Khasanova, Albina , Thornhill, Megan , Drenovsky, Rebecca .
Impacts of drought on nitrogen resorption of grasses in the Intermountain West.
Nutrient resorption is an important plant nutrient conservation mechanism, whereby plants store mobile nutrients after withdrawing them from senescing leaves. However, it is unclear how factors such as water availability, drought tolerance, and phylogeny influence this process. We hypothesized that drought would negatively impact resorption of nitrogen (N) but that drought tolerant species would be more proficient than drought sensitive species under low water availability. Additionally, we predicted that phylogeny would constrain resorption patterns. Lastly, we hypothesized that there may be a phenological effect on resorption (i.e., differences between summer and fall responses). Our study species included three congener pairs varying in their drought tolerance. The drought-tolerant species were: Agropyron fragile (cultivar Stabilizer), Elymus elymoides (cultivar Rattlesnake GP), and Festuca idahoensis (cultivar Reliable GP); the drought-susceptible species were: Agropyron desertorum (cultivar 'Douglas'), Elymus glaucus (cultivar 'Arlington'), and Festuca roemeri. As hypothesized, we found that senesced leaf nitrogen concentration (a measure of resorption) was higher in droughted plants compared to well-watered individuals (P<0.0001) and that genera varied in their resorption patterns (P<0.0001). Festuca species tended to be poorer at resorbing N than either Agropyron or Elymus, regardless of treatment. Likewise, there was a significant genus*treatment interaction (P<0.0001). Nitrogen concentration in summer-senescing was significantly higher than in fall-senescing leaves (P<0.0001). Together, these data suggest that there are phylogenetic, phenological, and environmental constraints on resorption, which has implications for whole plant nutrient conservation and ecosystem nutrient cycling.
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1 - John Carroll University, Biology Department, 20700 North Park Blvd, University Heights, OH, 44118, USA
Presentation Type: Poster:Posters for Topics
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM