unknown. The present experiment explores the effect of the ethanol extract of the leaves and shatons of hazelnut on eight bacteria including: Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Micrococcus luteus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia, and Yersinia enterocolitica. The effect of extracts was compared with the impact of two antibiotics. Analyzing the antimicrobial effect of the ethanol extracts of shatons and leaves in various habitats indicated that there was a significant difference between the habitats. The extracts obtained from the leaves contained stronger antimicrobial traits in comparison to the shaton. The planted trees had greater antimicrobial qualities compared to the natural ones in the forest.

Zinc sulfate spraying of Thomson cultivars was carried out in the Research Orchard of Gorgan during the spring of 2010. The experiment was conducted in a randomized complete block factorial design including three levels of Zinc sulfate (2, 4 and 6 g/l) and control. The spraying was carried out in spring before the flower buds were open. The results indicated that the treatment of Zinc sulfate (4 g/l) has the greatest effect on the amount of fruit weight and fruit diameter on the tree. It also left the greatest impact on the concentration of Nitrogen, Phosphor, and Potassium in leaves in comparison to the control. Furthermore, there was a significantly positive correlation between the amount of Zn and Fe in Zinc sulfate spraying. A significant difference was observed in the amount of effective concentration of Zinc sulfate in all of the treatments. Zinc Sulfate generally increased the degree of yield.

Alstroemeria is considered as one of the ten most popular flowers in the world which has received great attention due to the variety of its colors and shapes. The leaves getting yellow and petal abscission are major problems which decrease the life span of this flower. The present experiment investigates the antibacterial and antifungal effects of nanoparticles of silver and Titanium in different concentrations (0, 1, 3, 5, and 10 ppm) and the natural essences of lavender, mint, thyme (0, 10, 25, 50, 100 ppm), and sucrose 1% as the preservative solution on Alstroemeria cv. Const coco flower. Traits such as vase life, relative fresh weight, solution uptake, total chlorophyll, petal Anthocyanin, appearance quality, total soluble in stem and petal, the percent of unopened buds, and the percent of dry matter in the flower were analyzed at the end of the vase life. The result indicated that the appearance quality, relative fresh weight, solution uptake, and vase life were the best treatments in all of the concentrations of lavender essence (5, 10, 50, and 100 ppm) and nano-silver (3 and 5 ppm) respectively with 19, 18.3, 19, 19, 18.83, and 18.33 days of vase life. The control had the most limited vase life with 11.5 days.

A large part of Iran is located in dry regions. Accordingly, various provinces are exposed to sand dunes during permanent and seasonal winds. Aran and Bidgol (in Kashan), which is located in the North of Isfahan province, is exposed to sand dunes during the spring winds blowing from the North-West and the summer winds blowing from the North-East. Due to the damages caused by the sands for the farmlands, residential areas, roads, ways, and infrastructures, the stabilization of sand dune in these regions appears to be essential. The present study introduces different types of petroleum mulch, mulching strategy, biological stabilization by means of adaptable plant species in the region, and a number of significant plants of this area. The results indicated that different plant species have covered about 1123678 hectares (73.64%) of the region. In addition, farmlands with 63107 hectares (4.14%), areas without vegetation with 310816 hectares (20.37%), stony lands with 27664 hectares (1.81%), and urbanized areas with 743 hectares (0.05%) spread across the region. The most significant plant types were identified and distinguished using floristic studies. The results indicated that using petroleum mulch creates a protective layer on sand dunes and temporarily stabilizes them. However, in the regions with better annual rainfalls, mulch coverage avoids the rain from penetrating into soil and increases its evaporation. Furthermore, petroleum mulch increases the thermal factor of the soil. In parts where the mulching is not carried out effectively or the mulch layer is very thin, sand hill erosion was observed. As a result, the best method for the stabilization of sand dune is soil maintenance and recovering its vegetation.

To investigate the allelopathic effects of six weed species (i.e., Conyza bonariensis, Acroptilon repens, Artemisia annua, Inula graveolense, Solanum nigrum, and Xanthium strumarium) on the germination and growth of wheat seedlings, an experiment was carried out on Triticum aestivum L. in the laboratory and greenhouse of the Gorgan University of Agricultural Sciences and Natural Resources in 2009 with a complete randomized design and three replications. The impact of the shoot extracts obtained from common plant species (i.e. Xanthium strmarium, Acroptilon repens and Conyza bonariensis) in the fields and rangeslands of Golestan province on the reduction of wheat seed germination under laboratory conditions was determined. The analyzed indices included: the percent of wheat seed germination at different times after the implantation, shoot dry weight, root dry weight in the seedlings at the end of each experiment. The results indicated that the shoot extracts of Xanthium strmarium, Acroptilon repens and Conyza bonariensis significantly reduced the wheat seed germination to 42%, 47%, and 20%, respectively, in comparison to the control. The allelopathic effects of the remaining and extracts in Acroptilon repens and Xanthium strmarium on germination and the growth of wheat seedlings were significant and resulted in a significant decrease in the percent of germination, root length, coleoptile length, and dry weight of shoot in wheat. Generally speaking, in comparison to shoot organs, wheat roots appeared more sensitive to the extracts. On the other hand, the shoot extracts were more phytotoxic compared to the root extracts. It was concluded that the extracts and remainings of three abovementioned plant types caused a decrease in the germination, root length, coleoptile length, and dry weight of root in the seedlings of wheat. It was also observed that the dry weight of root was more significantly affected. The results indicated that the extracts of Acroptilon repens have significant allelopathic effects which can be applied in the production of biological herbicides.