Investigating the use of Arbuscular Mycorrhizas and Plant Growth Promoting Bacteria to improve the drought tolerance of maize (Zea mays L.)
- Authors: Moore, Nicolle Maureen
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54587 , vital:26591
- Description: Maize (Zea mays L.) is a direct staple food crop in Africa and remains an essential component of global food security, with maize crops accounting for over 60% of the total harvested area of annual food crops. Stress caused by drought and high soil salinity limits crop growth and productivity more than any other single environmental factor, with grain yield reductions up to 76% depending on the severity of the drought and the plant growth stage. Arbuscular mycorrhizal (AM) fungi and Plant Growth Promotion Rhizobacteria (PGPR) have previously been shown to improve tolerance of plants to drought stress through a number of chemical and physiological processes. The aim of this investigation was to determine whether mycorrhizal fungi and rhizobacteria adapted to drought and saline conditions and possessing plant growth promoting (PGP) traits were able to stimulate plant growth responses when applied to Zea mays seeds growing under greenhouse conditions Bacterial isolates selected were tolerant to concentrations of NaCl up to 600 mM and maintained 50% growth at low water potentials (-1.44 MPa). They were positive for Indole Acetic Acid (IAA) production, phosphate solubilisation and secretion of siderophores. Bacterial isolates showing plant growth promoting potential were identified using 16S rDNA gene sequencing as Achromobacter xylosoxidans strains A8 and C54 and Klebsiella oxytoca strain M1. Mixed inoculum was prepared from indigenous communities of mycorrhizas in soils sampled from the Cerebos Salt Pan and the Kalahari Desert. Mycorrhizal diversity was investigated using 454-Pyrosequencing which revealed that the community composition was dominated by species in the Ambispora, Glomus and Paraglomus genera with a rare component represented by species in the Redeckera, Archaeospora and Geosiphon genera. Microscopic examination of plant roots at the end of the trial revealed the presence of diagnostic mycorrhizal structures within the root cells, confirming that colonization was successful. Plant growth response to microbial inoculation was assessed by monitoring changes in plant photosynthetic capacity over the duration of a 7 week pot trial. A significant difference in photosynthetic and biomass data was observed between drought and well-watered groups but no mycorrhizal or bacterial treatment effect was evident within the groups, despite the high levels of colonization by mycorrhizas. These results suggest that the beneficial effects of mycorrhizal colonization may be primarily attributed to improved nutrient and mineral uptake in conditions where nutrients are limiting, resulting in improved growth. The improved growth may then have secondary effects on the plant‟s ability to withstand drought. Having controlled for nutrient deficiency, it was not evident in this study that mycorrhizal fungi were able to stimulate a change in plant physiology and confer drought tolerance under the conditions imposed.
- Full Text:
- Date Issued: 2016
- Authors: Moore, Nicolle Maureen
- Date: 2016
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/54587 , vital:26591
- Description: Maize (Zea mays L.) is a direct staple food crop in Africa and remains an essential component of global food security, with maize crops accounting for over 60% of the total harvested area of annual food crops. Stress caused by drought and high soil salinity limits crop growth and productivity more than any other single environmental factor, with grain yield reductions up to 76% depending on the severity of the drought and the plant growth stage. Arbuscular mycorrhizal (AM) fungi and Plant Growth Promotion Rhizobacteria (PGPR) have previously been shown to improve tolerance of plants to drought stress through a number of chemical and physiological processes. The aim of this investigation was to determine whether mycorrhizal fungi and rhizobacteria adapted to drought and saline conditions and possessing plant growth promoting (PGP) traits were able to stimulate plant growth responses when applied to Zea mays seeds growing under greenhouse conditions Bacterial isolates selected were tolerant to concentrations of NaCl up to 600 mM and maintained 50% growth at low water potentials (-1.44 MPa). They were positive for Indole Acetic Acid (IAA) production, phosphate solubilisation and secretion of siderophores. Bacterial isolates showing plant growth promoting potential were identified using 16S rDNA gene sequencing as Achromobacter xylosoxidans strains A8 and C54 and Klebsiella oxytoca strain M1. Mixed inoculum was prepared from indigenous communities of mycorrhizas in soils sampled from the Cerebos Salt Pan and the Kalahari Desert. Mycorrhizal diversity was investigated using 454-Pyrosequencing which revealed that the community composition was dominated by species in the Ambispora, Glomus and Paraglomus genera with a rare component represented by species in the Redeckera, Archaeospora and Geosiphon genera. Microscopic examination of plant roots at the end of the trial revealed the presence of diagnostic mycorrhizal structures within the root cells, confirming that colonization was successful. Plant growth response to microbial inoculation was assessed by monitoring changes in plant photosynthetic capacity over the duration of a 7 week pot trial. A significant difference in photosynthetic and biomass data was observed between drought and well-watered groups but no mycorrhizal or bacterial treatment effect was evident within the groups, despite the high levels of colonization by mycorrhizas. These results suggest that the beneficial effects of mycorrhizal colonization may be primarily attributed to improved nutrient and mineral uptake in conditions where nutrients are limiting, resulting in improved growth. The improved growth may then have secondary effects on the plant‟s ability to withstand drought. Having controlled for nutrient deficiency, it was not evident in this study that mycorrhizal fungi were able to stimulate a change in plant physiology and confer drought tolerance under the conditions imposed.
