جستجوی مقالات مرتبط با کلیدواژه « کشت درون شیشه ای » در نشریات گروه « زراعت »

This study aimed to evaluate the effect of different types and concentrations of plant growth regulators in MS medium on callus formation and regeneration of different explants of medicinal plant Galega officinalis. To callus induction, leaf, root, hypocotyl, and stem nodes explants were cultured on MS medium containing different concentrations of 2,4-D (0.5, 1, 3, and 5 mg/l) in combination with BAP (0, 0.5, 1 and 3 mg/l) or Kin (0, 0.5, 1, and 3 mg/l). It was observed that 2,4-D in combination with Kin was very effective and in most of the used concentrations, it resulted in 100% callus induction. Among them the 5:0.5 mg/l concentration of 2,4-D:Kin in the nodal stem explant showed the highest callus growth with an average of 1450 mg fresh callus weight. In order to direct regeneration, leaf, cotyledon, and stem nodes were cultured in MS medium containing different concentrations of BAP and Kin in combination with NAA, while regeneration was observed only in the stem nodes. The highest regeneration rate was related to 0.25:0.1 mg/l in both BAP: NAA and Kin:NAA with an average of 93.33%. The highest amount of induced shoots (with an average of 2.86 shoots in each explant) and the highest shoot length (5.6 cm) were observed at 2:0.5 and 2:0.1 mg/l of BAP:NAA, respectively. The shoots obtained from the regeneration experiment were transferred to MS medium containing different levels of NAA and IAA for rooting. The results of mean comparisons showed that 0.25 or 0.5 mg/l of NAA or IAA resulted in the highest percentage of rooting with an average of about 90%. The highest number of roots was related to explants cultured in 0.25 mg/l of both NAA and IAA growth regulators (with an average of 4 roots per explant) and also, the highest root length was observed in explants cultured in 0.25 mg/l of IAA (with an average of 6.5 cm). At all, in this study, the most appropriate combination of plant growth regulators and explant for callus induction and direct regeneration of G. officinalis was introduced, which can be useful in future biotechnological studies of this medicinal plant.

The present study was conducted to reduce the effects of salinity stress on germination and initial growth stages of Thymus vulgaris as a medicinal plant using brassinosteroid (BR) under in vitro culture. Thyme seeds were exposed to different concentrations of salinity (0, 50, 100 and 200 mM) and BR (0.5, 1 and 3 µM), and then different germination and growth indices as well as some phytochemical properties of seedlings were measured. Results indicated that under salinity conditions, the highest germination percentage (95%) was observed at the lowest salt concentration (50 mM) and the highest BR concentration (3 µM). Applying differentBR concentrations improved root and shoot height.It also increased dry and fresh biomass of thyme seedlings in a way that at the same salinity conditions of 200 mM, root and stem length increased about 30.5% and 42.9%, respectively, in samples treated with 3 µM BR in coparison with the ones treated with 0.5 µM BR. The amount of proline and antioxidant enzymes, peroxidase (POD) and superoxide dismutase (SOD) significantly increased in the seedlings treated with the highest BR concentration in comparison with those treated with the lower concentrations, and the seedlings had lower membrane permeability (lipid peroxidation). The results of correlation coefficient showed that there was a negative correlation between cell membrane permeability (amount of malondialdehyde) and all measured biochemical and morphological traits related to seedling growth. According to the results of this study, it is suggested to apply BR during the sensitive stage of seed germination and early growth of garden thyme seedlings under water or soil salinity conditions.

Begonia is one of the most important ornamental plants around the world. Begonia species are grown for their attractive leaves and flowers in indoor and outdoor conditions. The tissue culture technique is an alternative method for the propagation of begonia species. It can overcome the difficulties of vegetative propagation and lead to high-quality and uniform planting material under disease-free conditions irrespective of the season and weather. In begonia tissue culture, different species showed diverse responses to the medium composition, especially plant growth regulators. Also, lack of information on large scale micropropagation of begonia in Iran highlights research on optimization of begonia species propagation on in vitro culture condition. Thus, in this study the effect of plant growth regulators on shoot regeneration and proliferation of three begonia species (B. elatior‌, B. soli-mutata, and B. tiger), the impact of Auxin and sucrose on rooting of B. elatior‌and diferent pot substrate on acclimation were survived.

