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The effect of different fungicides on mycorrhizal fungi should be investigated in different plants and environmental conditions. Thus, the purpose of this study was to appraise the effect of simultaneous fungicides application (including benomyl, rovral TS, mancozeb, and tilt) on the efficiency of Rhizophagus irregularis in cultivations of maize and wheat. This study was conducted in two separate experiments in the laboratory and greenhouse. The results of the laboratory stage showed that the use of all four fungicides significantly reduced the spore number compared to the conditions of non-use of the fungicide, although only rovral TS and mancozeb led to a significant reduction in root colonization percentage of R. irregularis. In the greenhouse, the benomyl significantly increased root dry weight in maize although tilt significantly reduced root colonization of maize with R. irregularis. The tilt and rovral TS had a positive effect and benomyl had a negative effect on wheat growth traits, but the root colonization of wheat with R. irregularis was not affected by fungicides. Generally, benomyl (2 g L-1) in maize and tilt (2 mL L-1) in wheat and rovral TS in both plants could be recommended with the combined application of R. irregularis inoculants. Therefore, depending on the type of fungicide and the host plant, the effect of the fungicide on colonization and association of mycorrhiza varies.

Earthworms are the most important soil invertebrates worldwide, in terms of biomass and effects on soil processes. In this study, 21 earthworm species, including four new records were identified from Caspian Hyrcanian Forests (North of Iran). Four species; Criodrilus lacuum, Lumbricus rubellus, Metaphire californica, and Octodrilus transpadanus and the family Criodrilidae are reported for the first time. Previous studies have identified 31 earthworm species belonging to 14 genera and three families (Lumbricidae, Acanthodrilidae, and Megascolecidae) in Iran; therefore, these new records increase the number of earthworm species to a total of 35.

One appropriate strategy for refining heavy metals could be based on bioprecipitation by ureolytic bacteria. The study was conducted to isolate urease-producing bacteria from the contaminated soils and evaluate the potential of selected isolates in biomineralization of heavy metals.To this end, four isolates which had the greatest urease production, calcite precipitation, and endurance to the heavy metals were obtained from contaminated areas during the screening steps. These isolates along with Sporosarcina pasteurii were used to bioprecipitate zinc (Zn), lead (Pb), and cadmium (Cd) from solutions with concentrations of 100, 300, and 500 mM of these metals’ ions. Amount of heavy metal precipitates formed by these bacteria were compared.Among these isolates, Stenotrophomonas rhizophila (A323) and Variovorax boronicumulans (C113) produced the highest carbonate minerals of heavy metals. S. rhizophila removed 96.25%, 71.3 %, and 63.91% of Pb, Cd, and Zn, respectively, after 72 h of incubation. Also, V. boronicumulans removed 95.93% of Pb, 73.45% of Cd, and 73.81% of Zn after having the same amount of time for incubation. S. pasteurii eliminated 98.71% of Pb, 97.15% of Cd, and 94.83% of Zn. The presence of lead, zinc, cadmium, and carbon as well as oxygen in precipitates formed from biomineralization of heavy metals was confirmed by energy dispersive spectroscopy (EDS). The S. pasteurii produced higher amounts of metal carbonates. Nevertheless, the use of selected bacteria in bioremediation of contaminated sites may be more effective due to the stability of these bacteria in high concentrations of Pb, Zn, and Cd.

Drought stress is one of the main constraints limiting worldwide crop production. Arbuscular mycorrhizae (AM) and plant growth-promoting bacteria (PGPB) such as Azotobacter chroococcum and Azospirillium lipofrum have been shown to alleviate drought stress effects. Therefore, the interaction effect of AM fungi [Glomus mosseae, G. etunicatum, and a mix of these (G. mix), and PGPB bacteria (Azotobacter chroococcum + Azospirillium lipofrum)] was investigated in 1-year-old walnut seedlings (cv. Chandler) under normal and drought stress conditions. Drought stress reduced growth (plant height, root length, number of leaves, and fresh weight) and leaf nutrient content (N, P, and Zn) significantly of walnut plants. In contrast, proline, total soluble sugar, starch peroxidase enzyme activity, and total phenolic content of walnut leaves increased under this stress. Application of fungi or bacteria, and especially their simultaneous use, alleviated the negative effects of drought stress on walnut seedlings. AM fungi and PGPB increased significantly the content of some metabolites, including total phenolic content, proline level, peroxidase activity, total soluble sugar, and starch content as well as peroxidase enzyme activity. This led to an increase in walnut plant growth under the drought stress condition. Among AM fungi, G. etunicatum was more effective in reducing drought stress symptoms than either G. mosseae or the G. mix of fungi. In conclusion, use of G. etunicatum, along with PGPB, can reduce negative effects of drought stress on walnut seedlings.

