Browsing by Author "Mehring, Grant Harry"

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    Determining Optimum Seeding Rates for Diverse Hard Red Spring Wheat (Triticum Aestivum L.) Cultivars
    (North Dakota State University, 2016) Mehring, Grant Harry
    Seeding rate for maximum grain yield can differ for diverse hard red spring wheat (HRSW) (Triticum aestivum L.) cultivars and can be derived from a seeding rate response curve. Six groups of HRSW cultivars with combinations of Rht-B, Rht-D, and Ppd-D with two cultivars per group were planted in 2013-2015 at five seeding rates in 23 trials throughout Minnesota (MN) and eastern North Dakota (ND), USA. Seeding rates ranged from 1.59 – 5.55 million seeds ha-1. Planting dates represented optimum and delayed seeding dates. Agronomic measurements for plant height, lodging, stems per plant, protein, and yield were obtained. Stand loss measurements, defined as the amount of viable seeds that did not become established plants, ranged from 11-19% across seeding rates most commonly planted in the region. There was a seeding rate by cultivar interaction for plant height, protein, lodging, stems plant-1, and yield. As seeding rate increased stems per plant consistently decreased and there were large differences in tillering capacity between cultivars. Increased seeding rate caused increased lodging for those cultivars with a capacity to lodge. Seeding rate for maximum yield of the cultivars differed. Combined over all cultivars, the seeding rate for maximum yield increased as the average yield of an environment decreased. An analysis of covariance (ANCOVA) predictive model was built for yield and tillering. The model for yield across all environments was not predictive with a validation R2 of 0.01. However, when only the bottom six yielding environments out of the total 21 environments were used to build a yield model the predictions were more accurate with a validation R2 of 0.44. The model built and validated for tillering was predictive for the validation environments with an R2 of 0.71 for validation environments. Seeding rate trials continue to be useful for producers making seeding rate decisions for a range of agronomic reasons. Additionally, using regression predictions and separate training and validation datasets to predict yield and tillering with HRSW, genetic and geographic predictors show promise for recommending seeding rates for future environments.
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    Weed Control with Cover Crops in Potato (Solanum Tuberosum L.)
    (North Dakota State University, 2013) Mehring, Grant Harry
    Field experiments were conducted near Oakes and Fargo, North Dakota from 2009-2010, and repeated near Carrington, North Dakota from 2010-2011, to evaluate weed control in both irrigated and non-irrigated potato production as influenced by cover crops and cover crop termination methods. Cover crop treatments at Oakes and Fargo were no cover crop, triticale, rye, turnip/radish, and rye/canola. Cover crop treatments at Carrington were no cover crop, triticale, rye, hairy vetch, and rye/hairy vetch. Termination treatments for the cover crops were roller-crimp, disk-till, roto-till, and herbicide. Cover crop residue was mostly sufficient for weed control at all locations. However, after two cultivations cover crops controlled weeds similar to no cover crop. Cover crop had no effect on potato marketable yield at the two locations. Results support the consideration of cover crops for potato production as a means of additional early-season weed control, especially when non-chemical weed control methods are desired.