279-17
Evaluation of Natural Abundance of δ15N Signatures for Potential Nitrogen-Fixation in Three Perennial Feedstock Grasses.

Tuesday, November 5, 2013: 12:15 PM
Marriott Tampa Waterside, Grand Ballroom G, Second Level

Jayani J Wewalwela1, Mark A. Williams2 and Janet R Donaldson1, (1)Biological Sciences, Mississippi State University, Starkville, MS
(2)Virginia Tech, Blacksburg, VA
Associative nitrogen fixing (ANF) microorganisms in feedstock grasses enhance the soil nitrogen pool in order to supply nitrogen required under natural field conditions. Perennial feedstock grass can yield large quantities of lignocellulose useful for the production of biofuels. Such grasses include Miscanthus x giganteus (Mxg), Pancium virgatum (switchgrass), and energycane (US 02-147). Endophytic and free-living associative nitrogen fixing bacteria often support these grasses to meet the required nitrogen needs of the plants. The objective of this study was to measure the potential for associative nitrogen fixation in these three feedstock grasses over a three-year field study to determine their ability to accumulate nitrogen in the soil. Total above ground biomass, δ 15N in soil collected at two depths (0-10 and 10-30 cm), and δ 15N in roots and shoots were analyzed to determine the collective nitrogen contribution to the soil for each grass. The soil δ 15N values collected at the 0-10 cm depth significantly decreased in energycane in comparison to switchgrass and giant miscanthus. Moreover, the δ 15N in roots of energycane were reduced drastically, suggesting endophytic nitrogen fixating microorganisms contribute to the increased plant nitrogen pool. Reductions were also evident with switchgrass and giant miscanthus roots. All three energy grasses had lower δ 15N than the annual Sorghum (M81-E) and soil alone. These results indicate that energycane associated nitrogen fixers have the highest potential to fix nitrogen in soil under natural field condition.
See more from this Division: SSSA Division: Soil Fertility & Plant Nutrition
See more from this Session: Soil Fertility and Plant Nutrition Division and Nutrient Management and Soil and Plant Analysis Division Graduate Student Oral Competition - Nitrogen Management (PhD degree)

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