- Full Text:
- Date Issued: 2016
Learners' views regarding their effective participation in school governance
- Authors: Munikwa, Julius
- Date: 2016
- Subjects: Student participation in administration
- Language: English
- Type: Thesis , Masters , Education
- Identifier: http://hdl.handle.net/10353/16013 , vital:40582
- Description: Effective learner participation for the development of Representative Council of Learners (RCL) governors in school governance (SG) is of great essence. A qualitative study was conducted in order to assess the learners’ views regarding their lived views and experiences in SG. Twenty four (24) RCL and class representatives from three data sites comprising three high schools in East Cape, in the East London District Education participated in the study. Data was gathered through semi-structured interviews, focus group discussions and document analysis from two convenient and one snowball samples, respectively. From each school, a chairperson, a secretary and six focus group discussions (FDGs) members were utilised as participants in order to enrich the study. In doing so, the study made use of Wilcox’s ladder of participation as the lens to unpack the learners’ views regarding their effective participation in school governance. This ladder includes information, consultation, deciding together, acting together and supporting independent community interests. The findings showed that learner participation in both township and former Model C schools is significant. However, a number of pertinent factors that make the voices of learner governors to be stifled emerged. These include lack of capacity building, exclusion from other meetings, dominance of adult governors, lack of collaboration and the fact that learners have to be seen as being respectful and disciplined when in meetings with parents. This makes them to accept their role as a tool for middlemen between the parents, teachers and fellow students. These make the field of effective learner participation uneven, hence making them window dressers and have pseudo contributions in SG. The study therefore suggested that learners should be capacitated to make effective and meaningful contribution in school governance. Learners should work collaboratively with adult governors to enhance effective participation in SG.
- Full Text:
- Date Issued: 2016
- Authors: Munikwa, Julius
- Date: 2016
- Subjects: Student participation in administration
- Language: English
- Type: Thesis , Masters , Education
- Identifier: http://hdl.handle.net/10353/16013 , vital:40582
- Description: Effective learner participation for the development of Representative Council of Learners (RCL) governors in school governance (SG) is of great essence. A qualitative study was conducted in order to assess the learners’ views regarding their lived views and experiences in SG. Twenty four (24) RCL and class representatives from three data sites comprising three high schools in East Cape, in the East London District Education participated in the study. Data was gathered through semi-structured interviews, focus group discussions and document analysis from two convenient and one snowball samples, respectively. From each school, a chairperson, a secretary and six focus group discussions (FDGs) members were utilised as participants in order to enrich the study. In doing so, the study made use of Wilcox’s ladder of participation as the lens to unpack the learners’ views regarding their effective participation in school governance. This ladder includes information, consultation, deciding together, acting together and supporting independent community interests. The findings showed that learner participation in both township and former Model C schools is significant. However, a number of pertinent factors that make the voices of learner governors to be stifled emerged. These include lack of capacity building, exclusion from other meetings, dominance of adult governors, lack of collaboration and the fact that learners have to be seen as being respectful and disciplined when in meetings with parents. This makes them to accept their role as a tool for middlemen between the parents, teachers and fellow students. These make the field of effective learner participation uneven, hence making them window dressers and have pseudo contributions in SG. The study therefore suggested that learners should be capacitated to make effective and meaningful contribution in school governance. Learners should work collaboratively with adult governors to enhance effective participation in SG.
