الفهرس 
Introduction
BiofertilizersOnly 14 pages are availabe for public view
 |  | from | 110 |  |  |
| | | from | 110 | | |
Abstract
In this study, 10 different colonies were isolated from rhizosphere soil samplesof soils that are different in texture collected from Aswan governorate. from these 10 colonies of primary selection 3 isolates were selected finally forfurther study on the basis of their ability to grow better and faster in Nfb semi-solid medium in screw capped testtubes. The selected isolates were M-1 (isolated from the clayey soil), and M-2 and M-3 (isolated from two samples of the sandy soil).According to Bergey’s Manual of Determinative Bacteriology (1994), considering all the identifying characteristics selected isolates were identified as Azospirillumbrasilense. Variations among the isolates in some characteristics such as colony morphology, starch hydrolysis and fermentation test indicated the different identity of the three isolates, although the observed variations are within the limits of species.This investigation included several laboratory and field experiments for studying the following specific objectives:1- Assess efficiency of the Azospirillum isolates to fix atmospheric nitrogen and production of auxin and gibberellic acid.2- Suitability of molasses of sugarcane for use as inexpensive sources of carbon and nutrients for Azospirillumgrowth under laboratory conditions.3- Studying the growth of Azospirillum (strain M-1) under fermentor conditions on diluted sugarcane molasses (75ml/l) as growth medium using different aeration rates for large scale production of biomass for inoculants preparation.4-Testing the response of field grown wheat (cv. Seds-l) to inoculation with isolated Azospirillumunder different levels of N-Fertilization.Growth curves of isolated Azospirillum strains
The curves show a short lag of less than 24 hrs. after which cells number increased exponentially with time in cultures of all isolates. The maximum growth, as indicated from viable count on plate agar medium, was reached after 4 days for isolate M-1 and M-2, and after 5 days in case of isolates M-3. The slowest growth rate was shown by isolate M-3, while the fastest growth was shown by isolate M-1.Efficiency of the isolates to fix atmospheric nitrogen:The amount of nitrogen fixed by Azospirillum strains determined by the microkjeldahl method, were 23.65, 15.32 and 19.75 mg N per gram of malate utilized, respectively These results indicate that Azospirillum strain M-1 had higher potential to fix atmospheric nitrogen compared with the other strains (M-2 and M-3).
Production of auxin and gibberellic acid by Azospirillumstrains: The amount of IAA produced were 33.57, 17.34 and 11.26 µg /100 ml culture of Azospirillumstrains M-1, M-2 and M-3 respectively , whereas, the amount of gibberellic acid (GA3) produced were 3.12, 1.56 and 0.89 µg /100 ml culture of Azospirillumstrains M-1, M-2 and M-3 respectively . The results show a great variation among the tested Azospirillumstrains in production capacities of these growth promoting substances (IAA from 33.57 to 11.26 µg /100 ml and GA3 from 3.12 to 0.89 µg /100 ml). The results also show that the strain M-1produced the highest amounts of both indol acetic acid and gibberellic acid, while the lowest amounts were produced by the strain M-3.Growth of Azospirillum on diluted molasses: The suitability of diluted molasses as inexpensive media, for growth of Azospirillumwas tested in the laboratory in batch culture under static conditions using 500 ml-Erlenmeyer flasks. As previously detailed in the Materials and Methods, the isolated Azospirillum strain M-1, was grown on the following diluted concentrations of the by-product molasses: 25, 50 and 75 ml/L of distilled water compared with Nfb semi-solid medium.The results show that viable cells count increased with time in all media, and maximum counts were recorded after 4 days in Nfb semi-solid medium. While, maximum counts were recorded after 6 days in all molasses culture concentrations. The curves also show that multiplication of inoculated cells started earlier in in Nfb semi-solid culture compared with all molasses culture concentrations. The culture of molasses dilution (75 ml/L) showed the maximum growth after 6-day incubation, almost equal to that produced on Nfb semi-solid medium. These results indicate that diluted molasses is a suitable by¬product capable, without any further additive, of supplying adequate nutrients that support good growth ofAzospirillumequals to that produced on Nfb semi-solid medium. Thus, it could be used, at the tested concentrations of 75 ml/L as cheap medium for growing and production of Azospirillum inoculants on large scale.Fermentor Experiment:
