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Medientyp:
E-Artikel
Titel:
Comparison of Stages of Vesicular-Arbuscular Mycorrhiza Formation in Sudangrass Grown at Two Levels of Phosphorus Nutrition
Beteiligte:
Schwab, S. M.;
Menge, J. A.;
Leonard, R. T.
Erschienen:
American Botanical Society, 1983
Erschienen in:
American Journal of Botany, 70 (1983) 8, Seite 1225-1232
Sprache:
Englisch
ISSN:
0002-9122;
1537-2197
Entstehung:
Anmerkungen:
Beschreibung:
Several stages of the infection process by the vesicular-arbuscular mycorrhizal fungus, Glomus fasciculatus, were compared in roots of sudangrass (Sorghum vulgare) grow in phosphorus-deficient or phosphorus-amended soil. Germination of fungal spores in soil and morphology of the fungus within the root were not affected by phosphorus amendment. There were no significant differences between phosphorus treatments in the percent of root infected or total length of root infected by the fungus until 25 days after inoculation. Between 25 and 35 days after inoculation, the percent of root infected increased 5-fold, and the total length of infected root increased nearly 30-fold in the phosphorus-deficient plants. Neither percent nor total length of infected root increased significantly over the same time period in the phosphorus amended plants. The increase in mycorrhiza formation in the phosphorus-deficient plants was associated with an increase in the number of penetrations into the root by the fungus, but not with an increase in the size of individual infections. Proliferation of external hyphae was greater in phosphorus-deficient than phosphorus-amended plants 25 days after inoculation. These data suggest that phosphorus nutrition of the host does not affect prepenetration stages of mycorrhiza formation by G fasciculatus However, external hyphal growth following initial penetration of the host is reduced with phosphorus amendment. The subsequent ability of the fungus to form secondary penetrations is thus decreased, ultimately resulting in the overall decrease in mycorrhiza formation commonly observed in plants receiving high levels of phosphorus.