AuthorSHOUSHTARI, NASTARAN HAKIM.
AdvisorPepper, Ian L.
MetadataShow full item record
PublisherThe University of Arizona.
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
AbstractA native desert Rhizobium, AZ-M1, was isolated from a nodulated mesquite tree (Prosopis juliflora var. velutina) following inoculation of mesquite seed with a desert soil. This strain and a selected commercial strain (31A5) were used in a greenhouse study to determine their N fixation efficiency against applied N fertilizer. Strain AZ-M1 was a more efficient N fixer than 31A5. The survival rate of the two strains was tested in three different desert soils in a controlled laboratory study. The native strain AZ-M1 grew and survived in the soils over a period of one month. The commercial strain did not grow and the population decreased from 10⁸ cells gm⁻¹ of dry soil to below 10⁴ cells after 14 days. Soil factors affected survival of both strains. The competitiveness of the two strains was compared in a greenhouse experiment. The native isolate out competed strain 31A5 in nodule occupancy regardless of cell number when applied as a mixed inoculant. A high incidence of double occupancy was found in the root nodules when double strain inoculants were applied. The two rhizobia were fast growing rhizobia, lowering the pH of a defined medium. Strain AZ-M1 showed a high intrinsic resistance to 3 antibiotics among 12 tested. Strain AZ-M1 has been shown to be highly effective, fairly competitive and survive better in desert soils than strain 31A5.
Degree ProgramSoils, Water and Engineering