دکتر علی اشرف امیری نژاد

Phytoremediation is an important method for refining heavy metals, but the main limitation is the low bioavailability of the metals. Chelating agents, by releasing heavy metals from the soil solid phase, can increase their uptake by the plants. In this research, the effects of some chelating agents on the phytoremediation of Vicia faba in a calcareous soil contaminated with Cd were investigated. A factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of Razi University. The factors included Cd at four levels (0, 5, 10, and 15 mg kg-1 soil as CdCl2), and three chelating agents including ethylene di-amine tetra acetic acid (EDTA), citric acid (CA), and oxalic acid (OA), at two levels (4 and 8 mmol kg-1). The results showed that the highest Cd concentration in the root and shoot (39.90 and 27 mg kg-1, respectively) was obtained at 15 mg kg-1 of Cd and 8 mmol kg-1 of EDTA, CA, and OA. The highest values of transfer factor (0.67) and biological accumulation factor (5.65) were obtained at the highest level of Cd pollution and 8 mmol kg-1 of chelating agents. This indicates that firstly, cadmium was mainly accumulated in the root and was less transferred to the shoot. Secondly, it shows the potential of bean in phytoremediation and Cd uptake. Also, the amounts of the measured factors with citric and oxalic acid were not much different from EDTA, and therefore, these two environmentally friendly natural chelating agents could be used instead of EDTA.

The use of chelating agents has been introduced as a suitable strategy to reduce the detrimental effect of heavy metals in plants. To investigate the impacts of aspartic acid (AA) and glutamic acid (GA) in alleviating lead (Pb) stress in lemongrass (Dracocephalum ruyschiana), a factorial experiment was conducted based on a completely randomized design with three replications, in the greenhouse of Razi University, in 2023. The treatments included Pb contamination at three levels (0, 150, and 300 mg.kg-1 soil as Pb (NO3)2), aspartic acid (AA) at three levels (0, 100, and 200 mM), and glutamic acid (GA) at three levels (0, 100, and 200 mM). Both acids were used as foliar application. The results showed that the highest proline content (8.12 μmol.g-1) and soluble sugars (2.94 mg.g-1) were obtained in 300 mg.kg-1 of Pb, without AA and GA, which shows an increase of 320% and 285%, respectively, compared to the control (without Pb and chelating agents). Also, the highest amount of shoot and root dry weights, plant height, root length, and volume were found in the treatment of 200 mM of AA and GA, and without Pb. In general, AA and GA, as foliar spray could significantly reduce the adverse effects of Pb on the crop growth characteristics. Thus, application of these chelating agents is a convenient method to diminish the effect of Pb stress on lemongrass.

Heavy metals are non-biodegradable and persistent in nature thereby disrupting the environment and causing huge health threats to humans. Cadmium (Cd) is a toxic heavy metal that enters the environment through various anthropogenic sources, and inhibits plant growth and development. Cadmium toxicity may result from disturbance in plant metabolism as a consequence of disturbance in the uptake and translocation of mineral nutrients. The use of plant hormones has been introduced as a simple and suitable strategy to reduce the effect of heavy metals in plants. A new method for reducing the effect of cadmium on plants is the use of growth regulators such as salicylic acid (SA). Tomato (Lycopersicon esculentum) is an important vegetable that is rich in minerals, various vitamins and antioxidant compounds. Since the cultivation of tomatoe, as an important and highly productive crop, is very common in many parts of Iran, there is a possibility of contamination of the soil under cultivation with cadmium. Therefore, the present study was conducted to evaluate the the effects of foliar spraying of salicylic acid on reducing Cd-induced stress in tomato (Lycopersicon esculentum L.).

A factorial experiment based on a complete randomized design with three replications was conducted in a greenhouse of Razi University. Factors included Cd at three levels (0, 15 and 30 mg kg-1 as Cd(NO3)2) and SA at three levels (0, 250, and 500 μM). The solutions containing Cd-(NO3)2 were sprayed uniformly on the sub-samples separated from the original soil sample according to the desired concentrations. The samples were kept moist for 30 days at moisture conditions close to field capacity. At the four-leaf stage, SA solutions were sprayed three times on the foliage of the plants, until the beginning of flowering. After harvesting, some characteristics including soluble sugars and proline contents, plant height, dry weights of shoots and roots, and root volume and length were determined. All plant parameters were then averaged for each pot. Also, Cd concentrations in extracts obtained from the digestion of leaf tissues, were measured by Varian AA220 atomic absorption spectrophotometer. The analysis of variance (ANOVA) and comparison of means (Duncan's multiple range test) were performed using SPSS-16 software.