- Full Text:
- Date Issued: 2016
Observational cosmology with imperfect data
- Authors: Bester, Hertzog Landman
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/463 , vital:19961
- Description: We develop a formalism suitable to infer the background geometry of a general spherically symmetric dust universe directly from data on the past lightcone. This direct observational approach makes minimal assumptions about inaccessible parts of the Universe. The non-parametric and Bayesian framework we propose provides a very direct way to test one of the most fundamental underlying assumptions of concordance cosmology viz. the Copernican principle. We present the Copernicus algorithm for this purpose. By applying the algorithm to currently available data, we demonstrate that it is not yet possible to confirm or refute the validity of the Copernican principle within the proposed framework. This is followed by an investigation which aims to determine which future data will best be able to test the Copernican principle. Our results on simulated data suggest that, besides the need to improve the current data, it will be important to identify additional model independent observables for this purpose. The main difficulty with current data is their inability to constrain the value of the cosmological constant. We show how redshift drift data could be used to infer its value with minimal assumptions about the nature of the early Universe. We also discuss some alternative applications of the algorithm.
- Full Text:
- Date Issued: 2016
- Authors: Bester, Hertzog Landman
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/463 , vital:19961
- Description: We develop a formalism suitable to infer the background geometry of a general spherically symmetric dust universe directly from data on the past lightcone. This direct observational approach makes minimal assumptions about inaccessible parts of the Universe. The non-parametric and Bayesian framework we propose provides a very direct way to test one of the most fundamental underlying assumptions of concordance cosmology viz. the Copernican principle. We present the Copernicus algorithm for this purpose. By applying the algorithm to currently available data, we demonstrate that it is not yet possible to confirm or refute the validity of the Copernican principle within the proposed framework. This is followed by an investigation which aims to determine which future data will best be able to test the Copernican principle. Our results on simulated data suggest that, besides the need to improve the current data, it will be important to identify additional model independent observables for this purpose. The main difficulty with current data is their inability to constrain the value of the cosmological constant. We show how redshift drift data could be used to infer its value with minimal assumptions about the nature of the early Universe. We also discuss some alternative applications of the algorithm.
- Full Text:
- Date Issued: 2016
The design of a primary healthcare centre for women and children in KwaZakhele, Port Elizabeth
- Authors: Du Preez, Ashleigh
- Date: 2016
- Subjects: Health facilities -- Designs and plans Health facilities -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MArch
- Identifier: http://hdl.handle.net/10948/38863 , vital:35008
- Description: This treatise focuses on the design of a primary health care centre for women and children in Kwazakhele, Port Elizabeth. The primary health care facility will provide the space ‘in-between’ home and hospital and will promote improved maternal care by concentrating on antenatal and postnatal services, delivered in a safe environment. The Centre will encompass an understanding of cultural, social and economic informants of health and enable an empowerment of community through a holistic approach to health care design. The Centre aims at dealing with both physical and mental issues that are connected to pregnancy, as well as other aspects of women’s health needs. A maternity ward, as well as a psychological component that deals with antenatal depression and rape counselling, will be incorporated into the design. Understanding traditions in township architecture and the design of healthcare centres internationally and in South Africa provide the basis of a cultural engagement stimulating the design of a health centre providing opportunities for social interaction.By enhancing the urban space, a better quality of living will be provided in the community. Through this intervention, the promotion of wellness will be stimulated and strengthened.
- Full Text:
- Date Issued: 2016
- Authors: Du Preez, Ashleigh
- Date: 2016
- Subjects: Health facilities -- Designs and plans Health facilities -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Masters , MArch
- Identifier: http://hdl.handle.net/10948/38863 , vital:35008
- Description: This treatise focuses on the design of a primary health care centre for women and children in Kwazakhele, Port Elizabeth. The primary health care facility will provide the space ‘in-between’ home and hospital and will promote improved maternal care by concentrating on antenatal and postnatal services, delivered in a safe environment. The Centre will encompass an understanding of cultural, social and economic informants of health and enable an empowerment of community through a holistic approach to health care design. The Centre aims at dealing with both physical and mental issues that are connected to pregnancy, as well as other aspects of women’s health needs. A maternity ward, as well as a psychological component that deals with antenatal depression and rape counselling, will be incorporated into the design. Understanding traditions in township architecture and the design of healthcare centres internationally and in South Africa provide the basis of a cultural engagement stimulating the design of a health centre providing opportunities for social interaction.By enhancing the urban space, a better quality of living will be provided in the community. Through this intervention, the promotion of wellness will be stimulated and strengthened.
- Full Text:
- Date Issued: 2016
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