Theses and Dissertations at Montana State University (MSU)
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Item Genetic dissection of stay-green and other traits related to dry land spring wheat performance(Montana State University - Bozeman, College of Agriculture, 2016) Acharya, Roshan Kumar; Chairperson, Graduate Committee: Jamie ShermanSpring wheat production in the upper Great Plains is at risk due to increased occurrence of low moisture and high temperatures during grain-fill. Wheat yield is impacted by several often counteracting traits, including seed number per head, seed weight and number of productive tillers. A variety of morphological and phenological plant characteristics impact performance in conditions of low moisture and high temperatures during grain-fill. In this study, we dissect traits associated with grain yield using a recombinant inbred line (RIL) mapping population derived from parents with contrasting phenotypes for several yield and drought related traits. Importantly, differences in quantitative trait loci (QTL) for yield and yield components were observed in the RIL between rain-fed and irrigated environments. We report important QTLs associated with yield and drought stress in spring wheat, with the long term goal of identifying traits useful to molecular breeding programs for the creation of lines better adapted to our changing environments. We also confirmed six grain-fill QTLs in association mapping (AM) panel which were identified by using this RIL population.Item Impact of a QTL for plasticity of productive tiller number on yield and yield competitive ability of spring wheat(Montana State University - Bozeman, College of Agriculture, 2015) Nasseer, Afaf Mahdee; Chairperson, Graduate Committee: Luther E. TalbertHeat and drought stress are important limitations on wheat growth and reproduction. Therefore, there is a need to understand mechanisms that enable wheat plant adapted to heat and drought stress, and maintain plant growth, development, and productivity during stress periods. One of the most important plasticity traits in wheat is productive tiller number (PTN). This thesis reports two studies. The goal of the first study was to test the impact of a previously identified allele for high productive tiller number on yield and yield components, agronomics, and seed quality traits, in a set of near isogenic lines developed in three genetic backgrounds, including the crosses Vida/McNeal, Reeder/Choteau, and Reeder/Hank. Results from nine field locations showed that high productive tiller allele on QTn.mst-6B enhanced early tiller (ETN) formation regardless of the locations. Under favorable conditions, the large number of early tillers transferred into a capacity for high productive tiller number, which may enhance grain yield. Seed number per head and seed weight was affected negatively by the high tiller allele at QTn.mst-6B over all locations, and thus more tillers did not always equate to higher yield. Moreover the high productive tiller allele on QTn.mst-6B associated with high dry weight of roots based on a greenhouse study. The goal for second study was to assess the impact of QTn.mst-6B under different competition levels and levels of available water. Five near-isogenic line (NIL) pairs for two genetic backgrounds (Reader/Choteau, Vida/McNeal) were selected randomly from the three populations of our first study. Three competition levels were imposed on the NIL pairs in replicated experiments. Competition levels were 1) bordered rows representing high competition and limited water, 2) non-bordered rows representing less competition and more available water, and 3) space-planted rows representing no competition and abundant water. The experiment was planted over three locations on 2012 and 2013. The ETN more often developed into PTN in conditions with less competition levels, while did not develop into PTN in conditions of high competition and low water. The high plasticity of PTN was associated with high plasticity in grain yield, and low plasticity of seed weight.Item The effect of simulated drought on stem-stored carbohydrate characteristics in winter wheat(Montana State University - Bozeman, College of Agriculture, 1989) Sabry, Sami Reda SaberItem Drought resistance in barley as related to color and screening tests(Montana State University - Bozeman, College of Agriculture, 1979) Fink, Thomas ConradItem An evaluation of plant drought stress parameters in spring wheat(Montana State University - Bozeman, College of Agriculture, 1987) Touray, Katim SeringeItem The effect of powdery mildew on barley under simulated Mediterranean drought conditions(Montana State University - Bozeman, College of Agriculture, 1989) Zine Elabidine, FatimaItem Inheritance of factors associated with drought tolerance(Montana State University - Bozeman, College of Agriculture, 1977) Kazemi, HamdollahItem A screening technique for evaluating drought resistance of barley (Hordeum vulgare L.) lines(Montana State University - Bozeman, College of Agriculture, 1987) Matin, Mohammad AbdulItem Physiological measurements of drought stress on spring wheat (Triticum aestivum L.)(Montana State University - Bozeman, College of Agriculture, 1988) Elmi, Abdulkadir AhmedItem Preliminary evaluation of selection criteria for drought resistance in alfalfa (Medicago sativa L.)(Montana State University - Bozeman, College of Agriculture, 1981) Carlson, John Robert