Journal of Plant Research
Year:2015 | Volume:28 | Issue:1|Papers Count:20

Diversity of plant species in a community changes in response to topographic factors such as altitude, aspect and slope. This study examined diversity changes in relation to topography in Dodangeh forests, in the south of Sari, Iran. Plant species were collected in sample plots and the cover percent of each species was recorded using quadrat plots of 400 m2 and 237 plant species were characterized in the area. All the quadrats were divided into 7 altitudinal, 3 slope and 8 aspect classes. Discriminant function analysis showed that altitude is the most effective factor to discriminate plant communities. The data were also subjected to analysis by specific diversity packages to characterize and obtain species diversity and evenness indices as well as species abundance models. Results showed that the highest species diversity (Shannon's index (H)=1.5-1.6) and evenness (Smith & Wilson’s index (E)=0.38-0.42) were observed in the moderate levels of altitude. Also it was found that the south, southeast and southwest facing slopes were more diverse than the northwest ones because of more available radiation and temperature. So, vegetation of the area accords with Gleason’s continuum view of communities.

Because of the importance of medicinal plants in curing diseases and the shortage of natural habitats, little reproduction rate and mass cutting of trees, it is necessary to program cultivation and naturalization of medicinal plants. The aim of this research was to determine the most suitable treatment to overcome seed dormancy and induce Thymus transcaucasicusand Zataria moltiflora to germinate. So, seeds of the species were collected from their original habitats and they underwent the treatments before their vegetation, including gibberellic acid (100, 500 and 1000 ppm), cold (10, 20 and 30 days), 1M thiourea and KNO3. The seeds were sown in petridishes for 15 days. This experiment was conducted in a completely randomized design with four replications. Results of the analysis showed that the effect of various treatmentson the percentages of Thymus transcaucasicus and Zataria moltiflora seeds germination were highly significant (p<0.01). Treatments of 100 ppm gibberellic acid and cold (10 and 20 days) have the highest effect on seeds germination percentage of Thymus transcaucasicus and KNO3 and cold (10 and 20 days) on Zataria moltiflora seeds. The highest and lowest vigor indices in Thymus transcaucasicus were seen under treatment of 100 ppm gibberellic acid (16.2) and KNO3 (2.4), and were also seen in Zataria moltiflora under treatment of 1 M thiourea (10.9) and cold for 20 days (1.37).

Saline land area is increasing and salinity is one of the most important challenges in the world. The investigations have showed that salinity decrease seed germination and limit plant growth. Arachis hypogaea is an annual legume that belongs to fabaceae family and because of high oil quality and protein content is cultivated in 109 countries. In order to study the effect of different levels of salinity on germination of four genotype of Arachis hypogaea (Local cultivar, ICGV95148, ICGV96177 and ICGV03060) an experiment was conducted using four levels of NaCl (0, 50, 100 and 150 mM) in plant physiology laboratory, University of Guilan. The seed germination percentage and speed were examined at fifth, seven, ninth, eleventh and thirteenth days. On day thirteenth, length of radicle and plumule and their ratios, fresh and dry weight of seedling and seed vigor determined. Results showed that salinity and cultivar has a significant effect on all of the examined characteristics except for dry seedling weight and length of radicle. Moreover the results indicated that the interaction effect of cultivar and salinity had a significant effect on germination percent and speed, length of radicle and radical length /plumule, Total of length of radicle and plumule, seedling fresh weight and seed vigor. Local cultivar was found the most tolerant cultivars to salinity.

Antibiotic resistance has prompted the use of medicinal plants with less side effects instead of common drugs. The present study was done to investigate antibacterial effects of garlic ethanolic extract against antibiotic resistant Staphylococcus aureus strains isolated from nasopharyngeal samples. Extraction was done using vacuum distillation (rotary). A total of 17 Staphylococcal strains were isolated from nasopharyngeal swabs of in- and outpatients in Ali-Ebne-Abitaleb hospital (in Zabol). Antibiotic resistance was determined using Kirby Bauer method and minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of garlic extract was determined using antimicrobial susceptibility testing - microbroth dilution. Antibiotic resistance of the isolates was as follow: Penicillin (88.2%), Erythromycin (82.4%), Cefoxitin (82.4%), Trimethoprim (70.6%), Ampicillin (70.0%), Ceftazidime (29.4%), Tetracycline (23.4%), Ceftriaxone (23.5%), and Amikacin (5.9%). The MIC and MBC for garlic extract were 1.25 and 5 mg/ml respectively. Garlic extract has high anti-staphylococcal effects compared to common antibiotics and could be used as a beneficial medicinal plant. However, more studies to make sure of its medical effects before wide medical usage is required.

