فصلنامه گیاه و زیست بوم
پیاپی 30 (بهار 1391)

Trifolieae is one of the largest tribe in Fabaceae family with genera that have trifoliate leaves. There are large morphological similarities among the genera of this tribe, particularly in calyx and corolla characters. To determining the phonetic similarities between these species, 32 characters in 50 species have been studied by numerical taxonomy. A cluster analysis based on UPGMA method determined two main groups. Melilotus species were placed in separate group based on style and seed characters. Second cluster divided into three other genera. Trifolium species showed one homogene subgroup and some of the Trigonella species have been grouped between Medicago species. Type of leaflets, stipulates shape, style and legume characters were an important factors to separate those species.

Hymenochaetaceae are wood inhabiting and causes of white rot. They are recognizable by drown Basidiocarp, Seta and no Cystidia in Hymenium. This study carried out in area about 7290.1 hectares of Neka forest area by forest surveying method. 8 species of fungi belong to family of Hymenochaetaceae have been colleted on 5 hosts; consist of one ectomycorrhizae, 4 saprophytes and 3 parasite. A review on previous reports showed that Coltricia perennis is new for Iranian mycoflora. In respect of fungi host associations for Iran 2 species are new.

Mediterranean Hackberry (Celtis australis L.) is one of the Mediterranean species in Hyrcanian Forest. Hard seed coat causes physical dormancy in this species. In order to breaking dormancy and increasing germination, the seeds of C. australis were exposed gibberllic acid with 100 and 200 ppm (for 24 hours) and sulfuric acid for 15 and 30 min. Then seeds were stratified in moist sand and maintained in refrigerator (4c) for six mounts. After eighteen weeks, it was revealed that, gibberllic acid provided greater germination percent, mean germination, germination value, germination speed and germination energy than sulfuric acid. Gibberllic acid with concentration of 100 ppm caused the highest germination (63%) whereas germination provided by control and sulfuric acid treatments, did not proceed 35% and 20% respectively. It can be proposed that this species can used in next researches with sulfuric acid for shorter time, gibberllic acid 100 ppm for longer time, hot water and distilled water treatments.

Verticillium wilt is one of the most important vascular diseases of olive. It has always being considered to survey its various aspects such as distribution, biology, pathogenicity and management. In order to investigate host-pathogen interaction, this research was carried out to study histopathology of olive (cultivar Zard) inoculated by Verticillium dahliae. Rootdipping method for 30 min was used for inoculation of the seedlings by spore suspension with concentration 109 spore/ml. 4-12 weeks after inoculation, with occurrence of wilt symptoms; transversal sections were prepared from various parts of the stem and root. Then, very thin transversal sections were prepared and after different stages of staining, microscopic slides were prepared. The results of microscopic investigations showed that the causal agent of Verticillium wilt has caused disorders in physiology and flowing of vascular sap through spreading into vessels, obstruction of xylem vessels and their destruction. The results also showed that seedlings with producing tylose caused obstruction of vessels and prevented spreading of pathogen. Pathogenicity and defensive mechanisms associated with host-pathogen interaction and their roles at susceptibility rate of olive to Verticillium wilt had been discussed in this research.

In order to investigate and compare the cultivars of the Berseem clover from the point of yield quantitative and qualitative forage yield, a field study was carried out in 2008-2009, in the form of random complete blocks design using time dependent split plot method (cultivar as the main plot and different harvest stages as sub plot) using thirteen variants in four times and three cuttings at Seed and Plant improvement institute in Karaj. The result of variance analysis for mean cuttings showed that from the point of quantitative traits in fresh yield and dry yield and from the point of qualitative traits in percentage of protein, the effect of harvest by cultivar were significant at the level of one percent. Also the result of mean comparison showed that the highest fresh yield and dry yield and protein percentage, were obtained as 27.38 and 6.68 ton per hectare and 27.63 percent respectively for cultivar Elitt-2 in mean three cultivar. Therefore based on the results, Elitt-2 and Tolidi-e-dezfoul cultivars are appropriate and can be recommended for Karaj metrological conditions compare to other cultivars.