In this experiment, petioles of three begonia species (B. soli-mutata, B. elatior, and B. tiger) were used as explant sources. So explants were washed under tab water for 30 mins and sterilized with 1.5% sodium hypochlorite for 15 mins. After sterilization, thin Cell Layers (TCL) with 2 mm thickness were prepared from petiols and cultured in MS medium with different concentrations (0.2, 1, 2 mg/L) of kinetin (kin) or thidiazuron (TDZ) in combination with NAA (0, 0.2 mg/L). Next, the effect of auxin type (1 mg/L of IAA, IBA, and NAA) and sucrose concentration (30 and 40 g/l) on rooting of B. elatior plantlets were determined on in vitro condition. For plantlet acclimation, sand, CocoPeat perlite mixture (1:1 ratio), and Peat moss as pot substrate were evaluated.

The results showed the shoot regeneration response of begonia species to the plant growth regulators of the medium, and there was a significant difference between them in all of the species adding the Auxin to the medium increased shoot regeneration. In B. elatior and B. tiger lacking of NAA to the medium caused no shoot regeneration. Maximum shoot regeneration (100%) was achieved in B. soli-mutata species in medium containing 1 or 2 mg/L of kin and 0.2 mg/l NAA, in B. elatior at 1 or 2 mg/L of TDZ in combination with 0.2 mg/l NAA and in B. tiger at 2 mg/L of both plant growth regulator (TDZ and Kin) and 0.2 mg/l NAA.

For rooting B. elatior, MS medium containing 1 mg/L IAA plus 30 g/L sucrose was the best and favorite acclimation was acheived in cocopeat perlite mixture and peat moss pot substrate.

Papavear fugax Poir. from Meconidium section of Papaver is an important source for alkaloids. Given the presence of thebain, morphine and codeine in this plant, biotechnological studies, especially In vitro culture of this plant would be of importance. In this study, callus induction and In vitro regeneration of this species from leaf explants in MS medium containing different levels of naphthalene acetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), Kinetin (Kin) and Benzyl adenine purine (BAP) was investigated at 25 °C and 16 h light and 8 h darkness  based on a completely randomized design with three replications. Analysis of variance showed that for callus induction rate and callus weight, there were significant (p<0.01) differences between different culture media. Based on results, the proper medium for callus induction of leaf explants was MS medium supplemented with 1 mg/l NAA and 1 or 0.5 mg/l BAP. The highest callus fresh weight was obtained in MS medium supplemented with 1 mg/l NAA and 1 mg/l BAP. In vitro regeneration of this species from leaf explants was also investigated in MS medium containing different levels of NAA, Kin and BAP and the best medium for regeneration was MS medium supplemented with 1 mg/l Kin and 1 mg/l NAA. By inspecting rooting of seedlings in MS medium containing different levels of indole acetic acid (IAA) plus Kin or BAP, the highest rooting percentage was obtained in MS medium containing 1 mg/l of each of IAA and Kin.

Potato (Solanum tuberosum) is an important crop in tropical countries. Salinity stress is the crucial factor that seriously limits agricultural production in various regions especially in arid and semi-arid areas. Salicylic acid is a bioactive molecule that synthesizes via enzymatic and non-enzymatic pathways under stress conditions in different organs of plant, regulates and adjustments defense reactions of plant. Salicylic acid (SA) is known as a signalling molecule that modifies plant responses to pathogen infection. Many studies have shown that this compound can protect plant under oxidative stresses and maintain chlorophyll. In addition to being an important component of biotic stress tolerance mechanism, SA also regulates various aspects of plant responses to abiotic stresses through extensive signalling cross-talk with other growth hormones. However, exact mechanisms by which SA protects plants during abiotic stresses remain obscure. Salinity stress is the crucial factor that seriously limits agricultural production in various regions especially in arid and semi-arid areas. Salicylic acid is a bioactive molecule that synthesizes via enzymatic and non-enzymatic pathways under stress conditions in different organs of plant, regulates and adjustments defense reactions of plant. Salicylic acid (SA) is known as a signalling molecule that modifies plant responses to pathogen infection. Many studies have shown that this compound can protect plant under oxidative stresses and maintain chlorophyll. In addition to being an important component of biotic stress tolerance mechanism, SA also regulates various aspects of plant responses to abiotic stresses through extensive signalling cross-talk with other growth hormones. However, exact mechanisms by which SA protects plants during abiotic stresses remain obscure.

