Official statistics suggest that as many as 40 percent to 60 percent of people in South Africa are living in poverty, and the 15 percent poorest are in a desperate struggle for survival. Since 1994, Government has been making an effort to help smallholder agriculture through numerous programmes, including those that address land ownership and provide credit and grants for farms and households, but very little change has taken place. Understanding the sources of livelihood and opportunities to improve the contribution of farming within available food chains is therefore an important practical need. The study investigated sources of livelihood and mapped the livelihoods profile of the farming households in parts of the Eastern Cape. The study was conducted in the Alice and Peddie communities in the Amathole district municipality. A set of structured questionnaires were used to interview the sample of 80 farming households selected through a random process within two irrigation schemes and communities that were selected purposively in line with the focus of the larger project on which this study is based. The resulting data were analyzed by means of descriptive statistics and multiple linear regression. The descriptive results indicated that members of most rural households were old, married, uneducated and unemployed. Farming was primary livelihood strategy employed in these areas. Rural households were also dependent on remittances, social grants and pension funds because the farming strategy could not meet all their household needs. The major crops that were grown for income and food security to sustain their livelihoods included maize, potatoes, onions and butternut. Factors that had significant influences on outcomes were extension services, grants, pension and remittances, land productivity, type of irrigation system, market accessibility, output price difference and value adding. The available opportunities were land productivity, irrigation facilities, government or NGO programmes and working as a group. For improved livelihood of rural communities in Alice and Peddie, government needs to strengthen agricultural activities and equip farmers with market information, improve their access to irrigation schemes, provide training on value adding and also improve access to extension services.

Kleinbäuerliche Haushalte im Globalen Süden sind zunehmend gefordert, ihre landwirtschaftlichen Aktivitäten an globale Veränderungen anzupassen. Landwirtschaftliche Beratungsdienste (extension services) stoßen vielerorts auf Schwierigkeiten, eine wachsende rurale Bevölkerung mit heterogenen Informationsbedürfnissen adäquat zu erreichen. Die zunehmende Verbreitung moderner Informations- und Kommunikationstechnologien (IKT) hat in jüngster Zeit neue Möglichkeiten geschaffen, Information weitreichend zu verbreiten. Gleichzeitig bietet digitale Kommunikation aber auch Möglichkeiten, große Zahlen von Bäuerinnen und Bauern in der Erzeugung von Wissen und Information einzubinden. Durch digitale Kanäle können landwirtschaftliche Beratungsdienste systematisch Daten-Inputs von ihrer Zielgruppe erheben, sie aggregiert verarbeiten, und auf dieser Grundlage ihre Dienstleistung verbessern. Diese Dissertationsschrift präsentiert drei Machbarkeitsstudien zu verschiedenen Strategien zur Einbindung großer Zahlen von Bäuerinnen und Bauern in der landwirtschaftlichen Beratung mittels moderner IKT. Eine erste Studie untersucht die Machbarkeit und den Nutzen digital unterstützter landwirtschaftlicher „Bürgerwissenschaft“ (citizen science) zur Einbindung von Bäuerinnen und Bauern in der Wissensgenerierung. Eine zweite Studie passt den „Positive Deviance-Ansatz“ an multi-dimensionale kleinbäuerliche Entwicklung an. Eine dritte Studie präsentiert und testet ein Verfahren zur Nutzung von „Zwei-Wege-Kommunikation“ über Mobiltelefone, um die automatisierte, individuelle Priorisierung von Beratungsinhalten in kleinbäuerlichem Kontext zu verbessern. Auf Basis der vorgelegten Erkenntnisse aus drei unabhängigen Machbarkeitsstudien macht die Dissertationsschrift Vorschläge, wie landwirtschaftliche Beratungsdienste im Globalen Süden die Herausforderungen der großen Zahl und starken Heterogenität kleinbäuerlicher Haushalte mit effizienter, systematischer Nutzung digitaler Medien begegnen können. / Smallholder farmers across the Global South increasingly need to adapt their farming activities to fast-paced changes. Worldwide, agricultural extension services face the challenge of reaching a large and growing clientele with highly diverse information needs. In recent years, increased penetration of modern information and communication technology (ICT) has created new opportunities for disseminating agricultural information. At the same time, digital communication can also allow the involvement of large numbers of farmers in the creation and aggregation of relevant knowledge and information. By collecting well-defined data inputs from farmers and processing these data in systematic ways, agricultural advisory services can potentially improve their overall performance towards a large and heterogeneous clientele. Through three proof-of-concept studies, this dissertation delivers empirical evidence on the feasibility of different ways of employing modern ICT to harness large-scale farmer participation in agricultural extension. A first study explores the feasibility and usefulness of digitally-enabled agricultural citizen science for involving large numbers of farmers in knowledge generation. A second study adapts the ‘Positive Deviance approach’ to multi-dimensional agricultural development and delivers evidence on its feasibility. A third study suggests and tests a procedure for employing two-way communication through mobile phone interfaces for improving the targeting of agricultural advisory messages in smallholder context. Based on the empirical evidence from these three independent proof-of-concept studies, the dissertation suggests how agricultural extension services in the Global South can address the challenges of scale and complexity in smallholder farming context through increased methodological pluralism, greater farmer participation, and efficient, systematic use of digital media.