The results revealed that Cd stress reduced all plant characteristics, such as plant height, root volume and root length, as well as, dry weights of shoots and roots, and elevated leaf Cd concentration, proline content and soluble sugars in tomato. However, the SA application resulted in improvements in growth parameters. Also, the results showed that the interaction effects of Cd and SA on the most growth characteristics such as plant length, shoot and root dry weights, stem diameter, leaf area, and proline content, soluble sugars and Cd concentration were significant (P <0.01). The highest amount of soluble sugars (0.48 mg kg-1), proline content (26.3 mmol g-1) and Cd concentration (0.685 mg) were obtained in 30 mg kg-1 of Cd and 0 μM SA. Also, the highest amount of soluble sugars (0.53 mg kg-1), plant length (44.6 cm), root length (19.6 cm), shoot dry weight (7.51 g), and leaf area (268.2 cm2) were found in the treatment of 500 μM SA and 0 mg kg-1 Cd.

The application of salicylic acid effectively increased the all measured growth parameters, including plant biomass, and total root volume. Cd stress reduced growth indices and, increased proline content and soluble sugars in tomato. Also, it seems that under Cd-induced stress, SA is an effective approach for improving crop growth by increasing plant resistance. In general, the application of appropriate concentration of salicylic acid (500 μM), as a plant hormone, is an effective, simple and low-cost strategy to reduce the adverse effects of Cd (30 mg kg-1 soil) stress in tomato.

Some organic modifiers can be used to reduce the effects of alkalinity on plants. In this research, the effects of simultaneous application of biochar in the soil and foliar spraying with humic acid on the reduction of alkalinity stress in basil (Ocimum basilicum L.) were investigated. A factorial experiment was conducted based on a completely randomized design with three replications. The factors included alkalinity stress at three levels (0, 50, and 100 mM as NaHCO3 with irrigation water), biochar (at three levels of 0, 1.5, and 3% by weight mixed with soil) and humic acid at three levels (0, 150, and 300 mg/L as foliar spray). The results showed that the interaction effect of alkalinity, biochar and humic acid on most of the growth characteristics as well as the amounts of proline, soluble sugars and plant pigments were significant (P≤0.01). The highest shoot and root dry weight (0.88 and 0.39 g, respectively), shoot height (23.5 cm), root length (19.5 cm) and relative water content (86.4 %) were obtained with application of 3% of biochar and 300 mg/L of humic acid, without alkalinity. Also, the highest amount of proline (3.13 μmol/g) and soluble sugars (6.08 mg/g) were found under severe alkalinity stress (100 mM of NaHCO3), without the use of biochar and humic acid. In general, the simultaneous use of biochar and humic acid is a simple, suitable and cheap method to reduce the adverse effects of alkaline stress in basil.

Drought is one of the most common and important factors limiting production in arid and semi-arid regions. Some organic amendments can be used to reduce the effects of drought on plants. The aim of this study was to investigate the effect of municipal waste compost and farmyard manure on the growth characteristics of basil (Ocimum basilicum L) under water deficit. A factorial experiment was conducted based on a completely randomized design with three replications in 2022 in the greenhouse of Razi University, Kermanshah. The factors included water deficit (at three levels of 50, 75 and 100 % of field capacity (FC), farmyard manure (at three levels of 15, 30 and 45 ton/ha) and municipal waste compost (at three levels of 15, 30 and 45 ton/ha). For the manure, the treatment without manure and also for the compost, the treatment without compost is considered as the control. The results showed that the interaction effect of compost and farmyard manure under water deficit on most of the growth characteristics as well as the amounts of proline, soluble sugars and plant pigments were significant (P≤0.01). The highest shoot and root dry weight (2.1 and 1.7 g, respectively), shoot height (24.1 cm), leaf area (75.5 cm2) and relative water content (29.3 %) were obtained with application of 45 tons/ha of compost, 45 tons/ha of manure and FC. Also, the highest amount of proline (9.78 μmol/g) and soluble sugars (1.06 mg/g) were found under 50% of FC, without the use of compost and manure. In general, the simultaneous use of municipal waste compost and farmyard manure is a simple, suitable and cheap strategy to reduce the effects of water deficit in basil.

