Effects of Density, Nitrogen and Photoperiod on Morphology and Biomass Allocation in Alliaria Petiolata

Abstract

Traits associated with carbon acquisition may exhibit plastic responses to different density, nitrogen and photoperiod treatments. In this experiment, petiole elongation and shifts in biomass allocation were examined in Alliaria petiolata (also known as garlic mustard) grown in high and low densities, given moderate and high nitrogen fertilizer treatments, and subjected to either short day or long day photoperiod treatments. The results indicate that rosette plants exhibit density-dependent elongation and an increased shift to above ground plant parts in high density. Fibrous root biomass was reduced in high density and we suggest that this observed reduction is not a cost of elongation but is itself adaptive. Although garlic mustard is considered a nitrophile, our results yield few significant nitrogen effects. Photoperiod treatments affected plant size, elongation and biomass allocation patterns, but depend on what density plants were grown. Low density plants responded more conservatively to short day photoperiod, producing shorter petioles and allocating less resources to above ground parts, suggesting that the difference in microclimate between low and high density stands may play an important role in these plants’ response to spatial and temporal cues.