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Document Type

Dissertation - University Access Only

Award Date


Degree Name

Doctor of Philosophy (PhD)


Plant Science

First Advisor

Vance N. Owens


Optimizing the application of N fertilization and proper N management is an important factor for biomass production systems. However, recent increases in N fertilizer cost and the negative environmental impacts of chemical fertilizers have prompted the use of legumes as a source of N in sustainable biomass production systems. Overall objects for this study were to determine 1) if different urea nitrogen rates, planting spacing and growth years affected prairie cordgrass biomass (Spartina pectinata Link.) yield and yield components in prairie cordgrass monoculture, and N fertilizer replacement value of kura clover (Trifolium ambiguum Bieb.) in prairie cordgrass and kura clover mixture compared to monoculture prairie; 2) examine how kura clover and different urea N rates, plant spacing and growth years affected mineral compositions, cell wall composition, and theoretical ethanol yield (TEY) of prairie cordgrass/kura clover mixtures and prairie cordgrass monocultures; 3) determine kura clover root exudate flavonoids composition and role of flavonoids in kura clover nodule development. Yields varied by location and ranged from 6.4 to 16.6 Mg ha-1. Urea N treatments, year, spacing and a year x spacing interaction affected prairie cordgrass production at all locations. Yield of prairie cordgrass with 0 N was equal to or less than the yield of prairie cordgrass grown with kura clover at all locations the first two years after establishment; however,there was a N value associated with prairie cordgrass grown with kura clover in the third year. Fertilizer nitrogen replacement value of kura clover ranged from 25 to 82 Kg N ha-1 in the third year. Nitrogen application significantly affected mineral composition, cell wall composition and TEY at most locations. Prairie cordgrass and kura clover mixtures had less desirable mineral concentrations, cell wall compositions and theoretical ethanol yield (TEY) than prairie cordgrass monocultures. Variability in TEY ha-1 was much greater than TEY Mg-1. Daidzin type flavonoids were the most abundant in kura clover roots. Silencing of IFS led to roots deficient for daidzin, genistein and their derivatives. On the other hand, silencing of CHS led to roots deficient for all flavonoid compounds. Silencing of IFS had no effect on nodulation while silencing of CHS significantly reduced nodulation compared with control vector roots. This observation indicated that isoflavonoids do not play a key role in kura clover nodulation despite being the most abundant root flavonoids; however other flavonoids play an important role in kura clover nodulation.

Library of Congress Subject Headings

Kura clover
Energy crops
Biomass energy


Includes bibliographical references (pages 71-76)



Number of Pages



South Dakota State University


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