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Selection and Inoculation of Nitrogen Fixing Bacteria in Toona Sinensis

Author: ChenFenFei
Tutor: WuRuoZuo
School: Fujian Normal University
Course: Developmental Biology
Keywords: Toona sinensis Nitrogen fixing bacteria Environmental factors Bacterial fertilizer Nitrogen-fixing bacterial fertilizer carrier Bamboo charcoal
CLC: S644.4
Type: Master's thesis
Year: 2007
Downloads: 155
Quote: 0
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Abstract

Toona sinensis is an unique Chinese fast-growing timber specy with highnutritional value, medicinal value, economic value and ecological benefits, which canbear low temperature, drought environment and various soil conditions. But it has greatdemand for nitrogen fertilizer, so large-scale of nitrogen fertilizer must be applied inplanting Toona. However, the excessive use of fertilizers will not only increase forest cost,but also cause water pollution, influence health and disrupt the ecological balance.Therefore, it is time to find new path of biologic nitrogen fixation to increase the level ofnitrogen vegetable supply and promote the growth of Toona, but there has not correlativereporting of nitrogen fixation study on Toona.It has been found that there existed associative diazotrophs in Toona for the firsttime. The two strains with high nitrogenase activity were selected from rhizosphere, rootsurface and inner root of Toona, which were named A1 and C9 respectively. Theappraisal result of WIPEK32 appraisal instrument indicated that bacteria A1 may beRahnella aquatilis and C9 might be Enterobacter intermedius, but the result needed tobe further confirmed on molecular biology to ascertain their taxonomy position.The applicability to diverse environmental factors, such as the changes oftemperature, pH, carbon sources, ammonium concentration and osmotic pressure werestudied by comparison of the growth rate of nitrogen fixing bacterium A1 and C9.Theresults indicated that the strains A1 and C9 could easily adapt to different cultuaralconditions. They could propagate quickly and fix nitrogen at a temperature range of 0℃to 50℃, make use of various carbon sources and have a strong endurance to ammonium.Their difference was that the azotobacter A1 adapted well to neutrality partial to sourenvironment and its growth would be seriously restrained by high osmotic pressure,whilethe azotobacter C9 adapted well to neutrality partial to alkaline environment and had astrong endurance to high osmotic pressure, but its nitrogenase activity was distinctlyrestrained. The nitrogenase activity of strain C9 was correlated positively with its growthrate, in other words the higher bacteria nitrogenase activity, the eugoniclier it growed. Inoculating nitrogen-fixing bacterial fertilizer could distinctly promote thegrowth and N,P,K content of young Toona, which probably because that associativenitrogen fixing bacteria could improve the nitrogen concentration in plant, stimulate thegrowth of plant roots and absorbtion of water and mineral substance, but the mechanismneed to be further studied. There existed difference in the effect of different disposal, thatwas the effect of using the azotobacter A1 is better than using C9; When inoculated onseedling stage, the effect was better than inoculated on seed germinating stage, of whichthe difference reached to remarkable significant level; the effect of selecting bamboocharcoal as nitrogen-fixing bacterial fertilizer carrier was better than selecting pedite.

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