En 2008, la Banque mondiale a consacré son « rapport annuel sur le développement » à l'agriculture. Cela n’avait plus été le cas depuis 25 ans. Elle y montre que la croissance agricole est plus efficace que celle d’autres secteurs pour réduire la pauvreté. La productivité du travail agricole des actifs agricoles y est paradoxalement à peine citée : ses facteurs explicatifs de court terme comme ses variables structurantes sur le long terme ne sont pas analysés. Cette thèse entend contribuer à une meilleure compréhension des relations dynamiques qu’entretiennent la démographie et le développement non agricole avec le développement agricole (élévation de la productivité du travail agricole). Sous quelles conditions démo-économiques la transformation structurelle d'une économie (baisse du poids relatif du secteur agricole dans l’économie (actifs et valeur ajoutée)) peut-elle s'accompagner d'un développement agricole ? Alors qu’un secteur industriel ou tertiaire qui se développe est généralement attracteur d’actifs, une loi inverse existe-t-elle pour le secteur agricole ? Celui-ci doit-il nécessairement se vider de ses actifs pour se développer ? Y’a-t-il jamais eu, et peut-il y avoir développement agricole dans un contexte de croissance continue du nombre des actifs agricoles ?Notre (hypo)thèse principale est que la combinaison dynamique des facteurs «terre » et «actif agricole », dont la résultante est la « surface travaillée par actif agricole », est la véritable clé du développement agricole, davantage que la productivité de la terre. Nous analysons les déterminants des niveaux et taux de croissance de la productivité du travail agricole au cours de la période 1980 - 2007, à différentes échelles géographiques. Une attention particulière est mise sur la variable « nombre d’actifs agricoles », à l'aide de différents jeux de données (internationales, nationales, données d’enquêtes de terrain), à différentes échelles (monde, Mexique, 31 états fédérés et 2400 Municipes mexicains) et avec diverses méthodes (décomposition factorielle, cartes, classifications ascendantes hiérarchiques, inférence statistique, enquêtes de terrain auprès de ménages agricoles, non agricoles, d’institutions). Au niveau mondial, nous mettons en évidence une « course de vitesse » entre actifs agricoles et terre dans certaines régions du monde et proposons le concept de «transition agricole démographique » ainsi que sa typologie associée. Le Mexique est ensuite choisi pour ses agricultures présentant des niveaux de développement très contrastés, en synchronie comme en diachronie. Nous cherchons à expliquer les différences de trajectoires de développement agricole observées au Mexique. Nous analysons l’influence de variables caractérisant l’économie non agricole, la substitution du capital machine au travail, la libéralisation foncière, la géographie (physique et humaine). Dans les comparaisons internationales comme au Mexique, nous montrons que le taux de croissance de la surface par actif agricole a une influence marginale plus forte sur le taux de croissance de la productivité du travail agricole, que le taux de croissance de la productivité de la terre. Enfin, nous analysons les stratégies économiques de ménages et actifs agricoles, du Municipe de Teopisca dans la région de Los Altos de Chiapas, « piégés » dans un contexte de « transition agricole démographique bloquée » (décroissance tendancielle de la surface travaillée par actif) : diversification des sources de revenus (vers le non agricole) et tentatives d’élévation de la productivité de la terre sont les deux principales stratégies déployées sous contraintes de défaillances des marchés (travail, crédit) et d’accès à l’eau d’irrigation. / In 2008, the World Bank has dedicated its "Annual Report on Development" to agriculture. This had not been the case for 25 years. It shows that agricultural growth is more effective than other sectors to reduce poverty. The agricultural labor productivity of the agricultural workforce is paradoxically barely mentioned: its explanatory factors for the short term as its structural variables in the long term are not analyzed. This thesis aims to contribute to a better understanding of the dynamic relationship between demography and non-agricultural development with agricultural development (increased productivity of agricultural labor). Under what demo-economic conditions can the structural transformation of an economy (i.e. the decline in the relative weight of the agricultural sector in the economy (workers and value added)) be accompanied by agricultural development? While an industrial or service sector that develops generally attracts workers, is there an opposite relationship in the agricultural sector? Does the agricultural sector have to lose its workers to develop? Has an agricultural sector ever developed in