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(UMI)AAI9541400
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AAI9541400
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UMI
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UMI
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Bryan, James Alfred.
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Leguminous trees with edible beans, with indications of a rhizobial symbiosis in non-nodulating legumes
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[electronic resource]
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1995
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1 online resource (310 p.)
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Source: Dissertation Abstracts International, Volume: 56-08, Section: B, page: 4080.
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Adviser: John C. Gordon.
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Thesis (Ph.D.)--Yale University, 1995.
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Access is restricted by licensing agreement.
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The combination of atmospheric nitrogen-fixation with perennial soil cover and with the production of food makes leguminous trees with edible beans a potentially important resource for sustainable land use. Although numerous leguminous trees have long been known to produce beans for human consumption, no full account of this resource could be found. By combining a search of literature with herbarium studies, 277 species of leguminous trees with edible fruits were identified, and their growth habits, habitats and food uses described.
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The generally accepted method for distinguishing nitrogen-fixing from non-nitrogen-fixing legumes is to examine the root system for nodules. Of the identified species, 132 had been examined for nodulation; many ($>$30%) do not form root nodules and are generally presumed not to fix atmospheric nitrogen. They are therefore considered of questionable value for soil enrichment.
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Examining roots for nodules is difficult, imprecise and, in many cases, prohibitively disruptive. I therefore devised studies to determine distinctions, other than the presence or absence of root nodules, between nitrogen-fixing and non-nitrogen-fixing leguminous trees.
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Plastic chambers were developed to permit microscopic observation of interactions between introduced rhizobial bacteria and the living roots of non-nodulating leguminous tree seedlings. The bacteria were observed to attach to root hairs of non-nodulating leguminous trees and appeared to merge with the root hair cell walls. Infection threads were formed, as in nodulating legumes, suggesting a possible rhizobial symbiosis, and nitrogen-fixation, in non-nodulating legumes.
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After these observations, three approaches were initiated to explore the possibility of this symbiosis: sectioning and staining non-nodulating roots for light microscopy; an assay of nitrogenase activity through root gas exchange (acetylene reduction); and scanning electron microscopy (SEM) of root sections. When initial experiments with all three methods supported the possibility of a non-nodular endosymbiosis, roots of additional species were examined with SEM, to determine the possible range of such a symbiosis within the Leguminosae. The results of these SEM investigations indicate that a non-nodular rhizobial symbiosis probably extends to all three subfamilies of the Leguminosae.
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Access is available to the Yale community
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Biology, Ecology.
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Agriculture, Forestry and Wildlife.
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Yale University.
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Dissertation Abstracts International
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56-08B.
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Gordon, John C.,
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advisor
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Ph.D.
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1995
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Online resource
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Online thesis
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https://yale.idm.oclc.org/login?URL=http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9541400
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Yale Internet Resource
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Yale Internet Resource >> None|DELIM|10142596
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online resource
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2011-07-12T17:19:28.000Z
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http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:9541400