Higher grain yield is a key objective in barley (Hordeum vulgare. L) breeding. Despite extensive research on the genetics of yield and its components, selection for yield per se is still the most extensively employed because of negative relationships among components, modest correlations between yield and any particular component, and the additional resources required for measuring the components. The development of quantitative trait locus (QTL) detection procedures allows for an alternative approach to this issue. The objective of this investigation was to determine the biological basis of observed grain yield QTLs, with particular reference to yield components and yield-related traits. Yield and yield component traits were assessed in a population of spring barley doubled haploids from a cross of 'Steptoe' x 'Morex'. The scope of inference of the experiment was broadened by using reference QTL data sets from the multiple environment assessment of the same population. Both positive and negative relationships among yield, component, and related trait QTLs were observed. The QTL data indicate that indirect selection for yield via yield components would be ineffective. The yield QTL effects in this germplasm were largely attributable to lodging and basal internode length. Localization and interpretation of yield QTLs may be useful for studying orthologous gene expression in other germplasm and in developing multiple character selection strategies. / Graduation date: 1994

Thesis (Ph. D.)--University of Wisconsin--Madison, 1943. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 65-70).

No description available.

Amines formed by biosynthesis in germinated barley have been suggested as precursors for N-nitrosodimethylamine (NDMA) in barley malt dried by direct-fired kilning. This hypothesis was verified by germinating raw barley and exposing the resulting malt roots and clean malt to nitrous acid. Quantitation of the NDMA formed indicated that malt roots contained relatively large amounts of NDMA precursor which could only have been formed as a result of germination. The clean malt also contained NDMA precursor, but the amount of precursor in clean malt was only slightly higher than the level of precursor already present in raw barley. The two tertiary amine alkaloids, hordenine and gramine, which are biosynthesized in malt during germination were subjected to nitrosation. Nitrosation of both amines at 65° (pH 4.4 or pH 6.4) resulted in NDMA formation. Gramine was highly susceptible to nitrosation to yield NDMA. At 24° in dilute acetic acid (pH 3.4), the initial rate of nitrosation of gramine to yield NDMA was nearly equal to the initial rate of NDMA formation from dimethylamine. The ratio of initial rates of formation of NDMA from gramine and trimethylamine was 6250:1. At 23°, the ratio of initial rates of formation of NDMA from gramine and hordenine was 5200:1. N-Methyltyramine and N-methyl-S-aminomethylindole, the immediate biosynthetic precursors of hordenine and gramine, were synthesized. Nitrosation of N-methyltyramine yielded p-hydroxy-N-nitroso-N-methyl- 2-phenylethylamine as the major reaction product and p-hydroxy-m-nitro- N-nitroso-N-methyl-2-phenylethylamine as the minor product. Nitrosation of N-methyl-3-aminomethylindole yielded N-nitroso-N-methyl-3- aminomethylindole as the minor reaction product; the major product was a dinitroso compound identified as N¹-nitroso-N-nitroso-N-methyl-3- aminomethylindole. Investigation of the products of hordenine nitrosation at 65° (pH 4.4) indicated the formation of NDMA and p-hydroxy-m-nitro-N-nitroso- N-methyl-2-phenylethyl amine; p-hydroxy-N-nitroso-N-methyl-2- phenylethylamine was not observed as a product of hordenine nitrosation at 65°. NDMA appeared to be the major nitrosamine formed from hordenine. The rapid reaction of gramine with nitrous acid and investigation of the gramine nitrosation reaction products both indicated that gramine did not undergo nitrosation by the expected mechanism of nitrosative dealkylation. A new mechanism is proposed to explain the rapid reaction of gramine with nitrous acid and to account for the fact that NDMA was the only N-nitrosamine formed during the nitrosation of gramine. / Graduation date: 1983

No description available.

Thesis (MTech (Horticulture))--Cape Peninsula University of Technology, 2018. / This study evaluated the effects of 5 different soaking treatments in conjunction with 5 varying irrigation intervals on the germination, growth and nutritional values of seed of Hordeum vulgare Sv13. The 5 different soaking times consisted of 1, 3, 8, 16 and 24 hours. The barley seed was first cleaned and then placed in a vessel containing 500 ml of distilled water with a 20 % solution of sodium hypochlorite (bleach) at room temperature. Thereafter the pre-soaked seeds were transferred to a perforated container, containing no medium and placed into a growing chamber equipped with drip irrigation. The seed was then irrigated with 1245 ml of water at 5 different intervals namely every 2, 4, 8 10 and 12 hours. The temperature of the hydroponic growing room was kept at a constant 23 °C using a hotoperiod of 16-hour day/ 8-hour darkness. The seed was allowed to germinate and grow for a period of 8 days before being harvested. The objectives of this study were to determine the most beneficial combination of soaking treatment in conjunction with the most beneficial irrigation interval on the germination rate of the seed allowing for radicle emergence and coleoptile production. It was also used to determine which combination of treatments was most beneficial to the growth and nutritional values of the seed post-harvest. Another objective was to ascertain the shortest soaking time for application in a small-scale, hydroponic growing unit as well as the frequency of irrigation required to grow seedlings, thereby determining the amount of water required to produce a seedling mat for a small-scale, subsistence farmer, with the emphasis being on water reduction. Each treatment was replicated 10 times and consisted of 500 grams of seed, which when placed into its container measured 2 centimetres in depth, totalling 25 treatments in all. Germination was measured by observing radicle emergence in the first 2 days of the growing period first after a 24-hour cycle and again after 48 hours. The numbers of leaves present at harvest after an 8-day growing period were also counted to determine germination rate of the seeds. Growth was determined by average leaf height as well as the tallest leaf on day 8 of the growing cycle. Root mat expansion was also measured, post-harvest, which was compared to the initial 2 cm planting depth of seed. Wet and dry weights of the plant material were measured post-harvest. Samples of the harvested material were also sent for nitrogen and protein analysis. It was discovered that most of the results favoured a shorter soaking time and an increase in irrigation frequency, bar a few exceptions. Most favoured a pre-soaking time of only 1 hour together with an irrigation frequency of between 2 and 4 hours. This shows that small-scale farmers would be able to reduce the time spent on soaking of their seed. Although the frequency of the irrigation interval remained high further testing would be required to determine if the amount of water applied at each irrigation interval could be reduced and still produce favourable results. It would also remain to be seen if no irrigation during the 8-hour dark photoperiod would have any negative impact on germination, growth and nutritional values of the seedlings.

On title page "B" is superscript. Bibliography: leaves 112-135. The primary aims of the work described in this thesis were to isolate and characterize the cDNAs that correspond to the two B-glucan exohydrolases designated isoenzyme ExoI and isoenzyme ExoII. (abstract)

"July 2003" / Includes bibliographical references (leaves 150-179) / xiv, 179 leaves : ill., plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, 2003

"June 2004" / Bibliography: leaves 143-164. / xviii, 165 leaves : ill. (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / "This thesis describes the first study of linkage disequilibrium (LD) in an inbreeding crop species, specifically Hordeum vulgare." --p. 1. / Thesis (Ph.D.)--University of Adelaide, School of Agriculture and Wine, Discipline of Plant and Pest Science, 2005?

No description available.