a context of continuous growth in the number of agricultural workers? Our main (hypo)thesis is that the dynamic combination of factors « land » and « agricultural worker », whose resultant is the « agricultural area worked per agricultural worker », is the real key to agricultural development, more than the productivity of the land.We analyze the determinants of the level and of the growth rate of the agricultural labor productivity over the 1980-2007 period, at different geographical levels. Special focus is put on the evolution of the « number of agricultural workers », using different sets of data (international, national, field surveys data), at different scales (world, Mexico, and 31 federal states 2400 Mexican municipalities) and with various methods (factor decomposition, maps, hierarchical ascending classifications, statistical inference, field surveys of farming households).Globally, we highlight a « race » between land and the number of agricultural workers in certain regions of the world and propose the concept of « demographic transition agriculture » and its associated typology.Mexico is then chosen for its agriculture showing very contrasting levels of development, for both synchronic and diachronic observation. We seek to understand the differences in agricultural development paths observed in Mexico by analyzing the influence of variables characterizing the non-farm economy, the substitution of machinery capital for labor, land liberalization, geography (physical and human).In international comparisons as within Mexico, we show that the growth rate of the area by agricultural worker has a marginally stronger influence on the growth rate of agricultural labor productivity, than the growth rate of land productivity.Finally, in the Municipality of Teopisca in the Los Altos region of Chiapas, we analyze the economic strategies of farm households « trapped » in a context of « blocked demographic agricultural transition » (downward trend of the agricultural area per worker): income diversification (toward the non-agricultural sector) and attempts to rise the land productivity are the two main strategies deployed under local severe constraints of market failures (labor, credit) and difficult access to irrigation water.

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.

<p>Cadmium (Cd) is a highly mobile and toxic heavy metal that negatively affects plants, soil biota, animals and humans, even in very low concentrations. Currently, Cd contamination of cocoa produced in Latin American countries is a significant problem, as concentrations can exceed acceptable levels set by the European Union (0.5 mg/kg), sometimes by more than 10 times allowable levels. In South America, <i>Theobroma cacao</i> is an essential component of the basic market basket. This crop contributes to the Latin-American trade balance, as these countries export cacao and chocolate-based products to major consumer countries such as the United States and Europe. Some soil amendments can alter the bioavailability and uptake of Cd into edible plant tissues, though cacao plants can accumulate Cd without displaying any visible symptoms of phytotoxicity, which makes it difficult to determine if potential remediation strategies are successful. Currently, the only effective way to quantify Cd accumulation in plant tissues is via destructive post-harvest practices that are time-consuming and expensive. New hyperspectral imaging (HSI) technologies developed for use in high-throughput plant phenotyping are powerful tools for monitoring environmental stress and predicting the nutritional status in plants. Consequently, the experiments described in this thesis were conducted to determine if HSI technologies could be adapted for monitoring plant stress caused by Cd, and estimating its concentration in vegetative plant tissues. Two leafy green crops were used in these experiments, basil (<i>Ocimum basilicum L.</i> var. Genovese) and kale (<i>Brassica oleracea L</i>. var. Lacinato), because they are fast growing, and therefore, could serve as indicator crops on cacao farms. In addition, we expected these two leafy green crops would differ in their morphological responses to Cd stress. Specifically, we predicted that stress responses would be visible in basil, but not kale, which is known to be a hyperaccumulator. The plants were subject to four levels of soil Cd (0, 5, 10 and 15 ppm), and half of the pots were amended with biochar at a rate of 3% (v/v), as this amendment has previously been demonstrated to improve plant health and reduce Cd uptake. The experiments were conducted at Purdue’s new Controlled Environment Phenotyping Center (CEPF). The plants were imaged weekly and manual measurements of plant growth and development were collected at the same times, and concentrations of Cd as well as many other