Using of arbuscular mycorrhizal fungi (AMF) has emerged as a new technique to alleviate the toxic metals stress through changing their chemical behavior. The present work was conducted as a factorial arrangement based on a completely randomized design to study the inoculation effects of Glomus intraradices, Glomus mosseae and Glomus etunicatum, on Pb and Zn fractions in the rhizosphere of alfalfa by using rhizobox technique in two agricultural soils with different Zn and Pb concentrations [with low (LH) and high (HH) concentration levels]. The results showed that AMF colonization promoted plant growth and lowered the shoot and root Pb and shoot Zn concentrations in the studied soils compared to uninoculated treatments. Mycorrhizal colonization significantly increased the Ca(NO3)2- extractable Zn and ORG-Zn (respectively 500 and 59.6% more than the uninoculated treatment) and decreased the OXI-Zn (20.32% less than the none inoculated treatment) in the HH soil. By contrast, mycorrhizae slightly increased the CARB, OXI and ORG-Zn forms in the LH soil compared to the uninoculation condition. In the AMF- treated HH soil, an increase was recorded in the Ca(NO3)2- extractable Pb, EXCH-Pb and CARB-Pb (respectively, 17.65, 3.09 and 14.22% compared to the none inoculated treatment) and a decrease in the OXI and ORG-Pb forms (respectively, 28.79 and 13.51% compared to the uninoculated treatment). A reverse status was observed for Pb changes in the LH soil. Depending on the contamination level, the mycorrhizal inoculation differentially affected the Pb and Zn fractions at different distances from the root surface. In the LH soil, at 5 mm distance) while ORG-Zn was increased up to 48.63%. However, Ca(NO3)2- extractable, CARB and ORG-Pb was increased in rhizosphere soil (respectively, 89.33, 3.84 and 6.14%) and OXI-Pb was decreased up to 10.36% compared to the bulk soil. In the HH soil, mycorrhizal inoculation increased the CARB and OXI-Zn (respectively, 1.76 and 5.71%) and OXI-Pb fractions (11.56%) compared to the

More details have yet to be indicated on the interactions between arbuscular mycorrhizal (AM) fungi and phosphorus (P) chemical fertilization under field conditions. Accordingly, the objectives were to: (1) evaluate the combined effects of mycorrhizal fungi and chemical P fertilization on maize yield, yield components, and nutrient uptake and (2) indicate the optimum rate of P chemical fertilization (P1, P2, P3) with the use of mycorrhizal fungi (Glomus intraradices and G. mosseae). A factorial experiment using randomized complete blocks with three replicates, conducted at the Research Station of the Faculty of Agriculture, Islamic Azad University, Tabriz branch, Iran. Results indicated the significant effect of P, AM fungi, and their interaction on most of the measured traits. Grain yield (7909.3 kg/ha), maize nutrient content of P (0.39%), zinc (Zn) (42.1 mg/kg), iron (Fe) (68.3 mg/kg), and the colonization rate (47.5%) were all the highest by the interaction of G intraradices × P2.

Soil salinity and arbuscular mycorrhizal fungi (AMF) influence the soil hydrophobicity. An experiment was performed to determine the effects of soil salinity and AMF species on soil water repellency (SWR) under wheat (Triticum aestivum L.) crop. Six AMF treatments, including four exotic species (Rhizophagus irregularis, Funneliformis mosseae and Claroideoglomus claroideum, a mix of three species), one mix native AMF species treatment and an AMF-free soil in combination with four salinity levels (1, 5, 10, and 15 dS m−1) were used. The soil repellency index (RI) increased with salinity increment ranging from 2.4 to 10.5. The mix of three exotic and native AMF treatments enhanced the RI significantly compared to AMF-free soil in all salinity levels with one exception for native treatment at 1 dS m−1. Among individual AMF species, the C. claroideum treatment at 10 dS m−1 increased the RI by 67% compared to AMF-free soil. The native AMF treatment was more efficient in root colonization, glomalin production an...

The hypothesis was that arbuscular mycorrhizal (AM) fungi are able to alleviate salt stress on plant growth by enhancing and adjusting mineral uptake. The objectives were to determine (1) the effects of soil salinity on mineral uptake by different wheat genotypes and (2) the effectiveness of different mycorrhizal treatments on the mineral uptake of different wheat (Triticum aestivum L.) genotypes under salinity. Wheat seeds of Chamran and Line 9 genotypes were inoculated with different species of AM fungi including Glomus mosseae, G. intraradices, and G. etunicatum and their mixture at planting using 100 g inoculum. Pots were treated with the salinity levels of 4, 8, and 12 dS/m before stemming. Different arbuscular mycorrhizal treatments, especially the mixture treatment, increased wheat mineral uptake for both genotypes. Although Line 9 genotype resulted in greater nutrient uptake under salinity stress, Chamran was more effective on adjusting sodium (Na+) and chloride (Cl−) uptake under salt stress.

In recent years, applying humic acid (HA) has been common in turfgrass management. A series of experiments were conducted to evaluate the effect of HA on qualitative and quantitative characteristics of “Speedygreen” perennial ryegrass (Lolium perenne L.). Different concentrations of HA (0, 100, 400, and 1000 mg L−1) were applied monthly as foliar application. Results showed that leaf phosphorus (P), potassium (K), and zinc (Zn) content, fresh and dry weight, chlorophyll content, and root fresh weights were not affected by HA. Meanwhile, HA improved the root and shoot development, except for root fresh weight. While just 100 mg L−1 improved height, visual quality, nitrogen (N) content, roots length, and surface of roots, all of HA concentrations were effective on iron content. These results suggest that HA foliar application might be of benefit to enhance some nutrients uptake and root development of ryegrass possibly leading to improved drought resistance.

