ScienceCast: Tomas Carlo's Research on Seed Movement and Germination

Uploaded by PennStateScience on 13.10.2010

Plant species extend their geographic range by seed dispersal. That is, wind and birds
carry seeds across distances, allowing a plant species to grow in an area far away from its
original territory.
A Penn State biologist, Tomas Carlo, and his collaborators have developed a new method
for tracking seed movement and germination. The technique will be useful for studying
how plants adjust to global climate change by finding new locations in which to grow.
Carlo and his team tested the new approach in the field with several species of plants
and trees, but they conducted their most thorough tests by spraying wild chili-pepper plants
in southern Arizona with a nitrogen-15 solution in the form of urea. Later, after the plant's
seeds had been dispersed across a distance by birds, Carlo's team collected the seeds
and seedlings, ground them up, and placed a tiny sub-sample into a laboratory device,
called a mass spectrometer, to measure the amount of nitrogen-15. The method was like
finding a needle -- or seed -- in a haystack. The team found that the seeds and seedlings
that came from the plant that they had treated had strong nitrogen-15 signatures.
In addition, the team was able to estimate the number of seeds in their samples that
had come from treated plants versus untreated plants.
For Sciencecast, I'm Katrina Voss.