This experiment was conducted at the plant tissue culture laboratory of Horticultural Sciences, Department, University of Tabriz, Iran, during spring–summer of 2017. The present study was aimed to investigate of salicylic acid effect on betaine aldehyde dehydrogenase gene expression and glycine betainesynthesis in Solanum tuberosum cv. Agria under salinity stress on in vitro condition. The experiment treatments included four level of salycilic acid (0, 1, 10 and 100 mM) and two level of sodium chloride (0 and 70 mM). In the present study, MS media culture was used and sodium nitroprusside was applied for increasing the betaine aldehyde dehydrogenase gene expression (the responsible gene of glycine betaine synthesis) under salinity stress. Four weeks after treatment, total RNA of treated explants was extracted and semi quantitative RT-PCR was used for the analysis of expression of betaine aldehyde dehydrogenase gene.

and semi quantitative RT-PCR was used for the analysis of expression of betaine aldehyde dehydrogenase gene. The glycinbetainecontent was measured with iodide potassium. The survey of betaine aldehyde dehydrogenase gene expression showed increased under salinity stress. Also salicylic acid increased the glycine betaine content in grown plantlets which were grown under normal condition.The expression pattern of glycine betain gene showed tha by increasing of salicylic acid and sodiuom chloride concentration the expression of glycine betain gene has been increased in all samples. however under salinity stress this compound showed negative effect on glycinbetaine content.

In conclusion, antioxidant activity, total phenol and protein were increased salinity stress. In addition, antioxidant activity and glycine betaine content during salt stress period was decreased application of nitric oxide. The glycine betaine content of plantlets in general condition with application of sodium Salicylic acid increased but under salinity stress, Salicylic acid had negative effect on glycine betaine content. The results of this research showed that exogenous application of salicylic acid increased the expression level of genes and lead to enhancement of plant tolerance to salinity stress. Further studies are necessary to determine optimum concentration and duration of Salicylic acid application in order to achieve maximum benefit in Solanum tuberosum tissue culture.

Caber (Capparis spinosa) is the most important species in capparaceae family and is considering as a major medicinal plant. Medicinal usage of this plant are richness of roots, generative buds and fruits for components such as flavonoids’, saponines, pectins, essential oils and specially glycosides and glycosinolates. Considering the importance of Capparis spinose as medicinal plant and its difficulty to reproduction by seed, the present study was performed to optimization of culture conditions for callus induction and regeneration of Caber. This research was performed at Bioengineering and biotechnology research center of Esfahan industrial university. In order to do research, cotyledon leaf, leaf, bud, flag, hypocotyl, root, petals, sepals and node explants were cultured in MS medium with different plant growth regulator compositions. Two levels of 2,4-D (2/5, 3 mg l-1) with kinetin (0/1 mg l-1) and 3 levels of NAA (2, 2/5, 3 mg l-1) in combination with BA (0/5 mg l-1) was used for callus induction. This experiment was carried out in a completely randomized design with 4 replications and 5 explants for each. In order to regenerate shoot from produced calluses, calluses were cultured in MS culture Medium containing hormonal composition of KIN, NAA and IBA with different concentrations. The results of analysis of variance indicated that the effect of explants and interactions of PGR × explants were significant at 1% for dry an fresh callus weight and callus percentage; However, the effect of changes in growth regulator for the percentage of callus was not significant. Additionally, the all PGR combination were appropriate for callus induction in this study, but different explants from different specimens showed different response to callus production, such that the flag explants had the highest percentage of callus (100%) in all PGR compartments. The results of this study demonstrated that the best PGR combination for callus weight, was MS medium containing 0/02 NAA mg.l-1+1 KIN mg.l-1 (with mean 0/27 mg.l-1) and for mean dry weight of callus, MS medium containing 3 NAA mg.l-1 + 0/5 BAP mg.l-1 and MS containing 0/02 NAA mg.l-1+1 KIN mg.l-1 (with an average of 0/026 and 0/027 mg.l-1 respectively). The best treatment for producing shoots from callus was MS medium containing 2 KIN mg.l-1 (40%) and 2 NAA mg.l-1 (40%). Finally the best treatment for rooting was MS medium containing 1 NAA mg.l-1 (30%). In this study, the best plant growth regulators and different type of explants, were optimized for callus, shoot and root production for in vitro condition. Based on the results, the flag explant and all of used media were appropriate for the callus induction. The highest rate of shoot production in In vitro culture was observed on MS medium supplemented by NAA (2 mg l-1), KIN (2 mg l-1) and, for the root production in MS medium containing 1 (mg l-1) of NAA. Therefore use of these treatments and explants, which showed the best calcification and highest production of shoots and roots, is recommended to reproduce this plant under in vitro culture conditions.