It has been previously indicated that arbuscular mycorrhizal (AM) fungi can enhance the bioremediation abilities of their host plant. Barley (Hordeum vulgare L.) is a crop plant with some unique physiological properties, such as tolerance to salinity. However, its tolerance to other stresses such as heavy metals must be tested. Accordingly, it was hypothesized that barley can be efficiently used to treat heavy metals in symbiotic and non-symbiotic association with AM fungi. In a greenhouse experiment barley plants were inoculated with the AM species Glomus mosseae and grown in a soil polluted with cadmium (Cd), cobalt (Co), and lead (Pb). Relative to Cd and Co, mycorrhizal barley absorbed significantly higher amounts of Pb. AM species also significantly decreased Cd and Co uptake by barley indicating the alleviating effects of G. mosseae on the stress of such heavy metals.

1. Marco N. Barusco, MD (drbarusco{at}tempushair.com) 1. Port Orange, Florida, USA 2. Farhad Rejali, MD (bamehr2000{at}yahoo.com) 1. Esfahan, Iran ![Figure][1] In this submission, Dr. Farhad Rejali describes an interesting case of alopecia totalis that occurred after 2 sessions

Phosphorus (P) behavior and its efficiency in mycorrhizal plants are of great importance. The objective was to evaluate the behavior of soil labeled P absorbed by different mycorrhizal wheat genotypes subjected to saline water. Three wheat genotypes including cultivar Kavir, the local cultivar Roshan, and the mutated line Tabasi T-65-7-1 were inoculated with different species of arbuscular mycorrhiza (AM) including Glomus etunicatum, G. mosseae, and G. intraradices. Plants were irrigated using saline water (electrical conductivity of 13.87 dS m−1). The experiment was a factorial with 12 treatments and three replications under greenhouse conditions. Wheat genotypes and AM species significantly affected plant dry weight, specific activity, and total plant activity (P = 0.01). A maximum of 1.49-fold increase in specific activity or P uptake per gram of plant dry matter and 3.53-fold increase in plant activity or plant total P uptake resulted by G. etunicatum as compared with control.

Three pot experiments were set up to determine how efficiently mycorrhizal fungi affect the uptake, translocation, and distribution of labeled phosphorus (32P), phosphorus (P), and heavy metals in alfalfa (Medicago sativa L.). In experiments 1 and 2, the efficiencies of different arbuscular mycorrhizal fungi (AMF) species including Glomus mosseae, G. etunicatum, G. intraradices and a mixed strain (G. mosseae, Gigaspora hartiga, and G. fasciculatum) on uptake, translocation, and distribution of 32P and P in alfalfa were investigated, respectively. In a third experiment, the efficiency of G. mosseae on uptake and distribution of heavy metals [cadmium (Cd), cobalt (Co), lead (Pb), and combinations] was tested. Results of experiments 1 and 2 suggest that G. mosseae was the most effective at increasing the uptake of 32P and P. Experiment 3 result showed that in the triple-metal-contaminated soil, inoculated plants had greater Co (32.56 mg kg−1) and Pb (289.50 mg kg−1) concentration and G. mosseae enhanced the ...

Drought stress is an abiotic stress that imposes serious constraints on plants. The present investigation was carried out to determine the inter-relationship between some physiological attributes of soybeans affected by drought stress and pure isolates of Azotobacter and Azospirillum. Drought stress and bacterial application increased catalase and glutathione peroxidase activity, whereas drought stress increased superoxide dismutase activity during the pod-filling stage. Abscisic acid and proline levels increased due to drought stress and bacterial application during the flowering stage, whereas total plant nitrogen was enhanced under well-watered conditions when plants were inoculated with bacteria. The close relationship between enzyme activity and drought stress with bacteria indicated that antioxidant enzymes play an important role in alleviating the detrimental effects of water stress. In addition, the enhancement of abscisic acid and proline could be positively linked with drought stress, and drought-induced abscisic acid could induce proline accumulation and the expression of antioxidant enzyme genes.

The ability of Rhizobia to colonize roots of certain legumes and promote their growth has been proven previously. In this study the symbiotic efficiency of 47 Rhizobium strains with 6 common bean cultivars was evaluated under greenhouse condition. Fourteen strains showed the best symbiotic efficiency, whereas some isolates could not induce nodules on host plants. The ability of fourteen superior strains to solubilize phosphorus and zinc and to produce auxin, HCN and siderohores was evaluated in the laboratory assays. Rhizobium strain Rb102 produced the highest amount of auxin (14.2 mg l−1) in the medium containing l-tryptophan. None of the isolates were able to solubilize ZnO and ZnCO3 on solid medium but in liquid medium some of them had negligible solubilization. The highest P solubility in liquid and solid medium was observed in strains Rb113 and Rb130, respectively. Strain Rb102 produced the highest amount of siderophores. None of the isolates were able to produce HCN. This study showed that there was a great diversity between the strains of Rhizobium in terms of their plant growth promoting traits symbiotic efficiency which supports the importance of screening rhizobia for selecting the most efficient strains. The genetic diversity of the isolates was analyzed by PCR–RFLP of the 16S rDNA. Our rhizobia were clustered into 10 groups showing high levels of diversity.

