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The fungus Macrophomina phaseolina is the causal agent of several diseases of mungbean (Vigna radiata). One of these diseases, known as charcoal rot, causes spoilage of germinating seed lots, and occurs when seed contaminated with M. phaseolina is used for sprouting. The detection of the pathogen during seed testing prior to export leads to downgrading of the seed and a resultant financial penalty to the grain grower. The aims of this research were: to determine the location of M. phaseolina in diseased and symptomless tissue of mungbean plants; to determine the mode, site and timing of seed colonisation of mungbean; to determine the impact of biotic and abiotic factors on seed colonisation; to conduct an assessment of genotypic variation of M. phaseolina within single plants; to determine modes of transport of inoculum that contribute to foliage infection and seed colonisation of mungbean; and to assess both pre- and post-harvest management strategies in order to reduce or prevent seed colonisation, or to minimise the process of seed transmission. The location of M. phaseolina in mungbean plants was determined through serial sectioning of, and subsequent isolation from, naturally infected host tissue. A large proportion of the mungbean tissue infected by M. phaseolina was found to be symptomless. Moreover, there were large areas of ostensibly pathogen-free tissue separating infection foci, thus indicating a strong likelihood of independent aerial infections. A selection of 14 isolates obtained from serial sectioning were assessed for genotypic variation with six primers using RAPD analysis. Of the 36 bands that were scored, 78% were polymorphic and as a result, 12 distinct genotypes were detected. Polymorphisms were also detected amongst isolates obtained from the same discrete infection area on single plants, which strongly suggests the occurrence of multiple aerial infections. Various methods of controlled inoculation including soil infestation, pod and foliar inoculations, and artificial seed infestation, were used to determine how mungbean seeds are colonised by M. phaseolina. Additionally, most of these inoculation methods were coupled with a series of abiotic treatments (temperature regimes, watering regimes, application of herbicides) that were designed to initiate stress conditions within infected plants, and possibly trigger growth of M. phaseolina from the infection courts and colonise seed. Seed colonisation was established in vitro and in vivo when immature pods were directly inoculated with microsclerotia of M. phaseolina. At least two days exposure at 100% relative humidity (RH) was necessary to establish seed infection in detached mungbean pods that were inoculated with microsclerotia of M. phaseolina. Extensive seed infection was still obtained when one or more days of 100% RH was interrupted by up to three days at low humidity. All except one of the other methods of controlled inoculation failed to produce colonised seed even when combinations of stresses were applied. Only when the bipyridylium herbicide ‘Spray Seed 250’ was applied to plants following the inoculation of mungbean stems within 13 cm of the pods, was seed colonised by M. phaseolina. This result raises the possibility that delayed harvesting of desiccated mungbean crops may promote further colonisation of mungbean tissue, including seed. Very strong evidence for the colonisation of mungbean seeds after deposition of soil-splashed inoculum of M. phaseolina onto pods was obtained through field and laboratory-based studies. Soil-splashed inoculum (most likely microsclerotia) was also found to be the source of inoculum responsible for the development of Macrophomina leaf blight of mungbean at several regional sites. To further investigate this finding, areas of several mungbean crops growing in naturally infested soil were covered in hessian cloth to prevent soil-splash and assessments of the levels of seed colonisation between covered and uncovered areas were made. Although colonisation of seed in the covered areas was significantly lower than in the uncovered areas, covering the soil did not eliminate colonisation of seed. This result suggests that inoculum dispersal, leading to pod infection and subsequent seed colonisation, occurs not only in splashed-soil but also by other means. Soil transported to the extra-floral nectaries of mungbeans by ants was found to contain infective inoculum of M. phaseolina. Furthermore, air-borne debris and dust collected in a trap contained viable microsclerotia of the pathogen. Isolates of M. phaseolina collected from both sources were pathogenic on mungbean seedlings, and