Science Buddies: "Ask an Expert"

Hi,
I was wondering if I could get some help on my science project. I'm trying to study whether or not seed size affects how quickly a seed germinates. I was thinking I could plant different sized seeds of the same type and see which germinates faster. I just need to know what kind of seeds to use, and how to measure which germinates first. I know some seeds, like beans, can be germinated outside of soil. I also thought that maybe I could see which seed emerged from the soil as root or stem first, or which visibly grew the most in a set amount of time. Any suggestions? Thanks!

Hi specialr,

This sounds like a great project. I think using a seed that will germinate without soil will make you observations easier. For example radish seeds will germinate on a wet surface. Take a look at these scibuddies projects. They are looking at different treatments than yours. But you should be able to get an idea for how they handled the seeds and how they measured germination.

https://www.sciencebuddies.org/science- ... p039.shtml
https://www.sciencebuddies.org/science- ... p008.shtml
https://www.sciencebuddies.org/science- ... p036.shtml
https://www.sciencebuddies.org/science- ... p005.shtml

Let me know if you have anymore questions

Kierstyn

Hi Specialr - In addition to the Project Idea links Kierstyn offered, and the advice about potentially working without soil, you may find some information about measuring and monitoring growth in this Project Guide resource:

https://www.sciencebuddies.org/science- ... l?from=AAE


Amy
Science Buddies

OK, thanks! I'd actually already decided to use radish seeds. I am going to germinate them outside of soil, with dampened paper towels. I have a seed starter, which you can put petri dishes in and cover them to create total darkness. I was thinking I could put damp paper towels inside the petri dishes and germinate the radish seeds in them. My teacher suggested I measure the length of my seeds under a microscope with a micro ruler (I think that's what it was called-- is that correct?). Since dormancy ends and germination begins when the seed opens or cracks, my dependent variable was going to be how long it took the big vs. small seeds to germinate. My only questions are:
-I was having trouble finding information on whether or not radish seeds need light or darkness to germinate. And if they need light, how would I make sure all the seeds have a consistent amount of light?
-How would I go about setting up my petri dishes with damp paper towels?
-How many seeds would you suggest I use?

Thank you so much! And if I could get an answer ASAP, that would be great, just because my experimental design is due tomorrow!

Hi specialr,

Radish seeds are a really good choice because they germinate and grow quickly and easily.

1. All of the procedures I posted before place the radish seeds in indirect sunlight. You can leave the petri dishes on a table or counter near a window where they won't be disturbed. If you place all the petri dishes in the same spot they should get the same amount of light. Don't stack them or the bottom ones won't get any light.

2. I would put paper towels in the bottom of each of the petri dishes. Then use an eye dropper to slowly add water to the paper towel until it is damp. Don't add to much water you don't want the paper towel to be dripping. Then you can place your seeds and cover the plates. You can find eye droppers at the drug store.

3. I would use at least 6 or 10 seeds. You don't want to use so many that they are touching in your dishes. You also want to leave enough room for the seedlings to spread out as they germinate and grow. Take a look at the second and third links I posted above. There is a picture of how the seeds are placed.

Let me know if you have any questions,
Kierstyn

OK, that's great. Thanks! And one last question-- would you recommend I put a lid on the petri dishes? I was thinking I wouldn't cover the dish, because oxygen is a necessary resource during germination, and I wouldn't want lack of oxygen interfering with my results.

You want to cover your petri dish in some way so that the paper towel stays moist. I think there will be enough oxygen if you cover the plates. Plant biologists germinate seeds in petri plates that are covered. If you are worried about it try sealing the plates in large Ziploc baggies; similar to what they did in the other radish experiments.

Kierstyn

Thank you!