Browsing by Author "Rossouw, Marthinus Jacob"

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    Application of plant growth promoting substances and arbuscular mycorrhizal fungi for phytostabilisation of mine tailings
    (Stellenbosch : Stellenbosch University, 2016-03) Rossouw, Marthinus Jacob; Hills, Paul N.; Thompson, David I.; Stellenbosch University. Faculty of Agrisciences. Dept. of Genetics. Institute for Plant Biotechnology (IPB).
    ENGLISH ABSTRACT: This study focused on investigating methods of phytostabilisation of mine tailings operated by Palabora Copper in South Africa. Capping material and mine tailing at various sites of the mine were collected and used in pot trials to investigate the effect of a number of plant growth promoting substances (PGPS) on several of grass species currently used in effort to stabilise the areas in question. Lumichrome, strigolactones (GR24), flavonoids (CropbioLife™), smoke-water (karrikins) and arbuscular mycorrhizal fungi (Mycoroot™) were used as PGPS to investigate growth-promoting effects on i) Anthephora pubescens, Cenchrus ciliaris, Chloris gayana, Cynodon dactylon, and Panicum maximum which are species currently used by Palabora Copper for rehabilitation of mine tailings, and ii) Additional grass species theoretically suited to surviving the environment. Treatments were applied on 2-week old transplanted grass seedlings in pot trials containing mine capping material as the substrate, to infer treatment responses. Trypan-Blue staining procedures were used to ascertain which grass species formed symbiotic relationship with arbuscular mycorrhizal fungi (AMF), which would potentially aid in their survival in deleterious areas. Germination rates were measured to determine the fastest germinating species of the selected grasses with Eragrostis teff and Melinis repens germinating the quickest in the mine capping material. Capping material and mine tailing samples were collected at sites under revegetation by Palabora Copper. This included samples of the rhizosphere of locally abundant plants at two sites: a recently (two years) capped mine tailing, and a rock dump site (capped 10-12 years previously). Five rhizosphere samples were collected from individuals of Cenchrus ciliaris, Enneapogon cenchroides, and Tephorisia polystachya (a locally abundant forb species) at site 1 and Cenchrus ciliaris, Stipagrostis hirtigluma, Tephrosia polystachya, and Pennisetum setaceum at site 2. At both sites the soil of open areas devoid of plants was also sampled. Metagenomic DNA was extracted from the collected samples, often following enrichment techniques. Dilution series spread plates to determine culturable bacteria present in the tailing samples were also utilised. Polymerase Chain Reactions were implemented to produce amplicons of conserved regions within AMF and bacteria present in the mine tailing site. The predominant genera of bacteria detected in the collected tailing samples belonged to Bacillus. However, due to the use of enrichment techniques it was not possible to comment on the relative abundance of different bacteria in the environment where the samples were collected. Due to the small-scale ex situ nature of the experiments the results gained from the PGPS treatment trials and microbial DNA isolation are not necessarily representative of the ecological environment present in situ. However, PGPS treatment of the selected grasses did not elicit any clear beneficial responses in the measured growth parameters, making application thereof of limited benefit for phytostabilisation purposes. Trypan staining revealed most of the grass species are capable of forming symbiotic relationships with mycorrhizal fungi, with trials indicating that AMF might benefit plants present in the mine tailings.