مجله پژوهشهای گیاهی (زیست شناسی ایران)
سال بیست و هفتم شماره 2 (تابستان 1393)

The olive tree (Olea europaea L.)، a representative drought – stress – tolerant plant، is one of the most typical and economically important plant species. As olive cultivars may exhibit different level of drought tolerance، the selection of the most drought – tolerant for cultivation in this area is important. For this purpose، the effect of water deprivation on plant water potential (ψw)، relative water content (RWC)، total soluble protein، proline، malonedialdehyde (MDA)، superoxide dismotase (SOD) and preoxidase enzyme activity in three olive cultivars (Olea europaea L. var ‘Dezfoli’، ‘T2’، ‘Koroneiki’) was studied. Olive trees، grown under field condition in Ahwaz were kept without irrigation for 14 days periods. Changes Of these parameters were measured on 1st، 4th،8th، 13th of the period. Plant water status (ψw)، relative water content (RWC) and total soluble protein of three cultivars decreased with increasing level of drought stress. Proline and MDA content increased with increasing level of drought stress. There was not any significant difference among three cultivars except MDA. Dezfoli showed lower value of MDA content. Significant increasing of SOD and POX activity was observed during the progressive increment of drought stress in all three cultivars. Dezfoli showed higher levels of SOD activity. We concluded higher levels of SOD activity and lower level of MDA in Dezfoli during the development of drought stress indicate this cultivar has more tolerance to oxidative stress due to drought stress than the other cultivars.

Drought stress is one of the most important and most common environmental stresses that limit plant growth in the face. In this path، photosynthesis is main determinant for plant growth and retention ability at environmental stresses is important for preservation of growth stability. for study of the role of stomatal and nonstomatal factors on photosynthesis in safflower (Carthamus tinctorius cv. Sina) in Miyaneh region. A factorial experiment with randomized complete block design (RCDB) and three replications were applied. That at it foliar application of atrazine as a antitranspirant were at 3 phenological stage (steming، flowering and seed filling stages). The antitranspirant application rates were 0 (control)، 80، 120 and 160 gr. ha-1. By the results of analysis of varians (ANOVA) showed that between rates foliar application at all times on physiologic charactristics as photosynthesis rate، transpiration severity، intercellular (Ci)، stomata conductivity، mesophyll conductivity and relative water content (RWC) was significant. This in study foliar application of Atrazine to content 120 gr. ha-1 in flowering time had highest effect on this characters except RWC. The highest RWC were obtained at 120 (gr. ha-1) in steming time. Between rates foliar application of Atrazine than photosynthesis water use efficiency (PWUE) were significant as highest PWUE were obtained at 120 gr. ha-1. Evaluation of characteristic''s correlation showed that there were a positive and significant correlation was found between photosynthesis with characteristics such as transpirant rate، mesophyll conductivity، Ci and stomata conductivity.

To determine the effects of drought stress and nitrogen bio-fertilizer on yield and biochemical indices of medicinal plant of Calendula (Calendula officinalis L.)، an experiment was carry out at research farm of Agriculture in Shahed University. This study was conducted using split plot design based on (RCBD) with three replications in2010-2011. The experiment factors including of different levels of drought stress at forth leaflet stages as main factor (applying soil water potential of 0. 5atm as Control((FC) field capacity)،soil water potential of 3. 5atm as moderate stress، soil water potential of 6. 5atm as highly severe stress،and applying soil water potential of 10atm as severe stress)and levels of nitrogen bio-fertilizer as sub factor were consist of (Control(no applying nitrogen bio fertilizer)، incorporation of 2Liter/ha nitrogen bio fertilizer with water irrigation and inoculation of 2Liter/ha nitrogen bio-fertilizer with seed treatment)، were considered in sub plots. The results showed that drought stress،nitrogen bio-fertilizer and its interaction had significant effect on all characters except for plant height and root weight (P<0. 01). In which with rising of drought stress، length roots (16%)، anthocyanins content (23%)، carotenoids content (71%)، and soluble sugars (36%)، proline content (47%) and photosynthetic pigments content (63%) increased. In that the greatest of flower yield and extract obtained in field capacity irrigation،and so under severe stress flower yield and the extract amount decrease to20%and50%respectively. The most of plant height،flower yield،photosynthesis pigments content،proline content and yield of flower extract were obtained when nitrogen of bio-fertilizer was used in case of seeding. Correlation coefficients showed that between flower yield with biochemical indices there were a meaningful negative correlations (P<0. 01). Overall results showed that Calendula can endure relatively high level of drought with applying 2liter of bio-fertilizer.

