Graduate Thesis Or Dissertation
 

Possible association of grain protein content, harvest index and biological yield in winter wheat populations

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/pc289n520

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  • A negative relation between grain protein content and grain yield is frequently observed in wheat (Triticum aestivum L. em Thell) i.e. as grain yield increases, grain protein decreases. It has been suggested that the inverse relation between grain yield and protein is in part the result of developing high yielding semi-dwarf wheat cultivars with an increased harvest index. This investigation was undertaken to determine the nature of the possible association of grain yield and protein content as influenced by harvest index, biological yield, plant height and kernel weight in winter wheat populations grown in Oregon. Progenies derived from three crosses of winter wheat were solid-planted in two environments during two seasons. Phenotypic correlations showed a moderate negative association of grain protein content with both grain yield and harvest index. The magnitude of the genetic correlations suggested the presence of genetic relationships among these traits. Selection for harvest index among these crosses could cause a correlated reduction of grain protein content. To investigate if the relationships between grain protein content and selected plant growth traits were similar when grown under space-planted and solid seeded stands, progenies of two winter wheat crosses were evaluated during two seasons. Performance for grain yield and grain protein content was different under contrasting sowing densities as values were not correlated between sowing densities. This indicates the need to evaluate these traits in solid-seeded stands. Harvest index, as well as plant height and heading date, could be effectively selected under space-planted or solid seeded conditions. Associations among traits were reliably estimated in space-planted stands. To evaluate the effect on grain protein content when grain yield and harvest index are modified, the plant growth regulator Paclobutrazol was applied to selected winter wheat genotypes under field and greenhouse conditions. Paclobutrazol increased grain yield and harvest index values of all genotypes in the greenhouse, while only some genotypes improved these traits under field conditions. Grain protein content, however, remained unchanged. Higher grain yields were obtained in both greenhouse and field experiments.
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