elements were determined after harvest. Fourteen vegetation indices generated using HSI images collected from the side and top view of plants were evaluated for their potential to identify subtle signs of plant stress due soil Cd and the biochar amendment. In addition, three mathematical models were evaluated for their potential to estimate Cd concentrations in the plant biomass and determine if they exceed safe standards (0.28 mg/kg) set by the Food and Agriculture Organization (FAO) for leafy greens. Results of these studies confirm that like many plants, these leafy green crops can accumulate Cd levels that are well above safety thresholds for human health, but exhibit few visible symptoms of stress. The normalized difference vegetation index (NDVI) and the chlorophyll index at the red edge (CI_RE) were the best indices for detecting Cd stress in these crops, and the plant senescence and reflectance index (PSRI) and anthocyanin reflectance index (ARI) were the best at detecting subtle changes in plant physiology due to the biochar amendment. The heavy metal stress index (HMSSI), developed exclusively for detecting heavy metal stress, was only able to detect Cd stress in basil when images were taken from the top view. Results of the mathematical models indicated that principal components analysis (PCA) and partial least squares (PLS) models overfit despite efforts to transform the data, indicating that they are not capable of predicting Cd concentrations in these crops at these levels. However, the artificial neural networks (ANN) was able to predict whether leafy greens had levels of Cd that were above or below critical thresholds suggested by the FAO, indicating that HSI could be further developed to predict Cd concentrations in plant tissues. Further research conducted in the field and in the presence of other environmental stress factors are needed to confirm the utility of these tools, and determine whether they can be adapted to monitor Cd uptake in cacao plants.</p>

<p>Poor food safety in informal, open-air markets remains a pressing issue in Cambodia, contributing to both foodborne illness and malnutrition. In order to design food safety programs that successfully promote positive food safety practices among the various actors involved in these markets, is important to understand their perceptions of food safety and of their own capability, opportunity, and motivation for adopting positive food safety behaviors. To that end, this research sought to explore and describe the perceptions of vegetable vendors, vegetable distributors, and vegetable growers in the Cambodian provinces of Battambang, Siem Reap, and Phnom Penh regarding food safety and their own personal capability, opportunity, and motivation for implementing specific food safety practices.  To note, this research was made possible by the generous support of the American people through the United States Agency for International Development (USAID) though Cooperative Agreement No. 7200AA19LE00003 to Purdue University as management entity of the Feed the Future Innovation Lab for Food Safety. The contents are the responsibility of the authors and do not necessarily reflect the views of USAID or the United States Government. </p> <p>The first portion of the research, which examined levels of perceived capability, opportunity, and motivation for positive food safety practices among actors involved in informal vegetable markets in Cambodia, employed a quantitative questionnaire based on the Capability, Opportunity, Motivation-Behavior model of behavior and the Theoretical Domains Framework. A pilot study using this questionnaire was performed with vegetable vendors in the Province of Phnom Penh (<em>N</em> = 55), after which the questionnaire was revised and implemented in person with vegetable distributors in Battambang Province (<em>n</em> = 37) and vegetable vendors and growers in Battambang (<em>n</em> = 26 and <em>n</em> = 27, respectively) and Siem Reap Provinces (<em>n</em> = 61 and <em>n</em> = 30, respectively). To validate the questionnaire, response data from participants in Battambang and Siem Reap were evaluated using confirmatory factor analysis. The resultant nine-factor model had a comparative fit index of .91, a Tucker-Lewis index of .89, and a root mean square error of approximation of .05. Data analysis proceeded using a fitted general linear mixed model. Results of this analysis suggested that levels of perceived motivation and capability for the target food safety practice were typically significantly higher (<em>p</em> < .05) than levels of perceived opportunity among vegetable vendors and distributors, regardless of location. Levels of perceived opportunity and perceived capability were significantly lower (<em>p</em> < .05) than levels of perceived motivation among vegetable growers in both