To study of diversity of tree and shrub species in relation to topographic factors (elevation، slope، aspect) and some of stand characteristics (canopy density، basal area، diameter، number of dbh classes، number of tree and shrubs)، area about 460 ha of Miantang forests located in north of Ilam province was selected. Then 46 plots 2000m2 were established in accordance to Minimal area method. Variables in each plot were included tree diameter (DBH)، crown maximum and minimum diameter for all trees، number of tree and shrub species، elevation، slope and aspect. Values of diversity indices were computed by PAST software and analyzed with variance analyze، Duncan test and correlation. Totally 11 tree and shrub species were presented in the plots which the most presentation was belong to the Quercus persica. Results showed that elevation، slope and aspect have significantly affected on diversity، richness and evenness of tree and shrub species. The midle elevation classes had the most species richness and diversity. The south aspect had the most richness، diversity and evenness. Also the amount of diversity indices increased with the ascending of the slope، but in over of 60% was decreased. Canopy density and number of tree and shrubs (n/ha) had positive correlation with richness but negative correlation with diversity and evenness.

Salicylic acid as an endogenous signal molecule has been reported to be responsible for inducing abiotic stress tolerance in plant species. In this study، the effect of varying levels of salicylic acid (0، 0. 5 and 1 mM) was studied on growth، mineral uptake، membrane permeability، lipid peroxidation (malondialdehyd) and photosynthetic pigments of salt stressed safflower (Carthamus tinctorius L.) plants. Both tow Cultivars responded similarly to salinity and salicylic acid. Salicylic acid at 0. 5 mM improved plant growth and photosynthetic pigments under saline and non-saline conditions in both cultivars. Salicylic acid also inhibited Na+ accumulation، stimulated K+ and Ca2+ concentrations and decreased lipid peroxidation and ion leakage in salt stressed plants. Higher level of salicylic acid (1 mM) had negative effects on parameters recorded. These results suggested that foliar application of salicylic acid at appropriate concentration can be use as a potential growth regulator to improve plant salinity stress resistance.

Tomato fruit harvested at mature green stage and treated with salicylic acid at different concentration (0، 1 and 2 mM) and analyzed for chilling injury، electrolyte leakage، malondialdehyde، proline and total phenol contents and phospholipase D، lipoxygenase and phenylalanine ammonia-lyase activities during cold storage. Phospholipase D and lipoxygenase activities were significantly reduced by salicylic acid treatment. Compared with the control fruit، salicylic acid treatment alleviated chilling injury، reduced electrolyte leakage، malondialdehyde content and increased proline content. Salicylic acid application had no significant effect on total phenol content but phenylalanine ammonia-lyase activity was significantly reduced in treated fruits. Our result suggest that the reduce activity of PLD and LOX، by salicylic acid may be a chilling tolerance strategy in tomato fruit. Inhibition of PLD and LOX activity during low temperature storage could ameliorate chilling injury and oxidation damage and enhance membrane integrity in tomato fruit.

In order to investigate the effects of plant densities and nitrogen levels on grain yield، rate and effective grain filling period sunflower (Helianthus annus L.) cultivars in Ardabil region، an experiment was carried out as split plot factorial based on randomized complete block design with three replications in experimental field of University of Mohaghegh Ardabili in 2009. Nitrogen fertilizer in three levels (0، 75 and 150 kg N/ha as urea) were assigned to the main plots and the combination of plant density (8، 10 and 12 plant m-2) with two sunflower cultivars (Urofelor and Armavirisky) were factorially assigned to the subplots. The results showed maximum grain weight، rate and effective grain filling period belonged in low plant densities and high nitrogen rates. Means comparison showed that maximum of grain weight were obtained in Armavirisky cultivar × 8 plants/m2 with application of 150 kg N/ha and minimum of it was obtained in Urofelor cultivar × 12 plants/m2 without application of nitrogen fertilizer. The highest grain yield was obtained in application of 150 Kg N. ha-1×Armavirisky cultivar and the least of it was obtained in Urofelor cultivar without nitrogen fertilizer. It seems that in order to increasing the grain yield، rate and effective grain filling period can be suggested that 150 Kg N. ha-1 with Armavirisky cultivar be applied in conditions of Ardabil climate.

