فهرست مطالب vahid alah jahandideh mahjen abadi

Soil salinity and sodicity disrupt the balance of nutrients in the soil and create restrictions on plant growth. An experiment was conducted to evaluate the application of sulfur along with Thiobacillus bacteria and plant growth-promoting bacteria isolated from saline-sodic soils on the performance and concentration of micronutrients in wheat (Chamran cultivar) in saline-sodic soils in a factorial design within a completely randomized design, in three replications in greenhouse condition. The experimental factors included three types of saline-sodic soil (S1: SAR=13 and EC=8 dS m^-1), (S2: SAR=15 and EC=10 dS m^-1), and (S3: SAR=17 and EC=14 dS m^-1), four levels of plant growth-promoting bacteria (B0: control, Pseudomonas alcaliphila, Rhizobium pusense, and Bacillus subtilis) and two levels of sulfur along with Thiobacillus thiooxidans bacteria (T0: no application and T1: application of 31.4 grams per pot (10 tons per hectare) of powdered sulfur along with T. thiooxidans bacteria). Based on the sequencing of the 16S rRNA gene, the superior plant growth-promoting bacteria were identified as Pseudomonas alcaliphila, Bacillus subtilis, and Rhizobium pusense. The results showed that adding sulfur along with T. thiooxidans bacteria and other plant growth-promoting bacteria at different levels of salinity and sodicity led to an increase in grain yield and concentration of micronutrients compared to the control. At the salinity and sodicity levels of S1 and S3, the highest grain yield was observed in plants inoculated with R. pusense bacteria (13.1% and 88.8%, respectively). The combination of plant growth-promoting bacteria and sulfur along with T. thiooxidans bacteria did not have a significant effect on grain yield and concentration of micronutrients in saline-sodic soils. Overall, the individual application of R. pusense bacteria isolated from saline-sodic soils and sulfur along with T. thiooxidans bacteria plays a significant role in improving the performance and concentration of micronutrients in wheat in saline-sodic soils.

Information on soil pollution assessment and suitable extractants to determine the available amounts of heavy metals in calcareous and saline soils of Iran are limited. Therefore, this study aimed to compare EDTA pH 4.65, EDTA pH 8.6 and, DTPA pH 7.3 extractants to characterize availability of heavy metals including copper, cadmium, lead, and nickel in calcareous and saline soils of Khuzestan Province. To this end, 63 soil samples were collected from wheat fields of the province and wheat was planted under greenhouse conditions using randomized complete design with three replications. Due to salinity limitation, sequential leaching by two pore volumes of each soil was applied. Plant available amounts of copper, cadmium, lead and nickel in soils were measured with the extractants before and after leaching. Result demonstrated that DTPA pH 7.3 and EDTA pH 4.65 extracted the lowest and the highest amounts of heavy metals, respectively. Salinity reduction had different impacts on the heavy metals extraction based on the type of the metal and extractants, such that uniform and similar trends were not observed for the extracted metals. There was a significant positive correlation between the extracted copper of all three extractants and wheat copper content. This correlation for DTPA pH 7.3 extractant (r = 0.32, P ≤ 0.01) was higher than EDTA pH 4.65 (r = 0.27, P ≤ 0.05) and EDTA pH 8.6 (r = 0.25, P ≤ 0.05) extractants. For cadmium and lead, only positive and significant correlations (r = 0.33, P ≤ 0.01 and r = 0.28, P ≤ 0.05, respectively) were obtained between DTPA extract and their concentrations in wheat. No significant correlation was recorded between wheat nickel content with any of the extractants. Based on the results, it seems that the DTPA may be introduced as the most suitable extractant to determine the available copper of wheat in the calcareous and saline soils of Khuzestan. However, by considering the soil salinity, leaching requirement, and the weak correlations between the studied extractants and the plant available soil cadmium, lead, and nickel, further studies are recommended for assessment of these heavy metals.

The plant growth promoting bacteria (PGPB) inhabiting the phyllosphere of different plants provides a tool for more efficient use of bacteria as a source of biofertilizers. The use of molecular technologies leads to in-depth research of the phyllosphere microorganisms and may provide new avenues for the development and validation of modern agricultural operations and significantly increase productivity. The aim of this research was to investigate the plant growth promoting (PGP) traits of bacteria isolated from maize (Zea mays L.) phyllosphere cultivated in different geographical zones of country (Iran) and their molecular identification by 16Sr RNA sequencing.

In September (2016), 116 samples of healthy mature leaves were collected from the maize fields located in 6 provinces of Iran (Fars, Alborz, Qazvin, Khuzestan, Tehran and Khorasan) and then, phyllosphere bacteria were isolated from them. Growth promoting traits of bacteria including Indole-3 Acetic acid (IAA) production, organic phosphate dissolution, siderophore production, exopolysaccharides (EPS) production and also nitrogenase enzyme activity were measured using standard methods. Superior strains were identified based on 16S rRNA sequencing method.

