Pharmacological investigation of Citrus limon leaf extract and its efficacy as biofungicide against potato rot disease
- Authors: Ehiobu, John Meomikem
- Date: 2021
- Subjects: Potatoes -- Diseases and pests , Potato ring rot , Bacterial wilt of potato
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23666 , vital:58278
- Description: Potato, the fourth major staple and economic food crop is readily attacked by fungal pathogens. This is of public and economic importance. Interests have shifted from the age-old rot management by synthetic fungicide to botanicals due to the attended negative effects of the former. The bioactive molecules domicile in plants have been found to possess pharmacological properties against diverse pathogens of plants and animals. This study investigated the pharmacological properties of the Citrus limon leaf extracts of using different leaf solvent extracts and the potential utilization of these extracts in managing potato rot diseases. The tubers were purchased from selected supermarkets within Raymond Mhlaba Local Municipality of the Eastern Cape province of South Africa. A survey study was carried out by using a well-structured designed questionnaire administered to selected supermarkets in three major towns namely; Alice, King Williams Town and Fort Beaufort. The questionnaires were randomly administered to 62 supermarket owners in each of the selected super markets. Rotten potato tubers were randomly collected from these supermarkets. On each occasion, the tubers were packaged in a sterile polythene bag and taken to the laboratory for isolation and identification of the pathogens associated with the disease (rot) using standard mycological techniques. Fresh leaves of Citrus limon were collected from a residential area within the study location, processed and extracted using water, ethanol and acetone solvents before analysing their phytochemical contents, antioxidant properties and antifungal activites against the rotten potato tuber pathogens at graded concentrations of 25g/l, 50g/l and 100g/l. Effects of different temperatures (10-40oC) on the tuber weight loss and mycelia growth were also evaluated. Analysis of the results revealed that the supermarket owners incurred economic loss of 43percentwith annual potato loss incurement of R1501- 2000. The losses occurred more in the warmer summer seasons. About 91percent of the respondents agreed to use any novel botanicals, as alternatives to the increasing artificial fungicides due to their high costs, toxic nature and the environmental hazard effects. Phytochemical results showed that the ethanol extracts yielded the highest total flavonoid quantification of 1052.58±39.44mg GAE/g, followed by phenols (209.72 ± 6.38 GAE/g), alkaloid (12.23percent) and saponin (5.53percent). There was no significant difference in phenol content between the acetone and ethanol; but a significant difference (P < 0.05) was observed for the aqueous extracts of C. limon leaf. The aqueous, acetone and ethanol leaf extracts also showed significantly high antioxidant capacity with the ABTS (67.85percent - 90.85percent), FRAP (128.26 - 182.12 mgRE/g) and DPPH (28.72percent - 33.64percent). The fungal pathogens isolated from rotten potato tubers were identified as Curvularia mebaldsii, Fusarium oxysporum and Penicillium species. The effect of C. limon leaf extracts on the isolates was concentration and extracting solvent dependent. For the aqueous solvent, the mycelial growth of Penicillium species were most inhibited with 95.82 ± 0.11percent, 89.1 ± 0.19percent and 74.81 ± 0.82 percent, followed by F. oxysporum with 76 ± 2.83, 76percent ± 5.95percent and 29.05 ± 3.17percent and Curvularia mebaldsii (68.46 ± 3.0percent, 63.76 ± 2.87 percent and 53.47± 3.64percent) respectively. However, the ethanol and acetone extracts at 100g/l concentrations displayed a 100percent growth inhibition against the three rot fungi. The effects 50g/l ethanol concentration also showed 100percent against both F. oxysporum and C. mebaldsii, but 90.97percent against Penicillium sp. The growth inhibition at 25g/l extract against F. oxysporum were 99percent and 96.52percent for acetone and ethanol extracts respectively, but 96.52percent and 85.57percent against C. mebaldsii and Penicillium sp. respectively. The effects of temperature on the average radial mycelial growth of fungal isolates at 10oC, 20oC, 30oC, and 40oC were 17.53 mm, 28.33 mm, 42.33 mm, and 34.50 mm respectively. The highest percentage weight loss of infected potato was 19.53percent at 30oC, while the lowest was 5.12percent at 10oC. The optimal temperature of maximum activities of the isolates was 30oC and this indicates that healthy potato tubers stored at 30oC will undergo faster fungal deterioration and spoilage than those stored at 10oC. The findings indicated that the ethanol and acetone extracts displayed significantly higher phytochemicals, antioxidant properties and in vitro antifungal activity against the potato rot disease fungal pathogens. Hence, the plant leaf could be considered as a potent bio-fungicides against potato rot disease. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021
