فرزاد پارسادوست

Marl lands are very sensitive to erosion in arid and semi-arid regions and are one of the most important sources of sediment production. Research has shown that there is a relationship between the geological characteristics of marls and different forms of erosion. In some marl formations, rangeland plant species have grown and stabilized which causes erosion control and soil stability. In order to better understand the status of these ecosystems, this study was conducted to identify the established plant species on marl lands and investigate the relationship between vegetation and physical and chemical properties of marl soil in three types of surface, rill and gully erosion in Semirom region.

Semirom is one of the marl regions that was selected for the current study in the classification and determination of marl erodibility indices of Isfahan province. In order to evaluate the erosion condition in three forms of surface, rill and gully erosion, BLM (Bureau of Land Management) form was completed in the same marl units and areas without vegetation cover. In the next step, three soil samples were collected from 0-20 cm depth in three repetitions in marl units including three forms of erosion. Physical and chemical soil properties including texture, EC, N, P, K, SAR, OC, CEC, CaSO4, pH, T.N.V and CaCO3 were measured. For vegetation studies in the study area, after preparing the floristic list of plant species, vegetation characteristics including canopy cover percentage and density per plant species, as well as the percentage of gravel and litter were measured and recorded. The statistical analysis of the data was done as a completely random design using SAS software and the averages of soil properties were compared according to the Least Significant Difference (LSD). Correlation analysis between soil and vegetation characteristics was also done by R statistical software.

Results and Discussion:
The results showed that in terms of erodibility, Marl lands with vegetation cover, had a better condition than without vegetation. The soil in the gully erosion was in better conditions in terms of nitrogen, phosphorus and organic matter and had better vegetation than the other two types of erosion. The results of correlation between physical and chemical soil properties and vegetation showed that the canopy cover factor was 95% and 86% correlated with the percentage of gypsum and the percentage of sand, respectively. The dominant species which showed the most protection capacity against erosion in surface, Rill and Gully erosions were Astragallus cephalantus, Cousinia cylindracea and Elymus gentry with 34.2, 33.3 and 22.05 percent of the highest combination of density and canopy cover, respectively. In terms of growth form, in all three types of erosion, forbs had the highest percentage of density and canopy cover.

The results of current research could be considered as a novel achievement in order to prevent soil erosion through establish appropriate species in marl lands with similar climatic conditions.

Marl formations are one of the most important sources of sediment production in arid and semi-arid regions. Marl lands are highly susceptible to erosion, causing an increase in drinking water treatment costs, reducing the useful life of dams, and significantly decreasing the permeability of floodwater spreading areas.  Different forms of erosion have been shown to have a relationship with the geological characteristics of marls, as evidenced by research. The results of the study of the effect of the physical and chemical properties of marl sediments on erosion in Latshore-Pakdasht showed that the amount of Na+, SO4-2 and silt in the marl lands increased, while the percentage of clay decreased from surface to gully erosion. The form and intensity of water erosion are greatly influenced by changes in soil texture. Gully erosion can be developed by increasing the amount of sand compared to the finer particles of silt and clay. Despite the difficulty of vegetation establishment on marl lands, in some areas, surprisingly, a relatively dense cover of rangeland species can be observed, which can cause erosion control and soil stability. The results of the systematic survey of plant species and their protective role in the marl lands of Ilam, Yazd and Gilan provinces all indicate that rangeland species are one of the most effective and suitable methods to prevent soil erosion by creating a stable vegetation cover on marl formations. The relationship between the physical and chemical properties of the soil with vegetation characteristics including distribution, canopy cover and density is inevitable. In the marl lands of Borujen, the research revealed that vegetation type named Astragalus brachycalyx-Daphne mucronata-Cirsium bracteosum can be established in neutral marl lands, with medium CaCO3 content and minimal presence of Na+ and Cl-. On the other hand, the vegetation type named Astragalus susianus-Daphne mucronata-Amygdalus elaeagnifolia can be established in alkaline and calcareous marl lands with very high amounts of Cl- and can be effective in controlling water erosion in marl lands. Considering arid and desert climate and the occurrence of surface, rill and gully erosions in the marl lands of Kashan region, as well as the importance of protecting and controlling erosion in the marl formations of the region and the lack of detailed vegetation studies in this region, accurate identification of the vegetation of the marl lands and prioritizing native and resistant plant species is necessary for the rehabilitation management of vegetation and biological protection of soil in these areas. Therefore, the aim of the current research is to identify rangeland species and investigate their role in erosion control in the selected marl formations in Kashan. In addition, the physical and chemical soil parameters of marl lands and the vegetation characteristics of plant species in different types of erosion are investigated.

