Effect of atmospheric deposition of nitrogen on the fixation and assimilation of nitrogen by wild lupine (Lupinus perennis) in the sand dunes of Lake Michigan
Lauren Avans Purdue University Calumet, Hammond, IN
Faculty Advisor: Young D. Choi
Introduction• Located at the Lake Michigan Dunes• Karner Blue Butterfly is an endangered species• Sole food source of Karner Blue Butterfly• Increase in Nitrogen Deposition recently• I hypothesize that the addition of nitrogen in the soil will increase the biomass production of wild lupine.
Methods
• Germinated in dishes and transplanted• Randomly assigned • NH4NO3 Treatment groups: Water, 7.5g m-2 , 15g m-2
• Harvested 5 months later• Total dry weight biomass and biomass allocation analysis through:– Kruskal-Wallis test– Linear regression analysis
Median total biomass of wild lupine seedlings. Results were significant at p<0.05. n=12. *
represents outliers.
Total dry weight biomass of wild lupine (Lupinus perennis)
Control Low High
Mean ± SE 224 ± 4 mg 198 ± 4 mg 137 ± 3 mg
Median 201 mg 168 mg 130 mg
Median belowground biomass allocation of wild lupine seedlings. Results were
significant at p<0.06. n=12. * represents outliers.
Belowground biomass allocation by wild lupine Control Low High
Mean ± SE 62 ± 5% 60 ± 2% 52 ± 4%Median 66% 63% 53%
Linear Regression Line showing a correlation between the amount of biomass allocated belowground (vertical axis) and the amount of total biomass
(horizontal axis).
Summary
• Contradictory• Population Decline• Total biomass decrease as nitrogen increases • Physiological Drought• Reduction of below ground biomass allocation percent as nitrogen increase
• Below Ground Biomass Allocation Percent Increases as Total Biomass Increases
• Allomeric growth vs. Nitrogen increase
Acknowledgements
This project was funded by Flora Richardson Foundation
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