Titanium is not an essential element but it has been reported that it is useful for better growth and improvement of metabolic processes in plants. In this study, the effect of titanium on growth rate and synthesis of pigments, rate of photosynthesis and respiration of algae was investigated. For this purpose, the different concentrations of 0, 100, 150 and 200 mM of Ti+3 were applied to the culture medium of D. salina in 3 replications. Based on these results, any significant changes in the mentioned parameters weren’t observed in the all treatments compared to the control, but the parameters showed marked increasing in the presence of EDTA. Effect of pH was similar to the results of titanium effect in the presence of EDTA. Photosynthesis and respiration in the long-time treatment of 150 mM of Ti+3 decreased over 24 hours. In the short-time treatment, photosynthesis increased by the increase of titanium concentration in the medium by 150 mM. Higher concentration had a negative effect on photosynthesis and respiration. Respiration in 50 mM of Ti+3 increased in comparison with the other concentrations and it was decreased with increasing Ti+3 concentration by 200 mM.

This study was carried out to investigate the relationship between vegetation and environmental factors of Quercus petraea habitat in the district No.8 of Asalem forests, Guilan. Data were selectively collected in 30 sampling plots of 50 m×50 m. In each plot, diameter at breast height (dbh) of trees³ 10 cm were measured considering the tree species. Herbaceous species data were taken using Whittaker’s nested plot sampling, the species coverage were estimated using Domin criterion, and types of the species were identified in each plot. In addition, the most important topographical factors were recorded in each plot. Soil samples were taken from depths 0 to 20 cm in each plot center and to characterize ecological species groups, TIWNSPAN method was used. Also, Canonical Correspondence Analysis (CCA) was applied to study relationship between environmental factors and vegetation composition on plot level. Results indicated that there are four ecological groups in the studied area; and that elevation, aspect, bulk density, gravel percent, organic carbon, organic matter and total nitrogen were the most important factors in determining the ecological groups.

Environmental pollution with heavy metals is increasing and lead is one of the most important pollutants of the environment. In this research, Solanum melongena which is one of the main agricultural plants in Asia and Africa continents was selected and the developmental stages in its pollen grains were studied. To this purpose, by CRD method with 4 treatments, the experimental plants were treated with different concentrations (0 mM, 3 mM, 6 mM and 9 mM) of lead acetate. Then the flowers were collected in different developmental stages and fixed in FAA; afterwards they were subjected to developmental studies with photomicroscope. The results showed that lead treatment could influence developmental stages of pollen grains, so that the increase in lead concentration increases abnormalities in plants. Some of these abnormalities in the plants treated by lead acetate were accumulation of dark particles, vacuolated pollen grains, changes in natural shape of the pollen grains, deformation of tetrads and pollen walls and decrease in fertility and viability in the pollen grains.

In order to study the anatomy and ontogeny of generative meristem ofZizyphus jujuba, its generative meristem and young buds (tiny to mature buds) were removed in different developmental stages, and then fixded in FAA, afterwards they were embedded in paraffin and sliced at 7-10 μm. Staining was carried out with Hematoxylin – Eosin and the generative meristems and young buds were studied with light microscope. Results showed that vegetative meristems were developed to generative meristems and different components of flower were formed. Another primordium and carpel primordium and petals were formed from sporangiare meristem and sepals were formed from initial ring. Also carbohydrate and protein contents and antioxidant enzymes activities of the plants leaves were measured in different seasonal conditions (spring and summer 1390) in two provinces Mazandaran (Behshahr) and Golestan (Galikesh) to understand how they become adapted while the climate changes. By seasonal changes, levels of proteins and peroxydase activity increased in both cities, while catalase and ascorbate peroxydase activities reduced. Soluble and insoluble carbohydrates levels didn’t have any significant difference. Proteins levels and peroxydase activity were more in Behshar while more catalase activity was seen in Galikesh.

