مجله پژوهشهای گیاهی (زیست شناسی ایران)
سال بیست و هفتم شماره 1 (بهار 1393)

Cadmium as a heavy metal plays an important role in environmental pollution and making toxicity and stress in living organisms. In order to evaluate the effect of cadmium on the growth of wheat، five durum and bread wheat varieties were studied under five different cadmium doses in hydroponic media. Analysis of variance showed that the effect of cadmium was significant for all the measured parameters except the biomass and root length tolerance index. Cadmium accumulation in shoots and roots of the wheat varieties was increased by exposure to cadmium. The varieties of durum wheat had more accumulation than bread wheat varieties. Cadmium caused to decrease in the total dry weight (biomass)، shoots and roots of wheat seedlings. The rate of total dry matter production and shoots were more sensitive to the presence of cadmium than roots. The physiological parameters including stomatal conductivity، chlorophyll content and Fv/Fm had decline trend along to increasing cadmium. Overall، the results of this study suggested that the all growth and development processes of wheat were influenced by cadmium; also there was considerable difference among wheat genotypes at inter- and intra-specific level.

This research was carried out in Zagros Collection of National Botanical Garden of Iran، with an area of 3. 2 ha. The objective of this research was to calculate the best allometric models for estimation of leaf biomass and carbon stock of oak species (Quercus brantii، Q. infectoria & Q. libani). Furthermore، we estimate the leaf carbon sequestration in studied species. For each species، 15 sample trees were selected، numbered and their quantitative variables measured. The leaves of a sector of the tree crown were picked off and after weighting، their dry weight were measured in laboratory. Enough quantity of leaves was burned in electrical kiln to calculate the carbon storage. Finally، amount of atmosphere CO2 absorption was determined and allometric regressions were calculated using power regression model. Based on results، the mean of leaf biomass for Q. brantii، Q. infectoria & Q. libani were 282. 1، 216. 3 and 152. 3 kg per hectare، respectively. In adition، the mean of leaf carbon stocks were 140. 2، 107. 3 and 75. 6 kg per hectare، respectively. The best power regression model for Q. brantii and Q. infectoria was resulted from DBH variable، while the mean of crown diameter had the main role in Q. libani.

This research aims at investigating the biosorption of cadmium and lead cations from aqueous solution using brown alga، Cystoseira indica. Adsorption capacity of this alga affected on pH concentration، when pH of solution increases، the amount of both metals adsorptions by alga rise. Generally، the most suitable pH for biosorption of the alga ranges between 6 and 7، more specifically، the maximum adsorption rate for Cd (II) and Pb (II)، for 1 g and 2. 5 g were 79. 1%، 89. 2% and 73. 2%، 69. % respectively. The other environmental factors which influence the adsorption of this alga include the time of adsorbent contact and environment temperature، when time increased from 10 to 40 minutes، the amount adsorption increased too. The maximum capacities of adsorption for both metals were in temperatures between 40 and 50 °C. This research also examined the effect of biomass concentration alga on the adsorption capacity. The obtained results indicated that there was no significant change in adsorption capacity. In addition، kinetic investigations showed that speed pseudo-second-order model equation of both metals for 1 and 2. 5 g of alga biomass with constant speed were 11. 14،12. 1*10-3g mg-1 min-1 and 12. 41،8. 96*10-3 g mg-1 min-1 for cadmium and lead respectively. The results show that kinetic data fallow speed pseudo-second-order model. Experimental equilibrium data was fitted by Freundlich isotherm more than Langmuir isotherm. The results show that the alga Cystoseira indica can be used for treatment of aqueous solutions containing cadmium and lead as a low cost adsorbent.