suspensions of ant-transported soil and air-borne dust/debris infected mungbean pods and seed. This is the first report of both modes of inoculum dispersal. All three modes undoubtedly contribute to the total level of colonised seed, but their relative importance remains to be determined. Several options for the management of charcoal rot in mungbean seeds were investigated. Application of the fungicide carbendazim to mungbean plants after flowering significantly decreased, but did not prevent, colonisation of mungbean seed by M. phaseolina. Consequently, this method of management holds little promise for mungbean growers. A large number of weeds common in Australian mungbean fields were newly reported as hosts of M. phaseolina. Isolates obtained from the infected, but symptomless weeds were pathogenic on mungbean seedlings, thus indicating a lack of host-specificity toward mungbean. It is strongly suspected that the use of herbicides to control weeds in reduced and zero-tillage farming systems is increasing the risk of infection in subsequent mungbean crops through the build-up of inoculum in soil. This increased risk of infection may be further exacerbated by retaining stubble infested with M. phaseolina on the soil surface, thereby increasing the amount of inoculum that could be splashed onto plant organs. Surface sterilisation, using sodium hypochlorite, significantly reduced colonisation levels in heavily colonised mungbean seed lines, but the process was not enhanced when a partial-vacuum was introduced to the process. In some seed lots, up to 32% of the seed was colonised only on the seed coat (defined here as contamination), whereas the remainder was internally infected. Surface sterilisation also reduced the overall colonisation of 132 commercial lines by approximately one-third. Storage of seed for one month at either 4°C or 15°C significantly reduced colonisation levels in seed, whereas freezing treatments did not. Eradication of M. phaseolina from mungbean seed was possible through thermotherapy. However, the conditions required for eradication also contributed to large increases in abnormal germination levels and large losses in overall germination - an unacceptable trade-off for sprouters. A combination of thermotherapy and surface sterilisation of colonised mungbean seed may provide a more efficient process of seed treatment.

The fungus Macrophomina phaseolina is the causal agent of several diseases of mungbean (Vigna radiata). One of these diseases, known as charcoal rot, causes spoilage of germinating seed lots, and occurs when seed contaminated with M. phaseolina is used for sprouting. The detection of the pathogen during seed testing prior to export leads to downgrading of the seed and a resultant financial penalty to the grain grower. The aims of this research were: to determine the location of M. phaseolina in diseased and symptomless tissue of mungbean plants; to determine the mode, site and timing of seed colonisation of mungbean; to determine the impact of biotic and abiotic factors on seed colonisation; to conduct an assessment of genotypic variation of M. phaseolina within single plants; to determine modes of transport of inoculum that contribute to foliage infection and seed colonisation of mungbean; and to assess both pre- and post-harvest management strategies in order to reduce or prevent seed colonisation, or to minimise the process of seed transmission. The location of M. phaseolina in mungbean plants was determined through serial sectioning of, and subsequent isolation from, naturally infected host tissue. A large proportion of the mungbean tissue infected by M. phaseolina was found to be symptomless. Moreover, there were large areas of ostensibly pathogen-free tissue separating infection foci, thus indicating a strong likelihood of independent aerial infections. A selection of 14 isolates obtained from serial sectioning were assessed for genotypic variation with six primers using RAPD analysis. Of the 36 bands that were scored, 78% were polymorphic and as a result, 12 distinct genotypes were detected. Polymorphisms were also detected amongst isolates obtained from the same discrete infection area on single plants, which strongly suggests the occurrence of multiple aerial infections. Various methods of controlled inoculation including soil infestation, pod and foliar inoculations, and artificial seed infestation, were used to determine how mungbean seeds are colonised by M. phaseolina. Additionally, most of these inoculation methods were coupled with a series of abiotic treatments (temperature regimes, watering regimes, application of herbicides) that were designed to initiate stress conditions