Kashan is one of the marl regions chosen for the current study on the classification and determination of marl erodibility indices in Isfahan province. Two vegetation types named Anabasis setifera-Artemisia sieberi-Salsola tomentosa and Pteropyrum aucheri-Pteropyrum olivieri-Artemisia sieberi have been identified in the selected Marl lands of Kashan. In order to evaluate the erosion condition in three erosion forms of surface, rill and gully, BLM (Bureau of Land Management) form was completed in the same marl units and control areas without vegetation cover. In the next step, three soil samples were collected from 0-20 cm depth in three repetitions in marl units including three forms of erosion. The physical and chemical soil properties including texture, EC, N, P, SAR, OC, CEC, CaSO4 and CaCO3 were measured. For vegetation studies in the study area, after preparing the floristic list of plant species, three 100 m transects were established in a random-systematic method. In each transect 10 plots of 2 m2 were placed and vegetation characteristics including canopy cover percentage and density per plant species, as well as the percentage of gravel and litter were measured and recorded. The statistical analysis of the data was done as a completely random design using SAS software, and the averages of soil properties were compared according to the Least Significant Difference (LSD). Correlation analysis between soil and vegetation characteristics was done by SPSS statistical software.

The results showed that in terms of erodibility, Marl lands with vegetation cover had a better condition than those without vegetation. Based on analysis of variance, the physical and chemical parameters of soil and vegetation characteristics in three types of erosion had significant differences at level of 1% and 5%. In gully erosion, the amount of N, P, SAR, OC, litter and canopy cover were in better conditions compared to other types of erosion. The results of correlation between soil properties and vegetation characteristics showed that the canopy cover had significant correlation with the percentage of sand (r=0.92) and a negative correlation with the amount of CaCO3 at (r=0.97). In terms of the type of dominant plant species, in surface erosion Ephedra strobilacea Bunge. with canopy cover of 1.71%, in rill erosion Anabaisis setifera Moq. with canopy cover of 1.24% and in gully erosion Artemisia sieberi Besser. with canopy cover of 12.3% were identified as the most suitable species for soil protection. In all three types of erosion, bushes had the highest percentage of density in terms of growth form. In surface erosion and gully erosion, shrubs occupied the highest percentage of canopy cover.  In gully erosion, due to better conditions of soil moisture and organic matter, bushes and shrubs were successful in competition with annual and herbaceous plants. They established well due to deep and extensive root system. The results of current research could be considered as a novel achievement in order to prevent soil erosion through establish appropriate species in marl lands with similar climatic conditions.

Contamination with heavy metals such as leads resulting from human catastrophic excavation activities is one of the serious soil problems in arid and semi-arid region. So, remediation of these kinds of contaminations is one of priorites to protect the soil of these areas. In soil and sediment environments, the potential bioavailability and mobility of metals are predominantly regulated by adsorption/desorption reactions at the mineral-water interface. Although numerous studies have been devoted to understanding the adsorption of metals onto minerals, less is known about desorption processes, especially their kinetics, under the influence of organic ligands. In this study, desorption of Pb from montmorillonite (MMT) was studied as effected by biodegradable chelating ligands, i.e. methylglycine diacetic acid (MGDA) and glutamic-N,Ndiaceticacid (GLDA), at two concentrations (0.25 and 1.0 mM) were compared with that of ethylenediaminetetraaceticacid (EDTA). The results showed that Pb desorption was rapid, reaching equilibrium in a relatively short time (within 3 h). The degree of Pb desorption was proven to be governed by the presence and concentration of the chelating agents. The capacity of the chalants for removing Pb from MMT was in the order EDTA>MGDA>GLDA. Approximately 12%, 19%, and 23% of the sorbed Pb was desorbed by 0.25 mM of GLDA, MGDA, and EDTA, respectively. The corresponding desorptions in the presence of 1.00 mM of the same ligands were 47%, 59%, and 93%, respectively. Therefore, it can be predicted that the presence of biodegradable ligands, i.e. GLDA and MGDA compared to EDTA will create less mobility of Pb in the environment and consequently we will have less pollution in soil and water environments. Owing to soil alkalinity in arid and semi-arid region, it seems that using biodegradable ligands can desorbtion of lead from soil, minimizing the risk of under water contamination.