- Authors: Ehiobu, John Meomikem
- Date: 2021
- Subjects: Potatoes -- Diseases and pests , Potato ring rot , Bacterial wilt of potato
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23666 , vital:58278
- Description: Potato, the fourth major staple and economic food crop is readily attacked by fungal pathogens. This is of public and economic importance. Interests have shifted from the age-old rot management by synthetic fungicide to botanicals due to the attended negative effects of the former. The bioactive molecules domicile in plants have been found to possess pharmacological properties against diverse pathogens of plants and animals. This study investigated the pharmacological properties of the Citrus limon leaf extracts of using different leaf solvent extracts and the potential utilization of these extracts in managing potato rot diseases. The tubers were purchased from selected supermarkets within Raymond Mhlaba Local Municipality of the Eastern Cape province of South Africa. A survey study was carried out by using a well-structured designed questionnaire administered to selected supermarkets in three major towns namely; Alice, King Williams Town and Fort Beaufort. The questionnaires were randomly administered to 62 supermarket owners in each of the selected super markets. Rotten potato tubers were randomly collected from these supermarkets. On each occasion, the tubers were packaged in a sterile polythene bag and taken to the laboratory for isolation and identification of the pathogens associated with the disease (rot) using standard mycological techniques. Fresh leaves of Citrus limon were collected from a residential area within the study location, processed and extracted using water, ethanol and acetone solvents before analysing their phytochemical contents, antioxidant properties and antifungal activites against the rotten potato tuber pathogens at graded concentrations of 25g/l, 50g/l and 100g/l. Effects of different temperatures (10-40oC) on the tuber weight loss and mycelia growth were also evaluated. Analysis of the results revealed that the supermarket owners incurred economic loss of 43percentwith annual potato loss incurement of R1501- 2000. The losses occurred more in the warmer summer seasons. About 91percent of the respondents agreed to use any novel botanicals, as alternatives to the increasing artificial fungicides due to their high costs, toxic nature and the environmental hazard effects. Phytochemical results showed that the ethanol extracts yielded the highest total flavonoid quantification of 1052.58±39.44mg GAE/g, followed by phenols (209.72 ± 6.38 GAE/g), alkaloid (12.23percent) and saponin (5.53percent). There was no significant difference in phenol content between the acetone and ethanol; but a significant difference (P < 0.05) was observed for the aqueous extracts of C. limon leaf. The aqueous, acetone and ethanol leaf extracts also showed significantly high antioxidant capacity with the ABTS (67.85percent - 90.85percent), FRAP (128.26 - 182.12 mgRE/g) and DPPH (28.72percent - 33.64percent). The fungal pathogens isolated from rotten potato tubers were identified as Curvularia mebaldsii, Fusarium oxysporum and Penicillium species. The effect of C. limon leaf extracts on the isolates was concentration and extracting solvent dependent. For the aqueous solvent, the mycelial growth of Penicillium species were most inhibited with 95.82 ± 0.11percent, 89.1 ± 0.19percent and 74.81 ± 0.82 percent, followed by F. oxysporum with 76 ± 2.83, 76percent ± 5.95percent and 29.05 ± 3.17percent and Curvularia mebaldsii (68.46 ± 3.0percent, 63.76 ± 2.87 percent and 53.47± 3.64percent) respectively. However, the ethanol and acetone extracts at 100g/l concentrations displayed a 100percent growth inhibition against the three rot fungi. The effects 50g/l ethanol concentration also showed 100percent against both F. oxysporum and C. mebaldsii, but 90.97percent against Penicillium sp. The growth inhibition at 25g/l extract against F. oxysporum were 99percent and 96.52percent for acetone and ethanol extracts respectively, but 96.52percent and 85.57percent against C. mebaldsii and Penicillium sp. respectively. The effects of temperature on the average radial mycelial growth of fungal isolates at 10oC, 20oC, 30oC, and 40oC were 17.53 mm, 28.33 mm, 42.33 mm, and 34.50 mm respectively. The highest percentage weight loss of infected potato was 19.53percent at 30oC, while the lowest was 5.12percent at 10oC. The optimal temperature of maximum activities of the isolates was 30oC and this indicates that healthy potato tubers stored at 30oC will undergo faster fungal deterioration and spoilage than those stored at 10oC. The findings indicated that the ethanol and acetone extracts displayed significantly higher phytochemicals, antioxidant properties and in vitro antifungal activity against the potato rot disease fungal pathogens. Hence, the plant leaf could be considered as a potent bio-fungicides against potato rot disease. , Thesis (PhD) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Date Issued: 2021
The nature of violence in South African universities African universities: The politics of process
