TITLE:
Phenotypic, Stress Tolerance and Plant Growth Promoting Characteristics of Rhizobial Isolates from Selected Wild Legumes of Semiarid Region, Tirupati, India
AUTHORS:
Y. Bhargava, J. S. R. Murthy, T. V. Rajesh Kumar, M. Narayana Rao
KEYWORDS:
Wild Legumes, Rhizobia Characterization, Stress Tolerance, Plant Growth Promotion
JOURNAL NAME:
Advances in Microbiology,
Vol.6 No.1,
January
21,
2016
ABSTRACT: Rhizobia
are vital for nitrogen input, fertility of soil and legume plant growth.
Knowledge on rhizobial diversity from arid and semiarid areas is important for
dry land agriculture in the context of climatic change and for economic
utilization. This study provides morphological, biochemical, stress tolerance
and plant growth promoting characteristics of fifteen rhizobial isolates from
the nodules of same number of wild legumes and one isolate from cultivated Arachis hypogea from semi-arid region,
Tirupati. The bacterial isolates were confirmed as rhizobia based on colony
morphology and biochemical tests. Based on the colour change of YMA-BTB medium,
eight isolates were identified as slow growers and six were fast growers. The
isolates differed in growth pattern, colony morphology, antibiotic resistance
at higher concentrations and uniformity in utilization of carbon and nitrogen
sources. The isolates are tolerant to NaCl up to one percent, displayed normal
growth at temperatures 28℃ - 30℃, at neutral pH and
poor growth at pH 5and 9. The isolates varied in the production of EPS and IAA,
positive for phosphate solubilization and siderophore formation. This
functional diversity displayed by the isolates can be utilised for the legume
crop production by cross inoculation.