Soil salinity is a serious environmental problem that has negative effect on plants growth and production. On the other hand، salicylic acid is one of strong candidates for stress ameliorators that have been recently recognized as a plant hormone like substance. This study was conducted to investigate effects of salt stress (180 mM) and salicylic acid (0. 2 mM) on growth parameters and osmolytes in radish (Raphanus sativus) plant. Results released that salicylic acid and salt stress had negative effect on growth parameters. The effect of salt stress with salicylic acid on growth of plants was obvious. Salt stress and also salicylic acid increased soluble sugars of leaves and roots. Whereas salt stress didn’t have any effect on amino acids، salicylic acid caused to increase that in leaves and root tissues. Content of soluble proteins decreased under salt stress and increased by salicylic acid treatment. Both of treatments caused more negative osmotic potential.

Current research includes the effects of forest roads on changes of plant covering and structure of plant species from forest roads edges towards its inner parts in three areas and two different asphalt and dirt roads. There are the same conditions according to topography، slope and direction for studied areas. On the two sides of road، it was used 2m × 2m micro plots for measuring of biodiversity and floristic composition. The results showed that biodiversity indices had no significantly differences in relation to studied regions، roads around and roads type. But، the road positions were effective on biodiversity amounts، as indices values were reduced with distance increasing of roads for both of paved unpaved roads. Some of light–demanding species such as Alnus glutinosa (L) Gaertn، Sambucus ebulus L. Rubus hyrcanus juz were more visible in the around of roads.

Different herbicides especially Metribuzin are used to control of weeds in vegetable farms throughout the world. Such chemicals may have some adverse effects on the crop. In order to evaluation of alleviating effects of arbuscular mycorrhizal colonization on toxicity due to herbicide Metribuzin، a study was performed using squash plants and Glomus etunicatum fungus. The experiment included two factors: mycorrhizal (M) and non-mycorrhizal (NM) squash plants and four levels of the herbicide concentrations (0، 0. 002، 0. 005 and 0. 02 gL-1) in 3 replicates. In this study، dry weight، photosynthetic pigments content (including chlorophylls a and b)، total protein and sugars content of shoots and roots of M and NM plants were reduced with increase in metribuzin concentration. This reduction was less obvious in M plants in comparison with NM ones. Also، proline content wasraised in M and NM plants but this increase in mycorrhizal plants was higher than non-mycorrhizal ones. Overall، the obtained results may indicate improvement of physiological status of squash plants due to arbuscular mycorrizal colonization by G. etunicatum against Metribuzin toxicity.

Ziziphora clinopodioides is one of the aromatic and medicinal plants belong to Labiatea family. The essential oil of this plant contains pulegone with many medicinal properties. The aim of this study was identification of natural habitats of Z. clinopodioides In Hamedan province and effects of ecological factors on it’s essential oil content and composition. So the aerial parts of Z. clinopodioides were collected from 11 localities at flowering stage and dried in shade and room temperature. Some ecological factors like geographical characters، height، slope percent and other plant species were determined. The soil of each collection site from 30 Cm depth was also analyzed. The plant materials were subjected to hydro-distillation for extraction their essential oils in three replications. The oil yields were calculated based on dry weight. The chemical constituents of essential oils were identified by using GC and GC/MS. The results showed that oil yields have significant difference at % and 5% levels. The highest oil yield was observed for Z7 and the lowest for Z11. Twenty six components were identified in the oils that the percentage of main compounds، pulegone and 1،8-cineole، was different in samples from different localities that showed the effect of ecological factors.

In this research، density of Amygdalus eburnea Spach was evaluated on rangelands of Shahr-e Babak (Kerman province) in summer season of 2008 in habitats with high، medium and low densities by six quadrat، linear transect، Byte & Ripley، T-square sampling، ordered distance method and point-quarter method. The goal of this study was determination of the accuracy and effectiveness (speed of performance) of these methods. For comparison of the methods with control used T-student Analysis. Between the used methods for estimating density، quadrat method had significant difference with control method (p<0. 05) and the other methods hadn’t significant difference with control method. Comparison of the methods in habitats with different densities of the species showed that ordered distance، T-square and linear transect methods with highest accuracy and lowest relative difference of density were the best methods in habitats with low، medium and high densities، respectively. Quadrat method with least accuracy and highest time consuming was the unsuitable method in habitats with medium and high densities. In habitat with low density، linear transect method didn’t show acceptable accuracy. In general، for evaluation of density in Amygdalus eburnea habitats based on least time consuming and highest accuracy، T-square method is recommended.