The 10 from 242 bacterial strains isolated from maize phyllosphere were selected based on their growth promoting traits. All strains selected demonstrated nitrogenase activity, organic phosphate dissolution and IAA and EPS production capability. The highest nitrogenase activity (70.31 nM ml-1 h-1) and organic phosphate dissolution (75.05 g l-1) were observed in THE15 strain, while the lowest amount of these properties belonged to KHO57 (5.55 nM ml-1 h-1) and KHO51 (15.90 g l-1) strains, respectively. The QAZ26 and TEH15 strains had the highest amount of IAA production (31.56 and 30.00 µg ml-1, respectively) and the ALB32 strain produced the lowest amount of IAA (4.50 µg ml-1). The EPS production by strains ranged from 0.120 to 1.805 g l-1. Among the strains investigated, only KUU32, KHU53, ALB32 and QAZ26 were able to produce siderophore. 16S rRNA sequencing revealed that the 10 strains selected belong to Bacillus, Microbacterium, Pseudarthrobacter, Pseudomonas, Stenotrophomonas, Enterobacter and Kocuria genera. The Bacillus with 4 different species (including Bacillus subtilis, Bacillus megaterium, Bacillus paralicheniformis and Bacillus pumilus) was the most dominant genus.

Based on the results of this study, Bacillus was the most dominant genus of plant growth promoting bacteria in the maize phyllosphere. Among the isolated bacteria, Enterobacter hormaechei TEH15 was highly capable of nitrogenase enzyme activity, IAA and organic phosphate solubility. Therefore, this strain deserves further research in greenhouse and field studies of maize cultivation and maize family plants.

Using different organic beds to produce vermicompost may influence on quality of vermicompost and its derived productions.
A greenhouse experiment was conducted to compare the properties of vermicompost, vermiwash and vermicompost tea obtained from three types of organic beds consisted of cow manure, leaf meal and a combination of cow manure and leaf meal (1:1 w/w).
Cow manure vermicompost had more desirable effect on many measured traits toward leaf meal and combination of leaf meal and cow manure vermicomposts. Vermicompost tea obtained from three vermicompost types was richer in terms of macro and micro nutrients, C/N, percent of organic matter and organic carbon toward the vermiwash produced from the same vermicompost. Vermiwash and vermicompost tea produced from cow manure vermicompost were at first order in majority of measured traits toward others.
Generally vermicompost which was richer in nutrient concentrations affected intensively quality of vermiwash and vermicompost tea produced from it.

This research investigate the potential of Rhizobium leguminosarum b.v. phaseoli to improve growth and nutritional status of common bean (Akhtar cultivar) at three levels of salinity of S0, S1 and S2 (0, 35 and 70 mM sodium chloride, or 0, 3 and 6 ds/m, respectively). The greenhouse experiment was conducted as a factorial design in randomized completely with three replications by using the sterile sand-perlite (2:1 v/v) as a culture substrate. The results showed that salinity decreased plant growth, regardless of microbial treatment and stress level. The inoculated plants with rhizobium had greater shoot and root biomass than the non-inoculated plants at all salinity levels. Salinity stress decreased enzyme activity catalase and potassium and nitrogen concentrations of shoot and increased enzyme activity peroxidase sodium concentration of shoot, particularly in non-inoculated plants with rhizobium. At salinity levels of S1 and S2, enzyme activity catalase of inoculated plants with rhizobium about 196% and 259% and enzyme activity peroxidase about 93%, 73% and 7% was increased than the non-inoculated plants, respectively. Inoculation of rhizobium at salinity levels of S1 and S2, resulted in increasing of potassium concentration about 84% and 10% and decreasing of sodium concentration about 50% and 70%, respectively. Also, the inoculated plants with rhizobium had higher nitrogen concentrations at S0 and S2 in compare to the non-inoculated. Shoot phosphorous concentration of inoculated plants with rhizobium was higher about 55% than the non-inoculated plants.

Biological methods based on using soil beneficial microorganisms’ potentials for creating symbiosis relationship with plants by modifying genetic structure of plants resulting in improving nutritional status and crops quality. This study was conducted in order to investigate the effect of Piriformospora indica inoculation on root colonization and uptake and transportation of phosphorus, zinc and iron by two wheat cultivars (Nicknejad and Azadi) in sterile sand-perlite (2:1 v/v) pot medium. The greenhouse experiment was conducted as a factorial, completely randomized design with three replications. Inoculation of P. indica increased chlorophyll a, b and total chlorophyll concentrations of Nicknejad cultivar, however had no significant effect on the mentioned index in Azadi cultivar. P. indica inoculation resulted in increase and decrease of iron concentration in shoot and root parts of Nicknejad cultivar, respectively. Despite of no significant effect of P. indica on root zinc concentration of Nicknejad cultivar, this fungus played an important role in increasing zinc concentration in the shoot of this cultivar. P. indica resulted in increase of zinc concentration in the root of Azadi cultivar but, had no significant effect on shoot zinc concentration. Phosphorus concentration in shoot and root of Nicknejad cultivar inoculated with P. indica, increased. Inoculation of P. indica resulted in increase of phosphorus concentration in shoot of Azadi cultivar but, had no significant effect on phosphorus concentration of root. In general, Nicknejad cultivar is proposed as a high compatible cultivar with the P. indica in order to enhancing nutrient uptake and thus improving yield quality.