Fire is one of the incorporate vegetation management practices for grasslands and semi-arid rangelands. It may affect symbiotic relationship between range plants and mycorrhiza. Accordingly, this research was aimed to investigate the effects of a spring prescribed fire on the symbiotic relationships between mycorrhiza and 6 plant species. The study was conducted in a semi-arid steppe rangeland called Dehbar, Torghabeh in Mashhad, Iran. A prescribed fire was applied on 20th April 2015. Soil and plant samples were taken one month later. Colonisation and spore density were measured on the root of 6 different species. Spring fires significantly increased fungi spores in the rhizosphere of all plant species with the highest and lowest frequencies (42 and 24 per gram dry soil) obtained for Pimpinella tragium and Artemisia aucheri, respectively. Fire effects on colonization varied from high to no effect ranges. The increases in the mycorrhiza propagules after a prescribed burning during the growth season might be due to a sudden increase of nutrients from plant ashes. Although the studied plant species were different in terms of morphology (canopy and root type), phenology and life form (geophyte, perennial grasses and shrubs), the spring fire increased the colonization rate for plant species that had just started vegetative plant growth (Stipa barbata, Artemisia aucheri and Pimpinella tragium) but it had no effects regarding the plant species (Poa bulbosa, Agropyron trichophorum andAstragalus gossypinus) that were fully grown at the time of burning and/or had terminated seasonal growth period at the time of soil sampling. Therefore, in terms of plant-mycorrhizal symbiosis, a prescribed spring fire might increase the competitive advantage of perennial late season species as compared to annual early season species which are mostly ephemeral or invasive plants. تفاصيل المقالة

The most important and sensitive level in the modification of rangelands surrounding the mine is the initial seedling establishment of plants, which often faces failure due to adverse environmental conditions, poor soil nutrients, disturbance of soil different layers and its instability and unstable soil around the mines. New methods of rangeland improvement using biological and non-biological materials (zeolite, superabsorbent and mycorrhiza) and strategies may help to establish plants in the soil around abandoned mines. This research aims to investigate the possibility of improving the primary establishment and growth of Agropyron desertorum in mine areas infected with heavy metals. Initially, seeds were sown in paper pots. After two months, pots were treated with Glomus intraradices, zeolite and superabsorbent along with control. Pots were transplanted in the field in semi-arid lands of East Mashhad cement factory using a completely randomized block design with four replicates in 2016. The plants were irrigated only once for the establishment. Data were collected about establishment rate, plant height, the percentage of mycorrhiza root inoculation and shoot, root and total dry weight. The results showed that the application of mycorrhiza, zeolite and superabsorbent increased plant establishment rate (50, 42 and 25%) and root dry weight (62, 72 and 15%) higher than that for control. Application of the mycorrhiza and zeolite treatments increased plant height (44 and 42%), aboveground dry biomass (51 and 61%) and total dry matter biomass (54 and 66%) higher than that for control treatment. The results showed that mycorrhiza and zeolite treatments had the greatest effect on increasing the initial establishment and improving the growth characteristics of A. desertorum. It was concluded that using zeolite and Glomus intraradices may be effective method for the initial establishment of plants in areas contaminated with heavy metals in the mining area in the semi-arid regions. تفاصيل المقالة

Colocynth (Citrullus colocynthis) is one of the major medicinal plants, naturally growing in deserts of Middle East and North Africa. Extending cultivation of this species is useful for sand dune fixation and livelihood of the local inhabitants. In spite of numerous studies on seed germination, there are still debates on the best methods of breaking seed dormancy for colocynth. Moreover, seed morphology, phonological stages and habitat conditions of this species is almost unravelled. This study was conducted in 2016-2020 at Gonabad desert, Iran. We established five line transects of 200 m and five plots of 4×4 m, and vegetation parameters, phenology and root morphology, soil charactristics of colocynth were measured. The pH varied between 7.0-7.5 in bare soil and 8.0-8.1 under the canopy of colocynth habitat. The soil of study area was classified as slightly saline. Two weeks pre-chilling at 4°C and night -day temperature range from 25-40°C significantly increased seed germination. In our study area, colocynth was detected as a perennial forb with long and ligneous roots (more than120 cm). Its vegetative growth starts in middle of May, seed ripening and shedding occur in October and November. Average fruit volume was 2.62 cm3 and seed number counted in each fruit varied between 250 to 420 by the length of 4-7 and 2-4 mm width. Big size fruits contained the highest seed numbers. The best harvesting time in terms of both economic value and seed viability is ripening of fruits. تفاصيل المقالة

