(Download) "Isolation and Characterization of Nitrogen-Fixing Bacteria Nodulating Phaseolus Vulgaris in the Lower Rio Grande Valley of Texas (Report)" by The Texas Journal of Science ~ eBook PDF Kindle ePub Free
eBook details
- Title: Isolation and Characterization of Nitrogen-Fixing Bacteria Nodulating Phaseolus Vulgaris in the Lower Rio Grande Valley of Texas (Report)
- Author : The Texas Journal of Science
- Release Date : January 01, 2008
- Genre: Engineering,Books,Professional & Technical,
- Pages : * pages
- Size : 213 KB
Description
To establish a highly effective symbiosis between a legume plant and its bacterial symbiont it is essential to develop a successful program for the selection of superior strains to maximize production through [N.sub.2] fixation. Nitrogen-fixing bacteria from representative soil series of the Lower Rio Grande Valley region of southern Texas were examined for their symbiotic association with common 'Pinto' been (Phaseolus vulgaris L.). PCR-RFLP analyses of genes associated with nitrogen fixation indicated that the bacterial isolates belong to the recently described Rhizobium etli and none were identified as R. tropici. Examination of symbiotic responses of the rhizobial isolates under controlled, aseptic conditions, indicated that 20% produced effective nodula-tion, 35% partially effective, and the remaining 45% produced parastic or ineffective nodulation on the host legume. Strains UTPA-P 66, P82 and P80, each isolated from a different soil series, accounted for maximum plant response and nitrogen fixation activity. Although nodule morphology and size markedly varied among isolates, those with the highest tissue mass were associated with the highest production of school biomass. Electron micrographs of cross sections of 2-week old nodules indicated that effective bacterial cells were rod shaped, and more abundant than those enclosed in the peribacteroid membranes of ineffective nodules. To ensure adequate nodulation and [N.sub.2]-fixation, it is necessary to inoculate beans with locally isolated nitrogen-fixing bacteria, regardless of any previous history of bean cultivation. **********