No description available.

No description available.

No description available.

Sorghum (Sorghum bicolor [L.] Moench) is fifth among the major cereal crops in the world in terms of production area and total production. Grain sorghum can be successfully produced in a wide range of environments, its productivity is severely limited by pathogens, insects and abiotic stresses. One of these pathogens is Claviceps africana Frederickson Mantle & de Milliano, commonly known as ergot. As is the case with many sorghum diseases, the best long term approach to control ergot may be the use of genetic resistance. There is limited information about resistance to C. africana in sorghum, and the reported resistance in most lines is fertility-based. Dahlberg (1999) first reported the line IS8525 to have the most tolerance to ergot of any of the accessions screened in Puerto Rico. The specific objectives of this research are: (1) to confirm the presence of C. africana resistance in IS8525 germplasm, (2) to determine if the resistance in IS8525 is pollen mediated or ovule based, and (3) to determine if the resistance in IS8525 is heritable and stable across environments. Ergot vulnerability ratings were determined for two recombinant inbred line populations, IS8525D and IS8525J, in four locations during 2001. Also, ergot vulnerability ratings were evaluated in four test-cross populations (using as testers A3Tx623 and A3Tx623) in two locations. Evaluations of the original parents indicate that ergot tolerance in IS8525D parent was consistently better than that in IS8525J parent. As expected, neither parent provided complete resistance. The IS8525J recombinant inbred line population showed significantly more ergot susceptibility than the IS8525D recombinant inbred line population and this trend was consistent across environments. Variation for ergot vulnerability amo ng recombinant inbred lines for both populations was detected, but the amount of variability was environment dependent. In the testcross hybrids, all four populations were susceptible to ergot, primarily due to male sterility in the hybrids, confirming that the tolerance shown in IS8525 germplasm is mostly pollen mediated. However, a greater level of tolerance in the IS8525 hybrid checks confirmed the reports of tolerance by Dahlberg et al. (1998) and Reed et al. (2002).

Climate change, shrinking arable land, burgeoning population and malnutrition have made all aspects of crop improvement a critical issue. Of these, nutritional quality of crops is perhaps one of the most important aspects. Most cereals consumed in marginal agro-ecological zones of Africa, for example sorghum and maize are impoverished nutritionally. Given therefore the sole reliance on and the levels of consumption per day of such staples (up to 450 g/day), it is clear that most people cannot obtain the recommended daily allowance (RDA) for many nutrients including fibre, edible oil, protein, vitamins and mineral elements. In this thesis, the development of a sorghum mutant population using gamma irradiation and the subsequent employment of various analytical techniques to unravel multiple mutant traits with a significant positive impact on nutritional enhancement in sorghum is described. Protein analysis revealed a mutant designated SY accumulating (at the time) the highest ever reported amount of free lysine (21.6 g/100g) and other essential amino acids and that these changes were associated with induced protein polymorphisms. Adaptation of proton induced x-ray emission (PIXE) for the spatial profiling of the distribution of 9 elements in sorghum seed tissue allowed for the discovery of mutants with variations in the concentrations and distribution of these elements. The observed changes included enhanced or diminished accumulation of elements in preferential accumulation tissues and entire changes in cellular localisation. The locations within a cell and the quantities of an element are often critical determinants of bioavailability. The accumulation of multiple mutations affecting multiple nutritional traits in individual mutant sorghum clearly indicates the versatility of gamma irradiation induced mutations in addressing multiple nutritional challenges of sorghum. This desirable phenomenon was further demonstrated by electron microscopic analysis of starch granules and protein bodies across the mutants. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed changes in size, shape, ultra-structure and packed cell volumes of seed protein- and starch bodies. Induced mutation had a major effect on the protein body structure which in turn resulted in changes to protein digestibility. High digestibility mutants had a unique dense protein matrix with dark inclusions. However, improved protein quality traits were also associated with floury endosperm texture. Since endosperm texture is an important grain quality attribute and plays a major agronomic role, it is important to ensure that future work focuses on improving grain hardness. The mutants obtained in this study are therefore a valuable germplasm source for sorghum breeding and present real opportunities for addressing nutritional challenges of sorghum. / Ph.D. University of KwaZulu-Natal, Durban 2013.

Sorghum is considered to be of African origin and subsequently spread to most countries in tropical and subtropical regions. Sorghum has outstanding resistance against drought conditions. Grain and fodder from sorghum plants have been used for man's and animals' consumption respectively for many decades. Experiments were conducted on Yasothon soil series (Oxic Paleustults) in Northeast Thailand, this is considered a poor soil. Growth parameters of sorghum were affected most by nitrogen chemical fertiliser followed by potassium chemical fertiliser. An increase in nitrogen level increased growth parameters and seed yields/ha of the sorghum plants whilst an increase in potassium also increased growth parameters and seed yields but to a lesser extent. High application rates of both nitrogen and potassium were required to achieve high total dry weights and seed yields/ha. Fermented cattle manure significantly increased growth parameters of the sorghum plants and soil properties. were also improved by cattle manure. Total dry weights and seed yields/ha were affected most by seasons and treatments whilst seasons x treatments had highly significant effects on seed yields/ha but not total dry weights/ha. In terms of economic viewpoint, optimum application rates for nitrogen at a range of 300-450 kg N/ha and 100 kg K20/ha for potassium plus 40 tonnes/ha of fermented cattle manure were the recommended rates for optimum above ground total dry weight (15,940-26,282 kg/ha) and seed yield (5,047- 6,374 kg/ha) of IS 23585 forage sorghum cultivar on Yasothon soil series. An increase in nitrogen fertiliser application increased estimated crude protein (CP) of the sorghum plants whilst potassium did not. Both nitrogen and potassium had no Significant effects on acid detergent fibre (ADF), neutral detergent fibre (NDF), and dry matter degradability (DMO). However, seasons had significant effects on CP, NDF, ADF, DMD and brix values. Treatments also had significant effects on all components except DMD, and brix values. Seasons x treatments had significant effects on all components except CP and brix values.

No description available.

Thesis (Ph.D.)(Food Science))--University of Pretoria, 2008. / Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (M. Sc.(Agric.))(Food Science)--University of Pretoria, 2008. / Includes summary. Includes bibliographical references). Available on the Internet via the World Wide Web.

Thesis (Ph. D.)--University of Hong Kong, 2007. / Title proper from title frame. Also available in printed format.