Morfofisiologia de isolados de rizóbios de fabáceas forrageiras do semiárido pernambucano

Abstract

This study aimed to characterize Morphophysiologically native Rhizobia of Fabaceae forage Caatinga, Mimosa tenuiflora (Willd) Poiret, (Jurema preta), Macroptilium atropurpureum (OC.) Urb (Siratro) and Desmanthus pernambucanus (L.) Thellung (jureminha) in selected soils in areas of Caatinga located in the municipalities of Sertânia, Arcoverde and São Bento do Una- Pernambuco. Soil samples were collected at random in three areas in profile 0 to 20 cm depth, designed for the planting of Fabaceae, with the purpose of producing nodules. After obtaining the nodules and replication of the bacteria in the laboratory colonies were characterized as the time of growth and cultural characteristics of Rhizobia isolates. Tests were also made in vitro tolerance of Rhizobia isolated in different variations in salinity, temperature and pH. Based on physiological data we calculated the diversity indices, evenness, dominance and species richness, then dendrograms generated by the UPGMA algorithm. In cultural evaluation revealed that the isolates showed the hallmarks of flat lifting colonies, low to moderate production of exopolysaccharides, color ranging from white to cream and smooth surface in accordance with each individual. Physiological tests of the abiotic stress resistance showed that the natives isolated from Mimosa tenuiflora were more resistant when grown in soils from the municipality of Sertânia and isolates Macroptilium atropurpureum and Desmanthus pernambucanus had high resistance to high temperatures, regardless of place of farming. For Species diversity analysis can be seen that the Caatinga area evaluated in São Bento do Una showed lower species diversity. Native rhizobia in the areas of collections in Pernambuco semiarid feature high resistance to abiotic stress caused by temperatures up to 40 °C, variations in salinity and pH.