Battambang and Siem Reap. Significantly higher (<em>p</em> < .05) levels of perceived opportunity and motivation for the target food safety practice were observed among vendors in Battambang in comparison to vendors in Siem Reap; perceptions of all three behavioral determinants were higher among vendors in Battambang than among farmers in either location. </p> <p>Subsequently, a quantitative questionnaire regarding participants’ perceptions of vegetable safety was implemented in person with vegetable growers in Battambang (<em>n </em>= 41) and Siem Reap (<em>n</em> = 28) and vegetable vendors in Phnom Penh (<em>n </em>= 31). Response data were analyzed using a fitted logistic regression model. Nearly all respondents indicated that they were concerned about vegetable safety (overall mean estimate 97.4%, 95% CI = [89.7, 99.4]%), with ≤ 62.7% of respondents in all groups reporting at least moderate concern (lower bounds of 95% confidence intervals 46.2% at the lowest). Across all groups, chemical contamination was perceived as more concerning than microbial contamination (84.9%, 95% CI = [76.0, 90.9]%). The majority of respondents reported that they were familiar with the potential health effects of consuming vegetables contaminated with either chemicals (71.4% [61.5, 79.6]%) or microbes (57.3% [47.2, 66.9]%). Nonetheless, when those who reported familiarity were asked to give examples of such health effects, fewer than 50% (ranging from 7.3% to 48.4%) provided an example of a commonly understood health effect of consuming contaminated vegetables. </p> <p>Both chemical and microbial contamination were most frequently perceived as occurring mainly “at the farm”, regardless of participants’ occupation and location (≥ 76.7%, lower bounds of 95% confidence intervals at least 61.5%, and ≥ 39.3%, lower bounds of 95% confidence intervals at least 21.2%, respectively). Correspondingly, “vegetable farmers’ were most often perceived as having the greatest responsibility for chemical contamination prevention (≥ 51.6% across all groups, lower bounds of 95% confidence intervals at least 34.0%). There were significant between-group differences in participants’ perceptions of microbial contamination prevention responsibility, however (<em>p</em> = .02). With regards to practices intended to prevent vegetable contamination, 22.6% of surveyed vendors in Phnom Penh, 39.0% of surveyed growers in Battambang, and 53.6% of surveyed growers in Siem Reap described at least one commonly accepted contamination prevention practice. </p> <p>Considered as a whole, these findings indicate that food safety practice adoption may be more effectively encouraged among vegetable growers, distributors, and vendors in Phnom Penh, Battambang, and Siem Reap by emphasizing the importance of microbial contamination and integrating educational components regarding the health effects of consuming vegetables contaminated with microbes or chemicals into food safety programs. Such programs should also address the relatively lower levels of perceived opportunity present among all groups; environmental restructuring-based interventions may be one means by which to do so. Programs for vegetable vendors specifically should communicate that microbial contamination of vegetables is common and highlight the significance of the role of vegetable vendors in maintaining a safe vegetable supply. Food safety programs tailored to vegetable growers could draw on growers’ perception of their own responsibility for both vegetable contamination and contamination prevention as well as their perception of contamination as a common occurrence. Programs for vegetable growers also need to incorporate efforts to address the relatively lower levels of perceived capability present within this group. These efforts could include educational programming or hands-on demonstrations that increase participants’ perceptions of their own ability to implement positive food safety practices. </p>

<p dir="ltr">The striped cucumber beetle (<i>Acalymma vittatum</i>) is a leading pest across a variety of cucurbit crops in eastern North America. These beetles can rapidly infest and damage a field, leading to frequent insecticide applications to manage them. Chemical control is effective at reducing beetle populations, but it also causes detrimental non-target effects on pollinators, which are essential for cucurbit yield. Developing a holistic IPM (integrated pest management) approach is necessary to manage pests while avoiding non-target effects in cucurbit production systems. </p><p dir="ltr">A unique and well-characterized behavior of striped cucumber beetles is their olfactory attraction to both plant volatiles and their species-specific aggregation pheromone, vittatalactone. The interacting effects of combining these olfactory stimuli for cucumber beetle attraction