Salicornia europaea is a halophytic annual plant of the Chenopodiaceae family, which is considered as an oil plant in marine irrigation. This experiment was conducted to determine the effect of salinity and to reach the best hormonal treatment for shoot regeneration. After washing and sterilization, seeds of S. europaea were cultured under controlled light and temperature conditions at five salinity levels consisting of 0, 100, 200, 400 and 600 mM of NaCl in plots including sterilized soil and vermicompost for 30 days. Germination percentage, germination rate, plant height, the fresh and dry weight of the plant, and relative water content were then recorded. For in vitro culture, the shoot-tips were excided and cultivated in Murashige and Skoog medium containing combinations of various plant growth regulators (BA and NAA including 0 and 100 mM salinity levels) under laboratory conditions, and then plant regeneration was investigated. These experiments were performed in a completely randomized design (CRD) with three replicates. The results showed that high salinity exerted a low effect on seedlings of the Salicornia and the rest of traits indicated high levels of salinity tolerance and showed plant high ability to adapt to salinity. In tissue culture experiment, the results of shoot induction indicated that the hormonal treatments in combination with 100 mM of NaCl provided the better regeneration than that of non-salinity conditions. Increasing use of  the hormone were not given the better regeneration results, but it was needed to use a good proportion of hormone level for shoot regeneration. In the present research, the best possible ratio was the combination of 0.5 mg/l-1 NAA + 0.5 mg/l BA + 0.5 + 100mM NaCl, which resulted in 66.67 regeneration percentage.

Ultrasound has multiple industrial, medical and biotechnological applications. Ultrasound increases membrane permeability and causes several biological effects in plant cells. In this research, the effects of ultrasound on survival and growth of the sainfoin shoot apex explants were investigated. For this, shoot apex explants were exposed to ultrasonic waves (Frequency 37 kHz) for 0, 20, 30, 40, 50, 60, 90, 120, 180, 240 and 300 seconds in a ultrasonic bath and then cultured on MS medium supplemented with 0.1 mg/l IBA and 3 mg/l BAP. Results showed that the percentage of shooting (explants with shoot growth) significantly reduced by ultrasound treatment, but percentage of multiple shoots, number of shoots per explants and percentage of callusing significantly increased. Control treatment (without ultrasound) showed the highest percentage of shooting with the lowest callus induction and percentage of explants vitrification. The highest percentage of callus induction (60.98% and 61.11%) was observed in higher sonication dosages (180 and 240 seconds). While, the highest percentage of multiple shoots, number of shoots per explants and percentage of explants vitrification were obtained in 30 seconds ultrasound treatment. Increasing ultrasound treatment duration decreased viability of plant cells and tissues, and as a result reduced shooting of explants

In order to increase yield in apple orchards, multiplication of rootstocks is essential, and it depends on the availability of a simple and easy proliferation method of rootstocks. The study investigated the effect of disinfection, culture condition and plant growth regulators on the rate of contamination, number of lateral branches, stem length, number of leaves, callus creation and the rate of branch creation of rootstocks MM106, MM111 and B9.
A factorial experiment was carried out as a completely randomized design with three replications. Surface sterilization of explants with different concentrations of mercuric chloride and sodium hypochlorite (mercuric chloride 0.1% for 3 minutes and ethanol 70% for 30 seconds; mercuric chloride 0.1% for 5 minutes and ethanol 70% for 30 seconds; NaOCl 0.75% for 15 minutes and ethanol 70% for 30 seconds) was done and then explants were cultivated in modified MS, WPM and DKW mediums. The evaluated characters were infection percent of explant, number of lateral branches, stem length, percentage of callus induction and number of leaves. Data were analyzed using SAS software. The analysis of variance on the test data was performed at 5% level and comparison to the middle of the Duncan test.
Results showed that using a mercuric chloride (0.1%) and ethanol (70%) respectively for 3 Minutes and 30 Seconds achieved the least contamination. Results showed significant differences between plant hormone and rootstocks for traits. In this test, the modified MS medium with 0.1 mg/L BA hormones with the largest percentage growth had more successful establishment. Average comparisons showed that rootstock MM106 in terms of all traits had a significant difference with other rootstocks. The highest stem length, number of leaves and callus creation were shown in rootstock MM106. In order to investigate the effect of hormone levels on branch creation, different levels of BAP (6-Benzylaminopurine) and IBA (Indole-3-butyric acid) were used. The best medium was the culture containing 0.1 milligrams per liter IBA plus 2 milligrams per liter BAP.
In general, the present results showed that genotypes respond differently to in vitro conditions. The rootstock B9 by the above method showed better response to branch creation trait than other genotypes.