Although phosphorus owns the lowest amount between essential elements in the plant, but due to its important role in the vital processes of the plant, its supply during the growing period of wheat is essential. This study was conducted to investigate the response of wheat to the use of phosphorus in different stages of its growth and in different conditions of water salinity in pots and in soilless culture system. This experiment were performed in the factorial experiment in a completely randomized design with three factors of irrigation water quality (2 and 8 dS / m), phosphorus concentration (30 and 45 mg/l) and the stage of growth of wheat that receives phosphorus (seedling stage, tillering stage, elongation stage of Stem, flowering and seed filling) and three replications. Plants were harvested at the end of the physiological maturation phase. Root and shoot dry weight, shoot phosphorus concentration, chlorophyll and catalase and peroxidase enzymes were measured. Increased salinity decreased 48% phosphorus concentration of shoots, 40% dry weight of roots and shoots and 100 and 50% increase of catalase and peroxidase, respectively. Increasing the concentration of phosphorus from 30 to 45 mg/l caused 10 and 36% increase in dry weight of roots and shoots, respectively. The highest amount of chlorophyll, root and shoot dry weight due to the use of phosphorus was observed in the stem elongation stage and the lowest values were related to the application of phosphorus in the seedling stage. Based on this research, it seems that fertilization is necessary during the wheat growth period, especially in the stage of elongation of the stem and flowering.

One of the most important problems in arid and semi-arid regions is the salinity of water and soil. poplars, which are native to Iran, are found in many climates. In crossbreeding programs, the transfer of salinity traits and resistance to salinity stress from P.euphratica, and on the other hand, the transfer of good quality trait form of the trunk and high growth of spruce, bruised are special importance. For this purpose  this study was conducted to evaluate the rate of resistance to salinity stress and growth of four poplar colonies (Populus alba 58.57, Populus alba 44.9, Populus euphratica, P. euphratica x P. alba 44/9) in the form of complete randomized block design with three replications and was performed for 3 years in Rudasht salinity research station. For this purpose, P.euphratica, P.alba and Hybrid of P.euphratica trees were cut down and planted. The physiological characteristics of the leaf, including proline, sugar, chlorophyll a and b, carotenoid, total protein, peroxidase value and relative moisture content were measured according to standard methods. The results of the physiological characteristics of the leaf showed that poplar colonies had significant differences in terms of proline, total protein and relative humidity percentage but carotenoids, chlorophyll a and b, total chlorophyll and chlorophyll a / b ratio did not show a statistically significant difference. However, the highest amount of chlorophyll a, b and total chlorophyll was obtained in the leaf of hybrid clone. However, the highest amount of chlorophyll a, b and total chlorophyll in the leaf was related to hybrid clone and were equal to 0.76, 0.36 and 1.12 mgg-1 dry matter, respectively. Growth characteristics of seedlings including living percentage, diameter, height, leaf area, leaf thickness, leaf area and leaf dry matter percentage were also measured. The results of analysis of variance of vegetative characteristics of poplar colonies showed that the coefficients of percentage of survival, diameter and height are statistically significant at the level of 5%. The average comparison test showed that P.euphratica with 93% and Colon Hybrid with 85% had the highest survival rate compared to bruised colonies. In addition, P.euphratica species with a diameter growth of 3.8 cm and a height of 160 cm had the highest amount of vegetative growth. In general, according to the vegetative and physiological characteristics of seedlings, Pede species and hybrid clone can be recommended under salinity stress.