have not previously been tested. I expected when presented with plant volatiles and pheromone together, the striped cucumber beetles will show synergistic attraction, resulting in enhanced attraction stronger than the sums of the separate effects. Along with targeting striped cucumber beetles, I expected to elicit cross-attraction of related cucurbit pests (e.g., spotted cucumber beetle) to these same signals based on previous findings indicating cross-attraction. The expected cross attraction may be due to the reliance on olfactory cues to inform the related insects on preferrable host plants and nutrition. </p><p dir="ltr">Cucurbit systems are also highly reliant on pollination services for high-quality fruit; thus, the feasibility of these semiochemical tools depends on their influence on pollinator behavior. I expect pollinators to be attracted to floral volatiles but not vittatalactone or individual plant volatiles without the full complement of floral scent (e.g., indole, leaf volatiles). Altogether, this research aims to develop a targeted management tool for striped cucumber beetles and other cucurbit pests, while avoiding pollinator distraction or other detrimental effects.</p><p dir="ltr">To measure the efficacy of using olfactory signals as attractants, clear sticky cards were deployed in the field with combinations of pheromone paired with volatiles (floral and/or leaf), as well as the individual components, to quantify pest responses. Simultaneously, a pan trap sampling method was implemented to measure pollinator responses to the same semiochemical combinations. The results of the study demonstrate that striped cucumber beetles are strongly attracted to volatile lures containing pheromones, floral volatiles, and combinations of the two, although the combined pheromone and floral volatile treatments did not synergize beetle attraction. </p><p dir="ltr">Though combined lures did not synergize attraction, this data demonstrates additive effects on beetle behavior. The findings also highlight the importance of understanding seasonal disparities between the behavior of early and late generations of striped cucumber beetles. Temporal variation in attraction demonstrated by the pests is crucial to understand when to implement lure-based management strategies. Two years of testing floral volatile and herbivory-induced plant volatile (HIPV) lure treatments on key cucurbit pollinators showed varying levels of attraction. There was no attraction of focal cucurbit bees to the striped cucumber beetle pheromone, but there were differences in the response of pollinators to plant volatile components. </p><p dir="ltr">Cucurbits require high pollination activity for successful fruit, though the most important bees in pollinating this system are bees belonging to the genera, <i>Apis</i> and <i>Eucera</i>. Along with these bee groups, other bees such as those belonging to <i>Melissodes</i>, <i>Lasioglossum</i>, and <i>Bombus</i> are also known important pollinators. <i>Lasioglossum</i> bees showed a strong attraction to the full-floral blend, TIC (1,2,4-trimethoxybenzene, indole, (E)-cinnamaldehyde), but no preference for indole or HIPVs. <i>Melissodes</i> bees were most attracted to methyl salicylate and TIC, whereas <i>Eucera</i> bees exhibited strong attraction to ocimene and TIC. These findings suggest that different pollinator taxa have unique preferences for plant volatiles, highlighting the importance of optimizing lure combinations to avoid disrupting pollination activities in cucurbit production.</p><p dir="ltr">Additionally, this study revealed that other key cucurbit pests, such as spotted cucumber beetles and western corn rootworms, also showed strong attraction to the tested volatile components. These findings suggest that the selected volatiles may have broader implications for pest management beyond striped cucumber beetles. Further research is needed to fully understand the efficacy and refine formulations of these volatile lures to implement in IPM.</p>

<p dir="ltr">Corn, a vital cereal grain extensively used in various industries, exhibits viscoelastic properties when subjected to compressive forces. The effect of moisture content on the mechanical behavior of corn is crucial for understanding its storage, processing, and transportation requirements. Understanding the mechanical properties of bulk corn is crucial for ensuring a smooth flow of grains from the bin, thereby helping to prevent confined space-related accidents such as grain bin entrapment and engulfment, which can occur when workers enter the bin to facilitate grain flow. The objective of this study is to investigate the stress and strain relaxation of different bulk corn kernels qualities. In the first study various qualities of bulk corn, including clean corn, corn with impurities, and moldy