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Spring barley (Hordeum vulgare L.) is an important cereal crop in Quebec, where it is used as a crop for swine and poultry. Since barley is a better source of energy than protein, a protein supplement must be added to the feed. Consequently, the production of barley with high protein concentration in the grain (GPC) is desirable. Studies on intensive cereal management (ICM) practices in other countries have shown that high yields can be combined with a high GPC. From 1987 to 1990 three field experiments were conducted to evaluate the effects of ICM on the yields and GPC of six-rowed spring barley in Quebec. Our results describe the effects of individual ICM components (N fertilizer application, fungicide, and plant growth regulator) on the development of yield components and on GPC. In general, N had little effect on main stem yield spike$ sp{-1}$ and on tiller spikes m$ sp{-2}$. Possibly, plant density or environmental conditions may have imposed greater limitations on yield rather than N. Nitrogen treatments increased GPC generally by increasing the amount of protein grain$ sp{-1}$. Nitrogen treatments which increased the amount of protein grain$ sp{-1}$ increased the lysine and cyst(e)ine concentrations of the grain but decreased their concentration in the grain protein. The plant growth regulator ethephon increased GPC by increasing the amount of protein grain$ sp{-1}$, by decreasing the nonprotein content grain$ sp{-1}$, or by altering final grain size distribution. Ethephon often had damaging effects on yield. Large genotypic variation was observed for GPC, but could not be related to genotypic differences in N harvest index, total N accumulation, protein yield or post-anthesis N uptake and assimilation. Grain yield was weakly correlated with GPC. Examination of the cultivars grown from 1910 to 1988 showed that increases in grain yield were accompanied by increases in harvest index, total dry matter, and lodging resistance. Plant height was reduced over tim

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Three experiments were carried out to evaluate the applicability of the intensive management system to barley production in Quebec. In the first experiment, the effects of three levels of nitrogen fertilizer and ethephon (Cerone) on the performance of cultivars were tested. The aim of the second experiment was to test the effects of fungicide application and row width. In the third experiment, conventional and intensive management techniques were tested on three soil types. / High levels of nitrogen increased the grain protein content and thus improved the feed quality of spring barley. Application of ethephon reduced plant height but also reduced the number of grains per head. A fungicide by row width interaction resulted in a reduced seed size and weight in the narrow rows. The effects of intensive management on yield were inconsistent and were influenced to a large extent by the prevailing weather and soil conditions.

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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

Bibliography: leaves 187-203. Evaluates critically a number of physiological traits which may be related to drought resistance in cereals and examines the feasibility of using these screening techniques in selecting more drought resistant genotypes of barley for South Australia.

Plant growth regulator(s) (PGR) can be used as lodging inhibitors and/or yield promoters for spring barley (Hordeum vulgare L.). From 1987 to 1990 four field experiments were conducted to monitor barley main-stem apical development and to determine the effects of chlormequat (CCC) and ethephon on the development, physiology and yield of spring barley. Our data provide a description of barley apical development and the general pattern of leaf and spikelet primordium production under field conditions. In general, PGR treatment reduced the apical dominance of dominant sinks allowing the survival and greater development of more subordinate sinks. Early application of either CCC or ethephon retarded development of the main-stem apex from shortly after application to the awn elongation stage and reduced the number of aborted spikelet primordia, thus increasing the potential number of grains per spike and sometimes grain yield. Ethephon applied at ZGS 39 reduced plant height and lodging. Early application (ZGS 30) of ethephon, alone or in combination with CCC increased the number of spikes m$ sp{-2},$ but not grain yield. The number of spike-bearing shoots per unit area or per plant was increased by early PGR treatment, primarily by enhancement of tiller number rather than tiller survival. Early application of CCC or ethephon to spring barley is not justified, and caution must be taken when using ethephon at the currently recommended rate and stage for lodging control. Post-anthesis application of ethephon can efficiently enhance grain fill and yield of spring barley.