In this experiment, the effect of different aeration rates on the growth rate and viable cell production by Azospirillum strain (M-1l) on diluted molasses medium (75 ml/L). The tested air flow rate in the first fermentor (FI) was 0.5 L/min, in the second (F2) was 1 L/min, and in the third fermentor (F3) was 2 L/min. The results show that increasing the aeration rate to 2 L/min markedly reduced both the growth rate as well as the numbers of viable cells produced. Response of wheat to Azospirillum inoculation and levels of N- fertilization:
During the two successive seasons of 2013/2014and 2014/2015 , response of wheat, cv. Seds1 to inoculation with the isolated Azospirillum strains M-1, M-2 and M-3 was tested in the field using different levels of N-fertilization (40, 60 and 80 kgN/fed.).The experiments were conducted at the Experimental Farm of Center for Bio – organic Agricultural researches at Aswan which follows the ministry of Agriculture and land reclamation.The combined analysis for the data obtained on wheat growth and yield in two successive seasons showing that wheat seed inoculation with any of the isolated Azospirillumstrains (M-1, M-2 and M-3) induced highly significant increases in all measured growth parameters as well as in total and grain yields and % N in grains. Strains M-1and M-3 were more simulative than M-2 producing the highest total and grain yields.Under field conditions the rate of N-fertilization had significant influence on plant growth and yield, showing significant additive increases with the increase in N-level from 40 up to 80kg N/feddan. The maximum values recorded at the 80 kg-level were significantly higher than those recorded at the 60 kg-level for fresh weight of shoots and roots, total and grain yields and total N in grains.The two interacting factors (inoculation X N-fertilization level) showed most pronounced mutual effects at the lowest level of 40 kg N/fed. with any of the tested strains compared with the uninoculated treatment .At the higher N-fertilization levels (60 and 80 kg N/Fed.) the increases in plant growth and yield induced by the tested strains tended to decrease, yet the differences were still significant compared with the uninoculated treatment.
Azospirillum strain M-1was the most reactive at all N-levels. At the 40 Kg N-level, this strain scored the highest grain yields of 8.35 Kg/plot compared with 4.94 Kg, 7.69 Kg and 9.22 Kg grain yield/plot produced in the uninoculated treatments with, 40 ,60 and 80 Kg N/fed., respectively.. This confirms the superiority of the isolated Azospirillum strain M-1in comparison with M-2 and M-3. The results also indicate that wheat inoculation with effective Azospirillum strain could save between 20-40 Kg N-fertilizer /feddan.
References
Adam S D G: Rai An, Bergman b and Rasmussen U. 2002. Cyanobacteria insymbiosis with hornworts and liver wart; Dordrech tkluwer Academic publishers.117-85.
Alagawadi, A. R. and Krishnaraj, P. U., 1998, Field performance of two local rhizobacteria isolates in sorghum. 37th Ann. Conference of Associaiton of Microbiologists on India, Mangalore, p. 278.
Al-Khiat S. H. Ali, (2006). Effect of Cyanobacteria as a Soil Conditioner and Biofertilizer on Growth and Some Biochemical characteristics of Tomato (Lycopersicon esculentum L.)Seedlings. Thesis Submitted in partial fulfillment of the requirements of the Degree of master of Science (M. Sc.) Microbiology (Algae), King Saud University. Special Publication, 6, p: 1-4.Anond, R.C., R. Ger, M. Hazija and B.S. Kundu, 1999. Development of thermotolerant mutants ofLaz-z-marked Azospirillum lipoferum, IndianMicrobiol., 39(2): 121-123.Aslan and T. Kammash, 1997.Ariemannsolver for the Two- Dimensional MHP Quations. IM. J. NumER Methl. Fluids, Vol. 25: 953-957.
Attitalla, I. H. and Salleh, 2010. Improvement of carboxymenthyl cellulose and xylanase production by alginate immobilized trichoderma harzianum. Biotechnology, 9: 529- 532.Barberi, P. and E. Galli, 1993. Effect on wheatroot development of inoculation with an Azospirillum brasilense mutant with alteredindole-3 acetic acid production. Res. Microbiol., 144: 69-75.
Bashan, Y., Ream, Y., Levanony, H. and Sade, A., 1989, Non specific responses in plant growth, yield and root colonization of non-cereal crop plants to inoculation with Azospirillum brasilense Cd. Can. J. Bot., 67:1317.
Becking, J.H., 1985. Pleomorphism in Azospirillum pp. pp: 243-262. In: Azospirillum III Genetics, Physiology, Ecology, N. Klingmuller (Ed.) Springer-Verlag, Berlin.Beijerink MW, 1988. Die bacterien der papilionaceen- knollchen. Botanische zeitung 46: 725-735, 741- 750, 757- 771, 781- 790, 7.