In order to investigate the influence of soil factors on plant diversity and ecological groups in the North Khorasan province, an area of 220 hectares of Joezak-Darkesh forest was studied. At first, 55 sample plots each of 20 m×20 m were selected to determine the vegetation. Then, 18 samples from superficial layer of the soil (from 0- 10, 10-20 and 20-30 cm depths) were taken and their electric conductivity, pH, organic matter (OC), total nitrogen, available phosphorus, soil texture, K and C: N ratio were measured. Ecological groups of indicator species were detected using TWINSPAN (two way indicator species analysis) and the study area was divided into five different ecological units Cotoneaster integeryma (A), Fraxinus excelsior (B), Prunus divaricata (C), Carpinus betulus (D) and Acer laetum (E). Analysis of ecological species groups showed that different groups had significant differences (p<0.05) in Simpson' s Diversity Index (SDI). Duncan’s test revealed that the highest species diversity was allocated to E, B and D ecological groups, respectively. This is while no significant differences were detected among the ecological groups in terms of the other biodiversity indices. Pearson regression analysis displayed that rise in pH in the 3rd depth of the soil had negative effect on the SDI and Margalef's species richness index. The amount of OC and K in the first soil depth had positive effect on the SDI. The other soil characteristics did not affect the diversity indices. It was deduced that among the affective factors, OC and K amounts of the first soil depth separated the five ecological groups in the investigated site.

 Biology Dept., Payame Noor University, Tehran, I.R. of Iran Absract In this study, the influence of foliar application of different concentration of Na2SeO3 (1.5, 10 and 100 mg l-1) on some physiological parameters in Triticum aestivum L. was investigated in two cultivars of spring wheat. The results indicated that application of selenium (Se) increased biomass accumulation in Zagros and Chamran cultivars. The highest content of Se accumulation in grain (1.01 mg kg-1 DW in Zagros and 0.465 mg kg-1 DW in Chamran) was detected under application of 10 mg Se l-1. Concentrations of malondialdehyde (MDA) and hydrogen peroxide (H2O2) remained unchanged in Sesupplemented plants obviously because of an efficient scavenging following significant enhancement of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities. These results suggest that foliar application of 10 mg l-1 Se alleviates oxidative stress and causes a significantly higher growth rate in both cultivars. In addition, our results indicated that Se can be used for bio fortification of wheat grains which thus, leads to increasing dietary Se intake in human.

In this study, the effect of forest management was investigated in managed and unmanaged natural forest stands at district 7- Shenrood (Siahkal). Parcel 2 of the given district (81 ha) was selected as an unmanaged region while parcels 3 and 4 (80 ha in total) were considered as managed ones. The survey was done based on a systematic method. However, the starting sampling point was selected based on a randomized method. The dimensions of the survyed area were 200 m × 100 m with circular plots each of 0.1 ha. At each sampling plot, we investigated the kinds of species, their diameter at breast height (DBH) of more than 12.5 cm, the height of two control trees and the quality condition of trees. We also recorded all tree regenerations with DBH of less than 12.5 cm. The results showed that there are no significant differences between the trees in average of the cross-sections, volume per hectare and the degree of tree quality in managed and unmanaged parcels. There were also no significant differences between numbers and standing volume per hectare, Lorry’s mean height and mean regeneration in the managed and unmanaged forest stands were at 0.05 confidence level. The composition of beech species was found 83.87% and 97.15% in unmanaged and managed parcels respectively. It seems that management practices in forest stands caused an important change from the mixed beech forest stands to the pure, and it also increased reestablishment of plants mostly beech trees. The results also revealed that the altitudes range is suitable for establishment of beech species.

Edible pistachio (Pistacia vera L.) is an important species of Pistacia genus and Anacardiaceae family. The morphological and anatomical traits of the male flower, anther and pollen grain developmental stages of the pistachio were investigated by cytohistological methods. The results showed that the inflorescence of the male flowers is grape and they have 4-7 stamens with large anthers, 2-3 sepals and 0-1 brackets. Two sacs of each side (theca) of the anther are completely separated from each other and have complete longitudinal dehiscence at the connective area. The cytoplasm division and microspore mother cell meiosis occur simultaneously. The resulting tetrad is tetrahedral and the tapetum layer is glandular. The number of the layers of the middle layer is three or more. These are remarkably viable and degenerate with tapetum at the end of the maturation or even at the time of anther dehiscence. The mechanical layer has fibrous ornamentation and the epidermis is settled on. The pollen grains are circular with 3-5 germinative pores and are brochate in surface.

