Characterization of grain sorghum for physiological and yield traits associated with drought tolerance

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Show simple item record Mutava, Raymond N. 2009-05-18T16:29:19Z 2009-05-18T16:29:19Z 2009-05-18T16:29:19Z
dc.description.abstract Grain sorghum (Sorghum bicolor L. Moench) is the fourth most important cereal crop grown throughout the semi-arid regions of the world. It is a staple food crop in Africa and Asia, while it is an important feed crop in the United States (US). More recently it is increasingly becoming important as a potential bioenergy feedstock crop around the world. The state of Kansas is the largest producer of grain sorghum in the US and contributes 40% of the total production. Drought is one of the major environmental factors limiting sorghum production in the semi-arid regions of the US, Asia and Africa. It is estimated that global crop losses due to drought stress exceed $10 billion annually. In crop production, drought stress can be classified into pre- or post-flowering. Even though the world collections of sorghum contain over 35,000 accessions, the genetic base currently used in breeding programs is very small (about 3%). Thus, it is important to identify diverse breeding lines for crop improvement. The diversity (association) panel consisting of 300 sorghum lines from all over the world was assembled for trait evaluation and association mapping. In this research these lines were grouped into the five major races (Figure 1) and 10 intermediate races of sorghum. The objectives of the research are to: (i) quantify the performance of the diversity panel under field conditions in Kansas, (ii) identify critical physiological traits affected by drought at both pre- and post-flowering stages of sorghum development, (iii) identify the most sensitive stage to drought stress during the reproductive phase of sorghum development and, (iv) test the feasibility of using a chlorophyll fluorescence assay (CVA) as a tool for identifying stay-green lines in grain sorghum during early stages of crop development. Field experiments were conducted in 2006 and 2007 in two locations in Kansas (Manhattan and Hays) under rain fed and irrigated conditions for the association panel. Objectives (iii) and (iv) were achieved with controlled environment experiments conducted in the greenhouse at the agronomy department, Kansas State University in 2006 and 2007. Results showed that there was large genetic variability among and within different races in the diversity panel for growth, physiological traits and yield components. Some genotypes showed yield stability across the different environments that were investigated. Drought significantly decreased seed number and harvest index across genotypes and races. In grain sorghum the period prior to flowering (panicle initiation) was the most sensitive stage to drought stress, in terms of its effect on seed-set, during reproductive development. A cell viability assay showed that there were significant differences in the loss of cell viability between leaf sample of stay green and non-stay green genotypes when leaf samples are collected in the morning and subjected to high respiratory demand. Therefore the chlorophyll fluorescence assay has potential as a tool for stay green trait screening at early stages of growth in grain sorghum. en
dc.description.sponsorship Kansas Grain Sorghum Commission; International Sorghum and Millet Collaborative Research Support Program of USAID; Centre for Sorghum Improvement for their financial support en
dc.language.iso en_US en
dc.publisher Kansas State University en
dc.subject Grain sorghum en
dc.subject Chlorophyll fluorescence assay en
dc.subject Drought tolerance en
dc.subject Yield en
dc.subject Stress en
dc.subject Physiological traits en
dc.title Characterization of grain sorghum for physiological and yield traits associated with drought tolerance en
dc.type Thesis en Master of Science en
dc.description.level Masters en
dc.description.department Department of Agronomy en
dc.description.advisor P. V. Vara Prasad en
dc.subject.umi Agriculture, Agronomy (0285) en 2009 en May en

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