Viabilidade da conservação de estirpes de rizóbio por diferentes condicionadores líquidos

Abstract

This study had for objective to evaluate the growth kinetics and characteristics morphophysiological and symbiotic strains of rhizobia of four, front the conditioning different liquids. The experiment was composed of four strains (two of the strains of Rhizobium tropici (SEMIA 4077-SEMIA 4080) and two of Bradyrhizobium japonicum (SEMIA 5079-SEMIA 5080), respectively for bean (Phaseolus vulgaris) and soybean (Glycine max), three conditioning (NaCl 0,1%, glicerol 20% and carboximetilcelulose 0,2%) more fresh bacteria, that you/they were grown close to each evaluation period. After the growth period in liquid middle YM 0,5 mL of the bacterial broth of each strains was transferred for tubes with capacity for 2 mL, containing 1,5 mL of each conditioning liquid and maintained in room temperature by 180 days. After the accomplishment of the different formulations for the conservation of the strains, it was made the counting of UFC that contained 108 cells of the rhizobia culture approximately using serial dilutions and the method of the drop. During the experiment, readings were accomplished in the time 0, 1, 7, 15, 21 days after the conservation, following for monthly samples 30, 60, 90, 120, 150, 180 days. The efficiency symbiotic was evaluated in the periods of 15, 60 and 120 days after the conservation in bean plants and soy. The results allow to observe that the concentration of viable cells varied among the preservantes. The preservante NaCl 0,1% maintained the concentration of viable cells around 107 and 108 UFC mL-1 for the strains SEMIA 4077, 5080 and 5079 for up to 180 days of conservation and it nodulation to the 15 and 120 days of conservation for the strains SEMIA 4077 and SEMIA 4080, when inoculated in bean seeds. The conditioning Glicerol 20%, didn't present desirable characteristics for a good conservation method with the strains SEMIA 4080, SEMIA 5079 and SEMIA 5080. The carboximetilcelulose was promising for the conservation of the ancestries SEMIA 4077 and SEMIA 5079 in room temperature. Nodulation was influenced by the preservative used. In all of the preservantes there was decrease in the number of nodules during the conservation period. With base in the results the conditioning liquids NaCl 0,1% and Carboximeticelulose 0,2% were the one that got maintain the cells of the strains for a period of short period, besides preserving the characteristics morfofisiológicas of the strains of Rhizobium and Bradyrhizobium.