In the same weather, existence of different soil types causes change or loss of plant community. Accordingly the full knowledge about soil condition as an important environmental factor for better understanding of plant habitat is necessary factor. In this study the relationships between two species of Agropyron trichophorum and Astragalus verus Olivier and soil in the rangelands of Karchambuy was investigated and in continue, the most important soil characteristics affecting the separation and determination of habitat was also examined. For this purpose, after visiting of the study area, nine study sites were selected based on vegetation map. Then vegetation and soil factors in these places were separately studied. For investigation of relationship between canopy cover of study species and soil factors, the researchers used multiple analyses of CCA and PCA. Results showed that soil depth, nitrogen, clay, organic matter, sand, pH and amount of lime factors were important factors affecting the establishment and growth of Agropyron trichophorum species. For Astragalus verus Olivier species amount of lime, salinity, gravel and P and saturation percentage factors are also considered as key elements in the distribution of this species. Finally, the study sites were classified into three groups. In this matter, based on Anova analysis, soil texture had a deniable role in classifying.

In this research, habitat of Thymus kotschyanus was studied ecologically. This species hasspread into an area of 4600 ha within Polur in Mazandaran province and the relation between T. kotschyanus with some environmental factors (soil characteristics, slope, aspect and elevation) and the most important effective factors was investigated. Sampling method was randomized-systematic and vegetation types were studied by physiognomic- floristicmethod in the field. Within each unit along three 100 meter transect 10 plots (1m2) established along each transect in 10 meter distances. Three soil samples in each area collected in 0-30 cm and parameters such as N, P, organic material, pH, EC and texture were determined. To compare the mean canopy cover and density of T. kotschyanus between elevation and slop classes and different aspects interactions, multi-way analysis of variance was used and to compare means of interior classes of factors and existence significant difference among them, one-way analysis of variance and homogeneity Duncan test with software SPSS was employed. Results showed that topographic factors and their interaction effects and soil characteristics in different aspects had significant effect on cover percentage and density of T. kotschyanus. The maximum of canopy cover percentage and density of T. kotschyanus respectively related to western and eastern aspect, slope class of >45 and elevation of 2200-2500 m, changes of canopy cover had the most relationship to OC, N, pH and P. changes of density had the most relationship to EC, litter and stone.

I order to study the effect of salinity stress on germination indices of six promising wheat lines; an experiment was conducted in 2009 at the Jiroft Agriculture Research Center. A factorial layout with a completely randomized design with three replication was used. Salinity stress levels (0, 3, 6, 9, 12, 15, ds/m), and wheat lines (Chamran, Darab 2, ERSal 81- 59, ER-Salt- 83-6, ER-Salt- 83-12, ER-Salt- 81-6) were considered as A and B factors, respectively. Result showed that the increase in salinity level 0 to 15 ds/m, significantly reduced all germination indices. Lines were significantly different in respect to germination indices. ER-Salt-83-12 and ER-Salt-83-6 had the highest and lowest germination percentage, germination rate, root dry weight and lowest and highest EC, respectively. Based on Germination Stress Index, ER-Salt-83-12 and ER-Salt-83-6 lines had highest and lowest resistance to salinity, respectively.

In this research the effect of different lead concentrations (0, 0.25, 0.5, 0.75, 1, 1.5 and 2mM) and salicylic acid with concentrations (5, 10μM) on content of protein and soluble and insoluble sugar cubes (starch) of Brassica napus L. Cv. Okapi in hydroponic culture were studied. The growing period was 10 days and statistical analysis was done with SPSS soft war and test of Duncan. The result was shown that with increasing the concentration of Pb the amount of soluble and insoluble sugars in root and shoot was significantly decreased (P<0.01) and the amount of protein with increasing lead concentration in root increased and in shoot was decreased. Increasing amount of soluble and insoluble sugar cubes in root and shoot in these plants which were under treatment both lead and salicylic acid show the role of salicylic acid in increasing tolerance of plants to lead stress. The reduction of the amount of Protein in roots and increasing in shoots under lead and salicylic acid treatments indicated of reduction in damages that caused by oxidative stress in these plants.