What
makes it possible to put all germination science projects on
single page is their similarity. Plants are complex organisms. They can
be very different as an adult form and have very different lifecycles,
sizes and habitats yet they all start life as a seed. So all you need
for this kind of project is some seeds, water, soil and a bit of
patience.
Project Overview.
First of all it's good
to do a bit of research on plant seeds.
You probably know that
all seeds of flowering plants are divided into 2 major groups:
Monocotyledons
or monocots and Dicotyledons
or Dicots. If you open up the seed you'll see the difference
– embryo of monocots
have only single leaf while embryo of dicots have 2 embryo leafs. There
are many other important differences which we will not discuss
here.
Seeds of different
species store different amounts of nutrients to feed
an embryo. Large seeds with lots of food storage usually found among
dicots. Depending on our experiment we may choose to use seeds with
plenty of food storage. For example if you'd decided to do simple
observational project on the root system development you could choose
some bean or avocado seed. You could setup them over the glass of water
to observe roots growing. That would allow you to take photos or even
make a time-lapse movie of the root growth!
Time required for seed
germination is another important variable we
want to keep in mind. Some species produce shoots faster then another.
Time may vary from one-two days to few weeks! So if you time limited or
your experiment requires multiple repetitions you may want to choose
fastest seeds of them all.
Good model plants for
germination science projects are:
Soy beans (dicot) germination time 3-4
days.
Sunflower seeds (dicot)germination time
10-14 days.
Butter beans (dicot)germination time
6-18 days.
Corn seeds (monocot)germination time
4-12 days.
At the very first stage
of its life seeds are self contained. All they
need is a bit of light and water. Within they have all important
nutrients to develop. By the way this is the important difference
between higher plants and seedless plants like ferns or algae.
However, there much more
parameters some of them are subtle that may affect plant germination
and even its survival.
Here is the little list
of the parameters that you can test in germination science projects:
Will light
affect germination time?
What about temperature?
Wetness?
Amount of oxigen
in the
atmosphere?
Amount of carbon
dioxide in
the atmosphere?
Bacterial
or mold contamination of the soil?
How deep
seed can be planted and still survive?
How competition
affect germination?
Is competition between different species
affect germination?
Is competition from grown plants affect
germination?
Does magnetic
field affect germination rate?
How pH
affect germination?
Does rooting
hormone speed up germination?
How roothing
hormone affect
root
system development?
Try to add some more
questions to this list!
So what exectly
happens when you plant seeds in the wet soil?
Plant embryo lives in
anabiosis state. In this state all life processes
are almost stopped. Cells of embryo do not grow or divide. There is
almost no breathing. Embryo spend almost no energy. Time stopped for
it. Seed is like a starship with hybernated astronaut flying to some
distant star.
Most of the seeds have
an internal anti-alarm-clock program that force
them spend certain time (few weeks or even months) sleeping until
germination process can be turned on. This program is very important –
it helps plants to survive hostile seasons.
When time comes usually
water and temperature starts germination process. Seed starship arrived
to its destination.
Seed coat (outer layer
of the seed) becomes transparent for the water.
Water fills the embryo cells bringing it back to life, turning on
chains of enzyme reactions in the cells and dissolving nutrients in the
endosperm, making them available for the embryo.
Seed grows in volume.
The root comes out and anchor it in the soil.
Then embryo leaf(s) appear and for some time embryo grows feeding
mostly on the endosperm. Then root system develops and first real
leaves
appear.
Materials.
For most of germination
science projects you may need:
Seeds. You should select them carefully
making sure that
all of them look good. There should not be obvious damage to the seed
coat, signs of mold or inconsistency in coat color. For any germination
experiment you'll need at least 2 groups of seeds.
One of them will be our test group(s) and another one – control group.
Plates, jars or petri dishes to soak and
sprout the seeds.
You may also need a piece of cloth. It's convenient to soak your seeds
in
water in petri dishes. Some experiments may be completely done in the
dishes. The lid is transparent so you can observe results through them.
Also it looks very scientific. :)
Germination tray and potting mix. You can
buy one or you can make one.
Water.
This is basic materials
that you will need for most of the experiments.
For some experiments you'll need more tools/materials. Check experiment
links for specific information.
Select and separate seeds in few groups -
control group and experimental groups (as many as you need).
Set up environment conditions for test
group and control group(s) in
such a way that all conditions are exactly the same except the one
that you're testing.
Observe and measure changes that happens
to the seed and record the results.
When experiment is done?
Well, that's up to you
to decide and may depend on the experiment
goals. In most cases we would suggest experiment complete when 50% of
the sprouts in the control group will achieve certain length of root or
leafs. Note this condition is only our suggestion, and may depend on
the type of the experiment. For example it probably would not be valid
if you compare germination of two different species.