Salinity toxicity is a worldwide agricultural and eco-environmental problem. The intent of this study was to determine the salt tolerance of Piriformospora indica and strains of Azospirillum, isolated from non-saline and saline soil, as well as to determine their affect on the tolerance of wheat to soil salinity. In this study, an experiment was conducted to investigate the salt stress tolerance abilities of the endophytic fungi, P. indica, and Azospirillum strains, isolated from non-saline and saline soil, at five NaCl levels (0, 0.1, 0.2, 0.3, 0.4, 0.5 mol L−1). Additionally, a greenhouse experiment was conducted to test the effects of these selected microorganisms under increasing salinity levels on seedling growth, solute accumulation (proline and sugars), and photosynthetic pigments (Chl a, b, ab) of seedling wheat. Azospirillum strains were isolated in Iran from the root of field-grown maize from non-saline soil with an EC = 0.7 dS m−1 and from saline soil with an EC = 4.7 dS m−1. Plants were irrigated with non-saline water–tap water with an electrical conductivity water (ECw) value of 0.2 dS m−1, as well as low, moderate and severe saline water-irrigation with saline water with an ECw of 4 dS m−1, 8 dS m−1 and 12 dS m−1, respectively. The upper threshold of P. indica salinity tolerance was 0.4 mol L−1 NaCl in both liquid and solid broth medium. The upper thresholds of the salt adapted and non-adapted Azospirillum strains were 0.2 and 0.4 mol L−1 NaCl, respectively. The results indicated a positive influence of the organisms on salinity tolerance, more with the saline-adapted Azospirillum strains than the non-adapted strains. P. indica was more effective than the Azospirillum strains. These results could be related to a better water status, higher photosynthetic pigment contents and proline accumulation in wheat seedlings inoculated with P. indica. The benefits of both isolates and P. indica depended on two factors: water salinity and growth stage of the host plant. Inoculation with the two isolates increased salinity tolerance of wheat plants; the saline-adapted Azospirillum strains showed better performance with respect to improved fresh and dry weights at 80 and 100 days after sowing under both non-saline and saline conditions. When compared to plants inoculated with non-saline-adapted Azospirillum strains, those inoculated with adapted Azospirillum strains had much better performance with respect to the presence of photosynthetic pigment (Chl a, b and ab) and proline accumulation. Overall, these results indicate that the symbiotic association between P. indica fungus and wheat plants improved wheat growth, regardless of the salinity. It is concluded that the mechanisms for protecting plants from the detrimental effects of salinity by P. indica fungus and Azospirillum strains may differ in their salinity tolerance and influence the uptake of water, photosynthetic pigment contents and proline accumulation in wheat seedlings.

Since most experiments regarding the symbiosis between arbuscular mycorrhizal (AM) fungi and their host plants under salinity stress have been performed only under greenhouse conditions, this research work was also conducted under field conditions. The effects of three AM species including Glomus mosseae , G. etunicatum and G. intraradices on the nutrient uptake of different wheat cultivars (including Roshan, Kavir and Tabasi) under field and greenhouse (including Chamran and Line 9) conditions were determined. At field harvest, the concentrations of N, Ca, Mg, Fe, Cu, and Mn, and at greenhouse harvest, plant growth, root colonization and concentrations of different nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl were determined. The effects of wheat cultivars on the concentrations of N, Ca, and Mn, and of all nutrients were significant at field and greenhouse conditions, respectively. In both experiments, AM fungi significantly enhanced the concentrations of all nutrients including N, K, P, Ca, Mg, Mn, Cu, Fe, Zn, Na and Cl. The synergistic and enhancing effects of co-inoculation of AM species on plant growth and the inhibiting effect of AM species on Na + rather than on Cl − uptake under salinity are also among the important findings of this research work.

A greenhouse experiment was conducted in order to evaluate the interactive effects of microbial inoculants on uptake of nutrient elements (N, P, K, Ca, Mg, Na, Cl, Fe, Zn, Cu, Mn) in two cultivars of sunflower. The trials were carried out on saline (EC = 7.6 dS m-1) calcareous soils taken from Eshtehard (Karaj) region of Iran. In a factorial trial and completely randomized design (CRD), three levels of arbuscular mycorrhizal inoculants (non inoculation, inoculation withGlomus etunicatum and Glomus intradices) and four levels of Pseudomonas fluorescensinoculants (non inoculation and inoculation with Pseudomonas fluorescens strains 4, 9, 12) in two cultivars of sunflower with four replications per treatments were applied. Results revealed that all of the treatments increased the N uptake in Euroflor cultivar. Moreover, in Euroflor cultivar, inoculation with Pseudomonas fluorescens strains 9 and co-inoculation of Pseudomonas fluorescens strains 4 and Glomus intradices made a significant different in phosphorous uptake, while did not make any significant change in the Master cultivar. However, bacterial and fungal treatments significantly (P < 0.05) increased uptake of micro nutrients such as Fe, Zn and Mn.

Problem Statement: Drought stress as a major adverse factor can lower leaf water potential, leading to reduced turgor and some other responses and ultimately lower crop productivity in arid and semi arid zones. Sunflower is one of the main oil seed crops in Iran, where drought stress is the most limiting factor. Drought stress tolerance requires the activation of complex metabolic activities including ant oxidative pathways, especially Activated Oxygen Species (AOS) and scavenging systems within the cells which can contribute to continued growth under drought stress. Approach: To evaluate the effect of limited irrigation systems and potassium fertilizer on seed yield, some antioxidant enzymes and lipid per oxidation biomarker (MDA), the crop was sown in the Research Farm of College of Agriculture, Islamic Azad University, Karaj Branch in 2009. The experimental treatments were arranged as split plots based on a Randomized Complete Block Design with three replications. The main plots were allocated to three different irrigation regimes. The irrigation regimes comprised of: Full Irrigation (IR1), Moderate drought stress (IR5) and Severe drought stress (IR2). The subplots were allocated to four potassium chemical fertilizer (potassium nitrate) consisting of K1 = 25, K2 = 50, K3 = 75 and K4 = 100% recommended. Results: Plants under drought stress and potassium levels showed a significant increase and decrease, respectively, in SOD, CAT and GPX activity and MDA in compared to control plants. In this context, plants with higher levels of potassium showed higher resistance to drought stress conditions and higher yield and dry matter allocation to grain filling process i.e. harvest index. Results of this study suggested that drought stress leads to production of oxygen radicals, which results in increased lipid peroxidation (MDA biomarker) and oxidative stress in the plant. Conclusion: The scavenging of AOS by the scavenging system especially by SOD, CAT and GPX was done well and damage to membranes or MDA was controlled at higher levels of potassium.

