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Bibliography: leaves 165-195., The transfer of T-DNA from Agrobacterium tumefaciens to eukaryotic cells is on of the most extensively studied examples of interkingdom DNA transfer. This transfer system has revolutionized plant molecular biology to the extent that the introduction of foreign genes into plant genomes is now a basic technique. Apart from the finding that a defined segment (T-DNA) of the A. tumefaciens Ti plasmid can be transferred to plant DNA, the discovery that the mobilization functions of the IncQ plasmid, RSF1010, can mediate its transfer from A. tumefaciens into plant cells as well between Gram negative bacteria has generated considerable interest. The mobilization functions of RSF1010 substitute for the requirement of the 25-bp border T-DNA sequences of A. tumefaciens. In this thesis I investigated the ability of another plasmid, pTF-FC2, to transfer genes to plants.

Studies are scarce linking planned farmer adaptation practices with their actual practices over time. This study addresses this gap by investigating planned and actual adaptation behaviour, using data collected in 2014 and 2017, from various irrigation schemes in south-eastern Africa. Four planned farm adaptation indexes were created and analysed, with findings suggesting that land size, previous adaptation experience and credit access were positively associated with all types of adaptation. The results from the two waves of survey analysis also indicated very different influences between planned and actual practices, with the proportion of farmers actually undertaking a particular practice far greater than those who planned to undertake it. This result might be related to the project intervention within the study schemes, where numerous factors previously hampering irrigation were resolved, increasing farmers' ability to adapt. Enhancing the availability and quality of education, extension services and finance could be valuable in encouraging further farm adaptation. Refereed/Peer-reviewed

usc Successful irrigated agriculture is underpinned by answering two critical questions: when and how much to irrigate. This article quantifies the role of the Chameleon and the Wetting Front Detector, monitoring tools facilitating decision-making and learning about soil-water-nutrient dynamics. Farmers retained nutrients in the root zone by reducing irrigation frequency, number of siphons, and event duration. Water productivity increased by more than 100% for farmers both with and without monitoring tools. Transitioning smallholder irrigation systems into profitable and sustainable schemes requires investment in technology, farmers and institutions. Importantly, technologies need embedding in a learning environment that fosters critical feedback mechanisms, such as market constraints. Refereed/Peer-reviewed

usc This article explores the value of Ostrom’s socio-ecological systems framework and Meadows’s leverage point hierarchy, as structured diagnostics, to define systemic problems and avoid approaches based on linear thinking. These frameworks were applied as an ex post analysis of an irrigation scheme in Zimbabwe, drawing on the scheme’s baseline condition and the intervention outcomes. Strong leverage points, particularly those driving feedback mechanisms and institutional design, interacted with other intervention points, initiating systemic change. This analysis suggests that dysfunctional schemes can be transitioned towards complex adaptive systems by using agricultural innovation platforms to identify systemic challenges and intervention points. Refereed/Peer-reviewed