Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2001. / Härtill 4 uppsatser.

Thesis (Ph.D.)--Aberdeen University, 2008. / Title from web page (viewed on Apr. 14, 2009). Includes bibliographical references.

Studies were carried out to evaluate the repellent properties of the seeds of alligator pepper, <i>Aframomum melegueta </i>and Black pepper, <i>Piper guineense, </i>and ginger, <i>Zingiber officinale </i>rhizomes against <i>S. zeamais</i>. In 4-way olfactometry bioassays, <i>S. zeamais</i> adults showed strong attraction to maize and wheat seed volatiles but were significantly repelled by odours emanating from the seeds of <i>A. melegueta</i>, <i>P. guineense</i> and <i>Z. officinale</i> rhizomes. In field trials crushed <i>A. melegueta </i>seeds and <i>Z. officinale </i>rhizomes, significantly repelled <i>S. zeamais</i> from traditional maize granaries with treated maize cobs giving higher germination than untreated cobs. Laboratory reproductive potential studies showed that <i>A. melegueta </i>and <i>Z. officinale </i>powders caused significant adult mortality and reproductive potential deterrence against <i>S. zeamais</i> resulting in a reduction in F₁ progeny emergence. Olfactometer bioassays also confirmed that vacuum distilled <i>A. melegueta</i> and <i>Z. officinale </i>extracts and oleoresins were repellent towards adult <i>S. zeamais</i> when tested alone, and in combination with maize grains. Bioassay-guided liquid chromatography of the distillates showed that fractions containing polar compounds accounted for the repellent activity. Coupled gas chromatography-mass spectrometry (GC-MS), followed by GC peak enhancement and enantioselective GC using authentic compounds, identified 3 major compounds in the behaviourally active <i><span style='text-transform:uppercase'>A. melegueta </i>fraction to be (<i>S)</i>-2-heptanol, (<i>S)</i>-2-heptyl acetate and (<i>R)</i>-linalool in the ratio 1:6:3. <i>Z. officinale</i> had 1,8-cineole, neral and geranial in the ratio of 5.48:1:2.13. The identification of these behaviourally active compounds provides a scientific basis for the observed repellent properties of <i><span style='text-transform:uppercase'>A. melegueta </i>and <i>Z. officinale </i>extracts, and demonstrates the potential for their development in stored-product protection at the small-scale level in Africa.

Thesis (M.Sc. (Plant protection )) --University of Limpopo, 2011 / Monsonia burkeana is widely used as a decoction for plant protection in South Africa. However, the accumulative capabilities (ACs) for essential nutrient elements and phenolic-antioxidant relationship in its organs are not documented. A study was conducted to determine whether: (1) the ACs for nutrient elements in fruit, leaf, stem and root of M. Burkeana were similar, (2) total phenolic and antioxidant contents in fruit, leaf, stem and root of M. burkeana were distributed equally, and (3) phenolic levels have an effect on accumulation of antioxidants in the four organs. Ten plants per plot, with three replicates, were harvested whole, oven-dried and separated into the four organs and then quantified for the above enlisted variables. The ACs for essential nutrient elements differed among the four organs. Generally, reproductive organs and leaves had high ACs for macro-nutrients, whereas roots had high ACs for micro-nutrients. Similarly, reproductive organs and leaves were good sources of phenolic and antioxidant compounds. Saturation factors in various organs of M. burkeana suggested that more than 90% of antioxidants were derivatives of the phenolic compounds. Optimum levels of antioxidant activities were attained at 5.39, 5.49, 4.36 and 4.13 mg/ 100 g of phenolic content in fruit, leaf, stem and root, respectively. Consequently, M. burkeana organs have the potential to provide fertiliser effect on crops, and both phenolics and antioxidants required as active ingredients for sprays used in plant protection. / the National Research Foundation,the National Department of Agriculture,Forestry and Fisheries,the National Department of Science and Technology

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