Drought stress is one of the most important factors limiting the survival and growth of plants in the different habitats of Iran. Detailed knowledge about the ecophysiological responses of native plants to drought stress could contribute to the success of re-vegetation programs. Different accessions of two perennial chamomilesAnthemis tinctoria and Tripleurospermum servanes were subjected to four drought treatments, i.e. well-watered (control), mild drought stress (75% of field capacity), moderate drought stress (55% of field capacity), and severe drought stress (35% of field capacity). Then osmotic solutes (proline and soluble sugars), Relative water content (RWC), antioxidant enzymes (peroxidase and polyphenoloxidase) and pigments were investigated. In both of the studied species, drought stress significantly increased accumulation of osmotic solutes, but decreased relative water content, total protein content and dry weight percentage. Also, the chlorophyll a and total chlorophyll contents did not change in the drought stresses, however the carotenoids content and the ratio of carotenoids to total chlorophylls significantly increased. Although the peroxidase activity, as an antioxidant enzyme, in all three accessions of T. servanes increased under severe drought stress, but in two accessions (of three accessions) of A. tinctoria, it considerably decreased. These findings suggested that the A. tinctoriaand T. servanes showed a moderate tolerance to drought, although in both of the species, there were as well some accessions which had higher tolerance to severe drought stress than the other accessions because of their higher capacities of osmotic adjustment.

In this research, Rhizobium strains from nodules of alfalfa plants and Bacillus strains were isolated from field soils in Dowlatabad, Isafahan. Salt tolerant strains were detected by drop plate method on YMA and PVK culture media containing 100 mM NaCl. Then, the seeds and seedlings of two alfalfa cultivars (Yazdi and Hamedani) were inoculated singly or both simultaneously with strains ofSinorhizobium and Bacillus species and then were grown in 2 levels of salinity (0 and 100 mM NaCl). Results showed that salinity increased the electrolyte leakage and reduced chlorophyll a and b contents as well as dry and fresh weights of roots and shoots of the plants in both cultivars. Hamedani cultivar was more sensitive to salinity compared with Yazdi. Inoculation with Sinorhizobium and Bacillus improved plant growth, chlorophylls content and membrane stability both in saline and none-saline conditions compared with the non-inoculated control. The two bacterial strains were synergistic to each other so that co-inoculation was often more effective than single inoculation with Rhizobium or Bacillus. The results suggest that inoculation of the plants with strains of these two bacterial species could help them overcome the salt stress.

Study on phenology of species is of the most important ecological issues, and it can be a foundation for resource management. Phenology recognition of different rangelands species is from important matters in grazing management and sustainable utilization of rangelands forage. Without knowing phenology of different species of a rangeland, it is not possible to determine the grazing season and to manage the livestock grazing. Therefore in order to determine the proper timing of entry and exit of livestock to and from the rangeland, phenology of Atriplex verrucifera as one of the dominant species in the semi-steppe rangelands of Tez Kharab, Urmia and the soil moisture condition were studied. The interpretation of phenological stages was done using climate data. Results showed that from the last days of May to mid June, and from mid September to late October are the best times to start grazing of the Atriplex verrucifera species. Also the soil moisture results showed that livestock entrance to the rangeland in mid May will not cause a problem.

Heavy metal pollution is one of the most significant ecological problems in the whole world. According to the environmental protection agency (EPA), Pb is the most important heavy metal contaminant in the environment. In this study the effects of Pb stress (0, 120, 240, 500, 1000 mM Pb) on 7-day seedlings of Medicago sativa L. were investigated in a hydroponic culture. The results indicated Pb accumulation in roots and aerial parts increased and an increasing trend in total biomass was observed with increase of Pb concentration in medium which reduced later due to increasing Pb accumulation. Compared with control seedlings, increase in the production of MDA and H2O2 which are the indices of oxidative stress, were observed in the seedlings under Pb stress. Moreover, increase in total flavonoids production, and peroxidase activity in roots and shoots of the treated seedlings were observed under Pb stress. Content of total phenolics decreased in roots and increased in shoots comparing with the control.