The stress of soil compaction, because of using agricultural machinery, may provide conditions such as limiting nutrient uptake, not suitable for plant growth. Here we hypothesized that using arbuscular mycorrhiza (AM, plant symbiotic fungi), as a biological method, may overcome the stress of soil compaction on wheat (Triticum aestivum L.) growth by enhancing nutrient uptake. Soil surface layer of the Experimental Research Field of Soil and Water Research Institute in Karaj, Iran, was sieved, sterilized, and compacted at 10 kg pots in two experiments. At seeding wheat seeds were inoculated with different species of Glomus fungi with different origins. Shoot nutrient uptake of N, P, K, Fe, Mn, Zn, Cu was determined. Soil sterilization significantly increased the nutrient uptake of mycorrhizal wheat even at the highest level of compaction. Even under compacted conditions, increased P uptake, due to AM inoculation had an important role to alleviate the stress. This novel finding may indicate the important role of AM to overcome the stress of soil compaction on wheat nutrient uptake, the independency of AM origin on their functionality, and the great importance of managing soil biological communities in agricultural systems.

Soil compaction is of great importance, due to its adverse effects on plant growth and the environment. Mechanical methods to control soil compaction may not be economically and environmentally friendly. Hence, we designed experiments to test the hypothesis that use of plant symbiotic fungi, arbuscular mycorrhiza (AM) may alleviate the stressful effects of soil compaction on corn ( Zea mays L.) growth through enhancing nutrient uptake. AM continuously interact with other soil microorganisms and its original diversity may also be important in determining the ability of the fungi to cope with the stresses. Hence, the objectives were: (1) to determine the effects of soil compaction on corn nutrient uptake in unsterilized (S1) and sterilized (S2) soils, and (2) to determine if inoculation of corn with different species of AM with different origins can enhance corn nutrient uptake in a compacted soil. Using 2 kg weights, soils (from the field topsoil) of 10 kg pots were compacted at three and four levels (C1, C2, C3 and C4) (C1 = non-compacted control) in the first and second experiment, respectively. Corn (cv. 704) seeds were planted in each pot and were inoculated with different AM treatments including control (M1), Iranian Glomus mosseae (M2), Iranian G. etunicatum (M3), and Canadian G. mosseae , received from GINCO (Glomales In Vitro Collection), Canada (M4). Corn leaf nutrient uptake of N, P, K, Fe, Mn, Zn and Cu were determined. Higher levels of compaction reduced corn nutrient uptake, however different species of AM and soil sterilization significantly increased it. The highest increase in nutrient uptake was related to P (60%) and Fe (58%) due to treatment M4S2C3. Although it seems that M3 and M4 may be the most effective species on corn nutrient uptake in a compacted soil, M2 increased nutrient uptake under conditions (C3 and C4 in unsterilized soil) where the other species did not. Through increasing nutrient uptake AM can alleviate the stressful effects of soil compaction on corn growth.

Summary Sustainable agriculture uses nature as the model in designing agricultural systems. Because nature consistently integrates her plants and animals into a diverse landscape, a major tenet of sustainable agriculture is to create and maintain diversity. The effects of earthworm inoculation (Pheretima sp., Ew), arbuscular mycorrhizal fungi (Glomus mosseae, AMF) and mixed cropping systems on forage yield, mycorrhizal colonization rate, nitrogenase activity (NA) of free-living rhizosphere bacteria, soil microbial biomass (SMB) carbon, and the growth of clovers were studied at various mixed cropping ratios of berseem clover (Trifolium alexandrinum L., B) to Persian clover (Trifolium resupinatum L., P) (B:P=1:0, 3:1, 1:1, and 1:3). The effects of AMF and Ew on plant yield were positive. Mixed cropping gave more stable yields than monoculture. The greatest mycorrhizal colonization rate was observed at a B:P ratio of 1:1 with a combined AM+Ew inoculant. With the AMF+Ew inoculant, the greatest NA of free-living rhizosphere bacteria was observed with B:P=3:1. Although Ew had no significant effect on SMB, AMF increased SMB from 256 to 444 mg carbon kg−1. The greatest SMB (379 mg kg−1) was observed at B:P=1:1. The greatest nitrogen accumulation in the aboveground biomass, 31.5 mg g−1 forage dry matter, was obtained with mixed cropping (B:P=3:1) in the presence of the AMF+Ew inoculant. A combination of AMF, Ew, and mixed cropping increased the yield, mycorrhizal colonization rate, SMB, and nitrogen uptake of the clover plants, confirming the positive effects of diversity on an agriecosystem.

