Graduate Thesis Or Dissertation

 

Development of oven and Karl Fischer techniques for moisture testing of grass seeds Public Deposited

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/p2677044p

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  • Seed moisture is a primary factor influencing seed quality during harvesting, storage, and marketing of grass seed. However, the Association of Official Seed Analysts' Rules for Testing Seeds do not contain methods for moisture testing. The oven methods in use by seed testing laboratories in the U.S. are diverse and many produce erroneous results. The International Seed Testing Association Rules for Seed Testing contain methods for 95 kinds of seeds, but many of the methods are empirical in nature and lacking in accuracy. The objective of this research was to develop accurate oven moisture testing methods for seeds of temperate grass species. The test variables investigated were oven temperature, time of drying, grinding the seed, and original moisture level of the seed. Chi-square analysis was used to determine if the results of the oven methods were within +̲ 0.5% of those obtained by the Karl Fischer reference method. The species included were perennial ryegrass (Lolium perenne L.), orchardgrass (Dactylis glomerata L.), bentgrass (Agrostis tenuis L.), Kentucky bluegrass (Poa pratensis Huds.), tall fescue (Festuca arundinacea Schreb.), and red fescue (Festuca rubra L.). Drying to constant weight at temperatures of 90, 100, and 105°C gave moisture percentages lower than the true value. Drying periods of 6 h or less at 130°C gave moisture percentages in agreement with Karl Fischer results. Ground and whole seed gave similar moisture percentages after drying to constant weight, but moisture was removed more rapidly from ground seeds. The required drying time for greatest accuracy depended on the original moisture content of the seed. Moisture was removed most rapidly from the highest moisture seed; thus, it is not possible to select one drying period that will provide the same degree of accuracy on seed with different moisture levels. Seed moisture tests on these six temperate-climate grass species should be conducted on whole seeds at 130°C. The drying periods should be 3 h for perennial ryegrass, Kentucky bluegrass, tall fescue, and red fescue, 1.5 h for orchardgrass, and 1 h for bentgrass.
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