Data/hora: 11/06/2024 05:41:26

Biblioteca(s): | Embrapa Agrobiologia.
Data corrente: | 27/12/2000
Data da última atualização: | 27/12/2000
Autoria: | TRANNIN, W. S.; URQUIAGA, S.; GUERRA, J. G. M.; IBIJBJEN, J.; CADISCH, G.
Título: | Interspecies competition and N transfer in a tropical grass-legume mixture.
Ano de publicação: | 2000
Fonte/Imprenta: | Biology and Fertility of Soils, Berlin, v. 32, n. 6, p. 441-448, 2000.
Idioma: | Inglês
Conteúdo: | Competitiveness of Brachiaria decumbens cv. Basilisk and Stylosanthes guianensis cv. Minerão was investigated either without root restriction or by separating their root systems with a fine mesh or a solid barrier in the presence or absence of mycorrhiza ( Glomus clarum ). Nitrogen transfer between the legume and the grass was assessed with the 15N isotope dilution technique using a relatively stable 15N-enriched soil derived from a long-term labelling experiment. During establishment, legume development was severely restricted by competition from the grass in pots without a root barrier. However, as the system became N limited, the legume became dominant due to its access to atmospheric N2 which contributed over 80% of the legume N requirements. S. guianensis was highly mycotrophic and inoculation with mycorrhiza favoured rapid establishment even in the treatments with no root barrier. Only in the presence of root barriers, either a mesh or a complete compartment separation, was the proportion of N derived from N2 fixation positively affected by the presence of the fungus. No significant direct belowground N transfer from legume to grass was observed during the lifetime of the legume suggesting that the legume maintains a highly efficient recycling under N-limited conditions. However, after cutting the shoot at ground leveI, the grass assimilated significant amounts of N de- rived from decaying legume roots. We conclude that the main pathway of  belowground N transfer from S. guianensis to associated B. decumbens occurred via de- composing roots rather than via root exudates or direct mycorrhizal hyphae transfer.
Palavras-Chave: | Arbuscular mycorrhizae vesicular; Biological nitrogen fixation; BNF; FBN; Fixação biológica de nitrogênio.
Thesagro: | Brachiaria Decumbens; Micorriza Vesicular Arbuscular; Stylosanthes Guianensis.
Categoria do assunto: | --
Registro original: | Embrapa Agrobiologia (CNPAB)
Exemplares: | CNPAB - (916-1) - UPC - SP - -- -  -  - 0022530 - DIS