Summary We conducted this study because of the importance of salinity in many parts of the world, and because almost all research regarding the effects of arbuscular mycorrhiza (AM) on plant growth under salinity have been conducted under greenhouse conditions. The hypothesis was that, with respect to the great abilities of AM fungi under stress, they are able to alleviate salinity stress under field conditions. Hence, the objectives were to evaluate the effects of different species of arbuscular mycorrhizal fungi on: (1) the yield and yield components of different wheat cultivars, and (2) nutrient uptake of different wheat genotypes under field saline conditions. The soil salinity of 7.41 dS/m and three AM species including Glomus etunicatum , G. mosseae and G. intraradices and wheat genotypes of Roshan, Kavir and a mutated line of Tabasi were tested. The electrical conductivity of the irrigation water was 13.87 dS/m. Under salinity, AM species significantly increased the growth and nutrient uptake of the mutated Tabasi line compared with the other genotypes, especially in comparison to the Kavir genotype. The mycorrhizal Tabasi genotype resulted in the lowest concentrations of Na + and Cl − . The influence of different species of AM on enhancing plant growth under salinity was observed in the following order: Glomus etunicatum > G. mosseae > G. intraradices . The symbiosis of Glomus etunicatum and G. intraradices with the Tabasi mutated line resulted in the highest (42.08%) and the lowest (7.55%) increases in wheat dry weight, respectively. The highest (38.3%) and the lowest (4.5%) grain yield increases were related to the symbiosis of Tabasi mutated line with Glomus etunicatum and G. intraradices , respectively. Although different species of AM can be very beneficial to wheat plants under salinity stress, it is obvious from the results of this research that Glomus etunicatum can perform more efficiently under such conditions compared with other AM species. This indicates the great importance of selecting the right combination of AM species and host plant to make cultivation under salinity even more likely.

Problem statement: In order to evaluate the effects of co-inoculation of Azotobacter and Mycorrhiza with nitrogen and phosphorus levels on yield and yield components of spring safflower, this study was carried out in the experimental field of Farahan University in Markazi province- Iran in 2006. Approach: A factorial experiment in the form of complete randomized block design with three replications has been used. Inoculation of Azotobacter (without and with inoculation by Azotobacter chroococum) and Mycorrhiza (without and with inoculation by Glomus intraradices) under different levels of nitrogen and phosphorus levels [F0 = N0+P0(kg ha-1), F1 = N50+P25(kg ha-1), F2 = N100+P50(kg ha-1) and F3 = N150+P75(kg ha-1)] on spring safflower (Carthamus tinctorius L.-cv. IL-111) have been studied. Results: In this study some characteristics such as: Harvest index, hectolitre weight, root dry weight, seed yield, mycorrhizal root colonization, number of days to maturity were assessed. Results indicated that treatment (A1M1F2) with average grain yield 1239 (kg ha-1) and treatment (A0M1F0) with average grain yield 723.7 (kg ha-1) were significantly higher than other treatments. Seed inoculation at the planting date with Azotobacter and Mycorrhiza caused increasing grain yield about 6.13% in compare with control treatment. Conclusion: Seed yield and yield components of safflower have been affected significantly by the inoculation with Azotobacter and Mycorrhiza, because these biofertilizers can fix atmospheric nitrogen and increase phosphorus availability in soil and enhanced absorb elements by safflower.

Since large areas of agricultural fields in the world become compacted every year, much effort has been made to reduce the adverse effects of soil compaction on plant growth. Mechanical methods to control soil compaction may be laborious and expensive; however, biological methods such as using arbuscular mycorrhiza (AM) may be more useful, economically and environmentally. The objectives of this study were: (1) to evaluate the effects of soil compaction on wheat (Triticum aestivum L.) growth, and (2) to evaluate if using AM of different origin can reduce the stressful effects of soil compaction on wheat growth. Unsterilized and sterilized soils, different levels of compaction and three species of arbuscular mycorrhiza were applied in four replicates. The experiments were conducted in the Soil and Water Research Institute, Karaj, Iran. Soil physical and chemical properties were determined. The AM increased wheat growth in both soils at different levels of soil compaction in both experiments. For root, shoot (P=0.1) and grain (P=0.05) dry weights increases were significant. AM enhanced root growth more than shoot growth under compaction (AM resulted in significant increase in root/shoot ratios, P=0.1). Due to its unique characteristics, AM may reduce the stressful effects of soil compaction on wheat growth, though its effectiveness may decrease with increasing compaction.

