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Accueil du site → Master → Afrique du Sud → 1997 → The effect of vesicular-arbuscular mycorrhiza on the growth of two indigenous grass species Themeda triandra and Trachypogon spicatus grown on coalmine spoil topsoil.

University of KwaZulu-Natal (1997)

The effect of vesicular-arbuscular mycorrhiza on the growth of two indigenous grass species Themeda triandra and Trachypogon spicatus grown on coalmine spoil topsoil.

Lee, Alan

Titre : The effect of vesicular-arbuscular mycorrhiza on the growth of two indigenous grass species Themeda triandra and Trachypogon spicatus grown on coalmine spoil topsoil.

Auteur : Lee, Alan

Université de soutenance : University of KwaZulu-Natal

Grade : Master of Science 1997

Résumé partiel
The main project was an assessment of the effect that colonization by five different Vesicular-arbuscular mycorrhiza (VAM) cultures have on the growth of the indigenous-grasses Themeda triandra and Trachypogon spicatus, when grown on coalmine topsoil. With unamended topsoil, VAM showed the ability to significantly increase the growth of the grasses compared to non-VAM control plants. The amount of effect varied with the VAM inoculum culture type, with a VAM culture originally from the Cape Flats being the most effective. In a second trial, soil fertilized with nitrogen, potassium and low concentrations of phosphate (P) was used. Again VAM displayed the ability to improve grass plant growth. The increase in P caused the Large spore inoculum to become the most effective. This indicated that different VAM cultures are inhibited to different degrees by an increase in phosphate fertilization. The low level of VAM infection, in both trials, seemed to preclude most of the VAM associated nutrient uptake control. Varying reports have been published on the effect of fertilization on VAM infection and colonization. In an attempt to further elucidate the role of fertilizer in VAM inhibition, rhizosphere soil from a long term fertility trial near Witbank, S.A. was sampled. Amcoal environmental services fertilized forty-two plots with varying concentrations of nitrogen, potassium, phosphate and lime to assess the growth of a variety of grasses. The trial had been maintained for ten years before sampling was completed for this project. Samples from each plot were taken from the rhizosphere soil of the most prominent grass (Digitaria eriantha). VAM spores were extracted from all the samples and five different types of spores were identified and counted for each sample. By comparing spore counts from each plot, the effect that the fertilizer regime had on the VAM on that plot could be assessed. Variation in the concentrations of nitrogen (N) and potassium had no significant effect on VAM colonization. Very low concentrations of N could not be assessed as all plots had been initially top dressed with nitrogen fertilizer. Phosphate (P) fertilizer concentration had a marked effect on spore concentrations.

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