نشریه خشک بوم
سال چهارم شماره 1 (بهار و تابستان 1393)

This study was conducted to evaluate the effects of water stress on dry matter and carbohydrate accumulation as well as nutrient status of Salvia macrosiphon. A completely randomized design with three replications was used in an experimental greenhouse at Yazd University. Different levels of drought stress including 100، 75، 50 and 25% of field capacity were considered as treatments. Results showed that absorption of potassium، calcium، magnesium، nitrogen، phosphorus، sodium، zinc، iron and copper as well as، dry matter accumulation were significantly affected by drought stress. Result also indicated that water stress has significant (P≤0. 01) effect on soluble carbohydrate. Mean comparison test showed that the dry matter accumulation rate (total dry weight of root and shoot dry weight) and concentration of potassium، calcium، magnesium، nitrogen and phosphorus decreased by increasing drought stress، whereas concentration of sodium، zinc، iron، copper and solution carbohydrate was increased in response to deficiency of water.

In arid and semi-arid regions، evaporation from the soil surface represents the major water balance component that causes losses of water. Urban landscape (particularly grass cover) consumes a large amount of water in urban areas. Using mulch is a proper method to reduce the cost and volume of irrigation. This field experiment was completely randomized blocks design with eight treatments and three replications. The experiment consisted of wood، sand and tire-chips mulches of 2. 5 and 5 cm thickness. Three plots were planted with grass، three plots had no mulch or grass cover (control) and the remaining 18 plots were covered with mulches. In each plot، Chrysanthemum (Chrysanthemum Pompona) was planted and conducted during 70 days. Results indicated that the treatment with a thickness of 5 cm of sand mulch had the best performance on saving water. Then sandy mulch with a thickness of 2. 5 cm، the tire-chips mulch with a thickness of 2. 5 cm، wood-chips mulch with a thickness of 2. 5 cm، the tire-chips mulch with a thickness of 5 cm and wood-chips mulch with a thickness of 5 cm had the best performance on reducing water consumption، respectively. The plots of grass and control consumed the greatest volume of water during the experimental period. Water consumption from the soil covered by woody chips mulch (5 cm) and sandy mulch (5 cm) decreased 50% and 87%، respectively compared to the grass cover. Also، the sand and woody chips mulch with a thickness of 5 cm decreased the water consumption volume، 26% and 78%، respectively compared to the control plot (no mulch).

Salinity is a major abiotic factor that limits growth and yields of most plant. It has been known that endo-mycorrhiza fungi are able to reduce this restriction on some plants in saline conditions. In this study، effects of two two species of mycorrhiza fungi Glomus mosseae and G. intraradices inoculation were examined on NaCl salt tolerance (0. 5 as control، 6 and 12 dSm-1) in two safflower cultivars (Goldasht and Padide cultivars). Four days old safflower seedlings were grown in pots containing a mixture of perlite and coco peat، and mycorrhizal inoculum (50 spores per gram of mixture) for two months in controlled conditions. The experiment was conducted as factorial based on completly randomized design with three replications. Results showed that salinity reduced plant height، root length، dry weight of stem، leaf and roots and plant pigments contents، which indicated damages due to salt stress. Plant height، root length، dry weight of stem، leaf and roots and plant pigments contents were higher in the inoculated plants than non-inoculated those. Under control conditions، the best vegetative growth was observed in Goldasht cultivar inoculated with Glomus intraradices; while under 6 dS m-1 conditions، the best performance was obtained in Padide inoculated with Glomusmosseae. However، at 12 dS m-1 treatments use of both funkgi species had similar and positive effect on vegetative growth. Generally، it can be concluded that the inoculation of safflower with mycorrhiza fungi would mitigate the negative effects of salinity on plant growth.

Indian Gerbil (Tatera indica Hardwicke، 1807) is from Muridae family and Gerbillinae subfamily. Habitat range of this species involves arid and semi -arid areas. The species has been listed in IUCN (2013) at the lowest level of concern (Lc). This study was conducted using logistic regression approach and all effective factors on habitat suitability of T. indica were identified in Sistan region. Field studies were conducted at five different sampling stations in Zabol during spring 2013. Seven environmental variables including the percentage of vegetation cover، soil، gravel cover (<0/2 mm diameter)، percentage of cover of Tamarix species (Haloxylon sp)، percentage of coverage of Desmatchia-Bipinata، cover of Salsola aucheri and distance from water resources in 60 plots of presence/absence were performed and analyzed using binary logistic regression method. Results showed that variables of soil cover، cover gravel and coverage percentage of Desmatchia-Bipinata and distance from water resources have important role (P< 0. 05) in relation to the distribution of T. indica in Sistan.