Henbane lattice (Hyoscyamus reticulatus L.)¡ is one of the most important medicinal herbs of the solanaceae family which due to having Tropane alkaloids¡ frequently used in medicinal industry. Medicinal plant Regeneration¡ proliferation and In vitro ploidy induction are one of the interesting issues in biotechnology and plant tissue culture. This study was arranged as a completely randomized factorial design with Two Factors¡ BAP in three levels (0¡ 4.4¡ 8.8 µM) and IAA in three levels (0¡ 1.1¡ 2.2 µM) with three replications. Then¡ In vitro polyploidy induction in regenerated plants was surveyed by 5 different concentrations of colchicine at (0.00¡ 0.05¡ 0.1and 0.2 %) at various exposure times (24¡ 48 and 72 h). in order to determining plant ploidy level¡ microscopic¡ flow cytometry and chromosome counting were performed. The results showed that after six months; the best results (13.13 plantlet in each explants) were obtained in 8.8 µM BAP combined with 2.2 µM IAA. Flow cytometry study results showed that highest polyploid plants (72%) were obtained in 0.1% colchicine with 48 h exposure times. Polyploidy induction was associated with significant changes in plant characteristics. The chromosome number of diploid plants was 2n = 2x = 34 and in tetraploid plants was 2n= 4x =68. Therefore¡ can say that colchicine effectively induce polyploidy in the plant.

In vitro propagation of three Iranian apricot cultivars, “Ghavami”, “RajabAli” and “Khiveei” was studied by direct micropropagation technique. To optimize sterile manipulation, shoot nods of one year-old dormant vegetative shoots and current growing vegetative shoot were cultured in WPM medium after treatment by HgCl2, citric acid, ethanol and NaClO (10, 15, 20 min). Establishment of buds was tested in the MS and WPM mediums. Proliferation of sprouting buds was evaluated in WPM medium supplemented with three concentrations of (0.5, 1 and 2 mg/l) BAP and 0.05 mg/l of IBA. A half-Strength MS medium supplemented with three concentrations (0.5, 1 and 2 mg/l) of IBA was used as a rooting medium. The greatest number of contamination-free shoots in HgCl2 0.01% and citric acid 0.07% treatments were obtained. No significant difference was found between two different mediums in terms of bud vegetative growth. The shoot number and length were significantly affected by apricot varieties and BAP concentrations. The greatest numbers of proliferated shoot were observed in Rajabali and Ghavami varieties at 1 mg/l of BAP, whereas maximum number of shoot in Khiveei cultivar was observed in 0.5 mg/l of BAP. The maximum shoot length in Rajabali and Ghavami cultivars was obtained in 2 mg/l of BAP.

One of the major advantages of in vitro culture of African violet (Saintpaulha ionantha) is production of new cultivars and propagation of their chimera which might not be propagated by the other methods. In this study, we tested the effects of silver nanoparticles on the sterilization rate (antifungal and antibacterial activity), regeneration and shoot formation of African violet "Pink Amiss" explants. These nanoparticles were synthesized from pomegranate peels and Damask rose petals extracts. We used a completely randomized design test with factorial arrangement to investigate various volumetric ratios of plant extracts to silver nitrate (1:20, 1:10, 1:5 and 1:1) on the culture contaminations. Using silver nanoparticles synthesized by the plant extracts, especially Damask rose petals extract resulted in no fungal and bacterial contamination in the African violet explants after 1 and 3 weeks as compared to the control, and silver nitrate (1mM). All tested concentrations of the silver nanoparticles significantly (P ≤ 0.05) controlled both bacterial and fungal contaminations. The 1:20 ratio of plant extracts to silver nitrate showed the best control. In addition, the highest regeneration (%52) and shoot regeneration (%38) was observed in this treatment. In conclusion, we suggest using silver nanoparticles synthesized by plant extracts for sterilization of in Vitro Culture for African Violet rather than using other chemicals such as silver nitrate.

