Diazotrophic bacteria in star flowers

Abstract

This study evaluated the occurrence and density of associative diazotrophic bacteria in the rhizosphere, collar, roots and leaves of Syngonanthus elegans (Bong) Ruhland (Goldenfoot) and Syngonanthus aciphyllus (Mini-skirt). These species are able to grow in poor soils. Five samples, with 25 plants both of S. elegans and S. aciphyllus, each were collected in Soberbo stream, Diamantina-MG, Brazil. The occurrence and the density of diazotrophic bacteria were evaluated by the most probable number (MPN) method in semi-selective N-free media NFb, LGI, JNFb, and JMV. In general, for both species, a high density of diazotrophic bacteria was observed in all of the microenvironments evaluated. The density was greater in S. elegans than in S. aciphyllus. The associative occurrence of diazotrophic bacteria in S. elegans and S. aciphyllus can contribute to plant adaptation to low fertility soils.