This study was conducted to investigate effects of different osmotic potential (0، -1، -2. 16، -4، -5. 4 and -10. 9) induced by NaCl and Polyethylene Glycol-6000 (PEG) as salinity and drought stress respectively، on germination and early growth of Thymbra spicata L. The experimental design was completely randomized with three replications in which arranged as factorial. The experiment was carried out in a germinator (25°C) with 20 seeds in each Petridish. After 2 weeks germination percentage، germination rate، length of stem and root، dry and wet weight of stem and root were measured. Results showed increasing osmotic potentials decreased significantly rate and percentage of germination. Highest amounts of these indices were measured in control and lowest in osmotic potential of -10. 4 bar. In similar osmotic potential، the effect of osmotic potential induced by PEG6000 was more than the effects of NaCl. Increasing of osmotic potential decreased length، wet and dry weight of root. In similar osmotic potential the effect of osmotic potential induced by NaCl was more than the effects of PEG6000 on mentioned indexes. Results also showed the high osmotic potential in both treatments affected negatively on length، wet and dry weight of stem. These indices affected more by PEG6000 than NaCl. Finally، the differences between two treatments in all measured germination indices were discussed.

In this research، the effects of Prosopis juliflora on annual natural vegetation، soil properties and farm land in Sirik area in the east of Minab، Hormozgan province was carried out in 2001 and 2005. Since natural ecosystems and their stability، especially natural vegetation are a national wealth، it is necessary to evaluate effects of this invasive species. In this research، at two different times (2001 and 2005) percent age of annual vegetation cover including grasses and forbs were measured with plots of 0. 5 m2 under canopy cover of P. juliflora and open area، in the study area. Soil samples were taken at 0-15 and 15-30 centimeter depths and in laboratory soil properties measured. Then، using Mini-Tab softwar، soil and vegetation parameters، in plots sampled، under and outside the canopy cover of this species، were compared with T tests. Results showed that percent of cover of annual vegetation including grasses، forbs and total of percent cover under canopy and open area in years when rainfall is high، have significant difference between percent cover under canopy and open area. Results also show that، there is significant difference in some soil properties such as pH، Electrical conductivity and organic carbon in depth of 0-15 centimeter. Statistical comparison showed pH is decreased in canopy cover and some soil properties such as organic carbon has increased significantly in canopy cover. Despite of the P. juliflora effects on natural environment، because of the natural regeneration، these species regenerate in agricultural lands and gardens with seeds which are transported by water، domestic animals، and wildlife. P. juliflora makes density thicket and reduce table of groundwater. P. juliflora، also، causes undesirable effects on domestic animals، therefore، farmers and ranchers encounter big problem.

Playa is an important landforms in desert environments and covers an extensive area in this type of ecosystem. Playa landform is composed of different geomorphic surfaces. After orogenic activities and evaporation of water bodies remained from Thetis Sea، playa was formed and various evaporite minerals were precipitated. Minerals with lower solubility precipitated in upper parts were the origin of minerals for lower positions. Kheirabad saline-gypsiferous playa in Kerman Province was selected to study physicochemical، clay mineralogy، and micromorphological properties. Clay flat، puffy ground clay flat، wet zone and salt crust are among geomorphic surfaces identified by field studies and Google Earth images in Kheirabad playa. Electrical conductivity at non-saline clay flats varied between 2. 8 to 32. 2 dS/m. Smectite، illite، palygorskite and kaolinite were detected in this geomorphic surface. Euhedral gypsum crystals and calcite coatings were observed in gypsic and calcic horizons of this position، respectively. Electrical conductivity in saline clay flats varied between 33. 5 to 160 dS/m. Lenticular and interlocked plates of gypsum were among secondary gypsum crystals identified in this geomorphic surface using micromorphology. Maximum EC (314 dS/m) was investigated in puffy ground clay flat which is attributed to capillary movement of saline groundwater. Illite، palygorskite، smectite، and kaolinite clay minerals together with calciticcrystalitic b fabric were found in wet zone geomorphic surface. Electrical conductivity and percentage and size of gypsum crystals increased from upslope positions toward the center of the playa، but no such a trend was found for clay minerals.

Caper (Capparis spinosa var. parviflora) is a winter-deciduous perennial small shrub growing in hot and dry climates. This is well-known as a multipurpose plant. Regarding to its germination difficulties، this study investigates the seed germination of caper under potassium nitrate (KNo3) treatment using the halopriming technique. For this purpose، four concentration levels (0، 50، 100 and 200 mM) and four time levels (0، 24، 48، 72 hours) with three replications were considered as factorial experiment based on the completely randomized design. Some traits including germination percentage، germination speed، mean time of germination، seed vigority index، stem length and root length as well as fresh and dry weight of stem and root were measured. Results show that the halopriming technique significantly affects the germination characteristics of caper seeds، whereas the greatest germination percentage and vigour index were found in treatment of 200 mM-48 hr.، the greatest germination speed in 200 mM-72 hr.، and the greatest fresh weight of stem and root in 200 mM-24 and 72 hr. Results suggest that the halopriming technique can be introduced as a new approach to improve germination of this species، particularly in afforestation activities of aridlands in southern Iran.