Search

The pitcher trap rim of Nepenthes (the peristome) is a highly specialised plant surface that holds unique micro-structuring, unlike any other leaf. The mature peristome exhibits a hierarchical microtopography of radial grooves and ridges, rendering this surface highly wettable, and anti-adhesive to insect feet when wet. The function of the peristome as a slippery trapping surface is well documented, however, nothing is known about how the peristome develops. Since the peristome forms within still-closed pitcher buds, studying this surface requires the termination and dissection of growing buds. To address this, one key aim of this study was to link the outer macro-development of the bud to the inner micro-development of the peristome. From this, a framework to predict peristome developmental stage, without the need to destroy a developing bud, was created. I hypothesise that to produce this novel surface, Nepenthes employ common epidermal patterning processes and utilise them in a unique way. I predict that the internal development of the peristome can be reliably linked to the external development of the bud, using outer morphological markers. Here the timelines of internal and external development are characterised and linked for the first time. We confirm that the peristome develops via a series of widespread epidermal patterning processes e.g. papillate formation, cell outgrowth, and cell elongation. These events are co-opted in a novel way during peristome development. This research provides an exciting new insight into the development of a highly complex, inspiring, and biomimetically useful plant surface.

The tomato-potato psyllid (TPP), Bactericera cockerelli (Sulc), is a pest to solanaceous crops (e.g. potato, tomato, peppers, and eggplant) and is associated with economically important plant diseases. Subsequently, chemical control is the preferred management option. However, chemical reliance is associated with a host of issues. The development of biological control methods is vital to implementing Integrated Pest Management (IPM) programs as an alternative to broad-spectrum insecticide usage. The predatory bug Orius vicinus (Ribaut) is a potential biological control agent that is capable of consuming all nymphal life stages of TPP. In order to be a commercially viable management option, potential biological control agents of TPP have to cope with the different morphological plant features of the pest’s wide range of host plants. Tomato and capsicum plant surfaces were selected as the experimental surfaces for my thesis because they differ significantly in their substrate morphology. Tomato plant surfaces can be a hostile environment for potential biological control agents due to the negative effect tomato trichomes have on their foraging performance. Alternatively, because capsicum plant surfaces are virtually void of trichomes they appear to be more suitable for effective biological control agent deployment. I exposed the predatory bug to a variety of TPP nymph densities (10, 20, 30 and 40 individuals) in order to determine the functional response of O. vicinus. Furthermore, the predatory bug was exposed to all five TPP nymphal stages simultaneously. The predatory performance of O. vicinus was also assessed on experimental arenas varying in complexity (leaflet vs. small plant environments). The functional response was determined to be Type II on both plant surfaces. Nymph consumption at higher prey densities (30 and 40 nymphs) was significantly greater on capsicum than on tomato. Nymph consumption at lower prey densities (10 and 20 nymphs) was only significantly

In this study we evaluated the leaf surface properties of maize populations native to different water availability environments. Leaf surface topography, wettability and gas exchange performance of five maize populations from the Sahara desert, dry (south) and humid (north-western) areas of Spain were analysed. Differences in wettability, stomatal and trichome densities, surface free energy and solubility parameter values were recorded between populations and leaf sides. Leaves from the humid Spanish population with special regard to the abaxial side, were less wettable and less susceptible to polar interactions. The higher wettability and hydrophilicity of Sahara populations with emphasis on the abaxial leaf surfaces, may favour dew deposition and foliar water absorption, hence improving water use efficiency under extremely dry conditions. Compared to the other Saharan populations, the dwarf one had a higher photosynthesis rate suggesting that dwarfism may be a strategy for improving plant tolerance to arid conditions. The results obtained for different maize populations suggest that leaf surfaces may vary in response to drought, but further studies will be required to examine the potential relationship between leaf surface properties and plant stress tolerance.

The application of agrochemical sprays to the aerial parts of crop plants is an important agricultural practice world-wide. While variable effectiveness is often seen in response to foliar treatments, there is abundant evidence showing the beneficial effect of foliar fertilizers in terms of improving the metabolism, quality, and yields of crops. This mini-review is focused on the major bottlenecks associated with the uptake and translocation of foliar-applied nutrient solutions. A better understanding of the complex scenario surrounding the ultimate delivery of foliar-applied nutrients to sink cells and organs is essential for improving the effectiveness and performance of foliar fertilizers.