Data/hora: 22/06/2024 17:22:24

Biblioteca(s): 	Embrapa Soja.	
Data corrente: 	21/10/2005	
Data da última atualização: 	21/10/2005	
Autoria: 	HUNGRIA, M.; CAMPO, R. J.; GALLI-TERESAWA, L. V.; FERREIRA, M. C.; CHUEIRE, L. M. O.	
Título: 	Genetic structure of soybean Bradyrhizobia populations in Brazil.	
Ano de publicação: 	2004	
Fonte/Imprenta: 	In: INTERNATIONAL SYMPOSIUM ON MICROBIAL ECOLOGY, 10., 2004, Cancun. Microbial planet: sub-surface to space. Cancun: Internacional Society for Microbial, 2004. p. 1059.	
Idioma: 	Inglês	
Conteúdo: 	Soybean was introduced in Brazil in 1882 but only in the 1940s the expansion of commercial crops started. Brazilian soils are originally void of soybean bradyrhizobia therefore inoculants were brought from foreigner countries during the crop expansion period. Selection of adapted strains soon started and still continues such that today 14 million doses of inoculants containing the strains recommended by the researchers were sold in the last crop season. Analyses of soybean bradyrhizobia populations in 18 sites covering the whole Brazilian territory and including uncropped and cropped areas were performed by our group. The populations were trapped by both modern cultivars and unimproved promiscuous genotypes. The results indicated dispersion of strains from areas cropped with soybean to uncropped areas, genetic modifications due to the adaptation to the stressful conditions typical from tropical regions, such as high temperatures and low soil moisture. There are also evidences of lateral transfer of nif genes from inoculant strains to indigenous rhizobia. In most soils, after a five-year period of cropping an enormous diversity was observed among the isolates in relation to morphological, physiological, serological, genetic and symbiotic properties. The rhizobial diversity increases considerably when the period cropped with the host plant increases. The high diversity may play an important role as a biological buffer, avoiding the dominance of a particular strain, but may also limit the introduction of selected strains with higher capacity of N2 fixation.	
Thesagro: 	Bacteriologia do Solo; Rhizobium; Semente; Soja.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Soja (CNPSO)	
Exemplares: 	CNPSO - (25643-1) - UPC - SP - -- - 10626 -  - 10627 - DIS