espanolLa desnutricion es un problema de salud que amenaza principalmente a los paises en via de desarrollo. La investigacion orientada al mejoramiento de los cereales por el bioenriquecimiento permite mejorar la alimentacion de la poblacion mundial en situacion de vulnerabilidad alimenticia. El objetivo de esta investigacion es evaluar distintas fuentes de nutrientes en maiz bioenriquecido en el desarrollo y rendimiento del cereal. El experimento de campo se realizo en el campo de investigacion de la Facultad de Agronomia de la Universidad Islamica Azad, Tabriz, Iran, durante 2012. El diseno experimental fue un diseno de bloques completos al azar con un arreglo factorial y tres repeticiones. Los factores estudiados fueron compost de lombriz (V0 y V1); inoculacion con Thiobacillus thiooxidans (B0 y B1), Fe quelatado en pulverizacion foliar (F0 y F1) y Zn quelatado en aplicacion foliar (Z0 y Z1). Los resultados mostraron que el rendimiento de grano de maiz mejora mediante la aplicacion de vermicompost (20,9%) y con inoculacion de Thiobacillus (13,1%). Los resultados indican que la los cultivos en vermicompost con aplicacion de Thiobacillus fueron muy eficaces en el aumento de contenido de micro-nutrientes de grano, con mejora de Fe (12,7% y 12,1%, respectivamente) y Zn (29,2% y 17,5%, respectivamente). Aunque la aplicacion Fe y Zn mejoro el rendimiento de grano ligeramente (5,8% y 8,0%, respectivamente), fueron eficaces para bioenriquecimiento maiz. Pese a que la aplicacion foliar de Fe y Zn tuvo efectos leves sobre el rendimiento de la planta, la aplicacion de Fe aumento el contenido hierro en el maiz en un 12,9%. La aplicacion de Zn aumento el contenido de Nen un 6,7%; Zn en un 12,6% y, proteina en un 7,2%. Los resultados sugieren que se debe estimular a los agricultores la aplicacion de micronutrientes para mejorar la calidad de sus productos. EnglishMicronutrient malnutrition is a threatening health issue mainly among the developing countries. Thus cereal biofortification must be under attention of researchers in addition to yield improvement in order to feed the increasing world population. In order to investigate the effects of various sources of nutrients on maize biofortification, growth and yield, a field experiment was conducted at the research station of the Faculty of Agriculture, Islamic Azad University, Tabriz, Iran in 2012. The experiment was carried out as a randomized complete block design with a factorial arrangement in 3 replicates. Studied factors (4 factors) were Vermicompost (V 0 and V1), inoculation with and without Thiobacillus thiooxidans (B 0 and B 1), Fe chelate foliar spraying (F 0 and F 1) and Zn chelate foliar application (Z 0 and Z 1). The results showed that maize grain yield was improved by application of vermicompost (20.9%) and inoculation with Thiobacillus (13.1%). Biofortification demonstrated that vermicompost and Thiobacillus were highly effective on the micronutrient content of grain, improving Fe (12.7% and 12.1%, respectively) and Zn (29.2% and 17.5%, respectively) content. Although Fe and Zn application improved grain yield slightly (5.8% and 8.0%, respectively), they were effective for maize biofortification. Although Fe and Zn foliar application had slight effects on plant yield, yet Fe application increased Fe content by 12.9%. However, Zn application increased the content of N by 6.7%, Zn by 12.6% and protein by 7.2%. Farmers must be encouraged to apply micronutrient fer-tilizers to their fields in order to increase the quality of their products.

The production and quality of rhizobial inoculants in many developing countries is limited by the availability of suitable carriers or technological limitations. Experiments were conducted to evaluate the potential of various inexpensive and widely available carrier materials. The carriers, evaluated, were: perlite with pH adjusted with calcium carbonate or charcoal, 1:4 mixtures of perlite and malt residue, sugarcane bagasse, coal, and rice husk. We also contrasted sterilisation procedures (autoclaving or gamma irradiation) and incubation after injection (with or without initial two weeks incubation at 28 °C) for these various carriers. Survival of Bradyrhizobium japonicum strain CB1809 was monitored over a period of 6 months upon storage at 4 °C. Most carriers evaluated, were able to maintain rhizobial populations of more than 1 × 10 9 rhizobia per gram of inoculant over that time period, with mixtures of perlite with either sugarcane bagasse or malt residue supporting the largest rhizobial populations and a mixture of perlite and rice husk the lowest. All carriers supported rhizobial growth over the 6 months period. Initially, rhizobial populations were greater with gamma irradiation than autoclaving, however after 6 months, this response was significant only with the perlite and sugarcane bagasse mixture. The incubation of the inoculant after injection also ultimately did not benefit rhizobial levels for any of the carriers, tested. Using simple sterilisation procedures and without incubating after injection, perlite based carriers can produce high quality inexpensive inoculants, maintaining bacterial populations of more than 1 × 10 9 /g rhizobia for at least 6 months.

Soil compaction is of great importance in agriculture, because its high levels may adversely affect plant growth and the environment. Since mechanical methods are not very efficient and economical, using biological methods to alleviate the stress of soil compaction on plant growth may be beneficial. The objectives of this study were to: (1) evaluate the effects of soil compaction on corn (Zea mays L.) growth, and (2) test the hypothesis that applying arbuscular mycorrhiza (AM) with different origins can partially or completely overcome the stressful effects of soil compaction on corn growth under unsterilized and sterilized conditions. Corn was planted in unsterilized and sterilized compacted soils, while treated with three species of AM including, Iranian Glomus mosseae, Iranian Glomus etunicatum, and Canadian Glomus mosseae, received from GINCO (Glomales in vitro Collection), Canada. Plant growth variables and soil resistance parameters were determined. AM significantly increased root fresh (maximum of 94% increase) and dry (maximum of 100% increase) weights in the compacted soil. AM with different origins may improve corn growth in compacted soils, though its effectiveness is related to the level of compaction and also to the interaction with other soil microorganisms.

