By: Shen Yichen
Hu Qinxi
Soon Hao Jing
Terence Tim
Our Project
How does pH affect seed germination?
In this project, you will select chemicals that
are acidic in nature (e.g. household chemicals)
and determine their effect on germinating
green gram seedlings. The effect of acidic
solutions at different dilutions should be tried
as well. Devise parameters to measure the
effect of the chemicals, such as the number of
days to germinate. Extrapolate your finding to
the effect of acid rain on vegetation.
From Notes
Hypothesis
As the acidic level of the base
increases, the germination
rate of seeds will decrease.
Materials and Equipment
1. Red beans (1 pack)
2. Cotton wool (half a pack)
3. Dropper (x2)
4. pH Indicators (x20)
5. Petri Dishes (x5)
6. 500ml beakers (x2)
7. 100ml Measuring Cylinder
8. Hydrochloric Acid (1M HCl) (500ml)
9. Acetic Acid (1M CH3 COOH) (300ml)
10. Citric Acid (20%) (300ml)
What We Did
Trial 1
We did some research on red beans(Azuki bean) and acids. Next we
spread cotton wool in the Petri dish and used them as the base for
growing the seeds. We had to use red beans instead of green ones
because green beans germinate too quickly for us to observe the
differences in the time of germination. We then diluted hydrochloric
acid with water and watered the seeds in each Petri dish with the
same amount of acids of different dilutions. We then checked for
the number of days the seeds took to germinate.
Trial 2
We researched on the pH level of normal fertilizers, and tested the
pH level of the tap water we used to water the plant. This time we
used two different acids to see whether the types of acid will affect
germination. Then we did the same thing to each Petri dish just like
in Trial 1.
Results for Trial 1
Petri
Dish A
pH
level
2
Time of
germination
6.37pm
30 Mar
Petri
3
7.03pm
Dish B
30 Mar
Petri
4
6.45am
Dish C
30 Mar
Contro 6 to 7 6.40pm
l (D)
29 Mar
Control
pH 2
Other Observation and Research
Observations
Research
•Green mould like
stuff start appearing
on the cotton wool
after a few days in
the pH 2 and 3 dishes.
The ideal pH level
for soil is pH 6-7
because at this level,
most of the
nutrients and
minerals are present
in the soil.
•The cotton wool in
the control turned
brownish
•The cotton wool in
the pH 4 have some
black spots on it
The pH level for
normal fertilisers
however, is 5-6.
pH Level
Petri
dish A
pH4
(citric)
Petri
pH3
dish B (citric)
Petri
pH4
dish C (acetic)
Petri
pH3
dish D (acetic)
Control pH6-7
(E)
(Water)
Time of
germination
6pm
6 Apr
8pm
7 Apr
7am
6 Apr
6am
9 Apr
7am
9 Apr
Citric pH 3
Acetic pH 3
A little acid in the soil doesn’t really
affect the rate of germination.
However too much acid cause slow
germination and even abnormal
occurring (green stuff appearing). Also
different acids have different effects
on plants.
So, our hypothesis is partially correct.
Causes
•Volcanoes
•Natural biological process
•Power plants
•Motorcars
•Factories
Effect on forests
include slow growth
and causing damage
to plants which in
turn leave them
more vulnerable to
threats. They also
cause mineral and
nutrient loss from
the soil.