Science Buddies: "Ask an Expert"

I have a science project proposal and the question is whether or not cutting the invasive water weed Egeria densa affects how the water weed grows. My experiment will include 20 specimens of Egeria densa, 10 of which are cut, and the other 10 are left alone. I will record the growth every week and the experimentation will end 2 months later. What is the best way to measure the growth of Egeria densa: length, mass, surface area, or dry weight?

Hi Specialk16,

This sounds like this will be an excellent project and your project will be answering a question about an important environmental problem.

There are several ways to measure plant growth. Here is a sciencebuddies project guide that describes how to measure plant growth by weighing the plants periodically during the experiment and then drying and weighing the samples at the end of the experiment:

https://www.sciencebuddies.org/science- ... owth.shtml

The next website describes other approaches to measuring Egeria, including measuring photosynthetic response, carbon, hydrogen and nitrogen analysis, as well as measuring the tip, bud, roots, and lower stems of individual plants with a ruler. The details are included in the slide show that is part of this website, and there is an e-mail address for researcher who has recently conducted research on this topic.

http://www.clr.pdx.edu/projects/plants/egeria.php

You probably do not have access to an elemental analyzer, but you could certainly weigh and measure the length of various parts of the plant.

I hope this helps. Do let us know if you have any other questions.


Donna Hardy

Thank you, this helps a lot.