The role of microbial activity on iron uptake of wheat genotypes different in fe-efficiency

Soils in many agricultural areas have high pH, resulting in low availability of Fe. Wheat grown on such soils suffers from most micronutrient deficiencies, in particular Fe deficiency. The objective of this investigation was to determine the potentials of indigenous fluorescent Pseudomondas for siderophore production and their effects on 59Fe acquisition. For this purpose, some strains of Pseudomonas putida, Pseudomonas fluorescens, and Pseudomonas aeruginosa were isolated from different locations representing rhizosphere of wheat. The potentials of these strains for siderophore production were evaluated by chrome azorel-S assay (CAS blue agar) through color change. High siderophore producing Super-strains were selected for extraction of siderophores. These isolates were grown in SSM (standard succinate medium) for 72 hr at 28 C. Bacterial cell were removed by centrifugation (10000 g for 20 min) and the supernatant was filtered through filter membrane (0.22 ) and used as crowd siderophore. Evaluation of Fe uptake and translocation were carried out with complexes of bacterial siderophores and 59Fe compared with standard sierophore Desferrioxamine (DFOB) in randomized complete block design with three replications. This experiment was conducted on two wheat genotypes different in Fe-efficiency at hydroponic condition. The results showed that among the three most effective siderophores producing strains considered, the P. putida produced a sidrophore complex that showed efficiencies of 76 %, compared with the standard siderophore (DFOB) in the uptake of Fe and was statistically in the same group as the control. The effect of bacterial siderophores in the uptake of labeled 59Fe by wheat became significant, indicating that the chemical structure of the siderophores from different strains were different. The effects of wheat genotype in 59Fe activity of shoots was also significant, where the efficient Tabasi genotype contained 46 % more Fe in shoots than the inefficient Yavarous genotype. It was concluded that the siderophore complex from P. putida was the most effective in translocating Fe to shoots, particularly in efficient Tabasi genotype. Siderophore effectiveness in Fe availability decreased in the order; Sid-DFOB> Sid-putida>Sid-fluorescens> Sid-areuginosa

The effect of PGPR inoculation on the growth of wheat

Many agricultural soils of Iran have high pH, resulting in low availability of Fe and Zn. The potentials of nonsymbiotic plant growth-promoting rhizbacteria (PGPR) for stimulating plant growth have been extensively used during recent decades. This experiment was carried out in growth chamber to evaluate the effects of siderophoreproducing Pseudomonads on the growth as well as Fe and Zn uptake of wheat. A randomized complete block design experiments was conducted using with Alborz genotype (an efficient phytosiderophore-producing bread wheat) treated with either 7NSK2 strain as a siderophore positive (sid+) or with MPFM1 mutant strain of the same isolate as a siderophore negative (sid-) treatments with three replications. The potentials of these strains for auxin production and phosphate solubilizing activity were evaluated by standard methods. The results showed that inoculation with sid+ strain increased dry matter production in shoots as compared with the control (sterile condition) or with sid - strain. Likewise, the concentration of chlorophyll a in leaves of sid+ and sid - treatments were 1.27 and 0.41 g mg-1 of fresh weight, respectively, and the concentration of chlorophyll b were measured to be 1.09 and 0.35 g mg-1 of fresh weight, respectively, indicating significantly more chlorophyll formation due to inoculation with sid+ as compared with sid -. The uptake of Fe by roots and its rate of translocation to the shoots were greater for the sid+ treated plants as compared with the sid - treated ones, indicating that siderophores increased the rate of Fe uptake by wheat. The effect of microbial inoculation on shoot Zn was not significant, but increased the concentration of Zn on roots compared with control. The results suggested that the siderophores of Pseudomonads may involve on increasing bioavailability of iron

Potential of indigenous microbes as helping agents for phyto-restoration of a Pb-contaminated soil

The aim of this study was to assess the effects of heavy metal tolerant soil microbes inoculation on growth and metal uptake of pearl millet, Pennisetum glaucum, couch grass,Triticum repens and alfalfa,Medicago sativa in a soil spiked (and subsequently aged) with increasing concentrations of Pb. A soil sample (soil 1) was spiked with increasing (0 to 1500 mg/kg) concentrations of Pb and incubated for a seven months period. Another soil sample with a historical background of metal contamination (soil 2), having heavy metals-resistant microbial communities, also was taken and used as inocula. The plants were grown in pots containing contaminated soils. At the end of growth period, plants shoots were harvested, washed, oven-dried, ground and analyzed for Pb. The results showed a significant reduction (p < 0.05) in plants yield by increasing soil Pb concentration and inoculation of stress-adapted microbes further increased this reduction. This could be attributed to the increased access of plants to the relatively immobile Pb existed in the studied calcareous soil as well as to more metal contaminant absorption caused by soil microbial activity. In general, introduction of the microbes also resulted in lower Pb uptake by the studied plants

The Role of Mycorrhizal Inoculation on Growth and Essential Oil of Peppermint (Mentha piperita)

Introduction: Arbuscular mycorrhizal symbiosis is formed by approximately 80% of the vascular plant species in all terrestrial biomes. Using soil microbial potential including arbuscular mycorrhizal fungi (AMF) has been widely considered for improving plant growth, yield and nutrition. Medicinal herbs are known as sources of phyto chemicals or active compounds that are widely sought worldwide for their natural properties. Members of the Lamiaceae family have been used since ancient times as sources of spices and flavorings and for their pharmaceutical properties. Peppermint (Mentha piperita) has a long tradition of medicinal use, with archaeological evidence placing its use at least as far back as ten thousand years ago. Essential oils - are volatile, lipophilic mixtures of secondary plant compounds, mostly consisting of monoterpenes, sesquiterpenes and phenylproponoids.Arbuscularmycorrhizal fungi with colonizing plant roots improve nutrient uptake as well as improving essential oil yield of medicinal plants by increasing plant biomass. The aim of the present study was to evaluate the effect of AMF inoculation on essential oil content and some growth parameters of peppermint (Mentha piperita) plant under glasshouse condition. Materials and Methods: This study was performed on a loamy sand soil. The samples were air-dried, sieved