modern research physics

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Microalgae are cosmopolitan microorganisms and minerals are considered as limiting factors for growth of them. In the present study cyanobacteria were isolated and indentified and also the effect of different media on their growth was examined. Consequently, two new species of cyanobacteria belonged to the family of Oscillatoriaceae were isolated and reported for the first time from Tehran province. To this end, soil samples were collected from Tehran Province in summer 2008. Samples were cultured in BBM & N8 media to evaluate the effect of nutrients on the growth of microalgae. Isolation was carried out by several subcultures. Morphological indentification was done using systematics keys and partial sequencing of 16S rRNA was used for molecular identification. The results showed that two species were recorded from Tehran Province, Leptolyngbya sp. ISC 40 Gomont and Leptolyngbya sp. ISC 25 Gomont. The collected soil samples were analyzed physically and chemically. Results indicated that BBM medium was suitable for isolation and as indicated by infertility of cultured soils, two identified species are resistance to environmental factors.

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Many pistachio cultivating areas are exposed to excess magnesium amounts. In this study, the effect of excess Mg was considered via treating pistachio var. Badami with different concentrations of MgSO4 in a pot culture experiment in the soils with VA mycorrhizal fungi according to a complete randomized block design. Total length of roots and shoots, dry weights, the number of spores produced by VAM fungi, colonizations rate of the roots to VAM and the contents of Ca, Mg, K in the roots and shoots were measured. The results showed that VAM spore number, plant dry weight and root colonization rate increased as more MgSO4 was added to the pots. The contents of Ca, Mg, K in the roots were also increased. However, the Mg content of roots was higher than that of shoots

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Alkaloids are a large group of molecules with biological, physiological and chemical activities. Plants of the genus (Podophyllaceae) are the known sources of alkaloids. In the present study the amount of total alkaloids of tubers of from two different regions of Iran, Marivan - Sanandaj and of from Sanandaj -Naghadeh was determined by spectrophotometry, on the reaction of alkaloid with bromocresol green (BCG). Moreover, the effect of some characteristicts of the soil habitat such as, soil pH, total nitrogen, potassium, altitude, texture soil, and nitrate content of tubers on the amount from total alkaloids was measured. The results of data analysis showed the significant differences between total alkaloid content of Marivan (27.12 ±1.18 mg/g D.W) with Sanandaj  (17.42 ±0.77 mg/g D.W) and of Sanandaj (15.38 ±0.65 mg/g D.W) with Naghadeh (7.4 ±0.32 mg/g D.W). Also there was a significant difference between the species in different regions other than of Sanandaj (17.42 ±0.77 mg/g D.W) with of Sanandaj (15.38 ±0.65 mg/g D.W). Furthermore, the results show that nitrate content of was higher than that of. The soil texture of Sanandaj (L. armeniaca) was loam sand and soil of the rest regions was clay loam. All of soils were mildly alkaline. Results from the effect of environmental factors on the total alkaloid content showed that with increasing amount of total nitrogen and potassium of soil and nitrate content, total alkaloids will be reduced, whereas pH, texture soil and altitude had not significant influence on total alkaloid contents