within infected plants, and possibly trigger growth of M. phaseolina from the infection courts and colonise seed. Seed colonisation was established in vitro and in vivo when immature pods were directly inoculated with microsclerotia of M. phaseolina. At least two days exposure at 100% relative humidity (RH) was necessary to establish seed infection in detached mungbean pods that were inoculated with microsclerotia of M. phaseolina. Extensive seed infection was still obtained when one or more days of 100% RH was interrupted by up to three days at low humidity. All except one of the other methods of controlled inoculation failed to produce colonised seed even when combinations of stresses were applied. Only when the bipyridylium herbicide ‘Spray Seed 250’ was applied to plants following the inoculation of mungbean stems within 13 cm of the pods, was seed colonised by M. phaseolina. This result raises the possibility that delayed harvesting of desiccated mungbean crops may promote further colonisation of mungbean tissue, including seed. Very strong evidence for the colonisation of mungbean seeds after deposition of soil-splashed inoculum of M. phaseolina onto pods was obtained through field and laboratory-based studies. Soil-splashed inoculum (most likely microsclerotia) was also found to be the source of inoculum responsible for the development of Macrophomina leaf blight of mungbean at several regional sites. To further investigate this finding, areas of several mungbean crops growing in naturally infested soil were covered in hessian cloth to prevent soil-splash and assessments of the levels of seed colonisation between covered and uncovered areas were made. Although colonisation of seed in the covered areas was significantly lower than in the uncovered areas, covering the soil did not eliminate colonisation of seed. This result suggests that inoculum dispersal, leading to pod infection and subsequent seed colonisation, occurs not only in splashed-soil but also by other means. Soil transported to the extra-floral nectaries of mungbeans by ants was found to contain infective inoculum of M. phaseolina. Furthermore, air-borne debris and dust collected in a trap contained viable microsclerotia of the pathogen. Isolates of M. phaseolina collected from both sources were pathogenic on mungbean seedlings, and suspensions of ant-transported soil and air-borne dust/debris infected mungbean pods and seed. This is the first report of both modes of inoculum dispersal. All three modes undoubtedly contribute to the total level of colonised seed, but their relative importance remains to be determined. Several options for the management of charcoal rot in mungbean seeds were investigated. Application of the fungicide carbendazim to mungbean plants after flowering significantly decreased, but did not prevent, colonisation of mungbean seed by M. phaseolina. Consequently, this method of management holds little promise for mungbean growers. A large number of weeds common in Australian mungbean fields were newly reported as hosts of M. phaseolina. Isolates obtained from the infected, but symptomless weeds were pathogenic on mungbean seedlings, thus indicating a lack of host-specificity toward mungbean. It is strongly suspected that the use of herbicides to control weeds in reduced and zero-tillage farming systems is increasing the risk of infection in subsequent mungbean crops through the build-up of inoculum in soil. This increased risk of infection may be further exacerbated by retaining stubble infested with M. phaseolina on the soil surface, thereby increasing the amount of inoculum that could be splashed onto plant organs. Surface sterilisation, using sodium hypochlorite, significantly reduced colonisation levels in heavily colonised mungbean seed lines, but the process was not enhanced when a partial-vacuum was introduced to the process. In some seed lots, up to 32% of the seed was colonised only on the seed coat (defined here as contamination), whereas the remainder was internally infected. Surface sterilisation also reduced the overall colonisation of 132 commercial lines by approximately one-third. Storage of seed for one month at either 4°C or 15°C significantly reduced colonisation levels in seed, whereas freezing treatments did not. Eradication of M. phaseolina from mungbean seed was possible through thermotherapy. However, the conditions required for eradication also contributed to large increases in abnormal germination levels and large losses in overall germination - an unacceptable trade-off for sprouters. A combination of thermotherapy and surface sterilisation of colonised mungbean seed may provide a more efficient process of seed treatment.