- Mutongoza, Bonginkosi Hardy https://orcid.org/0000-0002-2939-1274
- Authors: Mutongoza, Bonginkosi Hardy https://orcid.org/0000-0002-2939-1274
- Date: 2021
- Subjects: Education, Higher -- Political aspects , Universities and colleges -- South Africa , Campus violence
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27909 , vital:70816
- Description: The high levels of violence that plague South Africa’s universities are symptomatic of an education system that is under attack, with institutions of higher learning not reflecting the peacefulness and safety which are oftentimes associated with the pursuit of learning. While violence in societies and educational institutions globally continues to intensify in viciousness and frequency, this is especially worrisome for South Africa, a country regarded as one of the most violent in the world. South African education institutions are admittedly extremely violent, yet there are relatively few mechanisms to enable the verification of trends in violence, or to cross-reference and compare incidents, thus making the reduction of violence problematic. The contention is that the general outlook of violence at educational institutions appears to echo the relentless violence which haunts South African communities in general. Against this background, the current study sought to explore the nature of violence in South African universities. To achieve this, the study was guided by an exploration of student and staff experiences of violence in universities, the causes of violence in such sites, and the recording thereof. Underpinned by a pragmatist paradigm, this study utilised a mixed-methods approach to ‘get under the skin’ of the problem of violence in universities. Within the mixed-methods approach, the study employed a single-phase convergent design, which enabled the researcher to reach comprehensive conclusions on violence in universities, by merging and comparing qualitative and quantitative datasets. In the quantitative phase of the study, a simple random sampling technique was used to select a total of 1 776 students and 250 staff, while 32 students and four staff were conveniently sampled during the qualitative phase. The data for this study were collected using an online survey in the quantitative phase, and semi-structured interviews and document reviews in the qualitative phase. The findings of this investigation revealed that violence happened in six main configurations, namely student-on-student violence, staff-on-student violence, staff-on-staff violence, student-on-staff violence, self-directed violence, and protest-related violence. In addition, the findings revealed diverse causes of violence in universities, chief of which were alcohol and drug abuse, poor security, the abuse of power or authority, impunity, and psychosocial factors, among others. Factors that impeded the recording of violence in universities included the normalisation of violence, a lack of consequences for the perpetrators, a lack of procedural awareness, cronyism and brotherhoods, and a lack of protection from reprisal for reporting perpetrators. The production of violence in South African universities was also found to be significantly shaped by wider structures that included sexuality, gender, age, socioeconomic status, and race and ethnicity. These structures were found to be prominent in increasing the likelihood of violence being perpetrated. Based on the reported findings, the study moved to recommend that, in order to reduce experiences of violence in South African universities, institutions adopt multidimensional approaches to combatting this scourge. The fact that violence was noted to occur in multiple configurations, means multiple viewpoints are required to reduce and ultimately combat it. This calls for a multi-stakeholder approach that transcends a reliance on the traditional university policymakers, and a concerted consultative process to formulate and renew policies that can help to address university violence. The study further recommended that reporting structures be decentralised at universities, in a bid to improve the smoothness of related processes. In this respect, it will be essential for universities to consider setting up anonymous reporting platforms online, to move with the times and ensure more urgent responses, as opposed to a continued reliance on present systems that are replete with red tape. Additionally, universities may consider outsourcing divisions that deal with violence reporting, to minimise conflicts of interest when dealing with such cases. The researcher concluded that violence in universities threatens the very purpose of tertiary education – members of the university community must be able to freely pursue their aspirations in peaceful environments. As such, for as long as campuses experience violence in any of its varied forms, a proverbial dark cloud will forever frustrate the quest for quality and transformative education that has the potential to reverse-engineer inequality, poverty, and underdevelopment in South Africa, as contemplated in various development plans. , Thesis (PhD) -- Faculty of Education, 2021
- Full Text:
- Date Issued: 2021