Crested wheatgrass (Agropyron desertorum) is a perennial grass that is used for pastures and hay production. This study evaluated total proteins profiles of 180 genotypes of Crested wheatgrass from 18 populations، to determine the extent of genetic diversity. On the basis of SDS-PAGE، 46 reproducible bands in three zones and inter-zones were revealed. Although the number of bands in different populations were comparable but the density of polypeptides in some bands were clearly different in some populations. According these observations five differentiated Protein profiles were recognized and 18 populations classified in 5 groups. Differences among the profiles of different populations were unexpectedly bigger than intra-specific differentiation. There were not found geographic structure among populations with same protein profiles. According present and absent of bands were studied in genetic analysis، populations Hamedan and Ardebil; and Hamedan and Boeenzahra showed highest Nei genetic distances. These populations suggested for hybridization and production new cultivars with higher heterosis. However base on quality and dye density of bands in the protein profiles، pair wise hybridization among different populations of each of five groups were suggested. These results suggested that the genetic base of cultivated crested wheatgrass should be broadened by involving diverse parents in the breeding program. Expansion of the genetic base for crested wheatgrass breeding might be accomplished by systematic use of germplasm that differs in protein profiles and has better quantitative traits.

Salinity has been identified as one of the most pervasive environmental hazards، limiting crop production mostly in arid regions of the world such as Iran. In this research، two cultivar canola seeds (H420، H308) were grown hydroponically and seedlings exposed to different concentrations of NaCl (0، 50، 100، 150 and 200 mM) Changes in fresh and dry weights of roots and shoots، chlorophyll content، membrane electrolyte leakage and relative water content (RWC)، in response to salt stress these were evaluated in 20-old days plants of two cultivars. Results showed that increasing of salinity concentration caused a reduction in fresh and dry weights of shoot and root، chlorophyll content، relative water content (RWC) but increased electrolyte leakage and these responses were more severe in H420. These results suggest that maintenance of relative water content in more resistant cultivar (H308) combined to higher chlorophyll content and more membrane integrity were considered as part of the mechanisms for resistance to salt stress in H308 cultivar.

Periwinkle (Catharanthus roseus (L.) G. Don)، a medicinal plant، which economiclly is highly valued because of its anti-cancer lalkaloids of vincristine and vinblastine. Since the availability of nitrogen (N) is expected to play an important role in the biosynthesis and accumulation of alkaloids in plants، the effect of N fertilization on the content of alkaloids of periwinkle was studied. the four levels of 0، 100، 150، 200 kg/ha N fertilization in a bulok completely randomized design with three replications. N fertilization significantly increased the content of alkaloids in leaves. This study showed that by increasing N fertilization dry weight increased. The highest level of alkaloid vincristine was in the 0 kg/ha of N fertilization and the highest level alkaloid vinblastine was in the 200 kg/ha of N fertilization.

Salinity stress is the most important osmotic stress that limits growth and production of crop via changing ion and osmotic balance. In order to investigation of salinity stress effects on germination، vegetative and some germination indices an experiment conducted by factorial based on randomized completely block designs with 4 replications in 2010 in department of agriculture of Urmia Payame Nor. The factors were 8 genotypes (Shahriar، Sardari، Sardari 39، Sardari 101، Zarin، Arvand، fgs and Azar 2 and 6 level of salinity (0 -2-4-8-12-16) ds/m from Nacl. The results showed that different levels of salinity had significantly effects on germination percent، root dry weight، seedling dry weight، plantlet dry weight، germination rate، germination uniformity، stem length، stress tolerance index and root length. With increasing salinity stress all of traits decreased، so the highest obtained from control treatment and the lowest obtained from salinity level of 16 ds/m. The genotypes respond differently to salinity levels. It seems genotypes of Zarin، Arvand and Sardari have more tolerance to salinity conditions. Genotypes of Sardari 101 and Azar 2 were sensitive to salinity stress.

