SURVIVAL OF BRADYRHIZOBIUM SP UNDER DIFFE RENT GROWTH TEMPERATURES

The survival of Bradyrhizobium sp. under different growth temperatures , as well as the effectiveness of that strain in relationship to the l ongevity of the inoculant were evaluated through the study of the beha viour of the strain Bradyrhizobium by observing the cellular growth an d the pH evolution. The bacterial suspension was multiplied in ferment ator at the temperatures of 28 degrees C and 37 degrees C in YEMA medi um. The substrates were: diatomite, diatomite + soil 20% and peat. The evaluation of viable cells was carried out by the methods of plate di lution and plant infection, with sampling at the intervals of 0, 15, 3 0, 60, 120 e 240 days of storage at a temperature of 5 degrees C. The strain grown under 28 degrees C showed a population of 10(9) cells/ml after 72 hours of process, and remained constant up to 240 days in all of the substrates. Under the temperature of 37 degrees C, within 72 h ours of process the population was 10(5)-10(6) cells/ml. For the peat, excellent survival was observed even at this low initial concentratio n, detected in less than 30 days of storage. Concentrations of 10(9) c ells/g of peat remained constant up to 240 days. In the other vehicles the values reached 10(7)-10(8) cells/g.