Data/hora: 18/06/2024 02:20:33

Biblioteca(s): | Embrapa Semiárido; Embrapa Soja.
Data corrente: | 06/07/1994
Data da última atualização: | 01/08/2020
Autoria: | WANG, S. R.
Título: | Effect of nitrogen and other factors on plant growth responses to vesicular-arbuscular mycorrhiza.
Ano de publicação: | 1984
Fonte/Imprenta: | London: University of London, 1984.
Páginas: | 236 f.
Idioma: | Inglês
Notas: | Ph.D. Thesis.
Conteúdo: | High concentrations of phosphate in plants have been found to decrease vesicular-arbuscular (VA) mycorrhizal infection and its effect on plant growth, However, little is known about the effect of nitrogen on the VA mycorrhizal symbiosis, and this was examined in the present study. Mycorrhizal infection in onion was inhibited by nitrogen not only when N was added to soil, but also when were dipped into a solution containing N. Per cent N in the root tissues was increased in both cases. By contrast, infection and nitrogen concentrations in white clover were little a affected by added nitrogen. The level of nitrogen in the plant rather than in the soil was believed to be the major factor affecting infection. Similar results were obtained with other legume-non-legume combinations. In other tests with legumes, nodulation was stimulated by the VA fungus. The forms of nitrogen are important to mycorrhizal plants and their effects are influenced by soil phosphate levels. In experiments with onions growing in a soil in which they both N and P deficient, plants only responded to added nitrogen when phosphate was also applied. Non-mycorrhizal plants given phosphate grew well with both Ca(NO3)2.4H2O and NH4NO3. Mycorrhizal plants grew bigger with nitrogen added as Ca(NO3)2.4H2O than as NH4NO3; when a small amount of P was applied, mycorrhizal plants grew equally well with either form of N. It was inferred that mycorrhiza is inhibited more by ammonium-nitrogen than by nitrate-nitrogen. Shading decreased mycorrhizal infection, an effect that was more pronounced with ammonium-N ((NH4)2SO4) than with nitrate-N (Ca(NO3)2.4H2O). Onion roots contained less carbohydrate in the ammonium-N than in the nitrate-N treatment and the differences were greater in shaded plants. These results showed a direct relationship between root carbohydrate levels and early VA mycorrhizal infection in young onion seedlings, thereby supporting the "Carbohydrate theory" of Bjorkman for ectomycorrhiza.
Palavras-Chave: | Crescimento de planta; Efeito; Fungus; Growth; Inglaterra; Mycorrhiza; Phosphatos; Plant; VA; Vesicular-arbuscular.
Thesagro: | Carboidrato; Crescimento; Fosfato; Fungo; Micorriza; Nitrogênio; Planta; Simbiose.
Thesaurus Nal: | England; nitrogen; plant growth; symbiosis.

Categoria do assunto:

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X Pesquisa, Tecnologia e Engenharia

Registro original: | Embrapa Soja (CNPSO)

Exemplares:

CPATSA - (23849-1) - ADD - TS - PP - 15/1984 -  - 1984.00015 - DIS
CNPSO - (1182-1) - ADD - TS - PP - 14/84 -  - 14/84 - DIS