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Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa
Dissertation (MSc)--University of Pretoria, 2015.
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| Format: | Thesis |
| Language: | English |
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2026
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| _version_ | 1867613712145186816 |
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| access_status_str | Open Access |
| author2 | Labuschagne, Nico |
| author_browse | Labuschagne, Nico |
| author_facet | Labuschagne, Nico |
| collection | Thesis |
| description | Dissertation (MSc)--University of Pretoria, 2015. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/110166 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:30.132Z |
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| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/110166 Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa Labuschagne, Nico gerhardusbreedt@gmail.com Coutinho, Teresa A. Breedt, Gerhardus Field Maize Yield Biofertilizer Rhizobacteria Dissertation (MSc)--University of Pretoria, 2015. Zea mays L. commonly known as “maize” is a grain crop within the family of Poaceae (Paliwal, 2000). According to Miracle (1965), maize was introduced to South Africa (R.S.A.) by the Portuguese in the 17th century from South America. Since the introduction, maize production has developed into one of the largest agricultural branches in South Africa and rated as the most important grain crop in R.S.A. (Du Plessis, 2003). According to the FAO (2014) South African maize yield per hectare has decreased from an average of 4.81tha-1 in 2011 to 4.19tha-1 in 2013. On the other hand the areas planted in the Western and Central regions of Africa have increased significantly from 3.2 million hectares to 8.9 million hectares since 1961 to 2005. This devotion of land to maize production increased the total yield per country but the average yield is still 1.3tha-1 compared to the production potential of 8.6tha-1 (FAO, 2004). Various environmental, cultural and nutritional factors e.g. adapted cultivars, plant population, crop management, fertilisation, weed, disease and insect control etc. could explain the low yields observed in these maize producing areas (ARC, 2008). These limiting factors are dependent on each other and as the human population increases, more pressure is being put on the soil to increase production which results in the slow exhaustion of soil fertility (Shepard & Soule, 1998). The discovery of mineral fertilizers led to the replacement of biological fertilizers. According to Oikarinen (1996) these mineral fertilizers are inefficient, negatively affect the environment and lower the product quality. The slow exhaustion of soil fertility and the negative impact mineral fertilisers have on the environment has created the need to study biosystems in order to promote sound farming practices. The advances in modern science created a niche to better understand biosystems and the impact chemical fertilisers have on these systems. In turn the better the understanding of the negative impacts on these biosystems the better it will promote the environmentally friendly biological fertiliser concept. The term rhizosphere refers to the soil around the root system that the plant influences biologically through secreting various substances into this soil xi compartment. Rhizobacteria are bacteria classified as living in the rhizosphere soil compartment and if beneficial to the plant, the rhizobacteria are termed Plant Growth Promoting Rhizobacteria (PGPR). Various studies have been conducted to utilise the PGPR-plant interaction to promote plant growth and thereby increase farming efficiency and improve food security. The current study evaluated selected PGPR isolates from the University of Pretoria’s culture collection for their efficacy as growth enhancing agents in maize. The selected PGPR isolates were first screened for their growth promoting capabilities under greenhouse conditions. From these screening trials the best isolates were identified and re-evaluated in the greenhouse at various dosages, nutrient levels and different formulations to ensure optimal performance before testing under field conditions. After the greenhouse trials the best performing isolates were extensively evaluated for three seasons from 2010 to 2013 in field trials conducted in the South Western area of the Limpopo Province, South Africa. During the first season remarkable effects were obtained with the seed inoculated isolates S1 and S2-08 resulting in a 1.12tha-1 grain increase over that of the control. However, these strains were identified as Bacillus cereus and they could be potential human pathogens. These strains tested positive for the human diahoreal toxin and were subsequently excluded from the study and replaced with other PGPR strains that showed potential as plant growth stimulants in various other research trials at the University of Pretoria. During the successive years the overall best performing rhizobacterial strain in all soil types was T-19, identified as Lysinibacillus sphearicus. From this study it was evident that different soil types had a profound effect on the ability of the rhizobacteria to promote plant growth. In the field trials it was observed that the higher the clay content the lower the PGPR stimulatory effect on the plant and vice versa. In the laboratory, isolate T-19 tested positive for indole-3-acetic acid (IAA) production and limited nitrogen fixation, while the commercial product Brus® tested positive for xii all the modes of action that were evaluated. This then raised the question as to why the Lysinibacillus sphearicus strain (T19) with its limited mode of action consistently outperformed inoculants with a broader spectrum of action when evaluated under field conditions. In the current study PGPR strains were identified that had demonstrated plant growth enhancement capabilities, not only under greenhouse conditions, but also under field conditions. These strains appear to have commercial potential as biofertilisers. This is becoming increasingly important in the context of the global emphasis on more environmentally friendly agricultural practices. By demonstrating significant increases of maize yield in the field after seed treatment with selected PGPR strains, the current study provided additional evidence for the potential of PGPR application in the context of a more sustainable agricultural system. Microbiology and Plant Pathology MSc 2026-05-15T17:26:32Z 2026-05-15T17:26:32Z 15/07/09 2015 Dissertation http://hdl.handle.net/2263/110166 en application/pdf |
| spellingShingle | Field Maize Yield Biofertilizer Rhizobacteria Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa |
| title | Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa |
| title_full | Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa |
| title_fullStr | Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa |
| title_full_unstemmed | Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa |
| title_short | Efficacy of selected rhizobacteria for growth promotion of maize and suppression of Fusarium root and crown rot in South Africa |
| title_sort | efficacy of selected rhizobacteria for growth promotion of maize and suppression of fusarium root and crown rot in south africa |
| topic | Field Maize Yield Biofertilizer Rhizobacteria |
| url | http://hdl.handle.net/2263/110166 |