الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Phosphate solubilizing microorganisms have become more important and relevant in P fertilizer management and application. Total soil P has accumulated from Pfertilization and mismanagement; whereas soluble P has become less available with the increase in P fertilization in soil. The efficacy of different PSM has been difficult to compare because of the diverse results achieved with different methods, media or even formulations. The main objective of this thesis is to isolate P solubilization fungi, which not only assimilate phosphorus from insoluble forms of phosphates, but they also cause a large portion of soluble phosphates to be released in quantities in excess of their requirements under salinity conditions The features of the findings are outlined below 1. 20 isolates were obtained from the soil samples on using the sample on Pikovskaya’s medium. 2. Four isolates from Metobas, Kafr El-Sheikh Governorate (M1 to M4), 6 isolates from Desouk, Kafr El-Sheikh (D5 to D10) three isolates from Kafr El-Sheikh (Kh11 to Kh13), 5 isolates from Qutur1-Gharbia Governorate (Q14 to Q18) and two isolates from Qutur2 (Q19 and Q20).Out of all the 20 fungi isolated from the salinity soils, only ten fungi showed significant zone of P solubilization, 2 from Metobas (M3 and M4), 3 from Desouk (D6, D8 and D9), 4 from Qutur1 (Q15, Q16, Q17 and Q18) and one from Qutur2 (Q20). 3. It was noticed that the production of phosphatase decreased from 3rd to 5th day in case of isolates M3, D6, D9, Q18 and Q17 but phosphatase increased from 3rd to 5th days in case of strains M4, D8, Q15, Q16 and Q20. SUMMARY AND CONCLUSIONS 123 4. Some isolates showed a high solubilization capacity for higher NaCl concentrations as in the case of the M3, D9 and Q15 and that solubilize more at 2% of NaCl (58.77, 78.73 and 88.50 mg/ml, respectively). the same results were observed with isolate D9 and Q17 at 4% of NaCl (75.80 and 78.54 mg/ml, respectively). 5. A negative significant correlation (r = -0.6758) was observed between the solubilization of phosphate and decreasing pH of the medium . 6. Based on it’s morphological and 18S rRNA gene sequence analysis, the two isolates designated as D9 and Q17 were identified as Penicillium oxalicum and Penicillium expansum, respectively. 7. The best media formulation for the isolates was found MPVK medium proved to be most cost effective without compromising the solubilization. Therefore for further studies MPVK medium was used. 8. The optimum condition for the fermentation production of P. oxalicum and P. expansum was achieved maximum solubilization of RP and TCP were observed after 6 and 7 days of incubation by P. oxalicum (67.0 mg L-1) and P. expansum (46.2 mg L-1), respectively, the content of soluble P increased with the increase of shaking speed from 100 up to 160 rpm, The maximum content of soluble P was recorded at 30°C, the initial pH 6.5 for P. oxalicum and initial pH 7.0 for P. expansum, The obtained results showed that glucose was the best followed by fructose and xylose for the two tested fungi in phosphate solubilization, (NH4)2SO4 was found to be best in reducing the medium pH to 3.75 and simultaneous solubilization P, the concentration of RP and TCP added to the growth SUMMARY AND CONCLUSIONS 124 medium until 2.0 and 2.5 g L-1, for P. oxalicum and P. expansum respectively. 9. Penicillium expansum showed a higher soluble P releasing ability than D9 with RP source than TCP source. However, Penicillium oxalicum showed a higher soluble P releasing ability than Q17 with TCP source than RP. 10. P. oxalicm solubilized RP under salt stress up to 5% but P. expansum solubilized TCP under salt stress up to 5%. 11.The plant height, shoot and root length of canola plants increased significantly with dual inoculation with superintend and fungal spores compared with single inoculation and control at 60 days after planting. 12. Single inoculation with Penicillium oxalicum and Penicillium expansum increased significantly plant height in the presence of recommended dose of SSP compared to control. Similarly, the single inoculation with the each fungal showed the same trend in plant height in the presence of full dose of RP or TCP. Meanwhile, no significant increase was observed in the inoculation with extract of either Penicillium oxalicum and Penicillium expansum in the presence of SSP. 13.Among all single and dual inoculation treatments in generalroot and shoot dry weight of canola plants at 60 DAP, D9 (33.19 g) has found to be statistically superior over the rest of all other treatments, which was followed by D9+EX (32.84 g) and Q17 (25.87 g) which was on par with SUMMARY AND CONCLUSIONS 125 each other. The combined inoculation treatment (D9+ EX) has recorded significant highest R:S followed by Q17 and Q17+EX. 14. The single inoculation with Penicillium oxalicum and Penicillium expansum in fertilizers with SSP or RP or TCP recorded the highest significantly increment of P content in the plant of canola, compared to uninoculated control. In case of nutrient uptake, single inoculation treatment with either Penicillium oxalicum and Penicillium expansum in the fertilizer of RP or TCP with recorded significantly highest P uptake (mg plant-1) compared to all other treatments. 15. The two tested fungi in the form of single or extract or both inoculum significantly increased the total counts of PDM at all sources of mineral phosphate fertilizer. Conclusions The results obtained on agar plates and in liquid media amended with either sparingly soluble phosphates or rock phosphates showed the real aptitude of the two Penicillium isolates in mobilizing important amounts of phosphorus from insoluble phosphate sources. The efficiency of isolates were assessed on plates through the solubilization index that is a quick way to characterize and select strains for their phosphate solubilizing activity. Liquid culture experiment involved SUMMARY AND CONCLUSIONS 126 the P measurement as well as the pH of the corresponding media. All the two strains were capable to mobilize important amount of phosphorus from the insoluble rock phosphate and tricalcium phosphate sources, and the pH of the corresponding media were correlated to the amount of the solved P. These strains can be used for the solubilization of fixed phosphates into the agricultural soil systems. However, the selection of phosphate solubilizing Penicillium strains as possible inoculation tools for phosphate-deficient soils should focus on the integral interpretation of laboratory assays, greenhouse experiments as well as field trials. According to the present research, mixing rock phosphate with sulfur and organic matter significantly increased canola growth and oil production relative to the control treatment. In the meanwhile, inoculation of the above mentioned treatments with P solubilizing bacteria and Thiobacillus sp. resulted in higher plant growth. According to the results, and with respect to the presence of high amount of sulfur and rock phosphate resources in the country and other parts of the world, it is suggested that in soils with different buffering capacities, and for different crop plants different combinations of sulfur and rock phosphate with P solubilizing and sulfur oxidizing bacteria be used. It is also very important to compare their efficiencies, when combined with chemical P fertilizers so that the use of P fertilizer can be optimized.