Soil salinity is one of the most important factors reducing the growth and yield of plants worldwide and determining plant distribution. Antioxidant systems play a crucial role in salt tolerance of plants. In this investigation, the effect of salt stress and its interaction with ascorbic acid on production of H2O2, malondialdehyde, membrane stability and root activities of catalase and peroxidase in Lepidium sativum L. were investigated. The experiment was conducted in a completely randomized design with four replications. Plants were harvested one week after starting treatments. The results showed that salinity increased the amount of H2O2 and malondialdehyde in leaves and roots, and catalase and peroxidase enzymes activities of the roots. Salinity decreased fresh weight of the shoots and roots, and membrane stability of the leaves. This reports shows that exogenous ascorbic acid can alleviate salinity stress effects on plants. As a whole, these data suggest that the ascorbic acid increased the tolerance of Lepidium sativum under salinity stress by overcoming the oxidative effects.

In the present study, the effect of indole acetic acid (IAA) on certain physiological and biochemical parameters in Glycine max (L.) Merr under aluminum chloride (AlCl3) stress was studied. Seeds were sterilized and cultured in petri-dishes. Six-day old seedlings were transferred to pots containing washed sand, and then they were irrigated with Hoagland solution in a growth chamber (with 16 h light per day and day/night temperatures of 25/18). Fourteen day-old plants were treated with different concentrations of AlCl3 (0, 50, 100, 200 and 300 mM) and IAA (0, 50 and 100 mM). Plants were harvested 15 days after treatment. With increase in aluminum concentration, NAR, RLGR, RWC, protein and soluble sugars contents decreased. However, SLA and peroxidase and catalase activities increased. With addition of IAA to culture solutions containing aluminum, the plants showed further decrease in the amount of soluble sugars, but the other parameters were adjusted. Also, with enhancing aluminum concentration in culture solutions with and without IAA, unsoluble sugars increased. Eventually it was found that exogenous indole acetic acid counteracted the deleteriots effects of Al3+ stress and helped plants grow successfully under these unfavorable conditions.

The current investigation concerns the flora of a border mountainous area of Arzaneh, 70 km northwest of Taybad, Khorassan-e Razavi province. A total of 253 plant species belonging to 51 families and 186 genera were identified during 2011 and 2012. Hemicryptophytes (37.5%), therophytes (32.8%), geophytes (14.8%), chamaephytes (9.8%) and phanerophytes (4.7%) constitute the life form spectrum of the study area. From a chorological point of view, Irano-Turanian species were dominant chorotypes (55.9%) and the rest of plants were related to one, two, three or other various phytogeographical regions. Of total identified plants, 31 species are endemic or subendemic of Iran and Flora Iranica area. According to IUCN conservation categories, seven species of the area were classified as vulnerable (VU) and lower risk (LR) in Iranian red data list.

In this study, effect of different concentrations of AgNO3 (4 hours after treatment) and CuSO4 (16 hours after treatment) elicitors were investigated on gene expression of FNS I and antioxidant system in 21-dayCuminum cyminum seedlings. Semi-quantitative study of FNS I gene expression showed a significant increase at 25 and 50 mM Ag+ concentrations rather than the control which had a decrease by the addition of the elicitor to the concentration of up to 100 mM. On the other hand, by the increase in this elicitor concentration, total flavonoid and anthocyanin contents and activity of some antioxidant enzymes as well as total protein content significantly increased compared with the control group. The gene expression was significantly elevated in the treated seedlings by Cu elicitor at 4 and 8 μM treatments while its expression was completely inhibited at 16 μM concentration. In this condition, total flavonoid and anthocyanin contents showed a similar trend and their contents were significantly reduced at 16 μM compared with the control. On the contrary, by increase in the elicitor concentration, the activity of antioxidant enzymes specially catalase and superoxide dismutase, remarkably increased compared with the control, while total protein content drastically decreased. Based on the results, it is deduced that the increase in FNS I gene expression and total flavonoid and anthocyanin contents, were the results of oxidative stress following absorption of these elicitors and activation of plant antioxidant system.