The use of modifiers can reduce the effects of environmental stress in plants. The aim of this study was to investigate the effect of salicylic acid and zeolite in reducing alkalinity stress in black seed (Nigella sativa L.). A factorial experiment was conducted based on a completely randomized design with three replications in 2022 in the greenhouse of Razi university, Kermanshah. The factors included alkalinity stress (at three levels of 0, 50 and 100 mM as NaHCO3), salicylic acid (at three levels of 0, 0.5 and 1 mM), and zeolite (at three levels of 0, 0.25 and 0.5 % by weight). The results showed that the effects of salicylic acid and zeolite on most of the plant growth characteristics under alkalinity stress were significant (P ≤ 0.01). The highest amount of proline (12.65 μmol/g) and soluble sugars (0.2 mg/g) were obtained under severe alkalinity stress without the use of salicylic acid and zeolite. Also, the highest shoot height (24.6 cm), root length (19.5 cm), shoot dry mass (0.78 g) and leaf area (22.47 cm2) were obtained without alkalinity and with application of 1 mM salicylic acid and 0.5 % zeolite. In general, the use of salicylic acid, as a plant hormone, and zeolite, as a soil amendment, is a suitable and cheap strategy to reduce the effects of alkalinity stress in black seed.

The use of plant hormones has been introduced as a simple and suitable strategy to reduce the adverse effect of heavy metals in plants. To investigate the effect of salicylic acid (SA) in reducing lead (Pb) stress in tomato (Lycopersicon esculentum L.), a factorial experiment was conducted based on completely randomized design with three replications in the greenhouse of Razi University. Factors included soil Pb contamination at three levels (0, 150 and 300 mg kg-1 soil as Pb(NO3)2) and SA at three levels (0, 250 and 500 μM). Results showed that the highest proline content (23.4 mmol g-1) and Pb concentration (4.26 mg kg-1) were obtained in 300 mg kg-1 of Pb and 0 μM SA, which shows an increase of 303 and 387%, respectively, compared to the control (without Pb and SA). Also, the highest amount of soluble sugars (0.48 mg kg-1), plant height (43.5 cm), root length (18.3 cm/plant), shoot dry weight (7.48 g/plant), and leaf area (263.1 cm2/plant) were found in the treatment of 500 μM SA and 0 mg kg-1 Pb. In general, the results showed that the application of SA, as a plant hormone, is a simple and convenient method to reduce the adverse effects of Pb stress in tomato.

In precision agriculture, a productivity rating system is a significant tool to quantitatively assess soil quality. An experiment was conducted in Bilavar, Kermanshah to evaluate the spatial variability of physical indicators of soil quality of a rapeseed (Brassica napus) field. Spatial variability analysis of soil physical properties measured on a rectangular grid (100 m×100 m) was carried out using a geostatistical analyst extension of Arc-GIS software. Five physical soil quality indicators including bulk density (BD), non-capillary porosity (NCP), field saturated hydraulic conductivity (Ks), available water retention capacity (AWC), and organic carbon (OC) were determined. The physical rating index (PRI) at each sampling point was determined by multiplying the rating values for all five parameters. Results revealed that major ranges of semivariogram for Ks and AWC varied between 137-145 m and for BD, OC, and NCP they were relatively long (161-205 m). Clay and NCP showed moderate spatial dependence (0.68 and 0.28, respectively) whereas the rest of the parameters showed weak spatial dependence. Also, the correlation between PRI and the biological yield of rapeseed was fairly good (R2=0.68). Investigation of zoning maps of soil physical properties showed an increase in BD and a decrease in AWC and NCP parameters depending on changes in soil texture and organic matter content in some parts of the field. In general, the PRI index is an important tool in the quantitative assessment of soil physical conditions, and based on it and zoning maps can improve the physical quality of soil in agricultural fields.