Heracleum gorganicum Rech. f. is one of the endemic medicinal plant species of Apiaceae family، which is native to humid northern mountainous regions of Iran. The aim of this study was investigation of the chemical composition of essential oils from fruits of four wild growing populations of H. gorganicum. Mature fruits were collected from their natural habitats in Golestan، Gilan and Alborz provinces. The oils were obtained by hydrodistillation and were analyzed by gas chromatography (GC) and GC-mass spectrometry. The essential oil yields of populations were ranged 2. 8% (Ramiyan) to 4. 8% (Rasht) based on the dried plant material. Thirty-five compounds، which accounted for 93. 47- 96. 85% of the total oil، were identified in the essential oils. Hexyl butyrate and octyl acetate were the two major components in the essential oils of populations. Essential oils of Shahrestanak and Rasht populations with 30. 88 and 49. 28%، respectively had the highest and the lowest amounts of hexyl butyrate. The lowest (14. 06%) and the highest amounts (21. 65%) of octyl acetate were obtained for essential oils of Ramiyan and Drazno populations. Cluster analysis based on the percentages of the essential oils components showed that two populations of Ramiyan and Rasht were placed in one cluster and two the other populations of Shahrestanak and Drazno were also positioned in the second cluster. In conclusion، it seems that the observed variations in the composition and the content of essential oils were more affected by the genetic factors and from the climatic factors، a positive correlation was obtained between altitude and the quantitative changes in the essential oils.

In order to study the genetic variation and relationships among traits، an experiment on 15 genotypes of Dracocephalum moldavica L. under field conditions was carried out in a randomized complete design with 4 replications in Payam Noor University، Esfahan. Morphological charaters، including fresh and dry herb yield، plant height، stem diameter، number of auxiliary shoots، number of leaves/plant، 1000- grain weight، essential oil yield and essential oil content. Results of analysis of variance showed، significant differences for all studied traits (p< 0. 01) with the exception of essential oil content. High values of phenotypic and genotypic coefficients of variation were obtained for most traits، indicating high variability in the traits under study. Essential oil yield varied from 0. 49 (ml/pot) in genotype Khomeini Shahr to 0. 81 in genotype of Birjand. Essential oil yield had a significant high and positive correlation with fresh herb yield، number of auxiliary shoots، plant height، dry herb yield and essential oil content. Cluster analysis grouped the 15 genotypes within 3 groups. Genotypes in first group had higher essential oil yield، fresh herb yield، dry herb yield، plant height and number of auxiliary shoots. Our results indicate the presence of comparable genetic potentials in genotypes of Dracocephalum moldavica L. for cultivar development.

The allelopathic effects of six weeds including Conyza bonariensis، Acroptilon repens، ­Artemisia annua، Inula graveolense، Solanum nigrum and ­Xanthium strumarium­ on seed germination and seedling growth of wheat was investigated using a complete randomized design with three replication in laboratory and glasshouse of college of agriculture، University of Gorgan in 2009. The result showed that shoot extracts of Xanthium strmarium، Acroptilon repens and Conyza bonariensis significantly reduced germination rate of wheat in 47، 42 and 25 percent، respectively. Also، shoot and root extracts of these three plants reduced coleoptile length، root length، and root dry weight of wheat seedlings. Roots appeared more sensitive than shoots respective to allelopathic effects. Aqueous extracts were more phytotoxic than dried plant extracts and also shoot extracts had higher detrimental effects than root extract. In general، shoot extracts and residue of three plants mentioned، significantly reduced germination، root length، shoot length and root dry weight of wheat seedlings. Therefore، extract of Acroptilon repens might contain numerous growth inhibitors that could be used for the development of biological herbicides.