- Authors: Mutongoza, Bonginkosi Hardy https://orcid.org/0000-0002-2939-1274
- Date: 2021
- Subjects: Education, Higher -- Political aspects , Universities and colleges -- South Africa , Campus violence
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/27909 , vital:70816
- Description: The high levels of violence that plague South Africa’s universities are symptomatic of an education system that is under attack, with institutions of higher learning not reflecting the peacefulness and safety which are oftentimes associated with the pursuit of learning. While violence in societies and educational institutions globally continues to intensify in viciousness and frequency, this is especially worrisome for South Africa, a country regarded as one of the most violent in the world. South African education institutions are admittedly extremely violent, yet there are relatively few mechanisms to enable the verification of trends in violence, or to cross-reference and compare incidents, thus making the reduction of violence problematic. The contention is that the general outlook of violence at educational institutions appears to echo the relentless violence which haunts South African communities in general. Against this background, the current study sought to explore the nature of violence in South African universities. To achieve this, the study was guided by an exploration of student and staff experiences of violence in universities, the causes of violence in such sites, and the recording thereof. Underpinned by a pragmatist paradigm, this study utilised a mixed-methods approach to ‘get under the skin’ of the problem of violence in universities. Within the mixed-methods approach, the study employed a single-phase convergent design, which enabled the researcher to reach comprehensive conclusions on violence in universities, by merging and comparing qualitative and quantitative datasets. In the quantitative phase of the study, a simple random sampling technique was used to select a total of 1 776 students and 250 staff, while 32 students and four staff were conveniently sampled during the qualitative phase. The data for this study were collected using an online survey in the quantitative phase, and semi-structured interviews and document reviews in the qualitative phase. The findings of this investigation revealed that violence happened in six main configurations, namely student-on-student violence, staff-on-student violence, staff-on-staff violence, student-on-staff violence, self-directed violence, and protest-related violence. In addition, the findings revealed diverse causes of violence in universities, chief of which were alcohol and drug abuse, poor security, the abuse of power or authority, impunity, and psychosocial factors, among others. Factors that impeded the recording of violence in universities included the normalisation of violence, a lack of consequences for the perpetrators, a lack of procedural awareness, cronyism and brotherhoods, and a lack of protection from reprisal for reporting perpetrators. The production of violence in South African universities was also found to be significantly shaped by wider structures that included sexuality, gender, age, socioeconomic status, and race and ethnicity. These structures were found to be prominent in increasing the likelihood of violence being perpetrated. Based on the reported findings, the study moved to recommend that, in order to reduce experiences of violence in South African universities, institutions adopt multidimensional approaches to combatting this scourge. The fact that violence was noted to occur in multiple configurations, means multiple viewpoints are required to reduce and ultimately combat it. This calls for a multi-stakeholder approach that transcends a reliance on the traditional university policymakers, and a concerted consultative process to formulate and renew policies that can help to address university violence. The study further recommended that reporting structures be decentralised at universities, in a bid to improve the smoothness of related processes. In this respect, it will be essential for universities to consider setting up anonymous reporting platforms online, to move with the times and ensure more urgent responses, as opposed to a continued reliance on present systems that are replete with red tape. Additionally, universities may consider outsourcing divisions that deal with violence reporting, to minimise conflicts of interest when dealing with such cases. The researcher concluded that violence in universities threatens the very purpose of tertiary education – members of the university community must be able to freely pursue their aspirations in peaceful environments. As such, for as long as campuses experience violence in any of its varied forms, a proverbial dark cloud will forever frustrate the quest for quality and transformative education that has the potential to reverse-engineer inequality, poverty, and underdevelopment in South Africa, as contemplated in various development plans. , Thesis (PhD) -- Faculty of Education, 2021
- Full Text:
- Date Issued: 2021
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