Abstract Detail

Ecological Section

Hembrough, Ashley [1], Borowicz, Victoria [1].

Factors Constraining the Reproductive Output of Baptisia alba macrophylla.

Baptisia alba macrophylla, a native, herbaceous perennial legume, produces inflorescences with a large number of flowers, yet matures a limited number of fruits. We hypothesized that (i) the number of pods initiated, (ii) the number of pods matured, and (iii) the number of seeds matured by B. alba macrophylla is optimized based on resource availability at each stage of development, but this optimal number is further compromised by extrinsic factors such as pollen limitation and pre-dispersal seed predation by the weevil Apion rostrum. We tested this hypothesis by randomly assigning whole plants to one of two fertilizer treatments (no fertilizer, application of granular fertilizer prior to first flowering and post flowering) and one of two seed predation treatments (no pesticide, application of Tanglefoot® Insect Barrier). Individual flowers were then assigned to one of two pollination treatments (natural pollination, natural pollination supplemented with hand-pollinated outcrossing).
The 33 plants produced a grand total of 4,821 flowers but less than 15% of these flowers ultimately matured fruits. Flowers that were supplemented with hand pollination initiated significantly more fruits per flower (mean+ se: 0.9157 + 0.01232) than flowers that were not supplemented with hand pollination (0.8879 + 0.01516), but this effect was only observed on plants that were not treated with Tanglefoot®. Application of Tanglefoot® significantly increased the proportion of initiated fruits that matured, suggesting that plants abort heavily-attacked fruits. Pre-dispersal seed predation by A. rostrum significantly reduced the mean number of seeds matured/pod by B. alba macrophylla, but neither resource availability nor pollen availability were significant factors. Further, we conclude that the number of seeds matured by B. alba macrophylla is severely impacted by pre-dispersal seed predation by weevil larvae, but neither resource availability nor pollen availability have significant effects on the total number of seeds matured by this native legume.

1 - Illinois State University, School of Biological Sciences, Campus Box 4120, Normal, IL, 61790-4120, USA

Keywords:
seed predation
legume
tallgrass prairie
pollination
nutrients.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Hall D/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 5:30 PM
Number: PEC030
Abstract ID:636
Candidate for Awards:Ecological Section Best Graduate Student Poster