Signal molecules are among the major factors required for the legume–bacteria symbiosis. The excretion of signal molecules by plants stimulates the bacterial Nod genes resulting in the production of lipochitooligosacharides (LCOs). LCOs cause root hair deformation (RHD) and induction of nodule cells division, leading to the formation of nodules. The chemical structure of LCOs determines their biochemical activities; for example, removal of the sulfate group can significantly reduce the morphogenic activities of LCOs. Stressful conditions interrupt the excretion of signal molecules by the legumes' roots and consequently the inhibition of LCO production by the bacteria. This research has studied the effect of different concentrations of LCOs on RHD of two soybean [Glycine max (L.) Merr] cultivars, AC Bravour and Maple Glen, under acidity stress. In the first experiment, two different concentrations of LCO (10−7 and 10−6M) and in the second experiment, three different concentrations of LCO (10−7, 10...

With respect to the significance of medicinal plants, testing methods, which may enhance their performance, can be important agriculturally and economically as well as from healthy points of view. Hence, grain oil content and yield components of the medicinal plant, safflower (Carthamus tinctorius L., cultivar IL-111), were evaluated in a field experiment. Treatments including co-inoculation with Azotobacter chroococcum and the Arbuscular mycorrhizal (AM) fungi Glomus intraradices at different rates of nitrogen (N) and phosphorous (P) fertilization including F0: control, F1: N50 + P25, F2 = N100 + P50, and F3 = N150 + P75 kg ha−1 were tested. The experiment was conducted in the spring of 2006 as a factorial on the basis of a completely randomized block design in three replicates. Grain oil content and yield components were determined. A. chroococcum increased plant N content. The two- (fungi and fertilization) and three-way (bacteria, fungi, and fertilization) interactions significantly affected grain oil content and weight of 1,000 grain, respectively. While chemical fertilization significantly decreased oil percentage, the bacterium and the fungus significantly increased oil percentage. However, for the oil content the combination of microbes with chemical fertilization resulted in the highest oil content. The effective co-inoculation of safflower with A. chroococcum and G. intraradices by increasing oil content and yield components suggests the effectiveness of this biological method for safflower production as well as a favorite partial replacement for N and P fertilization. The effects of biological fertilization on the enhancement of seed nutritional values may be more pronounced than chemical fertilization.

The main objective of this study was to determine the effects of vermicompost and nitrogen fixing bacteria on the quantity and quality of essential oil in dill essential oil content in seed, essential oil yield and carvone content, limonene content and dillapiole content in essential oil. The experiment was carried out at the Hamand Research Station of Damavand in 2011. Vermicompost (0, 4, 8 and 12 ton/ha) and nitrogen fixing bacteria, mixture of Azotobacter chroococcum and Azospirillum lipoferum (non-inoculated, inoculated seeds and inoculated seeds + spray on the plant base at stem elongation stage) were used as the effecting parameters. The present results have shown that the highest essential oil content in seed and carvone content in essential oil and the minimum dillapiole content in essential oil were obtained after applying 4 ton/ha vermicompost. The maximum essential oil yield was obtained after applying 8 ton/ha vermicompost. Nitrogen fixing bacteria also showed significant effects on essential oil content, essential oil yield and carvone content in essential oil. The maximum essential oil content and carvone content were obtained by using the nitrogen fixing bacteria once. The highest essential oil yield was obtained by using the nitrogen fixing bacteria twice. Key words: Dill, vermicompost, Azotobacter, Azospirillum, essential oil.

The main objective of this study was to determine the effects of biofertilizers on the morphological traits and seed yield in the anise plant height, umbel number per plant, weight of 1000 seeds, biological and seed yield. The experiment was carried out at the Hamand Research Station in Damavand in 2009. Vermicompost (0, 5 and 10 ton/ha) and phosphate solubilizing bacterium, Bacillus circulans (non-inoculated, inoculated seeds and inoculated seeds + spray on the plant base at stem elongation stage) were used as the effecting parameters. The results of present study demonstrated that the highest plant height, umbel number per plant, biological and seed yield were obtained after applying 10 ton/ha vermicompost. Phosphate solubilizing bacterium also showed significant effects on umbel number per plant, biological yield and seed yield. The maximum umbel number per plant, biological yield and seed yield were obtained using the phosphate solubilizing bacterium twice. Key words: Anise, biofertilizers, vermicompost, seed yield.

Forage legumes are used to enhance soil fertility of the agroecosystem. Understanding their effect on the agroecosystem during their growing period is essential. The objective of this field study was to evaluate annual clovers intercropping and earth- worm activity on the growth of weeds. The field experiment was carried out during the 2006-2007 growing seasons at the research farm of the Seed and Plant Improvement Institute, Karaj (Iran) involving various mixed cropping ratios of berseem clover (Trifolium alexandrinum L., B) and Persian clover (Trifolium resupinatum L., P) (B : P = 1 : 0, 3 : 1, 1 : 1, 1 : 3) with and without earthworm Pheretima sp. inoculation. Nitrogen content of plants and weeds as well as biomass was measured. Forage yield was higher in 2006 than 2007 but had similar response to cropping systems and earthworm inoculation. Total forage yield was highest in mixed cropping system (MCS). While in the first cut, the berseem sole crop (SC) tended to greatly suppress the growth of weeds, in the second cut Persian clover sole crop further suppressed weeds. The greater total crop biomass had an even higher weed suppression. Earthworm activity did not affect cut 1 but increased forage and weed biomass yield in cut 2. However in cut 1, berseem tended to greatly suppress the growth of weeds, which may be explained by the greater nitrogen accumulation in monocultures and intercrops, Persian clover in cut 2 had greater suppression on weed biomass production. Nitrogen accumulation of crops and weed increased under earthworm activity in the second cut.