Mycorrhizae are symbiotic associations that form between the roots of most plants species and fungi. mycorrhizal symbiosis increase the resistence of plants against damaging agents of plants like drough and salinity stress. Also increase biomas and as result it is effective in sustainability and extention of the plantsin most of ecosystems. Tandoureh National park with 73435 hectares is located in dry locality of the north of khorassan the natural characteristics and climatic differences between the lowlands and the heights of this park results in variety and distribution of its plants. because about 30 persent plants of park are medicinal and forms a larg part of plant population of Tandoreh Park, the study of Mycorrhizal distribution of the plants for constant extention is necessary. In this research, complete soil and plant samples was collected in 8 stations in spring and summer from 26 platt (10 x10). soil samples were taken from the top 30Cm.after transforming the samples to laboratory, the fragile roots of the plants were separated and coded. Some root pieces were used for preparing longitudinal sections manually and were stained with lactophenol cotton blue followingestablished botanical staining procedures. soil samples were used to isolate Mycorrhizal spore and sprocarps. by sucerose centrifugation method. Results of this study showed that there were 54 vasular plantspecies, which 18 species were medicine plants The most persent of medicinal plants are in following familes Gramineae, Labiatae, Crucifereae, Compositeae. Species of Glomus contributed to the mycorrhizal symbiosis. Mycorrhizal association in the medicinal plant communities characterizes the importance of such symbiotic relationship in sustainable development and explotation of plant resources.

In a greenhouse experiment tomato seedling (c.v.Cora) were inoculated with species of VA mycorrhiza (Glomus mosseae and Glomus intraradices) or left uninoculated as control plants in sterile and nonsterile with three levels of phosphorus (0, 20, 40 mg/kg). A factorial RB design was used with three factors of fungus, soil and phosphorus levels. Statistical analysis indicated that the main effect of phosphorus had significant effect on the shoot dry matter, vitamin C of fruit and percent root length colonization (RLC).The main effects of fungus on vitamin C concentration and percent RLC were significant at P< 0.01. Percent RLC was decreased significantly (P<0.05) with effect of (fungus * P level).The effect of (soil*fungus) was significant on percent RLC and vitamin C concentration of fruit. Correlation analysis between measured parameters indicated that shoot dry matter positively correlated with root dry weight and plant length (P<0.01).A positive correlation was observed between root dry matter and vitamin C content of fruit (P<0.05). Percent RLC positively correlated with vitamin C content of Fruit (p<0.01). Considering the results and necessity to reduce the rate of fertilizers application, P2 level, which is (20kg P/ha) less than the recommended rate for tomato, can be suggested without any reduction in quality of fruit as well as enhancing of mycorrhizal activity in tomato roots.    

Haloxylon sp., is a species plant growing in arid regions, specially in sand lands as a useful plant for fixing of sand dune. This plant has economical, social and environmental significance. Mycorrhizais a natural symbiosis between plant root and mycelia of fungi. This symbiosis is important for the plant under stressful: for example, water and nutrient deficiencies. Mycorrhizales symbiosis in Haloxylon was studied In natural and man-made forests of Yazd. Ardakan plain and Kavir e Daranjir Yazd province. Effects of environmental factors variation such as climate and soil on mycorrhizae were determined. Results showed that H.aphyllumm and persicum living in symbiosis with VAM Distribution and variation of mycorrhizae in natural forest was more than man-made forest In this symbiosis, the species of glomus gigasp ora and acaulospora in natural forest and species of giomus in man-made forest, were more prevalent.

For identification of arbuscular mycorrhizal fungi (AMF), in the late springs of 2004 and 2005, wheat fields in the Golestan Province (northeast of Iran near the Caspian sea) surveyed and root cores sampled. After extraction of AMF spores and staining roots, 19 AMF identified as follow: Entrophospora infrequens, Glomus caledonium, G. clarum, G. constrictum, G. deserticola, G. eburneum, G. etunicatum, G. geosporum, G. gibbosum, G. globiferum, G. intraradices" G. microcarpum, G. mosseae, G. multifoum, G. rubiforme, G. sinuosum, Paraglomus occultum, Scutellospora calospora and S. dipurpurascens. Species richness per sample was (1-) 4 (-7) and G. mosseae with 91% frequency was domain. G. eburneum, G. globiferum and S. calospora, are reported for the first time from Iran.

Mycorrhizal fungi play an important role in the water and mineral nutrients uptake improvement from soil. In order to investigate the effect of arbuscular mycorrhizal fungi on water relation of onion cv. ‘Red Azarshahr’ under three irrigation intervals in two soil condition (sterile and unsterile) in a greenhouse pot experiment carried out in the University of Tabriz, Tabriz, Iran. Three preinoculated onion seedling in nursery with Glomus versiforme, Glomus intraradices and Glomus etunicatum and uninoculated seedling as a control were transplanted to the pots filled with 7 kg soil. Plants were irrigated to the field capacity every 7, 9 and II days. Along trial period, leaf relative water content (RWC), osmotic potential and free proline content were measured, then leaf potential adjustment were computed. The results indicated that, nonmycorrhizal onions had significantly higher RWC than mycorrhizal ones. Mycorrhizal onions showed lower osmotic potential and free proline than control plants, so mycorrhizal colonization improved osmotic adjustment. It was concluded that mycorrhizal onions could reduce water deficit stress by lowering leaf osmotic potential through improving absorption and accumulation of mineral solutes that enable plants to improve osmotic adjustment to uptake water from drying soil.