Evaluation of chemical and biological indicators of soil in different land uses could be helpful in sustainable range management, preventing degradation of soil quality trend. This study was conducted in Friedan in Isfahan province in 2010 to compare chemical and biological indicators in three land uses (rangeland, degraded dry land and dry land), during two growing seasons (May and September) in three slopes (0-10, 10-20, 20-30 %). Nitrogen, phosphorus, potassium, organic matter, cation exchange capacity and microbial soil respiration were measured. Results showed that all measured characteristics except potassium decreased over an increase in the slope. Maximum values of phosphorus, organic matters, cation exchange capacity and soil respiration were obtained in pasture (28.4 mg/kg, 0.62%, 20.38 cmol/kg, 33.2 mgC/day, respectively)but potassium maximum rate was seen in dry land form (406.8 mg/kg).The effect of season on all measured parameters was significant except for N, while the highest amounts of phosphorus, potassium, cation exchange capacity and soil respiration (28.7 mg/kg, 377.3 mg/kg, 19.6 cmol/kg and 25.9 mgC/day, respectively) were seen in May and the highest organic matter rate (0.68%)in September. The results of this study showed that an increase in the slope, poor range management, and the end of the growing season could be major factors degrading the soil quality indices and soil productivity.

Nowadays, heavy metal contaminated soils is one of the most important concerns of the world and cleaning these soils with minimum environmental damage is necessary especially in urban and agricultural regions through advanced biological methods. Phytoremdiation is one of the modern technologies that could be used in large scale with minimum damage to environment. High concentration of cadmium, as an environmental pollutant, could be harmful for human and animals. Regarding to this reason, a study was carried out on 11 plant species in Irankouh region at three sites including three levels of high, medium and low cadmium contamination. The bioaccumulation of cadmium in shoots and roots of plants, and translocation factor were measured. According to the results, Astragalus glaucanthus, Ebenus estellata and Acantholimon sp. showed the highest values of cadmium concentration (1.40, 1.53 and 1.97 mg/kg dry matter), and also the highest translocation factor (2.09, 1.37 and 12.6), respectively. Because of the high values of biomass and bioaccumulation, these three plants are recommended for phytoremediation of cadmium-contaminated soils under the same conditions.

In order to study the effects of irrigation water salinity on the yield and yield components of three commercial sunflower hybrids, this experiment was carried out in a randomized complete block design and three replications in Rodasht Agricultural Research Station during three years. The main factors of irrigation water quality were at 4 levels i. e. 2, 5, 8, and 11 dS m-1 and the sub main factors were sunflower hybrids Allstar, Haysan 33, and Azargol. Statistical analysis results showed that salinity and high concentration of some minerals, especially sodium ions, in irrigation water affected the diameter, total oil yieldو and water use efficiency was significant at 1% level, while the effects on plant height, stem diameter, seed weight, grain yield, water use, and oil percent was significant at 5% level. Statistical analysis showed that the effects of hybrids on the diameter, oil yield, plant height, stem diameter, weight of 100 seeds, and water use efficiency were significant at the 1% level, and on yield at 5% level. In terms of performance, hybrids Haysan 33, Azargol, and Allstar had, respectively, the highest seed yield, oil yield, and water use efficiency.

Rangelands represents the largest land resource in the world and therefore are important from economy and environmental perspectives. Improper use of natural resources including soil causes its degradation and results in severe soil erosion. Therefore a study was conducted in Friedan in Isfahan province in 2010. The objective of this study was to compare selected soil physical indices in a rangeland with good vegetation cover (>20%), dry land forming and a degraded dry land form which is used in three slop (0-10, 10-20, 20-30). Land was selected in such a way that changes them for the past 10 years and the geology and vegetation types and manages the same. The composite surface (0-15 cm) soil samples to determine physical properties of soil such as particle density, bulk density and water disperse clay and hardness of surface soil. A rainfall simulator was run for 40 minutes whit 20+5 rainfall intensity to stimulate the amount of sediment, runoff and sediment concentration. Data was analysis with SAS and compared by Lsd test. The highest porosity was observed for pasture with good vegetation. Maximum gradient of 30 to 20 percent in the runoff for degraded dry land form in September 2197 to the amount of cubic centimeters per square meter was observed. The largest amount of sediment in dry land form and steep for 30 to 20 percent in the September to 15.7 grams per square meter was observed. The highest sediment concentration 20.3 grams per liter and a 30-20 percent dip in August was the season. Poor management and non-normative caused the reduce of soil productivity in the long term.