Industrial development has resulted in higher soils pollution with heavy metals. Plants which are subjected to heavy metals may severely lose their yield capabilities. Applying improving compounds in the soil is a new method to reduce effects of heavy metals on plants growth. Biochar as a carbon rich source and salicylic acid as an important plant hormone, are two main compounds to alleviate heavy metals stresses in plants. These are the cost-effective and environmentally friendly substances for increasing the resistance of plants. Lead (Pb), as a common and extremely poisonous element in polluted soils, can be accumulated due to its non-biodegradability nature. When Pb content in plants reaches a toxic level, it can inhibit plant growth by reducing enzyme activities and photosynthesis and changing mineral nutrients balance. However, with regard to the program of expanding the area under cultivation of medicinal plants, including thyme, there is a possibility of contamination of soils in the vicinity of industrial centers and roads with lead. Therefore, the present study was conducted to evaluate the effects of salicylic acid as a plant growth stimulant and biochar made of rapeseed wastes, as a stable organic compound, on alleviation of Pb-induced stress in thyme (Thymus vulgaris L.). 

In order to investigate the effects of salicylic acid (SA) and biochar (BC) on reducing Pb stress in thyme (Thymus vulgaris L.), a factorial experiment was conducted based on a completely randomized design with three replications in the greenhouse of Razi University. The factors included Pb at three levels (0, 150, and 300 mg/kg as Pb(NO3)2), SA at three levels (0, 150, and 300 μM) and BC at three levels (0, 1 and 3% by weight). To apply the Pb treatments, the soil samples of each pot (8 kg) were sprayed with Pb(NO3)2 solutions, 4 weeks before planting, according to the contamination levels. Then, BC treatments were performed by mixing it with the soil samples. In each pot, four thyme seedlings were planted. At four-leaf stage, SA solutions were sprayed three times on foliage of the thyme plants , until the beginning of flowering. After harvesting, some characteristics of aerial and root parts of thyme, including soluble sugars and proline contents, plant height, dry weights of shoots and roots, root volume and root length were determined. All plant parameters were then averaged for each pot. Also, Pb concentrations in extracts obtained from digestion of leaf tissues, were measured by Varian AA220 atomic absorption spectrophotometer. The analysis of variance (ANOVA) and comparison of means (Duncan's multiple range test) were performed using SPSS-16 software.

The results revealed that Pb stress reduced all plant characteristics, such as plant height, root volume and root length, as well as, dry weights of shoots and roots, and elevated leaf Pb concentration, proline content and soluble sugars in thyme. However, BC application resulted in improvements in growth parameters. The positive effect of BC was further enhanced when SA was sprayed onto the foliage of the thyme plants. The interaction effects of SA, BC and Pb treatments on the growth parameters of thyme, i.e, shoot dry weight, root volume, Pb concentration, soluble sugars and proline contents were significant (P < 0.01). In other words, SA and BC treatments moderated the negative effects of Pb on the growth traits. The highest Pb concentration (4.83 mg) and proline content (37.8 μmol/g) were obtained in 300 μg/kg of Pb, and SA and BC controls. Also, the highest concentration of soluble sugars (0.46 mg/kg) was found at 300 mg/kg of Pb, 300 μM SA and BC control.

Our results indicated the positive effects of SA and BC treatments on the growth parameters, such as; shoot and root dry weights in thyme plants, especially under Pb stress. In other words, Pb stress, while reducing all growth characteristics, increased proline content and soluble sugars in thyme. In general, it seems that under Pb stress, treatment of thyme with SA (as a plant growth regulator) and BC (as an organic matter with high viability in the soil) is a simple and appropriate method in order to increase the plant's resistance and reduce the effects of Pb toxicity on the overall growth of thyme.

