Twenty-nine Rhizobium leguminosarum biovar trifolii strains were tested for acidity tolerance in acidified liquid medium. Only 41\ of the strains grew at pH 4.1. One acid-tolerant strain, USDA 2160, and one acid-sensitive strain, 162-X-103 from Nitragin Co., were inoculated on seeds of 'Nungarin', 'Seaton Park' and 'Clare' subclover cultivars. The inoculated and pelleted seeds were sown in potted Cluff soil with pH 5. 7. Three desiccation levels were imposed by delaying watering for 0, 15 or 30 days. Four gravimetric soil water contents (6.0, 6.6, 10.5 and 12.5\) were maintained under a greenhouse line-source sprinkler system for 7 weeks. The desiccation treatments
were more detrimental to the survival of the acid-tolerant Rhizobium strain (USDA 2160) than they were for the acid sensitive strain (162-X-103). Symbiotic effectiveness, measured as shoot dry weight, was higher with strain 162-X- 103 than with strain USDA 2160 and was comparable to the Nfertilized control at the highest water level (12.5 %). At the lower water levels (6.0, 6.6 %) symbiotic N2-fixation was more affected than N-uptake. The Rhizobium strains were able to survive and grow even at the lowest soil water level. The number of rhizobia in the soil and nodulation of the subclover plants had a correlation of 0.56.
| Identifer | oai:union.ndltd.org:UTAHS/oai:digitalcommons.usu.edu:etd-4468 |
| Date | 01 May 1987 |
| Creators | Bueno, Carmen |
| Publisher | DigitalCommons@USU |
| Source Sets | Utah State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | All Graduate Theses and Dissertations |
| Rights | Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact Andrew Wesolek (andrew.wesolek@usu.edu). |
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