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Abstract The pH of the Egyption soils are slightly alkaline and most of the Egyptian soils are poor in nutrients and require adequate amount of fertilization to sustain and improve high plant productivity. Monohydrogen phosphate (available form of phosphorus for plant) react with calcium in neutral and alkaline soils and precipitated strongly to the surface of the soil particles this reaction remove available phosphorus from soil solution. Fortunately, there are groups of soil microorganisms (phosphate solubilizing fungi) that can solubilize unavailable phosphorus forms. The need for effective and environmentally biofertilizers for agriculture as alternative way for using chemical fertilizers was increased. The present study involved three aims, the first aims is the isolation, identification and solubilization potential of phosphate solubilizing fungi from different habitats. Thirty soil samples were collected from different localities and different habitats in Beni-Suef governorate, Egypt. Total fungal counts were recorded by using dilution plate methods on Pikovskaya,s medium (PVK). Phosphate solubilizing fungi (PSF) were selected by formation of halo zone around fungal colony on (PVK) agar plate after 4 days of incubation. Out of the 146 fungi taxa isolated from different soil samples, only ten isolates showed significant zone of phosphate solubilization on PVK agar medium. The physico - chemical properties of the soil containing PSF were determined. PSF were identified morphologically and the most common genera were Aspergillus and Penicillium and Trichoderma. Trichoderma spp. have different mechanism in phosphate solubilization and not produce clear zone on agar plate like Aspergillus and Penicillium. Five species of Trichoderma were 90 isolated and screened on broth medium to be phosphate solubilizing fungi. Only thirteen soil samples from thirty soil samples collected from different localities in Beni-Suef governorate possessed PSF and this indicate that the low count of (PSF) in Egyptian soil. The isolation of PSF from saline soil refers to the ability of these isolates to high salinity tolerance and any microorganism that acidifies its external medium will show some level of phosphorus solubilizing activity. All isolates exhibit different levels of phosphate solubilizing activity on (PVK) broth medium containing tri-calcium phosphate (TCP) as sole phosphorus source. Final pH of the medium, solubilized P and dry weights of fungi were recorded. Aspergillus niger 2, Penicillium variabile and T. harzianum 301 showed solubilization activity 1.67, 0.55% and 0.32% respectively whereas the pH values of the culture filtrates were 3.6, 4.3 and 5.0 respectively. The role of mycorrhizae in phosphorus acquisition cannot be denied. Isolation and characterization of arbuscular mycorrhizal spores from different habitats in Beni-Suef governorate is the second aim of the study. Fourteen Plants collected from different localities in Beni- Suef governorate were found to be belonging to nine families. Two plant species were identified as member of liliaceae namely Allium cepa and Allium sativum and four plant species of Gramineae were identified as Triticum vulgaris, Zea mays, Sorghum sp. and Ehrharta calycina. Solanum tuberscum and Lycopersicon esculatium were collected and identified as member of solanaceae collected during this investigation. Leguminoseae, Chenopodiaceae, sclepiadceae, Umbelliferae, Onagraceae and Portulacaceace were represented by single species. 91 The study showed that the counts of (AM) spores were affected by plant species and location. Trifolium alexanderinum, Cynancum acutum, Sorghum sp., Zea mays, Anathum graveolans, Ehrharta calycina, Ludwigia stolonifera and Allium cepa showed the highest number of spores compared to other samples (40000-110000 spores Kg-1soil). In contrast Lycopersicon esculatium, Solanum tuberscum, Allium sativum, Triticum vulgaris, Portulaca oleraceae and Beta vulgaris var rapa gave the lowest density of mycorrhizal spores (17000-37000 spores Kg-1soil). Glomus was the most abundant genus during the study, it was isolated from all soil samples. Gigaspora was the second important genus, it was extracted and sieved from nine soil samples out of fourteen. Acaulospora was the third important genus, it was isolated from seven soil samples out of fourteen. Seven species were isolated and identified during the investigation Glomus fasciculatus, Glomus mosseae, Glomus etunicatus, Gigaspora nigra, Gigaspora calospora, Aculospora laevis and Entrophospora infrquens. The application of this study was conducted in pot experiment which is the third aim of the work. The aim of this experiment to evaluate the efficiency of phosphate solubilizing fungi on growth of Hordeum vulgare in prescence and absence of rock phosphate in unsterilized soil. Aspergillus niger 2, Trichoderm harzianum 301 and arbuscular mycorrhizal spores were put as individual inocula in pots. Morphological and physiological parameters were recorded on Hordeum vulgare in addition to microbiological studies on the soil of the experiment as total bacterial and fungal counts. Also, dehydrogenase enzyme activity was estimated as an important factor for microbial activity. All the previous parameters were measured at two growth intervals (30 and 60 days). The results revealed that the growth of Hordeum vulgare increased in presence of rock phosphate and 92 inoculated with PSF than non rock phosphate amended soil inoculated with PSF. T. harzianum 301 stimulated the growth of Hordeum vulgare in both case of rock phosphate and non rock phosphate amended soil. The AMF treatment showed significant increase in nitrogen, potassium and phosphorus percent when compared with other treatments. from the previous results it was concluded that rock phosphate can be added as a crude phosphate fertilizer in the soil with phosphate solubilizing fungus Trichoderma harzianum. The application of P solubilizing fungi is recommended as a sustainable way for increasing plant growth. |