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Germination Physiology
Before preparing any seeds, make sure you have all materials needed, and have read and understood all the instructions below! Each individual will need to prepare a total of 12 dishes using the procedure described below. Each dish, not each seed, will yield one data point. In total, your team will therefore produce 12 data points per condition (48 data points total).
Line each petri dish with 1 filter paper disc and saturate the paper with water. Use a plastic transfer pipet to determine how much water is required and then use the same amount for each dish. Err on the side of excess water.
Scatter approximately 20 seeds onto the paper in each dish (you can do exact counts later). Seeds should not be piled on top of one another! Prepare half of the dishes with lettuce seeds, and the other half with lentils.
Immediately replace the lid and seal the edges with a strip of Parafilm. The Parafilm is critical to prevent the seeds from drying out, as drying out could distort the results.
Wrap 3 dishes of lettuce seeds and 3 dishes of lentils in aluminum foil so that no light can penetrate the foil at all—that’s a total of 6 dishes in the dark*. You can put all of the dishes into a single aluminum foil “packet.” Do this no more than 5 MINUTES after moistening the seeds. Molecular events can be set in motion very quickly on exposure to moisture!
The remaining 6 dishes will serve as “light” treatment groups.
Now place all of your seeds in a well-lit location such as a windowsill, where the temperature is reasonably stable (e.g. there aren’t any big air drafts or other things that might disturb them).
For each seed type, monitor the light-exposed seeds for emergence of the radicles at regular time intervals: 6 hours, 12 hours, 18 hours, and 24 hours is ideal; if you are still waiting past the 24-hour mark, switch to checking the seeds every 12 hours. Do not open the aluminum foil for the seeds in the dark to check on them. After the radicles have emerged from almost all the seeds in any one of the dishes in the light (this should occur after about 24 hours), you can terminate the experiment and then open the foil to count the following in all of the dishes (light and dark) for that treatment:
The number of seeds that have germinated
The number of seeds that have not germinated
Note: This is the first time that dishes inside the foil are removed and exposed to light. Germination is defined as splitting of the seed coat and emergence of the radicle (embryonic root). This may not be easy to see with the naked eye. I encourage you to use a magnifying hand lens!
Also include a final qualitative assessment of dish dampness (still damp, barely damp, dry) since, as noted above, excessive drying (e.g. if the Parafilm was not tight) could affect the results.
After collecting your data, leave the 6 dishes that were in the dark (* above) exposed to light for an additional 24 hours. After this, recount the number of seeds that have germinated or not. If the seeds in the dark have not germinated, this step serves as an important positive control for seed viability.
Team Check-In Meeting Midway Through the Pilot Experiment
Team Check-In Meeting Midway Through the Pilot Experiment
At the end of the first week, arrange a time to meet face-to-face as team. Your choice whether that’s in person, Zoom, Google Meet, conference call, or something else -- but IT CANNOT BE A TEXT CHAIN OR GROUP CHAT! You must actually be able to speak to each other!
At your check-in meeting, you should accomplish the following things. You'll be uploading your notes and answering a few questions in the Pilot Check-in: Team Assignment in Canvas
Sharing Observations
Sharing Observations
Choose one person to take notes in their lab notebook.
Each team member should describe what they have observed from their experiments so far.
Did anything surprising happen?
Were there any challenges that came up? If so, were they able to resolve the problems? If not, what steps need to be taken next? Should this be brought up in your meeting with me?
Would it be useful to repeat or redo any aspects of the experiment? If any aspects are redone, what changes will be made?
Team Sharing & Assignment
Team Sharing & Assignment
Upload your discussion notes to Canvas (if notes were handwritten, upload a photo)
Answer the Team Assignment questions in Canvas
Schedule your team meeting with me
Every student should write any decisions made at the meeting down in their own lab book. Take a photo of your personal notes and upload it to Canvas.
Individual Sharing & Assignment at the End of the Pilot Experiment
Individual Sharing & Assignment at the End of the Pilot Experiment
use your phone to scan your notes, and upload the resulting pdf to your team's shared drive
enter your data into your team’s shared Google Sheet
answer questions on Canvas (Pilot Wrap-up: Individual Assignment)
Team Meeting at the End of the Pilot Experiment
Team Meeting at the End of the Pilot Experiment
Arrange a time to meet face-to-face as team (your choice whether that’s in person, Zoom, Google Meet, conference call, or something else -- but IT CANNOT BE A TEXT CHAIN OR GROUP CHAT! You must actually be able to speak to each other!)
At your meeting, you should accomplish the following things. You'll be uploading your notes and answering a few questions in the Pilot Wrap-up: Team Assignment in Canvas
Choose one person to take notes.
Verify that all students have added their data to the shared data sheet
Does anyone have questions about the data?
Did anyone encounter unexpected problems or challenges while collecting data?
Is there anything from this experience that will be especially valuable in planning your main experiments?
Team Sharing & Assignment
Team Sharing & Assignment
Upload your discussion notes to Canvas (if notes were handwritten, upload a photo)
Answer the Team Assignment questions in Canvas
Tips for Data Analysis and Creating Your Pilot Figure
Tips for Data Analysis and Creating Your Pilot Figure
Calculate the percent germination for each dish (dividing the number of seeds that have germinated by the total number of seeds in that dish). Each percent germination calculation (not each seed) thus yields one “raw” data point. A reminder that the 6 dishes with dark seeds have two sets of counts, once at the termination of the experiment and then again 24 hours later as a control to verify seed viability.
Pilot experiment figure: Construct a simple graph comparing the mean germination rate across each of the four different treatments. Also include results from your positive control.
In your lab notebook, briefly state some initial conclusions based on the results obtained. Do your data support the hypothesis that seed germination is light-sensitive?
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