Low temperature is one of the most important stress factors limiting the growth and productivity of canola. To alleviate or prevent low temperature-induced oxidative injury، plants have evolved mechanisms to scavenge these toxic reactive species. Recently، many different compounds are applied to minimize the harmful effects of low temperature. In this study effect of foliar application of salicylic acid has been studied on some biochemical properties of two canola cultivars with different cold resistant [RGS (Spring canola and sensitive to cold) and LICORD (Winter canola and resistant to cold)]. Salicylic acid was sprayed at four levels، including 0، 100، 200 and 400 µM. Leaf samples were collected 24 h after spraying. The effects of salicylic acid and cold stress on the lipid peroxidation، activities of antioxidants enzymes including superoxide dismutase، peroxidase، catalase، polyphenol oxidase، protein content and proline in leaves of canola plants were investigated. The results showed that salicylic acid increased significantly activity of antioxidant enzymes including superoxide dismutase and peroxidase، content of protein and proline but decreased significantly lipid peroxidation and catalase activity in both cultivars. Sprayed with salicylic acid increased the seed yield. Maximum shoot dry weight was in resistance cultivar، as well. However، in some cases، higher concentrations led to a decrease in the measured traits of both cultivars. The results show that enzyme activity in both cultivars were different. Except CAT and PPO، in other cases، salicylic acid enhanced the activity of these enzymes.

In this study، effect of salicylic acid on delaying senescence in rose flowers was investigated. Rose flowers cv. Yellow Island was pre-treated with different concentrations of salicylic acid (SA) during 18 hours. The greatest delay in senescence was obtained with 150 mg L-1 SA، as compared to control was increased nearly twice. Application of 150 mg L-1 SA caused to retard degradation of protein over 8 days vase life. SA suppressed increasing proline up to 4 days، thereafter، its content in SA- treaded and control was the same. Moreover، 150 mg L-1 SA retarded lipid peroxidation and delayed flowers senescence. The results suggested that SA as a preservative solution resulted to stabilize membrane and maintain protein content، delay senescence in cut rose flowers.

In natural ecosystems، a part of species composition is stored in the soil seed bank as a community of living seeds. Identifying these species pools is important for vegetation conservation and restoration. This study aimed to identify the seed bank size and composition in a part of mountain grassland of Alborz in Mazandaran province. Seed bank was sampled from two soil depths (0-5 and 5-10 cm) and then emerging seedlings were identified and counted in a glasshouse. Results showed that 49 species were in the soil seed bank، of which only 30 species were common between the soil seed bank and standing vegetation. The most abundant species in the seed bank were Carex sp.، Cynodon dactylon، Stachys byzanthina، Dactylis glomerata and Stellaria media comprising 50% of the total. According to plant functional groups، Gramineae، Cyperaceae، Labiatae، hemi-cryptophytes، forbs and perennials were dominant in the seed bank. The majority of seedlings originated from the upper soil layer (0-5 cm)، with 70% of the total germination. Moreover، the upper soil layer significantly had greater species richness and diversity than that in lower soil depth. Also، greater species richness and diversity was found in above-ground vegetation than that in the soil seed bank.

Freydoonkenar international complex wetland is one of 22 Iranian wetlands registered in Ramsar convention. It is a habitat for large varieties of rare immigrant birds particularly the critically endangered species، Siberian Crane. The surface of the area is 5427 ha and is located near to Caspian Sea. It comprises different types of natural and artificial habitats including wildlife refuge، pools، rice fields and lowland forest patches. Due to the fact that the knowledge of flora and fauna of any area is essential for further evaluation of environment and ecological potential of that area، a total of 248 vascular plant species belonging to 176 genera and 73 families were examined in the area. Poaceaea، Asteraceae، Papilionaceae، Polygonaceae and Rosaceae are the richeset plant families، respectively. Therophytes are the most abundant life forms and pluriregional plants possess the highest proportion among all plants studied in the area. All plants in the area belong to three distinct habitats، marginal or ruderal، aquatic and forest، which contain 56، 24، 20 percent of all plants. One of the most prominent features of the wetland is the occurrence of thermophil and endemic lowland Caspian forest in the area.