A Little Bit More
Many people want to collect seeds in the fall and then grow various trees, shrubs, or flowers without realizing the importance of the over-wintering, dormant period necessary for germination. Although there are multiple ways that plants have adapted to ensure the germination of their seeds, one of the most common is the chemical changes that take place during winter dormancy. Although temperatures vary for different species, the approximate “optimal” temperature for trees is about 4°C (34°F) for a period of at least 8-10 weeks, maybe longer.
If you’ve collected seeds that need a dormant period, you’ll need to take some action to provide the proper temperature for the proper time interval if you expect germination. Horticulturalists use a process called stratification, that includes chilling and moisture to prepare seeds for germination. Stratification is simply an artificial process that simulates the natural conditions seeds experience during winter. Many people find that placing seeds in a plastic bag in the refrigerator with moist (not wet) sand or vermiculite for 8-10 weeks provides adequate stratification. You can place these plastic bags outside in an unheated garage too, for example, but you’ll have to watch out for hungry animals.
Although this unit’s illustration has focused on an acorn, it should be pointed out that this particular acorn is from the Red Oak group. The Red Oak group (these usually have sharp, pointed tips on their leaves) require 2 growing seasons for their seeds (acorns) to mature and these do require a dormant period before germination. The White Oak group (these usually have rounded tips on their leaves) on the other hand, require only 1 growing season for their seeds to mature and these actually begin germination by sending out their root at the end of that first growing season. Cold weather soon stops this process and the white oak group acorns then complete germination by sending up their leaves in the spring.
Activities
Pop Ups
Objectives: Students see what may be dormant in bare soil
Materials: Scoop of soil, plastic bag (terrarium optional)
Here’s a very straight-forward activity that may be as fun/educational for you as for the students. The “Winter Wait” unit has discussed dormant seeds so now let’s have a look at what is dormant in a bit of your own local soil.
To get started, you’re going to need to think a bit about the best place for collecting your sample soil. I realize that some will not have any local areas where much soil can be scooped but almost everyone should have access to at least a wee bit. Of course, the idea here is to obtain soil that has dormant seeds, whether they’re weed seeds or not is not important.
1. Think about your local area and decide on an area where you can collect a small shovel or trowel of soil for study. You want soil that has been exposed to the elements and also is likely to have a variety of seeds that have accumulated over the winter.
2. Once you’ve selected your site, you’ll want to scoop up a quantity you can take back to your classroom for observation. Don’t take a vertical, deep “bite” but take a shallow, scoop from the soil surface that will maximize the surface area of soil that your shovel/trowel will hold. Soil of 1-2” in depth is plenty for this exercise.
3. Keep your soil scoop as intact as you can and bring back to your classroom. (Your soil may not hold together, but don’t let that worry you – keep the soil as intact as you can but if not, your dormant seeds will still be able to sprout)
4. If you have a terrarium, that’s great, but if not, a clear plastic bag will work. Place the scoop, right-side-up, in the terrarium/bag, moisten lightly, and place in a warm, light area of your room. (Don’t place in direct sunlight or near a heater)
5. Be sure to cover the terrarium or close the plastic bag so your miniature greenhouse stays moist (there will be some condensation on the glass/plastic, which is fine – if you think it’s getting too wet, simply open and allow some moisture to escape).
6. Depending on the kinds of seeds present and the temperature of the room, you should begin to see some sprouting activity within 10 days to 2 weeks (some of the dormant seeds may have already begun germination when you collected your soil!).
7. Depending on your setup and space, you may want to continue to keep the scoop moist and growing over an extended period. Keep in mind that different kinds of seeds have different germination rates so you may see something sprouting this week, go a week without anything, and then see something completely new sprout.
8. Keep in mind that you’ll probably be seeing some creepy-crawlies in your soil too. Your containers should keep them within so this shouldn’t be a problem. If you’re able to identify some of the sprouting plants, once they’ve achieved some size, you’ll have added another dimension to the exercise for your students. (ID Hint – many of the plants growing in your scoop of soil will be the same species as those plants surrounding the scoop selection site!)
Key Concepts
Behavior and Regulation, Growth and Development
Questions
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Posted by Leslie on April 06, 2005 at 11:19 AM
Q: I want to help indagerd animals wheni grow up..but i i want to work mostly with the catlike animals...like clouded leapords,lions,cheatas,mountain lions and other type is there a spacific type of job like that out there?
A: Absolutely, there are jobs that have people working closely with all kinds of animals. Although zoos are not the only places you might be able to work with the cats, they are probably the most likely place for employment. Today's zoos work hard to help all kinds of endangered species and would be a very exciting and rewarding place to work. You've heard it before but it's true - get a good education and there will be many, many more opportunities for you to choose from. Good luck to you.