Data/hora: 20/05/2024 15:38:49

Biblioteca(s): | Embrapa Soja.
Data corrente: | 22/12/2005
Data da última atualização: | 22/12/2005
Autoria: | HUNGRIA, M.; CAMPO, R. J.; MENDES, I. C.
Título: | Reinoculation increasing soybean grain yield in Brazil.
Ano de publicação: | 2005
Fonte/Imprenta: | In: WANG, Y. P.; LIN, M.; TIAN, Z. X.; ELMERICH, C.; NEWTON. W. E. (Ed). Biological nitrogen fixation, sustainable agriculture and the environment. Dordrecht: Springer, 2005. p. 315.
Série: | (Current Plant Science and Biotechnology in Agriculture, 41).
Idioma: | Inglês
Notas: | Proceedingsof the 14th International Nitrogen Fixation Congress.
Conteúdo: | Soybean (Glycine max) was introduced into Brazil at the end of the century, but commercial crop expansion started only in the 1960s, such that today the country is the second largest grain producer of this legume. Biological nitrogen fixation (BNF) has always been a significant concern and programs for both strain selection and identification of plant genotypes with superior symbiotic performance began in the late 1960s, and remain a major focus. Now, there are four strains officially recommended as inoculants in Brazil: Bradyrhizobium elkanii SEMIA 587 (from 1968-1975 and then since 1979) and 29W (= SEMIA 5019) (rsince 1979), and B. japonicum strains CPAC 7 (=SEMIA 5080) and CPAC 15 (=SEMIA 5079) (both since 1992). However, today most soils (>90%) cropped with soybean in Brazil have high populations of Bradyrhizobium (10 ³ cells g-¹ of soil or higher), established from previous inoculations, thus the need for reinoculation should be investigated. Field trials were performed in four Brazilian states, representing the main cropping areas. Inoculant treatments included single or combined recommended strains in a peat-based carrier, at a concentrattion of 10 8 cells g-¹ of inoculant, applied at a rate of 500 g of inoculant 50 kg-¹ seeds. Trials always included non-inoculated controls, with or without N-fertilizer (200 kg of N ha-¹, split at sowing and at flowering time). 20 field trials were performed in a 14-year period, and statistically significant increases were obtained due to reinoculation. Mean grain yield increases were 8%, representing a major contribution to the crop. Noteworthy are that yileds higher than 4,000 kg ha-¹ were obtained in BNF-dependent plants and that yield responses to inoculation occurred in a majority of soils having more than 10 ³ indigenous rhizobia g-¹ soil. Rates of BNF of up to 300 kg of N ha-¹ , and providing up to 94% (Estimated by the N-ureide technique) of total plant N were observed. Benefits from N release of the following crop were also observed 9about 20-30 kg N ha-¹ ). Starter (30 kg N ha-¹ ) and pre- or post-flowering (50 kg N ha-¹ ) N-fertilization did not increase yield,  so emphasizing biological efficiency.
Categoria do assunto: | --
Registro original: | Embrapa Soja (CNPSO)
Exemplares: | CNPSO - (25861-1) - UPC - SP - -- - 10718 -  - 10718 - DIS