<p>The aim of the research was to identify what female and male farmersthink are the best strategies to enhance the role of conservation farming as a buffer against social, economic and environmental hazards, and a means of ensuring livelihood sustainability and food security. The study also aimed at coming up with information useful to policy and other decision makers on how to improve adoption of these technologies. The empirical component of the research included a questionnaire survey of one hundred and fifty two(152) selected households in one identified ward in Insiza District, focus group discussions and semi-structured interviews with key informants and in-depth interviews of individual male and female members of a few selected farming households from the sampled population. The desktop portion of the study used secondary data from non-governmental organizations (NGOs), government and other stakeholders involved in conservation farming. Collected data was then disaggregated by gender and analyzed using the Statistical Package for the Social Sciences (SPSS). Perception statements that emerged as significant in chi-square tests of independence were be subjected to factor analysis and weighted factor scores from factor analysis were then used as independent variables in binary logistic regression analysis. The study concluded that both practising and non practising farmers were of the opinion that conservation farming was good though they indicated that information on conservation farming was not readily available The study found out that most farmers agreed on the possible positive effects of CA in addressing livelihood challenges effected by hazards such as HIV and AIDS and environmental hazards such as declining soil fertility but it had is labour intensive therefore is not suitable for people affected and infected by HIV and AIDS...</p>

<p>The aim of the research was to identify what female and male farmersthink are the best strategies to enhance the role of conservation farming as a buffer against social, economic and environmental hazards, and a means of ensuring livelihood sustainability and food security. The study also aimed at coming up with information useful to policy and other decision makers on how to improve adoption of these technologies. The empirical component of the research included a questionnaire survey of one hundred and fifty two(152) selected households in one identified ward in Insiza District, focus group discussions and semi-structured interviews with key informants and in-depth interviews of individual male and female members of a few selected farming households from the sampled population. The desktop portion of the study used secondary data from non-governmental organizations (NGOs), government and other stakeholders involved in conservation farming. Collected data was then disaggregated by gender and analyzed using the Statistical Package for the Social Sciences (SPSS). Perception statements that emerged as significant in chi-square tests of independence were be subjected to factor analysis and weighted factor scores from factor analysis were then used as independent variables in binary logistic regression analysis. The study concluded that both practising and non practising farmers were of the opinion that conservation farming was good though they indicated that information on conservation farming was not readily available The study found out that most farmers agreed on the possible positive effects of CA in addressing livelihood challenges effected by hazards such as HIV and AIDS and environmental hazards such as declining soil fertility but it had is labour intensive therefore is not suitable for people affected and infected by HIV and AIDS...</p>

Magister Philosophiae - MPhil / The aim of the research was to identify what female and male farmersthink are the best strategies to enhance the role of conservation farming as a buffer against social, economic and environmental hazards, and a means of ensuring livelihood sustainability and food security. The study also aimed at coming up with information useful to policy and other decision makers on how to improve adoption of these technologies. The empirical component of the research included a questionnaire survey of one hundred and fifty two(152) selected households in one identified ward in Insiza District, focus group discussions and semi-structured interviews with key informants and in-depth interviews of individual male and female members of a few selected farming households from the sampled population. The desktop portion of the study used secondary data from non-governmental organizations (NGOs), government and other stakeholders involved in conservation farming. Collected data was then disaggregated by gender and analyzed using the Statistical Package for the Social Sciences (SPSS). Perception statements that emerged as significant in chi-square tests of independence were be subjected to factor analysis and weighted factor scores from factor analysis were then used as independent variables in binary logistic regression analysis. The study concluded that both practising and non practising farmers were of the opinion that conservation farming was good though they indicated that information on conservation farming was not readily available The study found out that most farmers agreed on the possible positive effects of CA in addressing livelihood challenges effected by hazards such as HIV and AIDS and environmental hazards such as declining soil fertility but it had is labour intensive therefore is not suitable for people affected and infected by HIV and AIDS. / South Africa