Amending soil with biochar (BC) and foliar application of salicylic acid (SA) are two new methods for reducing the effects of heavy metals on plant growth. To evaluate the effects of SA and BC made from rapeseed wastes on alleviation of lead (Pb) stress in salvia (Salvia afficinalis L.), a factorial experiment was conducted in a complete randomized design with three replications in the greenhouse. The factors included Pb concentration at three levels (0, 150 and 300 mg/kg as Pb(NO3)2), BC at three levels (0, 1 and 3% by weight) and SA at three levels (0, 150, and 300 μM). The results showed that Pb stress reduced all growth characteristics of salvia, but the treatments interactions on the proline content, soluble sugars and Pb concentration and the most growth characteristics such as leaf area ad root volume were significant (p < 0.01). The highest proline content (25.7 mmol/g) and Pb concentration (4.36 mg/kg) were obtained at 300 μg/kg of Pb, and BC and SA controls. Also, the highest concentration of soluble sugars (0.41 mg/kg) was found at 300 mg/kg of Pb, 300 μM SA and BC control. In general, although Pb stress had a decreasing effect on most morphological characteristics of salvia, but simultaneous application of BC and SA, as a simple and low-cost strategy, could reduce the negative effects of Pb by increasing proline and soluble sugars in the plant.

In this research, the interaction of Pb stress, salicylic acid (SA) and biochar (BC) on growth parameters of basil crop (Ocimum basilicum L.) were investigated. This experiment was conducted as a factorial, based on a complete randomized design with three replications in greenhouse of Razi University. Treatments included canola biochar at three levels (0, 1 and 3% by weight), SA at three levels (0, 100 and 200 μM) and Pb at three levels (0, 100 and 200 mg/kg Pb(NO3)2). Results showed that the highest plant height, stem diameter, fresh and dry plant weight, leaf area, fresh and dry root weight, and root volume were observed in the treatment of 200 μM SA, 3% BC and Pb control. Also, the simultaneous application of SA and BC reduced Pb concentration in basil, so that the lowest one (0.67 mg/kg) was found in the treatment of 200 μM SA, 3% BC and Pb control. In contrast, the highest proline content (44.4 mmol/g) was obtained in 200 mg/kg of Pb and control of SA and BC. In general, the application of SA and BC could significantly reduce Pb-induced stress on growth characteristics in basil.

In order to investigate the effects of salicylic acid and superabsorbent polymer on yield and yield components in mung bean under different water regimes, a factorial experiment was conducted in complete randomized design with three replications in greenhouse of Razi University. Treatments included drought stress at three levels (30, 60 and 100% of FC), superabsorbent at three levels (0, 0.3 and 0.5% by weight) and salicylic acid at four levels (0, 250, 500 and 750 μM). The results showed that the highest grain yield (20.7 g per plant), biological yield (51.4 g/plant) and number of seeds per plant (79.1) were observed in 100% FC and application of 0.3% superabsorbent and 750 μM salicylic acid and the lowest values (0.13 and 7.5 g per plant and 16.2 seeds per plant, respectively) were obtained in 30% FC and no superabsorbent and salicylic acid treatments. In general, the concentration of 500 μM salicylic acid and 0.3% by weight of superabsorbent could neutralize the effects of severe drought stress.

Salicylic acid plays a vital role in increasing the resistance of plants to alkalinity stress. In this research, the interaction of alkalinity stress, salicylic acid and soil type on Mung bean growth parameters were investigated. This experiment was conducted as a factorial based on a complete randomized design with three replications in greenhouse of Razi University. Treatments included alkalinity stress (Sodium bicarbonate at three levels 0, 20 and 40 mM), salicylic acid at four levels (0, 250, 500 and 750 μM) and two soil types. The results showed that although alkalinity stress significantly reduced the growth parameters such as plant height, root/shoot ratio, number of active root nodes, leaf area and leaf relative water content and increased proline content of the plant at 1% level, but in contrast, salicylic acid spray mitigated them. Furthermore, there was a significant difference between the two soil types in terms of reducing the effects of stress. In general, the concentration of 500 mM salicylic acid, as an optimum concentration, could neutralize the effects of extreme tension in alkalinity.