Growth season rain pulses affect biological and physiological activities of wild plants in arid and semi-arid regions. Despite of numerous reports on the effects of rain pulses on plant physiological indices, there is little information on how rain pulses may affect secondary metabolites of medicinal plants. Caper (Capparis spinosa L.) plays a critical role on soil conservation and economy of arid and sub-tropical inhabitants. Accordingly, present research was conducted to investigate the physiological and phytochemical responses of caper to a growth season rainfall in its natural habitat in Mazdavand, Sarakhs, Iran. Leaf samples (4 replicates) were taken 2, 4, 7 and 10 days after a natural rain event (10 mm) in 17 May 2018. Results showed increase of antioxidant enzymes (catalase and ascorbate peroxidase activity by 77 and 34 %, respectively) and decrease (23%) in proline content by the day after the rain pulse, whereas, photosynthetic pigments were not affected by soil moisture changes. Total alkaloid content was higher (16%) in vegetative than reproductive phase. From the secondary metabolites and 14 major phytochemical compounds detected in leaf extract, phenol content was reduced whereas alkaloid content increased by decreasing soil moisture during the days after rainfall. In conclusions, the phytochemical compounds showed contrasting (increase or decrease) responses to the soil moisture pulse and inter-pulse conditions. These results indicate the best time of leaf harvest to achieve highest concentrations of specific secondary metabolites after the growth season rain pulses. تفاصيل المقالة

Khaje Kalat woody rangelands, located in northeastern Iran, represent one of the few remaining Sicilian pistachio rangelands worldwide. Understanding the ecological processes shaping pistachio communities is crucial for effective management and restoration efforts. This study aimed to investigate the impact of abiotic environmental factors on Pistacia vera L. density, a research study was conducted during 2018-2019. And 162 quadrats (25 m2 each) were established across three geological formations, two aspects (northern vs. southern), and three classes of Terrain Niche Index (TNI). The two-way analysis of variance (ANOVA) was employed to analyze the impact of geological formation, topographic attributes, and soil parameters on pistachio density. Significant findings (p<0.05) underscore the pronounced influence of geological formation, TNI, and their interactions on pistachio density. These findings showed distinct patterns across formations and elevations. Moreover, an analysis of soil parameters highlights the pivotal roles of phosphorus and geological formations in influencing pistachio density. Notable associations between phosphorus levels and density emerged, along with substantial variations in soil properties among different formations. While recognizing the significance of soil fertility, particularly in nutrient-rich lowlands, the study suggests that it may not be the primary limiting factor for mature pistachio trees. However, the presence of such nutrient-rich lowlands may potentially hinder pistachio establishment. In conclusion, these insights underscore the importance of analytical ecosystem management for preserving and restoring Pistacia vera rangelands effectively. تفاصيل المقالة

Seedling establishment is a crucial stage in the restoration of degraded rangelands. The effects of sowing dates and bio-fertilizers on the growth and establishment of Thymus daenensis Celak (native) and Thymus vulgaris L. (introduced) were studied over two growth seasons at Islamic Azad University, Borujerd branch, Lorestan, Iran. The treatments consisted of four bio-fertilizers treatments i.e., mycorrhiza fungi, nitrogen-fixing free-living bacteria (NFB), phosphate solubilizing bacteria (PSB), and a control group, two species of Thymus sp. and two transplantation dates (November 2017 and March 2018) were also included. PSB and NFB (50 mm/lit of dissolved water) as well as mycorrhiza were applied twice: once during seed sowing in pots and again after transplanting the seedlings in the field. The results demonstrated that T. vulgaris exhibited superior performance (ranging from 31.8% to 51%) in various plant traits such as height, canopy cover, leaf area, dry leaf weight, dry shoot weight, aerial dry weight, root dry weight, shoot-to-root ratio, and root volume compared to T. daenensis. The transplantation date did not significantly affect seedling survival rate and shoot growth. However, seedlings transplanted in November had a higher root-to-shoot ratio (0.94), root dry weight (3.48 mm), root volume (3.56 m3), main root length, and mycorrhiza colonization (11.4%). In exceptionally wet year in in 2018, T. vulgaris performed better than T. daenensis. However, we anticipate T. daenensis to outperform T. vulgaris during normal and dry years, particularly with the application of PSB biofertilizer in its root medium. We recommend simultaneous comparisons of plant growth and thymol concentration under various cultivation and/or biofertilizer treatments on Thymus species in future studies. تفاصيل المقالة