Saffron (Crocus sativus L.) is one of the medicinal plants that contain active components and medicinal materials. Tissue culture of saffron can improve the quality and quantity of the saffron product, increase its export and the farmers’ income. In this study, 36 different types of hormone combinations in the dark and 9 different treatments of hormone combinations in cold (4°C), using different saffron explants (bulb, leaf, scales around leaf and distal parts of the leaf) were studied in tissue culture. To investigate the growth of corms, the callus formation and the regeneration rate, three replications for each treatment were used and the length of shoot (cm), the callus formation percentage and the regeneration percentage were measured and statistical analysis was performed. Among the types of explants, only explants from bulbs produced the callus on MS medium containing 2 mg.l-1 BAP and 1 mg.l-1 IBA in both the dark and cold conditions. The highest percentage of regeneration was obtained in MS medium with hormonal composition of 0.3 mg.l-1 TDZ, 1 mg.l-1 BAP, 2 mg.l-1 IBA and 0.01 mg.l-1 GA3 in the cold conditions.

German chamomile (Matricaria chamomilla L.) is one of the most important medicinal plants that its essential oils used in different medicinal industries. In this study which was carried out in 2013 growing season at the Faculty of Agricultural Sciences of the University of Mohaghegh Ardabili, the in vitro response of leaf and hypocotyl explants of German Chamomile in B5 medium supplemented with different levels of plant growth regulators including 2,4-D, naphthalene acetic acid (NAA), kinetin and 6-benzylaminopurine (BAP) were investigated in a factorial experiment based on completely randomized design (CRD).In addition, cell suspension cultures were established and characterized. Hypocotyl and leaf explants exhibited cell proliferation and produced callus within 1-2 weeks. The highest fresh weight of the callus (264.1 mg) was produced by leaf explants in the medium supplemented with 0.5 mg/l 2,4-D and 1 mg/l BAP. However, the leaf explants cultured on medium containing 1.5 mg/l 2,4-D showed the lowest cell proliferation and callus yield (40.42 mg). The highest percentage of root induction from leaf explants (58.73%) was observed on the medium containing 4 mg/l 2,4-D and 1 mg/l Kin, and from hypocotyl explants (48.61%) was observed on medium supplemented with 1.5 mg/l NAA. The 42.22% of calli derived from hypocotyl explants on B5 medium supplemented with 4 mg/l NAA and 3 mg/l BAP, were friable. Cell suspension cultures of German chamomile were established by transferring of hypocotyl-derived friable calli into the MS medium supplemented with 1.5 mg/l 2,4-D and 1 mg/l kinetin. The growth curve of cell proliferations started 4 days after culture and continued to grow until day 13th, where the cells entered stationary phase.

Salinity tension is considered as a restricting factor for plant productions. In this research the effect of paclobutrazol as a triazole regulator on morphological and biochemical indices of Brassica (napus L.) seedlings under salinity tension in vitro culture conditions has been investigated. After rinsing and sterilizing the seeds of B. napus L. ten seeds were cultured in morashig and oscog base cultures environment consisted the concentrations of 0, 50 and 100 mM sodium chloride )various levels of salinity) and concentrations 0, 5, 10 and 20 mg per liter paclobutrazol. After 4 weeks, the obtained results showed that stem and root length, stem and root dry weight, chlorophyll a content, total chlorophyll and seedling carotenoids in salinity tension significantly decreased. Whereas, the amonth of lipid peroxidation and restore sugars and proline increased in salinity tension. Paclobutrazol increased the amonth of morphological and biochemical parameters of seedlings in all levels either in salinity tension situation or normal situation a lot. Therefore paclobutrazol treatment in B. napus L. seedlings under salinity tension improved tension symptoms and damages due to salinity in these seedlings.

Birch (Betula sp.) is considered as extinction species and its natural regeneration in Iranian forests is very slow. Difficulties in regeneration as well as natural seed germination of birch tree besides high levels of seed contaminations have justified the application in vitro culture with respect to its conservation and genetic improvement. Hence, the in vitro culture initiation using seed explants of two birch species was attempted. The seeds of B. pendula (collected from Sangdeh altitudes, Mazandaran) and B. litwinowii (from Siamarzkooh forests, Golestan region) were randomly harvested from the ten adult trees and then subjected to 7 surface sterilization treatments in 3 replications. The experiment was undertaken as completely randomized design in factorial arrangement (two factors) and 15 replications per each treatment. Application of Difnoconazole fungicide (3% for 24 h) followed by warm water (55°C in 30 min) and HgCl2 (0.1% for 10 min) were recognized as the best treatment for seed sterilization as well as germination. With this treatment, 95-100% seeds were found to be free from bacterial and fungal contamination. Consequently, seeds of two species were cultured on MS and B5 media. The germination percentage for B. litwinowii and B. pendula were recorded as 17.3% and 14%, respectively. In conclusion, these in vitro raised plantlets may be used as a source explants for in vitro culture initiation of birch species, whose seed collection is so difficult in such impassable sites.