The soil quality is defined as the ability of soil to function as an essential part of the human habitat. In this study, the effects of land use change (conversion of forest lands into agricultural lands) on the soil physical quality were studied in the Gilan-e-Gharb region. For this study, soil samples were collected from surface and subsurface layers of both land uses, and the peak and shoulder slope positions, in Miandar and Vidjanan catchments. Soil physical properties such as soil texture and particle size distribution, soil hydraulic conductivity, bulk density, mean weight diameter of aggregates, water holding capacity, and the soil organic carbon content were measured. The results showed that land use change of the forest to agricultural lands resulted in a sharp decline in the soil organic matter (52%) and an increase in silt and sand percentage and soil bulk density. Also, deforestation decreased the mean weight diameter of aggregates (from 0.39 to 0.14 mm in Miandar) and clay percent. It caused a reduction in the total porosity followed by a decrease of soil water holding capacity, and a decrease in the saturated hydraulic conductivity (from 10.34 to 1.86 cm/h), as well. In general, the results proved that the land use change from forest to agriculture severely decreased soil physical quality and its productivity.

Due to the effects of heavy metals on human health, removing them from the environment is essential. In this study, performance of several adsorbents in the removal of Pb from the soil solution was evaluated. A factorial experiment was conducted in a randomized design with three replications. Treatments included three types of adsorbents (zeolite, sunflower biochar and active carbon), four levels of Pb (0, 300, 600 and 900 mg/L of lead nitrate) and three different soil samples. According to the results, the best pH for absorbance of Pb was 5 and the proper balance time was 24 hours. Also, by increasing the adsorbent weight, the removal of Pb from the solution increased. In most cases Langmuir model described the data better than Freundlich. Since the total concentration of Pb desorption with zeolite and Biochar was less than active carbon, these adsorbents have higher efficiency than active carbon.

The present study was done to investigate a few decades application of raw municipal wastewater on soil physical quality and biological yield of wheat in Harsin. In this way, the main soil physical properties, which effect on soil physical quality, and total concentrations of some heavy metals in the soils of ten sites, that have been irrigated by wells water or wastewater, were statically analysed. The results showed that the use of wastewater, while added organic matter to the soil, improved aggregate stability, reduced soil bulk density, and increased other soil physical properties, including: saturated hydraulic conductivity, total porosity and saturation percentage. The total concentrations of Zn and Fe in the lands that had been irrigated by wastewater were significantly more than in the lands had been irrigated by wells water, while, concentrations of Cr, Pb and Ni were not significantly different. In general, application of wastewater improved the soil physical quality and meanwhile increased biological yield of wheat in the study area.

Soil hydraulic conductivity (K) is an important parameter in designing drainage systems and estimating water flow in soils, Although some methods are suggested for direct measurements of saturated hydraulic conductivity (Ks) but they are usually time consuming and costly. Pedotransfer functions (PTFs) is a valuable tool and indirect method to predict the Ks from the available soil data. The purpose of this research was to derive the best PTF that can predict saturated hydraulic conductivity values from the available parameters in Abadan. After basic studies drainage include logging (determination of texture, color, resistance to drilling, stickiness and plasticity) and determination of watertable, saturated hydraulic conductivity was measured on the soil columns using Ernest auger hole method then by exact semidetailed soil survey, morphological characteristics such as structure were specified as well, some physical and chemical properties of soil were measured, Geometric mean diameter (dg) and geometric standard deviation of soil particles (dg) were calculated by the exist equations. The multiple linear and nonlinear regression methods were used to develop the pedotransfer functions by using soil structure class, geometric mean diameter (dg), porosity and depth. From these four pedotransfer functions which were derived , the results indicated that accuracy of the derived PTF with R2=0.955 can predict the saturated hydraulic conductivity well from these four parameters and it can be used for primary estimation in order to design of irrigated poject.

