جستجوی مقالات مرتبط با کلیدواژه "morphology" در نشریات گروه "اکولوژی"

Recognition of the influential environmental factors in natural ecosystems plays a significant role in the success of the life cycle of existing plant species. This study was conducted to investigate some of the dominant ecological features affecting the morphological alterationsof the reproductive organs of Gundelia tournefortii L. in 11 major habitats of this species in the central Zagros region, Iran. Two influential features of vegetation (canopy cover percentage and density per unit area), 14 environmental factors in three groups of physiography, soil and climate along with nine morphological features related to reproductive organs of G. tournefortii L. (inflorescence and seed) were assessed in its major habitats, following the relevant assessment methods. Results were analyzed using Pearson's correlation test, Principal Component Analysis (PCA) and cluster analysis. The environmental factors, including absorbable potassium, soil shear strength, electrical conductivity, length of dry period, average annual temperature, average number of frost days and average altitude were the most important dominant ecological features in the morphological variations of plant reproductive organs.  Identifying the relationship between vegetation and the affecting ecological features plays  a very efficient role in achieving accurate information sources in the management of natural habitats.

Tamarix sp. Shrub species are extended in steppe and salt marsh areas. These species have adapted to the most hard climatic conditions. Therefore, it is distributed in the driest regions of Iran. The native plants are rarely used for landscape in Iran. So, identifying native plants that has the potential to be ornamental, in addition to the attractiveness of landscape can prevent soil erosion. In this study, 60 Tamarix genotypes from 11 regions in Markazi province were studied during spring and summer and subsequently morphological characteristics were evaluated based on quantitative and qualitative (as codding) traits. Inflorescence length on current shoots, number of flower clusters per shoot, flower cluster length, current shoot color, annual shoot diameter, flower color, tree growth habit, main branch diameter, main branch length, branch density, leaves density, branch flexibility, etc. were studied. The best time for measurement of traits was in late April to early June. Based on the results, there was an excessive diversity between the quantitative and qualitative studied characteristics, which reflected the rich germplasm of this province. In order to choosing native plants in the urban landscape, one should look for species with low water requirements, less maintenance and high ornamental potential. The maximum positive correlation was obtained between tree growth vigor and tree density and the maximum negative correlation was observed between flower cluster diameter and annual stem color. Khosbijan genotype could be introduced as a shrub with ornamental use in landscape due to their appropriate morphological traits such as the longest inflorescence, upright tree form, high density of foliage and brunches.

Therefore, due to the increasing concerns about the destructive environmental effects of high consumption of nitrogen fertilizers and also the high economic cost of supplying these fertilizers, the present study was done to evaluate the growth, development and yield of three common maize cultivars in Response to different amounts of nitrogen in semi-arid climatic conditions of Kerman province .

A two-year experiment was laid out as a randomized complete block design with factorial arrangement of treatments and three replications during 2014 and 2015 growing seasons at Kerman province in Iran. Four nitrogen rates (0 (control), 92, 220 and 368 kg ha-1) were applied to three maize hybrids (KSC 704, Maxima and TWC 604).

Results showed both hybrid and nitrogen had significant (P<0.01) effect on morphology, biological and grain yield of maize. We found the significant yield benefits of KSC 704 and Maxima compared to TWC 604 under N stress as well as potential conditions. However, the grain yield of all hybrids was lower in 2015 than 2014 which was a consequence of depletion of soil N as a result of previous maize on one side and light texture of the soil (consisting about 85% sand) on the other side which led to high N leaching from the soil. The highest and lowest values for grain yield was observed at 368 kg N ha-1 (12359.3 kg ha-1) in 2014 and 0 kg N ha-1 in 2015 (640 kg ha-1) respectively.

