Tolerance of Clover Rhizobia to Heat and Desiccation Stresses in Soil
- A. P. Trotman and
- R. W. Weaver
The ability to withstand desiccation and heat is an important attribute of Rhizobium leguminosarum bv. trifolii for inoculation of clover (Trifolium spp.). Desiccation and heat tolerances of 10 commercial strains of rhizobia and 150 isolates from 15 clover fields in Texas were determined by studying survival of rhizobia in soil incubated at 37°C and −30 J kg−1 water potential for heat stress and 28°C and −1.5 kJ kg−1 water potential for desiccation stress. Fewer commercial strains were tolerant to these environmental stresses than field isolates. Of 150 field isolates, 31 and 19 were able to maintain at least 1% of their initial populations for 1 wk under desiccation and temperature stresses, respectively. Six of the field isolates were tolerant to both stresses, and three of these were effective in N2 fixation. Only one of 10 commercial strains were tolerant to either stress, and none was tolerant to both stresses. Rhizobia in inoculants are usually selected on their ability to fix N2, but it appears that there is good genetic material in field populations for developing strains that have greater tolerance to environmental stresses.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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