PARENT SESSION
Poster Session # 15: Plant Ecology.

Wednesday, August 6 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.

Physiological and morphological plasticity of plants nutrient foraging.

Wang, Lixin¹, Mou, Paul¹, Robert, Jones², ¹ University of North Carolina at Greensboro, Greensboro, North Carolina, U.S.² Virginia Polytechnic Institute and State University, Blacksburg, Virginia, U.S.

ABSTRACT- Plant root nutrient foraging ability in heterogeneous soil is enhanced by morphological, physiological, and demographical plasticity. We conducted a greenhouse experiment to examine root physiological and morphological plasticity of three plant species (Erechtites hieracifolia (L.) Raf, Pinus taeda L. and Liquidambar styraciflua L). Seeds were sown in 19-liter pots that were randomly assigned into two treatments: even fertilization or quarter fertilization. Each pot received 5 grams of slow-release fertilizer (N-P-K) after the seedlings were established (one plant per pot). In the even fertilization treatment (H), fertilizer was evenly applied to the surface of each pot, while in the quarter fertilization treatment (Q), all fertilizer was applied to one randomly selected quarter. As the plants reached adequate size (roots touching the pot edge), we injected 20 ml 5 atom % ¹⁵ N ammonium-nitrate solution (0.1 M or 0.29 M with red food dye) into a soil column of each pot. This procedure was performed to fertilized or unfertilized quarters in the Q treatment, or one randomly selected quarter in H treatment. This injection was repeated 24-hrs later at the same location. Plants were harvested 24-hrs after the second injection. The ¹⁵ N fertilized plug was collected first, then, aboveground plant parts and roots from each quarter were harvested. Fine roots from each plug were sorted, oven dried, weighed and prepared for ¹⁵ N analyses. The preliminary results demonstrated that root physiological plasticity for nutrient uptake differed significantly (p=0.05). Nutrient uptake rate by roots grown in enriched soil was the highest, followed by the roots grown in evenly fertilized pots. The root nutrient uptake rate in unfertilized quarters was the lowest. Root morphological plasticity of these species was significantly different (p<0.001), and the differences among species were significant. This finding agreed with our previous study results.

Key words: Heterogeneity, Root, Physiological plasticity