In the present study، the changes in physiological and biochemical attributes during flower senescence in petals of four different cut rose cultivars (Avalange، Yellow Island، Cool Water and Bakara) was investigated. Water uptake، fresh weight، flower diameter، protein content، lipid peroxidation and proline concentration were determined. There was a significant difference for vase life among investigated flowers، the highest vase life was found in Avalange cultivar with white petal color and the lowest one was found in Cool water with pink color. In all cultivars، fresh weight was the highest during bud stage and thereafter، that declined to senescence. The lowest water uptake was found in pink Cool water and the highest in white Avalange. Protein content was highest during bud stage and thereafter، decreased gradually during senescing of rose petal. Avalange with the longest vase life exhibited the highest protein content during different interval stages; Cool water had the lowest protein. Lipid peroxidation was increased with onset of senescence especially، but its level declined in senescence flower petals. Overall، increasing in lipid peroxidation and proline accumulation and declining protein content in petals may be resulted from oxidative stress.

In vitro propagation of Damask rose via single nod explants was investigated on 3 different basal media، Murashige and Skoog (MS)، Lioyl and Cown (WP) and Quoirin and Lepoivre (QL). The effect of different basal media on shoot proliferation and media browning was studied. The highest percentage of proliferation was achieved on QL medium. Explants grown in the above media were transferred to the same media supplemented with BAP and Kn (1. 3 mg/l) for shoot proliferation. The highest shoot proliferation response and shoot growth was recorded when shoots were cultured in QL medium with 3 mg/l BAP. Comparison of different media (MS، WP، QL) based on number of shoot، leaves، leaflet number and shoot length indicate that QL medium was the best compared to other media for Damask rose in vitro micropropagation. Rooting of the regenerated shoots was induced on WP medium supplemented with 0. 2 mg/l NAA.

This study explores the influence of climate and environmental changes on 5 tree species (Cupressus arizonica، Robinia pseudoacacia)، Fraxinus rotundifolia، pinus eldarica and Celtis australis) in Lavizan plantation forest park، which is located in northern part of Tehran. Although، recreation parks are under irrigation، but still trees and vegetation cover are influenced by environmental and climate factors. In this research، dendrochronology study method have been used to identify different reaction of these five tree species to environmental and climate changes. Plants، especially، trees are sensitive to their environmental changes، and tree-ring width is one of the reliable proxies of ambient environmental conditions. Climate and environmental changes affect natural ecosystems as well as planted forests. This study has been conducted in 5 study plots in the park and instrumental data were derived from nearest meteorological station (Shomal e Tehran station) from 1988-2008. Correlation analysis was used (with SPSS Statistics Package and Excel) to explore relationship between climate and measured tree-ring widths. All the species show obvious decrease in tree ring width، in result of increasing temperature in the last 20 years. Substantially، environmental parameters like soil characteristics، gradient، slope direction and air pollution، affect the growth elements in all species.

In this study the effects of root colonization and different soils mycorrhiza on the growth of corn (Zea maize) under salinity stress was investigated. Four soil types of different area in Kerman province (Kerman، Bardsir، Baft and Rafsanjan) and three levels of salinity (0، 30 and 60 mM NaCl) were employed. The root colonization percent decreased in the plants grown on Kerman and Baft soils as the salinity increased. The colonization percentage of the plants grown on Bardsir soil increased at 30 mM salinity. The amounts of sugar in leaves and roots of the plants grown on Kerman and Bardsir soils increased but of those grown on Rafsanjan soil decreased. At 30 mM salinity، in some case prolin content increased in leaves and roots of the plants grown on Bardsir and Rafsanjan soils. the amounts of roots Na increased in plants grown on all the soil types. In the leaves، Na concentration in plants grown on different soils type was lower in compared with control plants except of plants grown on soils of Kerman and Rafsanjan at 60 mM salinity. The amount of P in the plant leaves of the plants grown on Kerman Soil، and P contents of the roots on Kerman، Bardsir and Rafsanjan soils increased. According to the results، it is speculated that the most probably mechanism involves in the growth improvement of mycorrhizal plants is preventing of Na uptake and its transition into the leaves.