PARENT SESSION
Poster Session 35: Evolutionary Ecology
Thursday, August 11, 5:00 PM - 6:30 PM, Exhibit Hall 220 A-E, Level 2, Palais des congrès de Montréal
Plasticity in relative growth rate and its components following a decrease in nitrogen availability.
Useche, Antonio*,1, Shipley, Bill1, 1 Université de Sherbrooke, Sherbooke, Québec, Canada
ABSTRACT- Nutrient availability varies greatly over short time scales, and this requires plasticity in the morphological and physiological attributes of plants. The objective of this study was to quantify the plasticity in relative growth rate (RGR) and its underlying components following a reduction in nitrogen supply in a set of 14 species with contrasting ecology, and to determine the degree to which different species can buffer their growth rate by coordinated changes in specific leaf area, net assimilation rate, biomass and nitrogen partitioning to leaves vs. roots and root morphology. 44 plants per species in a control series were grown in a constant hydroponic solution over 30 days with 1mM nitrogen and harvested daily from the 7th to 28th days. 44 other plants per species in a treatment series were grown in the same hydroponic solution for the first 12 days, at which time the nitrogen concentration was reduced 100 times (0.01 mM) and again continuously harvested until day 28th. RGR decreased from 23.4% for Coreopsis lanceoloata to 93.8% for Echinacea purpurea following the nutrient stress. However, plasticity in the underlying components allowed RGR to subsequently recover to varying amounts in the different species, completely returning to the RGR in the control series in C. lanceolata by the end of the experiment. We relate these changes in RGR to its underlying components and discuss these results in the context of plant strategy theory.
Key words: biomass allocation plasticity, relative growth rate, nitrogen availability, temporal variation