Since gypsum affects on the soil physical¡ chemical and biological properties¡ so the presence of gypsum on soil behavior¡ including soil texture¡ is important. The aim of this study was to compare methods of soil texture determination; touching (field)¡ leaching¡ Hydromer and Hess¡ in the soils of Khoda afarin plain¡ Ardebil province¡ with an area about 21000 ha. For this purpose¡ soil samples collected from 20 soil profiles¡ with three replications and a factorial experiment was conducted in a completely randomized design. The results showed that although the two methods of soil texture determination (leaching and Hess) had similar soil texture classes¡ but in the touching method¡ because large crystals of gypsum (sand sizes)¡ soil texture may be estimated more coarse. Also¡ Hydromer method resulted an error in measuring of soil texture¡ because the flocculation of fine particles. In the measuring by pre-treatment of BaCl2¡ the success of accurate estimation of soil texture depends on gypsum percent and particle size distribution of gypsum crystals. In the gypsum complete leaching method¡ soil texture class was usually heavier than other methods¡ so that¡ the variance analysis table showed that the effects of leaching and particles BaCl2 coating¡ on the soil particles percentage has been significant at 1% level. So¡ removing of gypsum in the precise measurement of soil texture is not correct¡ because gypsum constitute a major component of the solid material and remove it from the gypsic soils does not have a scientific justification and basis.

Salinization and alkalization of soils are an agricultural problems in arid and semiarid regions of the world such as Iran. In this experiment the effects of salicylic acid (SA) on resistance of pepper under salt and alkali stresses was investigated. Experimental treatments include 0 and 150 mM of NaCl stress, 0, 50 and 100 mM of Na2Co3/NaHCo3 and 0. 0.75 and 1.5 mM SA. Results showed that salt and alkali stresses imposed negative effects on plant growth and productivity. Reduction in growth and yield in salinity condition was higher than alkaline condition and maximum reduction occurred in mixed stresses. Application of SA in both conditions significantly increased yield, plant growth parameters and chlorophyll content. For most traits, 0.75 mM of SA was more effective than 1.5mM concentration. In general, Salinity and alkalinity have negative effects on growth and yield of pepper plant and these negative effects can be reduced by application of SA.

In this study, the effect of 5-Aminolevolinic acid (ALA), a key precursor in the biosynthesis of porphyrin and the new plant growth regulator, was studied on some physiological responses of coriander plant under drought stress. The layout was a factorial experiment in randomized complete block design (RCBD) with three levels of drought stress (irrigation within 100%, 60% and 30% field capacity) and four concentrations of ALA (0, 0.25, 0.5 and 1mM) as factors. The experiment was conducted in the greenhouse of agricultural faculty of Ilam University in 2010. Statistical analysis showed the significant effects of the drought and ALA on plant physiological parameters including leaf relative water content (RWC), water use efficiency (WUE), praline, malondialdehyde (MDA) and chlorophyll content. In drought conditions, chlorophyll content and RWC were reduced but MDA accumulation, praline content and WUE increased. ALA application significantly caused increasing of RWC, WUE, chlorophyll content and proline accumulation and decreasing of MDA content in plant. In this study, ALA treatment with increasing of praline and chlorophyll content and reducing of MDA accumulation decreased the adverse effects of drought stress on the coriander plant.

Drought stress is a major constraint for crop production in arid and semiarid regions, such as Iran. In this study the effect of 5-aminolevolinic acid (ALA), the new plant growth regulator, on Coriander (Corianderum sativum L.) plants under drought stress was studied. The layout was factorial experiment in randomized complete block design (RCBD) with 3 levels of drought stress including stress-free conditions (irrigation within the field capacity), mild stress (humidity of soil about 60% of field capacity) and severe stress (humidity of soil about 30% of field capacity) and 4 concentrations of ALA (including 0 (as a control), 0.25, 0.5 and 1 mM) as main factors and 4 replication. The experiment was conducted in the greenhouse of agricultural faculty of Ilam University. Statistical analysis showed significant effects of the drought and ALA on plant growth parameters, chlorophyll index and antioxidant activity. Result showed that drought stress imposed negative effects on plant growth and productivity. In drought conditions, plant height, leaf area, plant and leaf dry and fresh weight and chlorophyll index reduced but antioxidant activity increased. ALA application significantly caused increasing of plant height, leaf area, plant and leaf dry and fresh weight, chlorophyll index and antioxidant activity. ALA treatment with increasing of chlorophyll and antioxidant activity decreased adverse effects of drought stress on coriander plants. These results suggest that ALA has plant growth regulating properties at low concentrations and may enhance agriculture productivity under drought condition.