http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
relationship of germination parameters to field adaptation and heat stress tolerance in Sorghum bicolor (L.) Moench
xiii, 152 leaves : illustrations ; 29 cm
Four separate but related experiments were conducted in 1981 to 1983 in an effort to expand on and clarify previous research results relating to the base germination temperature of Sorghum bicolor (L.) Moench and that parameter's relationship to adaptation. A second germination parameter was examined to determine if field heat stress tolerance could be screened for by germination tests. A new technique and corresponding statistical model were developed to measure base germination temperature. A second parameter was established which measured sorghum genotypes' ability to withstand very high temperatures (50(DEGREES)C) during germination. These two germination parameters were than used to select F(,4) lines of two R and two B-line crosses for field evaluation at 12 locations extending from Puerto Rico to Nebraska. The agronomic and climatic data from these locations were then used to test the efficacy of the two germination parameters established in the first experiment for predicting adaptation in the first case and field heat tolerance in the second. F(,4) genotypes with high base germination temperatures were earlier to mature, taller, and higher yielding than their sibling lines with low base germination temperatures. These effects were barely discernible in Puerto Rico, but became more obvious in locations which were more temperate in nature. The heat stress tolerance (HST) index was negatively correlated to yield at the hottest locations. A third experiment determined if divergent selection for base germination temperature (G50) and heat stress tolerance (HST) would result in genetic gain in the direction of selection. Only in the case of selection for high HST was divergent selection able to separate significantly F(,4) plants and their selected F(,4) progenies. Low numbers of pairs to test confounded the G50 experiments, as less than 6 F(,5) plants produced sufficient F(,4) seed for testing in either G50 selection scheme. The last experiment was designed to determine if the environment of the maternal plant during seed maturation affected the germination parameters discussed above. Seed produced at College Station under higher temperatures and longer daylengths during seed maturation had significantly higher G50 values than seed produced at three other locations with lower temperatures and shorter daylengths. . . . (Author's abstract exceeds stipulated maximum length. Discontinued here with permission of author.) UMI
Ph. D. in Philosophy Texas A & M University 1983
Includes bibliographical references (leaves 105-112).