corn samples were compressed at 42, 77, 106, and 130 N force levels. The compressive behavior of samples was measured at 13.22, 16.16, 18.93, and 21.70% wet basis moisture contents. The samples were compressed at a strain rate of 1.25mm/min, and the strain was kept constant for 200 s to determine the stress relaxation properties. For moldy corn, the energy absorbed increased with force resulting in clump formation irrespective of the force level. In the clean corn, the energy absorbed increased with moisture content, and formation of clumps was observed at 21.70% moisture content. Solidity decreased with moisture content, resulting in high cohesion at moisture contents 18.93% and 21.70% for clean corn. In corn with impurities, even though the energy absorbed increased with moisture content, no clump formation was observed. This study provides insights into the mechanical behavior of bulk corn under compression, such as solidity and compressive strength. An increase in the compressive strength or a decrease in the solidity of stored shelled corn in a grain bin increases compaction, cohesion, and the formation of clumps, and thereby affects the flow of grains during discharge from the bin. The study also highlights potential risks in grain bins when the kernels are moldy and stored at high moisture content.</p><p dir="ltr">The second study investigates the creep behavior of bulk corn kernels and its relationship with moisture content. Clean corn reconditioned to 16.23%, 19.02%, and 21.63% from the initial moisture content of 10.81% were compressed at 42, 77, 106, and 130 N. The viscoelastic behavior of the sample was measured by fitting the experimental data to a four-element Burgers model to obtain the model parameters E₀, E₁, η₀, and η₁. The results showed that the ranges of the elastic modulus (E₀) increase with an increase in moisture content, indicating an increase in compaction and elastic deformation of the sample. Retarded elastic modulus (E₁) values were also high at high moisture content, implying a high absorption of energy. The viscous component shows a dominance of the elastic component due to the low value of η₁ at high moisture content. The findings highlight the importance of considering moisture content in optimizing the handling of corn to enhance safety and efficiency in agricultural operations. Increase in the elastic modulus, retarded elastic modulus, and decrease in the viscous component leads to poor discharge of grains from the bin due to grain bridging or crust, or formation of clump due to out-of-conditioned grain, leading to a potential risk of grain entrapment and engulfment when the grain bin workers get inside the bin. This research contributes to the ongoing efforts to improve grain storage conditions.</p>

This study investigates some of the issues affecting participation of the poor in two development projects in Inkosikazi communal lands in Zimbabwe. Recent trends in participatory development are reviewed and discussed in the study. Some definitions of the concept of participation are explored, including its historical background, importance and challenges. Fieldwork was undertaken in Inkosikazi communal lands in July 2004. Two projects were randomly sampled, and in one of them involving goat-rearing, some of the participants were classified as being very poor, while in the other, a heifer loan-scheme project, none of the participants could be classified as very poor. The possible reasons for these variations are explored in the study. The conclusion of the thesis is that the study succeeds in examining certain key issues affecting participation of the poor in Inkosikazi communal lands in Zimbabwe and recommendations thereof are made. / Development Studies / M.A. (Development Studies)

M.Sc.(Geography) / This study aimed at examining the social and economic impact of rural irrigation schemes with a particular focus on the Lower Gweru Irrigation scheme. The general objective of this study was to assess if rural irrigation schemes can act as livelihood security assets in transforming rural livelihoods, reduce poverty and attain food security in light of climate change. Results are based on findings from self-administered questionnaires directed at farmers and irrigation stakeholders, and face to face interviews involving farmers and stakeholders. Using Statistical Package for the Social Sciences, Microsoft excel and Health 24 web BMI calculator it was concluded that; Lower Gweru schemes, is a source of livelihood security securing food security, reduce poverty and creates rural employment. Regardless of various challenges faced by rural irrigation farmers, irrigations act as poverty and climate change buffers, providing an opportunity for communities to raise their Human Development Index and attain sustainable development. / Department of Geography