Iranian mangrove forests provides valuable information to prevent genetic erosion in the gene pool of these ecosystems. The aim of this study was to investigate the genetic diversity among mangrove forests located in four different regions of Iran, based on morphological characteristics and microsatellite markers. Cluster analysis of molecular data, using neighbor joining algorithm classified the 60 mangrove trees, sampled from different coastal areas, into four groups. Analysis of molecular variance showed that the majority (77%) of the variance explained by among-population variation and the highest values of genetic diversity parameters including number of effective alleles, Shannon’s information index, and Nei’s genetic diversity were obtained for the Qeshm population, indicating that region is the most diverse population among all the studied populations. Baced on the morphological analyses significant differences were observed between all populations in terms of height, diameter at breast height, collar diameter, leaf size, pneumatophore length and pneumatophore diameter. The present study, provides useful information about genetic diversity of mangrove habitats which can be used in evolutionary studies and conservation efforts for these valuable plant ecosystems.

Water and soil salinity is one of the important factors limiting the development of green space in arid regions of Iran .In this study, some morpho-physiological characteristics of Morus alba, Ailanthus altissima and Cupressus Sempervirens seedlings to water salinity stress in Sokan nursery of Semnan were investigated.Eight levels of water salinity treatment were considered as 0, 2, 4, 6, 8, 10, 12 and 14 ds/m and irrigation was performed twice a week in the amount of four liters from July to September.During the experiment, morphological characteristics such as height and collar diameter of seedling were measured every 15 days after the start of treatment.At the end of the experiment, leaf samples of seedlings were collected and transferred to laboratory and dry and fresh weight of roots, shoots, leaves, Rwc, amount of Na+ and K+ leaf with flammimetric method, Ca+2 and Mg+2 leaf was measured by the complexometry method, the leaf nitrogen level using titration and phosphorous leaf method by ammonium molybdate in the laboratory.The results showed that the traits of seedling height, collar diameter, number of leaves, fresh and dry roots and shoots and, Rwc, content of Na+, Ca+2, P, Mg+2, N and K+ of leaf in salinity and species treatments were significant at 1% percent level. However, the interaction effect of species and salinity were not significant for all the above traits at the level of 1% and for the trait diameter of the collar and the elements nitrogen and potassium of leaf were not significant. Results of comparison of means showed that with increasing salinity, the amount of leaf sodium increased, but others factor decreased. The critical point for the changes in the above traits was often at salinity 6 to 8 dS/m and above, which indicates that the studied tree species can tolerate salinity up to this level.In comparison, in terms of all seedling height, collar diameter, number of leaves, fresh and dry weight of roots and shoots and, Rwc, the amount of Na+, Ca+2, P, Mg+2, N and K+ in the leaves among the three species, respectively, Morus alba and Ailanthus altissima then Cupressus Sempervirens showed the highest salinity resistance.

In order to investigate the effect of sowing date and plant density on morphology, phenology and yield variables of 704, 540 and 500 maize hybrids, a factorial experiment was carried out based on complete randomized block design with four replications. In this research, row space was fixed at 75cm and inter row spacing was 12, 15 and 18cm that create 111500, 89000 and 74000 plants per hectare, respectively. In this study, the highest number of kernel rows per ear, with 18. rows, was obtained by hybrid 500. Whereas, the highest number of kernels per row, with 24.4 kernels, was produced by hybrid 704. But, among studied hybrids, the number of kernel per ear was not significant. The results also showed that the highest forage yield, with 48.1 ton per hectare, was obtained by hybrid 704 and hybrids 540 and 500 with 42.6 and 40.8 ton forage yield per hectare ranked next, respectively. High performance of hybrid 704 depends on its high biomass production so that the dry weight of hybrid 704 was 118.9 gram per plant that had significantly differences compared to other hybrids. With increasing of plant density, forage yield per plant was decreased significantly and forage yield per unit area was increased. The highest forage yield per unit area, with 46.3 ton per hectare, was acquired from 12cm row spacing. The study of phonological traits demonstrated that in Bonab region only hybrid 500 could reach to maturity stage (dough stage) for harvest. With respect to high quality of maize forage for silage at dough stage, the hybrid 500 for is suitable and if the purpose is grazing, sown of hybrid 704 with highest density is recommended.