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In the lower Rio Grande Valley of south Texas, more than half the nesting groups of Harris's hawks (Parabuteo unicinctus) include at least one auxiliary group member in addition to a breeding pair. To provide further insight into cooperatively breeding raptors, I evaluated sociality in Harris's hawks through the dual benefits framework. I explored the formation, structure, and stability of cooperative group formation across a spatially variable study area, which includes high levels of urbanization and development as well as remote, undisturbed native habitats with low anthropogenic impact. I used color banding, regular censuses of active territories, and a microsatellite relatedness analysis to examine patterns of sociality, including delayed dispersal, the effect of auxiliary group members on reproductive output, parentage of broods, and the relatedness of auxiliaries compared to the nestlings in their territories. I confirmed cooperative polygamy with genetic techniques for the first time in Harris's hawks and found 58% of juvenile hawks delayed dispersal for at least 6 mo. Using the dual benefits framework, I found social associations that formed through delayed dispersal followed predictions for resource-defense benefits, but sociality among mature non-related hawks more closely followed predictions associated with collective action benefits, specifically reproductive output was significantly reduced in undeveloped habitats, presumably due to a less predictable prey-base.

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M.Tech. Agriculture / Sweet peppers (Capsicum annuum L.) are also known as bell peppers or capsicum belonging to the family Solanaceae. The sweet pepper contains various bioactive compounds along with significant amounts of beta-carotene (provitamin-A) and other similar compounds. This technological study was carried out to investigate the influence of photo-selective nets (ChromatiNet™) (red, pearl and yellow), with 40% shading effect, on the morphological parameters (plant height, leaf chlorophyll, stem diameter, leaf area, number of leaves, number of flowers, number of fruit, fruit weight, marketable yield, and pest and disease incidence, the fruit quality parameters (fruit mass, firmness, colour, soluble solids content and titratable acidity) and health promoting compounds (ascorbic acid, lycopene content, β-carotene, total phenols and flavonoids, and antioxidant scavenging activity) of three selected sweet pepper cultivars at harvest maturity stage. The commercially used black net (25% shading) was also included for comparison measures (control). The photosynthetically active radiation, air temperature and relative humidity were monitored throughout the growing period.

Thesis (Ph.D. ( Animal breeding)) --University of Limpopo, 2012 / Refer to document / the Agriculture Research Council