جستجوی مقالات مرتبط با کلیدواژه "توس" در نشریات گروه "جنگلداری"

Accumulation of secondary metabolites in plants is part of the defensive responses to pathogenic attacks that inducers induce and activate. Plant tissue and cell culture is widely used as a sustainable method for the study of plant secondary metabolites. Betulinic acid is one of the most important anti-cancer and anti-AIDS metabolites, the main source of which is birch (Betula pendula Roth). Due to the extinction of these trees in Iran, it is necessary to replace modern methods of cell and tissue culture instead of skin extraction. The present study has been conducted in the same direction and with the aim of increasing the amount of effective substance produced.

Birch inner skin Explants were cultured in NT+ (2.5 mlg.l) 2-4,D +(0.5 mlg.l) BAP with 3% sucrose and 0.8% agar and callogenesis was done. Sub cultures were performed once a month and The 8-month-old cells were exposed to a magnetic field. Birch cells were treated in Suspension culture (About 1 g of soft and white callus in 30 ml of NT culture medium with the above-mentioned hormonal compounds without agar) by static magnetic field with an intensity of 30 mT and on days 8-11 after sub culture, 4 hours a day. Then cell viability, growth rate, betulinic acid and antioxidant properties in cells treated with magnetic field were measured and compared with untreated cells.

The results of this study showed that growth rate, betulinic acid and antioxidant properties in treated cells increased compared to control. But, cell viability was not affected by the magnetic field. However, the amount of magnetic input did not cause cell death or death. In treated cultures, total betulinic acid production (18/51 g/l) was 2.5 times higher than control cultures (7/28 g/l) and in treated cultures the ratio of antioxidant properties (40/09 %) was 2.8 times higher than control cultures (14/2 %) and in treated cultures the ratio of growth (0/12 %) was 1.2 times higher than control cultures (0.09).

Plant cells affected by magnetic field can have unpredictable responses due to various factors including species, magnetic field strength and duration of exposure. In this study, the magnetic field, like other inducers or elicitors, induced secondary metabolism in the cells by triggering the message chain through oxidative stress, and increased the production of secondary metabolites in birch cells compared to control samples. It can also be said the electromagnetic field as an artificial stress caused the cells to react and increase the growth and production of active substances. This elicitor can increase the medicinal properties of birch by increasing the amount of betulinic acid and antioxidant capacity.

The aim of this study was to investigate the possibility of increasing the germination traits (germination and rate percentage) and vegetation characteristics of 3-month-old seedlings of Betula pendula (plumule and radicle length, collar diameter, fresh and dry weight of root, leaf area) by applying nano-priming and magnetic field. Seeds were collected from the Siah- Marzkouh area, 18 km from Gorgan-Golestan, Iran and after disinfection they were primed (soaked)  in a 1% solution of nano-chitin, nano-chitosan and nano-cellulose, and then sown. Magnetic treatment was applied to the seeds at three levels of 20, 30 and 40 mT at 1, 10 and 20 minutes and were sown immediately. A number of seeds were primed with all 3 nanomaterials after being exposed to the magnetic field (with the previous dose and time) and then planted. The results showed that among all the applied treatments, 1 min magnetism in 30 mT and then 2 hour seed priming with 1% solution of nanocellulose, were the best, In a way that increased the germination percentage (1.58 times), germination rate (1.9 times), number of leaves (1.2 times), leaf area (1.84 times) and root length (1.4 times) compared to the control (no treatment). The 20-minute magnetic treatment of seeds at 30 mT intensity and then the two-hour seed priming with 1% nanocellulose gave similar results. Two seed treatments (10 and 20 minute) in 30 mT (without nanopriming) are also recommended after these two treatments.

To identify diversity in natural populations of the genus Betula in Iran using macro morphological variability of leaves and seeds, a total of 1800 leaves and seeds from 90 trees in three sites of this material were measured. 25 macro morphological characters of leaves and seeds were used. Quantitative data were analyzed via one-way analysis of variance and nesting statistical design. Duncan's test was used for multiple comparisons of means. Cluster analysis was applied to compare and categorize the habitats and principal component analysis (PCA) determined the most important traits to separate three habitats. Multivariate analysis results indicate that leaf length, petiole length, the distance of the widest base of the leaf to leaf spot, the distance between the second and third veins, the average distance between the veins, petiole length, leaf length, leaf width in 0.9 part of the leaf length, number of teeth between the second and third veins and the tip of the leaf, seed length, length and width of seed wings had the most important role in the grouping of populations. The results of cluster analysis showed that different clusters contained different populations. The plasticity was used to determine that whether the environment were effective on the traits or not. The results showed that the traits that are recognized as the main attributes in the differentiation of these habitats, the environment does not affect them in terms of plasticity; and these traits are more influenced by genetics. Therefore, these traits can be used to identify the different populations of this genus in these three habitats as suitable attributes in completing the identification keys provided for the birch.

Different stomata types and their position with epidermal cells in genus Betula spp were studied at the three sites (Siahmarzkoo، Sangdeh and Shahrestanak)، by scanning light and electronic microscopy. Ten trees were selected with minimum 100 meters distance from each other. Significant differences in nested layout analysis were calculated between large and small stomata length، large stomata width، its area and no significant differences between small stomata width and densities in different populations. The highest and lowest stomata area related to Siahmarzkoo and Sangde. Correlation between stomata traits and geographical habitat characteristics showed that length، width and area of the stomata decrease by increasing height above sea level and will increase by increasing latitude and longitude. Detection analysis showed a 70 percent match between stomata characteristics and ecological conditions of the habitats. Two types of stomata including paracytic and anomocytic were identified in this genus with paracytic dominant. One similar type of stomata was recognized for three sites in terms of position of stomata in comparison with epidermal cells and in this type، stomata located over than epidermal cells.

In this research, effect of Using Hornbeam and Beech Branch Woods in Admixture with Birch Stem Wood on Their CMP Pulp Properties. Using percentage of branch woods, with 20% constant content for Birch stem wood, were 0, 16, 40, 56 and 80 in final mixture of hardwoods. The Results indicated that cooking time, to reach 85% yield and under same cooking condition, and also refining quantity, to reach 300 ml constant CSF freeness, were decreased with increasing portion branch woods (P<0.01). Moreover, despite a little decrease (P<0.01) in the optical and mechanical properties of the produced hard sheets by addition of branch wood in the hardwood stems wood, using 40% of branch wood in final mixture of the initial materials for making CMP pulp is recommended.