<p>New technology and new innovations have for long been considered as a spring for growth. Conservation farming (CF) is a new production method introduced in rural Zambia and previous research shows that it increases yields and improves soil fertility. Even though the method is proven more efficient than conventional agriculture, only approximately 10 % of Zambia’s farmers have adopted the method. The purpose of this study is to discuss the implications of the introduction of CF on the capabilities of farmers and on economic growth. Furthermore, the study aims to explore why CF, which is proven to be more economically efficient than the conventional method, is not adopted to a larger extent in Zambia.</p><p>A qualitative study of 25 farmers, farming with either CF or conventional methods, was performed in the region of Mumbwa, Zambia. The results were divided depending on whether the farmers were using the new method or not. To analyze the selected material theories were chosen that regard economic growth and technological change, the adoption process of new innovations, incentive creation and the expansion of capabilities.</p><p>The two groups showed differences in age, the size of their land, how many crops they grew and to what extent they were working for others or hiring labor. The conclusion from the small sample of farmers is that the farmers using CF had been able to expand their capabilities in different ways. They had food for all the year, the new method allowed them to plan their time better and it was more environmentally sustainable than the old method. The negative aspect of CF is that it is not compatible with the old method in terms of social norms. CF leads to a more efficient use of capital and labor and therefore it can increase the economic growth. In terms of a new innovation, CF seems to have a relative advantage over the old method but it must be spread to a larger group of farmers to reach a breakthrough. To create a higher adoption rate of the method the farmers’ perception must be taken into account.</p> / Minor Field Study (Sida)

New technology and new innovations have for long been considered as a spring for growth. Conservation farming (CF) is a new production method introduced in rural Zambia and previous research shows that it increases yields and improves soil fertility. Even though the method is proven more efficient than conventional agriculture, only approximately 10 % of Zambia’s farmers have adopted the method. The purpose of this study is to discuss the implications of the introduction of CF on the capabilities of farmers and on economic growth. Furthermore, the study aims to explore why CF, which is proven to be more economically efficient than the conventional method, is not adopted to a larger extent in Zambia. A qualitative study of 25 farmers, farming with either CF or conventional methods, was performed in the region of Mumbwa, Zambia. The results were divided depending on whether the farmers were using the new method or not. To analyze the selected material theories were chosen that regard economic growth and technological change, the adoption process of new innovations, incentive creation and the expansion of capabilities. The two groups showed differences in age, the size of their land, how many crops they grew and to what extent they were working for others or hiring labor. The conclusion from the small sample of farmers is that the farmers using CF had been able to expand their capabilities in different ways. They had food for all the year, the new method allowed them to plan their time better and it was more environmentally sustainable than the old method. The negative aspect of CF is that it is not compatible with the old method in terms of social norms. CF leads to a more efficient use of capital and labor and therefore it can increase the economic growth. In terms of a new innovation, CF seems to have a relative advantage over the old method but it must be spread to a larger group of farmers to reach a breakthrough. To create a higher adoption rate of the method the farmers’ perception must be taken into account. / Minor Field Study (Sida)

Text in English / The study analysed the effects of conservation farming in Zimbabwe using a mixed methodology approach. This analysis comes against the background of the recognition that climate change, as characterized by severe droughts, has played a significant role in reducing agricultural productivity, in the process leaving smallholder farmers and the nation of Zimbabwe exposed to recurrent food insecurity. Conservation farming was introduced as a climate adaptation strategy that was aimed at improving crop yields. The study focused on assessing the association between the adoption of conservation farming and a concomitant increase in agricultural productivity. This was key in understanding if there are benefits of using conservation farming as opposed to making use of the conventional method of farming. The study also investigated the nature of conservation farming being practiced in Umguza District; this was done in order to understand whether smallholder farmers are implementing all the key principles underpinning the use of conservation farming. The study further assessed the challenges and opportunities that exist through the use of conservation farming with the aim of coming up with sustainable solutions to the challenges affecting smallholder farmers. The study went on to assess the factors that determine the adoption and maximum utilization of conservation farming. Identification of these key variables was instrumental in the design of a localized conservation farming model. Study results revealed that conservation farming is an effective method of increasing agricultural productivity. The study also established that smallholder farmers are not implementing all the key principles of conservation farming and this was attributed to the failure to include the smallholder farmers in the design of conservation farming models. It was further revealed that smallholder farmers face various challenges that include access to inputs and limited support from the government. Implications of the study highlight the need for the community to be actively involved in the design of a conservation farming model localized to the unique context of smallholder farmers. A prototype for implementing a sustainable conservation farming model was developed in collaboration with the smallholder farmers as part of a solution based approach to dealing with the challenges affecting smallholder farmers. / School of Agriculture and Life Sciences / Ph. D.